Medium And Long-term Load Forcast Of Power System

Load forecast is the basic issue to ensure the stable and economical operation of power system. For a power system, the increase of stability and economy are all based on the load forecast that must be carried out precisely. Midterm and long-term load forecast take five and ten years as its counting unit. They are often used in power planning utilities that includes the capacity, type, installation site and time of construction of new power plants. It also directs the construction of power grid as well. Load forecast can present reliable basis of the developmental speed in a specified area, and how much fund should be invested in power system construction, and the proper layout of power system, and balance of power among neighboring areas.The central problem of power system load forecast is the proper use of certain mathematical method, and this article discusses the detailed aspects and characteristics of several forecast methods used in load forecast. After the analysis of possible factors that might affect the power system load forecast, the load forecast can be roughly divided into two stages. In the first stage several forecast models will be selected, and the result is the combination of the output of these models. Then the weight of each output must be optimized to make the result more accurate. After the evaluation of multiple forecast methods, the author chooses the grey model, Compertz incremental curve and linear regression to be used in the load forecast of a certain area. This method can take full advantage of the grey model, which has convenient operations andrequires few data. The results can be checked up easily and it doesn't need to take much consideration of the distribution rule and changing trend. The developmental trend of electrical load is obtained though the use of incremental trend forecast method, and this is used to forecast the future growth of electrical load. GDP is also used as an important factor in the linear regression forecast because of its strong correlation with the electrical load level. So the author uses as much forecast models as possible to fulfill the need of proper demonstration of the multitude of electrical load developmental trend. The combination of these methods is also taken into consideration, and optimized combined forecast model is used to increase the accuracy of forecast, and a relatively more precise result can be produced.After the discussion of the load forecast method, the load forecast of a specific power system is carried out using this method. This utility demonstrates the feasibility of the method.