35kV变电站电气设计

摘要

变电站是改变电压的场所。为了把发电厂发出来的电能输送到较远的地方，必须把电压升高，变为高压电，到用户附近再按需要把电压降低，这种升降电压的工作靠变电站来完成。变电站的主要设备是开关和变压器。按规模大小不同，称为变电所、配电室等。

随着现代工业的不断发展，人们对电力供应的要求越来越高，特别是供电的安全性、可靠性和稳定性。然而电网的安全性、可靠性和稳定性往往取决于变电站的设计和配置。出于对这几方面的综合考虑，本论文设计了一个35kV的降压变电站。

本次设计首先对负荷进行了分析与计算，根据负荷的大小选取主变压器型号，然后根据主接线的经济可靠、运行灵活的要求，为各电压等级选择接线方式，在技术和经济方面进行比较，灵活选取最优的接线方式。设计中还进行了短路电流的计算与高压设备的选择与校验，如高压断路器、高压隔离开关、高压熔断器、电压互感器、电流互感器等。此外设计还进行了防雷保护的计算与整定来保障整个系统的安全运行。

关键词：35kV变电站，变压器，防雷保护

Abstract

The substation is a place to change voltage. In order to make the electric energy transport from the power plants to distant places, the voltage must be taken rise to become high voltage, and then according to the users’demand, the voltage should be reduced correspondingly. Above the work is completed by the substation .The main equipments of substation are switchgears and transformers. According to the different scale of the substation, the place is called power substation or power distribution room,etc..

With the development of modern industry, the demand of power supply is increasingly become higher and higher, especially the power supply safety, reliability and stability. However, the security, reliability and stability of power system are often depends on the substation’s design and configuration. By considering the several aspects, this thesis de- signed a 35kV step-down substation.

First, this design has carried on the analysis and calculation of the load, according to the size of the load select the main transformer model, then according to the main-wiring’s requirements of economical, reliable, and flexible to select the connection mode for different voltage level. Compare in the aspects of technology and economy, select the optimal way of wiring flexibly. The design also carried out the calculation of short-circuit current as well as the selection and checking of the high pressure equipment, such as high-voltage circuit breaker, high-voltage isolator,

high-voltage fuse, voltage transformer, current transformer, etc.. In addition, this paper also including the design and setting calculation of lightning protection to guarantee the security of the whole system.

Key Words:35kV substation，transformer，lightning protection

目录

摘要...............................................................................................................................I Abstract ......................................................................................................................... II 第1章绪论 (1)

1.1 我国电力系统发展概述 (1)

1.2 变电站建设的必要性 (1)

1.3 本设计的目的和意义 (1)

第2章负荷计算与变压器选择 (2)

2.1 负荷计算的必要性 (2)

2.2 负荷计算的方法 (2)

2.2.1估算法 (2)

2.2.2 需要系数法 (3)

2.2.3二项式法 (3)

2.3 变电站原始资料及分析 (4)

2.4 主变压器的选择 (8)

2.4.1 主变压器容量的确定原则 (8)

2.4.2 主变压器台数的确定原则 (9)

2.5 功率因数和无功功率补偿 (9)

2.5.1 计算功率因数的方法 (9)

2.5.2 提高功率因数的方法 (10)

2.5.3 并联电容器补偿 (11)

第3章电气主接线方案的确定 (15)

3.1 电气主接线的基本要求 (15)

3.2 电气主接线方案的比较 (15)

3.2.1 35kV侧接线方案的确定 (15)

3.2.2 10kV侧接线方案的确定 (17)

第4 章短路电流计算 (18)

4.1短路电流计算的意义 (18)

4.2 短路电流的计算方法 (18)

4.2.1 标幺制法 (18)

4.2.2 各元件阻抗标幺值的计算 (19)

4.2.3 三相短路电流的计算 (20)

第5章变电站电气设备的选择与校验 (23)

5.1电气设备选择的意义及原则 (23)

5.1.1 电气设备选择的意义 (23)

5.1.2 电气设备选择的一般原则 (23)

5.2高压断路器的选择与校验 (24)

5.2.1 35kV侧高压断路器的选择与校验 (24)

5.2.2 10kV侧高压断路器的选择与校验 (25)

5.3 高压隔离开关的选择与校验 (27)

5.3.1 35kV侧高压隔离开关的选择与校验 (27)