Study on short-term optimal operation of cascade hydro-photovoltaic hybrid systems

Abstract

Formulating an optimal operation strategy is a real challenge in the actual operation stage of a hybrid system. This study presented a research framework for determining the short-term optimal operation strategy for cascade hydro-photovoltaic hybrid system. First, a method was presented for describing the cascade hydro-photovoltaic hybrid system net load utilizing the daily average net load and fluctuation coefficient. Second, a model was established for the short-term optimal operation of the cascade hydro-photovoltaic hybrid system. Then, a synchronous peak-shaving strategy of cascade hydropower stations was proposed based on the fluctuation coefficient. Finally, the framework was applied to a case study in the Qinghai Province, China. The results showed an obvious competitive relationship between the two objectives. In the hybrid system, the peak-shaving task is mainly carried out by a daily regulation hydropower station, while its base-load task is jointly carried out by runoff and daily regulation hydropower stations. When the average daily runoff is less than 30% of the hydropower rated flow, the cascade hydro-photovoltaic hybrid system should bear single-peak load on sunny, cloudy, and dusty days, otherwise, it should bear double-peak load. It should bear double-peak load under different daily average runoffs on rainy and snowy days. After the cascade hydropower relative position was interchanged, the cascade hydropower overall peak-shaving capability decreased. Thus, the above results prove the feasibility of the research framework, and it provides a reference for the short-term operation of cascade hydro-photovoltaic hybrid system.