Background
Westfälische Drahtindustrie GmbH (WDI) is among the largest producers of steel wire products in Europe. At their Construction Steel site in Saltzgitter, Germany, they manufacture cold-ribbed reinforcing steel (CR) in rings and coils, as well as structural steel mesh. Manufacturing is carried out using welding machines from Schlatter Group, a world leader in plant manufacturing for resistance welding machines and weaving machines for special applications.
Challenge
The manufacturing of construction steel consumes electrical power in a very irregular and abrupt manner and was causing a lot of voltage variations. This in turn was causing flicker throughout the plant. The main challenge was that a lot of switching transferred to the electrical grid and negatively influenced the power quality of nearby industries and houses. This in turn led the utility owner to force WDI to take action to fix the issue, or else lose its license to operate. Flicker will vary with the production type running, and failure to mitigate the problem would have meant that the plant would not have been compliant with regulations.
Solution
A solution consisting of seven Comsys ADF P300W-300/690 liquid cooled active harmonic filters was delivered to WDI in cooperation with Schlatter AG, who also delivered the welding lines. The total installed compensation capacity was 2100A at 690V.
Result
Flicker is measured in short-term perceptibility (PST) and long-term perceptibility (PLT). Prior to compensation, the flicker levels were at PST 2.0 and PLT 1.4. The installation was carried out in 2011 and is still running with only minimal correction and repairs, as well as some upgrades to improve efficiency. As a result, PST has been reduced from 2.0 to 0.6, power consumption was lowered 25-40% thanks to reduced reactive power, and voltage dips on the 20 kV rail were lowered from around 500V to around 100V.
