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Large medium- and high-voltage (MV and HV) squirrel-cage induction motors are widely used in most industrial processes. Their starting times are very much required for suitable setting of over-current-protective devices and assessing power quality of distribution power system. Mostly, the starting time can be precisely computed from time-domain numerical computation. This approach is rather tedious...
Medium-and high-voltage induction motors are widely used in industrial applications. Estimations of their operating currents are very much required for assessment of their steady-state performances. This paper presents a new analytical approach to estimate motor's slip-current curve from their technical catalog data. An accuracy of the proposed technique is validated by comparing the slip-current...
unbalanced voltages seriously affect steady-state performances of induction motors. In this paper, analytical formulation for finding the steady-state operating points of induction motors with different load torque profiles is presented when the motors are operating under unbalanced condition. The effect of single-phase voltage unbalance on motor performance is demonstrated as the load torque of induction...
Induction motors are widely used every production process today. Their torque-speed characteristics are the most important properties. This paper describes a simple and efficient analytical technique to determine speed-torque performance curve of induction motor from manufacturer data. The obtained speed-torque curve is verified against that derived from the conventional equivalent model where the...
Self-excited induction generators (SEIG) are alternately considered for electricity production in remote villages and rural areas since they have great advantages in term of low cost, less maintenance, and very robust construction features. Most of the SEIG load in the areas is normally lighting and heating. However, the SEIGs are capable of feeding the dynamic loads such as induction motors. The...
Self-excited induction generators (SEIG) are increasingly employed in remote areas for electricity production from wind energy. Analyzing of a stand-alone SEIG dynamic performance is largely limited to static load. This paper presents dynamic simulation of small SEIG feeding induction motor (IM) load. Mathematical models of SEIG, IM, and wind turbine are at first clearly implemented into Matlab/Simulink...
Hyperbolic Takács model has been accepted and widely used for hysteresis loop representation of magnetic materials. In this paper, the original Takács model is extended to include Gaussian function for accuracy improvement of soft magnetic material. The modified hysteresis model is then incorporated into single-phase transformer model in the Matlab/Simulink environment. An accuracy of the modified...
Self-excited induction generators (SEIG) are mostly exploited in isolated areas to generate electrical energy. Analyzing of a stand-alone SEIG dynamic performance is largely limited application of the SEIG to static load. This paper presents dynamic simulation of small SEIG feeding induction motor (IM) load. Mathematical models of SEIG, IM, and wind turbine are clearly implemented into Matlab/Simulink...
A constant power load model is normally used in power flow analysis. The constant power load fails to describe nonlinear characteristic of all power system loads. Hence, this paper presents an extended technique to incorporate nonlinear profile of a composite load model into Newton-Raphson power flow calculation. The power flow solution with a group of induction motors and static loads is demonstrated...
Induction motor loads constitute almost half of the total load in interconnected power system. In power system stability analysis, it is commonly used a single equivalent model to represent whole groups of induction motor load regardless of their horse power rating. This technique may not give an accurate result due to their nonlinear differences. Hence, this paper demonstrates steady-state nonlinear...
In power system dynamic studies, it is necessary to represent induction motor loads with a standard reduced order model in order to reduce computational requirements. A third-order model, neglecting the stator transients, is often used. In this paper, the third-order model is further simplified into two second-order models, called as slip-flux-magnitude and slip-flux-angle models. The model derivations...
This paper proposes a simple method for aggregating a group of induction motors, which are connected at the same bus. The parameters of aggregate motor are derived using a technique based on energy conservation law. An accuracy of the aggregate model of multiple motors is verified by comparing dynamic responses obtained from the sum of individual motor and the aggregate motor. The obtained results...
Voltage sags is a problem affecting the electrical qualities. In this paper, effects of small and large induction motors on voltage sag profile are compared and discussed. The study results show that as the fault is initiated, reactive power contribution from the large HP motor is more significant to prevent fast collapse of the voltage, resulting in non-rectangular shape of sag. The motor's negative...
Voltage sags is a problem affecting the electrical qualities. In this paper, effects of large induction motors on voltage sag characteristic are discussed. Moreover, the influences of different mechanical loads of the motors on voltage recovery are investigated. The study results show that reactive power contribution owing to the motor's trapped flux linkage prevents fast collapse of the voltage,...
This paper proposes an extended method of Newton-Raphson power flow algorithm to incorporate nonlinear model of induction motor loads. The proposed method is used for finding correct power system operating conditions, which can be employed for solving the problem of initializing the dynamic models of induction motor in stability studies. The power flow solution with a group of induction motors is...
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