Direct Interfacing of Parametric Average-Value Models of AC–DC Converters for Nodal Analysis-Based Solution

AC–DC converters are widely used in many power-electronic-based systems. There is an increasing need to simulate such systems using larger time-steps in offline and/or real-time electromagnetic transient (EMT or EMTP) simulators. The so-called parametric average-value models (PAVMs) have been developed to allow larger time-steps and provide fast simulations. However, the application of PAVMs in nodal-analysis-based EMTP programs typically requires a one-time-step delay between the interfacing sources and the network solution (i.e., indirect interfacing), causing inaccuracy and numerical instability at medium-to-large time-steps. This paper presents a direct interfacing method for PAVMs of line-commutated rectifiers (LCRs). The proposed method linearizes the PAVM interfacing equations and incorporates the respective sub-matrices and history terms into the network nodal equations, which eliminates the need for a time-step delay. Simulation studies verify the effectiveness of the proposed method in EMTP-type solution wherein very good accuracy and numerical stability is achieved at fairly large time-steps, which has not been previously possible with conventional methods.