1. MVDC Research at The University of Texas Presented by: A. Ouroua For ESRDC Team members at The University of Texas at Austin Philadelphia, September 17, 2008

2. 2 Faculty and research staff: –A. Arapostathis, ECE department : ari@ece.utexas.edu –C. Conner Seepersad, ME department ccseepersad@mail.utexas.edu –K. Davey, Center for Electromechanics: k.davey@mail.utexas.edu –M. Driga, ECE department : driga@mail.utexas.edu –R. Hebner, Center for Electromechanics: r.hebner@mail.utexas.edu –T. Kiehne, ARL/ME department: kiehne@mail.utexas.edu –R. Longoria, ME department: r.longoria@mail.utexas.edu –E. Powers, ECE department: ejpowers@mail.utexas.edu –A. Ouroua, Center for Electromechanics: a.ouroua@mail.utexas.edu –S. Santoso, ECE department : ssantoso@ece.utexas.edu –B. Shutt, Applied Research Laboratory: shutt@arlut.utexas.edu Several graduate students Participants

3. What does a practical system look like? –Which components to use and what are their specifications? Motors, generators, converters type and topology DC generators or AC generators with rectifiers? –How many gen-sets are necessary? Parallel gen-sets –Are DC breakers necessary? Are PCMs enough to mitigate DC faults? –What are representative loads to consider? –Should energy storage be part of the system? Researchers: S. Santoso and A. Ouroua 3 MVDC Research Topics at The University of Texas The UT research program will initially address several questions. These questions define the research topics under considerations.

4. How do we best do load sharing among gen-sets? –What are implications for stability, reliability, and economy? Researchers: A. Arapostathis and M. Driga Can we develop a better power system than medium voltage DC for future ships? –What are alternatives? Researchers: K. Davey, M. Driga, R. Longoria, and W. Shutt What are differences in thermal management between AC and DC systems? –Challenges, if any, need to be identified. –Complete thermal modeling of MVDC system Researchers: T. Kiehne, C. Conner Seepersad, and W. Shutt 4 MVDC Research Topics at The University of Texas

5. How does one protect against DC faults, particularly series faults? –More problematic faults are series faults where connections open but current continues to flow through an arc. This could lead to fire without significant over-current. Researchers: S. Santoso, K. Davey, and A. Ouroua How do signal analysis techniques change with DC systems? –Signal frequency, amplitude, and phase variations, useful in AC systems, not available in DC. What information can be extracted from the residual variations? Researchers: E. Powers and S. Santoso. 5 MVDC Research Topics at The University of Texas

6. What do switching surges look like in a DC system and, based on that, what are the implications for insulation coordination? –Standards for switching surges and insulation are for land-based 60 Hz systems. Need to evaluate impact of DC environment on life and performance of electrical insulation, and consequently, on the reliability of the system. Researchers: R. Hebner and S. Santoso How do we detect the need for reconfiguration in a DC system? –AC-based sensors are not applicable. Researchers: A. Arapostathis, K. Davey, and S. Santoso 6 MVDC Research Topics at The University of Texas