Improved intermittent reactive power disturbance island detection method

Abstract

The invention discloses an improved intermittent reactive power disturbance island detection method. The method applies periodic reactive power disturbance on an inverter controller, and each reactive power disturbance period is divided into reactive power disturbance time and non-reactive power disturbance time. At the starting time of each reactive power disturbance period, the voltage frequency detected by a frequency detection module is bestowed on a reactive power disturbance quantity calculating module, the minimum reactive power disturbance quantity required for the period is then calculated by the reactive power quantity calculating module, the reactive power disturbance quantity can ensure that the frequency of a common coupling point deviates out of an allowed range when an island phenomenon occurs, an intermittent reactive power disturbance signal module generates an intermittent reactive power disturbance signal of the period according to the calculated reactive power disturbance quantity, and periodic intermittent reactive power disturbance is applied on the inverter controller so as to achieve the purpose of detecting the island. According to the improved intermittent reactive power disturbance island detection method, the island phenomenon can be timely and effectively detected, the reactive power disturbance quantity required for the island detection can be reduced, and the influence on the grid-tied power factor is smaller.

Description

technical field [0001] The invention relates to an islanding detection technology in the application field of a distributed power generation system and a grid-connected inverter, in particular to an islanding detection method for intermittent reactive power disturbance without improvement. Background technique [0002] Due to the rapid consumption of non-renewable energy such as fossil energy and the increasingly serious environmental problems, new energy distributed power generation has gradually received extensive attention. In the new energy distributed power generation, the electric energy generated by wind energy, photovoltaic, fuel cell, etc. is converted into qualified electric energy by power converter and incorporated into the grid. As an interface between new energy sources and the grid, grid-connected inverters can transform electric energy and control power quality. Usually distributed generation systems include single-phase or three-phase grid-connected inverte...

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Problems solved by technology

However, the traditional reactive power disturbance method will introduce a large amount of disturbance to the reactive power output by the grid-connected inverter and reduce the output power factor of the inverter, which has relatively large defects.

[0006] The external communication detection method detects the occurrence of islanding by establishing a communication link between the power grid and the distributed generation device, but the high cost limits the application of the external communication detection method

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