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Resonant grounding system high resistance grounding fault transition resistance identification method

A high-impedance ground fault and transition resistance technology, which is applied in the direction of measuring resistance/reactance/impedance, measuring electricity, measuring electrical variables, etc., can solve problems such as failure to identify transition resistance at fault points, and achieve a wide range of practical application value, convenient implementation, The effect of improving motion performance

Active Publication Date: 2017-09-22
CHINA UNIV OF PETROLEUM (EAST CHINA)
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The main difficulty faced by this method is that the line selection device needs to be connected to three-phase current signals and is greatly affected by TV / TA transmission errors (such as unbalance)
[0006] For the resonant grounding system, the power frequency current itself has no obvious fault characteristics when the high resistance is grounded, and the power frequency zero-sequence current and power frequency zero-sequence voltage of the fault line and the healthy line are capacitively constrained, and the transition resistance of the fault point cannot be identified

Method used

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  • Resonant grounding system high resistance grounding fault transition resistance identification method
  • Resonant grounding system high resistance grounding fault transition resistance identification method
  • Resonant grounding system high resistance grounding fault transition resistance identification method

Examples

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Effect test

Embodiment 1

[0039] A method for identifying transition resistance of a high-impedance ground fault in a resonant ground system, comprising the following steps:

[0040] Step 1: Collect the zero-sequence voltage of the busbar online. When the zero-sequence voltage amplitude of the busbar is at U th1 0f th2 when (normal U th1 =15V, U th2 =90V), it means that a high-resistance grounding fault occurs in the system, and the line selection device for a small-current grounding fault starts according to the zero-sequence voltage of the busbar. Based on the fault data such as zero-sequence current signal, fault duration, and fault occurrence time at the exit of each feeder, the fault line is selected according to the recorded data;

[0041] Step 2: Extract the zero-sequence current at the outlet of the faulty feeder, the zero-sequence current at the outlet of any healthy feeder, and the transient components of the zero-sequence voltage of the bus, respectively i 0n_T i 0i_T (i=1,2,...,n-1), u ...

Embodiment 2

[0051] It can also be approximately considered that the projected component of the transient zero-sequence current of the fault line on the transient zero-sequence voltage is the transient zero-sequence current of the fault point, so that the transition resistance value of the fault point can be calculated.

[0052] Then, the identification method of transition resistance for high-impedance ground fault in resonant grounding system includes the following steps:

[0053] Step 1: Extract the transient components of the zero-sequence current at the outlet of the faulted feeder and the zero-sequence voltage of the busbar, i 0n_T , u 0f_T ;

[0054] Step 2: The projection coefficient of the transient zero-sequence current at the outlet of the faulted feeder to the transient zero-sequence voltage of the bus is ξ n ;

[0055]

[0056] Step 3: Calculate the transient current at the fault point by using the transient zero-sequence voltage of the busbar and the transient zero-sequ...

Embodiment 3

[0061] set up image 3 A 1500Ω high-resistance grounding fault occurs at the position of K2 of the middle line, and the method in Example 1 is used to identify the transition resistance of the fault point:

[0062] Step 1: When a high-impedance ground fault occurs in the line, the line selection device starts according to the zero-sequence voltage of the busbar. When the zero-sequence voltage value of the busbar reaches the device startup threshold, the device is started to select the faulty line, and the startup device records the zero-sequence voltage of the busbar. , The zero-sequence current signal at the outlet of each feeder, such as Figure 4 shown;

[0063] Step 2: Extract the zero-sequence current at the outlet of the faulty feeder, the zero-sequence current at the outlet of healthy feeder 1, and the transient component i of the zero-sequence voltage of the busbar 0n_T i 01_T , u 0f_T ,Such as Figure 5 shown;

[0064] Step 3: Calculate the projection coefficien...

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Abstract

The invention provides a resonant grounding system high resistance grounding fault transition resistance identification method. by using an over compensation role played by an arc suppression coil and in combination of advantages of transient signals, transient zero sequence current in a fault point is calculated and obtained by using transient zero sequence voltage of a bus and a fault line and the transient zero sequence current of any perfect feeder line, and thus, the transition resistance value is calculated. In comparison with the prior art, the zero sequence voltage of the system and the zero sequence current signal of each outgoing line are only needed, three-phase voltage and three-phase current signals are not needed, realization of the present small current grounding fault line selection device is facilitated, and influences of TV / TA transmission errors and imbalance do not exist. The technology has a wide practical application value in helping an operator with accuracy system analysis, line selection on high resistance grounding fault, positioning and distance measurement, and has important significance and important theoretical value in improving the action performance of a protective device against the transition resistance.

Description

technical field [0001] The invention relates to the field of distribution network fault detection, in particular to a high-resistance grounding fault transition resistance identification method for a resonant grounding system. Background technique [0002] Since the medium-voltage distribution network directly faces users, and single-phase grounding accounts for about 80% of the total distribution network faults, the reliable detection of single-phase grounding faults has a significant impact on power supply reliability. In China and continental Europe, most of the medium-voltage distribution network adopts the grounding method of the arc suppression coil, which is the so-called resonant grounding system. When a single-phase ground fault occurs, it is not necessary to remove the fault immediately, which is conducive to improving the reliability of power supply. However, due to the weak fault current and other reasons, it is difficult to identify the ground fault line. In re...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G01R27/08G01R31/02
CPCG01R27/08G01R31/50
Inventor 薛永端陈筱薷徐丙垠
Owner CHINA UNIV OF PETROLEUM (EAST CHINA)
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