Cooperative control of photovoltaic based water pumping system

Abstract

In this study, novel control schemes are developed for cooperative control of stand-alone and grid-connected photovoltaic (PV) based water pumping system. Brushless DC motor is used as pumping motor due to its superior characteristics. The cooperative control effectively utilises the available resources. In stand-alone system, control scheme is developed for power sharing among PV pumping units. Assuming some of the PV units have battery, the charging/discharging controller is incorporated. In grid-connected system, flexible control scheme is proposed so that consumer can draw lesser power from grid by running the motor at lower speed instead of rated speed. In case of high PV power penetration into weak grid, the modified perturb and observe algorithm is proposed for sharing of de-loaded power among the PV units. Due to de-loading of PV power, motor speed reduces, hence, speed compensation mechanism is developed to bring back the speed at desired value. As a futuristic concept, consumer can buy power from neighbour instead of taking from grid. To establish above-mentioned concept, control scheme is developed for sharing the power among PV pumping units. The simulation and hardware results are carried out to test performance of the proposed control schemes.