Resonance frequency‐based protection scheme for ultra‐high‐voltage direct‐current transmission lines

Abstract

Direct-current (DC) line faults are a major issue in ultra-high-voltage direct-current systems due to the complex and wicked environment. Thus, reliably detecting and isolating the DC line faults are not a trivial engineering task. This study proposes a DC line protection scheme based on resonance frequency. The scheme mainly consists of a fault discrimination criterion and a faulty pole selection criterion. The fault discrimination criterion is based on the phase of the resonance frequency impedance, and it is deployed to differentiate the faults on the protected DC line from the external faults. The faulty pole selection criterion is based on the ratio of the resonance frequency currents, and it is employed to select the faulty pole. The sensitivity analysis demonstrates that the performance of the proposed protection is promising. The simulations carried out in PSCAD/EMTDC under various conditions verify the feasibility and validity of the proposed protection scheme.