Digital protection method for power transformers based on an equivalent circuit composed of inverse inductance

Journal Article · Sat Oct 01 00:00:00 EDT 1988 · IEEE Trans. Power Del.; (United States)

DOI:https://doi.org/10.1109/61.193949· OSTI ID:6568184

Inagaki, K; Higaki, M; Matsui, Y; Kurita, K ^[1]; Suzuki, M; Yoshida, K; Maeda, T ^[2]

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1. The Tokyo Electric Power Co., Inc., Tokyo (JP)
2. The Tokyo Electric Power Co. Inc., Tokyo (JP)

A new algorithm for the main protection of power transformers is described. Transformers can be represented by a universal equivalent circuit composed of inverse inductance, without reference to an internal fault. Results from analysis of inductance and inverse inductance matrices of actual transformers demonstrate that the values of the equivalent circuit elements at internal faults are remarkably different from those at a magnetizing inrush. The equivalent circuit elements have individual intrinsic values which can clarify the transformer internal operating conditions. By sampling voltage and current at each transformer terminal, the element values can be calculated by the new algorithm. The calculated value of the shunt inverse inductance enables a discrimination to be made between internal faults and magnetizing inrush without reference to current wave form. The proposed algorithm can recognize internal faults very quickly because of its high speed operation and judgment ability. Digital simulation results for large power transformers and experimental studies on a three phase bank of an actual single phase 21kVA transformer verify that the proposed algorithm can recognize internal faults within a half cycle of their occurrence.

• OSTI ID: 6568184
• Journal Information: IEEE Trans. Power Del.; (United States), Vol. 3:4
• Country of Publication: United States
• Language: English

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200104* - Fossil-Fueled Power Plants- Components