Efficient and Precise Dynamic Initialization of Induction Motors Using Unified Newton–Raphson Power-Flow Approach

Abstract

An accurate initialization is very important for power-system dynamic simulations. Using conventional power-flow model to initialize induction motors is not straightforward because an unavoidable mismatch between pre-specified reactive powers from power-flow calculation and the ones, actually required by motors. To overcome this problem, this paper presents a unified method for incorporating a nonlinear model of induction motors into Newton–Raphson (NR) power-flow algorithm, allowing precise steady-state solutions of power networks with induction motors to be solved simultaneously. The power-flow results of the extended algorithm are then compared with benchmark results for model verification. The ability of the extended algorithm is also demonstrated using IEEE-30 bus and 118 bus test systems with large groups of induction motor loads. The studied results indicate that the presented algorithm not only gives exact steady-state initialization without existence of the reactive power mismatches but also preserves powerful Newton–Raphson's quadratic convergence characteristics.