Two-stage electrical array reconfiguration controller for PV-powered water pump

Abstract

This paper presents a technique to improve the performance of photovoltaic—powered (PV) water pumps. The method uses a solid state, two-stage electrical array reconfiguration controller (EARC), which senses the radiation as high or low. The limit of each stage can be changed. Accordingly, the controller chooses one favorable set of V- I characteristics for starting and another favorable set of V- I characteristics for steady-state operation. This is done by switching the solar panels, depending upon the starting current requirements and the insolation level, from a predominantly parallel connection to a predominantly series connection. The switching occurs at the end of the start-up of the motor. This produces a sufficient starting torque which considerably improves the pump's performance, particularly in the early morning, late evening, and on cloudy days, providing valuable extra pumping hours for the user. The performance of a direct coupled system, and a system equipped with a two-stage EARC, is presented and compared.