Adaptive distance protection setting in presence of mid-point STATCOM using synchronized measurement

EHV and HV transmission lines are used widely to transfer power from power generating area to large load centers. Nowadays compensating devices which uses modern power electronic devices are mostly used to improve the power transfer capability of transmission lines. Use of FACTS devices in transmission lines affect protection system very drastically. In this paper, the issues related with distance protection of transmission lines with STATCOM connected at mid-point are addressed. To mitigate the problems associated with distance protection, a novel algorithm based on synchronized measurement for adaptive relay setting is proposed. The power system is modeled in EMTDC/PSCAD software with frequency dependent model of transmission line. The results obtained for the new adaptive setting scheme are accurate, robust and superior in comparison with those obtained from existing distance protection schemes for transmission line with STATCOM.