Re-examination of Synchronous Machine Modeling Techniques for Electromagnetic Transient Simulations

This paper re-examines the three synchronous machine modeling techniques used for electromagnetic transient simulations, namely, the qd model, phase-domain model, and voltage-behind-reactance model. Contrary to the claims made in several recent publications, these models are all equivalent in the continuous-time domain, as their corresponding differential equations can be algebraically derived from each other. Computer studies of a single-machine infinite-bus system demonstrate that all of these models can be used for unsymmetrical operation of power systems. The conversion of machine parameters is also discussed and is shown to have some impact on simulation accuracy, which is acceptable for most cases. When the models are discretized and interfaced with an EMTP-type network solution, the voltage-behind-reactance model is shown to be the most accurate due to its advanced structure.