接地变兼站用变短路阻抗基准侧的选取与保护  

Selection and Protection of Short Circuit Impedance Reference Side of GroundingTransformer and Substation Transformer

作　　者：辛志磊 XIN Zhilei(Beijing Xinya Shengchuang Electrical Technology Co.,Ltd.,Beijing,100089,China)

机构地区：[1]北京新亚盛创电气技术有限公司,北京100089

出　　处：《水电科技》2020年第5期94-97,共4页Hydroelectric Science & Tecnology

摘　　要：从本质上介绍了不接地系统到电阻或消弧线圈接地系统的演变过程;引出了接地变和接地变兼站用变的概念,解释了接地变、接地变兼站用变的构造和原理;遵照国家标准,并借鉴项目经验,总结了通过接地变兼站用变铭牌参数确定短路阻抗选取基准侧的方法,并且结合实例给出了详细的解释推导,奠定了接地变兼站用变的短路电流计算,继电保护整定计算的计算基础;基于确定基准侧后的短路电流计算,分析了接地变兼站用变与普通接地变的速断保护整定计算的差异,分别从躲过变压器低压侧出口三相短路,躲过变压器空载合闸与外部短路故障切除电压恢复可能出现的最大励磁涌流,躲过区外单相接地时流过接地变压器的最大故障相电流,并保证接地变压器电源侧在最小方式下两相短路时有足够灵敏度四项原则分析计算了接地变兼站用变的速断保护整定值;区分了接地变兼站用变与普通接地变的整定原则,总结了相关实践经验。The evolution process from ungrounded system to resistance or extinction coil grounding system is introduced in essence.The concepts of grounding transformer and grounding transformer combined with station transformer are introduced and the structure and principle of grounding transformer and station transformer are explained.According to national standards and referring to project experience,the method of determining short-circuit impedance and selecting reference side through nameplate parameters of grounding transformer and station transformer is summarized based on the calculation of short-circuit current after determining the reference side and the differences of quick break protection setting calculation between the grounding transformer and the common grounding transformer are analyzed,which can avoid the three-phase short-circuit at the outlet of the low-voltage side of the transformer.The maximum inrush current can be recovered by the voltage of no-load closing and external short-circuit fault clearing,avoiding the maximum fault phase current flowing through the grounding transformer when the single-phase grounding outside the zone is avoided and sufficient sensitivity is ensured when two-phase short-circuit occurs at the power supply side of the grounding transformer under the minimum mode.The setting value of quick break protection of grounding transformer and station transformer is analyzed and calculated,the grounding is distinguished and the setting principle of substation transformer and common grounding transformer is summarized.

关 键 词：不接地系统 消弧线圈接地 低电阻接地 接地变兼站用变 短路阻抗 速断保护 

分 类 号：TM77[电气工程—电力系统及自动化]