超速与变桨协调的双馈风电机组频率控制

Frequency Regulation by Doubly Fed Induction Generator Wind Turbines Based on Coordinated Overspeed Control and Pitch Control

双馈风电机组的有功功率输出无法响应电网频率的变化,并且由于其通常运行在最大功率点跟踪模式下,亦无备用的有功功率支援电网的频率控制。通过提升发电机转子转速和调节桨距角可实现双馈风电机组的减载运行,从而保留部分有功功率作为备用以提升对电网频率的调节能力,但是超速控制和变桨控制在不同工况下,具有一定的工程局限性。为深入挖掘双馈风电机组的调频潜力,提出了一种超速与变桨相协调的调频控制策略。该控制策略根据不同的风速条件,将调频分为低风速、中风速和高风速3种模式,并详细分析了可辨识这3种模式的判据。仿真结果表明,基于文中提出的控制方法,双馈风电机组可以有效提升系统的频率稳定性。

Doubly fed induction generators（DFIGs） provide little active power response to frequency changes of power grid.Meanwhile,traditional DFIGs cannot regulate their active power to support the system frequency due to the operation of maximum power point tracking（MPPT）.DFIGs can be down-regulated through increasing wind generator rotor speed or adjusting pitch angle,thereby improving frequency regulation margin for power systems.However,in various operating conditions,overspeed control and pitch control both have limitations in real engineering application.In order to utilize the potential of DFIGs frequency regulation capability,this paper presents a frequency control strategy to coordinate overspeed and pitch controls.Depending on the wind speeds,the coordination strategy is composed of low,medium and high wind speed control modes and the correlated criterion is also presented.Simulations show that the system frequency stability can be improved by DFIGs based on the proposed control methods.