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Programmed pulse width modulation (PPWM) techniques require the solution of a set of nonlinear transcendental equations in order to obtain the switching angles. The main problem of almost all of them is solving these complex equations. Normally iterative methods such as Conjugate Gradient Descent Method and Newton-Raphson Method are used to solve these equations. To obtain convergence with numerical techniques, the initial values of the variables must be selected considerably close to the exact solution. Also In most cases only a local minimum can be obtained after considerable computational time. In this paper, a variant of differential evolution algorithm (DEA) is used to find the switching angles of a PPWM controlled inverter in a way that selected harmonics are removed from its output and the magnitude of fundamental is set at any desired level. The output waveform and spectrum results from simulation and experimental Digital Signal Controller (dsPic) PPWM inverter are presented to confirm the effectiveness of the proposed Weighted Differential Evolution (W-DE) method. [ABSTRACT FROM AUTHOR]

This paper investigates the capabilities of a proposed control strategy designed to enhance phase current profile in switched reluctance machine (SRM) drives. The new developed control concept can significantly accomplish the performance of the SRM in terms of efficiency, torque ripple and power quality when compared to standard PWM current control. This control consists of feeding each phase with a constant volt per hertz (V/f) law for low speed range. The suggested V/f method is simple and is easy for practical implementation. Principle of this mode of control and analytical expressions for current calculation are provided and discussed. Obtained simulation results demonstrate the effectiveness of the proposed control strategy. [ABSTRACT FROM AUTHOR]

Improving power systems transfer capability, voltage level control, damping electromechanical power oscillations and reducing transient swings becomes a great concern for national and/or private energy companies. Around the word, in particular in emerging countries, energy demand is in very fast growth. Developments of conventional and renewable energy production sources follow closely such fast increase in energy absorption. But, in general, developments in transmission lines and in hard and software control equipments are well delayed which implies a dangerous gap between the demand and the transmission capacity. Failures can give rise to power oscillation, voltage drop and high frequency deviations; resulting in system integrity rapid collapse by transient stability mechanism. New technology alternatives as FACTS can positively support conventional control systems as PSSs, AVRs and TGs .The paper deals with this problem and aims to show that UPFC is a suitable device in particular to reinforce variable wind energy penetration in the power system. [ABSTRACT FROM AUTHOR]