直流并网型双馈风力发电系统限转子功率运行控制方法

Limited rotor power control method of double-fed wind power generation system connected to DC grid

针对双馈风力发电系统并入直流微网拓扑,提出一种全风速范围都能限制转子馈送功率的控制方法以降低系统中转子换流器的成本。实现该控制方法的关键点在于,在实现最大风能追踪控制的同时,调整并入直流微网的双馈机的定子频率,在风速较高时通过矢量控制的磁链环增大定子频率,以一定的负转差将转子侧功率限制在较小的恒定功率下,风速较低时以低于工频的恒定子频率运行,使转差率在较小范围内正负变化,从而限制转子侧功率的绝对值。在定子侧不控整流、转子侧经换流器接直流微网的拓扑下,对1.5 MW双馈风力机限转子功率的控制方法进行仿真,结果表明从切入风速到额定风速的区域,均可使转子侧功率的绝对值限制在70 kW之内。

For the topology of doubly-fed wind power generation system being integrated into DC microgrid,this paper proposes a control method which limited the rotor power in the full range of wind speed,and thus reduced the cost of rotor side converters in the doubly-fed wind power generation system.The key to this control method is that the stator frequency of doubly-fed generators prior to the rectification is adjusted properly,and the maximum wind power tacking is realized in the meanwhile.When the wind speed is high,the stator frequency is increased by the vector control loop of flux,and the rotor power is limited to a small and constant value with a negative slip.When the wind speed is low,the stator frequency is kept constant at a value slightly smaller than the grid frequency,and the slip varies in a small range of positive and negative values,so that the absolute value of the rotor power is limited.Under the topology of stator-side uncontrolled rectifier and rotor-side converter connected to DC microgrid,the scheme and control method of limiting rotor power was simulated on a 1.5 MW doubly-fed wind turbine.The results show that the absolute value of rotor power can be limited to 70 kW in the maximum wind power tracking range from the cut-in wind speed to the rated wind speed.