非隔离光伏并网逆变技术的现状与展望

State-of-the-art and Future Trend of Transformerless Photovoltaic Grid-connected Inverters

非隔离并网系统因不含低频和高频变压器而具有变换效率高、成本低、重量轻等突出优势,近年来专家学者们对其开展了大量的研究,并在新能源开发,特别是在分布式光伏并网中普及应用。该文分析并归纳了非隔离逆变技术的发展现状。首先,从非隔离并网系统的共模分析模型出发总结出三大类漏电流抑制准则。接着,分别就第一代非隔离并网系统的两大关键技术:漏电流抑制拓扑和进网直流成分抑制方法进行分类讨论。最后,结合日益成熟的宽禁带器件对第二代非隔离并网系统的关键技术与挑战进行了展望。

Transformerless grid-connected inverter(TLI) systems feature high efficiency, low cost, low volume and weight due to using neither line-frequency transformers nor high-frequency transformers. Therefore, TLIs have been extensively investigated in academic community and commonly installed in renewable energy industry, especially for distributed photovoltaic grid-connected systems during the decade. This paper analyzed and summarized the state of the art of TLI techniques. Three rules of leakage current(LC) suppression have been concluded from a generic common-mode(CM) voltage analysis model at the beginning. Secondly, LC suppression topologies and direct current(DC) injection methods, so called as two key challenges of first generation TLIs, have been classified and discussed in detail. Finally, some challenges and future trend of next-generation TLIs have been presented based on wide bad gap devices.