Distributed power generation system and island detection device thereof, current converter thereof

Abstract

The invention discloses a distributed power generation system and island detection device thereof. The distributed power generation system comprises a grid-connected current converter, an input source providing the electric energy for the grid-connected current converter, a grid-connected switch that is connected between the output side of the grid-connected current converter and the grid, a point of common coupling that is located between the grid-connected current converter and the grid-connected switch, a load connected to the point of common coupling, a capacitor module consisting of a plurality of capacitors, a switching module and an island detection device; wherein one end of the switching module is connected with the capacitor module, the other end of the switching module is connected with the point of common coupling; when the switching module is closed, the capacitor module is connected with the point of common coupling; when the switching module is opened, the capacitor module is disconnected with the point of common coupling; the island detection device is used to acquire the resistance value at the point of common coupling and compare the acquired value with the resistance threshold value. If the acquired resistance value is larger than the resistance threshold value and the duration thereof exceeds the preset time length, then it is determined that the island effect occurs.

Description

technical field [0001] The present application relates to the technical field of grid-connected power generation, and in particular to a distributed power generation system, an islanding detection device, and a converter thereof. Background technique [0002] In the existing power supply system, when the grid interrupts the power supply due to faults and other reasons, the entire system will form an island disconnected from the grid with the surrounding loads. If there are grid-connected converters or other grid-connected power generation equipment in the power supply system, it may cause damage to the equipment and threaten the personal safety of the staff. Therefore, it must be able to detect quickly when the island state occurs. [0003] Traditional islanding detection methods are divided into two types: passive and active. Passive detection is mainly to judge the islanding effect on the change of Point of Common Coupling (PCC) voltage or frequency in the power supply sy...

AI Technical Summary

Problems solved by technology

This method has high detection accuracy and small detection blind area, but the control is relatively complicated

For example, the active disturbance current injection method is used in the grid-connected power generation equipment, which leads to an increase in the harmonic content of the output current of the converter, and reduces the efficiency of power generation of the grid-connected equipment in the system

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