Multiphase Load-Flow Solution and Initialization of Induction Machines

Abstract

This paper presents a new method to model induction machines (IMs) in multiphase load-flow calculations. Fast convergence of the load-flow solution is achieved using an iterative Newton method in the modified-augmented-nodal-analysis formulation. The multiphase modeling approach allows accounting for unbalanced networks. The IM is modeled using either a constraint of electrical power input, mechanical power, or mechanical torque output. The slip of the IM becomes a load-flow variable computed iteratively while the reactive power is not fixed. In addition, the initialization of time-domain simulations using load-flow solution in the computation of electromagnetic transients is demonstrated using balanced and unbalanced network cases. It is shown that a seamless transition between load-flow and time-domain average powers is obtained when the slip of the IM is formulated as a variable in load-flow and its reactive power is not fixed.