With a GE Ship’s Electric Grid at 11 kV and >130 MVA, this is highly-efficient, flexible power and propulsion at scale.

Challenge

The Queen Elizabeth Class, HMS Queen Elizabeth and HMS Prince of  Wales, are the UK Royal Navy’s new aircraft carriers. The ships, more than three times the displacement of the Invincible Class they replaced, represent a step change in both size and capability.

This scaling-up came with significant energy demands, both for propulsion and for the ship’s intense operational mission systems, as well as crew and vessel services. The aircraft carriers would need a way of providing all this power as efficiently and safely as possible.

GE Power Conversion set out to design a configurable, scalable and integrated Electric Ship power architecture, pulling through proven equipment from other naval and commercial platforms, to help minimize cost and risk.

Selection of an Electric Ship Solution
 

The Queen Elizabeth Class Carriers are the first RN ships to have been designed from the outset as an integrated full electric propulsion (IFEP) vessel, without legacy constraints, allowing us to help maximize the benefits of an Electric Ship. But what are they?

The electric architecture design philosophy focused on :

• Superb flexibility : the ability for any power source to supply any load and functionality, through a microgrid of distributable power.
• Availability : scalable power management through graceful network degradation, rather than having to build in ‘redundancy’ (over-sizing the power system).
• Survivability : considerable layout flexibility providing protection through separation of equipment.
• Efficiency : only draws on the power it needs, reducing fuel consumption and helping to stay on mission for longer.

The Design Process – Success through Collaboration
 

GE’s Power Conversion business has been involved in the Aircraft Carrier project from the early competition phases through to design, manufacture, test, installation, commissioning, trials and support.

After the formation of the prime contractors’ Aircraft Carrier Alliance (ACA), Power Conversion was selected as preferred power and propulsion partner for the Electric Ship, including HV Electric Grid, Propulsion and System Integration elements of the power and propulsion systems.

The formation of a formal Power & Propulsion Sub-Alliance in 2007 between Power Conversion, Thales, Rolls-Royce and L3, significantly facilitated the vital value engineering,design maturity, trade-offs, interfacing and integration work ahead of the manufacturing phase. This was instrumental in project success and helping to de-risk the program.

Solution

Twin island arrangement, with 50% of the propulsion and services supplied fwd, and 50% aft.

HV power and propulsion system arrangement:

• 2 x gas turbine (GT) & 4 x diesel generator (DG) electric alternators
• 4 x 11kV switchboard sections
• 4 x 20MW multi-phase Advanced Induction Motors (AIM)
• 4 X 20MW PWM multi-phase VDM25000 converters and 12 transformers
• 13 x ship’s service transformers
• 3 x harmonic filters
• 2 x shore supply power connections
• Power & Propulsion System control panels
• Electrical power control and management system
• System integration of GEPC Ship’s Electric Grid and with other alliance partners
• HV load bank for all setting to work and commissioning for the IFEP

Solution Benefits and Outcome :

• Quiet and resilient, shock-capable electrical drive trains
• Physical separation to suit build and survivability, connected only by electrical network (not rigid drive shafts).
• Enhanced availability, reliability and maintainability : Inherently robust power and propulsion plants.

Flexible, Frugal and Futureproof : 

• Lowest number of installed prime movers compared with mechanical or hybrid drive ship systems.
• Easily adaptable to changing mission profiles, and future integration of low/zero emission power sources.
• Through-life cost savings in fuel and maintenance, due to running optimum number of prime movers at optimum loadings to match power demand.
• Large amounts of installed electrical power can accommodate significant future increases in combat system loads such as high-energy weapons and radar, with minimal impact.