阻抗匹配平衡变压器差动保护动作方程与整定

Operational Equation and Setting of Differential Protection for Impedance-Matching Balance Transformer

用原边相电流构成阻抗匹配平衡变压器的差动保护,当阻抗匹配系数KZ≠3 +1时产生固有的不平衡电流,易引起误动作.按变压器原边相电流差构成电流差动保护解决上述问题.针对3段折线的动作特性,给出了阻抗匹配平衡变压器差动保护整定计算原则与公式,其中考虑了正常运行的不平衡电流、电流互感器饱和及最大励磁涌流对差动保护动作的影响.

If impedance matching coefficient Kz does not equal root 3 + 1 for an impedance-matching balance transformer with differential protection based on phase current on primary side, there is inherent differential current, and may result in mal-operation. This problem was solved by taking the differences in phase current on primary side as the parameters to form the operational equations. Setting rules were discussed and formulae were derived for impedance-matching balance transformers based on the 3-slope operation characteristic, where the effects of normal mismatch current, current-transformer saturation and inrush current on differential current protection were taken into consideration.