一种变压器励磁涌流的新型鉴别方法

A New Identification Method for Inrush Flow of Transformer

目的电力变压器的励磁涌流作为一种非正常电流,会影响电能质量和损害电子设备寿命,对于变压器乃至电力系统都会造成较大的冲击。因此,励磁涌流与内部故障电流的准确识别一直是电力变压器差动保护的关键问题。方法从励磁涌流产生机理和常见涌流识别方法入手,分析其特征,将变压器磁通中的直流分量和两侧瞬时有功功率提取出来,获得一种新的励磁涌流判据方法。结果将该方法应用在变压器模型中,并且将模型中的参数进行修改,在不同合闸角下进行仿真,对比励磁涌流的数值。同时对比正常运行状态及不同程度的相间短路故障状态的仿真结果,证明该判据可以快速而准确地识别,且留有充足的整定裕量。结论通过MATLAB仿真证明,该方法是可行有效的,且在变压器保护装置的可靠性、灵敏性方面都具有一定的优势。

Objective As an abnormal current,the inrush current of power transformer will affect the power quality and damage the life of electronic equipment.It will cause great impact on transformer and even power system.Therefore,the accurate identification of inrush current and internal fault current is always the key problem of power transformer differential protection.Methods Starting from the mechanism of inrush current and the common methods of inrush current identification,the characteristics of the transformer were analyzed.The DC component in the flux and the instantaneous active power on both sides were extracted,and a new criterion of inrush current was obtained.Results The method was applied to the transformer model,and the parameters in the model were modified.The simulation was carried out at different closing angles to compare the values of inrush current.At the same time,the simulation results of normal operation state and different degree of phase-to-phase short-circuit fault state were compared,which proved that the criterion can identify quickly and accurately,and it has sufficient setting margin.Conclusion The simulation with MATLAB showed that the method is feasible and effective,and has certain advantages in reliability and sensitivity of transformer protection device.