A system and method for on-line monitoring of insulation status of substation DC system

Abstract

The invention discloses an online monitoring system for the insulation state of a substation DC system. The system comprises multiple sets of DC leakage current detection devices and a signal merger and diagnosis unit. The DC leakage current detection devices are respectively used for detecting DC leakage current of all branches; each set of DC leakage current detection devices is provided with at least two DC leakage current detection devices which are used for detecting DC leakage current at different positions on the same branch respectively. The signal merger and diagnosis unit is used for detecting the voltage to earth of positive and negative buses and further wirelessly connected with all the DC leakage current detection devices to receive DC leakage current data transmitted by all the DC leakage current detection devices. The signal merger and diagnosis unit judges whether an insulation failure occurs or not and determines the position where the insulation failure occurs according to the detected voltage to earth of the positive and negative buses and the received DC leakage current data. The invention further discloses an online diagnosis method for the insulation state of the substation DC system.

Description

technical field [0001] The invention relates to an insulation state monitoring device and method, in particular to a DC system insulation state monitoring device and method. Background technique [0002] The working power supply of control systems, signal systems, and relay protection automatic control devices in power plants and substations is a DC system, which is a very large multi-branch power supply network. The insulation performance of its distribution lines is directly related to power plants, For the safe operation of substations, etc., it is of great significance to conduct on-line monitoring of its insulation and timely and effectively detect single-point grounding faults. [0003] At present, the insulation state assessment methods of DC systems mainly include balanced bridge method, differential DC method and AC method. The DC system insulation monitoring device developed based on the above method has been applied in the field. The actual operation survey resu...

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Problems solved by technology

The actual operation survey results show that the existing device is limited by the measurement principle and monitoring method, and the measurement accuracy is not high enough, and the fault location function is weak (only the entire line can be located, and there is no simultaneous detection of multiple ground points in the same branch. function), there are many shortcomings such as monitoring blind spots

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