低压分布式光伏并网逆变器漏电流阻容性分量分析与提取研究

Analysis and extraction of resistive-capacitive components of leakage current in low-voltage grid-connected photovoltaic inverter

由于具备造价低、结构简单及工作效率高等特点,非隔离型并网逆变器在光伏并网系统中得到广泛应用。但因其不设隔离变压器,容易在交流电网、逆变器以及寄生电容的回路中产生共模漏电流,使电流谐波增加,产生安全隐患。因此,文章针对共模漏电流的问题,首先对逆变电路的稳态工作模式进行理论分析,得到漏电流的容性和阻性特征。其次,在理论分析的基础上提出一种基于不同特性谐波提取的漏电流分析方法,实现对漏电流的有效检测及分析。最后,通过仿真分析验证文章所提方法的有效性。

Due to the characteristics of low cost,simple structure and high work efficiency,non-isolated grid-connected inverters are widely used in photovoltaic grid-connected systems.However,because it does not have an isolation transformer,it is easy to generate common-mode leakage current in the AC power grid,inverter and parasitic capacitor loops,which increases the current harmonics and causes potential safety hazards.Therefore,aiming at the problem of common-mode leakage current,this paper first analyzes the steady-state working mode of the inverter circuit to obtain the capacitive and resistive characteristics of the leakage current.On the basis of theoretical analysis,a leakage current analysis method based on harmonic extraction with different characteristics is proposed to realize the effective detection and analysis of leakage current.Finally,the effectiveness of the proposed method is verified by simulation analysis.