SIMPLIFIED APPROACH TO THE DETERMINATION OF INDUCTION MACHINE DYNAMIC RESPONSE.

Utilizing non-dimensional parameters based on the rotor transient time constant, a set of curves and a number of useful approximate expressions are presented for determining the small signal dynamic response of induction machines. These results permit rapid estimation of damping and oscillation frequency for a wide range of operating conditions including variations in line frequency. Stability and minimum damped operation are studied in detail and curves are presented to allow accurate determination of the operating condition, the degree of damping, and the oscillation frequency at the minimum damped operating point. The two most significant parameters influencing the dynamic response are shown to be the normalized operating frequency and a non-dimensional gain factor dependent on the slope of the steady state speed-torque curve, the rotor transient time constant, and the inertia. A table of parameter values for a representative group of induction machines from sub-fractional to 8000 hp is included to illustrate the trends to be expected as a function of machine size.