Degree Type


Date of Award


Degree Name

Doctor of Philosophy


Electrical and Computer Engineering


The research contributes to the identification of dynamic equivalents of large numbers of induction motors for the purpose of load modeling. A model for a group of induction motors for starting as well as running studies is developed. The improvement areas are validity of the model over the whole speed range (zero to full load speed), effects of deep-bar rotor, accuracy, computational requirements and data requirements;The grouping is based on the representation of each individual machine by its equivalent circuit. The proposed model reduces a large number of equivalent circuits into one single equivalency. The new circuit contains variable parameters whose variation depends on the motors to be grouped. The reduced single model also has a reduced single inertia and combined load characteristics. The response of the reduced model and the summation of the responses of all the individual machines were nearly identical for both computer simulation and experimental results;Although the proposed model could be used for any number of machines, considerable simplification was achieved by grouping all induction machines into a small number of categories. These categories are a function of the rating and the run-up times of the individual machines;Voltage dip simulations on a small distribution system were performed and the results are presented. The results from the equivalent reduced model agree well with the results obtained from a detailed analysis of each machine. Also, the reduced load model was compared with a static load model for transient stability studies.



Digital Repository @ Iowa State University,

Copyright Owner

Farzan Roohparvar



Proquest ID


File Format


File Size

141 pages