特高压直流送端孤岛系统频率稳定控制

Frequency stability control for islanded UHVDC sending end system

特高压直流与大型水电机组配套电源采用送端孤岛运行方式,能有效消除由直流闭锁引起的潮流大范围转移、系统暂态功角失稳问题。但是,送端孤岛系统的频率稳定性是决定系统能否运行的关键因素之一。结合南方电网楚穗、普侨特高压直流孤岛的调试情况,研究了水电站与特高压直流送端孤岛系统超低频振荡的机理,提出了频率稳定控制策略;阐述了直流甩负荷导致部分机组调相运行的机理。机网协调控制RTDS试验平台的仿真结果以及特高压直流孤岛系统的现场调试结果表明了所提控制策略的有效性。

The islanded operation mode at sending terminal of UHVDC（ Ultra High Voltage Direct Current）combined with large hydroelectric generators can effectively solve the problems of large power flow reverse and transient angle instability caused by HVDC blocking. However,the frequency stability of the sending end islanded system is one of the key factors to determine whether the system can operate. Considering the debugging situations of the islanded Chusui and Puqiao UHVDC systems in China Southern Power Grid,the mechanism of ultra-low frequency oscillation of the hydropower station and islanded UHVDC sending end system is studied and a frequency stability control strategy is proposed. The mechanism of some generators in condenser operation mode after HVDC load shedding is expounded. Simulative results of unit-grid coordinated control based on RTDS simulation platform and the field test results of islanded UHVDC system verify the effectiveness of the proposed control strategy.