Ferro-resonance over-voltage and power frequency over-voltage on the neutrals of 220kV power transformer and corresponding protection strategy
In order to limit short-circuit current and satisfy the need of relay setting,only part of the 220kV power transformer is grounded,so on the neutrals of ungrounded transformers will appear the over-voltage. Currently the value of over-voltage on transformer neutral point and the corresponding protection strategy is based on theoretical formula,this article use the PSCAD/EMTDC software to calculate the over-voltage on the neutral point of 4 ungrounded power transformers in Chongqing 220kV power grid,the result shows that the power frequency transient over-voltage on the neutrals may reach 178kV,If the single-phase grounding fault occurs in ungrounded power system,the power frequency over-voltage on the neutrals will be more serious and rise to 138.6kV. Non-full phase operation may cause serious ferro-resonance over-voltage on the neutrals of no-load transformer,which may last for seconds and may rise to 723.7kV,causing serious threat to the transformer neutrals and line-side equipment. The article also studies the gap parameter which should be taken on the neutrals of 220kV transformers at the end.
neutral point power transformer arrester gap power frequency over-voltage lightning over-voltage
YU Hua-peng CHEN Shui-ming Yu Hong-qiao YANG Peng-cheng YIN Hua WU Gaolin
State Key Lab of Control and Simulation of Power Systems and Generation Equipments (Dept.of Electric Chongqing Electric Power Research Institute,Chongqing 401123,China
国际会议
南京
英文
1349-1354
2010-09-13（万方平台首次上网日期，不代表论文的发表时间）