LCL滤波的三相并网逆变器电流双环控制策略

对于LCL滤波的三相并网型逆变器系统,电网电压畸变会增加网侧电流总谐波。针对该问题,分析了传统逆变侧电流单环控制策略无法有效抑制电网电压畸变对网侧电流的影响。为了增加网侧电流对电网电压畸变的抗扰性,提出了电流双环的控制策略。内环通过PI控制器实现对逆变侧电流的控制,外环通过PI+PR的控制方案完成对网侧电流的控制。通过推导系统的输出导纳的频率响应,分析了在提出方案下,网侧电流能够更有效地抑制网侧电压畸变的影响。仿真以及100kW样机的实验结果验证了该控制策略的有效性。

Current Dual-loop Control Strategy for Three-phase Grid-connected VSI with LCL Filter

In grid-connected PV inverter system, grid voltage distortion would give rise to extra grid current harmonics. The shortage of inverter output current control scheme in suppressing the grid current harmonics caused by grid voltage distortion for grid-connected three-phase voltage source inverter (VSI) with LCL filter under d-q rotating frame was analyzed firstly. To damp these harmonics, a novel dual-loop control scheme was proposed, in which inverter output current inner loop is controlled by PI controller and grid current outer loop is regulated by the combination of PI and PR controller. PR controller would yield a good performance in damping special order harmonics under this control scheme. Output admittance of the system was derived to analyze the impact of grid voltage distortion on grid current. Stability and effectiveness of this proposed strategy were verified with theoretical analysis as well as simulation and experimental results under 100kW PV inverter prototype.