适用于并网逆变器的新型LCL滤波器

针对LCL滤波器应用于并网逆变器过程中，存在谐振问题和滤波电容在5、7次谐波的作用下过流损毁的现象，首次提出了一种新型的LCL滤波器。在传统滤波支路中引入一个并联谐振和一个串联谐振，并联谐振实现滤波电容的保护，串联谐振实现开关频率谐波的滤除。首先推导了该方案下系统电压和滤波支路电流的传递函数，接着分析了滤波电容参数变化对滤波支路谐振点的影响，合理选取了本方案各元件的参数。最后对两种滤波结构进行仿真和实验，证明了所提方案在具有相似滤波效果的条件下，保护了滤波电容，降低了无源阻尼的损耗。

A novel LCL filter adopted in grid-connected inverter (1. Key Laboratory of Control of Power Transmission and Conversion (Shanghai Jiao Tong University), Ministry of Education, Shanghai 200240, China; 2. State Grid Urban Power Supply Company, SMEPC, Shanghai 200080, China;

LCL-filter adopted in grid-connected inverter has its resonant issue meanwhile the capacitor is vulnerable under the impact of 5, 7 harmonic. To this end, a new LCL topology is proposed with two resonances introduced in its filter branch, i, e. a parallel one to get the capacitor protected and a serial one to decrease switching harmonics. The transfer function of filter branch current and grid voltage under the scheme is presented firstly, then the influence of filter capacitance perameters variation on tuning point of filter branch and the basic process of parameters selection are put forward. Comparison results considering novel LCL-filter and traditional LCL-filter are presented, which show that the novel topology can achieve almost the same damping effect as by traditional topology, meanwhile, getting the capacitor well protected and decreasing power loss caused by passive damping.