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This paper presents an application of singular perturbation theory to modeling induction motors in system simuladons. The focus is on model approximations and their impact on a motor's response to changes in system frequency as wall as voltage. The fast states associated with the motor stator and rotor dynamics are eliminated from a full motor model using singular perturbations with a first order correction factor added. This leads to a reduced order motor model referred to as the singularly perturbed model. The starting performance of this model is compared to that of a full model, and to that of a simple model in which the fast states are modeled by neglecting the rates of change of the fast variables. The response of the singularly perturbed model is much closer to that of the full model than is that of the model which neglects the rates of change of the fast variables completely. It is also noted that a corrected first-order slip model of the induction motor can yield a more accurate speed response than a conventional uncorrected first-order slip model during frequency and voltage changes. The response of models are also compared to disturbances applied to a two-area, four-machine power system and again the singularly perturbed model performance is closer to that of the full model than is the model with the rates of change of the fast states neglected completely. While the simulation time using the singularly perturbed model is longer than that using the simple model, it is considerably less than that of the full model. Index Terms--Singular perturbations, two-time scale, dynamics, long-term stability simulations, induction motors, transient stability.

Uses the results from a study into the application of the FACTS device, Static Compensator (STATCOM), to examine the application of the device for damping torsional oscillations in series ac systems. Information on the modeling of the STATCOM system; Functions of the STATCOM system; Digital simulation of the system.

Extensive research work has been conducted by the writers on the effects of barite, thinners, and fiocculants (in various concentrations) on freshwater bentonite muds. The PV-----versus-VP----curves were used to evaluate these effects. Definite, characteristic regularities were observed. Experiments have also been performed on salt-saturated atta-pulgite (Zeogel) muds on addition of various concentrations of pregelatinized starch and carboxymethylcellulose. The results were evaluated in terms of slope and location of PV----versus-yp lines. The yp/PKratio (i.e., slope of the PK----versus-yp line) is a significant indicator of drilling fluid condition. The P K---versus-yP curves can be used for evaluating the stability of drilling fluids. They can also serve as guidelines in the field control of the drilling fluid systems and in taking timely actions. [ABSTRACT FROM PUBLISHER]