基于电网电压正余弦变换的三相变流器控制策略

Control Strategy for Three-phase Grid-connected Converter Based on Sine and Cosine Transform of Grid Voltage

d-q同步旋转坐标系可将三相并网变流器中的交流量映射为直流量,此时,采用经典PI调节器便可实现对交流量的跟踪。但是,dq变换所采用的电网电压矢量角通常情况下需要锁相环提供,增加了控制系统复杂性。首先,由电网电压在两相静止坐标系下的分量导出电压矢量角的正余弦值,进而提出基于电网电压正余弦变换的三相并网变流器控制策略。该算法仅以电网电压瞬时值为输入变量,大大简化了控制系统的复杂性。最后,搭建了系统仿真模型,仿真结果证明了理论分析的正确性和所提控制策略的有效性。

The AC signal in the three-phase grid-connected converter system can be mapped to DC signal by the d-q synchronous rotating coordinate system. Therefore,the classic PI controller can be used for tracking the AC signal. However,the angle of the grid-voltage vector used for dq transformation is usually provided by the phase-locked loop (PLL),and this will increase the complexity of the control system. Firstly,the sine and cosine values of the voltage vector angle were derived from the grid voltage components in the two- phase static coordinate system,and then the control strategy for three- phase grid- connected converter based on sine and cosine transform of grid voltage was proposed. The momentary values of the grid voltage was only as the input variables of the proposed method,which reduced the complexity of the control system greatly. Finally,the simulation model of the system was built,and the simulation results confirm the validity of the analysis and the proposed strategy.