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Slip energy recovery induction motor drives are used in high power applications, in which by controlling the slip power a variable speed drive system is provided. However, poor power factor is a disadvantage of the system. Presence of sub-harmonics of the line frequency on the stator side is one of the special features of these drives. Phase-controlled inverter can absorb the reactive power from the supply and inject the low-order current harmonics with relatively high amplitudes to the supply. This paper simulates the harmonic content of waveforms in various points of drive at different speeds, based on the hybrid model (dqabc). Then the sinusoidal pulse-width-modulation (SPWM) control technique is used in order to improve the power factor of the drive and to weaken the injected low-order harmonics to the supply. Based on the frequency spectrum, total harmonic distortion, distortion factor and power factor, two phase control and SPWM techniques are compared and the advantage of the SPWM technique over the phase control technique is shown.Index Terms-Harmonic analysis, slip energy.

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SUMMARY In recent years, because of structure renewal, development, and progressive distribution, many of the economical and technical characteristics of power systems in the various parts of production, transmission, distribution, and consumption have been changing. Especially, the transmission systems have been affected to a great degree because of the increase in demand and limitation in the new lines formation. One of the shortcomings of this affair is the risk of losing stability after turbulence occurrence. The controllability and stability of power systems can be increased by FACTS devices. One of the FACTS devices is Interline Power‐Flow Controller (IPFC) by which the voltage stability, dynamic stability, and transient stability of power systems can be improved. In the present paper, the convenient operation and control of IPFC for transient stability improvement are considered. Considering that, the system's Lyapunov energy function is a relevant tool to study the stability affair. IPFC energy function optimization has been used in order to access the maximum of transient stability margin. In order to control IPFC, ANFIS which is a neuro‐fuzzy controller has been used. The designing results have been studied by the simulation of a single‐machine system with infinite bus and another standard 9‐buses system (Anderson and Fouad, 1977). Moreover, with simulating of other FACTS devices, such as unified power flow controller (UPFC), static synchronous series compensator (SSSC), and static synchronous compensator (STATCOM) and comparing the results, the superiority of IPFC is proved. Copyright © 2012 John Wiley & Sons, Ltd.

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