Harmonic and Distributed Generation Interaction Issues in the U.S. Navy All-Electric Ship Program

1. Harmonic and Distributed Generation Interaction Issues in theU.S. Navy All-Electric Ship Program Center for Advanced Power Systems Florida State University Dr. Thomas Baldwin, P.E. Power Systems Conference 2002 Impact of Distributed Generation

2. Motivation Drivers • Newer Naval ships require significantly larger amount of energy and power (much greater than commercial ships) • Pulse weaponry • High-tech, high-power military loads • The need for higher installed power places demands on: • Energy conversion • Power delivery system Prompting a move to a common energy / power platform • Military requirements dictate the need for • Low signatures (enemy identification) • Non-interference (compatible with military operations) • Damage tolerance (recovery and sustainability) Power Systems Conference 2002 Impact of Distributed Generation

3. System Level Performance • Electric Ships are more than electric-drive systems • Includes power generation, distribution, and controls • Other loads: • Pulse-power and pulse-energy weaponry • Electro-magnetic assistance launch (EMAL) • Communication, computer, radar, and sonar • Hospitality and service loads • Power system design must be reliable and survivable • Graceful degradation • Operational after attack damage • USS Cole - negative experience for the US Navy Power Systems Conference 2002 Impact of Distributed Generation

4. System Philosophy • Currents • ac – conventional technology, common machines • dc – electronic loads, energy storage, fuel cells • hybrid – best of both worlds? • Issues of controllability • stability • harmonics • protection • Challenges • conversion between current forms • losses Power Systems Conference 2002 Impact of Distributed Generation

5. System Philosophy • Distribution system topologies • radial network • traditional method for general electrical loads on ships • loop-radial network • improvement to reliability and handling pulse loads • zonal network • mesh (open or closed) network divided into controllable zones • power electronic devices (PEBBs) couple the zones together • controlled power flows, frequency/voltage conversions, filtering Power Systems Conference 2002 Impact of Distributed Generation

6. Vision Electrically Reconfigurable Ship All Electric Ship Integrated Power System • Technology Insertion • Warfighting Capabilities • Automation • Reduced manning • Eliminate auxiliary systems • steam • hydraulics • compressed air • Electric Drive • Reduce number of Prime Movers • Fuel savings • Reduced maintenance Main Power Distribution Propulsion Motor Prime Mover Motor Drive Generator Power Conversion Module Ship Service Power Electric Ship System Concept Increasing Affordability and Military Capability Courtesy, ONR Power Systems Conference 2002 Impact of Distributed Generation

7. POWER GENERATION MODULE FUEL CELL TODAY ZONAL ELECTRICAL DISTRIBUTION SYSTEM POWER ELECTRONIC BUILDING BLOCK SHIP WIDE ELECTRICAL OUTAGE COMBAT ELECTRONICS SHUT-DOWN RECOVERY OF SUPPORT & THEN COMBAT COMBAT READINESS CASUALTY Ship Service Converter Module (SSCM) SOURCE LOAD TIMELINE MILLI-SECONDS SECONDS MINUTES + Ship Service Inverter Module (SSIM) PEBB DETECT FAULT ~80 MICROSECONDS 2-8 SAMPLES COMBAT SYSTEMS STAY ON LINE Power Port Power Port FUTURE Control Ship Service Converter Module (SSCM) SYSTEM CONTROL ISOLATION OF DAMAGE/ RECONFIGURE ELECTRIC PLANT COMBAT READINESS CASUALTY ~ 1 MICROSECOND PER SWITCH TIMELINE < 100 MILLI-SECONDS Reconfigurable, Survivable Power Systems Challenges: • Power Density • Energy Density • System Efficiency • Resource Management and Control Courtesy, ONR POWER DISTRIBUTION MODULES Power Systems Conference 2002 Impact of Distributed Generation 6.301.280

8. PDM-1 PDM-1 PDM-1 PDM-1 PDM-1 Propulsion Motor Module PGM-4 PDM-4 PGM-4 PGM-4 Propulsion Motor Module PDM-4 PGM-4 PDM-1 PDM-1 PDM-1 PDM-1 PDM-1 Integrated Power System Approach Power Generation Module Power Distribution Module Flexible and Scaleable Power System Power Systems Conference 2002 Impact of Distributed Generation

9. Technology: PEBBs • Power Electronic Building Blocks • may consist of ac/ac, ac/dc, and dc/dc converters • performs multiple power system functions • power flow control • voltage transformation • network protection • serves as interface and controller • between distribution zones • to energy storage systems, fuel cell generation • to pulse loads (e.g., EMAL, pulse weapons) Power Systems Conference 2002 Impact of Distributed Generation

10. Technology: Propulsion Drives • Propulsion Drives • Move to propulsion pods • pm synchronous machines • ac induction motors • dc homopolar motor • Drive technologies • ac / dc-bus / ac converter • ac / dc converter • dc / dc converter • cyclo-converter Power Systems Conference 2002 Impact of Distributed Generation

11. Harmonic Noise • Well-known fact that converters and drives inject harmonic signals onto the electrical network • supply-side noise can impact sensitive loads and network control and protection • load-side noise can impact machine performance, insulation life, and mechanical bearings • Cyclo-converters • also introduce inter-harmonic signals as a function of the input and output frequencies Power Systems Conference 2002 Impact of Distributed Generation

12. Typical Harmonic Levels Cyclo-converter at zero speed, showing classical harmonics Power Systems Conference 2002 Impact of Distributed Generation

