自适应变压器励磁涌流判据研究

摘要

The criterion of transformer magnetizing inrush current based on positive sequence component of differential current harmonics can identify inrush and internal fault effectively. In order to further improve the blocking reliability in magnetizing inrush current cases and operation speed in internal fault cases of differential protection, terminal voltage and its mutation in positive sequence component of fundamental harmonic are analyzed respectively in magnetizing inrush cases and internal fault cases. According to their different characteristics, an adaptive control factor Q is determined, which is added to the magnetizing current criterion based on positive sequence of differential current harmonics, then a new adaptive criterion of transformer magnetizing inrush current is proposed. A large number of EMTP simulations and dynamic simulation experiments show that the new criterion can automatically decrease the threshold setting of restraint in inrush cases, so the reliability of inrush blocking is improved, and it can also automatically increase the threshold setting of restraint in internal fault cases, so the operation speed during internal fault conditions is accelerated.%基于差流谐波正序分量的变压器励磁涌流判据能够有效识别励磁涌流和内部故障。为了进一步提高差动保护的励磁涌流闭锁可靠性和内部故障动作快速性，分析了变压器端电压及其基波正序分量突变量在励磁涌流和内部故障时的不同特征，由此确定了自适应控制因子Q，并将Q加入到差流谐波正序分量的励磁涌流判据中，进而提出了一种自适应变压器励磁涌流新判据。大量EMTP仿真及动模实验表明：新判据能够在励磁涌流时自动降低涌流制动定值，提高涌流的闭锁可靠性；在内部故障时自动升高涌流制动定值，提高区内故障时保护的动作速度。