Table of contents

As Covid-19 spreads around the world, people have to make some change to avoid being infected. And due to the outbreak of COVID-19, the participants were not able to meet each other at the 5th International Conference on New Energy and Future Energy System (NEFES 2020) supposed to be held in Xi'an during July 14^th-17^th, 2020. Even though the conference was postponed to November 3^rd-6^th, some of the participants from other countries were still not able to visit China to attend NEFES2020 for COVID-19. So, the conference organizer located in Wuhan made a decision to hold it as an online conference (virtual conference without any physical participation and held by Microsoft Teams) during November 3^rd-6^th. Microsoft Teams Meeting provides a more effective way for us to hold an online conference via some function like sharing the presenters' Power Point or video, discussing in the chat box or taking pictures. However, there were also some shortcomings about online conference regarding time differences and internet conditions. Therefore, it is a way to hold an international conference online.

NEFES 2020 was sponsored by Harbin Institute of Technology, Weihai. It aims to provide a platform for researchers and practitioners in both industry and academia to share their latest achievements and discuss the possible challenges in terms of new energy and future energy system. This volume records the proceedings of NEFES 2020 and contains 85 rigorously selected manuscripts submitted to the online conference. All the manuscripts were selected depending on their quality and relevance to the conference.

One hundred and nine participants including presenters and listeners from a broad geographical coverage of counties including China, Australia, Switzerland, Italy, Spain, Romania, Indonesia, Iraq, Poland, Japan, Mexico, India, Russia, Germany and Iran joined NEFES2020 and made it a successful conference. The conference program included welcomes speech, 3 keynote speeches, 25 invited presentations, 11 oral presentations and 16 poster presentations. About 5 minutes were left for each oral presentation, the audience could raise up their hands before the session chair allowed them to ask questions or left message in the chat box as well as wrote an email to the presenters. The conference program was outlined as follows:

Welcome speech was delivered by Prof. Fuqiang Wang, School of New Energy, Harbin Institute of Technology (Weihai) of China for five minutes.

Three keynote speeches were from Prof. Mattheos Santamouris, University of New South Wales, Australia; Prof. Hui Jin, Xi'an Jiaotong University, China; Dr. Eric Johnson, Editor-in-chief emeritus of Environmental Impact Assessment Review and Managing Director of Atlantic Consulting, Switzerland. Each keynote speech lasted for 40 minutes and delivered on November 4^th.

The other online presentations were delivered by researchers, scholars and experts such as Prof. Riyi Lin, Prof. Zehui Chang, Dr. Liqiang Zhang, Dr. Yushi Liu, Prof. Chongchong Qi, Dr. Diana Enescu, Dr. Luigi Costanzo, Dr. Claudia Masselli, Dr. Jan Kazak. Each oral presentation lasted for 15-25 minutes. The topics of the online presentations covered New energy resources, New energy device, smart grid load and energy management, optical technologies for smart grid, Solar cell materials and lithium-ion batteries.

List of NEFES2020 Scientific Committee Members, General Chair, Chair of Technical Program Committee and Technical Program Committee are available in the pdf.

All papers published in this volume of IOP Conference Series: Earth and Environmental Science have been peer reviewed through processes administered by the Editors. Reviews were conducted by expert referees to the professional and scientific standards expected of a proceedings journal published by IOP Publishing.

• Type of peer review: Double-blind

• Describe criteria used by Reviewers when accepting/declining papers. Was there the opportunity to resubmit articles after revisions?

The reviewers used the conference review form to provide their comments and suggestions on the manuscripts. The Authors were asked to revise their original manuscripts in alignment with the reviewers' comments and suggestions for publication. An opportunity will be given to the authors to resubmit their manuscripts after revisions.

• Conference submission management system:

http://www.academicconf.com/Identity/Account/Login?confName=NEFES2020

• Number of submissions received:

216

• Number of submissions sent for review:

155

• Number of submissions accepted:

85

• Acceptance Rate (Number of Submissions Accepted / Number of Submissions Received X 100):

39%

• Average number of reviews per paper:

2

• Total number of reviewers involved:

190

• Any additional info on review process (ie plagiarism check system):

The conference uses iThenticate to check plagiarism and before sending the manuscripts to the publisher, plagiarism of manuscripts will be checked again.

• Contact person for queries:

Dr. Grigorios L. Kyriakopoulos

gregkyr@chemeng.ntua.gr

School of Electrical and Computer Engineering, National Technical University of Athens (NTUA), Greece.

Modern distribution network has a huge volume and a wide range of points, so the difficulty of construction and transformation of distribution network often lies not in technological innovation, but in the operability of planning scheme, adaptability and flexibility of network structure. Therefore, an optimization model of mesh planning for high reliability power supply in urban power grid is proposed. Firstly, the planning process is optimized to avoid the cyclic adjustment of power supply mesh and power supply unit division. Secondly, a target network architecture and power supply unit partition model for medium-voltage power grid are proposed, which can meet the double power demand of important power users and ensure no cross-supply between units. Finally, an example of mesh planning in a city center in Hubei Province of China is given, and the application of the optimization method is described in detail. The results show that the method is easy to carry out, and effectively improves the reliability of power supply in urban power grid.

The aim of this work is to employ computational fluid dynamics (CFD) modelling to elucidate the soot formation and entrainment processes when diesel as well as soy, palm and coconut methyl esters (biodiesel) are used in a light-duty diesel engine under varying operating conditions. ANSYS FLUENT 13, which is linked to a chemical kinetic model via CHEMKIN-CFD, a plug-in chemistry solver, is utilised. The soot entrainment focuses on thermophoretic soot deposition on the cylinder liner and soot transport into the crevice region via blowby. During the closed cycle combustion process, the mass of soot deposited on liner via thermophoresis is more significant than that transported into the crevice region through blowby, representing at least 95% of the total soot entrained. The percentage of entrained soot from the net amount of exhaust soot is dependent on the methyl ester type. Diesel results in the maximum soot entrainment with the largest averaged diameter while coconut methyl esters with short hydrocarbon chain length produces the smallest amount and size of entrained soot. Different saturation levels give rise to different soot entrainment processes under varying operating conditions. Overall, this work provides detailed insights into the main in-cylinder processes controlling soot entrainment for biodiesels.

Base on the ultra-low emission reconstruction project of the 2×600MW unit desulfurization system in the Northwest China. The desulfurization system synergistic dedusting technology route achieves ultra-low emission of soot under the premise of maximizing the use of existing equipment. Through the comparison of the three-stage roof demister, Tube type dedusting and demisting device and condensing type dedusting and demisting device technology, the three-stage roof demister is stable, mature and reliable, and widely used. Under the same transformation conditions, the cost of the three-level roof demister is lower than the other two dust removal and demisting devices.

A set of transportation process monitoring system for large power transformer transportation is developed, including transportation state intelligent acquisition terminal, monitoring system platform software and mobile app. The effectiveness of the system is verified in the actual transportation monitoring of converter transformer. It solves a series of problems existing in traditional methods, ensures the transportation safety of large electric power equipment and reduces the investment.

The secondary carry-over of the droplet and liquid film in the steam-water separator can influence the separation efficiency of the separator. The generation of the secondary droplets resulting from droplets impacting the water film of the wetted surface is one of the mechanisms of secondary carry-over. Therefore, the experimental investigation on water droplet impacting liquid film on inclined wetted surface is conducted through high-speed video camera. The subsequent form and evolution process once the droplet colliding with the inclined liquid film are obtained. The droplet splashing phenomenon and mechanism are explained. The qualitative analysis of influence of the initial droplet diameter, velocity and the inclination angle of the wet surface on the splashing behavior is conducted. The results reveal that with increasing angle of inclination of the wet surface, the critical velocity to generate the splashing phenomenon increases accordingly; the increasing initial droplet diameter leads to decreasing critical velocity; the splashing phenomenon is more likely to appear in cases with higher impacting velocity, larger initial droplet diameter and smaller inclination angle, under which conditions the number of secondary droplets generated increases and the splashing phenomenon is more obvious. The obtained experimental results are significant to the study of steam-water separation and can lay basis on design of the separator.

The problem of suppression of nonlinear random impulse disturbance in grid-connected wind power generation is studied in this paper. The mathematical model of grid side converter of wind power system is obtained by using Kirchhoff law. A feedback synchronization controller is designed to suppress the disturbance of current. With the help of Lyapunov stability theory, the effectiveness of the synchronization controller is verified. Further effectively restrain the nonlinear random disturbance caused by the current connected to the grid, so that the current generated by the wind turbine is synchronized with the current generated by the power grid. Finally, the simulation verification is carried out. The simulation results show that the effectiveness of the proposed control method.

In high temperature condition, lithium-ion batteries have a greater risk of thermal runaway. Lithium-ion batteries may be exposed to smoke, combustion, or even explosion, which poses a greater threat to humans and the environment. In this paper, the electro-thermal triggering method is used to induce thermal runaway of the lithium-ion batteries. The most representative ternary polymer lithium-ion battery (NMC), lithium cobalt oxide battery (LCO), lithium iron phosphate battery (LFP) in the market were selected as experimental samples, all using 18650 batteries, and then the state of charge of battery samples were adjusted to 0%, 30%, 50%, 100%. The thermal runaway reaction phenomenon of lithium-ion batteries and the surface temperature of the batteries were recorded. The positive electrode samples of the batteries were characterized by X-ray diffraction and electron microscopy, and the thermal runaway reaction products were analyzed. The results show that with the increase of the state of charge, the thermal runaway reactions of the batteries are more severe. Thermal runaway reaction products contain a large amount of toxic substances, and prevention and protection are necessary.