13. Typical Harmonic Levels Cyclo-converter at medium drivespeed, illustrated interharmonics Power Systems Conference 2002 Impact of Distributed Generation

14. Harmonic Sensitivity • Sensitive ship loads • radar systems, communication systems • computer controls for weapons and navigation • technical issues • military computer systems have long restart times • loss of critical loads are not acceptable to the Navy • Currently used harmonic mitigation methods • motor-generator sets • isolated generation and distribution systems • isolating UPS (dc link) Power Systems Conference 2002 Impact of Distributed Generation

15. Harmonic Mitigation • Typical Navy ship builder’s experience • Design conversion of one class of submarines to an all-electric design • electric drive reduced propulsion drive system size and weigh – eliminated the mechanical gearbox • power system required extensive harmonic filtering • consequence: overall vessel design length increased by 10 feet • Novel Course of Action • Harmonic zones • some zones are permitted to operate with high levels of harmonic distortion • zones are separated by PEBB units • research of zonal approach is in the initial phase Power Systems Conference 2002 Impact of Distributed Generation

16. CAPS Harmonic Research Program • Challenge: increasing prevalence of solid state switching converters on a closely coupled AC or DC network that may create problems of harmonic distortion, resonance between system components and system stability • Objective: characterize harmonic levels in an (isolated) integrated power system, which has yet to be built, and address any potential problems prior to construction • Task: • investigate the effects of harmonics in ship power components and loads, looking at parametric studies, hypothetical operating situation, and new technologies for power conversion, control and filtering • Analyze zonal distribution system with mixed levels of harmonic distortion Power Systems Conference 2002 Impact of Distributed Generation

17. CAPS Harmonic Research Program • System and model verification initiative • USCG Healy • EMTDC studies • on-board harmonic measurements during maneuvers • real-time digital simulation of primary propulsion system • Parametric studies on zonal distribution system • Simulation studies of converters, drives, and PEBBs • Time-domain computer simulations • Hardware-in-the-loop tests on prototype power-electronic equipment Power Systems Conference 2002 Impact of Distributed Generation

18. Simulation & Modeling • Simulation of tightly-coupled power systems with power electronics and weak generation sources • In the utility world, power system problems have been approached through simulation and modeling • initially with scale analog models • in the last 30 years with digital modeling • Ship propulsion systems are modeled digitally • using techniques developed primarily for mechanical and control system • The heavy use of power electronics in ship systems creates a need to understand the system performance Power Systems Conference 2002 Impact of Distributed Generation

19. USCG Healy Studies Ship power system modeling • model development (Aug 2000-June 2001) • propulsion load models of ship hydrodynamics • propulsion drives, motor, and control system • generation control and dynamics • model verification (comparison with CG results)(Apr 2001-Nov 2001) • performance design criteria • ship design-phase simulations • recorded data from ship data acquisition system Power Systems Conference 2002 Impact of Distributed Generation

20. USCG Healy Program Ship’s one-line diagram Power Systems Conference 2002 Impact of Distributed Generation

21. Real Time Modeling • Utility industry uses real time digital simulation for hardware-in-loop testing of control systems and protective devices • CAPS is acquiring a commercial real time simulation system sufficient to model a mid-sized ship system • R-T simulator will be evaluated for performance with closely-coupled systems by studying the USCG Healy system • Structure a research program focused on advancing the real time simulation capability Power Systems Conference 2002 Impact of Distributed Generation

22. Power Test Bed • CAPS is combining real-time simulation with power component testing in a hardware-in-the-loop facility to create a unique testing environment that will: • provide capability to control source and load characteristics for hardware under test to emulate an actual power system condition • provide dynamic response to equipment under test • provide wide range of voltages & frequencies • provide the capability to create system configurations that model new designs and applications • provide easy reconfiguration capability for diverse equipment under test Power Systems Conference 2002 Impact of Distributed Generation

23. G G = = = ~ ~ ~ CAPS Test Facility 115 kV Transmission Lines Gas Turbine Generators (2) 2.5 MW To Perdom Generation Plant To Hopkins Generation Plant (2) 30/40/50 MVA Transformers Levi Steet Substation 12.47 kV Main Experimental Bus 5 MVA Transformer 12.47kV / 750 / 1500 3.5 MVA Transformer 12.47kV / 4160 Utility System CAPS System HTS Substation Feeders to NHMFL Feeders to Innovation Park 5 MW Converter 4-Q Operation FCL DC Experimental Bus Adjustable: 500 to 2000 V 5 MVA Variable Voltage / Frequency Inverter 2 MW Bi-Directional Chopper 4160 V AC Experimental Bus BWX 100-MJ SMES Magnet Energy Storage S 2.5 MVA Transformer 4160 / 450 V C C MCC Experimental Loads D D M (2) 2.5 MW Dynamometers Test Machine and Controls 5000 hp Motor Test Cell Power Systems Conference 2002 Impact of Distributed Generation

24. Summary and Conclusion • Only an integrated power system makes economic sense for warships • Large-scale use of power electronic devices in close-coupled systems cause harmonic problems at levels rarely encountered in utility or industrial environments • All-electric ships need novel concepts for its integrated power system • Building of knowledge base for modeling and simulation is needed • Real-time simulation with power system components as hardware-in-the-loop will offer unique opportunity to study harmonic issues Power Systems Conference 2002 Impact of Distributed Generation