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Grand Challenges in Electric Power Engineering: Extreme System Reliability

Grand Challenges in Electric Power Engineering: Extreme System Reliability. G. T. Heydt Arizona State University Tempe, Arizona Summer Meeting 2002. Electric power quality Extreme bus voltage reliability, for example 'five nines' (i.e., 0.99999 availability), or six nines or even higher

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Grand Challenges in Electric Power Engineering: Extreme System Reliability

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  1. Grand Challenges in Electric Power Engineering:Extreme System Reliability G. T. HeydtArizona State UniversityTempe, Arizona Summer Meeting 2002

  2. Electric power quality • Extreme bus voltage reliability, for example 'five nines' (i.e., 0.99999 availability), or six nines or even higher • Utilization of new transmission and distribution technologies for improvement of reliability • Utilization of distributed energy sources (DERs) to improve reliability • Working with manufacturers of information technology equipment to reduce load vulnerability

  3. Distributed rather than concentrated loads • Loop circuits for distribution systems • Information Technology and sensitive manufacturing loads • Independence of energy sources • Environmental issues

  4. 7/24 UTILIZATION OF POWER SYSTEM ULTRA HIGH RELIABILITY INFORMATION PROCESSING, FINANCIAL SERVICES, AIRLINES, POLICE, MILITARY

  5. AS A RESPONSE TO THE 1993 TERRORIST BOMBING OF THE WTC, THE PRIMARY DISTRIBUTION SYSTEM IN THE BUILDING WAS IMPROVED TO KEEP THE POWER ON IN THE CASE OF SEVERE DISRUPTION OF THE SUPPLY / INTERRUPTION OF THE IN-BUILDING PRIMARY DISTRIBUTION. THERE WERE TEN SUBSTATIONS IN EACH WTC TOWER, ON FLOORS 7, 41, 75, AND 108, AND THE SOUTH TOWER HAD AN ADDITIONAL TENANT OWNED DOUBLY FED SUBSTATION ON FLOOR 43

  6. THE USE OF MULTIPLE FEEDS, MULTIPLE SUBSTATIONS, AND ISOLATED POWER SUPPLIES KEPT THE POWER ON IN MOST OF THE WTC FOR 102 MINUTES AFTER THE INITIAL STRIKE. IT IS BELIEVED THAT THIS WAS THE MAIN FACTOR IN SAVING THE LIVES OF AS MANY AS 18,000 PEOPLE WHO ESCAPED FROM THE TOWERS BEFORE COLLAPSE

  7. INDEPENDENCE OF SOURCES LOAD 1-P = (1-P1)(1-P2) TWO FEEDERS RELIABLE LOAD BUS The dependence of the sources will result in a much higher outage rate than (1-P1)(1-P2)

  8. The dependence effect of multiple sources can be modeled using a difference equation of the form qn+1 = Cqn+(1-C)(q1)1/n qn whereqn = 1-pn = outage rate of circuit upon addition of nth feeder, C is a correlation coefficient The(q1)1/nterm is called a discounting term and it accounts for increased potential for dependence for cases of large n (large numbers of feeders)

  9. DISCOUNTED MODEL C = 0 indicates no correlation between multiple feeders C = 1 indicates the feeder outages among several feeders are ‘common mode’

  10. The addition of feeders to improve reliability has a diminishing effect. For practical cases, use of more than three ‘independent’ feeders of 100% capacity is counter- productive.

  11. 300 20 110 30 200 100 EXPECTED CAPACITIES SHOWN

  12. PROBABILITIES OF UNCOMMON EVENTS COMMON (?) Event . Loosing at roulette 00 in Las Vegas Loosing the PowerBall lottery FAA design criteria for aircraft LIFE Probability N 97.3684 1.6 99.99995 6.3 0.999999999 0.999999999999 9 to 12 POWER SYSTEM RELIABILITY Reliability N Outage time 99.9 3 8h 45 min / yr 99.998631 4.9 1 day / 200 yrs 99.999 5 5 min 15 s / yr 99.99999 7 3.2 s / yr 99.999999 8 18.9 cycles / yr 99.9999999 9 1.8 cycles / yr

  13. DISTRIBUTED GENERATION FUEL CELLS MICROTURBINES DIESEL SETS MOTIVATION RELIABILITY ENHANCEMENT ENVIRONMENTAL ISSUES COGEN APPLICATIONS TRANSMISSION CONGESTION

  14. Many alternative generation sources have power electronic interfaces with the 60 Hz load bus. In some designs, the DC bus may be integrated with a battery energy storage system for seamless transfer of the load.

  15. FUEL CELLS HYDROGEN ANODE CATALYST DC LOAD ELECTROLYTE CATALYST i(t) WATER AND HEAT CATHODE OXYGEN

  16. POTENTIAL HIGH EFFICIENCY SPECIAL APPLICATIONS FOR COGEN MOBILE (AUTO) AND SPACE APPLICATIONS A LOT OF PROPONENTS RELIEVES TRANSMISSION CONGESTION TRULY INDEPENDENT ENERGY SOURCE VERY HIGH COST POTENTIAL RELIABILITY PROBLEMS NOT GENERALLY COMMERCIALLY AVAILABLE USES EXOTIC MATERIALS / CATALYSTS HIGH TEMPERATURE / SAFETY ISSUES GENERALLY NOT SUITED AT HIGH POWER LEVELS AND HIGH RELIABILITY APPLICATIONS FEW REALISTIC APPLICATIONS REQUIRES DC / AC CONVERSION DIFFICULT TO CONTROL WHERE IS ALL THIS FUEL GOING TO COME FROM? NO ECONOMY OF SCALE ENVIRONMENTAL ISSUES NOT WELL THOUGHT OUT NEEDS MORE RESEARCH / BREAKTHROUGHS LARGE SIZE FUEL CELLS

