Determination of Solar Hosting Capacity: A Case Study in 33 kV Distribution Network of Province No. 1, Nepal

Abstract

The case of utilities supplying energy to the consumers from centralized grid is shifting owards decentralized generation where, power production is supplemented by local distributed generations. With increase in attraction towards clean energy, such generations are usually renewable energy sources. However, integrating renewable energy sources to the power system often become troublesome due to unpredictable output of such sources. It is essential to study the capability of the grid to withstand the variations of these source before interconnecting them to the power system. Integration of large amount of renewable energy is restricted by the system reserve margin and operational characteristics of the system. The availability of Solar Insolation all around he year makes Nepal suitable location for installation of Solar Photo Voltaic (PV) Plant. This study is focused to determine the PV hosting capacity in power system network of Province No. 1, Nepal which is dominated by 33 kV lines. Steady state load low has been carried out with step increment in size of PV installed at two buses namely Inaruwa and Duhabi at 33 kV. Time domain load flow of wet and dry season, signifying excess and scarce generation in the power system has been performed. Typical data of March is used for System parameters for dry season and of June for Wet Season. Voltages at different weak buses improved after the integration of PV into the system during wet and dry season. System loss increased after injection of PV beyond 30MWp.The line loading limit and system reserve margin were not violated for this size. The financial analysis of the Grid tied Photo voltaic plant was carried out with power purchase rate of NPR 7.30 per kilowatt- hour which gave internal rate of return of 8.46%. To assess the effect of change in major variables upon the IRR of the project, sensitivity analysis was performed by varying the investment, power purchase rate and energy generation. The maximum value of IRR was found to be 11.50%, when the capital investment was set to 0.85 times of actual value as well as minimum value of IRR was found to be 5.63% when the energy generation was 0.85 times of actual value.