PMU based adaptive zone settingsof distance relays for protection ofmulti-terminal transmission lines

This paper proposes Phasor Measurement Unit (PMU) based adaptive zone settings of distance relays (PAZSD)methodology for protection of multi-terminal transmission lines (MTL). The PAZSD methodology employs currentcoefficients to adjust the zone settings of the relays during infeed situation. These coefficients are calculated inphasor data concentrator (PDC) at system protection center (SPC) using the current phasors obtained from PMUs.The functioning of the distance relays during infeed condition with and without the proposed methodology hasbeen illustrated through a four-bus model implemented in PSCAD/EMTDC environment. Further, the performanceof the proposed methodology has been validated in real-time, on a laboratory prototype of Extra High Voltagemulti-terminal transmission lines (EHV MTL). The phasors are estimated in PMUs using NI cRIO-9063 chassisembedded with data acquisition sensors in conjunction with LabVIEW software. The simulation and hardwareresults prove the efficacy of the proposed methodology in enhancing the performance and reliability ofconventional distance protection system in real-time EHV MTLs.