Active power distribution network multi-terminal fault identification method and system based on transient signals

Abstract

The invention provides an active power distribution network multi-terminal fault identification method and system based on transient signals. The method comprises the following steps: firstly, transient voltage being adopted to construct a protection starting criterion; comparing the integral average value of the zero-mode voltage in the protection time window with a zero-mode setting threshold value, judging whether a grounding fault occurs or not, comparing the integral average value of the transient voltage of each phase after the zero-mode component is filtered out in the protection time window with a set threshold value, and identifying a fault phase; then, according to the fault phase and the fault type, selecting a corresponding transient signal to perform windowed Fourier transform, extracting the voltage and current of a corresponding characteristic frequency band, calculating the transient impedance under the required characteristic frequency band, and judging the fault direction by comparing the root-mean-square value of the transient impedance with the protection setting impedance value; and finally, the fault position being judged through the multi-terminal fault direction information. The method disclosed by the invention is basically not influenced by factors such as transition resistance, DG permeability, network operation state and the like, has relatively lowrequirements on communication conditions, and can realize fault identification and comprehensive protection of the active power distribution network.

Description

technical field [0001] The present disclosure relates to the related technical field of active distribution network fault identification, and specifically relates to a transient signal-based multi-terminal fault identification method and system for an active distribution network. Background technique [0002] The statements in this section merely provide background information related to the present disclosure and may not necessarily constitute prior art. [0003] As more and more distributed generation (DG) are directly connected to the distribution network, the concept of active distribution network was proposed in the 2008 International Conference on Large Power Grids (CIGRE). Renewable energy, low line loss, flexible and reliable power supply and other advantages are considered to be the development direction of smart distribution network. However, the access of DG poses new challenges to distribution network relay protection. Since the traditional distribution network...

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Problems solved by technology

For the third type of method, current differential protection is affected by data or equipment synchronization, and the current distribution network does not have additional synchronous data channels or GPS equipment; such as the longitudinal protection method based on the positive sequence current mutation phase, this method First, the fault direction is judged by the phase characteristics of the positive sequence current mutation, and then the protection devices on both sides send fault direction information to each other. When the devices on both sides of a certain section judge that a positive fault occurs, the section is considered to be a faulty section

This method does not require strict time synchronization, but in the case of large fault resistance and load, there may be through current in the fault line, which will affect the accuracy of fault direction judgment

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