摘 要
电力已成为人类历史发展的主要动力资源，要科学合理的使用及分配电力，必须从工程的设计来提高电力系统的安全性、可靠性和运行效率，从而达到降低成本，提高经济效益的目的。变电站是电力系统配电传输不可缺少的重要组成部分，它直接影响整个电力网络的安全和电力运行的经济成本，是联系发电厂和用户的中间环节，起着变换和分配电能的作用。电气主接线是发电厂变电所电气部分的主体，电气主接线的拟定直接关系着全厂（所）电气设备的选择、配电装置的布置、继电保护和自动装置方式的确定，对电力系统的安全、可靠、经济运行起着决定的作用。
本设计针对110kV降压变电站进行电气部分设计，电压等级110kV/35kV/10kV；设计内容包括：变压器台数和容量的选择、主接线的选择、短路电流的计算、主要电器设备的选择和校验、继电保护及变电站防雷等。
设计中依据《电力工程设计手册，电气一次部分》、《发电厂、变电站电气部分》，《电力继电保护原理》《中小型变电所实用设计手册》《电气设备设计计算手册》 《交流高压断路器订货技术条件》、《交流电气装置的过电压保护和绝缘配合》、《高压配电装置设计技术规程》等国家和电力行业有关110kV变电所设计、标准、规程、规范及国家有关安全、环保等强制性标准。 关键词：降压 变电站 电气 设计
目 录
第一章 绪 论 ······················································································ 1
选题背景 ············································································· 1 选题意义 ············································································· 1 变电站发展概况 ···································································· 1 设计原始资料 ······································································· 2 变电站的出线 ····································································· 2 负荷情况 ··········································································· 2 线路长度 ··········································································· 2
第一节 第二节 第三节 第四节
一、 二、 三、
第二章
电气主接线设计及短路电流计算 ···················································· 3
电气主接线设计及主变压器容量选择 ········································· 3 电气主接线方案初选 ··························································· 3 主接线方案比较·································································· 3 主变压器的选择·································································· 4 站用变压器的选择 ······························································ 5 短路电流计算 ······································································· 5 短路电流的计算目的 ··························································· 5 短路电流计算点的确定 ························································ 6 计算步骤 ··········································································· 6 变压器、线路及电抗器的参数计算 ········································· 6 系统网络化简 ····································································· 8 110kV母线短路点K1的短路计算 ··········································· 8 35KV母线短路点K2的短路计算 ·········································· 10 10KV母线短路点K3的短路计算··········································· 11 10KV出线短路点K4的短路计算 ·········································· 12
第一节
一、 二、 三、 四、 第二节
一、 二、 三、 四、 五、 六、 七、 八、 九、
第三章
电气主设备的选择及校验 ···························································· 14
选择原则及规定 ··································································· 14
第一节
一、 二、 三、 第二节
一、 二、 三、 四、 五、 六、 七、
第四章
一般原则 ·········································································· 14 校核电器的基本使用条件 ···················································· 14 各回路最大持续工作电流 ···················································· 14 主设备选择及校验 ································································ 15 断路器的选择及校验 ·························································· 15 隔离开关的选择及校验 ······················································· 18 电流互感器的选择及校验 ···················································· 21 电压互感器的选择 ····························································· 26 避雷器的选择及检验 ·························································· 28 母线的选择及校验 ····························································· 30 熔断器的选择 ···································································· 32
