Analytical estimation in APF sizing for networks of analogous loads (Estimation of overall THD)

Abstract

nowadays, most of the power electronic loads or nonlinear loads like as computers in offices, electronic lighting ballasts in hospitals or universities, faxes, photocopier machines, advanced electric drive systems, etc. represent the main sources of harmonics which produce a huge negative effect on the overall electric system, and this leads to increase the losses more and more. Each type of previous nonlinear loads is operating in synchronism like as group of computers in any company or university and then they have the same analogous Fourier distributions regardless of the magnitude of each individual harmonic of all current's components. A shunt APF is used to filter the harmonics, in order to protect the electric generators and power cables against their negative side effects. In this paper, an overview of the synchronism operation of these loads is explained, and estimation for a fast sizing of the shunt APF is explained, depending on labeled values of THD of individual loads connected on any feeder on the power system utility, Keeping on all harmonics removal, and based on mathematical procedures without need to on-site measurements.