A Special Protection Scheme for Transmission Lines based on Wide Area Monitoring System

The utilization of phasor measurement units (PMUs) with protective relays is rapidly increasing in the existing power transmission networks for reliable monitoring, control and protection of complex power system. Thus, it is feasible to develop an effective primary and backup protection scheme for transmission lines by utilizing the information from PMU-cum-Relays. Regarding the conventional relays, it is observed that its operation is severely affected with the presence of events like power swings, load encroachment etc. In this paper, authors propose to utilize wide area monitoring system for backup protection of transmission lines using proposed phasor data concentrator (PDC) index, which is calculated at PDC using the measured frequencies from different PMUs. As the backup protection scheme is centrally executed at PDC, the proposed scheme do not require the coordination time, but do involve communication delays associated with the network. The effectiveness of proposed special protection scheme has been tested and validated on reduced NEREB 29-bus Indian power system with distributed generation sources using SINCAL and MATLAB softwares. The simulation results reveal that the proposed special protection scheme can enhance the protection strategy of transmission lines in smart electric grid.