Standards in Marine Power Systems APEC 2014 Session IS2.1 Power Electronic Standards Roger Dougal University of South Carolina Columbia, SC 29208
Need is Driven by Electrification Oasis of the Seas DDG 1000 Electric CNG T-AGOS 23 Type 45 Transition from mechanical to electric drive is underway Many of same reasons as for autos: Higher efficiency Reduced operating/maintenance costs Larger electric loads share propulsion power sources Power demands can be immense 100 MW Cannot be achieved with more of the same Requires transformational new technologies Pushing the transformation quickly requires the safety of standards
History of Ship-related Power Electronics Standards Activities P 1662 Guide for Design and Application of Power Electronics in Electrical Power Systems on Ships P1676 Guide for Control Architecture for High Power Electronics (1 MW and Greater) used in Electric Power Transmission and Distribution Systems P1709 Recommended Practice for 1-35 kv Medium Voltage DC Power Systems for Ships P1821 Design tools for PEBB-based Systems P1826 Draft Standard for Power Electronics Open Systems Interfaces in Zonal Electrical Distribution Systems Rated above 100kW
1662 Guide for Design and Application of Power Electronics in Electrical Power Systems on Ships Issued 2008 Sponsor IAS Petroleum and Chemical Industry Committee Motivation Recommend a methodology for analysis and specification of power electronics equipment for use in marine power systems.
1662 Outlook Although not explicitly ac, presents appearance of fairly conventional power system that contains power electronic components Covered equipment: Inverters, rectifiers, converters, power factor correctors, active filters, solid state circuit breakers, current limiters, motor drives, electric propulsion, uninterruptable power supplies, energy storage Application examples show multiple generators connected to main power buses, redundantly-fed propulsion motors (variable speed drives), ac transformers, notations for solid state transformers, perhaps ring bus arrangements Defines concepts of zonal power distribution, integrated power/propulsion systems
1662 Topics Addressed System voltages Power rating Duty cycle Efficiency No-load losses Overload Stress limits and derating factors Power quality requirements Grounding Protection requirements Protection for regenerated power Inrush current protection Overvoltage protection Protection against moisture and condensation Surge voltage withstanding capability Dynamic requirements Size and weight Reliability requirements Maintainability requirements Selection of parts Isolating means Fuses Solid state power switches Heat dissipation Environmental conditions and cooling Airborne noise Structure-borne noise Vibration Electromagnetic interference (EMI) Data communication Control circuits Software Enclosures Clearance and creepage Power cables terminations Network and control cable terminations Quality assurance requirements
1676 Guide for Control Architecture for High Power Electronics (1 MW and Greater) used in Electric Power Transmission and Distribution Systems Sponsor PES, Substations Committee (but many of the same participants as 1662) Motivation Promote adoption of standard control architectures, control partitions, permitting separation between power and control functions, permitting multiple vendors to participate as equipment suppliers 2010
Defines principles of control partitions Temporal Functional Recommends control architecture based on layered functions, and interfaces between layers Describes some application examples 1676 Main Points
Control Layers System control layer System mission, human interface, all above the level covered by this guide Application control layer Commands lower layers that are considered to be essentially controlled voltage or current sources Converter control layer Waveform-level feedback control, V and I sensing, synchronism with e.g. ac waveforms, Switching control layer Switch modulation, protection logic Hardware control layer Gate level controls of power devices Faster More device specific
1709 Recommended Practice for 1-35 kv Medium Voltage DC Power Systems for Ships 100 MW 225 kt 360 m Size matters 80 MW 14 kt 180 m Sponsor IAS Petroleum and Chemical Industry Committee Motivation Provide basis for (hopefully) introducing more power dense dc power systems Release date 2010
MVDC Advantages Simplify connection and disconnection of diverse power generation and storage devices Reduce size and ratings of switchgear Eliminate large line-frequency transformers Limit and manage fault currents, then reconfigure Eliminate reactive voltage drops Enable bi-directional power flow Reduce power system weight by using high speed generators Enable higher power ratings for given cable size Improve control of power flow, especially in transient and emergency conditions Reduce fuel consumption - allow variable engine speed Use energy storage to improve energy efficiency Eliminate need for phase angle synchronization of sources
1709 Main Points Defines voltage classes, envisioning bipolar bus (± 1.5, 3, 6, 9, 12, 15 kv), and max voltages in each class (± 2.5, 5, 8, 11, 14, 17) Proposes withstand voltages for non-electronic components (cables, fuses, switchgear, etc) (e.g. 27kV for 6kV class) Over-current withstand duration much shorter than for traditional switchgear (e.g. 1 ms vs 0.5 s) Grounding dc ground current mitigation, galvanic isolation Stability transient recovery, bounded transients, no limit cycle behavior Efficiency spec at various loadings Quality of service classes of loads uninterruptible, short-term interrupt, longterm interrupt, exempt loads Power quality regulation, ripple Inrush and outrush current limitations to all equipment Load current rise rate limits related to bus supply rate limits Discharge procedures for storage elements Recommended studies to ensure safe and effective system operation Load flow, transient response, short circuit currents, etc.
1821 Design Tools for PEBB-based Sponsor Systems PES Working group i8 PEBB systems Motivation Describe the sets of software design tools that permit rapid application of building-block power technologies. Simplify and speed the introduction of scalable and robust power electronics equipment based on standard building blocks Work in progress
1826 Draft Standard for Power Electronics Open Systems Interfaces in Zonal Electrical Distribution Systems Rated above 100kW Sponsor IAS Petroleum and Chemical Industry Committee PELS Standards Committee Motivation Extend the work of 1676 to promote open system concepts for ship power systems Define how open system interfaces should be verified and validated Work in progress
Principles
Zonal System and Controls
1826 Main Points Defines concept of zonal electric power systems (relevant to microgrids) Defines components that make up zonal system, including converter from external to in-zone distribution bus, bus-toin-zone conversions, in-zone energy storage Identifies general equipment requirements Power interfaces, control power, inrush current, isolation devices Operating modes (e.g. energy storage - charge, float, discharge, support bus) Monitoring, information exchange, control, protection interfaces Multi-zone control, zonal control, in-zone control
Specifies voltage tolerances From 1709. These were loosely based on traditional ac system principles. May be unnecessarily restrictive for power electronic systems.
Verification and Validation Extensive treatment of V & V Concept verification Requirements verification Design verification First article verification and validation Integration testing Qualification testing Commissioning testing Acceptance testing
Summary Marine power systems are trending large and are driving adoption of fully-electronic power control methods and dc power distribution at the 100 MW level. Standards and recommended practices have been/are being developed to facilitate more widespread applications Commercial and defense applications abound