Proactive Hybrid HVDC Breakers - A key innovation for reliable HVDC grids

摘要

Existing mechanical HVDC breakers which are capable of interrupting DC currents within severaltens of ms are too slow to fulfil the requirement of a reliable DC grid. Semiconductor based DCbreakers easily overcome the limitations in operation speed but generate large transfer losses typicallyin the range of 30% of the losses of a voltage source converter station.To overcome these obstacles a hybrid HVDC breaker is proposed in this paper. The alternative designhas negligible conduction losses while preserving fast current interrupting capability. By intelligentinternal control, the same performance regarding clearing a DC fault can be obtained as with a pureIGBT DC breaker.This paper presents a detailed description of the proposed hybrid DC Breaker, its design principles andproactive control with particular focus on the reliability of the concept. The modular design of thehybrid DC breaker for HVDC applications is described and results from prototype testing arepresented. Furthermore, the application of the hybrid DC breaker associated with the design of a DCswitchyard is discussed.