中高压直流开断技术

DC power grid has wide application prospects in the high-voltage flexible transmission as well as in the access to new energy, track traction, and the future urban distribution networks. As the crucial equipment for the control and protection, DC circuit breaker is an important guarantee for the DC grids security. Compared with AC interruption, DC interruption has higher requirements and its implementation is more difficult. According to the differences of breaking principles and methods, there are mainly three types of DC circuit breaker (DCCB), i.e., air DCCB, current injection DCCB, and hybrid DCCB. These DCCBs are reviewed in detail, including the introduction of principles and operations of breaking concepts and the analyses on the latest technological achievements in the breaking of medium-voltage (MV) and high-voltage (HV) DC current. The air DCCB realizes the current breaking by producing a sufficiently high arc voltage, which has been widely used in the low-voltage applications for its simple structure and high reliability. The current injection DCCB achieves the current breaking by injecting a counter current from the energy-storage components, and it has relatively short breaking time and is suitable for MV and HV DC system. The hybrid DCCB utilizes the full-controlled power electronic switches to forcedly cut off the current, which has the favorable properties in the rapid breaking process and is adaptable for various voltage classes. However, the relative high cost of hybrid DC breaker restricts its application.