变压器参数不对称对后备阻抗保护的影响研究

根据某500 kV主变单相替换工程实例,从理论分析与基于PSCAD/EMTDC模型研究替换后,在正常及故障情况下因三相短路电压百分比不一致对后备阻抗保护的影响,得出在满足变压器并列运行的条件下,主变单相替换后由于三相参数不对称对接地阻抗元件的影响要大于相间阻抗元件的影响,但都不会使阻抗保护产生误动作或者拒动作.同时也说明了变压器运行时三相短路电压百分比允许一定程度的不对称性,为进一步研究主变单相替换的可行性提供了理论参考.

Influence of Transformer Parameter Asymmetry on Backup Impedance Protection

According to the practical project on 500 kV main transformer of replacing single phase,the impact on backup impedance protection under normal and fault circumstances which is caused by asymmetric of three phase short-circuit voltage percentage is studied from Theoretical analysis and PSCAD/EMTDC simulation.The conclusion can be drawled that impact on grounding impedance element is greater than interphase Impedance element because of three phase parameter asymmetry after single phase replacement,but it will never make the impedance protection misoperation or failure action.Also shows the three phase short-circuit voltage percentage of transformer can withstand a certain degree of asymmetry,provide a theoretic reference for further study on feasibility of single phase replacement