考虑冰灾的电网运行风险评估及网络化保护

发布时间：2018-01-06 00:17

本文关键词：考虑冰灾的电网运行风险评估及网络化保护　出处：《哈尔滨工业大学》2014年硕士论文　论文类型：学位论文

【摘要】：2008年初我国南方地区发生特大冰灾，对受灾地区电网的安全稳定运行构成极大威胁。冰灾可能会在短时间内对电网的电力元件造成大量损坏，从而引发电网的群发性故障，严重时甚至导致电网大面积停电和瘫痪。为此，结合冰灾期间的气候信息和电网的运行条件，定量地描述冰灾对电网运行可靠性的影响是十分必要的。本文给出了电力线路在覆冰和风综合作用下故障概率的计算方法，方法通过气象站点加权平均获得的降雨量、风速等信息计算输电线覆冰厚度。从力学的角度出发，分析风速和冰厚对输电线的共同作用关系，给出冰风力的计算方法。基于冰风力，使用反映金属承载极限特性的指数模型，，实现电力线路故障概率的实时计算或预测。同时考虑冰灾致输电线路故障概率与潮流越限对线路故障的影响，形成线路故障模型，基于连锁故障树对冰灾下的电网进行风险评估，计算发生故障的概率和损失负荷大小，研究线路潮流的越限情况，得到系统发生连锁故障的失负荷风险和越限风险，从而算出系统的总风险水平，形成关于连锁故障的事故集。采用气象台站的历史数据和测试电网的算例分析结果表明，该方法能够提供不同线路的故障概率时变情况，为进一步进行电网安全运行风险评估和调控提供相关基础信息。冰灾期间引发电网发生大量的断线倒塔事故，电网拓扑和运行方式频繁发生变化，增加传统继电保护误动拒动的概率，为此，本文提出一种基于广义节点的网络差动保护方法。根据广义基尔霍夫定律的概念建立的网络差动保护数学模型，在线整定动作电流，不受运行方式的影响，能够适应极端天气期间电网结构和运行方式频繁的变化。考虑电网结构和测点的变化以及继电保护装置拒动的情况，提出该广义节点的后备差动保护算法。采用网络化差动保护作为后备保护进行保护配合，能够有选择地快速切除故障线路，缩小故障影响范围，降低连锁故障的风险。本文工作得到国家电网公司重大科技专项五《大电网在线评估技术深化研究》（SGCC-MPLG-023）之课题5《考虑自然灾害的大电网安全在线预警技术》以及国家高技术研究发展计划（863计划）重大项目《高渗透率间歇性能源的区域电网关键技术研究和示范》（2011AA05A105）的资助。
[Abstract]:In early 2008, a severe ice disaster occurred in southern China, which posed a great threat to the safe and stable operation of the power grid in the affected area. The ice disaster may cause a large number of damage to the power elements of the power network in a short time. Therefore, it can lead to the power grid group fault, and even lead to the power grid blackout and paralysis in a large area. Therefore, combined with the climate information during the ice disaster and the operation conditions of the power grid. It is necessary to describe quantitatively the effect of ice disaster on power network operation reliability. This paper presents a method for calculating the fault probability of power lines under the combined action of icing and wind. The method is based on the weighted average rainfall obtained by meteorological stations. From the point of view of mechanics, the relationship between wind speed and ice thickness on transmission line is analyzed, and the calculation method of ice wind force is given. An exponential model reflecting the limit characteristics of metal loading is used to calculate or predict the fault probability of power line in real time. At the same time, considering the influence of fault probability and power flow overrun on transmission line fault caused by ice disaster, the fault model of transmission line is formed, and the risk assessment of power network under ice disaster is carried out based on cascading fault tree. The probability of failure and the loss load are calculated, and the load loss risk and the excess risk of the cascading fault are obtained by studying the over-limit situation of the line power flow, and then the total risk level of the system is calculated. By using the historical data of meteorological stations and the example analysis of test grid, it is shown that this method can provide time-varying fault probability of different lines. It provides basic information for further risk assessment and regulation of power grid safety operation. During the ice disaster, a large number of broken tower accidents occurred in the power network, and the topology and operation mode of the power network changed frequently, which increased the probability of misoperation and failure of the traditional relay protection. In this paper, a network differential protection method based on generalized nodes is proposed. The mathematical model of network differential protection is established according to the concept of generalized Kirchhoff's law. It can adapt to the frequent changes of power network structure and operation mode during extreme weather. A backup differential protection algorithm for the generalized node is proposed. The network differential protection is used as the backup protection to protect and cooperate, which can selectively and quickly remove the fault line and reduce the fault influence range. Reduce the risk of cascading failures. The work of this paper has been obtained from the State Grid Company's major science and technology project five < deepening Research on On-line Evaluation Technology of large Power Grid "SGCC-MPLG-023). Project 5 "Safety online early warning Technology for large Power Grid considering Natural disasters" and National High Technology Research and Development Program. Research and demonstration of key Technologies in Regional Power Grid for High permeability intermittent Energy.
【学位授予单位】：哈尔滨工业大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TM732

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