Transformer models for electromagnetic transient studies with particular reference to HVdc transmission.

Abstract

In this thesis a formulation for incorporating general magnetic equivalent circuits in electromagnetic transient programs is presented. The formulation is applied to create new single-phase, and the first three-limb three-phase PSCAD-EMTDC program transformer models. The new models proposed are validated with laboratory, factory, and field data. Problems associated with magnetically independent phase representations of three-limb three-phase transformers are discussed. Considerable differences are shown in the behaviour of three-phase bank and three-limb three-phase transformers, particularly for the case of in-rush studies. The new transformer models arc applied to: the first intervalidation of the Harmonic Domain Analysis program with the widely accepted PSCAD-EMTDC program, investigating the division of magnetising current harmonics between transformer windings, and the development of a new means to reduce HVdc converter dc side harmonics; the smoothing transformer. The first set of field measurements from a group connected generator HVdc converter station are presented. A PSCAD-EMTDC model for the group connection is validated with the field data and used to investigate the transient behaviour of three-phase bank and three-limb three-phase converter transformers. Considerable differences are shown in the case of a single-phase ground fault.