10 MW中压六相直驱永磁风电机组最大功率跟踪策略研究

Study on Maximum Power Tracking Strategy of 10 MW Medium Voltage Six-Phase Direct-Drive Permanent Magnet Wind Turbine

为了提高大功率海上风力发电机组并网的安全性及稳定性,在采用中压六相永磁同步发电机搭配分布式中点箝位变流器构成10 MW风力发电系统的基础上,提出一种适用于中压六相永磁发电机组的最大功率跟踪策略。根据风电机组转速反馈值计算电机转矩最优参考值,并通过前馈解耦的方法设计永磁发电机定子的双d-q电流控制环,从而由转矩与双dq电流环的闭环组合完成六相永磁发电机组的最大功率输出控制;同时,为了平抑中点箝位型变流器直流侧中点电位波动,提出一种调制系数与矢量组选择协调调控的中点电位平衡方法,通过调节调制系数大小来平抑中点电位波动,在调制系数越限情况下,利用协调矢量组选择方式控制中点电位平衡;最后,在MATLAB中建立10 MW永磁风力发电系统模型,验证了所提控制策略的有效性。

In order to maximize the grid-connected power of high-power offshore wind turbines,a maximum power tracking strategy suitable for medium voltage six-phase permanent magnet synchronous generator(MVSPMSG)was proposed in the paper based on the use of MVSPMSG and distributed neutral point clamped converters to form a 10 MW wind power generation system.The optimal reference value of torque was given according to the speed feedback value,and the dual dq current control loop of the permanent magnet synchronous generator(PMSG)stator winding was designed through the feedforward decoupling method.The maximum power output control of the MVSPMSG was completed by the closed-loop combination of torque and double dq current loop.At the same time,a midpoint potential balance method with modulation coefficient and vector group selection coordinated adjustment was proposed to suppress the neutral point potential fluctuations on the DC side of the neutral point clamped converter.The method of adjusting the magnitude of modulation coefficient to suppress the fluctuation of the neutral point potential was first adopted.Meanwhile,the coordination vector group selection was applied to control the neutral point potential balance when the modulation factor exceeds the limit.Finally,a 10 MW permanent magnet wind power generation system model was established in MATLAB to verify the effectiveness of the control strategy proposed in the paper.