Penetration of Wind Turbine Generator into a 50 MW Capacity Diesel Power Electric Line System

摘要

Development of a wind turbine generator (WTG) system in Japan seems to have lagged far behind compared with that in European countries and the United States. However, NEDO (New Energy and Industrial Technology Development Organization) has recently reported that Japan is also abundant in wind energy resources, based on a several-year systematic survey conducted throughout the country and that Japan could expect to obtain electricity to meet about 10-20% of national electricity demand from wind resources alone. One of the difficulties of WTG development is the fluctuation in speed and direction of natural wind, which causes fluctuations in both voltage and frequency in the electric utility system. Therefore, the problem that needs to be solved is how far WTG capacity may penetrate into that of the conventional existing electric power systems, for instance, diesel power systems on remote islands. This paper evaluates the actual performance of two 250 kW WTG pilot plants connected to a diesel power electric line system of about 50 MW located on the Miyako islands, Okinawa, Japan. Wind energy resources and wind characteristics on the islands are reported, and the fluctuation of the WTG output and its influence on the total systems are determined and also numerically analyzed. It is confirmed that the multiple WTGs have a tendency to cancel out each other's fluctuations at a rate inversely proportional to the square root of the number. From the results of the investigation and analysis, it is estimated that on the objective island WTG capacity of as much as 10 MW may be permissible, that is, 20% of the existing diesel system only if the WTG system consists of forty 250 kW machines or a much greater number of smaller-scale wind turbine generators.