Islanding Detection Method Based on Voltage Harmonic Sequence Components

Abstract

The invention discloses an island detection method based on voltage harmonic sequence components. A sliding data window is used to calculate the variation values, |delta U2(1)|, |delta U2(2)|, |delta U4(1)| and |delta U4(2)|, of positive and negative sequence components of the specific voltage subharmonic of a grid-connected inverter terminal, and whether islanding occurs is determined according to the variation values, |delta U2(1)|, |delta U2(2)|, |delta U4(1)| and |delta U4(2)|. The purpose is to detect the islanding effect quickly and effectively without affecting the power quality of a power system. The island detection method has the advantages of simple principle and wide application range, and islanding under various circuit breaking conditions and the most serious islanding conditions can be quickly and effectively detected.

Description

technical field [0001] The invention belongs to the technical field of grid connection of distributed power sources, and in particular relates to an islanding detection method based on voltage harmonic sequence components. Background technique [0002] The island effect refers to that in the distributed power generation system, when the grid power supply trips due to power outage maintenance or fault accidents, the distributed grid-connected power generation system at each user end fails to detect the power outage in time and cut itself off from the city. Finally, a grid-connected power generation system of distributed power stations and its connected loads form a self-supplied island power generation system. [0003] Islanding can liven up lines that are thought to be disconnected from all sources, posing a risk of electric shock to grid maintenance personnel or users. Therefore, it is necessary to quickly and effectively detect the islanding effect and remove the fault. ...

AI Technical Summary

Problems solved by technology

Local islanding detection methods can be further divided into two types: passive and active. The passive method only judges the occurrence of islanding based on the abnormal voltage or frequency output by the grid-connected inverter. Usually, the passive method has relatively large detection blind spots; while the active The traditional method injects disturbances into the power grid, and uses the corresponding changes in system voltage, frequency, and impedance caused by the disturbance signals to judge the occurrence of islands. Although this method can effectively reduce detection blind spots, it will have certain impact on power quality. influences

[0008] The second type of communication-based islanding detection method mainly uses radio communication to detect the islanding effect. This method can reduce the detection blind area, but the design is complicated and has not been widely used.

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