Abstract: This paper develops an optimal operation model of hydropower unit operation for hydropower stations considering hydro-photovoltaic coordination and economy to reduce the fluctuation of photovoltaic outputs and improve the power generation efficiency of a hydro-photovoltaic complementary integrated system (HPCIS). We examine a study case of the Zangmu hydropower station, with the largest installed capacity in Tibet, and its planned photovoltaic power station, focusing on three typical days－sunny, cloudy and rainy days. For a HPCIS, this model uses the average fluctuation value of the total system output to describe its coordination, and represents its economy by the sum of the electricity benefit of comprehensive hydro-photovoltaic output and the compensation benefit of hydropower rotating reserve. For the typical days in dry season, a transformation relationship between system coordination and economy is revealed, and the daily operation behavior of hydropower and photovoltaic power generation is examined. The results show that for a HPCIS, an obvious competitive relationship exists between its coordination and economy. The average fluctuation of its total system output on the sunny, cloudy and rainy days is reduced from 3.5 MW to 2.5 MW, and the corresponding economic benefits are only reduced by 0.62%, 0.38% and 0.22%, respectively, improving its coordination and economy.

Key words: hydro-photovoltaic complement, typical day, coordination, economy, unit output distribution of hydropower station