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RU-2861652-C1 - METHOD FOR DETERMINING FAULT LOCATION ON OVERHEAD POWER LINE EQUIPPED WITH LIGHTNING PROTECTION CABLE

RU2861652C1RU 2861652 C1RU2861652 C1RU 2861652C1RU-2861652-C1

Abstract

FIELD: electric power engineering. SUBSTANCE: invention can be used to determine the fault location on overhead power lines equipped with a lightning protection cable along the entire length. The essence of the claimed method lies in the fact that information on the zero-sequence resistances of the overhead power line , source and load is additionally used in the calculations , the zero-sequence current from the source side is measured, a quadratic equation is additionally used where the distance to the fault location of the overhead power line is calculated using the expression , where and only such a value is selected which meets the condition , and the distance to the damage site is determined by the expression , where is the length of the overhead power line. EFFECT: increased accuracy of determining the distance to the fault location on overhead power lines equipped with a lightning protection cable, by eliminating errors associated with the presence of a reactive component of the fault resistance. 1 cl, 2 dwg

Inventors

  • KULIKOV ALEKSANDR LEONIDOVICH
  • Fedosov Denis Sergeevich
  • Kriukov Evgenii Valerevich
  • Cherneev Pavel Pavlovich

Dates

Publication Date
20260506
Application Date
20251022

Claims (10)

  1. A method for determining the location of damage on an overhead power line equipped with a ground wire, including:
  2. a) obtaining known circuit parameters, including the positive sequence resistance of the power transmission line Z L1 , as well as measuring the current before and after the fault and the voltage values at a monitored location on the specified power transmission line;
  3. b) calculation of the load and source resistance Z load and Z S using the known circuit parameters and the values of current and voltage before (l ps, V ps ,) and after (l sf, V sf ) the fault measured in step a),
  4. c) determination of equations that take into account the influence of the fault resistance Z f and the fault-induced change in load current and that relate the fault location with known circuit parameters,
  5. Where
  6. characterized in that the influence of the reactive component of the fault resistance on the accuracy of determining the fault location of an overhead power line equipped with a ground wire is minimized; along with the parameters of the overhead power line, information on the zero-sequence resistance of the overhead power line Z L0 , the source Z S0 and the load Z load 0 is additionally stored in the information storage unit of the device implementing the method and used in subsequent calculations; the zero-sequence current l 0 is measured from the source side; in addition, when determining the distance to the fault location of the overhead power line, a quadratic equation is used
  7. Where
  8. in the block for calculating the distance to the location of damage of the device implementing the method, the distance to the location of damage of the overhead power line is calculated based on the joint solution of equations (2) and (3), as well as using the expressions:
  9. and only this value is selected , which meets the condition , and the distance to the place of damage is determined by the expression
  10. Where – the length of an overhead power line equipped with a ground wire.

Description

The proposed invention relates to the electric power industry and can be used to determine the fault location (FL) on overhead power lines (OPL) equipped with a ground wire (GT) along the entire length. A method for detecting short circuits (SC) to ground in overhead power transmission lines equipped with a zero-sequence transformer (ZS) is known [Author's Certificate No. 533886, IPC G01R 31/08, published 10/30/76, Bulletin No. 40]. According to the method, the zero-sequence current (NS) and voltage magnitudes are measured and stored at one end of the line, the NS current magnitude in the ZS of the damaged line is additionally measured and stored at the same end, and the distance to the location of the ground fault is determined by the formula: Where – respectively, the current and voltage modules of the NP, measured at the substation (PS), from where the calculation is carried out ; – the NP current module, measured in GT at the same substation; – resistance of the power transmission line; – resistance of the NP GT; – mutual induction resistance between the overhead power line and the gas turbine; – length of the power transmission line (PTL) (ground wire). The disadvantages of the method are the need to measure the NP current modulus in the GT, as well as low accuracy associated with some of the assumptions made when obtaining the calculation formula (1). A known method for identifying a damaged section of a transmission line with a GT [Author's Certificate No. 744381, IPC G01R 31/08, published 30.06.80, Bulletin No. 24] is based on measuring the fault current in the support components and comparing the measured fault current with the permissible value of this current. The magnitude and direction of fault currents are measured on sections of the transmission line on each side of the support, the directions of fault currents on sections of the transmission line on each side of the support are compared with the direction of the fault current in the support components, and sections of the transmission line with fault currents that match the direction of the fault current in the support components are identified. The damaged section is determined by the identified section of the transmission line, and damaged supports are identified by the presence of two identified sections of the transmission line. The disadvantage of this method is the complexity of implementation, associated with the need to carry out measurements on different supports and sections of the power transmission line, as well as the large time costs involved in performing such measurements. A method for fault detection on a transmission line equipped with a GT is known [RU Patent No. 2834732, IPC G01R 31/08, published 13.02.2025 Bulletin No. 5], according to which the damaged phase of the transmission line is determined, the phase voltages and currents of the emergency and pre-emergency modes at the beginning of the transmission line are measured, the symmetrical components of the currents are determined from the measured phase currents, the purely emergency positive sequence (PS) current is determined as the difference between the PS currents of the emergency and pre-emergency modes, and a reference current is used in the expression for calculating the distance to the fault location, which is selected as the PS current, the negative sequence current, or the purely emergency PS current. According to the method, the influence of the reactive component of the fault resistance on the accuracy of the fault detection of the overhead power line equipped with a gas transformer is minimized; along with the parameters of the overhead power line, information on the resistance parameters of the systems connected to the overhead power line is additionally stored in the memory of the device implementing the method and used in subsequent calculations; to minimize the influence of the reactive component of the fault resistance on the accuracy of the fault detection of the overhead power line, the distance is calculated to the place of damage according to the quadratic equation: , – complex voltages and current of the damaged phase; – reference current; – NP current; – complex specific resistance of the power transmission line; ; – length of overhead power lines; – complex coefficient of compensation of the NP current, ; – complex specific resistance of the power transmission line; And – complex resistances of systems connected to the ends of the overhead power line; solve a quadratic equation, and its roots: The device is checked in the comparison unit for possible location within the overhead power line; the value of the root of the quadratic equation lying within the overhead power line is taken as the distance value to the place of damage and from the output of the comparison block it is transmitted to the output of the device implementing the method. The disadvantages of the method are the complexity of technical implementation associated with the large