A nonlinear lumped parameter model for transient studies of single-phase core form transformers
Power transformers, in service, are subjected to voltage transients. The transformer insulation should be designed to withstand the internal stresses initiated by these transients. To determine these stresses during the design stage, lumped parameter models of the transformer are employed. Computer models are the best tools for predetermination of these stresses. To date, in spite of the great efforts employed, lack of accurate and consistent transformer models are felt to contribute to the relatively high failure rate of the EHV transformers. This thesis is based on a detailed transformer model developed by G.E. for transformer insulation design. Although this model has provided the designer a suitable tool for transient study during design stage, it assumed a linear characteristic for iron core and employed an empirical method to model damping effect of transformer losses. It is felt that the core`s non-linear magnetic characteristic has an appreciable effect on the transformers transient response. This thesis develops a detailed transformer model which accurately models the nonlinear, saturable, characteristic of transformer magnetic core. The model is based on linearization of the core`s saturable characteristic during each time interval of solution. Then the linear model is solved within that interval and based on the magnetizing flux in the core, the inductance model is adjusted for the next time interval of solution, and the updated linear model is solved for the interval. A stable solution routine is developed to solve the nonlinear model`s system of O.D.E.`s. Supplementary features needed for transformer design such as external circuits, switches and nonlinear resistors are developed for this solution routine. The necessary methods are developed for verification of the linear transformer model in the frequency domain.
- Research Organization:
- Rensselaer Polytechnic Inst., Troy, NY (United States)
- OSTI ID:
- 50672
- Resource Relation:
- Other Information: TH: Thesis (Ph.D.); PBD: 1993
- Country of Publication:
- United States
- Language:
- English
Similar Records
Computing the internal transient voltage response of a transformer with a nonlinear core using Gear`s method. Part 1: Theory
Computing the internal transient voltage response of a transformer with a nonlinear core using gear`s method. Part 2: Verification