Islanding detecting method

Abstract

The invention discloses an islanding detecting method which comprises the following steps: acquiring a voltage waveform of a common coupling point and measuring a frequency value, calculating the average change rate in a certain period to obtain a judging signal, comparing the judging signal with the preset change rate threshold value, outputting a control signal, selecting an outputted reference signal of an inverter by the control signal, introducing reference current after phase deviation under the condition that islanding possibly exists by a frequency change rate detection method, realizing further detection according to a sliding mode frequency deviation method, otherwise, introducing non-deviation reference current, and achieving normal operation of the system. The islanding detecting method has the advantages of reducing detection blind zones and impact on the system power quality and increasing the detection speed.

Description

technical field [0001] The invention relates to the technical field of distributed power generation island detection, in particular to an island detection method. Background technique [0002] Today's distributed energy development depends to a certain extent on the operating conditions and protection systems of distributed power generation systems. The integration of distributed generation into the grid has created many problems, one of which has been widely studied is the islanding phenomenon. Islanding is the state in which the load is self-sufficiently powered by the distributed generation system after the grid is disconnected. Unplanned islanding can cause serious damage to power supply and distribution equipment and consumers, and can be a safety threat to grid maintenance personnel. Therefore, in the protection equipment of the distributed generation system, the function of island detection is essential. At present, various detection methods proposed by domestic an...

AI Technical Summary

Problems solved by technology

Active methods mainly include sliding mode frequency shift method (SMS), active frequency shift method (AFD), Sandia frequency shift method (SFS), etc.; but compared with passive methods, it will reduce power quality and increase detection time

Combining active and passive methods to form a hybrid detection method can not only have the advantages of both active and passive methods, but also overcome their respective shortcomings. However, the current research on effective hybrid detection methods is not deep enough.

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