多功能串联补偿器虚拟阻抗柔性限流及其运行机理

Multi-functional Series Compensator Based on Virtual Impedance Flexible Current-limiting and Its Operating Mechanism

针对短路故障时冲击电流的柔性控制,提出了一种自适应虚拟阻抗柔性限流的多功能串联补偿器MFSC(multi-functional series compensator)拓扑结构及控制策略。分析其在正常运行和不同类型短路故障时的工作状况及模式切换过程,阐述三相四桥臂串联逆变器中引入虚拟阻抗的控制方法,建立短路故障数学模型,并给出虚拟阻抗和晶闸管支路限流阻抗参数设计方法。仿真及实验结果表明,MFSC能有效抑制不同类型短路故障电流,故障发生后,虚拟阻抗控制可实现电能质量补偿模式与限流模式间的平滑切换,实现故障电流与继电保护整定值相配和。

Aiming at the flexible control of inrush current under short-circuit fault, the topological structure and control strategy for a multi-functional series compensator(MFSC) based on virtual impedance flexible current-limiting are proposed. Its working modes and mode switching process under normal operation and different types of short-circuit fault are analyzed. The control method for virtual impedance which is introduced to a three-phase four-leg series inverter is analyzed, and a mathematical model of short-circuit fault is established. The design method for parameters of virtual impedance and thyristor branch current-limiting impedance is given. Simulation and experimental results showed that the proposed MFSC can effectively suppress different types of short-circuit fault current;after a fault occurs, the virtual impedance control can realize smooth switching between power quality compensation mode and current-limiting mode, as well as the coordination of fault current and the relay protection setting value.