电力系统恢复的网架重构多目标协调优化

发布时间：2019-06-03 13:32

【摘要】：随着现代社会对电力供应依赖程度的日益提高,大停电事故带来的经济损失和社会影响越来越严重,因此研究大停电事故后如何实现电力系统的快速、安全恢复具有重要意义。网架重构阶段是大停电后系统恢复过程中承前启后的关键环节,该阶段恢复控制的主要任务是通过恢复系统中重要的厂站以及部分输电线路实现骨干网架的构建,并通过输电网络的恢复调整提高已恢复网架的承载能力和系统强度,为网架重构之后的负荷全面恢复奠定基础。网架重构阶段各恢复主体的协调机制、恢复方案的优化策略以及优化方法研究,是制定合理高效的网架重构方案、加快系统恢复进程的核心任务。本文围绕网架重构阶段的核心任务,对送电路径优化、主力机组和特级负荷协调恢复优化、环网恢复决策优化以及网架重构后期的负荷协调恢复优化等问题进行了系统深入的研究,针对不同问题建立了相应的协调优化模型,采用多目标优化技术和先进的数学规划方法进行了求解,论文的主要内容包括:(1)通用的送电路径方案集搜索和评价方法研究。针对大停电后工况复杂多变,线路出现故障的可能性较高的实际情况,按照先确定备选路径集再排序优选的思路开展送电路径优化决策研究。首先,通过对基于最小费用流模型的送电路径优化方法的深入研究,建立了通用的备选路径集搜索的混合整数规划迭代模型。之后,构建了送电路径评价指标集,并结合逼近理想灰关联投影法对备选路径集进行综合评价。提出的送电路径优化方法为调度人员提供了更加全面的决策支持。(2)多目标协调的网架重构分时段全局优化方法研究。将特级负荷纳入网架重构阶段的恢复目标,计及多种约束条件,建立了协调机组、特级负荷和网架结构三方面恢复效果的网架重构分时段全局优化模型。通过对恢复序列的串并行优化模式的分析对比,提出了分时段全局优化模型的两步求解策略,即首先优化确定时段数参考值,再以全局视角对恢复方案进行优化。结合非支配近邻免疫算法和变异系数法对建立的时段数优化模型和全局优化模型依次求解。提出的优化策略克服了“逐步”优化模式在协调各时段恢复决策方面的不足,为实现分时段恢复的全局优化提供了新思路。(3)网架重构中以消除线路过载为目标的环网恢复决策优化方法研究。针对网架重构阶段输电网络尚不完整,在负荷的陆续恢复过程中可能会出现线路潮流过载的问题,提出了以消除过载为目标的环网恢复策略,即通过投运部分待恢复线路,建立局部环状网络,实现线路过载的消除。首先建立了直接计及交流潮流约束条件的混合整数非线性规划模型。进一步地,提出了一种分层迭代方法,通过主问题和子问题间的迭代求解,确定满足合闸角约束的最优环网恢复方案。提出的环网恢复策略可以在消除线路过载的同时有效增强系统强度和承载能力;提出的分层迭代求解算法具有较高的计算效率,对系统恢复的在线决策具有重要参考价值。(4)网架重构后期负荷恢复的多目标优化方法研究。将网架重构恢复后期的负荷恢复过程建模为一系列顺序执行的恢复时段。对负荷投入后系统频率的调节过程以及系统运行要求进行了深入分析,建立了相应的约束集。由于恢复过程需要兼顾恢复收益和安全裕度,将负荷恢复优化建模为加权负荷量最大化和节点电压偏移量最小化的多目标优化问题。引入规格化法平面约束法将建立的多目标混合整数非线性规划问题转化为一系列带有附加线性约束的单目标混合整数非线性规划问题,并采用通用代数建模系统建模求解。提出的负荷恢复优化的多目标混合整数非线性规划模型及求解方法相较于已有方法具有方案可行性高以及计算结果稳定等方面的优势。
[Abstract]:With the increasing of the power supply dependence of the modern society, the economic loss and the social influence brought by the large power failure accident are becoming more and more serious, so it is of great significance to study how to realize the rapid and safe recovery of the power system after the large power failure accident. The reconstruction stage of the net frame is the key link in the process of system recovery after large power failure, and the main task of the phase recovery control is to realize the construction of the backbone network frame through the important plant station in the recovery system and the partial power transmission line. And the bearing capacity and the system strength of the restored net frame are improved through the restoration adjustment of the power transmission network, and the foundation is laid for comprehensive recovery of the load after the frame reconstruction. The coordination mechanism, the optimization strategy and the optimization method of each recovery main body in the reconstruction stage of the net frame are the core tasks of developing a reasonable and efficient network rack reconstruction scheme and accelerating the system recovery process. In this paper, a systematic and in-depth study of the problems such as the optimization of power transmission path, the optimization of the main unit and the special-level load coordination, the optimization of the ring network recovery decision and the optimization of the load coordination and recovery in the later stage of the frame reconstruction is carried out in the paper, The corresponding coordination and optimization model is set up for different problems, and the multi-objective optimization technique and the advanced mathematical programming method are used to solve the problem. The main contents of the paper are as follows: (1) The general power transmission path scheme set search and evaluation method is researched. In view of the complexity and changeability of the working condition after large power failure and the high possibility of the fault of the line, the optimization decision-making of the power transmission path is carried out according to the preferred method of determining the alternative route set. First, the hybrid integer programming iteration model of the universal alternative path set search is established through the deep study of the power transmission path optimization method based on the minimum cost flow model. Then, the evaluation index set of the power transmission path is constructed, and the alternative