With development of smart grid, the stable operation of grid has put forward higher requirements for system dispatch. In particular, short-term load forecasting of power systems is a key factor of power grid management systems, which is related to the safety, economy, and stable operation of the smart grid. However, short-term electricity forecasting is affected by many external factors. It has complex characteristics, especially non-linear relationships, so it cannot be accurately predicted. Recently, Recurrent Neural Network based models have good performance in electricity forecasting because of their excellent ability to capture non-linear relationships. However, they cannot fully capture historical information, especially local historical information, which has an impact on prediction accuracy. In order to address these problems, we propose a scheme by combining STL decomposition and GRU model. Specifically, we first decompose the original time series into three different components by STL. The decomposition results are separately imported into the main prediction module, which uses two GRU networks with different structures to obtain the local and global dependencies of the data. We also add an autoregressive method to make the model more robust. The proposed scheme is validated based on real-world data, and the simulation results show that our proposed method can perfectly capture local and global information and achieve higher prediction accuracy than traditional models.

The forecasting of electricity consumption data plays an important role in the operation, planning, and security of the power grid. However, electricity data is affected by multiple factors and large fluctuations, which makes it difficult to accurately forecast. Traditionally, ARIMA and SVM are widely used for electricity forecasting based on historical consumption data. However, for non-stationary multi-feature data, traditional schemes cannot achieve deep feature mining of them, and the forecast results are inaccurate. To address this problem, this paper proposes an efficient short-term electricity forecasting approach based on EEMD-LSTM model. Firstly, we perform Savitzky-golay (SG) smoothing on the original data, and then introduce feature factors to the feature analysis. In particular, the proposed approach can reduce the random noise in data, as well as reduce the impact of data fluctuations, and effectively learn the long-term characteristics of the data. The simulation results show that, compared with ARIMA, LSTM, EMD-SVM, EMD-LSTM, the proposed approach can achieve better accuracy in the electricity forecasting.

To solve the problem that the PI-controlled three-level inverter can't achieve zero steady-state error on AC, a closed-loop control scheme using the PCI controller is proposed. The voltage and current double closed-loop control scheme is adopted. The circuit of diode-clamped three-level inverter is selected as the controlled object. And the PCI controller is designed. The zero steady-state error of three-level inverter based on the PCI control is analyzed in detail. Finally, the closed-loop control system of three-level inverter is simulated on the MATLAB/Simulink platform. The results show that the PCI control has good dynamic response ability and can accurately track various sudden loads. And then the correctness of theoretical analysis is verified.

The influence of catalyst Fe(NO₃)₃, CaO and composite catalysts on the thermostatic gasification process of char-CO₂ at atmospheric pressure were studied in this paper. The experimental conclusions Indicate that the catalytic effect of CaO is stronger than that of Fe(NO₃)₃ at relatively low gasification temperatures. As the gasification temperature increases, the catalytic gap between the two catalysts decreases. The catalytic effect of the composite catalyst at lower gasification temperatures is between the single component catalysts CaO and Fe(NO₃)₃. When the gasification temperature exceeds 850°C, the promoting effect of the composite catalyst is better than that of the to single-component catalysts. After adding composite catalyst, the time of the coal char is shorter by 103 minutes than the original char, which is shortened by 18 minutes compared with the two single-component catalysts, and the gasification temperature is lowered by 100°C, lower than 120°C of one-component CaO, and higher than 90°C of Fe(NO₃)₃.

Implementation of renewable energy resources (RES) with the use of knowledge-based approach requires systems which enable to combine data from different databases in order to multidimensional character of analysed factors. Therefore, this study provides the decision support system for the planning of hybrid renewable energy technologies designed for regional authorities. The system in this research integrates two RES: solar and wind. Moreover, it combines energy potential data with administrative division and data on land cover. Presented functionality shows the ability of single-element filtering as well as multi-element filtering which gives the opportunity visual data discovery. The novel decision support system designed in this research can constitute an effective instrument, which can help regional decision-makers to locate single-source as well as hybrid RES installations to meet the requirements of renewable energy production. The systems were designed for the case of Lubuskie Voivodeship (Poland). However, besides the fact of customized system for one region, the use of universal databases allows to prepare similar tool for any other region in European Union.

The paper studies the difference between two-terminal Line Commutate Converter Based High Voltage Direct Current (LCC-HVDC) and three-terminal LCC-HVDC control and protection system relying on the Yun-gui Interconnection Project of China Southern Grid (CSG). Contraposing the difference of topology between two-terminal LCC-HVDC and three-terminal LCC-HVDC, the paper introduces several special topology structures of three-terminal LCC-HVDC. Then the paper conducts comparative analysis on control strategy, protection strategy and communication strategy between the two-terminal LCC-HVDC and the three-terminal LCC-HVDC. Finally, the paper illustrates the unique key problems of three-terminal LCC-HVDC and solving ideas, which has guiding significance on three-terminal LCC-HVDC engineering application.

The distribution network is the end link of the power grid. The level of management directly affects the power supply capacity and power quality. It is related to the operation level and social image of the power grid enterprise. The transformer is a very important component in the distribution network. The transformer is continuously safe and stable. Grid power supply reliability. In this context, this paper proposes an intelligent gateway intelligent fault detection algorithm for transformer operation failure, which collects data of transformers in multiple dimensions and multiple source channels, such as electrical variables and non-electrical variables. Correlation analysis and causality analysis of the data to achieve an all-round warning of transformer operation failure. The traditional method of transformer fault warning is solved by relying on the special gas concentration or transformer vibration signal generated by the fault of the transformer fault to solve the problem of fault identification and early warning singleness and low reliability, and fully exert the technical advantages of the Internet of Things and data mining. The evaluation value of the five "ancestor" elements is 0.2, 0.25, 0.15, 0.3, 0.1. Transformer operation fault trend early warning coefficient is set to 0.80. Once the early warning coefficient is found to exceed 0.80 during data collection and mining analysis, a transformer failure early warning will be issued, which can facilitate grid operators' intervention and control in advance. The actual calculation case also demonstrates the correctness and effectiveness of the intelligent mining algorithm. This paper provides an effective support for the development and application of big data technology in the distribution network.

In view of the low output power and high power density of ultrasonic power supply, a high power ultrasonic power supply based on 9-level inverter technology is proposed. The inverter of the power supply consists of two H-bridge units cascaded to form a 9-level converter, which outputs the 9-level voltage waveform, which can significantly improve the output power of the ultrasonic power supply, reduce the inductance of the matching network, and reduce the power density of the ultrasonic wave. The phase difference method based on PI control is used to track the resonance frequency. By analyzing the system structure, working principle and control strategy of the ultrasonic power supply, modeling and simulation were conducted on Matlab/Simulink to verify the feasibility and effectiveness of the scheme.

In order to overcome the disadvantages of installing mechanical sensors and the problems of chattering and low observation accuracy in traditional sliding mode observer sensorless control, a two-stage filter Sliding Mode Observer (SMO) is proposed in this paper. By collecting the current and voltage of the Permanent Magnet Synchronous Motor (PMSM), the SMO algorithm is realized by using the state equation of the motor in the synchronous stationary coordinate system; the position of the rotor is estimated by the arc tangent function, the observation accuracy of the rotor position is improved by increasing phase compensation; the variable cut-off frequency filter is introduced to make the Low Pass Filter (LPF) cut-off frequency can be self-adjusted with the change of rotational speed, which improves the estimation accuracy of rotor position at different rotational speeds. Kalman filter is introduced to form a two-stage filter with variable cut-off frequency LPF, which greatly weakens the chattering of the motor and reduces the observation error. Finally, the simulation is carried out under MATLAB/Simulink. The simulation results show that the PMSM vector control system with two-stage filter sliding mode observer has high estimation accuracy, good dynamic and steady-state performance, strong anti-jamming ability and robustness.

The floating nuclear power plant (FNPP) is a solution to the thermal supply in offshore oil and gas fields, including the applications in thermal recovery and flow assurance. The output power of marine reactors under development in China matches the thermal demand of offshore oil fields. In order to analyse the thermal supply mode, the following aspects are investigated: the application scenarios, the thermal loss of the thermal supply pipeline, and the selection of platform type. Then, a case study is presented to illustrate the applicability of FNPP in the Bohai Sea for the enhancement of oil recovery. The case shows that the current solution works well with the offshore marginal oil field. The future solution is also discussed as to further improve the economy of FNPP.

According to the system requirement of a certain type of aviation piston engine, the reconstruction and matching of fuel injection system is carried out. The schematic design of the air-assisted injection assembly and the improvement of pressure regulator assembly are completed. After that, the air-assisted direct injection system is studied experimentally. The results reveal the effect of injection parameters and injection pressures on the system flow characteristics and spray characteristics. The effects of gasoline and kerosene on the actual engine performance are compared. The test results show that the self-designed air-assisted direct injection system can meet the system fuel injection requirements. In addition, the effect of injection pressure on the spray width is more noticeable than other spray characteristics.

