电网技术2011，Vol.35Issue(1)：146-151,6.
220kV变压器中性点经小电抗接地方式
Neutral Grounding via Small Reactance for 220 kV Power Transformers
于化鹏 1陈水明 1杨鹏程 1印华 2崔婷2
作者信息
- 1. 电力系统及发电设备控制和仿真国家重点实验室(清华大学电机系),北京市,海淀区,100084
- 2. 重庆电力科学试验研究院,重庆市,渝北区,401123
- 折叠
摘要
Abstract
To suppress short-circuit and meet the demand of the setting of protective relaying, only part of neutral points of power transformers of 220 kV power systems in China are grounded, and this grounding mode leads to overvoltage appeared at the neutral points of non-grounded power trensformers. In 220 kV power system adopting such a neutral grounding mode, the neutral overvoltage may rise to phase voltage when single-phase earth fault occurs while the grounding is in failure. Although arrestors and gap can be used to suppress neutral overvoltage, however due to the dispersity of gap discharging the malfunction of the gap may occur and the insulation coordination of gaps with arrestors may disorder.For this reason a model of 220 kV power system in Chongqing area is built and neutral overvoltage and short-circuit current are computed by PSCAD/EMTDC software when the neutral of 220 kV power transformer is grounded via an additional small reactance. Calculation results show that under neutral connected in series with small reactance, the neutral overvoltage evidently reduces and the grounding failure no more occurs, and the neutral overvoltage as high as phase voltage no more appears, so it is enough to install arrestors to the neutrals and it is not necessary to configure gaps for neutrals. Besides, after the small reactance is added to neutral the single-phase short-circuit current flowing through transformer winding will be decreased, thus the damage of transformer can be prevented. Finally, the influences of adding small reactance to neutral on protective relaying are analyzed.关键词
中性点/变压器/小电抗/短路电流/工频过电压Key words
neutral point/ power transformer/ small reactance/ short-circuit current/ power frequency overvoltage分类
动力与电气工程引用本文复制引用
于化鹏,陈水明,杨鹏程,印华,崔婷..220kV变压器中性点经小电抗接地方式[J].电网技术,2011,35(1):146-151,6.
