Line electrical transmission damage identification tool in distributors electrical networks

In the paper showing that one of the main way for Ukraine electric power industry evolution is electric power networks and systems improvement and construction considering Smart Grid concept. The main idea of Smart grid is the reliable, energy-efficient and high-quality energy supply system. To implement the idea, it is necessary to create a high-performance information and computing infrastructure. The main components of Smart Grid is emergency mode diagnostics and damage monitoring. Providing fault diagnostics and fault monitoring can improve the power supply reliability and quality to consumers. So, the task of quickly and accurately determining the place of damage is important. In the article showing that emergency detection tools in sections of both cable and overhead electrical networks it’s a way to improve efficiency of the networks. The diagram of the placement of damage indicators on the section of the electrical distribution network is presented, which allows determining the direction of the search for the location of the damage. A comparative analysis of measuring current transformers of optical and electromagnetic type was carried out. It is shown that a significant number of advantages of optical measuring current transformers, which can be used in damage indicators, can be provided by measuring current transformers of the electromagnetic type. Creating fault indicator based on the Smart Grid concept lets do to reduce searching time for the cause and location of an emergency situation to a minimum. In this concept application fault indicator in energy grid ensure it connection to operating overhead and cable lines without removing voltage by connecting the output of the secondary winding of the measuring current transformer of the detachable design to the measuring converters directly placed near the current measuring transformers with the help of a mechanical spring fastener. A block diagram of a specialized information-measuring system with a damage indicator was created, taking into account the requirements of the Smart Grid concept, which allows to reduce the time of searching for the cause to a minimum.


Introduction
Ensuring the effective and safe functioning of the electric power complex of Ukraine largely depends on the stability of the work of its individual components, which are united by a common mode of production, transmission and distribution of electric and thermal energy with common centralized control [1].The existing course "smart grids" position concept's implementation in Ukraine until 2035 is aimed at the active development of Smart Grid systems in the energy system of Ukraine and is fully in line with the priority directions of energy development in the EU.
Thus, one of the important directions of the development of the electric power industry both in the world and in Ukraine is the improvement and construction of electric power networks and IOP Publishing doi:10.1088/1755-1315/1254/1/012036 2 systems according to the Smart Grid concept [2,3].The main idea of Smart grid is the reliable, energy-efficient and high-quality energy supply system.To implement the idea, it is necessary to create a high-performance information and computing infrastructure.
Violation of the operation mode of any of the components of the energy system leads to the emergence of various emergency situations.The most common types of damage are accidents caused by short-circuits and short-circuits to the ground.It is believed that accidents caused by short-circuits make up 70-80% [4].One of the most common places of damage in electrical networks is cable and overhead power lines (power lines).
Therefore, monitoring the parameters of the emergency modes of cable lines and power lines in various sections of electric networks is one of the most important tasks for ensuring the reliability of electricity supply to consumers, which is implemented through the development and implementation of specialized information and measurement systems (IMS) as a component of Smart Grid systems [5,6].The urgency of implementing such systems is due to the fact that the occurrence of emergency situations leads to disruption of the normal power supply of consumers associated with interruptions in power supply, as well as a decrease in the quality of electric energy.In turn, the deterioration of the quality of electrical energy can lead to the failure of equipment of electrical networks and consumers.The effective solution of this problem gives a significant economic effect due to the reduction of interruptions in electricity supply, the reduction of transport costs for bypassing the PL and KL, minimizing the total time of organizing repair and restoration works [2].An effective way for time to cut of searching for a power line damaged section fault indicators with organized as network is to use [6][7][8][9][10].Fault indicators it's devices for monitor the electromagnetic field around the power transmission line and record the fact of damage to the line.
