Designing All Electric Ships

Transcription

1 CAPT Norbert Doerry Howard Fireman Naval Sea Systems Command Ann Arbor, Michigan May 16-19,

2 AGENDA Integrated Power System (IPS) Introduction IPS Design Opportunities IPS Design Considerations IPS Design Watch Items Conclusions The Integrated Power System provides the naval architect with many opportunities to optimize ship design. It s important that the Naval Architect take advantage of these opportunities, otherwise a sub-optimized IPS ship design may not outperform an optimized conventional mechanical drive ship design. Improving the efficiency of prime movers and propulsors (along with drag reduction) can compensate for lower transmission efficiency of electric drive. 2

3 Integrated Power System (IPS) IPS consists of an architecture and a set of modules which together provide the basis for designing, procuring, and supporting marine power systems applicable over a broad range of ship types: Power Generation Module (PGM) Propulsion Motor Module (PMM) Power Distribution Module (PDM) Power Conversion Module (PCM) Power Control (PCON) Energy Storage Module (ESM) Load (PLM) 3

4 Integrated t Power IPS Architecture Propulsion and Ship Service Loads provided power from same prime movers Zonal Distribution Longitudinal Distribution buses connect prime movers to loads via zonal distribution nodes (switchboards or load centers). 4

5 IPS: Medium Voltage AC Design PDM - PCM Xformer 4160 V PDM - PCM Xformer 4160 V PDM - PCM Xformer 4160 V PDM - PCM Xformer 4160 V SP PGM PGM PGM PDM PDM PDM PMM PMM PDM SP SP PDM PDM PGM PGM PGM Xformer 4160 V PDM - PCM Xformer 4160 V PDM - PCM Xformer 4160 V PDM - PCM Xformer 4160 V PDM - PCM Zone 1 Zone 2 Zone 3 Zone 4 Zone 5 Zone 6 Zone 7 SP = Shore Power 5

6 IPS with Zonal Electrical Distribution: Medium Voltage AC Distribution System PGM To ZEDS To ZEDS PGM PMM Motor Drive Motor Motor Drive Motor PMM PGM To ZEDS PGM 6

7 Zonal Electrical l Distribution ib ti System AN ELECTRICAL ZONE AN ELECTRICAL ZONE AN ELECTRICAL ZONE AN ELECTRICAL ZONE PCM-1 PCM-1 PCM-1 PCM-1 AC INPUT PCM-4 AC LOADS PCM- 2 PCM-2 AC LOADS PCM- 4 AC INPUT PCM- 2 AC LOADS LOADS AC LOADS PCM- 2 PCM-4 AC INPUT PCM-1 PCM-1 PCM-1 PCM-1 7

8 IPS Design Opportunities Support High Power Mission i Systems Reduce Number of Prime Movers Improve System Efficiency Provide General Arrangements Flexibility Improve Ship Producibility Support Zonal Survivability Facilitate Fuel Cell Integration 8

9 Support High Power Mission i Systems High Powered Sensor Combination Sensor and Weapon High Powered Microwave High Powered Laser Organic Surveillance Drone High Altitude Beam Power to Aircraft Minimal Handling - No Refueling Electromagnetic Gun More than 10 MJ on Target Megawatt Range Integrated Power System Affordable Power for Weapons and Propulsion Power Dense, Fuel Efficient Propulsion Reduced Signatures Power Conversion Flexibility All Electric Auxiliaries No Hydraulics No HP Gas Systems Reduced Sailor Workload High Energy Laser Enhanced Self Defense Precision Engagement No Collateral Damage Megawatt Class Laser NO ENERGETICS ABOARD SHIP! 9

10 Reduce Number of Prime Movers Ship s Power Propulsion Traditional Electric Drive with Integrated Power Pi Prime Mover Prime Mover Prime Mover Prime Mover Prime Mover Prime Mover Prime Mover GEN GEN GEN GEN GEN GEN GEN Power Conversion and Distribution ib ti Power Conversion and Distribution Prime Mover Prime Mover Prime Mover Prime Mover MD MD Reduction Gear Reduction Gear Mtr Mtr 10

11 Improve System Efficiency A generator, motor drive and motor will generally be less efficient than a reduction gear. But electric drive enables the prime mover and propulsor to be more efficient, as well as reducing drag. Mechanical Drive Electric Drive Gas Turbine 30% 35% Reduction Gear 99% Generator 96% Drive 95% Motor 98% Propeller 70% 75% Relative Drag Coefficient 100% 97% Total 21% 24% Ratio 116% Representative values: not universally true TRADE TRANSMISSION EFFICIENCY TO REDUCE DRAG AND IMPROVE PRIME MOVER AND PROPELLER EFFICIENCY 11

12 Increased Efficiency Recover Swirl Flow 10 15% improvement Improve System Efficiency: Contra-Rotating Propellers Requires special bearings for inner shaft if using common shaft line Recent examples feature Pod for aft propeller Anders Backlund and Jukka Kuuskoski, The Contra Rotating Propeller (CRP) Concept with a Podded Drive 12

