The simulation research of transverse differential protection based on impedance ratio for double circuit lines on the same tower

Conventional current transverse differential protection has shortages when being applied to high-voltage and asymmetry power systems, such as low sensitivity and long successive operating zone. A new transverse differential protection scheme based on the measurement impedance ratio is proposed. The proposed scheme is unaffected by system impedance to a large extent, using the ratio of the sum and difference impedance of respective transmission line can build the criterion of the protection. PSCAD/EMTDC simulation shows that the fault resistance almost does not affect the proposed protection. Compared with traditional current transverse differential protection the suggested protection can decrease the successive operating zone obviously. And the proposed integrated protection scheme is simple, reliable, and easy to realize.