基于故障限流器的直流多馈入受端系统动态分区技术

Fault Current Limiters Based Dynamic Segmentation Technique for Multi-infeed HVDC Systems

为提升直流多馈入受端系统的运行性能,提出一种基于故障限流器的电网动态分区技术。该技术的基本思想是根据网架结构,选择合适的交流线路安装故障限流器,从而将系统划分为若干个相互之间由故障限流器隔开的区域。在正常情况下,故障限流器等效阻抗为0,不会影响系统的潮流分布和电压水平;当交流系统发生短路故障时,故障限流器将投入限流阻抗以限制短路电流,阻隔故障在各区域电网之间的传递,从而有效缩短直流线路换相失败的持续时间,加快直流功率恢复,缓解多回直流线路同时换相失败引起的交流系统功率不平衡和潮流转移问题,提升整个系统的暂态稳定性。以2个典型结构的直流多馈入受端系统为例,验证上述分区技术的有效性。

In order to improve the performance of the multi-infeed HVDC systems, a grid dynamic segmentation technique based on the fault current limiters was proposed in this paper. The basic idea of the technique was to install the fault current limiters on the appropriate AC lines according to the network structure and to segment the power grid into a number of sectors connected by these fault current limiters. The equivalent impendence of the fault current limiters is zero under normal conditions and does not affect the power flow and the voltage of the system. When short-circuit faults occur inside the AC system, the current-limiting impendence is inserted to limit the short-circuit current and obstruct the propagation of the faults among the sectors. As a result, the commutation failure duration of the DC systems is shorten, the recovery of the DC systems is sped, the power imbalance and the transferred system flow caused by the concurrent commutation failures of the multi-infeed HVDC systems are relieved, and the transient stability of the system is improved significantly. The simulation results of two representative multi-infeed HVDC systems verified the effectiveness of the proposed technique.