Accuracy enhancement of the JMarti model by using real poles through vector fitting

The JMarti model is used worldwide for electromagnetic transient simulations of transmission lines. This paper proposes increasing the accuracy of the model by using only real poles through vector fitting. The JMarti model uses a rational approximation process that ends in models that include only real poles and zeros. By using vector fitting to synthesize the functions of the JMarti model, one can have complex and real poles. In this work, a process in which complex poles are replaced by real ones, based on the non-dominance of complex poles for smooth functions, is implemented. The improvement in the accuracy is demonstrated through the ATP-EMTP (alternative transient program) program by modeling two cases: a single-phase transmission line configuration and an asymmetrical overhead line configuration. Additionally, the solutions of the test cases with the numerical Laplace transform are taken as references. The results show that, through the proposed methodology, not only an increase in accuracy possible but also the proposed methodology also can be used to improve the computational efficiency of the JMarti model. The presented methodology can easily be applied to any application in which the frequency response data present a smooth behavior. Finally, the presented methodology can be easily applied in an iterative way.