Diesel Electric Propulsion for Liftboat a NES ‘Belt & Braces’ Solution

By George Backwell at August 24, 2013 04:37
Filed Under: drive systems, Offshore

A diesel electric propulsion system from a fairly new company based in Bergen, Norwegian Electric Systems (NES), is to be installed in the self-elevating work and accommodation barge ‘GMS Enterprise’ now under construction in the Middle East by Gulf Marine Services (GMS). The propulsion system for the DP2 rig is NES’s proprietary Quadro Drive® VFD, which gives an exceptional level of safety redundancy with its Black Out Safety System (dubbed B.O.S.S.).

Quadro Drive®
The Quadro Drive®, explains the manufacturers, is specially designed for ship installation and meant to set the standard of next generation propulsion converters; there is no need for a large transformer, as there is just one unit to install, making installation much easier and less expensive.

Quadro Drive® typology: Rendering courtesy of NES

A modular-based system is the cornerstone of the Quadro Drive® which gives possibilities for interchangeable parts, and an option of derating the drive if one module fails so the vessel can avoid off-hire time. Also worth mentioning is a drive interface which allows availability for  all common field-buses including Modbus and Profibus.

The Active Rectifier yields the possibility of regenerating the energy from the propeller and shaft back to the grid. The power factor is always unity, so the grid’s capability is fully utilized. The result is a flexible and dynamic propulsion system, focusing on a high performance energy chain from the diesel motor (in this newbuilding, according to GMS, four 1600 kW Wärtsilä 8L20 gensets) to thrust on the propellers.

B.O.S.S.® (Black Out Safety System)
The main philosophy of DP2 and DP3-class requirements is that the system shall handle one fault, whatever this fault may be, and still be able to maintain the position of the vessel. B.O.S.S.® supervises the complete electrical propulsion system, to ensure that the main philosophy of the DP-class is applied throughout the complete electrical system.

B.O.S.S. is the front line of defence against unexpected situations and abnormal behaviour of the main electrical components within the vessel’s power plant. The functions of the B.O.S.S.® system are integrated in the MSB and propulsion drives, collecting necessary information and performing the corrective actions.

B.O.S.S. features:

  • Full control of available power
  • Supervision of frequency and voltage
  • System is implemented throughout generators and  Quadro drive.
  • Rapid torque reduction to reduce output power in situations where a total black out might occur.
  • Integrated in Main Switch Board
  • Two independent systems if bus-tie breaker is ‘Open’

GMS Enterprise is an 83-m LOA E-Class self-propelled, self-elevating accommodation DP 2 jackup barge, capable of providing well service, construction, installation and accommodation for up to 150 persons. A 400-tonne crane is fitted and the vessel can operate in water depths of up to 80m.

GMS E-class liftboat: Photo courtesy of Gulf Marine Services

Launch from the GMS shipyard is scheduled for December 2013 and apart from the steel work, which comes from China, the modified 'Gusto' jack-up is being built entirely in Abu Dhabi, with the detailed design, jacking system and outfitting completed by GMS’ own in-house team and a local labour force.



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