基于扰动观测器的光伏逆变器鲁棒分数阶PID控制

Perturbation observer based robust fractional-order PID control for PV inverters

文中设计了一款基于扰动观测器的鲁棒分数阶PID控制(Perturbation Observer based Robust Fractional-order PID control,PORF-PID)来实现光伏逆变器的最大功率跟踪。将光伏逆变器的非线性、参数不确定性以及未建模动态聚合成一个扰动,并通过滑模扰动观测器(Sliding-Mode Perturbation Observer,SMPO)对其进行在线估计。随后,采用分数阶PID控制(Fractional-order PID control,FPID)对该扰动估计进行实时完全补偿,从而实现不同工况下全局一致的控制性能。由于引入了分数阶控制框架,额外的控制器参数可进一步提高闭环系统的动态响应特性。为验证所提控制器的有效性,文中进行了两种算例研究,即光照强度变化和电网电压跌落。仿真结果表明,PORFPID控制与常规PID控制、FPID控制和反馈线性化控制(Feedback Linearization Control,FLC)相比,能在各类工况下实现最快的动态响应以及最低的超调量。

This paper designs a perturbation observer based robust fractional-order PID control(PORF-PID)scheme to achieve the maximum power point tracking(MPPT)of photovoltaic(PV)inverters.Firstly,the nonlinearities,parameter uncertainties and un-modeled dynamics of PV inverter are aggregated into a perturbation,which is then estimated online by a sliding-mode perturbation observer(SMPO).In addition,the perturbation estimate is fully compensated in the real-time by a robust fractional-order PID control(FPID),so that a global control consistency could be realized in the presence of various operation conditions.Due to the utilization of fractional-order control framework,the additional controller parameters could further improve the dynamical responses of the closed-loop system.Two case studies are carried out,e.g.,solar irradiation variation and power grid voltage drop,to verify the effectiveness of the proposed approach.Simulation results demonstrate that PORF-PID control can achieve the fastest dynamical responses and the lowest overshoot in comparison to that of conventional PID control,FPID control,and feedback linearization control(FLC)under different operation conditions.