In order to improve the load regulation capability of the power grid, verification of the minimum boundary output characteristics of deep peak regulation of coal-fired units was carried out. Considering the safety, stability, environmental protection, and energy saving indicators, the minimum output stability evaluation method was discussed in a 300MW coal-fired unit, and the ultra-low combustion stability target of 25% of rated load was completed. This has important guiding significance for approving the output characteristics of units, carrying out precise load regulation, and expanding new energy consumption.

SA-LA binary composite phase change material was prepared by mixing stearic acid (SA) and lauric acid (LA) in different mass fractions, and tested for thermal properties. The results indicate that composite PCM has a lowest peak melting point of 42.9°C, thus suitable for application in solar cell thermal control system. In addition, PV/PCM solar cell thermal control prototypes with different PCM thicknesses were designed and tested for thermal and electrical properties. The effects of different PCM volume on solar cell thermal control properties were studied, showing that compared with non-PCM systems, solar cell temperature in the PV/PCM system was reduced by more than 20°C, with output power increased by more than 11%. The research results provide experimental references for the preparation of SA-LA composite phase change materials and their application in thermal control of solar cells.

Three composite phase change materials (PCM) with peak melting points of 42°C, 50°C and 58°C were prepared using different mass fractions of stearic acid (SA) and lauric acid (LA). A thermal control model structure of thermoelectric generation/PCM (TG/PCM) was designed using PCM, and analyzed for its internal thermal conversion, transmission and storage mechanisms. In addition, TG/PCM experimental prototypes with PCM melting points at 42°C, 50°C and 58°C were designed and tested for their temperature control properties and output power. The results showed that under PCM melting points of 42°C, 50°C and 58°C, temperature difference between the cold and hot end of the TG/PCM prototype thermoelectric battery was maintained above 8°C for 70 minutes, 45 minutes and 27 minutes, respectively. The total energy of system output power above 6mW was 73.9J, 52.4J and 18.9J.

Quite large amount of heat generated in various industrial processes was wasted. Recovering the waste heat can save cost and benefit the environment protection. The device that convert heat energy to electricity is called thermoelectric generator (TEG), and therefore it can be used for waste heat recovery. Improving the efficiency is the main direction of present study. The configuration and geometry of the thermoelectric legs are proved can influence the thermoelectric performance of the thermoelectric generator. Compared with the conventional TEG which is assembled with symmetrical (rectangular) legs, asymmetrical thermoelectric generator (ATEG) has a greater temperature gradient in a leg due to the convergent geometry which can reduce overall thermal conduction of the device and Thomson effect is also harnessed. In this study, three-dimensional finite element analysis (COMSOL) is employed to investigate the numerical simulations of a segmented pyramidal thermoelectric generator (SPTEG) and a segmented cone thermoelectric generator (SCTEG) to optimize the leg length ratio of two materials, and it's effect on the electrical and mechanical performances of SPTEG and SCTEG was also studied. Results obtained shows that the height ratio of SATEG can influence electrical and mechanical performances and the optimum height ratio provided a better electrical performance while thermal stress developed in leg was less. In addition, the open-circuit voltage of two types SATEG is similar because they have the same cross sectional area and the same volume, however, SCTEG has a dispersive thermal stress distribution while the thermal stress of SPTEG concentrates in four corners. Compared to the maximum von Mises stress in SPTEG, the maximum von Mises stress in SCTEG reduced about 10%. Results obtained from this study would provide references in producing and design of segmented asymmetrical thermoelectric generators.

Conventional unmanned aerial vehicles power systems only have one MPPT controller to operate. And MPPT controller will be influenced by loss of solar arrays and multiple maximum power points. In this paper, an innovative topology of UAV power system is proposed as well as generating a related MPPT control strategy to keep output voltage increase slowly. Hardware circuit design is presented based on selection of power diode, input filter capacitance, output filter capacitance and parallel diode. A prototype of 1.2kW power supplies is implemented to verify the proposed topology and MPPT control strategies.

In this paper, a new method of determining boiler soot-blowing steam flow rate was proposed. By this method, three tests of unaccounted-for leakage rate of the unit thermal system should be conducted without soot blowing, and the unaccounted-for leakage ratio difference between arbitrary two tests should be within 0.10%. The average value of three unaccounted-for leakage flow rate test results was used as the final result of unit unaccounted-for leakage flow to determine the flow rate of soot-blowing steam. During the test period of power output and heat rate, the calculation of soot blowing steam flow rate took account of the result of unaccounted-for leakage tests and the water level change of condenser hot well, deaerator and boiler drum.

Particle systems involve numerous fields such as combustion, oceanography, photocatalysis, and atmospheric science, among others. In fact, most of these systems were in the form of multi-particle systems composed of different types of particles. In most previous studies, the influence of the type of element on radiative characteristic parameters was not considered, or the effective medium theory was adopted, which led to large calculation errors. In this paper, the differential-integration algorithm developed based on the Mie theory was used to calculate the radiative characteristics (extinction coefficient, absorption coefficient, scattering phase function, asymmetry factor) of a multi-particle system with non-uniform size distribution, and the Monte Carlo ray-tracing (MCRT) method was used to solve the radiative transfer equation (RTE). SiO₂ particles and polystyrene particles were investigated and subsequently divided into two categories: submicron particles (χ_>1) and nano particles (χ_>1) according to the size parameter. The radiative characteristics and spectral transmittance of particles with different volume fraction ratios and different particle sizes in the multi-particle system were also investigated. The results of the proposed method were compared to those of experimental tests to verify the accuracy of the algorithm. The maximum relative transmittance error decreased from 30.1% to 0.77%, and the average error decreased from 18.78% to 0.67%.

For the search and rescue work after the earthquake or the exploration of unknown areas, a photovoltaic-based intelligent search and rescue device was designed. A hardware platform for a car automatic driving system controlled by an STM32 single-chip microcomputer based on an ARM core is constructed, which consists of a photovoltaic auxiliary power generation module, a power supply module, a main controller module, obstacle detection, a motor drive module, a speed detection module, and a video transmission module. And constructed a software platform based on ARM core STM32F103 single-chip microcomputer controlled automatic control system. Finally, through the joint debugging of the hardware and software parts of the photovoltaic intelligent search and rescue equipment, the stability and feasibility of the system were verified, and the functions of photovoltaic-assisted power generation, manual control, autonomous obstacle avoidance, and video transmission of the car were realized.

Considering the thermal and electricity needs of users in the integrated energy system, in recent years, combined heat and power systems with micro gas turbines as the core have been widely used in integrated energy systems. How to coordinate and schedule heating and power supply in an integrated energy system is very important. In this paper, we take a micro gas turbine-integrated energy system (MGT-IES) as the research object, aiming at the uncertainty of heat load, we adopt a multi-scenario random planning method, while combining user heating comfort the degree of ambiguity and the thermal inertia of the heating system are considered. The indoor thermal comfort index is used to convert the heat load demand from the traditional curve to the interval, so that the heat load is elastic at each point in time, and finally it is established to be more in line with the actual optimal scheduling model. The case analysis shows that after comprehensively considering the uncertainty of the heat load side and the thermal characteristics of the heating system, MGT-IES can effectively reduce the operation cost of the optimized dispatching while meeting the user's heat load demand.

Due to the uncertainty of the energy supply and the power demand, the stability and economic performance of the integrated energy system has become a key problem. In this paper, economic model predictive control with augmented model was directly applied to optimize the performance index while responding power demand. Based on the prices of power and hot water, the economic objective function was designed and two modes of operation of heating have been studied which include providing domestic hot water and space heating. The simulation result shows, compared with traditional model predictive control, economic model predictive control could improve economic performance of system by 20% while providing domestic hot water, and showed similar performance while working on space heating.

In this article, we have optimized the total operational cost of combined cooling heating and power system (CCHP). This cost is further divided into three major parts, which are the capital cost of the equipment, fuel cost, and the grid electricity cost. The heat storage tank has also been used to store the excessive heat that can be utilized when needed. A genetic algorithm has been used for the optimization of the whole system. The decision variables chosen were 74. The optimization resulted in significant reduction in the total cost. The final results show that the cooling demand was significantly supplied by the Grid through the electric chillers because of higher coefficient of performance, while the power demand was met through the power generation unit. Results shows that the natural gas cost consumption is much greater then the grid and equipment cost.

Solar energy resource is highly rich in Inner Mongolia regions, and the customers utilized electric are scattered in the vast grassland. Thus, the distributed generation with its unique performance and high quality, has been developed rapidly in recent years. However, the large-scale distributed power supply has brought many unpredictable impacts when they are accessed to the distribution network, even seriously affecting the safe and stable operation of the distribution network. In this work, the technical barriers caused by distributed power generation to the grid-connected have been explored. In addition, the constraints and key influencing factors of distributed generation on distribution network have also been analysed and a safe and stable operation strategy to access distributed photovoltaic power supply into the network has proposed. The results here could provide a theoretical guidance for the rapid formulation and optimization of the distributed power accessing into grid network in Inner Mongolia power grid.

