Method for detecting island by intermittent two-sided reactive power disturbance

Abstract

The invention discloses a method for island detection by adopting intermittent two-sided reactive power disturbance. A frequency of a voltage of a common coupling point is out of allowance range after an island occurs by introducing the intermittent two-sided reactive power disturbance into the output reactive power of a grid-connected inverter, so that the aim of the island detection is fulfilled. By the method, an island phenomenon can be detected immediately and effectively, and grid-connected power factors are less influenced.

Description

technical field [0001] The invention relates to an island detection technology in the application field of a distributed power generation system and a grid-connected inverter, in particular to an island detection method for intermittent bilateral reactive power disturbances. Background technique [0002] In the new energy distributed power generation, the electric energy generated by wind energy, photovoltaic, etc. is integrated into the grid after power electronic conversion. As an interface between new energy sources and the grid, grid-connected inverters can transform electric energy and control power quality. Generally, the grid-connected inverter system includes a single-phase or three-phase grid-connected inverter controlled by pulse width modulation based on high-frequency switches, a transformer used for electrical isolation between the inverter and the grid, and a transformer used for grid-connected inverters Controlled relays, local loads, power grids and grid-con...

AI Technical Summary

Problems solved by technology

[0004] (1) After disconnecting from the grid, the distributed generation device may be damaged due to voltage or frequency out of control;

[0005] (2) Local electrical equipment may be damaged because the voltage or frequency in the island exceeds the safe range;

[0006] (3) Posing a certain threat to personal safety;

[0007] (4) When the island is isolated, if the capacity of the local load is too large, the distributed power supply will be damaged due to overload;

[0008] (5) When the power grid recloses, because the voltage amplitude, frequency and phase of the distributed power supply in the island are inconsistent with the voltage amplitude, frequency and phase of the power grid, the closing fails

However, this type of method is difficult to implement and the cost is relatively high

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