三相光伏并网逆变器控制策略

摘要

在三相光伏并网逆变应用中,如何改善并网电流质量是备受关注的问题。采用LCL滤波器并网虽然提高了滤波效果,减小了滤波器体积,但是控制变得复杂。结合现有控制方法,本文提出了在dq同步旋转坐标系下带有电网电压前馈的比例积分（PI）级联比例谐振（PR）控制思路。建立了dq系下的三相逆变器模型,进行了控制器的分析推导,采用电压前馈改善了并网接入时的动态特性,通过PI实现了并网电流的无静差跟踪控制,级联PR实现了对特定谐波分量的有效抑制。最后,进行了仿真及在实际100kW光伏阵列下的并网逆变测试,实验结果表明该控制方案可以实现并网电流的平滑起动,能有效地降低并网电流的谐波含量。%In the application of three phase photovoltaic gird-connected inverters,how to meliorate quality of grid current is an key issue concerned.Adopting LCL filter to connect inverters with grid brings about a good filtering effect,but it makes control complex.Considering existing control method,in this paper,a strategy that cascaded proportion integrity（PI）and proportion resonation（PR）with grid voltage feed forward based on dq synchronous rotate frame is proposed.The model of three phase inverter is founded and controller was analyzed and derived.This strategy meliorated the dynamic characteristics of connecting grid by feed forward,achieved zero error tracking using PI,and suppressed harmonics currents effectively via PR.Last,simulation and experiment on a 100kW PV array grid-connected inverter are done.The results show that this proposed strategy achieves smooth grid current starting and fewer harmonics current.