OPERATIONAL EXPERIENCE AND FIELD TESTS ON ISLANDING EVENTS CAUSED BY LARGE PHOTOVOLTAIC PLANTS

This paper presents the experience on problems of islanding behaviour detected in medium and high voltage networks of Iberdrola, gathered after the breakthrough of large photovoltaic plants in Spain. Islanding field tests carried out by Iberdrola in PV plants, whose records give the clues to understand the technical reasons for the abovementioned failures, are also described. The conclusions are focused on the solutions for these problems, including improvements for protection systems, either relays or algorithm included in the inverters, new normative tests to be developed and the use of communication systems.