In view of the existence of illogical phenomenon of minimum energy consumption related to state shift path of load distribution of cascade hydropower plants in actual application

a study is made of the energy change relation of the cascade system and an analysis is made of the state shift path of cascade hydropower plants. Some improvements are made on the minimum energy consumption model based on a study of the energy change relationships between cascade reservoirs and an analysis of the influences of energy loss of inflow and head loss of tail water on energy consumption of the reservoir. The Wuqiangxi-Lingjintan cascade hydropower system is taken as an example to show that the optimal scheme of the improved model consumes 1. 61% less energy than that of the minimum energy consumption model

which demonstrates that the improved model can more accurately reflect the energy change relationships and laws of cascade reservoir system compared with the minimum energy consumption model. This work is supported by National Natural Science Foundation of China(No. 51379081)and State Grid Corporation of China(No. DKJS-13-00220).