电网技术Issue(4)：1074-1082,9.
多个500 kV站点自耦变中性点加装小电抗对零序电量叠加影响的研究
Influences of Adding Small Reactances to Neutral Points of Autotransformers in Multiple 500 kV Substations on Superposition of Zero-Sequence Electrical Quantities
摘要
Abstract
To suppress short-circuit current in power grid, it is an effective measure to add small reactances to neutral points of 500 kV autotransformers. After adding small reactances to neutral points of 500 kV autotransformers, zero-sequence parameters of power grid are changed, so the influences of this measure on fault electrical quantities during unsymmetrical earth fault occurred in transmission line cannot be neglected. Based on 500 kV autotransformers a ring equivalent model of a power grid containing three 500 kV substations is built, and actual on-site parameters of Guangdong power grid is utilized in the simulation. The influences on relative variations of zero-sequence electrical parameters are quantitatively calculated under different positions, where the fault occurs, before and after adding small reactance to neutral point of autotransformer in single substation. Calculation results show that when earth fault occurs at the outlet of transmission line, the affection of adding small reactance on zero-sequence parameters is most serious. The influences of adding small reactance to neutral point of autotransformer on related protective relayings are analyzed, and it is pointed out to meet the demand on protection sensitivity the zero-sequence current protection of neutral points of autotransformers is to be anew set. For the circumstance that small reactances are added to neutral points of autotransformers in all substations at the same time, theoretical analysis shows that there is superposition effect of zero-sequence electrical parameters under various situation of adding small reactances, and such a conclusion is verified by simulation results of actual power grid.关键词
中性点接地/零序电流/接地故障/叠加效应/继电保护Key words
neutral grounding/zero-sequence current/earth fault/superposition effect/protective relaying分类
信息技术与安全科学引用本文复制引用
李晓华,张波,傅龙辉,谢金泉,晏寒婷,罗龙波,邱建..多个500 kV站点自耦变中性点加装小电抗对零序电量叠加影响的研究[J].电网技术,2013,(4):1074-1082,9.基金项目
国家自然科学基金资助项目(50807017) （50807017）
华南理工大学中央高校基本科研业务费专项资金资助(2012ZZ0024) （2012ZZ0024）
