Zero-sequence circulating current suppression method, device, and grid-connected inverter parallel system control method

Abstract

The invention discloses a zero sequence current inhibiting method, an apparatus, and a grid-tie inverter parallel system controlling method. The method is performed through the following steps: determining a first phase compensation, a second phase compensation and a third phase compensation according to the connection time and the disconnection time within a switch period of a bridge arm power device; determining the zero sequence compensation according to the duty ratio of the bridge arm power device within a period; compensating the obtained compensations of different phases respectively into the bridge arm power device to make it basically consistent between the connection state and the disconnection state; and compensating the obtained zero sequence compensation into bridge arm power device to make the connection and disconnection of the bridge arm power device lasts almost same period. Such designs raise the consistency among the inverter power devices and effectively inhibit zero sequence current.

Description

technical field [0001] The invention relates to the field of communication technology, in particular to a zero-sequence circulating current suppression method and device, and a control method for a grid-connected inverter parallel system. Background technique [0002] At present, with the increase of the grid-connected power of the power station, the power level requirements of the grid-connected inverter are also increased. In order to reduce the requirements of the power station for the power device level of the grid-connected inverter, the parallel operation of the inverter has become a research hotspot. [0003] The grid-connected inverter parallel system with a common DC bus is widely used, but because of the zero-sequence circulating current in this topology, and the zero-sequence circulating current flows between the subsystems of the parallel system, it is easy to cause harm to the inverter and reduce the operating cost of the system. Therefore, it is necessary to ta...

AI Technical Summary

Problems solved by technology

The circulation path of zero-sequence circulation is as follows: figure 1 shown, namely P-S11-A1-A-A2-S42-N-P, by figure 1 It can be seen that the zero-sequence circulating current does not pass through the power grid, but only flows in each sub-inverter system of the parallel system, without load consumption, so a small zero-sequence voltage difference can form a large zero-sequence circulating current, causing great damage to the parallel system. the harm of

Images