The basic theory of the single-phase transformer has been described, including the derivation of parameters, the modelling of magnetisation non-linearities and its numerical implementation in a form acceptable for electromagnetic transients programs. The need for advanced models has been justified, and a detailed description made of UMEC (the Unified Magnetic Equivalent Circuit), a general transformer model developed for the accurate representation of multiphase, multiwinding arrangements. UMEC is a standard transformer model in the latest version of PSCAD/EMTDC. Rotating machine modelling based on Park's transformation is reasonably stan dard, the different implementations relating to the way of interfacing the machine to the system. A state variable formulation of the equations is used but the solution, in line with EMTP philosophy, is carried out by numerical integrator substitution.

Inspec keywords: machine windings; EMTP; equivalent circuits; power transformers; power system CAD; magnetisation

Other keywords: magnetisation nonlinearity; multiwinding arrangements; PSCAD/EMTDC; Park transformation; EMTP philosophy; single-phase transformer; machine model; power transformers; rotating plant; unified magnetic equivalent circuit; UMEC; electromagnetic transients programs

Subjects: Transformers and reactors