水电机组PID功率调节对异步送端电网的频率稳定性影响

以我国首个异步运行的省级电网——云南电网为工程背景,围绕水电机组比例-积分-微分(PID)功率调节,提出异步送端电网频率稳定性分析方法。该方法分析了定值调节和一次调频系统由于超调和外部激励导致的输出功率振荡特征,揭示了PID调节系统受初始干扰激发后所产生的超调振荡的成因、周期,明晰了外部周期性激励下调节系统持续振荡的机制及其正面或负面作用。结合云南电网的频率振荡案例验证了所提方法的有效性,并给出了防止水电机组PID功率调节引起电网频率振荡的改进策略,仿真结果表明该策略可以有效缓解水电异步送端电网的超低频振荡问题。

Impact of PID power regulation of hydroelectric unit on frequency stability for asynchronous sending-end power grid

Taking Yunnan Power Grid, the first asynchronous provincial power grid in China, as the engineering background, a frequency stability analysis approach of asynchronous sending-end power grid is proposed considering the PID(Proportion-Integration-Differentiation) power regulation of hydroelectric units. This approach analyzes oscillation characteristics of output power caused by the fixed-value adjustment and primary frequency regulation because of overshoot and external incentives. As a result, the reasons and period of oscillation motivated by initial interfere are revealed. At the same time, this approach presents the mechanism of continuous oscillation and its positive/negative effects for the regulation system under external periodic excitation. The effective of proposed method is verified by a case study regarding actual frequency oscillation of Yunnan Power Grid. Moreover, an improved strategy is proposed to avoid frequency oscillation of the power grid caused by PID regulation of hydroelectric units. Simulative results demonstrate that this strategy effectively alleviates the ultra-low frequency oscillation of hydroelectric asynchronous sending-end power grid.