Real-time validation of ERF-based scheme for shunt-compensated/uncompensated line

This paper presents the real-time validation of an ERF-based fault detection scheme for shunt-compensated and uncompensated transmission line. The ERF is defined as the sine of the phase difference between the Static synchronous Compensator (STATCOM) tap voltage and differential current. The STATCOM tap voltage can be estimated using local end voltage and current. The ERF is measured at both the relay ends. In the capacitive mode, if both ERFs are more than the upper threshold, the fault is external and if any ERF is less than the upper threshold, the fault is internal. In the inductive mode, if ERF is between upper and lower threshold, the fault is internal else, if the differential current is more than the modified differential current setting, the fault is internal else the fault is external. The performance of presented scheme is first investigated for various faults at various locations with EMTDC/PSCAD simulations. Then scheme is successfully validated using Real-Time Digital Simulator (RTDS). It is found that the scheme is robust and selective for various faulty conditions.