A robust wide-area traveling wave-based fault location scheme for UPFC-compensated transmission networks

• Propose a wide-area travelling wave-based fault‑location scheme for grids with UPFC. • Aggregates all time of arrival data into a unified least squares formulation. • Robust against impacts of UPFC on traveling waves, noise, and measurement errors. • Sensitivity analyses show errors below 0.27% under diverse fault conditions. • The scheme is practically feasible in real-world wide-area protection systems. This paper proposes a novel wide-area fault location scheme based on the linear least squares method and graph theory for transmission lines. As the proposed method utilizes the initial arriving waves at substations, it is compatible with Flexible Alternating Current Transmission Systems (FACTS) devices. In the first step, the faulty zone is identified based on the time of arrival of the initial wave at each substation. The linear least squares method is then used to determine the faulted line and the fault location. The proposed method enhances prior approaches by (1) introducing a faulted line identification mechanism within the faulted zone, (2) estimating the fault location using a least squares approach, and (3) mitigating the impact of UPFC-induced wave distortions. The effectiveness of the method is validated in a sample 500 kV network using simulations for three different cases: (1) without a unified power flow controller (UPFC), (2) with a UPFC placed at a substation, and (3) with a UPFC at midline. The effects of various parameters, including fault resistance, fault type, fault occurrence time, sampling frequency, measurement errors, measurement noise, and loss of measurement data, are investigated. The results demonstrate that the proposed method accurately identifies the faulted line and precisely determines the fault location.