Self-tuning Adaptive Control of a Four Wire PV system as Grid-connected Inverter and Active Power Filter

Photovoltaic systems have found wide application recent years. Nonlinear nature of PV systems shows the need to design a suitable controller for desirable performance during different operating points. In this paper, a grid-connected PV system composed of boost converter plus four-leg inverter and LCL filter, is presented which in addition to power injection, it is used for power quality improvement. A digital Self-tuning indirect adaptive control strategy based on the minimum degree pole placement method is proposed for control of the PV inverter in presence of large signal changes and uncertainty of system components. Simulation results show that the proposed method is able to keep a good performance despite of dynamic changes of the converter, load disturbance and PV voltage changes and permits a wide range of input voltage from PV and also compensates the nonlinear, unbalanced and reactive load current effectively.