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Medium Voltage Direct Current (MVDC) Casualty Power

Description:

 
 

TECHNOLOGY AREA(S): Ground/Sea Vehicles

ACQUISITION PROGRAM: PMS 320 - Advanced Surface Machinery Systems

OBJECTIVE: Develop a lightweight and affordable capability to restore Medium Voltage Direct Current (MVDC) power to zones isolated from generation by damage, to zones between the source and the rest of the system. Portable elements of the capability shall be light enough to be safely handled by a team composed of sailors of size and strength ranging from the 5th percentile female to the 95th percentile male. For a given ship design, the decision on whether to install an MVDC casualty power system will be based on risk and a comparison of the cost and system weight of the MVDC casualty power to the cost and system weight of effectively armoring and protecting the port and starboard buses from damage within a zone.

DESCRIPTION: Casualty power has typically been used to provide loads to specific 440 volt (60 Hz. alternating current) VAC loads through a network of portable cables and through-bulkhead connectors. The system currently used is power limited and very labor intensive.

Future combatant designs are anticipated to implement zonal survivability and selective compartment survivability to the greatest extent practical (ref #1). One challenge is that for small warships, power generation is not generally located in the forward or aft zone due to the inability to locate intakes and uptakes. Furthermore, the beam of smaller warships may not be sufficient to ensure both port and starboard buses in a two-bus system will survive. In these cases, zonal survivability must consider both vulnerability and recoverability. A casualty power system is the means for recovering power to a zone that may be isolated by generation due to battle damage in a zone between it and the zone with generation. A capable casualty power system will enable the crew to recover power to undamaged zones following battle damage.

The envisioned solution would not depend on cable or equipment surviving in the damaged zone, but would employ equipment permanently installed in zones on either side of a damaged zone and portable conductors that the crew could use to “jumper” across the damaged zone. Several redundant portable conductors would be stored in different zones of the ship to ensure a sufficient number of portable conductors survive the battle damage. The casualty power system is intended for MVDC systems (ref #2) with voltages between 6 kV and 18 kV and rated for a current between 300 and 500 amps. The casualty power system should interface (via a mechanism such as coded cable connectors, auxiliary conductors or fiber optic cables) with the machinery control system to enable detection of the connectivity and to limit current to below the system current rating. The envisioned solution should be safe to rig and operate within 30 minutes of the ship’s power system experiencing damage. Minimizing system overall cost and weight are key factors.

A capable Casualty Power System as described here enables recovering power to undamaged zones following battle damage. The alternative would be to either accept the operational risk of losing the capability provided by systems within the unpowered-undamaged zone or by heavily armoring and protecting each of the longitudinal electrical distribution busses (at great cost and additional weight) to enhance their ability to survive battle damage. This would reduce the acquisition costs due to not having to procure new assets to replace those that were not repairable after sustaining damage.

No known research exists on MVDC casualty power systems.

PHASE I: In Phase I, the company must provide a concept for a MVDC Casualty Power system. This concept shall be analyzed to estimate its cost, weight, volume requirements, and the time required by the crew to deploy the system. The company shall perform a hazard analysis and ensure the concept is safe to deploy and operate. The company shall identify technical risks of their concept. In the Phase I Option if exercised, companies will produce draft specifications and a capabilities description for the final components of the system.

PHASE II: In Phase II, the company shall produce a prototype system for testing and evaluation based on the results of Phase I and the Phase II Statement of Work (SOW). This prototype will be delivered at the end of the Phase II. The company shall conduct a test and evaluation program to address the technical risks of operating and integrating the system onboard. This prototype system shall have the full electrical and control system functionality. The company shall update the specifications for the final components of the system. The company shall develop a design practices and criteria manual for the design and installation of the casualty power system for a surface combatant.

PHASE III DUAL USE APPLICATIONS: The company will support the Navy in transitioning the technology to Navy use. The company shall produce first-articles using the specifications for the final components of the system. The company shall conduct first-article testing and any other testing as detailed in the specification for each of the components. The company shall design, construct, and demonstrate a casualty power system using the specifications and the design practices and criteria manual developed in Phase II. The contractor shall update the specifications and design practices and criteria manual to reflect lessons learned. Private Sector Commercial Potential: While casualty power systems generally do not have a direct application to commercial systems, some industries do employ temporary power systems where similar technology may apply. Examples include the mining industry, tunneling machines, and oil industry.

REFERENCES:

  • Doerry, CAPT Norbert, "Zonal Ship Design", ASNE Naval Engineers Journal, Winter 2006, Vol. 118 No 1, pp 39-53. http://doerry.org/norbert/papers/050120ZonalShipDesign.pdf
  • Doerry, Dr. Norbert H. and Dr. John V. Amy Jr., "The Road to MVDC," presented at ASNE Intelligent Ships Symposium 2015, Philadelphia PA, May-20-21, 2015. http://doerry.org/norbert/papers/20150319ASNEISSDoerryAmy.pdf

KEYWORDS: Casualty Power System; portable power cables; temporary power systems; power terminals; medium voltage DC power cables; medium voltage DC power connectors

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