Erfan Sahraei - Department of Electric Power Engineering, Hadaf Institute of Higher Education, Sari, Iran
Abdolhossein Tahani - Department of Electric and Computer Engineering, Babol University of Technology, Babol, Iran
Mohammad Yazdani-Asrami - Department of Electric and Computer Engineering, Babol University of Technology, Babol, Iran

The main purpose of this article is to employ the passive filters for maximization of the loading capability of transformers and current carrying capability of cables under non-sinusoidal load currents. To achieve this goal, a hybrid passive filter, which consists of a certain combination of a shunt passive filter (SPF) with a series passive portion is proposed. Particle swarm optimization (PSO) algorithm is used to find the optimal sizing of parameters of the hybrid passive filter in order to reduce both harmonic voltages and harmonic currents in the studied system to an acceptable level, which is lead to maximization the Derating Factor (maximum permissible current carrying or loading capability) of transformers and cables. According to IEEE Standard 519, the total harmonic distortions of the voltage and current measured at the point of common coupling (PCC) are taken into account as main constraints of the proposed approach. The optimal design of the hybrid passive filter and its feasibility are compared with the C-type passive filter in the two same filter design approaches based on maximization of the classical power factor (PF) and maximization of the power factor considering transmission line (PFe). Finally, the presented numerical results show that the hybrid passive filter has a better performance and provides higher current carrying capacity of cables and higher loading capability of the transformer under non-sinusoidal conditions when compared to C-type filter. Two numerical case studies are presented to demonstrate the proposed approach

Optimal filter design, Loading capability, permissible current carrying