变速恒频风力发电机组输出特性分析

The output characteristic analysis of variable-speed constant-frequency wind generating set

以变速恒频风力发电系统为研究对象,依据发电机数学模型和交流电机矢量变换控制原理,设计了交流励磁变速恒频(VSCF)发电机定子磁链定向的矢量变换控制系统,对转子侧变换器建立了外环定功率控制内环定电流控制的双闭环控制结构,实现双馈发电机定子有功P和无功Q的解耦控制,从而获得最大风能捕获的高效发电运行。并在PSCAD/EMTDC仿真环境下建立了变速恒频风力发电机组的整体动态数学模型。以渐变风和阵风为例,对由5台单机容量为2 MVA双馈感应电机(DFIG)组成的风电场并网前后的运行特性进行仿真研究,通过仿真分析,揭示了风电场并网运行的动态特性,并验证了数学模型和控制策略的正确性和有效性。

The system of variable speed constant frequency （VSCF） wind power generation is taken as study object in this paper. According to the generator mathematical models and the control principle of vector-oriented, the control system of AC excitation VSCF generator is designed based on stator flux orientation. The rotor converter adopts double locked loops control structure, Namely, the external-loop is controlled by constant power and the inner-loop is controlled by constant current, which implement the decoupling control of active power P and reactive power Q to the stator. Consequently, the maximal energy capture is obtained to operate with high-active power generation. Moreover, a whole dynamic model of double fed induction generator （DFIG） is presented using PSCAD/EMTDC, Then the ramp change of wind speed and gust are taken for example. The operation characteristic of wind farm interconnected network, which is composed by five DFIG with 2 MVA capacity, is simulated, The interconnecting dynamic performance of wind farm is validated by simulation experiment. The results also show the mathematic model and control strategy is exact and effective.