具有输入低频电流纹波抑制功能的光伏高频链并网逆变器

光伏发电系统对光伏电池输出电流低频纹波有严格的要求,而普通光伏并网逆变器通常增加滤波器容量或复杂的控制策略实现输入低频电流纹波抑制。将LCL-T谐振网络引入光伏并网逆变器,在变换器开关频率等于谐振频率时,可由谐振网络特性有效抑制光伏电池输出电流中的低频纹波。分析了光伏并网系统中电流、电压与各元件参数之间的关系,提出了相关元件参数的设计规则,并提出了相应的控制策略。实验结果表明,所提逆变器能够很好地抑制光伏电池输出电流中的低频纹波,且具有较高的效率。

High-frequency-link Inverter with Input Current Ripple Reduction for Photovoltaic System

The low-frequency current ripple (LFCR) in output current of photovoltaic cells has to satisfy strict requirements of the photovoltaic generation system. A commonly used method of restraining LFCR is using a bigger filter or a complicated control strategy in an ordinary photovoltaic grid-connected inverter. The LCL-T resonant network is introduced into the photovoltaic grid-connected inverter. The LFCR can be effectively suppressed with the intrinsic characteristics of the LCL-T resonant network when the switching frequency of the converter is equal to the resonant frequency. The currents and voltages of the proposed inverter are derived and design guidance for component parameters and corresponding control strategy are proposed. The experimental results have verified that the LFCR can be well suppressed and the proposed inverter has high conversion efficiency. This work is supported by National Natural Science Foundation of China (No. 51577164, No. 51107108).