过电流保护在变压器合闸过程中的自适应策略

变压器铁磁材料的激磁特性呈现非线性,这将导致在变压器合闸过程中产生励磁涌流现象。过电流保护往往反映单一的电流幅值特征而动作,当变压器合闸过程发生时,励磁涌流及邻近区域内的穿越电流均可能导致相关联的过电流保护误动。从序分量的角度出发,构建了一个可通过标志函数的大小和突变,区分故障与涌流的序分量标志函数。通过PSCAD/EMTDC仿真表明,该标志函数能够充分反映电网结构的变化,有效区分变压器励磁涌流和故障。将该标志函数应用于过电流保护上可以减小励磁涌流的影响。

Adaptive strategy for overcurrent protection in process of transformer closing

The excitation characteristics of transformer ferromagnetic material present nonlinearity, which leads to inrush current phenomenon in the process of transformer closing. Overcurrent protection often acts reflecting single current amplitude characteristic. When transformer closing, inrush current and through current in the neighboring region may cause correlative overcurrent protection malfunctions. This paper, from the view of sequence components, constructs a mark function. The mark function can distinguish fault and inrush current by its value and sudden change. The simulation by PSCAD/EMTDC tool shows that this function can reflect the changes of power network structure fully, and the function can distinguish transformer inrush current and fault effectively. The application of mark function to current protections can reduce the effect of inrush current on overcurrent protections.