The use of damage indicators is most relevant for distribution networks from 10 kV to 110 kV [6].The main characteristic of these networks is their long length, which is due to a significant number of branches and the presence of areas with difficult access to routes such as overhead and cable lines.During the elimination of emergency situations in distribution electric networks, in particular, during the elimination of accidents associated with the failure of power transmission lines as a result of hostile actions, timely identification of the damaged section of the network acquires primary importance.Detection of a damaged section of the network and in most cases consists in finding the optimal way to bypass all nodes of the topological graph (in the case of overhead power lines bypass all sections of the line [6,7,11,12].In case of damage in the most remote area [13], it is necessary to ensure inspection of the line along its entire length [6].
Therefore, determining the places of occurrence of an emergency situation, the reason that led to its occurrence and the development of measures to eliminate it is a complex and complex problem, the solution of which has become a daily operational task of dispatching services of electrical networks and systems.
The paper aim is to analyse the ways of increasing the reliability of electricity supply to consumers and the effectiveness of restoring electricity supply by operators of distribution systems, by developing a structure of means of identifying emergency conditions in distribution electric networks of IPS of Ukraine [14].

Materials and method
The construction of information and measurement systems (IMS) with primary transducers based on indicators with means of communication and information transmission reduces the time of searching for an accident to a minimum.When damage occurs, all indicators installed in the damaged areas between the data center and the damage site will send response signals to the dispatch center, which allows you to immediately determine the emergency zone and take immediate action.
In this case, the basis of the IMS is the measuring transducers that ensure the determination of emergency mode parameters.In the electrical networks of European countries, damage indicators have been found widely used as measuring transducers (measuring operational parameters in electrical networks) [12,15].The use of damage indicators in the structure of the IMS.So compatible with the means of pre-processing, communication and information transmission, allows to reduce the time to eliminate the cause of the emergency situation to a minimum, which allows immediate identification of the emergency area and the implementation of operational actionist of the research.
Damage indicators, which have found application in electrical distribution networks, are based on different principles of operation.The simplest option of damage indicators are devices that record the exceeding of a certain short-circuit current threshold by the measuring transformer.The distance to the emergency site is determined based on the known calculation parameters of the network, namely the voltage values in the network and the value of the transient resistance at the point of damage.Usually, the indicated indicators for determining the distance to the place of damage on the distribution lines are ineffective due to several branches, which is due to the small values of the short-circuit currents and the length of the electrical networks.This problem is solved by installing damage indicators at the beginning of the branches of each line.In this case, by combining information about the distance to the accident site with information from damage indicators, the exact location of the damaged section of the network is obtained.The disadvantages of such devices are the need for additional calculations and the use of an electromagnetic type measuring transformer.The use of a measuring transformer in many cases is associated with difficulties in their implementation and ensuring operation in the conditions of a continental climate on the territory of Ukraine.Which is characterized by hot summers and frosty winters with significant temperature drops.Information and measurement systems with optical indicators of damage do not have this drawback [16].The principle of operation of optical indicators is based on the use of electro-and magneto-optical effects.The use of the stability of the manifestation of the physical effect of the influence of magnetic or electric fields, which arise under the action of the measured current or voltage on the parameter of optical radiation, allows to ensure high accuracy of measuring currents and voltages.The conversion of the measured electrical values into the parameter of optical radiation takes place directly in the high voltage zone, then, using optical communication channels, the measurement information from the high voltage zone is transmitted to the low-voltage part of the IMS located in the safe zone.A directly measurable value when using electro-and magneto-optical effects is the parameter of optical radiation, the measurement of which can be carried out with high accuracy [17].The obtained results do not depend on external meteorological factors.The main advantage of optical damage indicators is a wide signal bandwidth, high resistance to interference, durability, stability and simplicity of the optical element, as well as the ability to determine very short values of short-circuit currents in the millisecond range [7].Such values of short-circuit currents occur in cases of short-circuit to the ground, for example, during the occurrence of a short-circuit of a phase to the ground or to a neutral wire under the influence of natural elements.A significant disadvantage of optical damage indicators is the high cost of optical damage indicators, which is due to a number of reasons [18]: • the high cost of the manufacturing technology of optical elements and means of measuring their output values; • insignificant power of the output circuits, which is insufficient to activate the existing sets of electromechanical protections, and the need to use additional hardware to increase it; • lack of protection terminals and metering devices produced by domestic and many foreign manufacturers, corresponding inputs for connecting optical converters; • lack of national standards that regulate the verification and determination of the accuracy class of optical sensors and transducers in general; • lack of sufficient statistical data on the use of these devices, which makes it much more difficult to determine their reliability; • the high cost of projects due to the high cost of converting devices and network equipment, as well as the organization of current and voltage circuits in digital form.
