Indian Journal of Science and Technology
Year: 2012, Volume: 5, Issue: 7, Pages: 1-5
Bahram Noshad1*, Mohammad Sadegh Javadi2 and Ali Esmaeelnejad3
1* Department of Electrical Engineering, Mahshahr Branch,
2 Department of Electrical Engineering, Science and Research Branch,
3 Department of Electrical Engineering, Science and Research Branch, [email protected], [email protected]
, [email protected]
*Author For Correspondence
Department of Electrical Engineering
Conventional second harmonic current restriction approach is an adopted method which has been implemented to transformer differential protection schemes. Because of unreliable nature of this approach in discrimination between inrush current, internal faults and external faults and due to the saturation of current transformers, we present new features of the differential protection scheme. This helps to determine the feasibility and applicability of the proposed approach in differential protective scheme for power transformer. The Current Transformer Saturation (CTS) phenomenon issue and its revelation is one of the most significant problems in power system protection particularly in the differential protection. In this paper, the saturation phenomenon and its effects on the differential protection are analyzed. Prevalent algorithms in digital signal processing which are implemented in power system cannot correctly recognize this phenomenon. Mal-operation of differential protection relay takes place when saturation in CT is appeared. This paper presents a Third-Difference Algorithm (TDA) for CTS recognition. In order to make comparison between the presented approach and prevalent digital protective algorithm, an identical case study is simulated. Simulation results also show that the TDA is both satisfactory and consistent with expectation. Keywords: Current transformer, Saturation phenomenon, Third-difference Algorithm, Internal and external faults.
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