Compensation of Variative Tap in Differential Protection of Electric Arc Furnace Transformer

This paper deals with a new method to compensate variative tap negative impact on transformer differential protection of electric arc furnace (EAF). An EAF's transformer has some challenges to be protected by a differential protection. Among them, high rating secondary current, similarity of normal operation and fault condition, and many tap variations during melting procedure can be addressed. If variation of the tap is not included in differential protection, the relay will be faced to maloperation. In the proposed method, by comparison of the differential current with a predefined threshold and considering tap changer signal, a proper decision making is carried out for the compensation. The performance of the method is assessed using many simulation of a typical system in different conditions.