scholarly journals Distance backup protection using supply currents on a line with several branches

Vestnik IGEU ◽  
2019 ◽  
pp. 49-59
Author(s):  
L.M. Kolesov ◽  
V.V. Mozhzhukhina
Keyword(s):  
Transmission Lines ◽  
Short Circuit ◽  
Impedance Measurement ◽  
Total Power ◽  
Distance Protection ◽  
Backup Protection ◽  
Response Characteristics ◽  
Mode Recognition ◽  
Urgent Task ◽  
Short Circuits

The third step of distance protection is used as backup protection against phase-to-phase short circuits on 110–220 kV transmission lines. The main problem when using these protections on a line with several branches is to ensure the effectiveness of distant backup protection in case of phase-to-phase short circuits behind branch transformers of substations. The effective solution to distant backup protection is possible to provide by expanding the information base of protection. Currently, backup protection of lines with branches is being developed with control of currents and their components when using a communication channel, and based on algorithmic models of the facility. In this regard, the urgent task is to develop an algorithm for the distance protection ensuring the required sensibility during short circuits on the lower voltage side of the branch transformers. Analytical methods of determining the impedance measurement and simulation in Simulink and SimPowerSystems of the Matlab modeling system are used. The effectiveness of distant backup protection can be evaluated on the basis of recognition possibility of short circuit modes behind the branch transformers. Analytical expressions have been obtained to determine the impedance measurement during phase-to-phase short-circuits behind a branch transformer and under load conditions. Criteria have been developed to assess the proposed protection possibility to recognize the mode of phase-to-phase short circuits behind the branch transformer. Studies have shown that the main factor determining the possibility of mode recognition is the ratio between the protected transformer power and the total power of the branches loads. The use of several impedance measuring elements with their own response characteristics for branches with transformers of different capacities provides mode recognition for any possible correlation of power of branch substations. The use of the distance protection implementation option developed by the authors allows providing the required sensitivity for short circuits behind branch transformers and to solve the problem of distance backup line protection on a line with several branches. The reliability of the data obtained is confirmed by the correspondence of analytical research and simulation results.

scholarly journals Designing of a distance protection stage based on data on branched line supply end currents

Vestnik IGEU ◽  
2019 ◽  
pp. 44-53 ◽  
Author(s):  
L.M. Kolesov ◽  
V.V. Mozhzhukhina
Keyword(s):  
Low Power ◽  
Transmission Lines ◽  
Low Voltage ◽  
Impedance Measurement ◽  
Distance Protection ◽  
Long Distance ◽  
Backup Protection ◽  
Response Characteristics ◽  
Short Circuits ◽  
Analytical Expressions

At present, in 110–220 kV transmission lines the problem of interphase short-circuits in the long-distance backup protection zone, in most cases, is solved by a backup level of current or distance protection. The existing protection solutions for lines with branching are based on the use of special high-voltage equipment, various current components and their ratios, a virtual resistance relay; on the control of emergency and orthogonal current components with adaptive braking and signal correction as well as with correction of the response characteristics according to the data on the voltage change and the state of the switching devices of the main substation. A number of developments are aimed at increasing the sensitivity of back-up protection of branch substations by changing the connection circuit, improving the response characteristics and refining the method for selecting the settings. However, these protection solutions in many cases do not provide the required sensitivity during short circuits on the low voltage side of a low-power branch transformer. All this means that an urgent problem to be solved is developing an algorithm for the operation of backup protection, providing the required sensitivity to short circuits on the low voltage side of the branch transformer. Analytical methods and simulation in the Simulink and SimPowerSystems packages of the Matlab modeling system were used to determine the impedance measurement of the distance protection measuring element. A mathematical model of the lumped-parameter line was used. When deriving analytical expressions, the impedances of the positive and negative sequences were assumed to be equal. Analytical expressions were obtained for determining the impedance measurement of the proposed and existing distance protection during phase-to-phase short-circuits appearing after a branch transformer and under load conditions. The studies have shown that the proposed distance protection has the required sensitivity to short circuits on the low voltage side of the branch transformer and the necessary detuning from load modes. The characteristics and methods for selecting response parameters of the additional stage of distance protection were determined using information on the currents of the line supply ends. The use of an additional distance protection stage developed by the authors based on the sum of currents of the line supply ends can ensure the required sensitivity to phase-to-phase short circuits on the low voltage side of the branch transformer with a star-delta connection circuit and solve the problem of distant backup protection of low power branch substations. The reliability of the data obtained is confirmed by the correspondence of the results of the analytical research and simulation modeling.

