阀门流量特性对电网稳定性影响及控制策略

Influence of Valve Flow Characteristics on Power Grid Stability and Control Strategy

在Matlab/Simulink中建立汽轮机调速系统模型和单机无穷大电网模型,分析在阀门流量特性曲线非线性区域中不同的局部流量特性系数工作时,汽轮机调节阀发生给定幅值扰动后功率曲线的变化情况。分析结果表明:当汽轮机调节阀工作在非线性区域时,机组功率曲线随局部流量特性系数变化;局部流量特性系数偏离理想流量特性系数,功率波动曲线幅值和振荡次数增加;局部流量特性系数过大或过小不利于一次调频作用下功率响应的快速稳定。针对此问题,设计并投入调节级压力控制回路,该策略能克服汽轮机调节阀开度与进汽流量之间的非线性关系,有效抑制功率波动,提高电网稳定性。

Steam turbine governing system model and single-machine infinite power grid model for steam turbine were established in Matlab/Simulink.The different local flow characteristic coefficients of the steam turbine governing valve of the valve flow characteristics curve were analyzed in the nonlinear region,a nd the change of power curve after the given amplitude disturbance were obtained in the steam turbine governing valve.The results show that when the valve is working in the nonlinear region,steam turbine generator unit power curve varies with local flow characteristics coefficient.When the local flow characteristics coefficient deviates from the ideal flow characteristics coefficient,the power fluctuation curve amplitude and the number of oscillations correspondingly increase.The larger or smaller local flow characteristics coefficient exerts a detrimental influence on the rapid stability of power response under the primary frequency control.To solve this problem,the governing stage pressure control loop was designed and added,which can overcome the nonlinear relationship between the governing valve opening degree of the steam turbine and the inlet flow,effectively suppressing power fluctuation and improving power grid stability.