Survey of zero-residual-current arc suppression coil

There are two ways to realize the zero residual current in China. One is to add a capacitor in the lagging phase or a inductor in the leading phase of the grounding phase. It needs a split-phase-operating switch and a capacitor or inductor and results in a two-phase grounding fault artificially. The other is to inject current. It selects the faulty line and realizes zero residual current based on concept of APF. As the faulty line selection in resonance grounding system is still imperfect, if the faulty line is improperly selected, the successive grounding current estimation and inverter control will be totally wrong. As the compensation current of arc suppression coil can not be directly measured, the scheme of APF can not be simply applied to realize zero residual current.