path set is comprehensively evaluated in combination with the approximate ideal gray correlation projection method. The proposed power transmission path optimization method provides more comprehensive decision support for the dispatching personnel. (2) Research on the global optimization method of the multi-objective coordinated frame reconstruction sub-period. Taking the super load into the recovery target of the frame reconstruction stage, taking into account various constraints, the overall optimization model of the frame reconstruction sub-period with the recovery effect of the coordination unit, the special-level load and the grid structure is established. In this paper, the two-step solution strategy of the time-period global optimization model is put forward by analyzing the parallel optimization model of the serial-parallel optimization of the recovery sequence, that is, the reference value of the determined period number is optimized first, and the recovery scheme is optimized by the global view angle. The time-period optimization model and the global optimization model based on the non-dominant-neighbor immune algorithm and the coefficient of variation are solved in this order. The proposed optimization strategy overcomes the shortcomings of the "step by step" optimization model in the coordination of decision-making in all time periods, and provides a new way to realize the global optimization of the recovery of the sub-period. (3) The optimization method of ring network recovery decision making with the aim of eliminating line overload is studied in the frame reconstruction. aiming at the problem that the power transmission network is not complete in the reconstruction phase of the net frame, the problem that the line power flow overload can occur during the successive recovery of the load is solved, a ring network recovery strategy aiming at eliminating the overload is put forward, namely, a local ring network is established through the operation part to be recovered, And the elimination of line overload can be realized. First, a mixed integer nonlinear programming model directly taking into account the constraints of the AC power flow is established. Further, a layered iteration method is proposed, and the optimal ring network recovery scheme satisfying the closing angle constraint is determined by the iterative solution between the main problem and the sub-problem. The proposed ring network recovery strategy can effectively enhance the system strength and bearing capacity while eliminating line overload, and the proposed layered iterative solution algorithm has higher calculation efficiency and has important reference value for on-line decision-making of system recovery. (4) The multi-objective optimization method of the post-load recovery in the post-reconstruction of the grid. The load recovery process at the later stage of the frame reconstruction recovery is modeled as a series of sequential execution recovery periods. The regulation process of the system frequency after the load is put into operation and the operation requirement of the system are analyzed in detail, and the corresponding constraint set is established. Because the recovery process needs to balance the recovery benefit and the safety margin, the load recovery optimization is modeled as a multi-objective optimization problem that maximizes the weighted load and minimizes the node voltage offset. The multi-objective mixed integer nonlinear programming problem is transformed into a series of single-target mixed integer nonlinear programming with additional linear constraints, and a general-purpose algebraic modeling system is used to model and solve the problem. Compared with the existing method, the multi-objective mixed integer nonlinear programming model and the solution method for load recovery optimization have the advantages of high scheme feasibility and stable calculation result, and the like.
【学位授予单位】：华北电力大学(北京)
【学位级别】：博士
【学位授予年份】：2017
【分类号】：TM732

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