考虑变频器特性的变速恒频双馈风力发电机组控制策略的研究与仿真

以并网型变速恒频风电机组中双馈发电机的运行特性及连接于发电机转子部分的脉宽调制(PWM)控制的电压源型交-直-交变频器的结构和机理为基础,在假设变频器采用理想开关器件,即忽略电子器件的换相重叠、损耗,并只考虑变频器直流电容充放电的动态过程而不计频率调节的动态变化过程的前提下,提出了基于定子磁场旋转坐标系统下的变速恒频风电机组电气控制部分的控制策略并设计了相应的H控制器.同时基于MATLAB软件建立了变速恒频双馈风力发电机组的仿真模型,并以渐变风和随机风模式为例,针对提出的控制策略对变速恒频双馈风力发电机组的并网运行特性进行了仿真研究,仿真结果表明了该控制策略的合理性及控制器设计的有效性,同时也说明了双馈发电机在保证有功输出的情况下能够有效地调节无功功率,保证变速恒频风电机组的稳定运行.

STUDY AND DYNAMIC SIMULATION OF CONTROL STRATEGY FOR VARIABLE SPEED WIND TURBINE WITH DOUBLY-FED GENERATOR CONSIDERING FREQUENCY CONVERTER CHARACTERISTICS

On the basis of the running characteristics of doubly-fed generator in variable speed wind turbine (VSWT) and the structure and mechanism of back-to-back voltage-fed frequency converter controlled by pulse width modulation (PWM) connected to the rotor of the generator and assuming that the ideal thyristors are used to frequency converter, i.e., neglecting the commutation overlap and power loss of the electronic devices, only considering the dynamic charging and discharging process of DC capacitor in frequency converter and not taking the dynamic variation of frequency adjustment into account, the control strategy for electrical control parts of VSWT based on rotating coordinate system of stator magnetic field is proposed and the corresponding PI controller is presented. Using MATLAB the simulation model of VSWT is built, and taking the modes of ramp changing wind and random changing wind for example, the simulation of the interconnected operating characteristics of VSWT under the proposed control strategy is conducted. Simulation results show that the proposed control strategy is reasonable and the designed controller is effective, meanwhile, it is indicated that ensuring the active power output of doubly-fed generator, the doubly-fed generator can effectively regulate the reactive power to ensure the stable operation of VSWT.