Rule curves for operating single- and multi-reservoir hydropower plants

Ak, Mümtaz
Hydropower has the largest share in the energy budget of Turkey among renewable energy sources. Thus, planning and operation of hydropower plants (HPPs) are critical for the country. Currently, sustainable use and development of water resources to maximize possible benefits are the two big challenges to be overcome and efficient use of hydropower forms a significant component of this. The Çoruh Basin has an economically high hydropower potential, as such there are many HPPs that are in operation, under construction and in planning phase in this basin. Arkun, Yusufeli and Artvin are three of those HPPs located consecutively on the Çoruh River. In the first part of this study, a single reservoir system (Yusufeli HPP) with the single purpose of energy generation is considered under two separate objectives, which are the maximization of average annual energy generation and the maximization of average annual revenue, and rule curves are derived to obtain optimum reservoir operation. The results show that hourly price variations in the market should be taken into account for the maximization of the energy revenue objective and the corresponding optimal rule curves should be derived accordingly. In the second part of the study, the multi-reservoir system composed of Arkun, Yusufeli and Artvin HPPs is investigated separately considering the single purpose of energy generation under three objectives, maximization of energy, revenue and net profit. Finally, performance of the multi-reservoir system under additional purposes such as supply of municipal and irrigation water, and flood control is evaluated through hypothetical scenarios. The multi-reservoir case is operated as a pumped-storage system as well and the amount of increase in the net revenue is explored. These studies demonstrate that through integrated management of the reservoirs higher net profit with smaller installed capacity can be obtained compared to decentralized management. This reveals that integrated management of a hydropower system is very important especially for the determination of installed capacities. It is concluded that effective utilization of water resources can be achieved using optimum rule curves derived for the correct objectives.