Shuffled Frog-Leaping Algorithm for Control of Selective and Total Harmonic Distortion

Abstract

The main purpose of active-filter based power-quality improvement problems is to reduce the total harmonic distortion(THD) and improve power factor (PF) as much as possible. However according to standards such as IEEE-519/IEC61000, selective harmonic distortion (SHD) should be controlled. The conventional power factor correction techniques,assume the voltage source to be purely sinusoidal. But it is rarely true because nonlinear loads draw nonsinusoidalcurrent from the source and that causes a nonsinusoidal voltage supply applied to the load. Under such conditions,any attempt to make the power factor unity by usual methods will result into a nonsinusoidal current, which increasestotal harmonic distortion (THD). On the other hand, harmonic free current does not necessarily result in unity powerfactor because of harmonics present in the voltage. Therefore, there is a trade-off between improvement in powerfactor and reduction of THD. One of the best solutions for this trade-off is to optimize PF while keeping THD and SHDinto their prespecified limits. In this paper five methods including shuffled frog-leaping algorithm (SFL), conventionalPSO (C-PSO), linearly decreasing inertia PSO (LDI-PSO), type 1 PSO (T1-PSO) and constant inertia PSO (CI-PSO)are employed in order to optimize PF while restricting the THD and SHD within the inertia constant. In this work, thecompensating current to be supplied by the shunt active power filter to the power system with these five optimizationmethods is applied and is observed using these evolution methods, PF has been improved considering all conditions.Also simulation results of a case study illustrate the high quality performance of SFLA among the algorithms used.