Synergetic operation of photovoltaic and hydro power stations on a day-ahead energy market

Abstract

Hydropower has huge potential for a technically feasible and economically justified integration of variable, renewable energy sources with the power system. On the other hand, the operational intricacies of hydropower stations with a reservoir are limited by various constraints. Many previous works addressed the idea of solar-hydro resources complementarity, optimal sizing of such systems or their optimal dispatch. However, no one has ever established such a system in a highly competitive energy market with strongly fluctuating energy prices. Therefore, in this paper, we analyse the potential operation of a photovoltaic-hydro (PV-hydro) hybrid power station on a day-ahead electricity market. Due to its relatively small size such a station can be considered on the market as a price taker.The mathematical model which is used takes into consideration the irradiation and inflow uncertainty. A bidding strategy is created; based on the forecasted availability of solar and hydro energy during the day. The electricity prices on the market are taken from historical data and the optimized bidding strategy which is the repeatable for each day of the year. The operation of solar and hydropower stations on the day-ahead market as independent power stations is used as a benchmark for the hybrid system.The results of our analysis are promising and indicate a 5% increase of revenue for a joint operation (comparing to independent operations) providing the energy price increases by 3% per year. The hybrid system not only provides a greater profit to the owner, but also improves the small water retention during the hot period in summer. Over the whole year, the average monthly reservoir state of filling is greater than 73%. In the joint operation mode, the capacity factors of both sources are kept on a relatively high level of no less than 95% of their initial values based on resources availability.