变压器励磁涌流和内部故障电流识别研究

Research on Discriminating Inrush Current and Internal Fault Current in Transformer Protection

针对变压器差动保护无法准确识别励磁涌流和内部故障电流的难题,在瞬时无功功率理论基础上,提出一种通过比较变压器两侧差瞬时有功和差瞬时无功直流分量比值变化情况来识别励磁涌流和内部故障电流的新原理。该原理避开变压器内部复杂的磁链关系,从能量守恒的角度揭示了变压器励磁涌流和内部故障电流本质上的不同。MATLAB仿真结果表明:新原理简单易行,识别效果显著。

The correct identification of the inrush current and the internal fault has been a difficult issue in the transformer differential protection. Based on the instantaneous reactive power theory, a new principle compared the variation of DC component ratio of active power to reactive power of transformer differential power is prop- osed to identify the inrush current and the internal fault current. This principle avoids the transformer interior complex flux linkage relations, and reveals essential difference between the inrush current and the internal cur- rent from the viewpoint of energy conservation law. The MATLAB simulation results show that the new princi- ple is simple and feasible, and it has a clear identification ability.