Ground fault detection and calibration method and device for direct current system

Abstract

The problem of correct wire selection of a branch with a ground fault of a direct current system of a power system is always a difficult problem for the power system. Comprehensive reasons on a plurality of aspects cause the phenomenon that the correct wire selection is difficult. The safety and the reliability of the direct current system affect the operation of power plants and transformer stations and are related to the safe production of the whole large power system. The ground fault detection and calibration method and the device for the direct current system improve the insulation supervision alarm value of a bus to the level of 100KO from 48KO. The ground fault detection and calibration method and the device are based on the requirements of (DL/T5044-95) technical regulations for design of direct current systems of fossil fuel power plants and transformer substations, and the corresponding branch insulating detection ability is improved to the level of 300KO from 20KO, and the branch insulating detection horizontally covers all the fault phenomena of the insulating alarm value of the direct current system. The calibration method and the device are used for detecting the calibration of a direct current insulating supervision device before access network. The invention aims at ensuring the safety of the system and the standards of access network.

Description

technical field [0001] The invention relates to a method for detecting and calibrating a DC system grounding fault in a power system, and belongs to the application category of DC system detection equipment. Background technique [0002] 1. The current monitoring level of DC system busbar insulation: [0003] DC power supply is one of the important power sources in power plants and substations. At present, the monitoring of DC bus insulation is based on the insulation monitoring current of 1.4mA. When the leakage current is greater than 1.4mA, the overall insulation level of the DC system has dropped below 48kΩ, and the resolution and accuracy of the DC bus insulation monitoring are judged. Ground fault, the basis for starting the next step of work. The current theoretical calculation is able to detect the phenomenon that the busbar insulation is less than 48KΩ, and the detection ability of the actual busbar insulation is less than the theoretical calculation value. [00...

AI Technical Summary

Problems solved by technology

In operation practice, it has been found that DC grounding will not only cause misoperation or refusal of relay protection, but may even cause misoperati

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