微网的经济运行优化研究

发布时间：2018-08-24 10:07

【摘要】：作为分布式电源的有效组织形式和大电网的有力补充,微网已成为世界各国智能电网的发展方向之一。研究微网的经济运行优化模型、调度模式和算法,合理地安排微网内部微电源的工作状态和对负荷进行管理,可以节省微网的运行成本和减少污染物的排放。本文采用集中分层控制的思想,在对分布式电源特性研究的基础上,建立了微网经济运行的多目标非线性混合整数规划模型。该模型以运行成本最小、污染物排放最少为目标,考虑了储能单元电量和充放电功率限制、微电源最大爬坡率限制、微电源最小启停时间限制等多种约束条件,同时,该模型将微电源的启停状态作为决策变量,从而更加合理地描述微电源的状态,也使该模型成为一个混合整数规划模型。针对微网的调度模式,分析了微网的并网运行模式、带可控负荷缩减策略的孤网运行模式、微电源的优先调度模式及电价策略,提出了保留一定储能单元电量以增强系统稳定性的电量保留模式及其实现方法。由于微电源最大爬坡率、最小启停时间以及储能单元电量的限制,使得相邻时间断面的优化具有很强的耦合性,本文对此提出了有效的处理办法,使微网的调度由动态调度转化为静态调度。针对微网经济运行多目标优化模型所具有的非线性、混合整数特征,提出了基于ε-约束法和基于NSGA-Ⅱ的两种求解方法。在基于ε-约束法的求解中,针对问题的混合整数和非线性特征,结合分支定界法和内点法对子问题进行求解,提出了将部分等式约束转化为处理过程的方法,减少了约束的数量。进一步采用两种改进的ε序列产生方法,增强了ε-约束法获得的Pareto最优解集的均匀性。在基于NSGA-Ⅱ的求解中,采用分段函数的方式构建评价函数,用以处理模型中的不等式约束条件,并通过等价转化的方式去除了模型中的等式约束,提高了求解效率。为了提高初始种群的多样性,提出了基于随机方法的种群初始化和基于ε-约束法的种群初始化方法。本文给出了两种Pareto最优解集决策方法,从获得的Pareto最优解集中挑选出一个满意解,作为微网单元级控制器MC和LC的设定值。最后,以一个典型的微网系统为例,对本文所提出的微网经济运行多目标优化模型及其求解算法进行验证,并分析了满意解的决策方式对微网运行的影响。优化的结果表明,本文提出的多目标求解方法是有效的,动态调度处理方法是合理的。
[Abstract]:As an effective organizational form of distributed generation and a powerful complement to large power grid, micro-grid has become one of the development directions of smart grid in the world. Researching the economic operation optimization model, dispatching mode and algorithm of micro-grid, reasonably arranging the working state of micro-grid and managing the load can save the operation of micro-grid. In this paper, a multi-objective nonlinear mixed integer programming model for the economic operation of micro-grid is established based on the study of the characteristics of distributed generation by using the idea of centralized hierarchical control. At the same time, the start-stop state of micro-power supply is taken as a decision variable to describe the state of micro-power supply more reasonably, which makes the model a mixed integer programming model. Grid-connected operation mode, isolated operation mode with controllable load reduction strategy, priority dispatching mode of micro-power supply and electricity price strategy are proposed. The power reserve mode and its implementation method are put forward, in which a certain amount of energy storage unit is reserved to enhance the stability of the system. In view of the nonlinear and mixed integer characteristics of the multi-objective optimization model for the economic operation of micro-grid, two kinds of solutions based on the epsilon-constraint method and NSGA-II are proposed. In the solution based on the epsilon-constrained method, considering the mixed integer and nonlinear characteristics of the problem, the branch-and-bound method and the interior point method are combined to solve the sub-problem. A method of transforming partial equality constraints into processing procedures is proposed to reduce the number of constraints. In the solution based on NSGA-II, the evaluation function is constructed by means of piecewise function to deal with the inequality constraints in the model, and the equality constraints in the model are removed by means of equivalent transformation to improve the efficiency of the solution. In this paper, two Pareto optimal solution set decision-making methods are given. A satisfactory solution is selected from the Pareto optimal solution set, which is used as the settings of MC and LC. Finally, a typical micro-grid system is taken as an example. The multi-objective optimization model for economic operation of micro-grid and its solving algorithm are validated, and the influence of the decision-making mode of the satisfactory solution on the operation of micro-grid is analyzed.
【学位授予单位】：东北大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TM732

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