Danfoss used an Active Harmonic Filter to compensate the THD of their installed 960 kW of VFDs for thruster and refrigeration compressor on the fishing vessel Gitte Henning #8. The AHF ensured to keep the installation within class requirements. Read more at:
STATCOM AHF Reduces Flicker
Due to an increased usage of the local grid, a stricter limit of flicker emission became a necessity. One of the largest steel wire producers in Europe managed the problem by installing a STATCOM solution and lowering their flicker emissions.
The processing plant is the largest steel wire producer in Europe, part of a German industry group founded in 1856. The company produces steel reinforcement mesh grids. The production line is made up of various welding equipment, including spot welders from Schlatter AG. As is the case with all powerful spot welders, the abrupt current consumption causes voltage variations, which in turn produces flicker.
Due to expansion of the area and increased amount of renewable energy sources, it became necessary to lower flicker contribution. Early reference measurements showed flicker levels up to Pst 2 and Plt 1.4. A futher
complication the the case was caused by a lot of switching activity in the surrounding electrical grid. This contributed to higher background flicker and making measurements more difficult. Finally, depending on the production type currently running, the flicker will vary.
STATCOM by AHF – the Solution
The solution was offered in cooperation with Schlatter AG, who also delivered the welding lines.
A STATCOM solution consisting of 7 300/690W water cooled active harmonic filters was installed. The nominal installed power is 2.5 MVAr. The fully water cooled STATCOM follows the load dynamically. Neither changes in the production nor newly installed equipment leads to any need for adjustment of the compensation system. The AHF units were installed via a dedicated transformer and use their own medium voltage measurement point.
The STATCOM solution reduced the flicker level to Plt 0.6. Reduced reactive power lowered current consumption 25-40%. Voltage dips on the 20 kV rail were lowered from around 500V to around 100V.