Particle Swarm Optimization and Genetic Algorithm based Power Quality Improvement

The term ‘power quality’ [1-2] refers to the purity of the voltage and current wave-form, and a power quality disturbance is a deviation from the pure sinusoidal form. Harmonics superimposed on the fundamental are one cause of such deviations. Power quality problems [1-2] like voltage harmonics, voltage flickers, voltage sags and voltage swells, current harmonics, current unbalance, reactive current etc. are studied.Conventionally passive L-C filters [3] were used to reduce harmonics and capacitors were employed to improve the power factor of the AC loads. However, the demerits of passive filters are fixed compensation, large size and resonance. The increased severity of harmonic pollution in the power networks has attracted the attention of power electronics to develop the dynamic and adjustable solutions to the power quality problems, generally known as active filters [3]. Classification of active power filters [3-4] based on converter type, topology, and the number of phases are presented.Active power filters use power electronic switches such as Thyristors, MOSFET’S, IGBT’S etc. They use 3phase inverters for generating compensating signals which are controlled by gate pulses generated by pulse width modulated controller[5].Unified Power Quality Conditioner [6, 9] which is a combination of series active power filter and shunt active power filter ,is used to mitigate voltage and current harmonics. The compensating principle of UPQC and its steady state analysis [1] is studied. The control techniques PI,PSO and GA are studied and applied in this work and compared with performance of FUZZY and ANN controllers [1, 7, 8and 9]... The theory about optimization techniques is studied and their applications to UPQC [11,12] is also studied.