Verification Test Result in Hokuto Mega-Solar System

SUMMARY The New Energy and Industrial Technology Development Organization (NEDO) advertised for consignment research business called "Verification of Grid Stabilization with Large-scale Photovoltaic (PV) Power Generation Systems" in 2006. Two sites were selected to the verification test. They are Hokuto City in Yamanashi Prefecture and Wakkanai City in Hokkaido. Mega-solar system of about 2MW and about 5MW were constructed in Hokuto and Wakkanai, respectively. The outline of Hokuto Mega-solar system is introduced and some results are described and discussed in this paper. In the first stage, we constructed the 600kW system consisting of 24 kinds of PV modules in 2006. The system was connected to 6.6kV distributed grid through 60 conventional 10kW PCSs (power conditioners). And their PV characteristics were evaluated. In the second stage which started from 2008, we constructed about 1200kW system consisting of 4 kinds of PV modules which were selected from the first stage evaluation. At that point, the total capacity of the system becomes about 1,800kW. They are connected to 66kV extra high voltage grid together with the first stage PV system. In the second stage, in order to connect the 1200kW system to the grid, we developed three 400kW largescale PSCs (LS-PCSs) so as not to adversely affect it, too. The functions of the LS-PCSs are voltage fluctuation suppression due to solar generation fluctuations, harmonics current suppression and fault ride-through (FRT) in the grid faults. The confirmation tests of the LS-PCSs were carried out using a miniature model before put into verification test in the field. The test results in a factory provided expected results and were satisfactory. Verification test results in the field are provided, too and are discussed in the paper. Verification tests of NEDO were finished in the last fiscal year. Although we transferred the system in the Hokuto city, we will continue to collect field data in cooperation with the city and to evaluate for the future.