Modeling and Simulation of Air Conditioner Motors and Investigation of Cascaded Stalling

Abstract

Air conditioner (A/C) motor stalling is considered as one of the main reasons for the occurrence of delayed voltage recovery events leading to voltage collapse. In recent years, the phenomenon of Fault-Induced Delayed Voltage Recovery (FIDVR) has increasingly been observed. Planning tools have been found inadequate to capture FIDVR-type events, primarily due to inaccurate modeling of A/C motor loads. A dynamic A/C motor model based on the phasor modeling approach is considered in this work. The model accurately represents the behavior of A/C motors during and after a fault. Sensitivity analysis is performed to arrive at a set of more significant model parameters. This information may be used effectively in tuning the model parameters for various types of A/C motors. The next step in the development of a load model capable of accurately capturing the dynamical behavior of loads in the system is the aggregate modeling of several A/C motors. Instead of using a simplistic method of aggregating these machines into a single equivalent machine based on their ratings, an analytical approach based on bifurcation theory is presented in this work. The method characterizes the stalling behavior of several A/C motors in the system based on the system voltage level and thus provides a way for a more refined approach to aggregate A/C motor modeling.