配网直流变压器双极短路故障穿越方法

采用传统输入串联输出并联(ISOP)拓扑的配网直流变压器在系统发生双极短路故障时,如果不采取故障限流措施,模块电容会快速放电,故障清除后必须经过缓启充电等复杂时序完成恢复重启,无法实现故障穿越。文中提出一种基于改进型ISOP拓扑,利用故障电流阻断及限流控制实现系统故障穿越的方法。首先,理论分析了基于改进型ISOP拓扑结构的配网直流变压器系统中压侧故障穿越过程的3个阶段及其数学模型。然后,分析了基于故障限流原理的低压侧故障穿越方法及故障穿越时间的设计原则。最后,通过搭建实时数字仿真(RTDS)硬件在环半实物仿真平台进行了验证,仿真结果证明了该双极短路故障穿越方法的可行性和有效性。

Bipolar short-circuit fault ride-through method of DC transformer

When the DC transformer based on the traditional input series output parallel (ISOP) topology has a bipolar short-circuit fault, the module capacitors will discharge quickly if no fault current limiting measures are taken. After the fault is cleared, it must be recovered by complicated timing such as slow start charging failed to Fault Ride-through. A method based on improved ISOP topology, using fault current blocking and current limiting control to realize system bipolar short-circuit fault Ride-through is proposed. Firstly, the three stages and their mathematical models of the DC-voltage electronic transformer based on the improved ISOP topology are analyzed. Then, the low-voltage side fault Ride-through method based on fault current limiting principle and the design principle of fault Ride-through time are analyzed. Finally, the RTDS is built on the hardware-in-the-loop simulation platform. The results demonstrate the feasibility and effectiveness of the proposed fault traversal method.