基于空间脉宽调制控制技术的双馈风力发电机动态性能研究

Study on Dynamic Performance of Doubly-Fed Wind Turbine Based on Space Pulse Width Modulation Control

针对异步发电机功率变化波动大、暂态性能差,故障情况下无法持续供电等诸多不利因素,首先提出了双馈风机的简化数学模型,基于空间脉宽调制(space pulse width modulation,SPWM)控制技术,利用方程直接解出了定子输出功率和转子电流的数学关系;然后设计了PI控制器实现了双馈风力发电机有功功率和无功功率的解耦控制,并通过调节控制器增益,加快了风机转子侧的无功响应速度,极大地改善了双馈风力发电机接入电网的暂态性能;最后将该发电机模型放入9机微型电网系统中进行了稳态和故障2种情况下的仿真。仿真结果表明:该控该制策略合理有效,不仅能成功实现有功和无功的解耦控制,且能较大提高电网暂态性,保证了变速恒频风电机组并网后的稳定运行。

There are many adverse factors in asynchronous generators such as wide power fluctuation range, poor transient performance, unable to supply power continuously under fault condition and so on. For this reason, a simplified mathematical model of doubly-fed induction generator （DFIG） is proposed; then based on space pulse width modulation （SPWM） technique, the mathematical relation between stator output power and rotor current of DFIG is directly solved by equations; and then a PI controller is designed to implement the decoupling control of active and reactive power of DFIG and by means of adjusting the controller gain the reactive power response speed at rotor side of wind turbine is speeded up, thus the transient performance of connecting DFIG with power grid is greatly improved; finally, the proposed DFIG model is added in a 9-machine microgrid to carry out the simulation under steady state and faulty condition. Simulation results show that the proposed control strategy is reasonable and effective, not only the decoupling control of active and reactive power can be implemented, but also the transient stability of microgrid can be evidently improved, besides, the stable operation of grid-connected variable speed constant frequency （VSCF） DFIG can be ensured.