陈国定，钟引帆，揭　飞

(浙江工业大学 信息工程学院，浙江 杭州 310023)

非隔离光伏并网逆变器共模电流抑制研究

陈国定，钟引帆，揭飞

(浙江工业大学 信息工程学院，浙江 杭州 310023)

摘要：共模电流问题是非隔离光伏并网系统需要解决的关键问题之一.VDE-0126-1-1标准规定，当漏电流超过规定值时，并网系统必须在规定时间内停止工作.针对共模电流问题，分析其产生的原因，研究和对比了了几种不同的调制方式，并详细分析了几种能够有效抑制或消除共模电流的电路拓扑结构，得到了不同拓扑结构之间抑制共模电流的共同特征.在此基础上，根据oHeric拓扑结构，提出了其相应的调制策略并分析和阐述了其工作原理.最后通过仿真验证了oHeric拓扑抑制共模电流的有效性.

关键词：非隔离；共模电流；oHeric拓扑；调制策略

Research on common mode current suppression of transformerless

inverter in non-isolated photovoltaic grid system

CHEN Guoding, ZHONG Yinfan, JIE Fei

(College of Information Engineering, Zhejiang University of Technology, Hangzhou 310023, China)

Abstract:Common mode current suppression is one of the key points for non-isolated photovoltaic grid system. In VDE-0126-1-1 specification, the photovoltaic systems should be disconnected from the grid within the stipulation time in case the leakage current exceeds specified value. In view of the problem of leakage current, the reason was analyzed firstly, researching and comparing different kinds of the modulation, some topologies which can restrain common mode current effectively were analyzed in details, and obtained the common feature about the different topologies. Based on the common feature, put forward the modulation strategy about oHeric topology, and analyze and elaborate the working principle. Finally, the simulation results show that the oHeric topology can effectively suppress common mode currents.

Key words:non-isolated; common mode current; oHeric topology; modulation strategy

近年来，光伏发电系统在世界范围内得到广泛的应用.作为光伏系统的并网接口，逆变器起着重要作用，尤其是低功耗、高效率、小体积、低成本的并网逆变器[1-3].并网逆变器按照是否具有变压器以及变压器的类型分为工频隔离型、高频隔离型以及非隔离型逆变器.含变压器的隔离型逆变器，确保了电网和光伏系统之间的电气隔离和电压匹配，这样既保护了人身和设备的安全，又抑制了并网电流的直流分量保证系统的稳定运行.然而，工频变压器存在体积庞大、重量重、价格高等问题；而高频隔离型逆变器的控制策略和拓扑结构都相对复杂，元……