DC power distribution network grounding fault line selection method and system

Abstract

The invention discloses a DC power distribution network grounding fault line selection method and system. The method comprises the steps of: starting MMC additional control by using a bus voltage imbalance criterion, and injecting a detection signal; collecting a positive electrode current and a negative electrode current of the head end of each feeder line by delaying delta t; filtering the positive electrode current and the negative electrode current of the head end of each feeder line, and setting the center frequency fmp as the characteristic frequency of the detection signal to obtain the filtered positive electrode current and negative electrode current of the head end of each feeder line; solving a zero-mode current of each feeder line for the filtered positive and negative electrode currents of the head end of each feeder line, carrying out normalization processing, and summing to obtain a reference current; and calculating waveform correlation between the normalized feeder zero-mode current and the reference current one by one, carrying out fault judgment according to a Pearson correlation coefficient to determine a fault line and a sound line, and completing grounding fault line selection of a DC power distribution network. The DC power distribution network grounding fault line selection method effectively enhances fault features, avoids installation of additional devices, and has the advantages of high sensitivity and no need of double-end communication.

Description

technical field [0001] The invention belongs to the technical field of distribution network fault identification, and in particular relates to a method and a system for selecting a grounding fault line of a DC distribution network. Background technique [0002] With the rapid development of power electronics technology and its wide application in power systems, DC distribution network has been widely studied because it is easy to realize new energy access and improve power quality. The main topological structures of the DC distribution network include radial, two-end hand-in-hand and ring structures. Among them, the radial structure has become the most commonly used structure in the current engineering practice due to its advantages of low investment cost. [0003] The medium-voltage DC distribution network mostly adopts a pseudo-bipolar structure, and the DC side is grounded through a clamping resistor. This grounding method is to enable the system to continue to operate wi...

AI Technical Summary

Problems solved by technology

The existing method has low sensitivity and insufficient reliability, and the ground fault line selection method of the traditional AC small current grounding system is difficult to learn from in the flexible DC distribution network with a large number of distributed power sources and energy storage equipment. Therefore, it is urgent to study new Single-pole ground fault identification method for flexible DC distribution network

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