Quick intelligent anti-island system and quick intelligent anti-island method with power grid fault self-recovering capability

Abstract

The invention provides a quick intelligent anti-island system and a quick intelligent anti-island method with power grid fault self-recovering capability. The method comprises the steps of a first step, establishing the main circuit of a distributed power generating grid-connected system; a second step, injecting phase angle fluctuation in the control circuit of the grid-connected system by an active phase deviation module; and a third step, based on the voltage signal of a common connecting point in the grid-connected system and a power grid frequency signal which is obtained by a phase-locked loop, realizing island detection and power grid fault self-recovering, wherein the common connecting point is the accessing position of a grid-connected filter and a local load into the power grid. The quick intelligent anti-island system and the quick intelligent anti-island method can quickly detect the island, and adding of additional hardware such as sensor is not required in the distributed power generating grid-connected system in which the phase-locked ring is used for realizing power grid synchronization. On the extreme condition that the system local load is a parallel RLC load which matches the power of the distributed power generating system, operation state of the island can be quickly and accurately detected. Furthermore no detection blind area exists and system operation efficiency can be effectively improved.

Description

technical field [0001] The invention relates to the field of anti-islanding protection of a distributed power generation grid-connected system, in particular to a fast and intelligent anti-islanding system and method with power grid fault self-healing capability. Background technique [0002] With the depletion of fossil energy, solar energy, wind energy, fuel cells and other new energy sources have been widely developed and used. These distributed power generation equipment are connected to the grid through power converters to transmit electric energy to the grid. For the distributed generation grid-connected system, there is a security risk of the island effect. The island effect refers to the phenomenon that in a distributed power generation grid-connected system, when the main grid is cut off due to maintenance or failure, the power generation equipment continues to supply power to the load, forming a power supply island. [0003] If the island effect cannot be detecte...

AI Technical Summary

Problems solved by technology

[0004] (1) Since the power grid system is equipped with an automatic reclosing device, if the power generation system does not have anti-islanding capabilities, it is very likely that the power generation device and the power grid will be out of sync when the system recloses, and a large inrush current may occur , damage circuit breakers and power generation devices, and even cause the power grid to trip again;

[0005] (2) Due to the isolated island state, the system runs away from the grid, which is prone to voltage and frequency out of control

If the power generation device does not have the ability to adjust voltage and frequency, nor does it have the ability to cut out the island state in time, it may cause large voltage and frequency fluctuations, which may damage the power grid and electrical equipment;

[0006] (3) When a grounding or phase-to-phase short-circuit fault trips in the power grid, the islanding effect will hinder the removal of the fault and interfere with the automatic or manual recovery of the power grid;

[0007] (4) When the power grid is tripped and repaired, the island effect will make the line disconnected from the main power grid still live, which will pose a threat to the safety of maintenance personnel

However, the existing anti-islanding methods do not have self-healing capabilities. After the anti-islanding action of the distributed generation grid-connected system, it needs to be manually judged before it can be connected to the grid again.

This not only increases the maintenance workload of the distributed generation grid-connected system, but also reduces the operating efficiency and economic benefits of the power generation system

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