Fault distance measurement method based on direct-current circuit breaker structure multiplexing

Abstract

The invention provides a fault distance measurement method based on direct-current circuit breaker structure multiplexing, and the method comprises the steps: employing the existing charging capacitor and inductor of a typical direct-current circuit breaker transfer branch, and forming a modified direct-current circuit breaker through adding a grounding point, a relay and an inductance element under the condition that a system loses power after fault isolation, and forming an RLC damped oscillation circuit by the modified direct-current circuit breaker and a line fault point and adopting the Prony algorithmto extract and process the discharge current to obtain the characteristic parameters of the distance measurement loop, and establishing the fault distance measurement algorithm to solve the fault distance. The method provided by the invention can accurately and reliably position fault points of a single-pole grounding fault and a double-pole short-circuit fault of the direct-current line, and is simple and clear in principle, low in sampling frequency requirement and low in construction and transformation cost.

Description

technical field [0001] The invention relates to a fault distance measurement method based on the structure multiplexing of DC circuit breakers, which belongs to the field of relay protection of DC distribution network. Background technique [0002] The medium-voltage DC distribution network based on Modular Multilevel Converter (MMC) technology has the characteristics of low switching frequency, high power quality and high reliability. Effective solutions for issues such as renewable energy generation consumption. However, the DC distribution network usually contains multiple converter stations and distributed power sources. Once a fault occurs, the fault current will rise rapidly, which will seriously affect the safe and stable operation of the entire DC distribution system. Especially when the line length of the DC distribution network is short, it becomes more difficult to locate the fault in time and accurately, and it is difficult to realize accurate fault location and...

AI Technical Summary

Problems solved by technology

However, the DC distribution network usually contains multiple converter stations and distributed power sources. Once a fault occurs, the fault current will rise rapidly, which will seriously affect the safe and stable operation of the entire DC distribution system.

Especially when the line length of the DC distribution network is short, it becomes more difficult to locate the fault in time and accurately, and it is difficult to achieve accurate fault location and distance measurement

[0003] At present, some research has been carried out on fault location of DC distribution network. According to the realization principle, the existing fault location methods can be divided into traveling wave method, fault analysis method, transient quantity method and injection method. For the ranging function, there are still problems such as the reliability and rapidity of fault ranging, which do not meet the protection requirements in the application, high sampling frequency, poor tolerance of fault ranging accuracy to transition resistance, and high construction cost of additional modules for ranging by injection method.

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