Modern numerical protection schemes with phase Comparison

摘要

Numerical phase comparison protection overcomes the problems faced on the long EHV transmission system by providing dynamic compensation of charging current at all times thus providing stability during external fault conditions. With the implementation of impedance starters complimenting current and voltage starters, enhances the sensitivity thus enabling the gap detection algorithm, which is based on the modulation current using the positive and the negative sequence component current. The amplification of the negative sequence current based on load current provides reliability of the protection to detect high resistance earth fault even in long transmission lines. The numerical phase comparison protection provides flexibility to user by adapt settings according to different system configurations.