Impact of UPFC on alpha plane line current differential protection

Abstract

This paper presents an impact on alpha plane characteristics of line current differential protection in presence of unified power flow controller (UPFC). UPFC is a versatile device with the ability to regulate bus voltage and control power flow of the transmission line independently and simultaneously; hence, it has an impact on the current signals received at the relay location. With the advancement in synchrophasor technology and wide area measurement system for transmission line protection, the differential protection scheme is a most suited scheme over the over-current, distance and directional protection. To investigate the impact of UPFC on alpha plane line current differential protection, detailed model of UPFC has been simulated in MATLAB and dynamic behaviour of the UPFC is considered. Moreover, an impact of different operation modes of UPFC and different compensation level on alpha plane characteristics are evaluated.