-110kV变电站电气设备选择

1目录摘要·································································································2关键词······························································································21设计内容························································································22原始资料························································································23电气主接线选择···············································································33.1概述···························································································33.2主接线设计··················································································33.2.1110KV电气主接线设计································································33.2.235KV电气主接线设计··································································53.2.310KV电气主接线设计··································································64.变压器选择·····················································································74.1负荷计算·····················································································74.2主变压器选择···············································································84.3站用变压器选择··········································································105短路电流计算················································································125.1概述·························································································125.2短路电流计算的目的····································································125.3短路电流计算的一般规定······························································125.4短路电流的计算过程····································································136电气设备的选择与校验····································································186.1电气设备选择的一般条件······························································186.2最大长期工作电流·······································································206.3高压断路器选择与校验·································································226.4隔离开关的选择与校验·································································246.5互感器的选择与校验····································································266.6母线选择与校验··········································································296.7各主要电气设备选择一览表···························································33附录:Ⅰ··························································································34参考文献·························································································352110kV变电站电气设备选择梅杰摘要：本文首先根据任务书上所给系统与线路及所有负荷的参数，分析负荷发展趋势。从负荷增长方面阐明了建站的必要性，然后通过对拟建变电站的概括以及出线方向来考虑，并通过对负荷资料的分析，安全，经济及可靠性方面考虑，确定了110kV，35kV，10kV以及站用电的主接线，然后又通过负荷计算及供电范围确定了主变压器台数，容量及型号，同时也确定了站用变压器的容量及型号，最后，根据最大持续工作电流及短路计算的计算结果，对高压熔断器，隔离开关，母线，电压互感器，电流互感器进行了选型，从而完成了110kV变电站电气设备的选择。关键词：变电站变压器接线1设计内容1.进行负荷计算及分析；2.电气主接线的设计；3．主变压器的选择及设备选型和校验。2原始资料1.环境条件:所址地区地势平坦，起初平均海拔高度低于100米，该地区气候平均气温17摄氏度，最高气温40摄氏度，最低气温-5摄氏度。2.建站规模（1）变电站类型：110kV变电工程（2）主变台数：一期投入两台（3）本变电站的电压等级为110kV/35kV/10kV（4）各电压等级出线回数及最大负荷110kV出线4回，2回备用，最大负荷68MVA35kV出现10回，2回备用,最大负荷27MVA10kV出现20回，3回备用,最大负荷38MVA3本变电站计算站用最大负荷为0.16MVA3.变电站负荷情况本变电站由两个系统供电，系统S1为600MVA，容抗为0.38,线长30000M系统S2为800MVA，容抗为0.45,线长20000M.4.电气主接线110kV、35kV、10kV均采用单母线分段（带旁路）接线，并考虑设置熔冰措施。3电气主接线选择3.1概述电气主接线是发电厂、变电所电气设计的重要部分，也是构成电力系统的重要环节。主接线的确定对电力系统整体及发电厂、变电所本身运行的可靠性、灵活性和经济性密切相关，并且对电气设备选择、配电装置布置、继电保护和控制方式的拟定有较大影响。因此，必须处理好各方面的关系，全面分析有关影响因素，通过技术经济比较，合理确定主接线方案，决定于电压等级和出线回路数。3.2主接线设计3.2.1110kV电气主接线设计《35～110KV变电所设计规范》规定35～110kV线路为两回及以下时，宜采用桥形、线路变压器组或线路分支接线。超过两回时，宜采用扩大桥形、单母线或分段单母线的接线。110kV线路为6回及以上时，宜采用双母线接线。本变电站110kV线路有4回，可选择单母线或分段单母线两种接线。方案I：采用单母线接线4单母线接线优点：接线简单清晰、设备少操作方便、便于扩建和采用成套配电装置。缺点：不够灵活可靠，任一元件（母线及母线隔离开关等）故障或检修，均需使整个配电装置停电。方案II：采用单母线分段接线单母线分段接线优点：（1）用断路器把母线分段后，对重要用户可以从不同段引出两个回路，有两个电源供电。（2）当一段母线发生故障，分段断路器自动将故障段切除，保证正常段母线不间断供电和不致使重要用户停电。（3）占地少、设备少。缺点：（1）当一段母线或母线隔离开关故或检修时，该段母线的回路都要在检修期间内停电。（2）当出线为双回路时，常使架空线路出线交叉跨越。鉴于此站为地区变电站应具有较高的可靠性和灵活性。经综合分析，决定选第Ⅱ种方案为设计的最终方案。，决定采用单母线分段接线53.2.235kV电气主接线设计《35～110KV变电所设计规范》规定35～110kV线路为两回及以下时，宜采用桥形、线路变压器组或线路分支接线。超过两回时，宜采用扩大桥形、单母线或分段单母线的接线。35～63kV线路为8回及以上时，亦可采用双母线接线或单母线分段带旁路母线接线。110kV线路为6回及以上时，宜采用双母线接线。本变电站35kV线路有10回，可采用双母线接线或单母线分段带旁路母线接线。方案I：采用单母线分段带旁路母线接线单母线分段带旁路母线接线优点：简单清晰、操作方便、易于发展，旁路断路器还可以代替出线断路器，进行不停电检修出线断路器，保证重要用户供电，设备少、投资小，用母线分段断路器兼作旁路断路器节省投资。缺点：可靠性、灵活性差。方案II：采用双母线接线6双母线接线优点：供电可靠、调度灵活、扩建方便、便于试验、易误操作。缺点：设备多、配电装置复杂，投资和占地面大。经比较两种方案都具有易扩建这一特性。虽然方案Ⅰ可靠性、灵活性不如方案Ⅱ，但其具有良好的经济性。鉴于此电压等级不高，可选用投资小的方案Ⅰ。3.2.310kV电气主接线设计《35～110KV变电所设计规范》规定当变电所装有两台主变压器时，6～10kV侧宜采用分段单母线。线路为12回及以上时，亦可采用双母线。当不允许停电检修断路器时，可设置旁路设施。本变电站10kV线路有20回，可采用双母线接线或单母线分段接线方案I：采用双母线接线双母线接线优点：供电可靠、调度灵活、扩建方便、便于试验、易误操作。7缺点：设备多、配电装置复杂，投资和占地面大。方案II：采用单母线分段接线单母线分段接线优点：（1）用断路器把母线分段后，对重要用户可以从不同段引出两个回路，有两个电源供电。（2）当一段母线发生故障，分段断路器自动将故障段切除，保证正常段母线不间断供电和不致使重要用户停电。（3）占地少、设备少。缺点：（1）当一段母线或母线隔离开关故或检修时，该段母线的回路都要在检修期间内停电。（2）当出线为双回路时，常使架空线路出线交叉跨越。经过比较方案Ⅱ在经济性上比方案Ⅰ好，且调度灵活也可保证供电的可靠性。所以选用方案Ⅱ。4.变压器选择4.1负荷计算要选择主变压器和站用变压器的容量，确定变压器各出线侧的最大持续工作电流。首先必须要计算各侧的负荷，包括站用电负荷（动力负荷和照明负荷）、10kVφ负荷、35kV负荷和110kV侧负荷。8由公式%1cos1nitcpKS式中sC——某电压等级的计算负荷kt——同时系数（35kV