Comparison between overcurrent relay and developed PMU based protection

Abstract

Power system protection is still one of the primary focus of the utility companies. Phasor Measurement Unit (PMU) is used to measure the data of the transmission line, buses and the equipment's associated with it. The data measured by the PMU's at different locations can be used to make the decisions for faulty and healthy zone in the power system. During fault condition at specific location in the power system, the data measured by PMU will show abrupt increase or decrease in the physical quantities like voltage, current, and phase angles. Based on the PMU values the relays associated with the faulty transmission lines will be triggered which in turn helps to isolate only the faulty portion of the system from the rest of the healthy portion of the power system. This paper will compare two protection schemes: one protection scheme is based solely on the protective relays while the other protection scheme utilizes both the protective relays and the PMUs. Both the protection schemes were tested in real time (using RTDS) on the 3-bus power system for all kinds of line-to-ground faults.