基于模块化多电平换流器的多端高压直流输电(modular multilevel converter based multi-terminal DC,MMC-MTDC)系统中虚拟同步发电机(virtual synchronous generator,VSG)控制在维持交流电网的频率稳定时,无法兼顾直流电压波动调节的问题.针对MMC-MTDC系统中的受端换流器,将U2-P直流电压下垂控制引入VSG控制器中,得到附加直流电压的VSG控制,该控制既能实现交流区域频率调节,又可以控制直流电压.通过分析VSG中转动惯量大小对交流电网频率响应的影响,在附加直流电压VSG控制基础上,设计一种基于模糊控制的自适应虚拟转动惯量调节方法,通过灵活调整虚拟惯量使换流器在支撑频率波动过程中表现出更平滑、迅速的动态响应性能.在MATLAB/Simulink仿真平台,对所提策略有效性进行验证,表明所提策略可以同时调节频率与直流电压,并能表现出更佳的频率动态响应性能.
Coordination Control for Multi-terminal High Voltage DC System Based on Adaptive Virtual Synchronous Generator
In the modular multilevel converter based multi-terminal DC(MMC-MTDC)system,the virtual synchronous generator(VSG)control cannot take into account the problem of DC voltage fluctuation regulation when maintaining the frequency stability of the AC grid.The U2-P DC voltage droop control was introduced into the VSG controller for the receiving-end converter in the MMC-MTDC system,and the VSG control with additional DC voltage was obtained.This control can not only realize the frequency adjustment in the AC region,but also control the DC voltage.By analyzing the influence of moment of inertia in VSG on the frequency response of AC grid,an adaptive virtual moment of inertia adjustment method based on fuzzy control was designed on the basis of additional DC voltage VSG control.By flexibly adjusting the virtual inertia,the converter shows smoother and faster dynamic response performance in the process of supporting frequency fluctuation.The effectiveness of the proposed strategy is verified on the MATLAB/Simulink simulation platform,which shows that the proposed strategy can adjust the frequency and DC voltage at the same time and can show better frequency dynamic response performance.
万方数据
维普
