Research On Some Optimization Problems In Power System

According to the features and development tendency of modern electric system, the following 2 items have become important topics in current electric system research and engineering practice. One is to deeply study the features of modern application technologies for electric system, the other is to develop and perfect the optimized models and practical algorithm for modern electric system. This paper deeply studies several problems existing in the course of modern electric system optimization, and studies its practical algorithm. The main works are as following:Under the conditions of ensuring acceptability of operation voltage and promoting the voltage stability, in order to minimize the active power loss in power grid, this paper constructs the multiple-purpose reactive power optimization model integrating safety with economical efficiency. This paper offers multiple-purpose particle swarm algorithm aiming at solving the problem of multiple-purpose reactive power optimization. Aiming at the difficult evaluation in solution quality in Pareto optimal set, this paper uses entropy right decision method to optimize and coordinate different dimensions with multiple purposes. Finally, this paper selects the optimal solution.This thesis offers one kind of improved artificial immune algorithm which takes different mutation strategy toward different unit that has various quality. This algorithm conducts self-adapt adjustment between mutation rate and crossover rate in order to achieve balance between search accuracy and search efficiency. This paper conducts DAIA-BPNN short-term power load forecast model based on DAIA algorithm. It uses DAIA algorithm to optimize the weight and threshold of BPNN while overcoming the blindness when selecting the weight and threshold of BPNN. The actual calculation example of the short-term power system load forecast shows that the method presented in this paper has higher forecast accuracy and robustness compared with artificial neural networks and regression analysis model.Using the power lines maintenance plan of Liaoning Electric Power Company as background, and according to the chromatic theory of graph theory, this paper constructs the optimized model for power grid maintenance, and introduces the concept of cost-benefit analysis. Further, this paper uses AHP(analytic hierarchy process) and offers one kind of improved fish swarm algorithm in order to get the optimized solution. The algorithm in this paper uses roulette method to select mobile activity, and spontaneously adjusts mobile strategy and activity parameter so as to overcome the shortcomings of basic fish swarm algorithm including slow convergence speed and tendency into local optimal solution.This thesis introduces the concept of residential unsatisfactory degree. Based on the idea of physical programming, this paper constructs multiple-purpose and multiple-region model for power limiting in peak load shifting control. This model not only covers economical efficiency of electricity distribution, but also covers its social benefit, which makes this model itself more feasible. According to fuzzy decision theory, this paper further offers multiple-purpose and multiple-region coordinating and control strategy for power limiting in peak load shifting control.The mathematical models and optimized control methods constructed in this paper have all been tested through simulating tests. The result of the tests shows that all the models and methods are reasonable and feasible.