High resistance grounding detection system, device and method for small current grounding system

Abstract

The invention discloses high resistance grounding detection system, device and method for a small current grounding system. The system comprises a grounding wire selecting device, a flexible voltage source and a boosting transformer, wherein the grounding wire selecting device is connected with the flexible voltage source, a high voltage side of the boosting transformer is connected between a neutral point of the system and the ground, and a low voltage side of the boosting transformer is connected with the flexible voltage source; and the flexible voltage source is used for receiving commandsissued by the grounding wire selecting device and emitting an appointed voltage vector to the low voltage side of the boosting transformer. The method comprises the following steps: when a groundingfault does not occur, injecting a non-power frequency voltage through the neutral point, collecting a bus zero sequence voltage and a zero sequence current of each branched circuit, and calculating the zero sequence capacitive reactance of each branched circuit; and when a grounding fault occurs, calculating power integration and a resistance value of a grounding point according to the zero sequence capacitive reactance of each branched circuit, a collected bus three-phase voltage, the zero sequence voltage and the zero sequence current of each branched circuit, and selecting a grounding wire.The invention further discloses a corresponding high resistance grounding detection device. According to the system, the device and the method, the high resistance grounding recognition capacity of the small current grounding system is improved.

Description

Technical field [0001] The invention relates to the field of relay protection of electric power systems, in particular to a high-resistance grounding detection system, device and method for a small current grounding system. Background technique [0002] In the 3kV-66kV low current grounding system, single-phase grounding is a common type of fault. When a single-phase grounding occurs in a small current grounding system, the fault phase-to-ground voltage decreases, and the non-fault phase-to-ground voltage increases, and the line voltage is still symmetrical. In this state, because the ground current is small, in order to ensure the reliability of power supply, operation is allowed 1- 2h. However, due to the arc overvoltage of the non-fault phase, it is easy to cause the breakdown of the weak part of the insulation, the saturation of the voltage transformer core, the system overvoltage, and the arc of the fault phase burns the cable, and is easy to cause personal electric shock a...

AI Technical Summary

Problems solved by technology

[0004] The purpose of the present invention is to provide a high-impedance grounding detection system, device and method for a small-current grounding system, so as to solve the problem that the current low-current grounding system cannot accurately select a line when a single phase is grounded through high-impedance

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