混合式高压直流断路器的控制策略与实验研究

现有的高压直流断路器能够在几十ms内断开电路，但对于高压直流输电系统，远不能达到要求。基于半导体的高压直流断路器能克服动作速度上的问题，但需要大量电力电子开关器件串并联，有很高的技术难度，同时会产生大量损耗。为了克服上述缺点，采用一种混合式高压直流断路器的拓扑结构。首先介绍了断路器开通和关断的原理，接着提出一种故障预处理的控制策略，在故障发生时提前进行换流，从而缩短故障发生后线路开断的时间；最后利用PSCAD进行建模仿真，制作了单元样机进行降压实验。仿真和实验结果证明：在系统发生短路的情况下，混合式直流断路器能够快速开断短路电流，还可以在直流线路分断后为直流线路及负载中储存的能量提供释放回路。

Control Strategy and Experimental Study of Hybrid HVDC Circuit Breaker

Existing HVDC circuit breakers are capable of interrupting HVDC currents within several tens of milliseconds, but this is too slow to fulfill the requirements of a reliable HVDC grid.HVDC breakers based on semiconductors can easily overcome the limitations of operating speed,but need large number of the series （parallel ） connection of electronic switching devices;at the same time, it requires high technology and generates a lot of loss. To overcome these shortcomings,a topology of hybrid HVDC circuit breaker was introduced.Firstly,this paper described the principle of hybrid HVDC circuit breaker;then a control strategy of fault pretreatment was also proposed,that was the pre-action of the converter when fault occurred,in order to improve the breaking speed of the hybrid circuit breaker;at last the modeling and simulation were carried out on the hybrid HVDC circuit breaker by PSCAD,and unit prototype was made for the step-down experiments.The simulation and experimental results prove that：when a short circuit occurs,the hybrid HVDC circuit breaker can quickly break the short-circuit current;and the buffer circuit can be provided for the release of the stored energy circuit in DC circuit and load.