Robust Padé approximation for the holomorphic embedding load flow

This paper proposes an application of the robust Padé approximation algorithm to make solutions of load flow problems reliable. Difference between the classical Padé approximation algorithm and the robust version based on the Singular Value Decomposition (SVD) is described. The robust approximation method is able to determine an optimal rational function approximation using the coefficients of a Taylor series expansion. As a consequence the voltage collapse point as well as the steady-state voltage stability margin can be calculated with high reliability. Voltage collapse points (i.e. branching points) are identified by using locations of poles/zeros of a rational function approximation. Numerical examples are devised to illustrate potential use of the proposed method in practical applications.