Highly reliable Coordinated Control Strategy for Static Frequency Converters applied to Large Synchronous Condensers

Abstract

A large synchronous condenser can quickly and flexibly implement various functions such as dynamic change in load tracking, realization of peak reduction and valley filling, emergency reserve, frequency modulation, and phase modulation. This type of condenser is typically started using a static frequency converter (SFC). Based on the analysis of the working principle of SFCs, this paper proposes a highly reliable coordinated control method with resynchronization criterion for an SFC. An auxiliary loop is introduced for voltage control at the SFC to realize feedforward of the trigger angle of the rectifier. This method can effectively improve the success rate of grid synchronization of the synchronous condenser and shorten the start-up time. Moreover, when the AC voltage on the grid side drops, the auxiliary ring can automatically reduce the terminal voltage to maintain a stable operation. A comparative experiment was conducted on an RTDS to verify the feasibility and effectiveness of the proposed method.