Protection from Single-Phase Short Circuits to Ground Based on Monitoring the Zero Sequence Capacitance in 6 – 10 kV Cable Networks

2021 ◽  
Author(s):  
V. A. Shuin ◽  
O. A. Dobryagina ◽  
T. Yu. Shadrikova ◽  
Yu. D. Kutumov
Keyword(s):  
Single Phase ◽  
Cable Networks ◽  
Zero Sequence ◽  
Short Circuits

scholarly journals The influence of changing resistance on the determination accuracy of short circuits in power lines

2021 ◽  
Vol 288 ◽  
pp. 01091
Author(s):  
Serdar Nazarov ◽  
Gurbangulych Kelov ◽  
Berdimyrat Gochyev
Keyword(s):  
Single Phase ◽  
Short Circuit ◽  
Stable State ◽  
Short Circuit Current ◽  
Scientific Work ◽  
Electric Power System ◽  
Electrical Networks ◽  
Zero Sequence ◽  
Short Circuits ◽  
Maintenance Personnel

In high-voltage electrical networks, the occurrence of short circuits leads to forced interruptions in the power supply of large consumers and disruptions in intersystem communications. More than 65% of all types of occurring short circuits are single-phase short circuits [1]. In a single-phase short circuits (SPSC), a change in the zero sequence resistance (ZSR) especially significantly affects the inaccuracy in detection of damage sites (DDS). When choosing DDS methods, preference is given to remote methods according to the parameters of the emergency conditions (PEC), which are recorded by special instruments or determined from the oscillograms of emergency conditions. The use of modern microprocessor-based relay protection and automation devices (RPA) [26] or emergency event recorders allow viewing the oscillograms of emergency events. In a branched 110 kV network with a complex configuration, the DDS accuracy is influenced by a change in the ZSR. Averaging of specific parameters often leads to erroneous results. The choice of one value from the oscillograms puts the maintenance personnel in difficulty. In the scientific work, the influence of changes in the ZSR on the accuracy of the DDS is considered. The changes in the ZSR are influenced by the position of the on-load voltage regulator (OLTC) switches of transformers with a grounded neutral. In the work, for a more accurate record of the specific parameters of the network, a calculation program has been compiled, which allows making changes in the calculated specific parameters of the network. To determine the short-circuit current from the oscillograms, it is proposed to determine the stable state of accidents in which the current value will be approximately the same. The analysis of the oscillograms of SPSC in 110-220 kV networks in the southern part of the electric power system of Turkmenistan has been carried out.

scholarly journals Complex of technical solutions for protection and selective signaling of single-phase earth faults in 6-10 kV distribution cable networks

2020 ◽  
Vol 216 ◽  
pp. 01017
Author(s):  
Vladimir Shuin ◽  
Tatiana Shadrikova ◽  
Olga Dobryagina ◽  
Elena Shagurina
Keyword(s):  
Power Supply ◽  
Single Phase ◽  
Economic Damage ◽  
New Approach ◽  
Root Cause ◽  
Cable Networks ◽  
Predominant Type ◽  
Zero Sequence ◽  
Technical Solutions ◽  
Supply Systems

Single-phase earth faults are the predominant type of damage in distribution 6-10 kV cable networks, and are often the root cause of power failures to consumers, accompanied by significant economic damage. Therefore, reliability for about 50% of consumers of industrial and urban power supply systems depends on the technical perfection of protection against earth faults. The currently used approach to the design of protection and signaling of earth faults, based on the application of the existing concept of selectivity of considered protection, does not always ensure the achievement of the main goal – increasing the reliability of power supply to consumers. To improve the reliability of power supply, new technical solutions are needed that provide not only selective detection of the damaged connection for all types of single-phase earth faults, but also the recognition of the most dangerous for the network and the protected connection faults types for automatic selection the most effective protection action (signal or shutdown). Within the framework of the existing approach, the design of protection against earth faults with the specified properties is possible only on the basis different methods of its implementation in networks with different neutral grounding modes, which is associated with the complication of protection circuit, its design and exploitation. A new approach has been proposed that provides universal technical solutions for protection and signaling of earth faults for 6–10 kV cable networks with various neutral grounding modes. To implement the proposed approach, universal adaptive current protection and universal admittance protection based on the control of the capacitance of zero sequence loop of the protected connection have been developed.

