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August 22, 2008

Lübeck commissions Germany's first plug-in power supply for ships

More ports worldwide are following the same trend set at U.S. West Coast ports, such as Los Angeles, that see plugging ships into shoreside power as critical to cutting emissions.

Siemens Energy and regional energy utility Stadtwerke Lübeck have commissioned Germany's first shoreside power supply system for merchant ships. Installed at the port of Lübeck's Nordland dock, it provides ships with an environmentally friendly and economical electrical power supply via the local medium-voltage system while berthedt. The system has been built for the Swedish-Finnish paper, packaging and forest products company Stora Enso and the first user is Swedish shipping line Transatlantic, which operates the paper-carrying ferries Transpaper, Transpulp and Transtimber.

The Transatlantic ships have 400-V/50-Hz on-board systems. They had already been retrofitted to used shoreside power at Kemi in Finland and Gothenburg, Sweden. The ships have a cable drum with plug-in connector, a control system for the coupling process and a transformer on board.

In Lübeck, Siemens installed the matching connecting point on the dock. Stadtwerke Lübeck created the connection to the medium voltage network as well as the connection between the transformer substation and the 6-kV socket outlet. Stadtwerke Lübeck installed a 10-kV switchgear for connection to the utilities and a 6-kV switchgear for connection to the on-board system.

A cast-resin insulated transformer rated at 2500 kVA was also installed in a concrete substation on the harbor site to separatie the two networks electrically. Another component of the shore side connection is a smaller concrete substation with a 6-kV outlet at its side enabling power to be obtained from the dockside via the plug-in connector of the ship.

"As soon as the ships obtain the power they need via our shore side power supply system, they can switch off their diesel generators while they're berthed in port. These diesel generators not only produce electrical power but also exhaust emissions, soot, particulate matters and noise, so in this way these ships will help to reduce 'harbor smog' which is becoming an increasingly serious environmental problem in many port cities," said Ralf Christian, CEO of the Power Distribution Division in the Siemens Energy Sector.

The Lübeck shore side power supply system operates at 50 Hz only because the on-board system of the Transatlantic ships uses the same frequency as the local power supply network. However, about 80 percent of the world's have a 60-Hz on-board system. If these ships are to be supplied with shore side power, the frequency would have to be adapted.

For this purpose, Siemens has developed the Siharbor cold ironing system, which enables on-board systems of ships and power supply systems on land to be connected together despite different voltages and frequencies.

The core element is the Siplink (Siemens Multifunctional Powerlink) system, in which two converters are connected together by a DC link and are each connected to one power supply network. In this way, Siplink can not only feed a separate network from a distribution network but can connect power supply systems with different parameters and interconnect them.

For example, at its shipyard in Flensburg, the Flensburger Schiffbau-Gesellschaft (FSG) utilizes Siplink when installing a vessel's on-board electrical system. Siplink provides a 60-Hz power supply with adjustable voltage, and can also be used later as a test load when checking the electrical system. Just as with the Siharbor solution, Siplink can link the electrical system of a ship while it's in the shipyard to the local power supply grid.

To use the Siemens solution, both the harbor and the ship must be specially equipped with, among other things, a plug-in connection system. After connecting the plug-in connector of the ship, the automation system installed on shore can automatically initiate the start up of the shore side power supply system. The user dialog for this is conducted from the ship. The ship's power supply is not interrupted. Siplink is self-synchronizing and takes over the power supply within a few minutes. The diesel generators of the on-board power supply can then be shut down and the complete on-board network is supplied in an environmentally friendly way from the shore side power supply system.

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