A new asphalt binder for road applications was prepared by mixing coal tar pitch and petroleum asphalt, and then modifying with compound modifier which was made by ourselves. Coal tar pitch and petroleum asphalt was 1:1 for weight. The modifier was made with epoxy resin, chopped carbon fiber which was modified by 3-Aminopropyltriethoxysilane (KH-550) and other auxiliaries. According to "Standard Test Methods of Bitument and Bituminous Mixture for Highway Engineering" JTG E20-2011, the properties of the modified asphalt (MA) were studied, and the best modification technology was mechanical shear of 3000r/min shear rate for 30mins at 110 °C, the amount of modifier was 5%. The properties of MA mixture were also researched, the performance of AC-20 mixture can meet the JTG F40-2004 "Specification for construction of highway asphalt pavement" in the relevant requirements. The oil-stone ratio was 4.7%. The requirement of dynamic stability was ≥ 800n/mm, the wheel tracking test showed the MA mixture exhibited a value of 1323n/mm, which meet the requirement. The MA mixture low-temperature property was studied by the beam bending test, the results indicated a higher value than the AH-70 mixture standard. The Freeze-thaw split test demonstrated the MA mixture water stability meet the requirement for asphalt. In all, a new asphalt binder for road applications was obtained by mixing coal tar pitch and petroleum asphalt, its properties meet the standard of AH-70 and its mixture. The modifier was added for 5% and the effect was best.

In semi-continuous anaerobic digestion, organic material feed sometimes may not be consumed completely in one day and it may considerably help to increase biogas production of next day. Such occurrence is called 'biogas accumulation phenomenon', which cannot reflect the real biogas production from next day's feed. In this test, first-order model was modified to solve this problem. Compared with first-order model, k values of modified first-order model had smaller relative standard deviation for each week with better fitting degree. Modified first-order model was then verified using food waste with different theoretical biogas production. Therefore, it can be concluded that the modified model can remove biogas accumulation phenomenon effectively. However, this model didn't perform well in methane production fitting. The modified first-order model was utilized to study the variation trend of biogas production from anaerobic digestion of food waste with increasing salt concentration in the reactor. Results showed that when salt concentration in reactor increased from 0.69 to 2.12 g.-L⁻¹, biogas production experienced increasing first and then deceasing. 0.98 to 1.27g-L.⁻¹salt concentration was more appropriate for biogas production (653-718L.-kg⁻¹ VS) and when salt concentration increased to 1.36-1.61 g.-L⁻¹, inhibition phenomenon began. Biogas production (363-420L.-kg⁻¹ VS) was further suppressed with 1.68-2.12 g.-L⁻¹salt concentration. At this time, the ratio of volatile organic acids to the total inorganic carbon (VOA/TIC) increased to 0.24-0.58, showing anaerobic digestion process was unstable.

Pumped storage unit as the most efficient energy storage equipment, it makes a great contribution to the development of renewable energy. The operating stability of pump turbine affects economical and safe operation of pumped storage plant directly, hence this study focuses on the transient process of pump turbine load rejection. Detached eddy simulation is adopted as turbulence model and dynamic mesh technique is used to achieve continuous guide vane closure. Internal fluid characteristics are presented based on the numerical analysis of inter-blade vortex and force of runner blades. The results show that:(1) Inter-blade vortex can be divided into two developing stages according to its location, which corresponds to the first and second half of guide vane closure respectively. (2) The incidence angle is the original reason that causes vortex in runner passage, which further development occupies the whole flow passage under the influence from centrifugal force and the interaction with the previous water. (3) The force distribution is aligned with the vortex zone, and the axial thrust keeps a downward tendency.

Aiming at the problem of serious switching loss in high-power and high-voltage occasions, the traditional LLC resonant network is difficult to adapt, the DC gain is difficult to obtain intuitively, and the voltage stress on the switch is too high, resulting in large switching losses and difficult selection of the switch. This paper uses a three-level full-bridge LLC resonant converter topology, the First Harmonic Approximation (FHA) is used to analyze the LLC resonant converter gain characteristics, and the parameter design ideas are given. A simulation experiment of a three-level full-bridge LLC resonant converter based on frequency modulation control is presented. The simulation results show that each primary side switch transistor can achieve zero voltage switching (ZVS), the secondary side diode realizes zero current switching (ZCS), and can obtain higher working efficiency, which verifies the feasibility of the design.

The clocking effect is widely recognized to have an important impact on the function of rotating machinery. The effect of the clocking position on the flow field and the hydraulic performance in a pump as turbine (PAT)with vane diffusers has been investigated and analyzed numerically. The results show the hydraulic performance of the PAT decreasing gradually as the diffuser blade near the tongue. Under optimal operating conditions, the maximum difference in efficiency for different guide vane positions is 2.2%. When the position of the tongue is equidistant from the two diffuser blades, the energy loss of the volute and the diffuser is minimized. And the flow field results prove that the timing position affects the flow field in the volute and diffuser to a certain extent, but has little effect on the impeller. In addition, this may provide ideas for the installation of PAT with guide vanes, and the diaphragm should be as far away as possible from the two adjacent diffuser blades.

In view of the large voltage harmonics and low power density of the low-power ultrasonic power supply, a low-power ultrasonic power supply based on the cascade buck technology is proposed. The converter of the power supply is composed of two buck units in cascade, and the output of the unit is forward Sinusoidal half-wave DC voltage waveform, and then commutated by the full-bridge inverter every half cycle to output sine wave AC voltage waveform, can significantly reduce the voltage harmonics of the ultrasonic power supply, reduce the inductance of the matching network, and improve the ultrasonic wave Power density. Through the combination of voltage and current phase detection and PI regulator, the tracking resonance frequency is controlled. By analyzing the system structure, working principle and control strategy of the ultrasonic power supply, modeling and simulation are carried out on Matlab / Simulink, and the feasibility and effectiveness of the scheme are verified.

There are mass data that contain important defect texts in the power grid enterprise, and they contain important reliability information. And the efficiency is very low to mine the exact information about the texts especially when the texts are in Chinese. Thus, the defect text mining technique based on the modified semantic framework is proposed. All texts are translated into English and use the text mining model based on the modified semantic framework, the defect texts are divided into a fixed pattern and the digital information can be extracted accurately. Take the transformer as an example, the first step is to establish the ontology dictionary and to separate the sentence and extract the texts' features. Then, the modified power semantic framework and the semantic slots are defined, and the slots filling method and the semantic framework construction process are discussed, which can automatically perfect the ontology dictionary by merging the word series. Finally, the researches of defect text mining results of statistical reliability are studied, and the results show that the proposed model and method is feasible and effective when applied to automatic classification and statistics of grid defect.

The electrical tomography technology is a multi-phase flow detection technology. This technology has the advantages of non-radiation, non-invasive and visualization, can be widely used in traditional energy field and new energy field. The permittivity and conductivity, as the basic electrical parameters of material, are closely related to the distribution of material in multiphase flow. However, in the actual multiphase flow, due to the non-uniform distribution of permittivity and conductivity in time and space, the accuracy and validity of measuring instruments are challenged. The main target of this research is to investigate the application of electrical capacitance tomography (ECT), electrical resistance tomography with voltage excitation (ERTv) and electrical resistance tomography with current excitation (ERTc) on the multiphase flow with complex permittivity and conductivity distribution. The final objective based on the above research is to provide suitable tomography modual for different multiphase flow process. The experimental results show that ECT is suitable for measuring dry gas-solid fluids. ERTv is better for measuring high water content gas-solid fluids and low conductivity gas-liquid fluids, while ERTc is better for measuring continuous phase conductivity gas-liquid fluids.

In view of the distribution network operation problems caused by many distributed generations integration to distribution network, and the increasingly serious peak valley imbalance in grid, this paper proposes a coordinated control system of source-network-load-storage based on virtual power plant technology, which is designed and implemented in the actual project. The system uses cloud platform technology and multi-energy complementary technology to realize coordination and optimization control mechanism between sources, network and loads in regional distribution network. The system is based on the distribution Internet of things cloud master platform. Through the virtual power plant technology, resources such as cogeneration, photovoltaic, wind, distributed energy storage, electric vehicles, flexible loads are aggregated to achieve coordinated and unified control, realize the optimal operation of multi-energy complementary. It can accept the control of the dispatching center, and participate in the power transaction of demand response. Based on the application scenario, this paper explains how to use virtual power plant technology to participate in demand response power transaction, and describes the transaction rules and processes. The system is beneficial to the safety and reliability of the distribution network. It can implement reasonable configuration and consumption of distribution generations. It can control controllable loads such as electric vehicle charging pile to participate in peak regulation of power grid, and provide strong technical support for the realization of demand response.

The DC voltage imbalance of a single-phase cascaded photovoltaic inverter will decrease the quality of output voltage. The general modulation method needs to add power balance control to restrain the imbalance and make the control system complicated. To address the issue, a modified Space Vector Modulation (SVM) method is presented in this paper. The modulation method combines the DC voltage control of each unit with the modulation method to achieve DC voltage control of each unit in vector selection, eliminating the need for additional power balance control, thereby simplifying the control system. The modified space vector modulation can not only make the DC voltage rapidly track the DC voltage instruction of each cell through vector selection but also ensure the quality of output voltage waveform when the DC voltage of each cell is imbalanced. The effectiveness of the modified SVM method is verified, and the simulation model has built by using MATLAB/Simulink.

