Verification of Grid Stabilization with Large-scale PV Power Generation Systems

In the process of rapid expansion of the photovoltaic generation system (PV system), the introduction of large-scale PV system is expected. When this PV system is interconnected to the power grid in large numbers, the electric power system, including voltage and frequency, can be significantly affected by unstable output of PV system, and the introduction of the system can be limited. This type of interconnection will require a system with no adverse impact on electric power qualities such as voltage fluctuation, frequency variations, and waveform distortion, as well as an output control system to achieve scheduled operation for reducing the peak demand of power system using large-scale PV system. In order to construct these systems and examine their availability and feasibility, New Energy and Industrial Technology Development Organization invited a new research project for this experimental study (5-year project from FY 2006), and the project jointly proposed by the city of Wakkanai and our group was successfully adopted.

In consideration of the interconnection of the MW-class large-scale PV system with various types of PV modules to the system in large numbers, a large-scale PV power plant with battery storage system (out-year project: PV-about 5,000kW, NaS battery - about 1,500kW, electrical double layer capacitor - about 1,500kW) is constructed in Wakkanai-city. Specifically, "the system with no adverse impact on electric power quality for the system such as voltage fluctuation, frequency variations and waveform distortion" and "the output control system that can achieve scheduled operation aimed at reducing the peak demand of power system using large-scale PV power generation system" will be constructed to examine their availability and feasibility.

To construct the PV system, as FY 2006 1st-period construction, the data that were measured by PV (80kW) (operation started on March 15th, 2007) and meteorological equipment (actinometer, sunshine recorder, thermometer/hygrometer, anemoscope/anemometer, etc.) were compiled. In the FY 2007 2nd-period construction, the installation of PV (2,000kW, total output) and NAS battery system (500kW) was completed and this system was interconnected to the 33kV power grid. Then, an experimental study started in the introduced output management/measurement system.

In the meantime, in the development of system stabilization technology as high-priority research, using the data obtained in the PV system installed in the 1st and 2nd period constructions, several control algorithms were simulated according to the setting conditions to find out the most appropriate operational pattern. Also, the data obtained by meteorological equipment will be utilized for the study on output prediction system toward developing output control technology.