ABSTRACT
With the rapid development of technology and people’s living standard, a higher demand of power quality for the electricity customers is required, and the power intermittence will impact on production and life seriously more and more. Therefore it is particularly important to ensure the continuity of power supply to the customers. In order to improve the reliability of the distribution network power supply, Foshan distribution network dispatch began to try loop closing operation.
Owing to the unobservable distribution network, many factors, such as the voltage and phase angle differences between the loop-closing switch, the complex operating parameter of the distribution line, and the unpredictability of changing the main power network operation modes, will affect the loop closing operation. The above factors would result in complexity to the loop closing operation, and maybe produce huge circulating current and lead to malfunction of the overcurrent protection of the distribution lines, and then affect the power supply for the customers. Currently, State Grid and China Southern Power Grid, as well as abroad grids, develop much exploration on loop closing operation generally concentrating in the areas of theoretical calculations. The exploration methods are generally monotonous and the results differ considerably from the quantitative calculation and actual loop-closing result. These differences may result in misleading decision to loop closing operation. This paper does research on the Foshan power grid situation, mainly includes:
1) Starting from the structure characteristics of regional power network, this paper analyzed and presented 10kV loop closing operation types. Based on it, the paper proposed calculation model of the loop closing operation, and the calculation model can be simplified in actual application, which can simplify the quantitative calculation of large parameters to quantitative calculation of the simplified network and provide references to loop-closing risk assessment through the possible consequences multiplied by the probability of occurrence.
2) According to the situation of Foshan 10KV Distribution network and the mass data analysis, it presented six types of loop-closing calculation program and calculate the success rate of different loop-closing programs to estimate the loop-closing operational risk assessment for Foshan 10KV Distribution network integrally.
3) It stated loop-closing influencing factors and then gave some meaningful quantitative conditions to loop closing operation. Combined with engineering practical problems, this paper gave gradual correction to the various elements of the risk assessment and proposed suitable risk assessment methods to Foshan 10KV network loop closing operation, which could provide advice and help for promoting the loop closing work. Key words: Loop-closing, Risk Assessment, Distribution Network
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目 录
摘 要 ........................................................................................................................................ 1 目 录 ........................................................................................................................................ 1 第一章 绪 论 ............................................................................................................................ 1 1.1研究意义 .......................................................................................................................... 1 1.2 研究现状 .......................................................................................................................... 2 1.3本文主要研究内容 .......................................................................................................... 3 第二章 佛山电网10kV合环转电影响因素分析 ................................................................... 5 2.1 10kV合环方式的分类 ..................................................................................................... 5 2.2 10kV合环转电影响因素分析 ........................................................................................ 8 2.2.1合环网络等值 ............................................................................................................ 8 2.2.2合环稳态电流计算模型 ............................................................................................ 9 2.2.3合环冲击电流 ...........................................................................................................11 第三章 佛山电网10kV合环风险整体评估 ....................................................................... 13 3.1 佛山电网合环情况 ........................................................................................................ 13 3.1.1 合环点阻抗情况 ..................................................................................................... 13 3.1.2 合环方式分布 ......................................................................................................... 16 3.1.3馈线载流量统计 ...................................................................................................... 17 3.2 合环计算条件 ................................................................................................................ 18 3.2.1 电压向量范围 ......................................................................................................... 18 3.2.2 不同合环方式母线电压相角差范围 ..................................................................... 20 3.3 合环成功率计算分析 .................................................................................................... 21 3.3.1 方案一 ..................................................................................................................... 22 3.3.2 方案二 ..................................................................................................................... 22 3.3.3 方案三 ..................................................................................................................... 23 3.3.4 方案四 ..................................................................................................................... 24 3.3.5 方案五 ..................................................................................................................... 24 3.3.6 方案六 ..................................................................................................................... 25 3.3.7 结论 ......................................................................................................................... 26 3.4 环路阻抗对合环成功率影响分析 ................................................................................ 26 第四章 佛山电网10kV合环操作风险个体评估 ................................................................. 28
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4.1 合环操作风险评估量化 ................................................................................................ 28 4.2 风险值计算方法 ............................................................................................................ 28 4.2.1 后果值 ..................................................................................................................... 28 4.2.2 概率值 ..................................................................................................................... 29 4.3风险的控制 .................................................................................................................... 31 4.4简化网络潮流计算 ........................................................................................................ 31 4.5应用实例 ........................................................................................................................ 36 结 论 ...................................................................................................................................... 38 参考文献 .................................................................................................................................. 39 攻读硕士学位期间取得的研究成果 ...................................................................................... 40 致 谢 ...................................................................................................................................... 41
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