To investigate the effects of the fuel material property on the temperature safety response characteristics of the new-designed open-cycled reactor with the air as the coolant, the geometric model of the annular fuel rod is built. The parameter model is developed based on the properties of the three types of ceramic material of nuclear fuel including the Uranium dioxide (UO₂), Uranium carbide (UC) and Uranium nitride (UN). The temperature transient response rule of the three kinds of fuel rods at the cases of reactor power step increase is obtained based on the fluid-structure coupling method. The temperature transient response characteristics of three types of ceramic fuel rods open-cycled reactor are analyzed. The numerical results reveal that the peak fuel temperature and the average fuel temperature increase significantly with the step increasing reactor power. The response time of the fuel rod with UC is the longest. The peak fuel temperature and the temperature difference of the fuel rod with UO₂ are the highest. The relative results can lay the theoretical foundation for the fuel material selection, structure design and the safety analysis of the open-cycled reactor.

So as to research impact of inlet temperature of gas cooler on the expression of carbon dioxide hot water unit, the ambient temperature was controlled at 15 °C, and the inlet temperature was adjusted. The exhaust temperature, heating capacity, and system heat exchange capability were calculated. Testing and measuring the change of exhaust temperature, outlet temperature of gas cooler, exhaust pressure, heat exchange capability. Based on simulink simulation tools, a calculation simulation platform of CO₂ heat pump water heaters was established, and a test bench of transcritical CO₂ heat pumps was built. In the experimental simulation, the inlet water temperature was increased from 15 °C to 40 °C, the simulation result of the exhaust temperature increased by 14.2 °C, the heating capacity decreased by 4.69 kW, the heat pump coefficient decreased by 0.66. In the experimental result, the exhaust temperature increased by 18.7 °C, the heating capacity decreased by 4.31 kW, heat pump coefficient decreased by 0.63. The research results can provide some guidances for the practical application and optimization of transcritical CO₂ heat pump system.

Fossil fuel combustion and automobile exhaust emissions are the main causes of the greenhouse effect. An effective measure to solve this problem is to convert carbon dioxide into green and clean energy. Photocatalytic technology is a green technology with important application prospects in the energy and environmental fields. At present, the catalyst has some defects, such as specific surface area is lower, the photoelectric-hole pair recombination rate is fast and the quantum efficiency is low. Therefore, effective photocatalysts have become the focus of researchers. In the paper, WSe₂ was successfully prepared by the hydrothermal reaction using two different reductants and solvents, and the XRD, UV-Vis DRS, N₂ adsorption-desorption tests are adopted for characterization of prepared sample. The XRD, UV-Vis DRS and BET characterization results show that the WSe₂ samples prepared with two reductants both contain pure-phase WSe₂, and the location distribution of main diffraction peaks is consistent with that of hexagonal WSe₂ (JCPDS card, PDF#38-1388); the prepared WSe₂ presents photo response within the range of 200-700nm, but compared with WSe₂ (NaBH₄), the light absorption intensity of WSe₂ (N₂H₄.H₂O) is significantly enhanced; compared with WSe₂ (NaBH₄), the specific surface area of WSe₂ (N₂H₄.H₂O) is bigger, which are 3.4 m^2.g⁻¹ and 3.0 m² g⁻¹, respectively. After photocatalytic reaction for 12h with the catalyst of two different WSe₂ (N₂H₄.H₂O) and WSe₂ (NaBH₄), WSe₂ (N₂H₄.H₂O) shows great photocatalytic activity, and the overall yields of CH₃OH are 327.13 μmol g⁻¹cat and 46.32 μmol g⁻¹cat, respectively.

In order to verify the compensation effect of high voltage static var generator. The system structure of cascaded H-bridge is adopted. The bipolar CPS-SPWM and monopole frequency doubling CPS-SPWM modulation modes are compared by simulation. The instantaneous reactive power detection principle is derived theoretically. The reactive power can be compensated quickly by using monopole frequency doubling CPS-SPWM modulation mode and instantaneous reactive power detection. Using Matlab/Simulink to build 10kv High-voltage SVG, the fast and accurate reactive power compensation is realized under the switching of inductive reactive power and capacitive reactive power. The reliability of the design is verified by simulation.

In the distribution network containing distributed generators (DG), both DG and capacitors can be adjusted for reactive power, and there is a strong complementarity between the two. If the reactive power compensation ability of each grid-connected DG can be fully utilized, it will effectively reduce the voltage fluctuation and the number of equipment actions, which will help to improve the operation level of the distribution network. In this paper reactive power optimization of distribution networks containing distributed power sources has studies. An improved evolutionary programming (EP) method is proposed to solve the optimization goal, using a variable step-size evolution method and optimization strategy with small population and high convergence accuracy. The algorithm improves the random dynamic step method. In different stages of optimization, different step sizes are used to improve the optimization effect. At the same time, considering that some wind farms are equipped with AVC and some wind farms are equipped with capacitor banks, the evolutionary operator is improved. The operator evolves directly on the integer, so it is easier to find the global optimal solution. This paper has used IEEE33 bus system to verification. Results show that the DG can reduce active power loss in distribution network and ameliorate the voltage level. Meanwhile, the improved evolutionary programming method has good optimization effect, fast convergence speed and high search efficiency.

For the low-temperature SOFC/GT combined cycle system used to recover the SOFC cathode intake air by using turbine exhaust gas circulation, a simulation model of the combined cycle system was established based on the lumped parameter model of SOFC, turbine, compressor and preheater. Some experimental data have verified the validity of the zero-dimensional model of SOFC. The system simulation results show that the air intake pressure caused by the air recirculation does not completely depend on the outlet pressure of the compressor. When the outlet pressure of the compressor is between 0.2MPa and 0.5MPa. The intake pressure of the SOFC will decrease to varying degrees, and it depends on the proportion of the exhaust gas recirculation. The compression ratio is not related to the output power and efficiency of the SOFC. Increase in compression ratio will reduce the output of the turbine, resulting in a reduction in the overall efficiency of the system.

For the SOFC/GT combined cycle system where the preheater is arranged behind the turbine, the thermodynamic model is used to describe the compressor, turbine, and preheater, and the zero-dimensional model is used to describe the fuel cell. The performances of the low-temperature fuel cell combined cycle system and the medium-temperature fuel cell combined cycle system are studied. The results show that the medium-temperature fuel cell system has higher power and efficiency, because the efficiency of SOFC is higher than that of gas turbines under most operating conditions. Increasing, power and efficiency tend to decrease. The increase of fuel utilization rate leads to an increase in the overall efficiency of the system. The higher the fuel utilization rate, the more obviously the cycle efficiency is affected by the SOFC, and the faster the decline with the increase of fuel. When the fuel consumption is high and the current density of the SOFC is high, low cell fuel utilization is beneficial to cycle efficiency.

In order to improve the photovoltaic penetration of the power system, an optimal scheduling model of pumped storage system with large-scale photovoltaic based on carbon trading is proposed in this paper. Firstly, based on the analysis of low-carbon economy, the stepped carbon emission trading mechanism is introduced into the economic dispatch of power system. And in order to improve the calculating efficiency, an improved K-means clustering algorithm based on maximum and minimum distance criterion is proposed to cluster the photovoltaic power generation scenarios. Then the optimal scheduling model is established. Take the lowest comprehensive operation costs of the system as the objective function, and the operation economy and low carbon of the system are considered. The pumped storage is used as energy storage for peak load shaving in the generation system. At last, an improved IEEE RTS-96 system is taken to finish the case study, and the simulation results show that the model proposed in this paper is reasonable and effective.

The short-circuit capacity of the bus is a key parameter required for the operation and control of the power system. Online measurement of the short-circuit capacity is crucial for the observability and controllability of the power grid. In this paper, it is proposed that the bus voltage disturbance can be caused by switching on and off the parallel capacitor. According to the voltage disturbance, the on-line measurement of the short circuit capacity of the power grid can be performed. Based on the circuit model of the substation, using the substitution theorem and superposition principle of the linear circuit, the accurate calculation method of bus short-circuit capacity measurement is derived. It is revealed that the phase change of the voltage vector caused by the capacitor switching is the key factor affecting the measurement accuracy. It breaks through the approximate formulas of previous studies. The proposed measurement method has high accuracy; an iterative calculation method for the phase difference of the voltage vector is proposed. The method is more convenient and reliable than direct measurement. Based on MATLAB / Simulink, the substation bus and online measurement model are established. Simulation analysis of various scenarios shows that the proposed method has a measurement error of less than 1%, which is technically easy to implement and practically promote.

Phase change materials (PCM) are wildly investigated and used in the fields of thermal energy storage and thermal control of electronics. Numerical simulation is an important method in the research, development, analysis and design of PCM based systems. At present, there are two main numerical methods for the simulation of solid-liquid phase transition problems with natural convection: the finite volume method (FVM) based on macroscopic scale continuity equations, and the lattice Boltzmann method (LBM) based on mesoscopic scale lattice Boltzmann equation. In this paper, the calculation characteristics, speed, efficiency, and accuracy of the two numerical methods are compared, with the classical solid-liquid phase change heat transfer experimental results as benchmark reference. The results obtained in this paper can be used as valuable reference for the selection and use of numerical simulation methods in the study of solid-liquid phase transition problems.

