A Performance Analysis of Transmission Line Differential Protection

This work accomplishes a comparative analysis between two transmission line differential protection methodologies available in commercial relays: percentage and alpha-plane differential protections. In order to verify the operation limits of the protections, several internal and external faults were simulated considering variations of the fault location, fault inception angle, fault impedance, and TC saturation. The alpha-plane method presented was the most accurate and fastest since the sequence units were not influenced by the fault impedance.