主变保护整定计算及防雷接地计算 ················································ 34
变压器继电保护 ··································································· 34 变压器差动保护计算 ·························································· 34 变压器过流保护及过负荷保护计算 ········································ 36 防雷接地计算 ······································································ 37 防雷计算 ·········································································· 37 接地计算 ·········································································· 39
第一节
一、 二、 第二节
一、 二、
总 结 ·································································································· 41 致 谢 ··········································································· 错误！未定义书签。 参 考 文 献 ······················································································ 42 附录A 主接线方案图 ············································································· 43 附录B 系统正序等值图 ·········································································· 45 附录C 设备选择参照图 ·········································································· 46 附录D 短路电流计算结果表 ···································································· 47 附录E 变电所主体设备型号一览表 ··························································· 48
第一章
第一节 选题背景
绪 论
电力已成为人类历史发展的主要动力资源，要科学合理的使用及分配电力，必须从工程的设计来提高电力系统的安全性、可靠性和运行效率，从而达到降低成本，提高经济效益的目的。变电站是电力系统配电传输不可缺少的重要组成部分，它直接影响整个电力网络的安全和电力运行的经济成本，是联系发电厂和用户的中间环节，起着变换和分配电能的作用。电气主接线是发电厂变电所电气部分的主体，电气主接线的拟定直接关系着全厂（所）电气设备的选择、配电装置的布置、继电保护和自动装置方式的确定，对电力系统的安全、可靠、经济运行起着决定的作用。
目前，110KV、35KV常规变电站在城农网中仍占有较大的比重，其一次、二次设备都比较落后，继电保护装置多为电磁式继电器组合而成，一般只具有当地控制功能，多为有人值班运行方式。随着电网运行自动化系统的提高,变电站综合自动化系统发挥着越来越强大的作用,少人或无人值守变电站将成为今后变电运行的主流方式，对原有电站及新建电站实现无人值守势在必行。对设计人员来讲，我们只有不断提高自身素质，才能跟得上电力系统的飞速发展，为电力事业的兴盛尽一点微薄之力。
第二节 选题意义
变电站是电力系统中变换电压、接受和分配电能、控制电力的流向和调整电压的电力设施，它通过其变压器将各级电压的电网联系起来。变电站起变换电压作用的设备是变压器，除此之外，变电站的设备还有开闭电路的开关设备，汇集电流的母线，计量和控制用互感器、仪表、继电保护装置和防雷保护装置、调度通信装置等，有的变电站还有无功补偿设备。
本设计针对变电站进行设计，设计内容包括：变压器台数和容量的选择、主接线的选择、短路电流的计算、主要电器设备的选择和校验、继电保护及变电站防雷等。通过对110KV降压变电所电气部分的设计，使我明白其目的在于使我们通过这次毕业设计，能够得到各方面的充分训练，结合毕业设计任务加深了对所学知识内在联系的理解，并能灵活的运用。
第三节 变电站发展概况
随着计算机技术的飞速发展，微型计算机技术在电力系统中得到了越来越广泛的应用，它集变电站中的控制、保护、测量、中央信号、故障录波等功能于一身，替代了原常规的突出式和插件式电磁保护、晶体管保护、集成电路保护。常规控制、保护
装置已逐步从电力系统中退出，取而代之的则是这种新型的微机监控方式，它运用了自动控制技术、微机及网络通信技术，经过功能的重新组合和优化设计，组成计算机的软硬件设备代替人工,利用变电站中的远动终端设备来完成对站中设备的遥信、遥测、遥调、遥控即四遥功能。这就为实现变电站无人值守提供了前提条件。变电站、所综合自动化和无人值守是当今电网调度自动化领域中热门的话题，在当今城、农网建设改造中正被广泛采用。
第四节 设计原始资料
一、 变电站的出线
变电站的电压等级为110kV/35kV/10kV，设两台主变，变电站最终规模的进出线回路数为：
110kV：2回（双电源进线） 35kV：6回（终端用户） 10kV： 12回（终端用户）
二、 负荷情况
35kV、10kV负荷情况见下表。
表1-1 负荷情况表
电压等级 负荷级别 I 35kV II III I 10kV 站用电 最大负荷（MW） 8 8 4 7 5 4 0.6 合计负荷（MW） 20 II III I 16 0.6 三、 线路长度
110kV： 架空线，170公里 35kV： 架空线，76 公里 10kV： 架空线，27 公里