Study For Short Term Load Forecasting Of Power System

Short term load forecasting (STLF) is the precondition of economic and secure operation of power system,STLF with high quality is getting more and more important and exigent along with the marketable of power system. Base on the in-depth study of load forecasting methods and the sum-up of latest research productions, the theories such as Kalman filter, artificial neural network (ANN) and fuzzy logic are integrated into STLF in the thesis.Since a mass of historical load data is needed in STLF and the validity of it have a straight relation on the veracity of forecasting result, pretreatment with filling vacancy and getting rid of outliers is indispensable before forecasting. Load data are regarded as state variable and the stochastic state space model of power load is established in the thesis. The Kalman filter is used to eliminate the outliers, moreover the variety of residual difference is introduced to the distinguish standard of outliers. It made the determination more exactly and can avoid the mistaken judgement. From this way it can advanced the filtering precision and provide the most effective data swatch muster for STLF.Power load data are usually classified into elementary heft and mutative heft,To the former method of ANN is considered effective , the classical method for training a multilayer feed-forward ANN called back-propagation(BP) algorithm is used to forecast the elementary load in the thesis,which is good at approaching the nonlinear relations. The optimal estimation theory of Kalman filtering is integrated into BP algorithm, which estimate the network weights as the state vectors of the extended Kalman filter. As result the iterative convergent rate is quicken and the shortcoming of local convergence is improved. To the mutative load, fuzzy logic deals with the factors such as air temperature and holidays, etc,It modify the result forecasted by ANN. So base on the characteristics of Kalman filter, ANN and fuzzy logic, a combined load forecasting model is presented.The combined load forecasting model is used in application of the short-term load forecasting of Changsha power system. The case proves that the algorithm proposed this thesis is effective and veracity.