MMC converter DC power distribution network single-pole high-resistance grounding fault protection method

Abstract

The invention discloses an MMC converter DC power distribution network single-pole high-resistance grounding fault protection method, which mainly comprises the following steps of: judging whether a single-pole grounding fault occurs or not by taking the change rate of positive and negative pole voltages to ground of a DC power distribution network as a starting criterion and taking the voltage variation as a fault criterion; when a single-pole grounding fault occurs, firstly, determining a fault pole according to the magnitude of positive and negative pole voltages; preliminarily judging a fault line according to the magnitude and the direction of the fault electrode charging and discharging current detected at the head end of each line; and finally, injecting a detection signal into the fault electrode, and verifying the accuracy of the judgment according to the size of the detection signal detected at the head end of each line. When the two data are consistent, determining that the line is the fault line; and when the two data are inconsistent, re-determining the fault line by using the charging and discharging current criterion and the detection signal criterion and using a comprehensive weight method.

Description

technical field [0001] The invention belongs to the technical field of relay protection for electric power systems, and in particular relates to a unipolar high-resistance grounding fault protection method for a DC distribution network of an MMC converter. Background technique [0002] When the DC side of the DC distribution network based on the MMC converter is mostly sampled through the grounding mode of the clamp resistor, the fault current is small and the inter-pole voltage basically remains unchanged when a single-pole ground fault occurs. Therefore, in the DC distribution network The application is more extensive. In the DC distribution network, especially the DC distribution network through the clamping resistor, when a single-pole ground fault occurs, the fault characteristics are not obvious, and the resistance of the fault point varies in a large range, so that the single-pole ground fault protection has always been one of the relay protection methods. difficulty...

AI Technical Summary

Problems solved by technology

Due to the complex fault characteristics and many types of faults when a single-pole ground fault occurs in the DC distribution network, the fault component is relatively small, which seriously affects the accuracy of single-pole ground fault protection.

[0003] However, at present, the protection of DC distribution network is still in the stage of theoretical research, and factors such as the imperfection of DC protection equipment have caused huge constraints and challenges to the protection of DC distribution network.

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