The conjugate heat transfer from in-furnace combustion to in–tube supercritical fluid has been numerically investigated in this study. The mathematical model of the conjugate heat transfer process has been constructed. The effects of the abnormal heat transfer phenomena of supercritical fluid in tube and combustion status change in the furnace on the conjugate heat transfer process were analyzed. The results demonstrate that the Renormalization-group (RNG) model has better prediction ability. The Abe-Kondoh-Nagano (AKN) model will have an over-prediction problem for the abnormal heat transfer. The RNG model is also more accurate in simulating the combustion process in the furnace.

According to the characteristics of huge data, high control precision and fast response speed of the energy storage station, the conventional monitoring technology can not meet the practical application requirements. In this paper, an integrated monitoring system for energy management of energy storage station is designed. The key technologies, such as multi-module integration technology, centralized energy management control technology, high concurrency group control technology based on IEC61850 and internal interaction mechanism based on User Datagram Protocol, are described in detail. Relying on the project site of Langli energy storage station, the secondary system architecture of the energy storage station is simplified, the stability of control operation and the fast response ability of power conversion system group are improved, and the reliability of output power of the energy storage station is guaranteed.

3D non-equilibrium molecular dynamics simulations are performed to investigate the friction characteristic of Fe-Fe tribopair system under third medium condition. A Fe-Fe sliding simulation model with the soft third medium (Cu nanoparticle) is built. The Friction force, evolution of the structure of interface and the temperature profiles of the sliding system are obtained. The influence of the sliding velocity to the temperature and structure change under third medium is investigated. The influence of Cu nanoparticle to the microstructure evolution and change of the friction characteristic is extremely concerned. The results show that the Cu nanoparticle can decrease the friction force and average temperature under the relatively low velocity (25m/s). However, under high velocity (150m/s), the positive effect is not obvious. A Cu nano-film would form on the surface, which is useful for weakening the destruction of the interface, and protecting the sliding blocks. Under high velocity, a mixing layer would be formed in both two cases (with or without Cu nanoparticle).

Both electric vehicle PMSM drive system and grid connected photovoltaic (PV) power generation need voltage source inverter (VSI). The dead time should be set properly when the power switches are turned on and off in the same bridge arm of VSI. During the dead time, the load is out of control, which will cause the abnormal output voltage amplitude and phase. However the influence of dead time on the output fundamental voltage phase has not been paid much attention to and studied. Firstly, in the paper, the phase shift of output fundamental voltage caused by dead time is simulated and analyzed for three-phase VSI - resistance inductance series (RL) load system under several conditions such as variable switching frequency, modulation index, output fundamental frequency and dead time. Secondly, take three-phase VSI - permanent magnet synchronous motor (PMSM) drive system for instance, the simulation analysis of output fundamental voltage phase shift and rotor positioning error caused by dead time are also performed, and an off-line method to compensate the fundamental voltage phase based on αβ coordinate is given. The above work provides a reference for further understanding the influence of dead time on fundamental voltage phase shift in VSI, so as to improve the monitoring and control precision of electric vehicle drive system. The analysis approach can be applicable to the grid connected photovoltaic (PV) power generation PMSM servo system.

The conjugate heat transfer from in–furnace combustion to in-tube supercritical fluid has been numerically investigated in this study. The mathematic model of the conjugate heat transfer process has been constructed. The effects of the heat transfer phenomenons of supercritical fluid in tube and combustion status change in the furnace on the conjugate heat transfer process were analyzed. The results show that the RNG (Renormalization-group) model can better simulate the heat transfer process in the tube and the combustion process in the furnace than the AKN (Abe-Kondoh-Nagano) model. The difference between the two turbulence models for the furnace simulation focuses on the distribution in the high temperature region and the region of the recirculation region.

In the process of sailing, the frictional resistance of underwater objects must be reduced, which is of great significance for improving speed, range and saving energy. Based on the inspiration of the shark breathing process, this paper simplified the water spray process from the external bronchial slit of the shark breathing to the cross-flow lateral jet process. By establishing a numerical model, the influence mechanism of the jet on the flow resistance was studied, and by analyzing different jet velocities, the change of viscous resistance reveals the influence of jet velocity on viscous resistance. The results show that the side jet can reduce the boundary layer on the surface of the object, thereby having a drag reduction effect, and the drag reduction rate can be about 10%. In addition, as the jet velocity increases, the drag reduction effect is enhanced, and at the back of the jet port the vortex is formed, the outlet pressure is reduced, and the drag reduction effect is strengthened. At the same time, the study found that the arc-shaped jet port is more conducive to the reduction of resistance.

In order to reduce energy consumption of commercial and public buildings, a series of policies has been implemented in Shanghai area. And retrofitting of inefficient commercial and public buildings serves as one of the main measures. However, there is little study about the effect and economic analysis of energy saving retrofitting, which hinders the popularizing of energy saving retrofitting. Under the sponsorship of the government of Shanghai and World Bank, a typical office building in Changning district of Shanghai was studied about whether it could be retrofitted into a nearly zero energy building through a series of passive and active technologies. During the design stage, based on energy consumption simulations, it was found that nearly zero energy building could save 37.1% energy compared with baseline building. Among the adopted technologies, high-efficiency lamp and photovoltaic system had a relatively higher energy saving ratio, which were followed by high-efficiency cooling and heating system, natural lighting and envelope insulation. Natural ventilation had the least energy saving ratio. By one-year field monitoring of energy consumption after building retrofitting, it was found that the retrofitted building was able to control the CO2 emission per unit area to be less than 25 kg/m2 · a, which met the goal of nearly zero energy building. And the incremental cost per unit area of nearly zero energy building is ￥1553 compared to baseline building. High efficiency lighting is the most cost-effective technology. The conclusions drawn in this study could provide reference for similar retrofitting projects in Shanghai area.

This paper proposes a distributed optimization method to solve the problems of centralized optimization and centralized management of a microgrid. Also, the distributed optimization solution method upgrade to a process of distributed iterative solution and optimization, which can solve the distributed optimization problem of a large microgrid cluster. According to iterative calculation, accord the augmented Lagrange function supports the centralized optimization problem divided into corresponding subproblems, and the penalty factors of interconnected variables considered to adjust the consumption of local resources, to make microgrid cluster (MGC) more flexible. In particular, the framework of multi-verse consistency and model predictive control (MPC) can help the global optimization reach the optimal quickly. In this paper, the simulation is solved by Gurobi commercial solver in MATLAB. The results show that the proposed method needs only a few iterations to achieve global optimization, and the effectiveness of plug and play proved.

In this paper, a three-dimensional microscopic model of the solid oxide fuel cell (SOFC) anode is established based on the SOFC anode microstructure reconstructed by Nano-CT, and the characterization parameters of the electrode are calculated. The electrochemical reaction is defined on the three-phase boundaries of the microstructure, and the polarization characteristic at different temperatures is explored. Results show that the anode polarization loss increase with the increase of temperature. The activation loss and the ohmic loss are of the same magnitude and occupy the main part of the total polarization loss. The pore microstructure directly affects the gas transfer in the anode, and there is a large mass transfer resistance in the small throat, which causes obvious concentration polarization loss and affects the activation loss. Due to the uneven microstructure, the electrochemical reaction rate of the electrodes at the same depth is not consistent. The closer to the electrode-electrolyte interface, the more obvious the unevenness of activation polarization and concentration polarization.

This paper makes innovative research on developing a data-driven control strategy under the Energy Internet of Things architecture. On the one hand, the platform aims to provide data representation and interpretable analysis for different stakeholders (end users, construction operators or managers) to realize the flexibility and scalability of the platform; on the other hand, it can improve the thermal comfort and also reduce the power consumption of buildings. However, to process vast amounts of data, it is critical to select appropriate control methods and design optimization issues. Data-driven predictive control (DPC) is a control technology that replaces model-based predictive control (MPC). When applied to complex building operations, MPC is implemented by using the control-oriented data-driven model. The key to DPC technology is the use of CatBoost algorithm, which is highly interpretable and easy to be operated by stakeholders. This paper chooses TDNN, LightGBM, and CatBoost to compare and analyze building energy consumption. Numerical simulation results show that the CatBoost algorithm's performance is better than other algorithms, and the complexity and implementation cost is significantly reduced.

In this experiment, the switchable evaporation and condensation horizontal single-tube heat exchange experiment platform is designed. And the equipment selection and construction of the experiment platform is completed through the design calculation. The experimental results show that the thermal balance error of the test section of the experiment platform is less than 15%, especially the condensation and evaporation experiment of R22 in 12.7 mm copper tube, and the evaporation experiment of R410A in 9.52 mm copper tube, the thermal balance error of the experiment is less than 5%. The experiment platform can realize heat exchange experiments with different refrigerants, and the test section of the experiment platform can be standardized replacement of tube types according to research needs.

With the large number of construction and commercial operation of trough solar thermal power station, the performance test standard and test method of trough solar power station are still missing and imperfect. For the heat storage heat exchange system of trough type solar thermal power station, the index system of heat exchange efficiency, heat storage time and heat collection efficiency are constructed, and the work contents of performance test and technical index are improved. Learn from the idea and concept of performance acceptance test of thermal power generation equipment system in power industry, combined with many years of relevant work experience. It is expected to bring reference and guidance to relevant technical personnel and peers.