scholarly journals Method of adaptive current protection against earth faults in 6–10 kV cable networks with an insulated neutral

Vestnik IGEU ◽  
2019 ◽  
pp. 31-39 ◽  
Author(s):  
O.A. Dobryagina ◽  
V.V. Tyutikov ◽  
T.Yu. Shadrikova ◽  
V.A. Shuin
Keyword(s):  
Dynamic Stability ◽  
Single Phase ◽  
Simulation Models ◽  
Matlab Simulation ◽  
Transient Conditions ◽  
Cable Networks ◽  
Overcurrent Protection ◽  
Zero Sequence ◽  
High Dynamic ◽  
Response Current

Simple and reliable zero sequence overcurrent protection in distribution 6–10 kV cable networks with an insulated neutral is most widely used for protection against single phase earth faults. However, protection of this type in many cases does not provide the required sensitivity to internal (inside the protected zone) faults as it must be tuned to the response current from surge transients during external faults through an intermittent arc. It is possible to increase the sensitivity if adaptive current protection is applied. However, the known methods for its implementation are only effective for stable faults through transient resistance but do not provide high dynamic stability of operation in transient conditions in case of arc intermittent earth faults that are the most dangerous for the network. Therefore, an urgent problem to be solved now is improving the principles of adaptive current protection against earth faults. To compare the efficiency of the known and proposed principles of adaptive current protection implementation taking into account the complexity of transients during earth faults through an intermittent arc in 6–10 kV cable networks, we used Matlab simulation with the SimPowerSystem and Simulink extension packages. The research into the operation algorithms of adaptive current protection against earth faults was carried out on simulation models of 6–10 kV cable networks with an insulated neutral and with neutral grounding through a high-value resistor. The studies on the simulation models have shown that the known methods of implementation of adaptive current protection against earth faults based on the use of full zero sequence currents and voltage are ineffective during intermittent arc earth faults. The authors propose a method of adaptive current protection against earth faults in 6–10 kV cable networks with an insulated neutral and with neutral grounding through a high-value resistor that provides a significant increase in dynamic stability of transient operation with arc ground faults and allows using only zero sequence current and voltage components of the operating frequency of 50 Hz as the actuating quantities. The proposed method of implementing adaptive current protection against earth faults in 6–10 kV cable networks with an insulated neutral and with neutral grounding through a high-value resistor does not only increase the sensitivity of this protection type to earth faults through transient resistence and dynamic stability of operation in transient condiitons in case of arc intermittent earth faults but also broadens the range of its possible applications

scholarly journals A novel fault section locating method based on distance matching degree in distribution network

2021 ◽  
Vol 6 (1) ◽  
Author(s):  
Zhenxing Li ◽  
Jialing Wan ◽  
Pengfei Wang ◽  
Hanli Weng ◽  
Zhenhua Li
Keyword(s):  
Single Phase ◽  
Distribution Network ◽  
Matlab Simulink ◽  
Grounding Resistance ◽  
Blind Zone ◽  
System Transition ◽  
Transition Resistance ◽  
Zero Sequence ◽  
Matching Degree ◽  
Amplitude Characteristics

AbstractFault section location of a single-phase grounding fault is affected by the neutral grounding mode of the system, transition resistance, and the blind zone. A fault section locating method based on an amplitude feature and an intelligent distance algorithm is proposed to eliminate the influence of the above factors. By analyzing and comparing the amplitude characteristics of the zero-sequence current transient components at both ends of the healthy section and the faulty section, a distance algorithm with strong abnormal data immune capability is introduced in this paper. The matching degree of the amplitude characteristics at both ends of the feeder section are used as the criterion and by comparing with the set threshold, the faulty section is effectively determined. Finally, simulations using Matlab/Simulink and PSCAD/EMTDC show that the proposed section locating method can locate the faulty section accurately, and is not affected by grounding mode, grounding resistance, or the blind zone.