  17. POTENTIAL HIGH EFFICIENCY SPECIAL APPLICATIONS FOR COGEN MOBILE (AUTO) AND SPACE APPLICATIONS A LOT OF PROPONENTS RELIEVES TRANSMISSION CONGESTION TRULY INDEPENDENT ENERGY SOURCE VERY HIGH COST POTENTIAL RELIABILITY PROBLEMS NOT GENERALLY COMMERCIALLY AVAILABLE USES EXOTIC MATERIALS / CATALYSTS HIGH TEMPERATURE / SAFETY ISSUES GENERALLY NOT SUITED AT HIGH POWER LEVELS AND HIGH RELIABILITY APPLICATIONS FEW REALISTIC APPLICATIONS REQUIRES DC / AC CONVERSION DIFFICULT TO CONTROL WHERE IS ALL THIS FUEL GOING TO COME FROM? NO ECONOMY OF SCALE ENVIRONMENTAL ISSUES NOT WELL THOUGHT OUT NEEDS MORE RESEARCH / BREAKTHROUGHS LARGE SIZE FUEL CELLS

  18. PHOSPHORIC ACID 250 kVA FUEL CELL PROTON EXCHANGE MEMBRANE FUEL CELL - 7.5 kVA

  19. MICROTURBINES • Low capacity, high speed units with electronic interface with 60 Hz bus • Alternative fuel sources (e.g., biogas, gasifier, pyrolysis, fuels that have less than 10% of heat content compared to fossil fuels) • Catalytic combustor to reduce nitrous oxide production • Heat recovery • Lower capacities -- e.g., 5 - 300 kVA • High efficiency small units

  20. MICROTURBINES Proposed application areas • Electric vehicles • Capacity addition • Stand alone power supplies • Cogeneration / resource recovery • Peak shaving • High reliability applications, independent fuel source

  21. The main grand challenges of achieving N nines reliability using DERs are: • Development of strategies for adding DERs • Development of analytical procedures for systems of multiple local controls, and the coordination of those controls • The complete analysis of normal and abnormal operating modes of DERs • The resolution of safety issues relating to energization of distribution buses at the load end • The rethinking of protective relaying issues for systems with multiple DERs • The advancement of agent technologies for systems reliability enhancement, and the resolution of issues of power electronic controller compatibility • Analysis of dependence of fuel sources

  22. ELECTRONIC SOLUTIONS FOR POWER CONDITIONING Related to high reliability requirements because momentary events can degrade overall customer load performance. Electronic solutions, while expensive, can drastically reduce the number of momentary events; however the electronic devices have reliability concerns of their own.

  23. Inject series voltage for phase control / exchange energy between phases ELECTRONIC SOLUTIONS FOR POWER CONDITIONING Shunt positioning in system to inject current Back - to - back rectifier / DC link / inverter

  24. AC - AC CONVERTER TECHNOLOGIES RECTIFIER DC link PWM INVERTER THE UNIFIED POWER FLOW CONTROLLER UTILIZES IGBT TECHNOLOGY TO GENERATE PWM SIGNALS OF CONTROLLABLE MAGNITUDE / PHASE. THIS EFFECTIVELY CONTROLS THE ACTIVE POWER FLOW WHEN INJECTED AS A SERIES VOLTAGE

  25. 1/4 cycle response time Very low DC link power Can be protected by crowbaring supply Individual phase control / exchange energy between phases Controls slow variations in supply voltage The distribution version (DVR) can improve supply power factor and power quality For the distribution version, potential elimination of vulnerable load problems For UPFC, can reduce transmission congestion as well as improve dynamic response Cost is high Local solution (?) Controls are tricky, coordination of controls Solution of diversity of ownership problems Relatively low power injected Limited experience in applications Reliability issues THE UPFC

  26. ALLOWS CONTROL OF POWER FLOW CONDITIONS POWER CONTROLS CAN BE COORDINATED TO ENHANCE DYNAMIC STABILITY CAN SELL TRANSMISSION CAPACITY REACTIVE POWER SUPPORT CAN REPLACE SPECIAL PROTECTION SCHEMES WITHOUT THE NEED OF GENERATOR RESYNCHRONIZATION COST LITTLE EXPERIENCE IN ACTUAL USE RELIABILITY ISSUES PQ IMPLICATIONS THE UPFC FACTS DEVICEas a transmission element

  27. THE UPFC and DVR POWER FLOW SERIES XFORMER SUPPLY LOAD AC/AC PWM CONVERTER

  28. THE UPFC and DVR LOAD VOLTAGE SERIES VOLTAGE SUPPLY VOLTAGE LOAD CURRENT

  29. SUMMARY THE GRAND CHALLENGES

  30. Modeling and controlling energy source dependence • Resolving reliability and control issues for DERs • Evolution of power electronic topologies for high reliability applications • Control of the cost / benefit ratio for alternative high reliability designs • Agent design for DERs and agent communications issues • Study of typical global system response due to local controls • ‘Adding another 9’

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