Island detection method and device for electrical power device

Abstract

The invention discloses an island detection method and device for an electrical power device. The method includes the steps that the actual working frequency f0 of a power distribution system is obtained, and a corresponding power frequency period T is calculated according to the formula T=1 / f0; then the sampling frequency fc of the point of common coupling (PCC) of the power distribution system and a distributed power supply or a microgrid is obtained; according to the sampling frequency fc, the power frequency period T is divided into N time periods, and the formula N= fc / f0 is met, wherein the formula delta t =T / N=1 / fc is met; corresponding voltage sampling data u(n delta t) (n=0,1,2...,N) of the PCC in each time period n delta t (n=0,1,2...,N) are collected; integral operation is performed on the voltage sampling data to obtain integral values L, and the formula of L is expressed in the specification; L is compared with the threshold value beta of the island phenomenon, and if L is larger than beta, it is proved that the island phenomenon happens. The detection method is not affected by conventional interference factors in the detection process, and the integration of the whole power frequency period starting from any time can serve as a judgment criterion; only one power frequency period is needed for obtaining a judgment result, the detection speed is high, and the island detection method and device are beneficial for rapidly isolating faults and guaranteeing operation reliability of the power distribution system.

Description

technical field [0001] The invention relates to the field of electric power, in particular to an islanding detection method and an islanding detection device for power supply equipment. Background technique [0002] At present, distributed power generation represented by wind power and solar power generation has attracted extensive attention from academia and industry due to its advantages of flexibility, low carbon and environmental protection. At the same time, the penetration rate of distributed power generation in power distribution systems is increasing year by year. . Distributed power can be connected to the power distribution system in a decentralized manner, and can also be connected to the power distribution system in the form of a microgrid. For power distribution systems, most distributed power sources are uncontrollable power sources, and their output power is often affected by natural conditions and has strong random characteristics. In order to ensure the re...

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Problems solved by technology

This zero-crossing detection method has a high detection accuracy when the measured waveform is relatively smooth, and the power grid will inevitably be affected by various disturbances such as load changes, component switching, and motor startup during actual operation, so that the detection point The voltage waveform is distorted and glitches are generated. In this way, several voltage zero points may be continuously detected before and after the power frequency voltage zero crossing point, resulting in inaccurate or even wrong phase detection, which can easily lead to the malfunction of the island detection unit, thereby affecting the reliability of the distribution system run

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