In order to solve the problem of building energy loss and actively respond to the implementation of the national energy conservation and emission reduction policy, this system, according to the international standard of vacuum glass JC/T1079-2008, combined with the development status and production demand of the measuring instrument, developed a set of instruments that can meet the design requirements to quickly and accurately measure the heat transfer coefficient of vacuum glass. At the same time, the constant pressure measurement conditions are put forward and implemented on the basis of the system. The circuit, software and mechanical structure of the system are studied and designed. Through the above design, the design and test of the vacuum glass heat transfer coefficient measuring instrument are completed. The experimental data show that the measurement error is 0.34% under the condition of adopting effective control strategy, which is about 16 times lower than the measurement error of low-end control method, which is 5.6%. The conclusion shows that the instrument can be used to measure the target more accurately, which is of economic and practical significance.

Based on the smart dispatching support system and the smart substation system, and based on the functional requirements of the dispatching center to the substation, a source maintenance plan of integrated sharing of model, graphical and communication points between the smart substation and the dispatching center is proposed, and the traditional source maintenance process is optimized according to the actual requirements. According to the plan, an intelligent debugging platform for the whole process of the automation system is developed, and a new mode of smart substation access dispatching center is explored. In this paper, the key technologies of the debugging platform are introduced from the aspects of primary equipment model transformation, primary equipment and measurement association, automatic generation of RCD file, and online master sub - station communication point checklist technology.

Compared with traditional controllers such as PI based on classic control theory, the article applies passive control (PBC) theory to the design of three-phase LCL grid-connected inverter controllers. The mathematical model of the system based on Euler-Lagrange (EL) is established, and the damping method of the trap is used to suppress the resonance spikes generated by the system, so that the system meets the requirements of grid connection. The simulation results verify the feasibility of the scheme.

This paper reports a new process of using phosphate rock as the precursor to prepare a high performance catalyst for glycerol carbonate synthesis. The reported technical route will create a new opportunity to synthesis the active chemical intermediate that can be used for energy generation. Three important preparation parameters were investigated to find out both singular and binary effects upon the statistical significances of prepared glycerol carbonate conversion using response surface methodology (RSM) approach. The optimal condition with the goal of maximizing the glycerol carbonate was set and achieved. The obtained catalyst prepared at the optimal condition was characterized. The proposed process offers a rosy prospect for high value conversion of colossal by-product phosphogypsum generated from phosphorous acid manufacturing industry.

The new type of nuclear power plant adopts once-through steam generator (OTSG) which can supply steam to the turbine, control and operation of OTSG is different from the traditional natural circulation steam generator, the control strategy of the traditional natural circulation steam generator is not applicable to OTSG. In order to meet the demand of the general operation of the integrated reactor, the operation control of OTSG is put forward. The paper proposes a double const control strategy that the average temperature of the primary circuit coolant and the secondary circuit steam pressure are kept constant, also proposesa coordinated control strategy considering reactor and turbine as a whole. The control strategy is different the traditional control method. In order to verify the control strategy, simulation experiments are carried out in a full-scale simulator system. The simulation results show that the proposed control strategy of OTSG in integrated reactor to meet the load demand, also can effectively guarantee the dynamic characteristics of pressure steam generator and related parameters of OTSG.

In this paper, a test bench was built to study the thermal performance of three typical air collectors. Based on the test data, this paper conducted a comprehensive study on the physical and economic performance of the solar air heating systems including indoor temperature, solar energy guarantee rate, investment payback period and life cycle cost, and gave recommendations for their applications. The research showed that under the specified air flow rate range, the efficiency of the three typical collectors all reached above 45%. When the flow rate increased twice, the efficiencies of the V-groove collector, S-type spoiler collector, seams penetration collector were increased by 16%, 20%, 19%, respectively. This research recommended the ideal flow rate for solar air heating in China was 36 m³/(h.m²) ~ 54 m³/(h.m²). The simulation results in15 typical cities showed that the solar energy guarantee rate was generally above 20%, and in more than half of cities the solar energy guarantee rate reached 30% or above, with the highest in Lhasa, reached 62%. Economic analysis indicated more than 70% of the cities in northern China have a simple payback period of less than 6 years. The results indicated that solar air heating technology not only has a wide range of adaptability but also yield great financial benefits in northern China. This paper will have a significant impact on guiding the application of solar air heating in rural areas of China.

The renewable energy sources such as wind power and solar energy are widely connected to the current power network. The proportion of the renewable resources to the entire energy sources in the power grid is increasing. Since wind power and solar energy are intermittent, which have more uncertain factors, power grid operation is being impacted by generation of the renewable energy sources. Especially in the area of power balance and dispatch. Severe power imbalance, which causes the huge frequency deviation, will lead to the stability of power system. Therefore, it is very important to deal with the uncertainties of renewable energy. The existing deterministic approaches are not sufficient to deal with the uncertain factors. This paper analyzes the effect of renewable energy uncertainties in power grid operation based on the fuzzy theory and probabilistic methods. The steady-state security analysis is taken as an example to handle renewable energy uncertainty in power grid operation.

More and more network and provincial companies within the State Grid have adopted the "n + 1" architecture, that is, the deployment of production control at the regional and municipal levels, and the centralized deployment of information management at the provincial level to build the distribution automation master station system. The main station system of information management regional can independently evolve into the distribution cloud main station. In response to the construction trend of "n + 1" architecture, an integrated scheme' of distribution automation master station system based on "n + 1" mode is proposed, and it is verified and analyzed on the new generation of distribution master station system constructed by State Grid Ningxia Electric Power Company. The verification and analysis on the above show that this integrated solution can solve the problems of cross-regional data synchronization and distributed data storage based on the "N+1" mode of the power distribution master station system, while avoiding the repeated construction of the information management area. At the same time, this construction mode can reduce operating costs, improve the efficiency of distribution network data utilization. At present, this scheme has been applied in Sichuan, Inner Mongolia, Jiangsu and Shanghai Electric Power Company, has a strong demonstration.

In power systems with voltage levels of 66kV and below, the bus potential transformer (PT) burnout accidents frequently occur. Based on the harmonic balance method, this paper analyzes the ferromagnetic resonance mechanism, and analyzes the fault waveform recorded by the fault recording system in the 66kV substation, and obtains the possible cause of the accident. The PSCAD/EMTDC software was used to build the electromagnetic transient model, and the PT burnout process was restored. It is concluded that the main cause of the accident is the ferromagnetic resonance overvoltage caused by the saturation of the PT iron core. Three solutions are also proposed, the PT primary side neutral point ground by nonlinear resistance, open triangle of PT short-time access a little resistance, and PT with better excitation characteristics are selected. The feasibility of the solutions is verified by simulation.

Solid oxide fuel cells (SOFCs) are promising and efficient energy conversion devices. The modeling method was widely used to study characteristics of SOFCs due to limitation of experiments. Values of material properties such as porosity, tortuosity and pore radius are required information in modeling. Current modeling works usually employ material properties used in the literature, which are not exactly measured and the values vary in wide ranges. However, inappropriate selection of material properties can result in incorrect modeling results of SOFCs. In this study, a one-dimensional model of SOFCs was established to analyze the effects of different material parameters on the modeling results. A parameter sensitivity analysis was also conducted to determine the most influential parameters on the polarization curve. The results provide a reference for selection values of SOFC material parameters. This work can also be used as a guideline to fit the experimental polarization curve in numerical simulations by adjusting appropriate material parameters.

At present, China has overtaken the United States to become the world's largest new energy vehicle market. Due to differences in developmental trajectory, developmental mode, and charging standards, China and the U.S. have common interests and the foundation for cooperation, which can work together for a win-win development. Charging interoperability is the basis for ensuring charging safety and interchangeability of electric vehicles. This study examined and compared the differences between China and the U.S. in the standards for conductive AC charging of electric vehicles. The requirements for a control pilot circuit, proximity circuit, current capacity, and charging-state transition timing were analysed. Hierarchical and layered interoperability test cases based on GB/T 34657 and SAE J2953 series were presented. A dual interface interoperability test system was constructed and used to verify the test method rationale. The results provided a mutual inspection solution for AC charging equipment between China and the U.S. and accelerated global application and promotion of the electric vehicle industry.

Due to the insufficiency of actual fault samples, the machine learning based fault classification models of the power lines in smart grid are generally trained using the simulated fault samples acquired from software, such as Matlab/Simulink. Yet, the fault features of actual and simulated fault samples are different, and the existed methods might not be valid or accurate enough in classifying the fault types of actual power lines. Thus, a new fault classification model for actual power lines in smart grid based on deep-adversarial-transfer learning is proposed. Firstly, the conditional generative adversarial network (CGAN) is applied for the augmentation of actual fault samples, so as to increase the data amount to some extent. Then, the loss function of convolutional neural network (CNN) is resigned based on transfer learning, and a new fault classification framework based on improved CNN (I-CNN) is proposed. The I-CNN based model is trained using both adversarial and simulated samples, and can make the distrubution of both catergories of samples features closer, thereby achieving to classify the fault types of actual power lines. To verify the method validity, the real-world power line is used for case study. The results show the effectiveness of the proposed method.

