Dynamic Modeling of Single-phase Induction Motor Loads

Single-phase induction machines are found in various appliances such as refrigerators, washing machines, driers, air conditioners, and fans. Large concentrations of single-phase induction motor loads such as air conditioners and other motorcompressor loads can adversely impact the dynamic performance of a power system. An understanding of the dynamics of this type of induction machine is needed to improve the current state of the art in running power system dynamic studies. In this thesis, a novel approach of modeling an exact fourth-order model of a single-phase induction machine is developed that gives credence to the well-known double revolving-field theory. Using a standard averaging technique, an augmented seventh-order dynamic model is derived using forwardand backward-rotating components. The double-frequency terms causing torque and speed pulsations in the original model can be recovered as a byproduct of the theory. It is proved that two three-phase induction machines with their stator windings connected in series but with opposite phase sequence have the same dynamical behavior as the averaged single-phase induction machine model. The dynamic and steady-state performances of the single-phase machine are investigated using the new augmented model and compared with the exact model.