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Compact, Flexible Integrated Power Node Center for Direct Current Distribution

Description:

TECHNOLOGY AREA(S): Sensors, Electronics, Battlespace 

OBJECTIVE: Develop a compact, modular, galvanically isolated, Direct Current (DC) distribution Integrated Power Node Center (IPNC) to supply mission-critical equipment with high-quality, uninterruptible power. 

DESCRIPTION: Future Navy ships will include mission critical equipment with DC interfaces in addition to traditional 60Hz and 400Hz systems. Development of this compact DC power distribution Integrated Power Node Center (IPNC) will avoid costly, custom solutions needed to address each particular load. IPNCs are being employed for replacing existing 400Hz Alternating Current (AC) power systems onboard U.S. Navy amphibious ships and destroyers, which currently use centralized and redundant frequency conversion. Currently the 400Hz power (defined by MIL-STD-1399) is generated in centralized locations and then distributed via a combination of load centers, cabling, Automatic Bus Transfers (ABTs), transformers, and power panels to numerous loads located throughout the ship. This traditional distribution system approach leads to the placement of large and expensive frequency converters at strategic locations onboard the ship and significant distribution components, requiring long cable runs. A more effective and survivable approach would utilize the existing 60Hz distribution system to provide power to compact IPNCs located directly at the load site. The Navy is now moving towards DC distribution, so it is desired to use this approach for new voltages consistent with the “Naval Power and Energy Systems Technology Development Roadmap” [1] to reduce the costs and maintenance associated with centralized conversion and multiple parallel distribution systems for each interface. This innovative compact DC distribution IPNC will enable uninterruptible power using multiple power sources and minimize dedicated energy storage. The only energy storage required will be to hold existing loads while the power system reconfigures. This compact DC distribution IPNC needs to be designed so that only output modules are replaced to accommodate changes in power requirements for upgrades and changes to weapons and sensors during the ship’s service life. The ability to reconfigure IPNC redundant input sources and selectable output voltages will enable a common solution across multiple system loads and ship types. The Navy seeks to develop a compact, modular, galvanically isolated DC distribution IPNC that consists of an enclosure and dual input voltages of 1000VDC and 440VAC, output voltages of 650VDC, 375VDC, 440VAC at 60Hz and 400Hz 3 phase, and energy storage interface modules capable of supporting aggregate loads of up to 300kW that meet DC interface specifications and MIL-STD-1399-300B. The goal is to reduce total ownership costs with reduced acquisition, integration, and maintenance costs associated with separate distribution systems and improve reliability and performance by virtue of simplified and flexible electrical distribution system architecture. The Navy desires a compact DC distribution IPNC whose size, weight, and cost would enable placement in proximity to the load site with minimal ship integration impact. The IPNC should be able to pass through a 26"x66" oval opening and be mountable on a ship’s bulkhead for arrangement flexibility. Power densities for the proposed solution shall have a threshold of two Megawatt per cubic meter with an objective of three Megawatt per cubic meter. Proposed concepts will need to address load survivability during system electrical faults and power interruptions by limiting current and being capable of seamless switching to alternate supply power sources. Compact DC distribution IPNC modules should be able to isolate faults at the load site, without affecting adjacent loads or the rest of the electrical distribution system. Furthermore, these modules must protect the load from upstream anomalies such as high harmonics and input voltage swings exceeding a ±10 percent fluctuation. The goal is to preserve power to the loads such that when the loads have two sources of power, the loss of one source will not cause a power interruption to the load. The compact DC distribution IPNC modules need to be designed with sufficient efficiency to allow air-cooling while maintaining power quality requirements. Recent Navy experiences with power conversion-based systems have demonstrated challenges associated with common mode and line-ground performance under a variety of normal and fault situations. The compact DC distribution IPNC must be compatible with ungrounded naval power systems and therefore be capable of continued operations with the input or output interfaces ungrounded, ungrounded but faulted to ground, or grounded. Internal failures of compact DC distribution IPNCs should not cause adverse line-line or line-ground voltages or currents on the inputs or outputs. Each interface point should have isolation from the other interface points (Input A, Input B, Output X, Output, Y, etc.) to preclude common mode voltages and currents, or line-ground voltage excursions from influencing the other interfaces. Reliability and maintainability is of critical importance as the IPNC is a point of use converter. A failure of the IPNC can result in the loss of mission-critical equipment functionality. The IPNC offered should include concepts with extremely high reliability or modularly to increase the reliability and maintainability. IPNC needs to meet a 20,000 hour mean time between service interruptions. It should be noted, that if a repair requires the unit to stop providing output power, then the repair will be considered a service interruption. Proposed compact DC distribution IPNC module concepts should meet the applicable performance goals converters in MIL-PRF-32272, Performance Specification, IPNC. 

