大电网短路电流限制措施研究

【作者】 陈怡静；

【导师】 黄民翔；

【作者基本信息】 浙江大学 ， 电力系统及其自动化， 2008， 硕士

【摘要】 随着电力系统规模的扩大和电网的不断加强,电力系统中短路电流水平逐年增大,目前已成为电力系统规划、运行方面面临的重要问题。同时电力市场化的不断推进,对主网架的电力输送能力和可靠性提出了更高的要求,因此有效控制短路电流水平,寻找限制短路电流的合理而经济的方法是电网发展面临的重大挑战之一。基于有效而经济的控制全网短路电流水平的目的,本文建立了数学模型寻找成本最优的限流方案,综合考虑多种限流措施,利用遗传算法求解。该方法对18节点进行了计算,结果表明了模型的合理性,算法能够得到经济最优的限流方案。本文基于2008至2020年宁夏电网的结构和运行特点,分析宁夏电网短路电流增加的趋势和原因;结合宁夏750kV电网的建设和发展,对各种限流措施进行了探讨和分析。计算结果表明:采用高阻抗变压器可以缓解750kV变电站附近地区超标情况;随750kV电网的逐步强壮,分层分区是控制全网短路电流水平的最优措施;部分节点开关遮断容量过小已成为限制电网发展的瓶颈,应更换开关;开断线路可以作为过渡措施;对于远景网架,采用串联电抗器可以作为局部地区限制短路电流的措施。本文从措施实施的连续性、一致性出发,提出宁夏电网2008至2020年综合限流方案。主要措施为改造现有网架结构,辅以升级改造现有设备以及增加限流装置,达到整体限流效果最优。方案一的首要目的为减小短路电流水平,方案二的在减小短路电流的基础上,在经济最优的前提下,尽可能提高提高系统承受短路电流的能力。计算结果表明综合限流方案能够将全网短路电流控制在合理范围,并满足电网运行要求。更多还原

【Abstract】 With the expansion of power system, short-circuit current is increased year by year, which has become a serious problem for the planning and operation of power system. Besides, a heathier power market will set higher standards for transmission capability and reliability of power gird. Therefore, to effectively control the level of short-circuit current and find reasonable and economical limitation methods is one of the big challenges standing on the way of power system development.Aiming to effectively control the short-circuit current level for the whole power network, a mathematical model is built to find limitation solution with lowest investment, taking several different methods into consideration and using Genetic Algorithm to search for the global optimal solution. Tests on the 18-bus system show that the model is effective and reasonable.Based on the characters of framework and operation in the planning network of Ningxia province from 2008 to 2020, both of the increasing trend and deep-rooted causes for short-circuit current are analyzed; Taking the construction and development of 750kV electrical network in Ningxia province as background, thesis researches the measures which can limit short circuit currents. Simulation results show that: to adopt high impedance transformer can bring notable decrease of short-circuit current at the adjacent area of the 750kV substation; dispatching by levels and districts will be the best method to control short-circuit current globally as the 750kV power network becomes robust; to improve the interrupting capacity for some breakers which are too low and become the bottleneck for power system development is necessary; line-cutting can be a temporary measure; for 2020-yeat gird, installation of series rector is useful to reduce short-circuit current as a local limitation mothod.From the angle of measures’ global effectiveness, continuity, limitation solution from 2008 to 2020 are put up, with reconstruction network being the first choice and change transformation devices being the second choice. Solution I aims to reduce short circuit current, and Solution II can not only realize short circuit current control, but also improve the capability of power system to operate in the condition of larger short circuit current. Their validity is proved by calculation.更多还原