小接地系统4PT方式的二次电压分析与建模

摘要

The 4PT connection in the isolated neutral system is an effective measure for eliminating ferromagnetic resonance.This paper analyzes the features of secondary voltage in the normal and faulty 4PT cases.Focusing on frequent reverse polarity of neutral point PT,it summarizes the distribution rule of secondary voltage on the basis of the change of the ratio between the impedances of phase PT and neutral point PT.Finally,a 4PT simulation model is built up on the base of PACAD/EMTDC,and simulation experiments are made in different working conditions.Correctness of theoretical calculation is verified in site operational examples,thus providing valuable experiences for people working on the operation and maintenance of substations in the aspect of 4PT.%中性点不接地系统中4PT接线方式是消除铁磁谐振的一项有效措施.系统分析了4PT方式下正常和故障态时的二次电压特征.之后针对现场经常出现的中性点PT极性反接的问题,总结出随着相PT和中性点PT阻抗比值的变化,二次测量电压的分布规律.最后,建立了基于PSCAD/EMTDC的4PT仿真模型,进行多种工况下的仿真;并结合现场运行实例,验证了理论计算的正确性.的工作给变电所运行和检修人员提供了4PT方式的运行维护提供了参考经验.