【摘要】 利用变压器在空投或故障情况下磁通对称特性来判别励磁涌流和故障电流是基于变压器的数学模型而得,较为真实地反映了变压器的运行工况。本文从变压器磁通和电流的非线性关系出发,分别找出变压器在空投、正常运行以及内部故障时磁通的变化规律,取一个周波内磁通对电流的变化率前后半波的对称度来反应磁通的这种变化(对称与否)。对称度大小作为区分励磁涌流和故障电流的判据,具有较高的可靠性和灵敏度,通过试验和仿真证明该方法可以有效地区分励磁涌流和故障电流,具有较高的实用性。更多还原

【Abstract】 Flux symmetry character is used to distinguish inrush current and fault current when a transformer is switched on and energized or fault occurs, which is deducted by the transformer mathematical model and truly responses the running status of transformer. In the paper, according to the nonlinear relation of flux to current, the variational rule of the flux can be founded out when a transformer is switched on or running or faults occurring, and the rule (symmetry or not ) can be expressed with the ratio of flux to current of fore-and-aft half cycle in one cycle data window. So the symmetry degree is very reliable and sensitive to be used to distinguish rush current and fault current. It is very practical to use the method to judge inrush current in transformer differential protection.更多还原