Study On The Impedance Measurement Method Based On The Adaptive Residual Current Compensation

A new residual current compensation method based on the magnitude of current of each phase that has the clear phase selection ability is presented in this paper. The residual current is compensated in an adaptive manner. The characteristic of the faulted phase is the same as the traditional method with this new compensation method. The performance of the healthy phase has been improved by this new method. A new scheme in which the distance relay is designed only for the phase-to-ground is presented in this paper. If only one phase -to-ground relay operates, the operated phase is tripped in a single-pole tripping scheme; otherwise, the tree phase of the protected line is tripped.The operation characteristic of the new relay is analyzed in theory and verified by the simulation tests. The new relay operates with clear selectivity and high operation speed and can satisfy the demand of the protection for the EHV transmission line. The performance of the fault component impedance relay has been improved and the misoperaion of the healthy phase under cross-country fault and close-in fault have been avoided.