A hybrid system composed of a wind power and a photovoltaic system at NTT Kume-jima radio relay station

This paper describes a 250 kW hybrid system composed of two systems which uses clean energy sources, a wind power system and a photovoltaic (PV) system. The hybrid system has been installed in the radio relay station by NTT in Kume-jima (a small island in the south-west of Japan). The hybrid system consists of a 230 kW wind turbine, a 50 kW resistor, a 230 kW bi-directional converter with storage batteries, 20 kW PV modules, and a 20 kW interactive inverter. The power generated in this system is supplied to telecommunications equipment at the radio relay station and to the power grid by reversing power flow. One of the advantages of this system is that it suppresses rapid change in the output power of the wind power system. This rapid change causes the grid voltage and the grid frequency to fluctuate because the grid capacity in Kume-jima is low.