Fault Location on Series-Compensated Transmission Lines Using Incremental Quantities and Emulating a Nonlinear Metal-Oxide Varistor

This paper presents a staged two-terminal fault-location method for transmission lines with series compensation, based on incremental quantities and a least-squares error (LSE) formulation. The fault distance is first established through an analytical estimator with a bounded linear capacitive correction. This distance is subsequently held fixed during subsample time alignment and the emulation of the nonlinear capacitor and metal-oxide varistor (MOV), thereby preventing the later correction stages from shifting the fault location solely to reduce the fitting residual. Among the 18 paired Common Format for Transient Data Exchange (COMTRADE) records, 10 cases corresponded to the reference distance category, including seven instances with series compensation and three instances without compensation. For these 10 records, the proposed procedure achieved a mean absolute error of 2.26 km, with eight cases within 5 km; excluding the record used during method development, it was 2.48 km, with seven of nine within 5 km. For the compensated subset, the mean absolute error decreased from 4.44 km (raw LSE) to 3.04 km (from 3.94 to 3.50 km excluding that record), whereas the uncompensated subset yielded 0.43 km. Sensitivity and stress analyses quantify the influence of the incremental delay and delimit the applicability of the time-alignment and residual-diagnosis stages. The results show the performance of the staged formulation on the available records while indicating the need for broader field and electromagnetic-transient validation before generalization to other compensation levels, MOV characteristics, and fault-resistance conditions.