A Single Phase Grid-Integrated PV System Using Cascaded PI and PR Controller for Power Quality Improvement

With tremendous increase in usage of renewable energy sources (RES) instead of fossil fuels, solar plays a vital role among all the renewable sources. Multilevel inverter allows the grid integration with better quality of power. In this work a two-stage single phase 5-level transformers-less PV grid-connected system is presented. To produce a 5-level output voltage, four main switches and one auxiliary switch is used in this topology. A DC-DC boost converter is created to raise the voltage level from solar PV system (SPV). P&O (perturb and observe) MPPT control algorithm is used to obtain the maximum power available. A cascaded PI and PR control strategy is utilized to control DC-link voltage and current. To control the five level inverter PD-PWM method is used in this paper. Synchronizing (SPV) with the grid voltage and current is achieved by using PLL (phase-locked loop). Performance of the system is investigated in both the dynamic and abnormal conditions (swag/swell). Results are carried out in MATLAB/SIMULINK platform with 2.1 kW grid-tied PV systems.