基于Z源电容电压变化的并网电流控制策略

摘要

Z-source inverter is a single-stage system.It has some advantages such as simple structure,high reliability of the inverter for avoiding influence of the shoot-through by EMI,and small output waveform distortion.Especially,this topology applies to the occasions of large rang input voltage such as PV power generation,etc.In PV grid-connected system,the frequent change of output current will bring the negative impact on the power quality.This paper proposes the Z-source capacitor voltage-change adjustment method to control ac line current amplitude,combined with the characteristics of single-phase Z-source PV grid-connected inverter.The proposed method can improve the power quality of the grid and minimize the injected ac line current variation.The experimental results verify the validity of the proposed control strategy.%Z源逆变器属于单级系统,具有结构简单,允许逆变桥同一桥臂上下功率器件直通,输出波形畸变小等优点,在光伏发电等输入电压变换范围比较大的场合具有很好的应用前景。在光伏并网系统中,并网电流的频繁变化将会对电网的电能质量带来负面影响。为此,本文结合单相Z源光伏并网逆变器的特点,提出了通过Z源电容电压变化来调节并网电流幅值的控制方法。该方法能够减小并网电流的波动,从而改善并网电流的波形质量。实验结果证明了该控制策略的有效性。