基于输出电流控制的光伏并网逆变电源

Research on Grid-Connected Photovoltaic Inverter Based on Output Current Control

光伏逆变电源并网运行时本质上为电流源。其输出电流滤波不但会对电网产生严重的谐波污染,同时其输出电流锁相不精确会降低系统的转化效率。针对以上问题,采用电流瞬时值和电流有效值双闭环控制策略实现对输出电流波形的控制;研制一种具有尖峰抑制作用的LCL滤波器,通过对其数学模型的幅频分析说明了其良好的滤波特性;设计了一种软件锁相环,并在此基础上通过α角的修正实现了精确可靠地锁相。实验结果验证了设计的合理性和正确性,实现了单位功率因数输出正弦波电流。

The photovoltaic inverter is a current-source in essence when it works in gridconnected mode. Its output current will produce serious harmonic pollution, and if without using a precise PLL, its transformation efficiency will be decreased. To solve the problems, a dual-loop control strategy is used based on instantaneous-current and current RMS to realize the control of the current waveform in this paper. A peak restrained LCL filter is designed. By analyzing the amplitude frequency characteristic, the LCL filter has its good filter performance; also a kind of software phase-locked is developed, and through tr amendment it can realige high accuracy and reliability. The experimental results show the rationality and correctness of the design, and can achieve the output sinusoidal current at unity power factor.