Inverter disturbance type island detection method based on combination of voltage frequency and measured impedance

Abstract

The invention relates to the technical field of power system analysis and in particular relates to an inverter disturbance type island detection method based on combination of voltage frequency and measured impedance. The method is characterized by comprising the following steps: firstly analyzing island after-frequency reactive relation; controlling setting frequency-reactive feedback method inverters, and adding a feedback coefficient; if the sum of reactive power output by each inverter is not equal to zero, detecting whether an island operation state occurs or not according to the condition that whether the voltage frequency of a gird-connected inverter exceeds the limit of normal operation or not; otherwise, intensively injecting a voltage source signal at the point of common coupling of a system, wherein the signal is a single frequency signal, and the injection mode is three-phase injection; and detecting whether the island operation state occurs or not through the characteristic difference of system measurement impedance at the point of common coupling of the system. The island detection method provided by the invention can avoid failure caused by mutual interference of multiple disturbance signals in multi-inverter system scenes, and has the advantages of relatively high reliability, relatively high detection speed and simple and effective principle.

Description

technical field [0001] The invention relates to the technical field of power system analysis, in particular to an inverter disturbance islanding detection method based on the combination of voltage frequency and measured impedance. Background technique [0002] In the world, the conventional fossil energy is depleting day by day, and the environmental pollution problem is attracting people's attention day by day. Therefore, the governments of various countries pay more and more attention to the development of renewable energy. More and more distributed power sources such as photovoltaic systems are connected to the distribution network. With the gradual increase in the capacity of distributed power sources, the power distribution system has changed from a radial network with one-way flow of power to a multi-directional network with two-way power flow. A complex network of power and grid interconnections. As a result, the problem of grid-connected protection of distributed p...

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Problems solved by technology

However, with the development of the system to diverse time-varying loads and multi-inverter grid connection, the interaction of disturbance signals of each inverter in the active method leads to the failure of islanding detection. Therefore, it is necessary to carry out active detection based on traditional inverter disturbances. Research on the Island Detection Method for Method Failure Problem

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