无功调控对暂态功角稳定性的影响

Effect analysis of reactive power control on transient angle stability

单机无穷大系统和实际电网的仿真算例表明,在发电机有功出力不变的情况下,通过增加临界群发电机组的无功出力可提高电力系统的暂态功角稳定性和输电功率极限。运用等面积法则对其机理进行详细分析并得出结论:增加发电机的无功出力对系统功角稳定的影响随故障切除时间的改变而改变,当在故障后的恢复曲线高于初始机械功率时,其对功角稳定的影响效果明显,并随着故障切除时间的延迟将逐渐增大,而切除时间很短时,增加发电机无功的初始出力对系统功角稳定的影响并不大。仿真结果证明了其正确性和合理性,从而为电力系统的稳定运行提供了一种灵活的控制手段。

Simulations on a one-machine infinite- bus system and a practical electrical power network show that,with the active power output unchanged,the increase of critical generator reactive power output can improve the transient angle stability and transmission limit. The equal area criterion is applied in the detailed mechanism study and the conclusions are： the effect of generator reactive power output increase on system angle stability is changing along with the fault cutting time. When the resumed active power after fault is larger than the initial mechanical power,the effect is obvious and increases with the time delay of fault cutting. If the cutting time is very short, the effect is little. Simulation results prove its correctness and rationality,which provides a flexible control means for stable power system operation.