Since a significant number of advantages of optical damage indicators can be provided by traditional measuring current transformers, the most effective is the construction and use of fault indicators employ measurement of the magnetic field induced by the current in the current measuring transformer network.The working principle of fault indicators is based on: signal from the secondary winding of the measuring current transformer is proportional to the primary induced current and shifted relative to it by a phase angle close to zero.
Existing damage indicators based on the measuring current transformer, due to the peculiarities of their designs and ensuring the possibility of monitoring them during operation and minimizing measurement errors, are mostly installed only in large nodes of generation and distribution of electrical energy, such as stations and substations.Moreover, the measuring transformer is usually a component of closed and open distribution devices.In addition to the mentioned restrictions on the place of placement, their disadvantage is a long time of installation, adjustment and the need to remove voltage during their installation and maintenance.

Results
To ensure the creation of a damage indicator, which allows you to reduce the time of searching for the cause and the place of occurrence of an emergency situation to a minimum, as well as to ensure connection to operating overhead and cable lines without removing voltage by connecting the output of the secondary winding of the measuring current transformer of the detachable design to the measuring transformers -creators placed directly near the measuring current transformer with the help of a mechanical spring mount.The connection diagram of the current transformer is shown in figure 1, which shows: the load current sensor (LCS) and the measuring system (MS).The IMS contains: a non-invasive current sensor, which consists of an inductive current transformer with a collapsible core (1), a resistor designed to convert the current value into a voltage (2), a shift reference voltage stabilizer implemented on analog elements (3).The system contains: an ATmega328 microcontroller (4), an interface converter chip (5), a 2x16 character liquid crystal display (6) to ensure the display of information in case of need, an LED (9) intended for global indication of a normal and emergency situation on the power line.LCS and VS, together with a personal computer (7) or other specialized means of information processing, on which specialized software is installed, form the IMS of control and monitoring of emergency parameter s of power transmission lines in distributed electric networks.The personal computer (7) is located in the control center in the case of remote access to the IMS or in the immediate vicinity of the IMS in a safe area.
The data collected from the measuring transducers of the LCN indicators are transmitted to the network part of the IMS.Using the obtained data with the help of unit 7, it is possible to monitor the magnitude of the electric current, to recognize the reason for the sudden increase in current strength: the connection of a new load or the appearance of a short-circuit current, and when conducting additional coefficients, to determine the approximate amount of consumed (released) electricity in the sector -divided network and easy to adjust taking into account possible peak loads in branched.Each indicator is equipped with LED 9 to provide a visual indication of the state of the lines, in the case of normal operation of the line, the LED continuously lights up in green color, in the event of an emergency, the LED switches to the red code glow mode.The type of code glow is determined by the type of emergency on the line.In order to verify the results of the research on the components of the system of the intellectualized emergency meter for the identification of damage to overhead and cable lines, test and demonstration stand was created, the photo of which is shown in figure 2. The test was carried out by the method of direct comparison with an exemplary meter of the information component.The ProsKit MT-1270 device with an accuracy class of 0.5 for determining the current value and an ammeter E59 with an accuracy class of 0.5 were used as sample meters.The obtained measurement results are shown in figure 3.
The obtained results (figure 3) confirm the functionality of the intellectualized emergency condition meter for distribution electrical networks in a single-phase cable network with a collapsible core.The development and implementation of such indicators is the basis for the construction of specialized information and measurement systems in electrical networks, the use of which reduces transport costs during the search for places of damage, minimizes the total time of organizing restoration and repair works, which in turn allows to increase electricity supply reliability to consumers and receive a positive economic effect by reducing of interruptions in their energy supply.