A Scheme of Controlled Switching System in Converter Station

For the past few years, in the HVDC (high voltage direct current transmission) and UHVDC (ultra high voltage direct current transmission) projects, the circuit breaker closing resistor failure has occurred many times, which has adversely affected the safety and stability of operation. For the switching operation of AC filter and converter transformer in converter station, the controlled switching system can improve the on/off transient process of circuit breaker, as well as avoiding the impact on power equipment and power grid when the closing resistor is cancelled. Based on plenty of the implementation and testing experience of controlled switching system in converter stations, the composition of controlled switching system and technical requirements, circuit breaker matching and functional test are presented briefly. This paper focuses on the controlled switching applications of filter banks and converter transformers, summarizes the control strategy, the commissioning requirements of controlled switching system, and the key problems in engineering and equipment operation and maintenance, so as to provide reference for relevant technical personnel. A special transformation scheme of eliminating closing resistor and adding controlled switching is introduced in this paper. This scheme has been implemented in several projects and proven effective.