1. Department of Engineering, University of Sannio in Benevento, Piazza Roma 21, Via Traiano, 3, 82100 Benevento, BN, Italy
2. Department of Energy Technologies and Renewable Energy Sources, ENEA, 80055 Portici, NA, Italy
3. Department of Electrical Engineering and Information Technologies, University of Naples Federico II, C.so Umberto I, 40, 80138 Napoli, NA, Italy