Wide-area Fault Location of Transmission Lines by Hybrid Synchronized/Unsynchronized Voltage Measurements

Global positioning system (GPS) has been deployed in phasor measurement units and protective relays to provide synchronized measurements across the grid. Synchronized measurements, however, may not be available throughout the network either due to GPS signal loss (GSL) or basically lack of required infrastructure for synchronized sampling. This paper presents a novel method for wide-area fault location incorporating both synchronized and unsynchronized voltage measurements. Complex calculus is utilized to develop a system of equations based on phase angles of synchronized measurements and magnitudes of both synchronized and unsynchronized measurements. The distributed-parameter model of the transmission lines are considered and therefore the obtained results are also valid for long transmission lines. Moreover, the proposed formulation locates the fault irrespective of fault type. Electromagnetic transient simulations for WSCC 9-bus and a 22-bus sub-network of the IEEE 118-bus test system reveal that in the face of GSL, unsynchronized measurements significantly improve fault-location estimation when the synchronized measurements are sparse.