PHASE I: Develop a concept for a compact, modular, galvanically-isolated DC distribution IPNC capable of providing high-quality, high-reliability, uninterruptable power that meets the topic requirements. Demonstrate the feasibility of the concept in meeting Navy needs and transitioning into a useful product for the Navy. Demonstrate feasibility on a component or Lowest Replaceable Unit level. The Phase I Option, if awarded, will address technical risk reduction and provide performance goals and key technical milestones. Phase I will include prototype plans to be developed under Phase II. 

PHASE II: Based on the results of Phase I and the Phase II Statement of Work (SOW), develop and deliver one or more full-scale prototype(s) to the Navy for evaluation. Evaluate the prototype(s) to determine its (their) capability in meeting the performance goals defined in the Phase II SOW and the Navy requirements for the compact, modular, galvanically-isolated DC distribution IPNC. Demonstrate system performance through prototype evaluation and modeling or analytical methods over the required range of parameters. Use evaluation results to refine the prototype into a producible design that will meet Navy requirements. Conduct performance integration and risk assessments; and develop a cost-benefit analysis and cost estimate for a naval shipboard unit. Prepare a Phase III development plan to transition the technology to Navy use. 

PHASE III: Support the Navy in evaluating the prototypes delivered in Phase II and the transition of the technology to Navy use. Based on analysis performed during Phase II, recommend test fixtures and methodologies to support environmental, shock, and vibration testing and qualification. Determine, jointly with the Navy, appropriate systems for integration into Naval Power Systems for the components developed under this SBIR topic for operational evaluation, including required safety testing and certification. Working with the Navy and applicable Industry partners, demonstrate the compact DC distribution IPNC on a relevant shipboard system to support naval power systems. Provide detail drawings, models, and specifications in a defined format; perform an Electrical Safety Device evaluation; and document the final product. Transition opportunities for this technology include power conversion units that power directed energy, specialized loads, and for ship-wide stable backup power systems. Power conversion units such as these can be used by renewable energy plants, private and public utilities, industrial data centers, and a wide range of back-up systems. Low-voltage DC power conversion will become more prevalent as more systems shift to DC. High-power quality units will be required to provide power to these loads. 

REFERENCES: 

1: "The 2015 Naval Power and Energy Systems Technology Development Roadmap." http://www.navsea.navy.mil/Portals/103/Documents/Naval_Power_and_Energy_Systems_Technology_Development_Roadmap.pdf

2:  Doerry, Norbert. "Electrical Power System Considerations for Modular, Flexible, and Adaptable Ships." ASNE EMTS 2014, Philadelphia, PA, May 28-29, 2014. http://doerry.org/norbert/papers/20140412doerryEMTS2014.pdf

3:  "20 -- Request for Information for Electrical Interface Standards for Naval DC Power Systems." http://www.fbodaily.com/archive/2016/11-November/10-Nov-2016/FBO-04323946.htm

KEYWORDS: Integrated Power Node Center; Power Quality; Power Density; Flexible Electrical Distribution System Architecture; Navy Ship DC Distribution; Uninterruptible Power Supply 

CONTACT(S): 

Ewane Etinge 

(215) 897-8907 

ewane.etinge@navy.mil 

Nathan Spivey 

(215) 897-8831 

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