The hybrid modular multilevel converter (hybrid MMC) can realize DC fault ride-through based on the capability of overmodulation and can continue to output reactive power to AC side during the fault, which can speed up the recovery of DC grid power after the fault is cleared. This paper improves the control strategy of DC fault ride-through. During the bipolar short circuit on the DC side, hybrid MMC blocks the short-circuit current of the DC side by adjusting the reference value of DC voltage dynamically. Moreover, the average value of the sub-modules is introduced into the active current controller to maintain the balance of the sub-module voltage. Then, the performance of the improved strategy is verified by MATLAB/Simulink simulation model.

The thermoelectric generation system (TGS) has many advantages such as clean, no mechanical vibration and high reliability. When TGS is connected to the power grid, it requires that the frequency and phase are same as the power grid. It will take a number of working periods for the response time under the traditional method. A frequency and phase lock method with FIR filter will be introduced in the paper. It is based on the Capture and EPWM module of TMS320F28335. The phase lock can be carried out in one period. And the working frequency of TMS320F28335 is 150MHZ. Therefore, the speed of the whole operation is fast. The experimental results show that the method is feasible.

China originally planned to use fuel ethanol gasoline nationwide in 2020, and taking corn as an important raw material of ethanol gasoline, this paper analyzed the life cycle cost model of corn fuel ethanol gasoline and traditional gasoline from production to consumption, including internal and external cost calculations. The internal cost is the actual cost of the industry chain, while the external cost is converted into the cost value by examining the environmental impact of pollutant emission levels in each stage of the life cycle of ethanol gasoline production. Based on this model, by selecting the project data of specific regions and manufacturers in China, it can be calculated as follows: The main links affecting the internal cost of ethanol gasoline production are crude oil procurement cost, refinery and ethanol plant construction cost; The main influencing link of external cost is the emission of ethanol gasoline combustion, including the fuel, power and other energy consumption factors in the production of ethanol and gasoline; The cost can be optimized from the perspective of production technology, technological process, energy material consumption and various labor costs. Assuming E10 is used in the whole Chinese market, the empirical results are as follows: among the pollutants produced by the use of ethanol-added gasoline in the whole region, CO₂ emission reduction is the largest, exceeding 53 million tons, followed by CO and wastewater emission reduction of 1.78 million tons and 1.58 million tons respectively. In terms of the conventional gasoline, the CO emission reduction of about 20% is the largest, followed by about 17% reduction of HC, about 15% reduction of SO₂ and about 9% reduction of CO₂ respectively. These results show that the promotion of ethanol gasoline (E10) usage in China has a considerable reduction effect of emission if the availability of raw materials are sufficient. The life cycle external cost of ethanol gasoline is 11.45%, lower than that of conventional gasoline. In 2019, China's fuel ethanol production capacity was 4.15 million tons, and the actual production was about 3 million tons. Assuming that all of it were used to produce E10 ethanol gasoline, compared with traditional gasoline consumption, the emission reduction benefit of E10 gasoline would be nearly $84.7 million.

NaSn₂(PO₄)₃ hard bulk materials were successfully obtained by low-temperature calcination (~600 °C) from hydrothermally synthesized sols without a powder-press or sintering at high temperature. A hydrothermal reaction was performed at 250 °C for 5 h using an aqueous solution of NaOH, an aqueous solution of SnCl4, and H₃PO₄ as starting materials. The ratio of the starting materials was changed, and the range in which NaSn₂(PO₄)₃ was formed was investigated. As a result, the sample hydrothermally synthesized under the synthesis conditions of Na: Sn: P = 2.75: 0.50: 1.75 was produced as a white sol in a Teflon container. In order to remove Cl from this sol, an immersion treatment with deionized water was performed. After immersion treatment for 3 h, and calcination at 600-900 °C, it was possible to obtain the target substance NaSn₂(PO₄)₃ as a hard bulk material.

Through the water model experiment of oxygen-enriched top-blowing bath smelting, the effects of factors such as gas flow, lance position and liquid height on the bubble size distribution and liquid splash height during top blowing process of waste circuit boards were studied. The results showed that, the mixing effect worked best when the lance blew in the center of the molten pool. With a suitable increase of the gas flow, the impact of bubble refinement in the molten pool can be optimized. At the same time, the liquid splash, slag entrapment and liquid level fluctuation were aggravated. Appropriately increasing the liquid height can inhibit liquid splash to a certain extent. Considering the effect of bubble refinement and liquid splash height, the optimal experimental conditions of this experimental system were as follows. A straight barrel lance with a diameter of 15mm was installed in the center of the furnace body, the liquid height was 80mm, the lance submersion depth was 40mm, and the gas flow was 7.48Nm³/h.

Conventional least squares finite element method for incompressible flow does not enforce mass conservation in pointwise, i.e. the velocity field is not exactly divergence free. In this paper, we present a pointwise mass conservative least squares isogeometric analysis for the Stokes problem. The method utilizes high order smooth basis functions generated from non-uniform rational B-spline (NURBS). Pointwise divergence free velocity field is defined using stream function on each patch of computational domain. Velocity boundary conditions and cross patch continuity are enforced in least square sense. Numerical results are presented for flow past a large circular cylinder in a channel and flow over a backward facing step. The results show improvements on local and global mass conservation.

Cold compressor (CC) was adopted to pump saturated liquid helium to obtain subcooled helium. In the Experimental Advanced Superconducting Tokamak (EAST) system, cold presses were studied and would replace the oil ring pump. The cold compressor processing and installation had been completed, and it had been tested by cold nitrogen gas. For cold compressors, testing at low temperature was essential, but the real working condition of low-temperature helium gas had great risks for large helium cryogenic system. Therefore, an independent cold nitrogen test system was an economical solution. In this work, numerical simulation and quantitative analysis method were used to investigate the flow field around different tip clearances and mass flow by CFD at liquid nitrogen temperature, and they were validated by experiments. When the tip clearance was increased by 0.1mm, the pressure ratio dropped 0.27% and the polytropic efficiency dropped 0.82%. To a certain extent, a larger tip clearance could improve the surge condition and had little influence on the efficiency. Therefore, in the design and operation, the tip clearance could be appropriately increased.

We present an enhanced micro-energy harvester design that couples a thermoelectric module to a heat storage unit formed by a Phase Change Material embedded within a metallic foam. The effect of the thermal resistance between the thermoelectric material and the ambient is investigated through an effective heat transfer coefficient. A case study is analyzed to transform daily thermal fluctuations into electricity during a full day on ground conditions in a Southern Hemisphere typical winter day, using hexadecane as PCM and aluminium as metallic foam. For base PCM as a heat storage unit, the micro-harvester generates 0.01 J after a full day of operation. However, the metallic foam multiplies the electric energy production: from 0.23 J for ∈ = 0.95 to 0.49 J for ∈ = 0.85. Importantly, the relative boost in electric energy production is robust across a wide range of thermal resistance loads.

The large-scale wind power integration into power system brings great impact on the grid voltage stability. In order to reduce the influences of grid-connected wind power on the power system and improve the safety of wind power integration, it is necessary to conduct research on reactive power compensation configuration of wind farm integration. Firstly, based on the actual situation of wind power project, the principle of reactive power compensation configuration is studied. Secondly, a theoretical calculation method of reactive power compensation configuration is proposed. On this basis, combined with the practical 300MW wind farm project, the reactive power compensation configuration example is analyzed. Finally, through the modeling and simulation by power system analysis software package (PSASP), the accuracy and effectiveness of the calculation method proposed by this paper are verified. This paper put forward a reactive power compensation configuration method which is applicable to all wind farms connected to the power system. This provides important support for voltage stability in the wind power integration project.

In view of the microgrid random optimization scheduling problem, this paper proposes a microgrid online optimization algorithm based on deep reinforcement learning. By using the approximate state-action value function of the deep neural network, the action of the battery is discretized into the decision variables output by the neural network, and then the remaining decision variables are solved by nonlinear programming and the immediate return is calculated. The optimal strategy is obtained by using the Q-learning algorithm. In order to make the neural network adapt to the randomness of wind, photovoltaic and load power, according to the wind, photovoltaic and load power prediction curves as well as wind, photovoltaic and load prediction errors, Monte Carlo sampling was used to generate multiple sets of training curves to train the neural network. After the training is completed, the weight is fixed and the real-time action value of the battery is output according to the real-time status of the microgrid, so as to realize the online optimal dispatching of the microgrid. Compared with day-ahead optimization results under different fluctuations of wind, photovoltaic and load power, the effectiveness and superiority of this algorithm in online optimization of microgrid are verified.

This study involves a new hybrid modeling method for finite element-neural network complex dynamic systems. Dynamic modeling of components with linear-elastic properties is obtained by using the finite element method (FEM) in complex dynamic systems, while the dynamic characteristics of the nonlinear elements were described by neural networks. They may be connected by force or displacement to generate the dynamic hybrid model of the entire system, which effectively combined the characteristics of finite element modeling and neural network modeling. The relevant characteristics include clear physical structure, high modeling precision, small network scale, and fast training speed. The mode reduction method is applied to reduce the computational load for the response prediction of the hybrid model. Simulations of hybrid modeling for dynamic characteristics in the vibration isolation systems of steel wire rope are performed to demonstrate the effectiveness of the proposed method. This result provides an effective approach for modeling the complex dynamic system with an elastic structure, which includes nonlinear element components.