Effect of unbalanced voltage on windings temperature, operational life and load carrying capacity of induction machine

Disturbances Rejection and Harmonics Reduction of Doubly Fed Induction Generator Based Wind Energy Conversion Systems

“…Since DFIG-based wind turbines are commonly Downloaded by [University of Saskatchewan Library] at 01:37 24 September 2012 connected to a weak grid, such as off-shore wind farms, great distortion in the voltage occurs every so often. When an unbalanced situation is imposed on the stator windings of a DFIG, not only does it result in the flow of currents with the respective harmonic order when electrically possible [7], but it also causes unbalanced magnetic loading of the machine that can lead to unexpected magnetic saturation [6] and excessive heating, which increases losses and reduces the effective lifetime of the DFIG [8]. System voltage harmonics also have undesired effects.…”

“…Figure 2 shows the overall block diagram of rotor converter control, which is directly established from Eqs. (7) and (8). By synthesizing these voltages over the rotor terminal of a DFIG, decoupled control of the DFIG will be achieved.…”

“…Since wind energy farms are usually constructed in rural or offshore areas, with weak local network or long transmission lines, voltage quality problems have turned to a frequent source of trouble. These problems can deteriorate the performance of a DFIG by introducing unwanted torque harmonics [6], inaccuracy in generation of commanded active and/or reactive power [7], saturation of the DFIG, and many other problems [4,[8][9][10]. Therefore, the effects of system distortions on the operation of DFIG are of great concern.…”

Prediction of internal temperature in stator winding of three-phase induction motors with ann

“…Running overload conditions occur when the motor is overloaded and operates at one or two times the rated current. Under this condition, the temperature increases or decreases gradually with a time constant that are large compared to the motor mechanical or electrical dynamics [2,[22][23][24].…”

Precise Assessment of Performance of Induction Motor under Supply Imbalance Through Impedance Unbalance Factor

“…This method reduces the complexity arises in transforming phase to sequence component and vice versa and also investigates the increases in losses under unbalance supply voltage condition. In all of these aforementioned studies [5][6][7][8][9][10][11], either the percent voltage unbalance (PVU) defined by NEMA [12], or VUF defined by IEC [13] [15], special emphasis is placed on the effect of the angle of CVUF on the performance of IM and most favourable and worst case for derating factor and maximum allowable slips are discussed whereas in [16] normalized negative sequence component is used in substitution to VUF to judge the effect of unbalance. Different definitions of the voltage unbalance are analyzed in [17] and by using these definitions the variation of the unbalance voltage in 3-D locus are plotted to reduce the range of the variation of terminal voltages.…”