毕业设计-安旭梅.doc

摘　　要 电力系统无功优化的合理分布是保证电压质量和降低网络损耗的前提条件。电力系统中无功优化调整，将对电力系统的安全和经济运行产生着重要作用。因此，对电网进行无功优化，是一个既直接影响系统电压质量，又关系到电网经济运行的重要问题，具有理论意义和实际价值。 本文首先介绍无功功率对电力系统的影响和电力系统无功优化领域的研究现状，接着在深入研究电力系统无功优化的基础上，分析电力系统的无功优化模型和常用的无功控制设备，并重点介绍潮流计算的数学模型和基于PQ分解法的潮流计算方法。本文选用改进遗传算法求解电力系统无功优化问题，并建立以有功网损最小为目标函数的电力系统无功优化计算的数学模型，对于在目标函数中出现的电压越界和发电机无功越界情况，本文采用罚函数进行处理。本文对简单遗传算法进行改进，内容主要涉及混合编码方式、初始种群的产生方式，并采用模拟退火思想在遗传算法的执行过程中对个体适应度不断地进行修正，用自适应算法对遗传算法的交叉、变异策略进行改进等。改进遗传算法在寻优过程中能够很好地跳出局部最优解，增强全局寻优能力，提高计算精度，同时具有简单遗传算法的优点。 为验证上述改进算法的可行性和优越性，本文选用IEEE14节点系统作为优化对象，利用MATLAB语言编写该算法的实现程序，并与简单遗传算法的优化结果进行分析比较。计算结果表明本文的改进遗传算法满足无功优化的基本要求，具有更好的收敛性，提高了算法的收敛速度，同时结果也证明本文模型和算法的实用性、可靠性和优越性。 关键词：电力系统；无功优化；潮流计算；改进遗传算法；数学模型 Abstract Rational distribution of reactive power in power system is the prior condition which can ensure voltage quality and reduce the loss. Optimization adjustment of reactive power will play an important role in secure and economical operation of power system. Therefore, reactive power optimization of power network is a major issue which directly influences voltage quality of the system as well as which relates to economical operation of power network, and has the great significance in theory and the practical application value. Firstly, this thesis introduces the impact of reactive power and research actuality of reactive power optimization in power system, and then on the basis of lucubrating the reactive optimization of power system, analyzing the reactive power optimization model of the power system and the reactive power control equipment used commonly in the power system, and focuses on the mathematical model of the power flow calculation and calculation method based on PQ decomposition method. This thesis applies modified genetic algorithm to solve reactive power optimization problem, and establishes mathematical model of power system reactive power optimization calculates and the objective function of model based on active loss minimum, and the penalty function is used to deal with cros