mmc-upfc system and its series side converter outage method

Abstract

The invention relates to an MMC-UPFC system and a shutdown method for serial side converters of the MMC-UPFC system. The system comprises at least one parallel side transformer, a parallel side converter, two serial side transformers and two serial side converters. Each parallel / serial side converter is connected with the secondary side of a corresponding parallel / serial side transformer. The method comprises the steps of 1), simultaneously reducing output voltages of the serial side transformers connected with the serial side converter of the corresponding circuit to 0, and latching and controlling power flow of a current circuit; 2), switching on bypass switches of the primary sides of the serial side transformers in sequence; 3), simultaneously transferring all power flow of each circuit to the corresponding bypass switches; 4), latching the serial side converter of each circuit, thereby shutting down the serial side converters. According to the system and the method, before the converters exit, the power flow is stably risen and reduced to the natural power flow, the current shock generated when the bypass switches are switched on can be effectively inhibited; the power flow oscillation of an alternating current circuit can be reduced, and a uniform power flow controller of double circuits can be shut down stably.

Description

technical field [0001] The invention relates to power electronics and flexible AC transmission technology, in particular to an MMC-UPFC system and a method for shutting down converters on the series side thereof. Background technique [0002] With the rapid development of the power system, its operational flexibility, controllability and stability have become more and more urgent problems to be solved; large-scale distributed energy sources such as solar energy and wind power are connected to the power system, which further increases the security of the system. The complexity of power flow regulation. In addition, there are many long-distance transmission lines in my country, and the power grid structure is relatively weak. It can improve the power transmission capacity of existing lines and maximize the transmission capacity of the power grid; improve the transient stability of the power system and damp system oscillation; optimize the power flow and reduce circulation. Red...

AI Technical Summary

Problems solved by technology

[0005] The present invention provides an MMC-UPFC system and its outage method for series-side converters to solve the problem of coordinated outage mode for series-side converters lacking a unified power flow controller for double-circuit or multi-circuit lines in the prior art

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