多逆变器并网耦合谐振机理及有源阻尼优化方法

Coupling Resonances Mechanism of Grid-Connected Multi-Parallel Inverters and Its Active Damping Parameter Optimal Method

对采用LCL型滤波器的并网逆变系统串、并联谐振的分析往往缺乏全局观,使得对逆变系统耦合谐振现象的机理揭示不够清晰及准确,进而难以实现有源阻尼参数的优化选取。为解决这一问题,建立具有一般性特点的多逆变系统并网数学模型。该模型对两类典型并网逆变系统控制结构具备普遍适用性。利用该模型定性及定量分析了逆变系统耦合谐振现象的机理和规律。并着重分析了本征谐振点随并网逆变器数量变化在频域内的分布特点及规律。同时,结合图示法可以方便、直观地寻求有源阻尼参数对耦合谐振衰减的最优取值范围。最后,通过仿真和实验验证耦合谐振机理分析结论的正确性及有源阻尼优化方法的可行性。

Due to lack of global view, analysis of series resonance and parallel resonances for grid-connected multi-parallel inverters with LCL filter fails to illustrate coupling resonance mechanism clearly and accurately. This causes difficulty in selecting optimal control parameter. To tackle the problem, a generalized model of grid-connected parallel inverters is built. The model can be used to explain coupling resonance for two kinds of typical control structures of grid-connected inverters. With this model, series and parallel resonances are explained qualitatively and quantitatively. Features of intrinsic resonance are explicitly analyzed. The most salient of this model is to choose optimal value of active damping parameter very conveniently. Finally, simulation and experiment are conducted to investigate correctness of conclusion for coupling resonance mechanism and to verify feasibility of optimal method of active damping parameter.