Optimal Economic Dispatch With Speed Constraints And Their Applications In Wind-thermal Power Systems

Power system restruction tries to introduce market competition that results some fundamental changes in the operation of power generation and distribution. How to dispatch the load demands is very important to a power plant with multiple generation units. Without changing the turbine sets, optimally dispatching the load is a cheap and efficient way to bring down the cost of electric power.Economic dispatch(ED) is a high-dimensional, non-convex, and constrained optimization problem. Ideally the load is distributed based on coal consumption characteristics to minimize the total cost. In order to adapt to the new mode of electric power market in China and to contrapose the greater difference gap between the peak and the valle loads, and to meet the load demand from the power network rapidly, this paper proposes an optimal load dispatch model with velocity constraint. This dispatch problem was discussed but solved via choosing a weight between the total cost and the response speed. It does not reflect the practical requirement of load dispatch. A new load dispatch and unit commitment model with velocity constraint is presented in this paper. The total cost is minimized with a specified response speed of a power plant, which is practical and helps to improve the plant competition ability at the power market.The proposed method is applied to the dispatch problem of power systems with thermal power plants and wind power generation. An hierarchical optimization is adopted in this method. At the power grid level, the wind power combined to the grid was computed incorporating the load tracking speed of each plant. After that, the load demands for power plants are computed. At the power plant level, the load demand is dispatched to each unit according to the consumption characteristics.Simulation result for a three thermal power plants and one wind farm test system shows that the proposed method is effective.