Flicker disturbances in steel manufacturing plant: A case study

A steel manufacturing company was in the process of opening a new plant for of gratings production. Since they had experienced several flicker and unbalance problems in the past, which is a typical situation for this kind of manufacturing installations, a preliminary study to avoid such kind of problem both in the new manufacturing site and in the network around it has been carried out by the authors of this paper. Flicker and unbalance disturbances in the original site were mostly due to the installed welders which have a highly intermittent working cycle. The same welders were going to be installed in the new plant. After a first step dedicated to the characterization of the network in the new plant neighborhoods, the following activities has been: the evaluation of the technical feasibility of the project, the determination of the electric installation main features for welder power supply and for auxiliary machine power supply. Then it has been possible to develop and propose to the industry management different appropriate solutions aiming to avoid flicker and unbalance problems. The solution which has been adopted has been evaluated on the basis of a technical-economical analysis aiming to find the most cost-effective mitigation measure. The paper summarizes the general approach to the problem, work methodology and outlines mitigation solution proposed and adopted in particular by providing a detailed description of the technical-economical analysis process carried out in the optimal solution assessment.