柔性直流输电系统的自适应下垂反馈控制方法

提出一种柔性直流输电系统的自适应下垂反馈控制方法,通过利用柔性直流(VSC-HVDC)的灵活可控性为弱交流电网的频率和电压提供辅助支撑能力。首先,分析了柔性直流控制系统的工作原理,建立了VSC双环解耦控制的数学模型;在此基础上,提出了一种改进的双环PI解耦控制系统,分别设计了带有频率附加控制的有功功率控制器和带有电压附加控制的无功功率控制器,能够有效改善弱交流系统频率和电压的稳定性;采用了带功率偏差补偿的下垂反馈控制,改善了系统的动态响应,扩大了柔性直流的稳定运行范围。时域仿真结果验证了所提控制策略的有效性。

An adaptive power control strategy based droop feedback for VSC-HVDC

Based on the novel and controllable characteristics of VSC-HVDC, an improved double close-loop decoupling control strategy is proposed to utilize the supporting capability of VSC-HVDC for frequency and voltage of weak AC systems. A power outer-loop with AC frequency and voltage additional control functions is designed to help the fast recovery of AC frequency and voltage after disturbances. Then, an adaptive droop control with power deviation feedback is adopted to improve stable operation range of VSC-HVDC. As an example, a typical weak AC system fed by a VSC-HVDC link, including a synchronous generator with an exciter, a governor and a turbine is simulated. The time-domain simulation results demonstrate that the proposed control strategy can seamlessly handle transitions between different control modes and effectively enlarge the stability operation extent of VSC-HVDC systems.