Composite type island detection method based on phase deviation and frequency variation

Abstract

The invention discloses a composite type island detection method based on phase deviation and frequency variation. Firstly, delta theta1 and delta theta2, the motion values of two phase deviations areset, and the condition that delta theta1 is more than delta theta2 is met; when the phase deviation angle of the end voltage of a distributed generator (DG, Distributed Generator), delta theta is more than delta theta1, DG is directly judged as island operation; when delta theta is more than delta theta2 and less than delta theta1, the frequency variation value delta f is introduced as supplementary detection amount, only when the condition that delta theta is more than delta theta2 and delta f is less than delta f1 is met, delta f1 is frequency variation motion value, so that the motion of the detection device is judged as island state; the composite type motion criteria of the island detection are concluded as follows: delta theta is more than delta theta1(1) or delta theta is more thandelta theta2 and delta f is less than delta f1(2); the criterion (1) is used for island instant DG and the condition that mismatching degree of loaded active power is larger, while the criterion (2)is used for the condition that the change of the loaded active power carried by island post DG is not large, namely, the traditional phase deviation method can not detect the island state; whether DGis in the island state or not is judged by introducing frequency variation amount and combining the phase deviations and frequency variations.

Description

technical field [0001] The invention relates to the technical field of distribution network protection and control and the technical field of distributed power generation, and more specifically relates to a composite islanding detection method based on phase offset and frequency variation of a distributed synchronous generator. Background technique [0002] Grid-connected distributed power sources need to be installed with an island detection device to quickly and accurately detect the island state. Once the island occurs, take corresponding measures immediately to eliminate the possible harm caused by the island operation. Due to the different types of distributed generators (DG, DistributedGenerator) and their grid connection methods, the islanding detection methods are also different. For synchronous generators, a passive detection method based on changes in local (DG side) electrical quantities is generally used. Among them, islanding detection using DG terminal voltage...

AI Technical Summary

Problems solved by technology

The contradiction between sensitivity and misoperation cannot be solved only by detecting phase shift

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