A linearized MOV model-based method for fault location on off-terminal series capacitor bank-compensated transmission line using one-end current

Abstract

This paper proposes a method for fault location on single and double-circuits series capacitor bank-compensated transmission line (SCTL). A common situation for installing the series capacitor bank (SCB) is to place it some point away from the terminal substations. One-end measurement-based fault locators are favorable for many utilities due to simplicity and less cost especially if they are accurate enough. For impedance-based one-end fault locators on SCTL, the current passing in the SCB is unknown for about 50% of faults. This prevents the prediction of the challenging metal oxide varistor (MOV) behavior that is inevitable for a one-end method. Herein, the nonlinear characteristics of the MOV protecting the SCB are simplified by a linearized simple yet precise model. This makes it possible to express the SCB-MOV characteristics as a linearized function of the far-end current for faults upstream the SCB keeping the nonlinear characteristics of the MOV. This eventually enables to estimate the fault current contribution of the far-end. Hence, an analytical fault distance estimation algorithm is derived for both single and parallel transmission lines using the sequence-networks modeling of the system. Beside simplicity and robustness, the proposed method is found to be accurate enough in locating a big number of faults under a variety of conditions.