Considerations of neutral current protection operation during cascade short-circuit of capacitor unit

This paper addresses the problem of the capacitor bank neutral current protection operation during cascade short-circuit of capacitor units. A specific example bank is used to assist in the understanding and use of this information that can be applied to all ungrounded neutral double-wye capacitor banks including modern all-film capacitors with external expulsion fuses. The performed analysis is based on the developed analytical expressions of state variables in unbalanced conditions of these capacitor banks. An approach to prevent a misoperation of the neutral current protection during the progressive failure of capacitor units is proposed.