Multi-objective Hierarchical Optimal Scheduling of Combined Power Systems Considering Base Loads

To overcome the disadvantages of wind power on dispatching such as the randomness and intermittentness, and exert the flexible adjustment ability of high-proportion hydropower. The optimization goal is set to promote full consumption of wind power, lowest operating cost of thermal power and minimum output fluctuation, then a multi-objective optimal dispatch model for wind-hydro-thermal power systems is established to evaluate the results of dispatch. We considered a variety of scenarios such as start-stop and low-load operation of thermal power generator and whether wind power has abandoned wind, some quantitative indicators such as hydropower utilization rate and thermal power fluctuations are proposed. And hierarchical optimization strategy is designed to ensure the efficiency in solving model, first layer optimizes output of hydropower generators, ensures minimum total fluctuation of thermal power, and promotes full use of hydropower adjustment ability, second layer optimizes output of each thermal power generator to make the system operation cost the lowest, and uses particle swarm optimization (PSO) algorithm to solve each layer optimization problem. Through experimental test, the scheduling results before and after optimization, the scheduling results considering the start-stop of power unit, and the scheduling results under different wind power installed capacity are compared, and the effectiveness of the proposed model and hierarchical optimization strategy is verified.