文档介绍：摘要
10kV配电网主要有中性点不接地、中性点经消弧线圈接地、中性点经小电阻接地等运行方式。不同的配电网中性点接地方式各有其特点和优势。本文详细分析计算了三种主要接地方式下配电网在发生单相短路故障时的零序电压、短路电流和暂态特性;并利用有限元分析软件,详细分析了小电阻接地运行方式下,单相短路故障时的大地电场分布,计算了短路点附近的跨步电压。为配电网接地方式的合理选择及继电保护提供了理论依据。
本文研究内容主要包括以下几个方面:
介绍了10kV配电网的不同接地方式发展概况,详细分析了配电网中接地变
压器的结构与工作原理,总结并对比了不同接地方式的优缺点。
针对三种主要接地方式的配电网络,首先分析出了其发生单相短路故障时的稳态等效电路,在此基础上推导出其短路接地电流计算公式,并给出了其电容电流分布图。其次详细推导出其暂态等效电路,同样详细计算了其暂态短路接地电流。最后建立了配电网发生单相接地短路的MATLAB仿真模型,得出了与理论分析结果相符的仿真波形与数据。
阐述了接地电阻、跨步电压和接触电压的概念,详细推导了它们的理论计算公式。开创性地运用有限元分析软件ANSYS来定量仿真发生单相对地短路后的跨步电压,仿真结果与理论计算结果基本吻合。
设计了10kV配电网小电阻接地运行方式下发生单相对地和单相对电线横担的两种常见短路的实验方案,给出了详细实验操作步骤及需要注意的事项,通过实验验证了论文中有关短路时接地电流及跨步电压的计算分析结果。
关键词:10kV配电网;中性点接地方式;短路接地电流;跨步电压;有限元分析
Abstract
Neutral grounding without impedance,neutral grounding through suppression coil and neutral grounding through low resistor are the mon neutral grounding in the l0kV work. There are different characteristics and application advantages with different neutral grounding. When the single phase short-circuit fault occur in the l0kV work, zero sequence voltage, short-circuit current are calculated in detail and transient characteristics are analyzed for the three main neutral grounding in this paper. Then, Electric field distribution and step voltage are also calculated with Finite element analysis software for grounding through low resistor. The study of this paper is helpful to the choice of neutral grounding and power system relay protection for the l0kV work.
The study of this paper focuses on the following aspects:
The development and application trends of neutral grounding in l0kV work are introduced in this thesis, then the structure and work principle of grounding transformer is analyzed in detail. The advantages and disadvantages of three main neutral grounding are summarized pared with each other.
For the three main neutral grounding work, Firstly, the steady-state equivalent circuit is proposed through careful analysis when the single phase short-circuit fault occur and the short circui