13 General Arrangements Flexibility Improve Ship Producibility Vertical Stacking of Propulsion Components Di lm h i ls t Pods Athwart ship Engine Mounting Horizontal Engine Propulsion / Electrical Power Foundation Machinery Space Intakes/Uptakes Engines in Z ones With out Pr opu lsi on / Electrical Power Spaces Superstructure Shaft Lin e Distributed Propulsion Small Engineering Spaces Diesel Mechanical System Integrated Power System 12 APR94 G.CDR NH D: S EA 03R 2 Rev 1 28 MAR 95 13

14 Support Zonal Survivability Zonal Survivability is the ability of a distributed system, when experiencing internal faults, to ensure loads in undamaged zones do not experience a service interruption. Sometimes applied to only Vital Loads. Usually requires es one longitudinal bus to survive damage. Limits damage propagation to the fewest number of zones. Enables concentration of Damage Control / Recoverability Efforts. 14

15 Facilitate Fuel Cell Integration Many Advantages Highly Efficient (35-60%) No Dedicated intakesuptakes; use ventilation Challenges Reforming Fuel into Hydrogen Onboard Chemical Plant. Eliminating Sulfur from fuels. Slow Dynamic Response Requires Energy storage to balance generation and load Slow Startup Best used for base-loads 15

16 IPS Design Considerations Selection of High Voltage Bus Voltage Number and Type of Power Generation Modules Propulsion Motor Module Technology Propulsor Architecture AC or Zonal Electrical Distribution 16

17 Selection of High Voltage Bus Voltage Higher Voltages Desired Circuit Breaker Rating Reduced Cable Weight 40 Generator Reactance Lower Voltage Desired Reduce risk for corona 7 80 Possible elimination of 0 14 transformer for propulsion motor module Insulation and Thermal design of Generator Shore Power 450 V, 4.16 kv or 13.8 kv desired Total Generation Power Required (MW) 450 VAC 416kV kV 6.9kV 13.8kV Selecting the bus voltage is a compromise 17

18 Number and Type of Power Generation Modules Past studies have shown that 4 to 6 power generation modules generally provide the most cost effective solutions. Typically have at least 2 larger Main generators and 2 smaller auxiliary generators Auxiliary Generators sized to be efficient between the minimum operating conditions (with 2 online) and the point where the main generators are efficient. Often Diesel Generators Should be self-starting Main Generators sized to provide maximum power requirements along with auxiliary generator sets Often Gas Turbine Generators An even number simplifies bus architecture May also need small emergency generators for dark-ship start 18

19 NINTH INTERNATIONAL MARINE DESIGN CONFERENCE 2006 Propulsion Motors: General Observations Propulsion Motors are typically custom designed for the application based on standard Frame Sizes. Frame size determines rotor diameter. Variables are length and shaft speed. The Motor Drive has a large impact on both the Propulsion Motor and the High Voltage Distribution ib ti System. Harmonics and Power Quality Part Load Efficiency Number of Motor Phases Need for Propulsion Transformer Motor Designs have changed significantly in past 15 years to take advantage of new high voltage and current power electronics. Permanent Magnet (PM) and Advanced Induction Motors (AIM) have largely displaced and Synchronous Motors for high power applications. Homopolar Motors and Superconducting Motors are still being developed. 19

20 Motors: Basic Scaling Law HP D 2 L A B RPM HP Power Rating D Rotor Diameter L Rotor Active Length A Surface Current Density (Conductor Material & Cooling Method) B Rotor Flux Density (Saturation of Magnetic Material) RPM Shaft Speed 20

21 Propulsion Motor Thumb Rules For a given technology, cost is roughly proportional to Torque. Maximum Rotor Diameter is limited by shaft rake considerations, manufacturability, and transportability. Motor efficiencies at design power typically fall in range of f9098% 90-98%. Below about 15-35% rated power, the efficiency of a conventional motor drops rapidly. Can be improved through advanced motor design and proper integration with motor drive Representative Efficiency Curves 21

22 Propulsor Architecture Improve Efficiency Fixed Pitch vs. CPP Contra-rotating Pods Tandem Motors Maneuverability Trainable Pods Thrusters Survivability Distributed Propulsion Support innovative Hull Design SWATH Multi-Hulls 22

23 AC or Zonal Electrical Distribution AC Zonal Electrical l Distribution ib ti is preferred when Power Quality of the high voltage bus is good enough such that ship service loads receive power meeting MIL-STD section 300A Interface standards. Depends on Motor Drive Technology Depends on Harmonic Filtering on high voltage bus The number of un-interruptible loads is small. Otherwise, Zonal Electrical Distribution (or Integrated Fight Through Power IFTP) is generally preferred 23

24 IPS Design Watch Items Part Load Efficienciesi i Dark-Ship Starts Shore Power Power Generation Module Start Time Component Reliability Common Mode Failure Transformer In-Rush Current 24

25 Conclusions The Integrated t Power System provides the naval architect with many opportunities to optimize ship design. It s important that the Naval Architect take advantage of these opportunities, otherwise a sub-optimized IPS ship design may not outperform an optimized conventional mechanical drive ship design. Improving the efficiency of prime movers and propulsors (along with drag reduction) can compensate for lower transmission efficiency of electric drive. 25