In the North Sea and the Baltic Sea, German federal police use a total of three ships to patrol. They are tasked with surveillance of the sea border into international waters, emergency sea rescue, port inspection and general traffic control, similar to patrolmen on land. While the federal police ships also have diesel propulsion systems, they run on electric power near the coastline.

The ships are used around the clock and the crew has to be able to rely on the on-board technology at all times. The interaction of different electrical components can only function smoothly if clean power is flowing through the grids. This was exactly the problem. The cell phone chargers of the crew regularly broke, the dishwasher or individual computers died and important functions of the bridge electronics were impaired.

This was caused by the frequency converter of the ship’s electric propulsion system. Above a certain gear, it caused harmonics that interfered with the entire on-board electrical system. Therefore, the federal police turned to the experts at Reinhausen Power Quality, who first took measurements on board. The results were astonishing: The standard permits a portion of harmonics of eight percent (five percent is recommended); however, up to 14 percent was measured on board. The Power Quality specialists identified the industrial design of the GRIDCON® ACF active filter as a suitable solution. It is a compact control cabinet solution that is almost tailor-made for the cramped conditions on a ship. To ensure that the swaying and vibrating of the ship does not interfere with the technology, fluctuation dampers were attached under the control cabinet. The GRIDCON® ACF automatically responds to limit value deviations and eliminates the disruptive harmonics. Since it was installed on the federal police ships, the on-board electronics have functioned smoothly.

Container ships and cruise liners have electrical demands that are enormous. Depending on the ship, they can be between three and 16 megawatts, which is about the same as a small city. In most ports, the diesel engines are also running when the ship is at anchor. After all, the crew, guests and, of course, the equipment still need electricity. However, this puts a major strain on air quality in port cities. Therefore, the ports of Hamburg and Kiel are among the first in the world that are turning to shore power supply.

But it is not enough to plug the ship in and turn the diesel engine off. Ship and shore power grids use different voltages and frequencies. Therefore, frequency converters and matching transformers are necessary. Active and passive GRIDCON® harmonic filters from Reinhausen are used to ensure that there is no impermissible grid feedback into public distribution grids via the grid connection. They keep the shore grid clean.