多机系统超低频振荡稳定分析与调速器参数优化

Stability Analysis of Ultra-low Frequency Oscillation and Governor Parameter Optimization for Multi-machine System

云南电网与南方电网实施异步联网后出现了长时间的超低频振荡。基于奈奎斯特矢量裕度对超低频振荡的机理进行了分析。结果表明,水轮机传递函数存在右半平面零点使水电机组相位在振荡频率附近大幅滞后是引起超低频振荡的主要原因。为了避免切除调速器使跟踪性能下降,提出了一个考虑鲁棒稳定约束下最大化跟踪性能的调速器参数频域优化方法。该方法同时满足了多个方式的稳定需求,且可同时对多个机组调速器进行优化。分析与优化方法的有效性通过云南电网算例得到了验证。

A sustained ultra-low frequency oscillation occurs in Yunnan Power Grid after asynchronous interconnecting to China Southern Power Grid.The mechanism of ultra-low frequency oscillation is analyzed theoretically based on the Nyquist vector margin.The result shows that the large phase lag of hydro-power unit at the oscillation frequency,which is brought by the right half plane zero in turbine transfer function,is the key cause of ultra-low frequency oscillation.To avoid the reduction of tracking performance due to the disabling of governors,an optimization method of parameter in frequency domain for governor is proposed to maximize the tracking performance under robust stability constraints,which guarantees the stability margin in various operation points and optimizes several governors simultaneously.Case studies of Yunnan Power Grid validate the effectiveness of the analysis and optimization method.