Scott变压器差动保护电流互感器接线方式分析

在自耦变压器(auto-transformer,AT)供电方式变电所改造中,斯科特(Scott)牵引变压器差动保护采用微机保护。根据Scott牵引变压器的电流变换关系,得出了三种差动保护平衡方程。三个方案都能保证差动保护在各种情况下正确动作。基于保护平衡方程结构形式,从励磁涌流对保护影响、保护的灵敏性和微机保护整定方面比较分析了三种电流互感器接线的优劣。适应于当今微机保护要求,方案三在确保正确动作情况下可以分相制动,在保护可靠性、灵敏度方面的性能更优,并推荐采用按相整定定值方式。

Analysis of Current Transformer Wiring Scheme for Differential Protection on Scott Transformer

During the reconstruction of the substation with auto-transformer(AT) power supply mode,the microprocessor was applied into the differential protection for Scott traction transformer.According to the current transformation relation of the Scott traction transformer,three differectial protective equations were obtained,which proved to be feasible under all possible situations.Based on the balanced equations,three kinds of current transformer wiring schemes are compared from three aspects that are the influence of inrush currents,sensitivity of protection and setting of the microprocessor based protection.The third scheme can operate by phase,which has better reliability and sensitivity and is more applicable for microprocessor based protection.And it is recommended that the setting should be set by phase respectively.