On the compensation of non‐active current components of three‐phase loads with quickly changing unsymmetry

Some types of loads, like arc furnaces, present a special challenge to compensation strategies. They vary quickly and have a very high rated power. For example the arcs of an arc furnace are not burning continuously especially when starting the melting process. This causes variations of the line voltage with frequencies well below the line frequency commonly known as voltage flicker. Because of cost efficiency the energy storage capability of compensators for the mitigation of voltage flicker effects can still only be small compared to the energy taken by the arc furnace during one period of the line voltage. This paper discusses the use of a compensation tool which quickly detects negative sequence current components in comparison to the calculation of an equivalent conductance using the so‐called FBD method (Fryze‐Buchholz‐Depenbrock method). Simulations are used to demonstrate the advantages and disadvantages of the tool for detecting negative sequence current components. It is shown that the quick detection and compensation of negative sequence current components can reduce the amount of voltage flicker considerably.