DETECTION OF ISLANDING OF MULTIPLE DISPERSED PHOTOVOLTAIC POWER-SYSTEMS

Protection from islanding is one of the most important R&D items for p hotovoltaic (PV) and other dispersed power systems connected to a util ity power grid and supplying back surplus power. To protect against is landing, dispersed power systems should be able to detect loss of powe r in the power grid and be disconnected from the grid immediately. How ever, a reliable method for detecting the islanding, especially when m ultiple dispersed systems are connected to one power distribution line , has not yet been developed. We have developed a new method to detect the islanding using correlation techniques. In this article the detec ting ability of the correlation method is analyzed when multiple power systems are connected to a power distribution line and compared with that of a usual voltage perturbation method. It is shown that the corr elation technique is effective for the case of multiple connection of the PV systems to line, while a usual voltage perturbation method is n ot effective. Copyright (C) 1996 Elsevier Science Ltd.