电力系统中性点接地方式及其运行分析研究
摘 要
电力系统中性点接地方式是一个非常综合的技术问题，它与电网电压等级、电网结构、对象类型、绝缘水平、供电可靠性、继电保护、电磁干扰、人身安全都有很大的关系。电力系统中性点接地方式的选择涉及到技术水平、经济发达程度和安全性等多个方面，基于各个国家和地区电力技术的水平、条件和运行经验等因素的不同，中性点接地方式也不尽相同。掌握各级电力系统中性点采用何种接地方式，对于电力系统专业的学生以及实际操作的工作人员都具有很重要的理论和现实意义。
本论文简单介绍了各种中性点接地方式在国内外的发展和现状，并对中性点不同接地方式进行对比，包括中性点直接接地，中性点经消弧线圈接地，中性点不接地，中性点经电阻接地四种常见接地方式的特点和问题，并对其各自的原理、适用范围和优缺点等进行理论分析。
通过具体算例（10kV大型公共设施供电系统）来建立数值计算模型，对不同中性点接地方式电网的过电压等级和短路电流大小进行计算，根据相关标准规范，选定恰当的中性点接地方式及接地设备。
关键词：配电网；中性点接地方式；单相接地故障；短路电流
ABSTRACT
It is an important technical problem to neutral grounding mode of the electric power system which associates with voltage level, network structure, object type, insulation level, and reliability of power supply, protective relaying, electromagnetic interference, and personal safety. The selection of neutral grounding mode is relevant to many aspects such as technology level, economic development and security demand. The selection of the neutral grounding mode varies according to the level of electric power technology, operation experience and other factors of the power system. For the power system professional students and the actual operation staff, mastering the selection of neutral grounding mode under different conditions has a very important theoretical and practical significance.
In the thesis, the development and current status of the neutral grounding technologies at both home and abroad are been introduced, as well as the theoretical analysis of the advantages and disadvantages of different modes, including direct neutral grounding, neutral grounding through arc suppression coil, neutral ungrounding and neutral grounding through resistance.
Numerical model is been created through specific examples (10kv large public facilities supply system). Calculate the overvoltage and short circuit current level in different neutral grounding modes, selecting appropriate neutral grounding mode and equipment according to relevant principle.
Key words: Power distribution network, Neutral grounding mode, Single-phase grounding fault and Short-circuit current.
目 录_Toc357347651
第1章 绪论
1.1 论文研究的目的和意义 .................................................................................. 1 1.2 中性点接地方式在国外的发展和现状 .......................................................... 1 1.3 中性点接地方式在我国的发展和现状 .......................................................... 3
1.3.1 中性点接地方式在我国的发展 ............................................................ 3 1.3.2 目前我国的10KV配电网中性点接地方式 .......................................... 5 1.4 本论文的主要内容 .......................................................................................... 6
第2章 中性点接地方式的选择
2.1 电力系统中性点接地方式的类型 .................................................................. 7
2.1.1 中性点有效接地方式 ............................................................................ 7 2.1.2 中性点非有效接地方式 ........................................................................ 8 2.2 影响中性点接地方式的主要因素 .................................................................. 9
2.2.1 供电可靠性 ............................................................................................ 9 2.2.2 电气设备与线路的绝缘水平 .............................................................. 10 2.2.3 继电保护的可靠性 .............................................................................. 10 2.2.4 人身安全 .............................................................................................. 11 2.2.5 设备安全 .............................................................................................. 11 2.2.6 通信干扰 .............................................................................................. 12 2.2.7 其他影响因素 ...................................................................................... 13
第3章 四种常见的中性点接地方式
3.1 中性点不接地方式 ........................................................................................ 14
3.1.1 中性点不接地原理综述 ...................................................................... 14 3.1.2 中性点不接地运行状况分析 .............................................................. 14 3.1.3 中性点不接地系统的特点 .................................................................. 15 3.2 中性点经消弧线圈接地方式 ........................................................................ 16
3.2.1 中性点经消弧线圈接地原理综述 ...................................................... 16 3.2.2 中性点经消弧线圈接地运行状况分析 .............................................. 16 3.2.3 中性点经消弧线圈接地系统的特点 .................................................. 17
3.3 中性点经电阻接地方式 ................................................................................ 18
3.3.1 中性点经电阻接地的运行原理 .......................................................... 18 3.3.2 以电缆线路为主的城市电网的特点[5] ............................................... 18 3.3.3 中性点经电阻接地系统的分类 .......................................................... 19 3.3.4 中性点经电阻接地系统的特点 .......................................................... 19 3.4 中性点直接接地方式 .................................................................................... 20 3.5 中性点接地方式的比较 ................................................................................ 21
第4章 10kV配电网中性点接地方式分析确定
4.1 10kV配电网电路结构图 ............................................................................... 23 4.2 单相接地故障计算 ........................................................................................ 25
4.2.1 开关1断开，开关2断开 .................................................................. 27 4.2.2 开关1闭合，开关2断开 .................................................................. 28 4.2.3 开关1断开，开关2闭合 .................................................................. 29 4.2.4 开关1闭合，开关2闭合 .................................................................. 30 4.3 10kV配电网接地方式的选择 ....................................................................... 30 4.4 柴油发电机供电状态下的故障计算 ............................................................ 31
4.4.1 并列开关断开状态 .............................................................................. 33 4.4.2 并列开关闭合状态 .............................................................................. 34 4.5 柴油发电机供电状态下中性点接地方式的选择 ........................................ 34
4.5.1 发生单相接地故障时不要求瞬时切机 .............................................. 35 4.5.2 发生单相接地故障时要求瞬时切机 .................................................. 35
第5章 总结与展望 .................................................................................. 39 参考文献 ...................................................................................................... 40 致 谢 ...................................................................................................... 42
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