Multi-Objective Hybrid Optimal Dispatch Of Power Systems

With the permeability of the renewable power, such as the wind power and the solar power increasing in the Grid, the volatility of such uncertain and interrupted power has brought more difficulties for optimal dispatch. At the same time, facing high tension from the environmental and energy problems, the task of saving energy and reducing emissions for China has been implemented widely. Whole of the electric power industry has to accomplish the palnning index of the environmental and energy problems, which is drawn up by the government. Based on the consideration of the energy-saving and emission-reduction indexes, how to formulate the generation schedule and spinning reserve schedule in daily optimal disptch has, become a key problem to be solved.To solve the problems of optimal dispath considering the saving energy and reducing emissions, in the first place, on the base of the research on the model of multi-objective desired value optimation for single time-period power load distribution, this paper sets up the model of multi-objective desired value optimation for multi-time-periods power load distribution. The targets of the model above include the energy consumption, the emission of pollutants, and the Grid Corporation's purchasing cost. The solving method for this model will also be discussed. Comparing with the multi-objective desired value optimation model, this paper will discuss the model of multi-objective hybrid optimation for load distribution. The purchasing cost target will be turned to a desired value controled target, and its solving method will be given as well. Through some examples, the accuracy and practicality of these models and solving methods are verified.In order to consider the wind power's effect on optimal dispath, this paper defines a normalized reserve risk in order to evaluate the tension of the spinning reserve caused by the volatility of wind power, thus establishes the model of multi-objective hybrid optimal dispatch, which can both consider the reserve risk and formulate the generation schedule and spinning reserve schedule at the same time. In this model, the target of Grid Corporation's purchasing cost reaches for the minimum value, and the targets of the energy consumption, emission of pollutants and the reserve risk reach for the desired value.When solving the model of multi-objective hybrid optimal dispatch, a solving method is adopted, which disintegrates the original problem into two sub-problems, the economic load optimal dispatching problem and the spinning reserve optimization problem.Then, it uses the alternating solution according to the specific relationship between the two sub-problems. Examples show that the model can make an overall plan of safty, quality, economy and environment discriminatively, and the sovling method could help reducing the difficulty and increasing the efficiency for caculating.Considering that the PFCA (Primary Frequency Control Ability) of power system can adjust a part of unbalanced active power caused by the fluctuating wind power, based on the previous model of multi-objective hybrid optimal dispatch without the ability of PFCA, the PFCA is added to the model. Then, examples show the different effect on the dispatching work between the two models.When calculating the reserve risks, a proper sampling method will be adopted to forming different scenes of wind power fluctuations, because the width of sampling window will affect the analysis results to some extent. In the last part, to analyze effect of different sampling width through sampling on different wind-speed distribution curves on the reserve plan, the paper defines the index of cost performance and discusses the sampling method with better cost performance.This work was conducted as a part of the Project 50877014 supported by Natural Science Foundation of China and the Project 20102302110021 supported by Specialized Research Fund for the Doctoral Program of Higher Education.