负荷主动响应应对特高压受端电网直流闭锁故障的探讨

特高压直流输电线路因其输电容量巨大,一旦发生闭锁故障,受端电网输入功率严重缺失,将给电网运行带来巨大冲击,目前的常规调度手段可能会切除大量负荷。频率响应负荷能够在频率偏低时快速主动减少用电或退出用电;电压响应负荷可通过母线电压的主动调整来改变负荷有功大小,帮助电网快速实现功率平衡。通过对频率响应负荷和电压响应负荷调节能力的事前评估和事中统计,并与拉限电策略的在线协调优化,可以减少事故情况下的负荷切除量。发电资源和负荷资源的统一调度可提高特高压直流故障后受端电网的频率稳定水平,仿真结果表明了发电和负荷协同调度策略的有效性。

Discussion on Active Load Response at Receiving End Power Grid for Mitigating UHVDC Blocking Fault

Because of the bulk transmission capacity of ultra-high voltage direct current(UHVDC), there will be a serious power unbalance in the receiving-end power grid once the blocking fault takes place. On occasion, normal dispatch schemes, such as increasing generation output and shedding load, are not sufficient for secure operation of the power system. If the frequency is lower than the threshold, fast demand response(DR)can switch the devices or adjust the setpoint to maintain frequency stability. Meanwhile, by appropriately lowering the bus voltage, power consumption of conserved voltage reduction(CVR)can be adjusted down according to electrical devices'' static PV characteristic. So, fast DR and CVR are both able to contribute to low frequency disturbances. By referring to prior assessment and post statistics of fast DR and CVR, and cooperation between fast DR, CVR and direct load control(DLC), load shedding can be reduced during fault. Thus, the frequency stability of receiving-end power grid can be greatly enhanced by coordination between generation and demand side resources. The effectiveness of the control strategies is proved by simulation. This work is supported by State Grid Corporation of China.