Local Supervision of Distance Relay Using Rodrick-Prescott Filter

Distance relays are vulnerable to trip on power swing. This unwanted tripping, sometimes, initiates uncontrolled system separation due to cascade tripping of transmission lines. This may even result in a catastrophic failure of the grid. Hence, distance relays must be temporarily blocked from the operation during a power swing. In this paper, we propose a predictive analytics using local substation voltage and current phasors for blocking distance relay during power swing. Unlike existing schemes, it can evaluate the time to encroachment as well as time to Out of Step condition. This scheme is setting free and independent of network parameters. It does not require any transient stability studies. It can even unblock the relay on a fault during power swing using extended Hodrick-Prescott (H-P) filter. Thus, it is a comprehensive scheme which provides blocking as well as unblocking to a distance relay.