Principle and Control Design of Active Ground-Fault Arc Suppression Device for Full Compensation of Ground Current

Abstract

Traditional ground-fault arc suppression devices mainly deal with capacitive component of ground current and have weak effect on the active and harmonic ones, which limits the arc suppression performance. The capacitive-current detection needed in them suffers from low accuracy and robustness. The commonly used large-capacity reactive component may bring about overvoltage because of possible resonance with the distributed phase-to-ground capacitance. To solve these problems, an active ground-fault arc suppression device is presented. It employs a topology based on a single-phase inverter to inject current into the neutral without any large-capacity reactors, and, thus, avoids the aforementioned overvoltage. It compensates all the active, reactive, and harmonic components of the ground current to reliably extinguish the ground-fault arcs. A dual-loop voltage control method is proposed to realize arc suppression without capacitive-current detection. Its time-based feature also brings the benefit of fast response on ground-fault arc suppression. The principle of full current compensation is analyzed, together with the controller design method of the proposed device. Experiment on a prototype was carried out to validate the effectiveness of the device.