Study on a New Setting Method of Distance Relay with Superconducting Fault Current Limiter Adapt in the Grid

2012 ◽  
Vol 588-589 ◽  
pp. 471-474
Author(s):  
Jun Mei ◽  
Bin Liu ◽  
Jian Yong Zheng ◽  
Lei Yao
Keyword(s):  
Transmission Lines ◽  
Single Phase ◽  
Short Circuit ◽  
Impedance Measurement ◽  
Simulation Software ◽  
Fault Current ◽  
Fault Current Limiter ◽  
Distance Protection ◽  
Superconducting Fault Current Limiter ◽  
Current Limiter

Considerable attention is given towards developing Superconducting fault current limiter (SFCL) due to increasing short circuit levels in transmission lines, which itself imposes further changes on the measured impendence at the relaying point and causes significant impact on the lines’ relay protection, especially on the distance protection as the single-phase grounding fault occurs. In this paper, resistive superconducting fault current limiter connected to the grid is studied as the model to analysis how SFCL affects the grounded short-circuit impedance relay’s setting, then an new setting method of distance protection for the SFCL-equipped line is proposed. Finally, a power system model is built to analysis the theory by PSCAD / EMTDC simulation software. The results show that in the condition of using the impedance relays’ new setting method, impedance measurement error is greatly reduced, SFCL and line distance protection can work in coordination with each other properly.

Short circuits currents comparison of 6 (10) kV and 20 kV.

2020 ◽  
Vol 14 (1) ◽  
pp. 21-26
Author(s):  
S. SKRYPNYK ◽  
◽  
A. SHEINA ◽  
Keyword(s):  
Power System ◽  
Transmission Line ◽  
Transmission Lines ◽  
Power Supply ◽  
Short Circuit ◽  
Electric Arc ◽  
Electrical System ◽  
Three Phase ◽  
Short Circuits ◽  
Short Circuit Currents

Most failures in electrical installations are caused by short circuits (short circuits), which occur as a result of a failure in the electrical strength of the insulation of the conductive parts. A short circuit is an electrical connection of two points of an electric circuit with different values of potential, which is not provided by the design of the device, which interferes with its normal operation. Short circuits may result from a failure of the insulation of the current-carrying elements or the mechanical contact of the non- insulated elements. Also called a short circuit is a condition where the load resistance is less than the internal resistance of the power source. The reasons for such violations are various: aging of insulation, breakages of wires of overhead transmission lines, mechanical damages of isolation of cable lines at ground works, lightning strikes in the transmission line and others. Most often, short-circuits occur through transient resistance, such as through the resistance of an electric arc that occurs at the point of damage to the insulation. Sometimes there are metallic short circuits in which the resistance of the electric arc is very small. The study of short circuits in the power grid is a major step in the design of modern electrical networks. The research is conducted using computer software, first by modeling the system and then simulating errors. A malfunction usually leads to an increase in the current flowing in the lines, and failure to provide reliable protection can result in damage to the power unit. Thus, short-circuit calculations are the primary consideration when designing, upgrading, or expanding a power system. The three-phase short circuit is the least likely. However, in many cases, the three-phase short circuit is associated with the most severe consequences, as it causes the highest power imbalances on the shafts of the generators. The study of transients begins with the mode of three-phase closure due to its relative simplicity in comparison with other types of asymmetry. In most cases, the analysis and calculation of the transient regime of the electrical system involves the preparation of a calculated scheme of substitution, in which the parameters of its elements are determined in named or relative units. The electrical substitution circuitry is used to further study the transients in the power system. The definition of electrical and electromagnetic quantities in relative units is widely used in the theory of electric machines. This is because it significantly simplifies the theoretical calculations and gives the results a generalized view in the practical calculations of currents and residual voltages at the short circuit. By the relative value of any value is understood as its relation to another value of the same name, taken as the base. So, before presenting any quantities in relative units, we need to choose the basic units. In the electrical system with increased voltages, the overall load capacity of the network increases, which in turn makes it possible to supply high-quality electrical energy over a greater distance. In the process of comparing the type of transmission lines, it should be noted that the advantages of the cable transmission line. According to the results of the calculation of short-circuit currents, it can be concluded that in networks with a larger line cross-section and a higher voltage, the short-circuit currents are larger. Thus, during the transition of the electric networks to the higher voltage class of 20 kV, the currents of the KZ increased by 43% compared to the 6 kV electric network. This analysis shows that the importance of reliable power supply in the power supply system for high voltage classes must be high and have equipment to prevent emergencies. In the future, it is planned to develop a systematic calculation of short-circuit currents for a number of transmission lines and to conduct mathematical modeling in the system of applications for the study of transient processes at short circuits.

