双馈风电机群并网系统时变最优潮流的优化追踪方法

Method for time-varying optimal power flow tracking of doubly-fed wind turbine grid-connected system

针对风力发电功率不确定性引起的风电系统并网点及内部节点的电压协调控制在优化速度上难以追随的问题,建立了双馈风电机群并网系统时变最优潮流的优化追踪模型,并给出了模型的在线快速求解方法。在实时量测、通信技术使风电系统可观测的前提下,该模型和求解方法着眼于极短优化周期内风电系统状态量变化微小的特点,通过保留泰勒展开一阶项使模型线性化,得到时变的线性优化模型,实现模型的毫秒级求解,从而实时追求风电系统的最优潮流状态。该方法利用双馈感应发电机有功、无功功率间时变的调节范围,协调各机组的有功、无功功率输出,以挖掘双馈风电机群电力电子化技术下的快速调控潜力。对某实际双馈风电机群并网系统进行算例分析,分析结果表明该方法能够有效缓解并网点和内部节点的电压问题,实现风电系统的时变最优潮流追踪。

Aiming at the problem that the voltage coordinated control optimization speed of PCC(Point of Common Coupling)and internal nodes of wind power system is hard to catch up with the uncertainty of wind power,a model for time-varying optimal power flow tracking of doubly-fed wind turbine grid-connected system is established,and the online fast solving method of the model is proposed.Based on the real-time measurement and communication technology to make the wind power system observable,the model and solving method focus on the characteristics of minute state variables of wind power system in extremely short optimization period,linearize the model by retaining the first order term of Taylor expansion to obtain the time-varying linearized optimal model,which realize the millisecond level solution of the model,moreover pursuit the optimal power flow state of wind power system in real time.The time-varying regulation range between active and reactive power of doubly-fed induction generator is used to coordinate the output of active and reactive power of each unit,so as to dig the potential of rapid regulation and control of doublyfed induction generator under the power electronic technology.A practical calculation example of doubly-fed wind turbine grid-connected system is analyzed,the results show that the proposed method can effectively alleviate the voltage problem of PCC and internal nodes of wind power system,and realize the time-varying optimal power flow tracking of wind power system.