Research On Uncertainty Problems In Decision Of Power Economic Systems

With the development of the deregulation to power industries, power system is greatly improved. As relating to power system efficient, economic, safe and reliable real-time operation, and long-term resource adequacy and sustainable development, the decision of power economic systems has attracted more and more attention and becomes a research focus. But the judgments and decisions of power market participants are greatly affected by some uncertainty problems in the decision of power economic systems. In order to keep power market profound and healthy developing, these problems are urgently needed to be deeply researched.From the technical and economical points of view, the dissertation focuses on deeply researching some uncertainty problems of electricity transmission and purchase in the decision of power economic systems.There are many uncertainty problems in every aspect of generation, transmission, distribution and use in the power system. The accuracy of available transfer capability (ATC) evaluation is more affected by the uncertainty factors. For fast ATC evaluation, based on the traditional contingency enumeration method, this dissertation firstly introduces entropy weight, and takes both of the apparent power behavior index and the voltage-reactive power behavior index into account, which is better to mix the objective and subjective factors to order and select the contingency states; then the optimal power flow model is added into the continuation power flow method; lastly the maximum entropy principle is used, and a calculation model which uses the apparent power behavior index of the tie lines as the constraints is proposed to get the occurrence probability of ATC value. For mid long term ATC evaluation, the research achievement of the credibility theory, is used, and the models of the generators, the transmission lines and the loads according to their characteristics of random and fuzzy are built. Then the random fuzzy simulation is the first time applied in the ATC evaluation. And the bootstrap method and multi-core parallel computing technology are used to enhance the speed of processing. Numerical simulations are done in the standard test systems, and show that the two proposed methods are reasonable and effective.Electricity prices are the focus of power markets. Accurate forecasting electricity price has large effects on all participants'benefits. As the mid long term electricity price has the features of poor information and associated uncertainties. The grey system theory is introduced and a multi-electricity price grey model is built to comprehensive forecast the prices of the spot market and the long-term contract market. Then the structure of the background value of the multi-electricity price grey model is further studied, and a simple calculating formula of background value is reestablished which has strong adaptability to the high growth price. The example shows that the multi-electricity price grey model and its improved model have better precision and adaptability.In the power market consumers must face the uncertainties of electricity price in different markets. So based on the modern portfolio theory, the electricity purchasing portfolio decision models with variance, semivariance, VaR, absolute deviation and information entropy as risk measures are built respectively. According to the requirement of getting the global optimal solution of nonlinear programming problems for electricity purchasing, the simulated annealing algorithm is used to solve the five models. The risk elasticity, the calculation time and the iteration times for convergence are adopted as quantitative indices to compare the different models. Finally how to purchase electricity among the spot market, the long-term contract market and the autonomous electricity plant for an enterprise consumer is analyzed as an example, and the above models are compared and some useful guidance conclusion is got.