Simulation of VSI FED Grid-Connected System using Decoupled Active and Reactive Power Control

This report presents a small scale three-phase grid connected photovoltaic system with active and reactive power control scheme for improvement in voltage stability. The proposed system consists of a 100 kW PV panel with a DC-DC boost converter with controller for Maximum Power Point Tracking using perturb and observe algorithm and DC-AC 3-phase voltage source inverter with decoupled reactive power controller supplying the load. The VSI (voltage source inverter) is synchronized with the grid using a phase locked loop. A special Perturb and Observe algorithm has been developed and applied to the boost converter, in such a way that a controlled active power is produced by it. The VSI controller is used for independent control over reactive power injected by the voltage source inverter into the system, and maintains constant DC point of coupling voltage. This method improves the system stability by producing or absorbing reactive power at sudden voltage increase or decrease due to change in loads, instantaneously. The simulation of the proposed model is carried out to show its effectiveness and robustness in enhancing the capabilities of grid-connected photovoltaic systems.