The energy efficient solutions are suitable for upgrades of existing ships as well as for new builds.
Solution One - Economical Operations
Solution One focuses on the energy efficient operation of any ship equipped with direct-driven propulsion machinery combined with a Shaft Generator system, also called Power Take Out (PTO) system. This solution enables the operation of propulsion machinery in combinator mode – variable speed and pitch of the propeller – with the Shaft Generator online and generating power for the ship’s electrical network. This means that the propulsion machinery can be operated at optimal duty points at all vessel speeds. Energy efficiency is improved which results in substantially reduced fuel consumption and decreased environmentally harmful emissions. This solution also enables two-stroke Main Engine installations to be realized with fixed pitch propeller so that a Shaft Generator system can be installed.
Solution Two – Take Me Home
Solution Two is an Auxiliary Power Drive (APD) system that gives propulsion power if the Main Engine is out of operation. This solution essentially enables a ‘Take Me Home’ propulsion operation for product tankers, as well as ensuring a safe return-to-port propulsion for any other ship type by running the WE DriveTM in the Power Take In (PTI) mode. Furthermore, in PTI mode the WE DriveTM system converts Auxiliary Engine power to propulsion power by employing the Shaft Generator as a motor: the electrical power is conveyed where needed thanks to the state-of-the-art Active Front End (AFE) drive technology. Solution Two also includes the functionality outlined in Solution One, covering the energy efficient operation of any ship equipped with direct-driven propulsion combined with a Shaft Generator system.
Solution Three – Boost Mode
Solution Three provides auxiliary power to boost the Main Engine when the application finds itself in demanding situations, such as high bollard pull or sailing in icy condition. This solution can also be used for economical slow steaming with the single Main Engine in a twin-shaft installation. With the Boost Mode solution taken into account during the ship’s design phase, the total operation cost of a vessel can be much reduced compared with traditional propulsion machinery design. This is because the Main Engine size can be optimised to the propulsion power needed under normal conditions. Additional power boost is taken from the Auxiliary Generators as required. This solution enables Boost Mode for any vessel type by running the WE DriveTM in Power Take In (PTI) mode. Solution Three also offers the functionality as outlined in Solution One.
Solution Four – Efficient Power Distribution
Solution Four uses the common DC-link of the WE DriveTM technology, thereby enabling new methods to distribute power in energy efficient and economical ways. Large electrical consumers such as thruster or large compressors can have their dedicated Inverter Units (INU) connected directly to the common DC-link. The WE DriveTM DC-link in this solution is fed from Shaft Generators or Auxiliary Generators. Power can be distributed to a ship’s electrical network, to thrusters, and to propulsion machinery. Solution Four also enables efficient power distribution and controlled short circuit currents, which allows lighter switchboards in marine installations.
Direct-Drive Permanent Magnet Shaft Generator Solutions for Two-Stroke Installations
The permanent magnet rotor is mounted on the intermediate shaft of the propulsion system. Mass and inertia are very low and thus the impact on propulsion system torsional vibration calculations (TVC) remains minimal. No additional bearings are required, thus the propeller shaft system design remains uncompromised. The generator housing, consisting of a compact, feet mounted stator package, including the rotor and intermediate shaft, is positioned on the generator bed in the propeller shaft line and connected via flanges. With the WE DriveTM and Direct-drive Permanent Magnet Shaft Generator (PMSG) in PTO mode, ships electrical power is generated by the fuel efficient two-stroke Main Engine. This means that auxiliary generators can be stopped. As the operating hours of the auxiliary generators are reduced, there will be significant savings in service and maintenance costs as well. The functionality of Solution Three can be achieved with the Direct-drive PMSG. Moreover, with the addition of a mechanical clutch in the propeller shaft line, which enables disconnecting the two-stroke Main Engine, the PTI mode described in Solution Two can be achieved.
Solution Five – Hybrid DC Machinery
Solution Five uses all the energy efficient features of a Hybrid Propulsion Machinery plus a ship-wide DC-link power distribution system. With the DC-link distributing electrical power to all consumers, energy efficiency is increased by up to 20%. The Hybrid DC Machinery concept includes variable speed Auxiliary Generators and Permanent Magnet technologies for the rotating machines. With the ship-wide DC-link power distribution fault currents are kept to a minimum thanks to the precise controls of the dedicated inverter units per consumer. The need for large switchboards and bulky transformers are therefore eliminated, which means greater savings in space and weight as well as far better total efficiency.