Multivariate Analysis of Transformer Resonant Overvoltages in Power Stations

In this paper, cable-transformer resonant overvoltages are studied on the low-voltage (LV) side of a 410-MVA generator step-up (main) transformer, due to ground fault and energization. The transformer is placed in a network configuration often found in Norwegian hydropower stations. The overvoltages...

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Bibliographic Details
Published in:IEEE transactions on power delivery 2011-10, Vol.26 (4), p.2563-2572
Main Authors: Gustavsen, Bjørn, Brede, A. P., Tande, J. O.
Format: Article
Language:English
Subjects:
Applied sciences
Cable
Current limiters
Electric connection. Cables. Wiring
Electric power plants
Electrical engineering. Electrical power engineering
Electrical power engineering
Exact sciences and technology
Hydroelectric power generation
Hydroelectric power plants
Laplace transforms
Miscellaneous
Multivariate analysis
overvoltage
Power cables
Power generation
power station
Power transformer insulation
Resonance
transformer
Transformers and inductors
Transient analysis
Various equipment and components
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Summary:In this paper, cable-transformer resonant overvoltages are studied on the low-voltage (LV) side of a 410-MVA generator step-up (main) transformer, due to ground fault and energization. The transformer is placed in a network configuration often found in Norwegian hydropower stations. The overvoltages are calculated when systematically varying the length of the high-voltage (HV) side cable and that of the cable between the main transformer LV side and the station transformer. This multivariate analysis is performed efficiently, using frequency-domain calculations and the inverse Numerical Laplace Transform. Time-domain simulations are used for analyzing the critical cases in detail. Both types of calculations make use of a blackbox, wideband model of the transformer, and novel procedures are introduced for initializing computations from correct 50-Hz initial conditions. Among the findings are that extreme overvoltages can occur on the station transformer if current-limiting reactors are placed in series with the cable between the main transformer LV side and the station transformer.
ISSN:0885-8977
1937-4208
DOI:10.1109/TPWRD.2011.2143436