Indian Journal of Science and Technology

Open Access Open Access  Restricted Access Subscription Access

Discrimination between Internal Faults and Inrush Current Phenomena in Power Transformers


Affiliations
1 Department of Electrical Engineering, Mahshahr Branch, Islamic Azad University, Mahshahr, Iran, Islamic Republic of
2 Department of Electrical Engineering, Science and Research Branch, Islamic Azad University, Fars, Iran, Islamic Republic of
 

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
User

  • BunyagulT, Crossley P and Gale P (2001) Overcurrent protection using signals derived from saturated measurement CTs.IEEE PES 2001 SM, Vancouver, BC, Canada.

  • Document ABB (2007) Applying high impedance differential protection with IED 670. Application Example. 1-12, ABB.

  • Fernández C (2001) An impedance-based CT saturation detection algorithm for bus-bar differential protection. IEEE Trans. Power Delivery. 16(4), 1203- 1209.

  • Kang YC, Kang SH and Crossley P (2003) An algorithm for detecting CT saturation using the secondary current third-difference function. IEEE Bologna Power Tech Conf., Italy.

  • Kang YC, Wo. L, Jhong. E. (2004) Design and evaluation of an algorithm for detecting current transformer saturation. IEE Proc. Gener. Transm. Distrib., 151 (1), 27-35.

  • Kang YC, Wo. L, Jhong. E. (1997) An algorithm for compensating the secondary current of current transformers.IEEE Trans. Power Delivery. 12 (1), 116- 24.

  • Kitayama M and Nakabayashi M (2002) A new approaach to fast inrush currenrt discrimination based on transformer magnetizing charachtristic.14th PSCC (Sevilla). pp: 1-7.

  • Phadke AG and Thorp JS (1988) Computer relaying for power systems. Research Studies Press LTD.


Abstract Views: 549

PDF Views: 189




  • Discrimination between Internal Faults and Inrush Current Phenomena in Power Transformers

Abstract Views: 549  |  PDF Views: 189

Authors

Bahram Noshad
Department of Electrical Engineering, Mahshahr Branch, Islamic Azad University, Mahshahr, Iran, Islamic Republic of
Mohammad Sadegh Javadi
Department of Electrical Engineering, Science and Research Branch, Islamic Azad University, Fars, Iran, Islamic Republic of
Ali Esmaeelnejad
Department of Electrical Engineering, Science and Research Branch, Islamic Azad University, Fars, Iran, Islamic Republic of

Abstract


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

References





DOI: https://doi.org/10.17485/ijst%2F2012%2Fv5i7%2F30508