Protection of power transformer using multi criteria decision-making

• We proposed an overall protection scheme for power transformers.
• REF relay and directional check unit are combined with the differential relay.
• The proposed relay covers protection blind spots of the power transformer relays.
• Effectiveness and merit of the proposed relay are shown by extensive simulations.
• The relay is a multi criteria based scheme for power transformers protection.

Power transformers are protected by different relays that operate independently. Malfunction of each relay has a major role in reducing the reliability of the protection system. In order to mitigate the main drawbacks of the power transformer relays, an overall protection scheme is presented in this paper. This scheme proposes a novel multi criterion algorithm using decision-making based on fuzzy logic. In this paper the outputs of restricted earth fault relay and a directional check unit, are combined with the output of the differential protection relay. Therefore, problems that are pertaining to independent operation of each relay have been mitigated and the relays cover protection blind spots of each other. The improved power transformer protection (IPTP) scheme enhances the sensitivity and reliability of the power transformer protection. Extensive simulations are used to measure the effectiveness and merit of the proposed IPTP relay. The above efforts result in a multi criteria approach for protection of power transformers.