The Field Test of High Voltage Cable Impedance Parameters

2014 ◽  
Vol 986-987 ◽  
pp. 1682-1684
Author(s):  
Gang Chen ◽  
Qing Hao Wang ◽  
Guo Bin Liu ◽  
Tian Shu Hai ◽  
Bo Liu ◽  
...  
Keyword(s):  
Field Test ◽  
High Voltage ◽  
Single Phase ◽  
Measuring Method ◽  
Theory Analysis ◽  
Zero Sequence ◽  
Impedance Parameters

The cables in 66 kV and 220 kV systems are used in single-phase style, and it must be grounded between the cables. The connection ways between different lengths of cables are in different ways, thus, it may occur influence to circuit parameters, especially to zero sequence impedance. In order to clarify the situation from theory analysis to calculate impedance under all kinds of connection modes, the paper gives an actual cable measured value, and introduces the correct measuring method, together, points out the matters needing attention in the measurement.

scholarly journals Voltages Induced in Overhead Ground-Wire Cable as Risk Factor. Part 1

2016 ◽  
Vol 5 (1) ◽  
pp. 28-40 ◽  
Author(s):  
Токарский ◽  
A. Tokarskiy ◽  
Рубцова ◽  
Nina Rubtsova ◽  
Рябченко ◽  
...  
Keyword(s):  
Risk Factor ◽  
Single Phase ◽  
Interval Length ◽  
Maximum Permissible Level ◽  
Overhead Transmission Line ◽  
Spark Gap ◽  
Three Phase ◽  
Electric And Magnetic Fields ◽  
Short Circuits ◽  
Selection Of

To ensure the staff safety under hot-line overhead transmission line (OTL) maintenance, as well as overhead ground-wire cable (OGWC) insulation integrity maintaining, by the example of three-phase 750 kV OTL has been presented an algorithm for calculation of voltages and electromotive forces (EMF) induced in this line’s OGWC by electric and magnetic fields (EF and MF) generated by OTL phases’ voltages and currents. Algorithms for calculation of line-to-earth voltages distribution along grounded at one end OGWC’ intervals have been given. It has been shown that the voltage induced at OGWC by EF of 750 kV OTL is much less than the voltage induced by this OTL’s MF. For single-phase short circuits modes has been presented an algorithm for selection of grounded at one end OGWC’ interval length by condition of respecting of voltage’s maximum permissible level on a spark gap shunting OGWC’s insulator set.

The Poynting Vector and the New Theory of a Transformer. Part 11. Three-Phase Three-Core Transformers without a Neutral Wire

2021 ◽  
Vol 1 (1) ◽  
pp. 23-34
Author(s):  
Mansur A. SHAKIROV ◽  
Keyword(s):  
Equivalent Circuit ◽  
Single Phase ◽  
Poynting Vector ◽  
Magnetic Circuit ◽  
Phase Zone ◽  
Field Patterns ◽  
Three Phase ◽  
Short Circuits ◽  
The Difference ◽  
Mathematical Relations

A topological equivalent circuit for a three-phase three-core transformer reflecting the spatial structure of its magnetic system is developed. Owing to this approach, it became possible to represent the magnetic fluxes of the magnetic circuit’s all main sections and the apertures for each of three phases directly in the circuit in the absence of the windings’ neutral wires. The circuit is constructed by stitching together the anatomical circuit models of single-phase transformers obtained in the previous parts with taking into account the relationships between the fluxes at the junctions of the phase zones in iron. Its validity is confirmed by the rigor nature of the physical and mathematical relations for idealized transformers with infinite magnetic permeability of iron and simplified magnetic field patterns, which corresponds to the generally accepted approach with neglecting the magnetization currents. The difference lies in the fact that the developed model takes into account the heterogeneity of magnetization in different parts of the magnetic circuit with allocating more than 30 sections in the iron and apertures. The transition to the model of a real three-core transformer is carried out by adding four nonlinear transverse magnetization branches in each extreme phase zone and eight branches in the central phase zone to the idealized equivalent circuit. It is shown that in cases of winding connections without neutral wires, there is no flux of the Poynting vector in interphase zones in any unbalanced mode. In this case, the problems connected with the occurrence of fluxes exceeding the no-load fluxes under the conditions of symmetric and asymmetric short circuits, as well as the occurrence of buckling fluxes in these modes in the region outside the transformer iron, are solved.

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