TECHNOLOGY AREAS: Ground/Sea Vehicles, Electronics

ACQUISITION PROGRAM: PMS 320, Electric Ship Program Office

OBJECTIVE: Develop and apply an analytical approach to automatically detect and mitigate electrical faults in MVDC (6-10kV) architectures with - or without - the use of circuit breakers.

DESCRIPTION: The Navy has identified medium-voltage direct current (MVDC) as the ideal long-term solution for the electrical distribution system for future shipboard power systems. Although MVDC systems provide substantial improvement over the current alternating current (AC) which is installed shipboard, the treatment of faults in MVDC is not well understood. Electrical faults in the shipboard power system can cause loss of power to critical loads of the system; detection and control of electrical faults is one of the limiting factors in the development of an all-electric ship.

State-of-the-art technology uses either power electronics to mitigate fault propagation within the electrical zone or multiple sensing devices to measure and predict faults and direct subsequent corrective action. The existing technology for MVAC systems can detect faults in the 4 millisecond range; a MVDC system would require a response within 1-5 microseconds.

This topic seeks the development of advanced fault detection/isolation/coordination methods beyond that of the current state-of-the-art, which can be deployed either with, or without, dedicated system circuit breakers in MVDC systems. In particular these solutions should address the following:

1) Satisfaction of the traditional fault protection elements (ground faults (50/51, 59N, 87N), phase faults (51, 87), under voltage (27/59), sequential tripping, etc., with no protective relays and possibly no circuit breakers.

2) Impact of added responsibility of system protection to the Application Managers of the power electronic distribution system converters.

3) Impact of fault detection speed on solid state circuit breakers. Key area of concern is the impact of cooling of the semiconductors vs. detection and execution speed.

The solution should incorporate both the algorithms related to fault detection, fault isolation and coordination with power system�s two architectures (with or without circuit breakers) and identify the advantages/disadvantages of each approach.

PHASE I: Demonstrate the feasibility of an innovative approach to automatically detect/mitigate faults in the 1-5 microsecond time period for MVDC systems and address the impact the detection / execution speed on both the cooling requirements for the power electronics devices and their embedded control systems. Identify and define new measures to achieve the traditional protection system elements with this new protection system paradigm. Develop an initial conceptual design and establish performance goals / metrics to analyze the feasibility of the proposed solution.

PHASE II: Finalize the design concept from Phase I and fabricate a diagnostic test bed prototype. In a laboratory environment, demonstrate the ability to make repeatable decisions based on relationships between measured and estimated data. Develop testing procedures to measure the effectiveness of the system and develop a plan for an installation and testing onboard ship. As appropriate, develop the interface specifications and provide a detailed plan for software certification and validation.

PHASE III: Working with the Navy, install and test at the Land Based Engineering Station test facility. Provide detail drawings and specifications. Technology will have potential to transition to all future US Navy platforms that require high energy weapons using MVDC architectures.

PRIVATE SECTOR COMMERCIAL POTENTIAL/DUAL-USE APPLICATIONS: Large-scale application of renewable energy sources � such as wind or solar � will require the management of DC transmission systems. These systems are still under development by the Department of Energy, but fault control will be a critical component. Fault detection algorithms capable of quickly isolating a fault can dramatically improve the life of the system components that are subjected to large stresses during the fault periods.

REFERENCES:

1. "Shipboard Electric Power Distribution: AC Versus DC Is Not the Issue, Rather, How Much of Each Is the Issue"; LCDR John V. Amy Jr. PhD, Mr. David H. Clayton and Mr. Rolf O. Kotacka; All Electric Ship 98 Conference.2nd ed., vol. 3, J. Peters, Ed. New York: McGraw-Hill, 1964, pp. 15-64.

2. C. Wood and P. Clark. FADES: An Expert System for Fault Analysis and Diagnosis. TIRM 87-024, Turing Institute, 1987.

3. Next Generation Integrated Power Systems (NGIPS) Roadmap:
https://www.neco.navy.mil/synopsis_file/N00024NGIPS_Technology_Dev_Roadmap_final_Distro_A.pdf.

4. http://en.wikipedia.org/wiki/Renewable_energy.

KEYWORDS: Fault Detection; Fault Mitigation; MVDC; MVAC; Faults.

** TOPIC AUTHOR (TPOC) **

DoD Notice:   Between November 12 and December 7, 2008, you may talk directly with the Topic Authors to ask technical questions about the topics. Their contact information is listed above. For reasons of competitive fairness, direct communication between proposers and topic authors is not allowed starting December 8, 2008, when DoD begins accepting proposals for this solicitation.

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