TECHNOLOGY AREAS: Ground/Sea Vehicles

ACQUISITION PROGRAM: PMS 320, Electric Ship Office

OBJECTIVE: Develop a compact, high-speed, electrical circuit isolation device for use in medium voltage, direct current (MVDC) architectures thereby enabling the use of MVDC architectures with acceptable survivability, reliability, efficiency, power density and cost.

DESCRIPTION: Future ships will have significantly increased power demands compared to ships of similar size constructed today. To enable this, advanced architectures such as MVDC will be needed to effectively move generated power to both propulsion and advanced weapons and sensors. Integrating large power sources and loads via a common DC bus simplifies the interface control and hardware requirements, eliminating the need to synchronize frequency and phase in paralleled sources and in transient event recovery.

Following on concepts developed for the Navy�s low voltage DC architecture, referred to as the Integrated Fight Through Power (IFTP) system, it is anticipated that future MVDC architectures will control system currents via source power converters or advanced circuit interruption devices, such as solid-state or hybrid breakers. By combining advance protection concepts and this ability to quickly control/interrupt source currents, there is a decreasing need to incorporate fault interruption capability within each node of the MVDC architecture. To support a fault clearing response that minimizes the system impact, a means of isolation is still required at the zonal nodes of the MVDC architecture. Utilization of a high-speed isolation device would, in theory, provide the functionality to isolate a faulted circuit. However, the Navy does not have a device to perform this MVDC isolation function. Additionally, the Navy is not aware of any direct commercial solutions to this MVDC isolation application. It is assumed that without additional research and development such MVDC isolation would be implemented via modified commercial MV switchgear technologies, such as MVAC vacuum circuit breakers, MVDC circuit breakers, solid-state breakers, hybrid breakers and power converters. However, each of these solutions has technical application issues that result in an unacceptable, or at least a sub-optimal, solution for a MVDC isolation device.

This topic seeks non-traditional and innovative approaches to the development of a compact and efficient circuit isolation device to enable MVDC architectures with acceptable power density and power continuity. MVDC architecture applications include voltages ranging from 5-10kVDC and currents ranging from 1-10kA steady-state. The objective is to develop such a device with the following features:
o Power volumetric densities exceeding 30MW/m3,
o Opening response times less than 1msec,
o Steady-state resistance less than 0.5mohms, and
o Connected/isolated cycles of 5000 or greater without failure.

The device is not expected to interrupt current, but if interruption capability exists that should be stated. The device is not expected to make current, but if making current capability exists that should be stated. Additionally, considerations should be made to ensure that contact bounce-based arching from shock events is considered in mechanical switch solutions.

PHASE I: Demonstrate the feasibility of a circuit isolation device(s) for use within MVDC applications with voltages ranging from 5-10kVDC and currents ranging from 1-10kA steady-state. As a means of demonstrating feasibility, provide a preliminary design of a 10kVDC 4kA circuit isolation device. Establish performance goals and metrics to analyze the feasibility of the proposed solution. Provide a Phase II development approach and schedule that contains discrete milestones for product development

PHASE II: Develop, demonstrate and fabricate a prototype as identified in Phase I. In a laboratory environment, demonstrate that the prototype meets the performance goals established in Phase I. Conduct performance, integration, and risk assessments. Develop a cost benefit analysis and cost estimate for a naval shipboard unit. Provide a Phase III installation, testing, and validation plan.

PHASE III: Working with government and industry, fabrication of shipboard module to be provided to Navy for transition into commercial and military MVDC power applications. Conduct extended testing and verify performance.

PRIVATE SECTOR COMMERCIAL POTENTIAL/DUAL-USE APPLICATIONS: This technology would be applicable to any future Commercial MVDC system.

REFERENCES:
1. Doerry, Norbert. "NGIPS technology Development Roadmap." 30 Nov 2007. Naval Sea Systems Command.

2. Amy, John, (2005) "Modern, High-Converter-Populations Argue for Changing How to Design Naval Electric Power Systems," presented at IEEE Electric Ship Technologies Symposium, July 25-27, Philadelphia, PA.

3. IEEE P1709, "Recommended Practice for 1 to 35kV Medium Voltage DC Power Systems on Ships."4. Hegner, H; Desai, B. "Integrated fight through power." 25 July 2002, IEEE Power Engineering Society Summer Meeting.

KEYWORDS: circuit protection; switch; MVDC; electrical; IFTP; NGIPS

** TOPIC AUTHOR (TPOC) **

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