Study on mid- and long-term multi-objective optimal operation of cascade reservoirs considering water abandonment risk

Aiming at the problem of significant deviation between the calculation results of abandoned water risk in existing hydropower stations and the actual situation, based on the principle of water balance, a cascade reservoir abandoned water risk quantification method coupling runoff and load dual uncertainties was proposed by identifying abandoned water risk factors. The concept of critical abandonment probability was introduced, and a method for determining the critical abandonment probability of cascade reservoirs based on the joint minimum of warning false alarm rate and missed alarm rate, as well as a method for controlling the water level drop of cascade reservoirs at the end of the water supply period based on the critical abandonment probability, were proposed. On this basis, a mid- and long-term multi-objective optimal operation model considering the abandoned water risk in cascade reservoirs was constructed, and a case study was conducted on the Wujiang cascade reservoir group. The results show that there is a significant monotonic increasing relationship between the abandoned water probability and the abandoned water flow rate in the Wujiang cascade reservoir group. The two-stage scheme of coupling operation period and residual period has increased the power generation efficiency by about 0. 51% compared to the conventional optimized scheduling scheme, and the ecological efficiency has increased by about 1. 06 times.