Comparative evaluation of common passive filter types regarding maximization of transformer's loading capability under non-sinusoidal conditions

This study aims to comparatively evaluate the widely known five passive harmonic filters as single-tuned, double-tuned, triple-tuned, damped-double tuned and C-type ones by regarding their contribution on the loading capability improvement of the transformers under non-sinusoidal conditions. For the comparative evaluation, the studied filter types are optimally designed to minimize the harmonic loss factor index, which is defined as a tool to determine the transformer's permissible loading capability under non-sinusoidal current conditions in IEEE C.57.110 standard. According to the harmonic distortion limitations and the reactive power compensation level recommended in IEEE 519 standard, the individual and total harmonic distortions of voltage and current at point of common coupling and displacement power factor are considered as constraints of the studied optimal filter design problems. Whales optimization (WO) algorithm, which has recently been introduced in the literature, is used to find the optimal filter solutions. To show the validity of the obtained optimal filter designs, the results are also provided via Particle Swarm Optimization (PSO) algorithm. The simulation results show that the studied filters can be ranked from the best to worst as triple-tuned, damped double-tuned, double-tuned, C-type and single-tuned ones in terms of their performance on the transformer's loading capability improvement. It is also seen from the simulations that the results of WO and PSO algorithms are very close to each other, and WO algorithm achieves optimal design solutions with considerably lower iteration numbers and run times.