DYNAMIC PERFORMANCE OF A DIRECTLY COUPLED PV PUMPING SYSTEM

Although directly coupled Photovoltaic (PV) pumping systems have been extensively studied under steady state conditions, much less attention has been paid to the study of their transient performance. Actually the system is performing dynamically all the time because the solar irradiance is varying continuously. Thus, the steady state solution for the system performance is only an approximation. In this work both dynamic and steady state models are developed for a directly coupled PV pumping system. The results obtained by a detailed computer simulation program based on the two models are compared. The system is studied under external interruptions caused by sudden appearance or disappearance of clouds. The study showed that there are overshoots of both current and voltage of the DC motor. However, the characteristics of the PV array limit the overshoots during the transient period. The motor speed creeps steadily towards its steady state value without overshoot.