VSC-HVDC供电无源电网的频率控制策略

Frequency control of passive power grid with VSC-HVDC supply

向无源网络供电的柔性直流输电系统在送端交流电网故障下,由于限流器作用,会使受端交流电网出现功率缺额问题,进而影响受端电网的电压稳定性。通过分析有功功率不平衡量,研究影响直流电压变化的机理,获得扰动下直流电压变化与频率响应之间的映射关系,进而提出逆变站的频率控制策略;利用负荷频率特性调节,将故障信息通过频率传递给保护装置,提高了系统故障穿越能力。PSCAD/EMTDC仿真结果表明:所提出的控制策略能够有效地提高VSC-HVDC受端系统的故障穿越能力。

For the passive power grid with voltage source converter based high voltage direct current systems（VSC-HVDC）supply,if faults occurr on the sending network,the receiving network will suffer power shortage due to current limiter affecting.Furthermore,it may cause voltage collapse.The relationship between DC voltage variation and dynamic frequency response under disturbance was analyzed,and the mechanism of DC voltage variation with active power unbalance was obtained in this paper.The frequency control strategies of inverter were thus proposed.According to the active demand of the load frequency regulation characteristics,the unbalance information was transmit to the protection devices,and the fault ride-through capability of the power grid was improved.PSCAD/EMTDC simulation results showed that the proposed control scheme can improve the fault ride-through capability.