scholarly journals A Novel Two-step Distance Protection for Flexible HVDC Transmission Lines

2021 ◽  
Vol 256 ◽  
pp. 02017
Author(s):  
Zeya Fang ◽  
Minghao Wen ◽  
Junchao Zheng ◽  
Minghao Wen
Keyword(s):  
Transmission Lines ◽  
Low Frequency ◽  
Lumped Parameter Model ◽  
Distance Protection ◽  
Backup Protection ◽  
Hvdc Transmission ◽  
Protection Method ◽  
Dc Line ◽  
Hvdc Line ◽  
Step Distance

DC line fault is one of the key problems that must be solved in a flexible HVDC system. During quite a long time between the existing main protection and backup protection of the HVDC line, there is no line protection method to detect the fault, which may lead the protection at the AC side to act before the backup protection of the DC line. To solve the problem, a novel two-step distance protection for flexible HVDC lines is proposed in this manuscript. Firstly, based on the uniform distributed parameter model, the equivalent lumped parameter model of the HVDC transmission line at low frequency is analyzed. Secondly, according to the time domain differential equation and the least squares algorithm, novel distance protection based on the iterative calculation of fault distance is proposed, which can eliminate the influence of distributed capacitive current and improve the precision of calculation. To improve the rapidity and reliability of the distance protection, low pass filters with two different cut-off frequencies are used to process the electrical quantities. Finally, simulation results show that the proposed distance protection can respond to metallic poleto-ground faults and pole-to-pole faults rapidly and reliably.

scholarly journals Short circuit fire risk assessment in investigating and examining fires caused by emergency modes in overhead transmission lines

2022 ◽  
Vol 6 (4) ◽  
pp. 363-368
Author(s):  
Yu. S. Kozlova
Keyword(s):  
Transmission Lines ◽  
Fire Hazard ◽  
Short Circuit ◽  
Electric Power System ◽  
Ignition Source ◽  
Electrical Network ◽  
Fuel Load ◽  
Overhead Transmission Lines ◽  
Protection Devices ◽  
Short Circuits

Emergency modes (short circuits) in electric power system and equipment are the main technical cause of fires. However, it is not always possible to prove the involvement of a particular operating mode in a fire. The fire hazard can be due to three components: a fuel load, an oxidizer and an ignition source. Since overhead transmission lines are used in an open space, they are oxidized. The presence of a fuel load is confirmed by a fire. The source of ignition should be identified. The aim of the study is to develop an algorithm for assessing the fire hazard for short circuits in overhead transmission lines with 1000 V. The study was conducted using scientific analysis, physical experiment and simulation. The ignition source is due to the appearance of an energy source with parameters sufficient to ignite a fuel load. The probability of ignition in overhead line wires depends on the probability of occurrence of the short circuit itself  ( Qi (v1) ) , the probability of failure of protection devices  ( Qi (v2) ), and the probability that the electric current value in the event of a fault is in the range of fire hazard values (Qi(z)). The values of the first two components are determined on the basis of statistical data, taking into account the theory of reliability. The third component is based on the experiment results. The experimental studies made it possible to establish the ranges of fire hazard values for uninsulated aluminum wires of various cross-sections, thereby providing the possibility of calculating ( Qi (z). Using the data obtained and information about the nature of changes in short-circuit currents and performance characteristics of protection devices, depending on the line length, an algorithm for assessing the fire hazard for a short circuit was developed. The results make it possible to assess the fire hazard for short circuits in various sections of the electrical network, made by overhead transmission lines, and to establish the involvement of sparks generated by short circuits in a fire

