Hybrid filter applications for power quality improvement of power distribution networks utilizing renewable energies

A hybrid filter constructed of a shunt active filter and distributed passive filters used for power quality improvement in dispersed generation system is presented. The distribution system consists of several kinds of renewable energies as DG units where the power quality problems due to dispersed generation LV systems are introduced and the necessity of using hybrid filters instead of active or passive filters alone are discussed. The simulations are done with PSCAD/EMTDC for a distribution system with dynamic nonlinear loads and wind turbines, photovoltaic cells and diesel generators and several dynamic nonlinear load without any filters, with usage of just shunt active filter or passive filters and the hybrid filter structure, introduced in the paper. Studying and comparing the waveforms, harmonic contents and THD of the system current with different filter structures mentioned, proves power quality improvement by the applied hybrid filter