基于广义积分器二自由度PID控制的LCL逆变器

Generalized Integrator Based Two Degrees of Freedom PID Control for LCL Filter-Based Grid Connected Inverter

传统有源阻尼控制可抑制LCL逆变器谐振,但需要增加额外的电压或电流传感器。为此,提出了一种无需额外传感器的基于广义积分器的LCL并网逆变器单电流反馈二自由度PID控制(GI-2DoF-PID),GI-2DoF-PID比例积分环节实现并网电流无静差跟踪,而基于广义积分器的微分环节则增强LCL逆变器的阻尼特性。推导了控制系统的传递函数,分析了其稳定裕度与动态特性,提出跟踪和抗扰动优化的参数设计原则并选取了合适的控制参数。最后,构建了基于PLECS系统仿真模型,仿真结果表明:基于GI-2DoF-PID控制的LCL并网逆变器可以有效抑制谐振;电网电压严重畸变时,其满载并网电流畸变率仅为3%,远低于国家标准的要求;当系统从半载跳变到满载时,系统超调量低,响应速度快。

Traditional active damping control can suppress the resonance of LCL inverter,but it needs to add additional voltage or current sensors.A sensorless generalized integrator based two degrees of freedom proportional integral derivative(GI-2DoF-PID)control strategy for LCL-type grid-connected inverter with single current feedback is proposed.The proportional and integral(PI)control in the GI-2DoF-PID is used to track the grid current without static error,while the generalized integrator enhances the damping characteristic of the LCL inverter.Based on the derived transfer function of the GI-2DoF-PID controller,the system stability margin and dynamic response charac-teristics are analyzed,and the controller parameters are selected according to the proposed parameter guideline for tracking and anti-dis-turbance optimization.Finally,the simulation model in PLECS is built,and the simulation results validate the effectiveness of resonance suppression in LCL-type grid-connected inverter with the proposed GI-2DoF-PID controller.Meanwhile,the total harmonic distortion(THD)of the full load grid-connected current is only 3%under seriously distorted grid voltage conditions,which is far below the national standard.When there is a step change from half load to full load,the system overshoot is low,demonstrating a fast dynamic response.