Direct Interfacing of Dynamic Average Models of Line-Commutated Rectifier Circuits in Nodal Analysis EMTP-Type Solution

Abstract

Dynamic average-value models (AVMs) for AC-DC rectifier circuits are generally formulated in state-space form and hence are straightforward to implement in state-variable-based simulation languages. In the nodal analysis-based approach used in electromagnetic transient (EMTP-type) simulation packages, the development of AVMs requires additional effort to reformulate and interface the models with the external ac and dc networks. This paper proposes a new averaged-circuit model for three-phase line-commutated rectifiers which is directly interfaced with the ac and dc networks, thereby achieving a simultaneous solution of the respective variables in EMTP-type solution. The proposed model is verified against conventionally interfaced model, as well as detailed switching model of the original rectifier circuit. A significant improvement of numerical accuracy and stability of the solution is demonstrated even at fairly large time steps.