Modeling and simulation, and their validation of three-phase transformers with three legs under DC bias
- Univ. of Colorado, Boulder, CO (United States)
This paper proposes a new model for three-phase transformers with three legs with and without tank under DC bias based on electric and magnetic circuit theory. For the calculation of the nonsinusoidal no-load currents, a combination of time and frequency domains is used. The analysis shows that (1) asymmetric three-phase transformers with three legs generate magnetizing currents with triplen harmonics not being of the zero-sequence type. (2) The wave shapes of the three magnetizing currents of (asymmetric) transformers are dependent on the phase sequence. (3) The magnetic history of transformer magnetization -- due to residual magnetization and hysteresis of the tank -- cannot be ignored if a DC bias is present and the magnetic influence of the tank is relatively strong, e.g., for oil-cooled transformers. (4) Symmetric three-phase transformers with three legs generate no-load currents without triplen harmonics. (5) The effects of DC bias currents (e.g., reactive power demand, harmonic distortion) can be suppressed employing symmetric three-phase transformers with three legs including tank. Measurements corroborate computational results; thus this nonlinear model is valid and accurate.
- Sponsoring Organization:
- USDOE, Washington, DC (United States)
- OSTI ID:
- 352481
- Journal Information:
- IEEE Transactions on Power Delivery, Vol. 14, Issue 2; Other Information: PBD: Apr 1999
- Country of Publication:
- United States
- Language:
- English
Similar Records
Experimental analysis of a DC bucking motor blocking geomagnetically induced currents
Reactive power and harmonic compensation based on the generalized instantaneous reactive power theory for three-phase power systems