Traveling Wave-Based Setting Free Fault Location for Transmission Lines Using Unsynchronized Data

A method is proposed for locating fault on two-terminal transmission lines using traveling-waves from two-ended unsynchronized current measurements. It considers the line length to be divided into four zones and computes per unit fault locations assuming the fault to be present in each of these zones separately. It then estimates the faulted zone, and the corresponding fault location estimate is displayed as the final output. These computations involve measuring three travelling wave arrivals at each terminal. The method is free of wave speed (or line parameter) input and is inherently immune to data synchronization issues. It is tested on a 200 km transmission line simulated in PSCAD/EMTDC. The performance is also compared with a classical two–terminal method. The method is further validated with a variety of test scenarios. It is applied to series compensated transmission line with the compensator placed at one end, both ends and at any intermediate location on the line. Testing is extended to lines connected to inverter-based renewables and long export cables connecting offshore wind to the main grid. The method works satisfactorily for varied fault cases in the above-mentioned scenarios. It is robust to errors in wave speed and data synchronization errors. To demonstrate performance with practical measurements, the method is tested using a field case of a 400 kV series compensated line in the Indian Power Grid.