INVESTIGATION OF THE TRANSIENT BEHAVIOUR OF A GRID-CONNECTED PHOTOVOLTAIC GENERATOR

Abstract

Installation of off-grid (stand-alone) photovoltaic (PV) generators as alternative electricity sources has been on the increase in developing countries. In Nigeria, the recent Federal Government policy of deregulating the electrical utility has brought the grid-connected PV technology into a great attention. However, possible transient consequences of using the technology are threats to its immediate adoption. This paper therefore presents a study on the transient behaviour of grid-connected photovoltaic generator. By experimenting with a simulated model of a typical grid-connected photovoltaic power system, the generator's response to faults applied at its terminals was investigated. The resulting waveforms reveal damped oscillatory behaviour of the terminal variables due to a symmetrical short circuit. Applications of non-symmetrical short-circuit also resulted to instability at the generator's terminals. Nevertheless, following the clearance of each fault, the system resumes its normal operation with the variables smoothly settled at their initial stable values. The investigation reveals that by providing protective devices and standard means of fault isolation, the possible effect of the instability on the entire system can be minimized.