Prediction of induction-motor dynamic performance in power systems

The application of the o-d-q transformation (due to Park) to the induction-machine equations is used to develop a set of equations suitable for use with a digital computer in the analysis of dynamic performance. The method of calculation is designed to be compatible with those already in use for the analysis of synchronous-machine behaviour and makes use of a novel equivalent circuit. An account is given of measurements taken on a range of laboratory motors to determine the variation of the principal parameters of the equivalent circuit with slip and voltage. A method of analysis is discussed which allows an adequate representation of an induction motor to be included in stability studies. The measured performance shows good agreement with that predicted using the computer program for the case where a small motor is fed from a larger machine which has lost synchronism, and an indication of the effect of neglecting some of the corrections is included.