VSC-HVDC系统新型广义直流电压控制策略

建立了基于电压源换流器（VSC）的高压直流（HVDC）（VSC-HVDC）输电系统的标幺值数学模型。为了抑制系统故障时直流电压的波动幅度，基于上述模型，提出了一种新型广义直流电压控制策略。在此控制策略下，换流站间不需要通信，外环有功功率控制器为一个广义直流电压控制器（GDCVC）。当直流电压因交流系统受到扰动或直流电压控制器（DCVC）故障等原因而不能有效维持直流电压时，维持和限制直流电压的功能可平滑、自动地由有功功率控制器接替，从而达到保护设备安全运行、提高系统持续运行能力的目的。仿真表明，文中提出的控制策略在稳态和暂态过程中均具有良好的控制效果，对实际VSC-HVDC系统的控制器设计具有参考意义。

A Novel Generalized DC Voltage Control Strategy for VSC-HVDC

Based on a set of properly selected base values,a per-unit model for voltage source converter (VSC) based high voltage direct current (HVDC) (VSC-HVDC) is developed.With the proposed model,a novel generalized DC voltage control strategy is proposed in order to reduce DC voltage variation caused by system fault.The system can operate without communication between converter stations under this control strategy.An active power controller (APC) of outer loop can be treated as a generalized DC voltage controller (GDCVC).When DC link voltage can not be maintained by the DC voltage controller (DCVC) for some reasons,the APC takes over the function of DCVC automatically and smoothly.So the variation of DC link voltage may be suppressed and safe operation of the VSC-HVDC system can be maintained.Therefore the capability of sustained operation can be enhanced with the help of GDCVC.Digital simulation shows the good performance of the proposed control strategy both at steady and transient conditions.