A holistic techno-economic evaluation framework for sizing renewable power plant in a hydro-based hybrid generation system

Abstract

The configuration of the hybrid generation systems (HGSs) is critical for maximizing the synergy between different power sources. However, accurately simulating the operation of HGSs over their lifespan is challenging due to the need to balance multiple objectives covering different timeframes. For example, long-term water management and short-term peak-shaving can conflict. To tackle this problem, we propose a comprehensive evaluation framework that optimizes the size of a renewable power plant integrated with an existing hydropower station. This framework combines a long-term and short-term operation model with a techno-economic analysis. Unlike traditional models, our short-term operation model prioritizes power supply quality and quantity while maintaining satisfactory peak-shaving performance for the HGS. We generated numerous daily generation plans using this model to derive the multidimensional response functions, which describe the relationship between long-term hydropower decision, renewable power output and short-term performance indicators. These response functions were then incorporated into a refined long-term operation model to simulate the HGS's extended operation. Finally, we employed a holistic evaluation framework comprising various techno-economic indicators to determine the cost-effective size of the renewable power plant. We applied this framework to the Igong Zangpo River Basin in China, a tributary of the Yarlung Zangbo River. The results revealed the following: (1) Increasing the size of the photovoltaic (PV) component resulted in a decline in technical performance, including energy use efficiency and peak-shaving capabilities; (2) Given sufficient transmission capacity, a PV size threshold of 2400 MW was identified, while the optimal PV size with the highest net present value was 1950 MW, twice the capacity of the hydropower installation (1030 MW); and (3) The optimal PV size varied from 0 to 2400 MW based on electricity price and initial investment factors. Thus, our proposed techno-economic framework effectively guides the capacity configuration of the hydro-based HGSs.