Multi-objective optimization of a hydro-wind-photovoltaic power complementary plant with a vibration avoidance strategy

Hydropower has the advantages of quickly responding to load variability, which overcomes the unpredictable and unstable variabilities of solar and wind power. Therefore, such power generation can be combined into a hydro-wind-photovoltaic complementary plant (HWPCP). However, hydropower units running at partial load are prone to suffer from hydraulic instabilities generated by a cavitating vortex rope, which may lead to power swings and high vibrations. Operation in these vibration zones may affect the operation and ultimately cause structural damage and affect the power plant. The problem of avoiding running hydropower units in the vibration zones is effectively addressed in this study. This is achieved by adopting a vibration avoidance strategy to determine a rational power distribution scheme for hydropower units. Multi-objective optimization is performed to maximize power generation, minimize output power fluctuations, and minimize the deviation between the power generation and the planned output. The power distribution strategies of hydropower units under 12 scenarios, composed of different inflow and weather conditions, are analyzed. The results indicate that the vibration avoidance strategy effectively avoids the operation of hydropower units in the vibration zones and ensures the operation of hydropower units in the non-vibration zone for more than 99.31% of the operation time. This study contributes to the identification of the relationship between conflicting objectives and provides operational strategies for the safe and stable operation of hydropower units.