scholarly journals Fault Location in High Voltage Transmission Lines Using Resistance, Reactance and Impedance

2018 ◽  
Vol 2 (2) ◽  
pp. 78
Author(s):  
Samira Seghir ◽  
Tahar Bouthiba ◽  
Samia Dadda ◽  
Rebiha Boukhari ◽  
Abdelhakim Bouricha
Keyword(s):  
Transmission Lines ◽  
Fault Location ◽  
Short Circuit ◽  
Short Circuit Current ◽  
Practical Case ◽  
Distance Protection ◽  
Creative Commons ◽  
On Line ◽  
Open Access Article

This paper presents two methods for on-line computation of dynamic fault location in HV transmission lines using three means; resistance, reactance and impedance. These methods can be used for dynamic distance protection of the transmission line. The Gilchrist method and McInnes method are presented. The proposed methods use digital set of short circuit current and voltage measurements for estimating fault location. A practical case study is presented in this work to evaluate the proposed methods. A study is done to evaluate the best mean to locate the fault. A comparison of these two methods is presented. MATLAB-Simulink software was used to do all the tests. Results are reported and conclusions are drawn.  This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Backup Protection for Six-Phase Transformer Based on Six-Sequence Components

2013 ◽  
Vol 385-386 ◽  
pp. 1127-1130 ◽  
Author(s):  
Hai Jiang Wang ◽  
Yan Xia Zhang ◽  
Zhong Yuan Deng
Keyword(s):  
Theoretical Analysis ◽  
Transmission Lines ◽  
Power Transmission ◽  
Short Circuit ◽  
Simulation Experiments ◽  
Backup Protection ◽  
System A ◽  
Sequence Components ◽  
Zero Sequence ◽  
Phase Transmission

The six-phase transmission can improve the power transmission density of the transmission lines effectively, and save line corridor. To save the problem that the sensitivity of the traditional transformer backup protection is low in six-phase transmission system, a backup protection for six-phase transformer was proposed. An over-current protection criterion is proposed for interphase short circuit and opposite zero sequence over-current protection criterion is proposed for ground faults, based on the six-sequence components relationship, and the existence of six-sequence components in different fault types. Theoretical analysis and EMTDC simulation experiments prove that the scheme is feasible.

scholarly journals Development of the method of determining the location of a short circuit in transmission lines

2021 ◽  
Vol 2061 (1) ◽  
pp. 012033
Author(s):  
K Suslov ◽  
N Solonina ◽  
Z Solonina ◽  
A Akhmetshin
Keyword(s):  
Transmission Lines ◽  
Fault Location ◽  
Short Circuit ◽  
Search Time ◽  
Distribution Networks ◽  
Power Lines ◽  
Supply And Distribution ◽  
Short Circuits ◽  
Reliable Power Supply ◽  
Short Time

Abstract One of the serious problems of the reliable functioning of energy systems is the disruption of the performance of overhead and cable transmission power lines caused by various reasons. Most of the power outages occur in distribution networks. Particularly dangerous short-circuits in the supply and distribution network, due to unpredictable natural disasters. To ensure uninterrupted and reliable power supply to consumers, it is necessary to identify and eliminate the malfunction in a short time to reduce damage. Finding and troubleshooting a line is an important task. The authors proposed a method for quickly determining the location of a short circuit in power lines. The proposed method allows to reduce search time and increase the accuracy of determining the fault location.

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