WECC Board of Directors Meeting - PowerPoint PPT Presentation

1 / 46
About This Presentation
Title:

WECC Board of Directors Meeting

Description:

Special care taken to design and protect grid interface ... All practices and mechanisms for maintaining system reliability must not be infringed ... – PowerPoint PPT presentation

Number of Views:68
Avg rating:3.0/5.0
Slides: 47
Provided by: christophe249
Category:

less

Transcript and Presenter's Notes

Title: WECC Board of Directors Meeting


1
Wind Generation Interconnection and Integration
Status and Challenges
  • WECC Board of Directors Meeting
  • November 30, 2005Tucson, Arizona

Robert M. ZavadilVice-President Principal
Consultant144-E Market Place BoulevardKnoxville,
Tennessee 37922Tel (865) 691-5540 ext.
149bobz_at_enernex.comwww.enernex.com
2
Wind Plant Interconnection History
  • Early (1980s into 1990s)
  • Wind generation viewed as curiosity
  • Special care taken to design and protect grid
    interface
  • Preferred action for turbines during grid
    disturbance was to disconnect
  • California thing
  • Mid 1990s
  • Development of large wind generation facilities
    outside of California
  • Increasing plant sizes crossed threshold for
    interconnection evaluations
  • Control area penetration still negligible, so
    studies were many times more of a formality
  • 2000 to present
  • Continued growth of wind generation led to
    questions that could no longer be prudently
    neglected
  • West Texas voltage and transmission capacity
    questions
  • Growing awareness of wind plant sensitivity to
    grid disturbances, and possible consequences
    (with further growth)
  • Recognition of the unique characteristics of
    wind, and the potential for increased operating
    costs as penetration grows (integration
    questions)
  • Continued favorable environment for further
    development of wind generation

3
Interconnection vs. Integration
  • Convenient categories for all issues and
    challenges related to wind generation
  • Interconnection
  • Questions are primarily technical, centered on
    transmission network
  • Thermal, voltage, transfer limits
  • System stability and security
  • Focus in on events, contingencies, abnormal
    conditions
  • Integration
  • Larger emphasis on economics
  • Involves interaction of all generators with all
    loads
  • Transmission capacity also plays a role
  • Focus on normal operating conditions

4
Relationship to System Reliability
  • Reliability is the driver for power system
    engineering and operations practice
  • The transmission network is a major factor in
    power system reliability
  • Interconnection
  • New network elements must not jeopardize the
    operation of any other network equipment
  • The ability of the system to withstand a major
    disruption must not be diminished by the
    connection of a new element
  • Integration
  • Wind generation will likely result in
    re-deployments of other network elements
  • All practices and mechanisms for maintaining
    system reliability must not be infringed

5
Status Wind Generation Interconnection in
North America
  • Activities underway simultaneously at many levels
  • Achieving convergence is a necessity
  • Most individual interconnection procedures must
    comply with FERC 2003a
  • Will also adhere to NERC view, as yet not fully
    determined
  • Technical capabilities are increasing
  • Growing database of wind turbine models for
    analysis platforms
  • Increasing industry experience with power system
    studies involving wind generation facilities
  • Consensus on technical performance requirements
  • Much progress has been made over past five years,
    but next few years should be interesting
    nonetheless

6
The Present - Interconnection
  • A number of efforts to sort out Interconnection
    issues for wind generation are underway in the
    North America
  • FERC Order 2003a
  • AWEA best practices
  • NERC wind generation task force
  • WECC reliability standards for wind generation,
    model development
  • Alberta Electric System Operator (AESO)
    interconnection guidelines
  • Western Area Power Administration transmission
    issues related to wind development in the Dakotas
  • New York ISO Impact of Wind Generation on
    Reliability of NYSBPS
  • Growing awareness of wind generation within the
    IEEE Power Engineering Society (IEEE PES)
  • Wind Generation TF
  • Seminars and special sessions
  • Interest from other technical committees
    formative stages
  • UWIG

7
Wind Generation Technology
  • Wind turbine electrical technology
  • Conventional induction machines
  • Induction machines w/ static power converter
    control
  • A few utilize more exotic technology (e.g.,
    direct drive)
  • Important considerations for integration studies
  • Steady-state characteristics P, Q, PF
  • Dynamic response to grid disturbances
  • Intermittency variation of P Q with time
  • Output quality
  • Wind plant Technology
  • Behavior of aggregate plant can depend greatly on
    this element
  • Advanced capabilities with advanced SCADA
  • Distributed static VAr generation
  • Ramp rate control

8
Interconnection Challenges
  • Remote facilities
  • Typically interconnection to weak transmission
    network
  • Transmission capacity questions
  • Reactive power dispatch
  • Dynamic character of wind generation
  • Reactive power planning for network must be
    coordinated with wind plants
  • Interconnection requirements are evolving
  • Were typically very simple
  • Evolving to voltage control, dynamic reactive
    power management

9
Windplant Modeling Challenges
  • How to model large number of relatively small
    generators?
  • Unfamiliar generator technologies (relative to
    conventional synchronous machines and generating
    plants)
  • Sometimes extensive medium voltage system plant
    Q is very dependent on MV system (I2X)
  • Auxiliary equipment and systems
  • Switched capacitors on collector system
  • Switched capacitors at interconnect substation
  • Plant-level systems
  • GE DVAR
  • Variable and uncertain fuel supply

10
Emergence of Grid Codes
  • Burst onto the scene about four years ago
  • Driven in U.S. by two major technical issues
    (primarily)
  • Turbine sensitivity to grid voltage disturbances
    (low-voltage ride-through)
  • Reactive power management / voltage control
  • Led to major challenges for industry
  • Turbine design
  • Plant design
  • Recognition of the wind industry uniqueness
  • Short project lead times
  • Modeling complexity

11
FERC Order 2003a, 661
  • Wind generation recognized as requiring some
    special considerations in Order 2003a
  • Input from collection of stakeholders organized
    by AWEA
  • Concerns captured as Appendix G to order
  • Appendix G
  • Developed by AWEA-led stakeholder group
  • Low-voltage ride-through (right)
  • Basic reactive power requirements
  • Need for SCADA
  • Issued by FERC as Order 661
  • NERC objects to parts of 661, files request for
    rehearing
  • FERC directs AWEA and NERC to resolve

Wind plant LVRT specification from Appendix G of
FERC Order 2003a
12
NERC/AWEA Resolution on LVRT
  • All wind generating plants subject to FERC Order
    No. 661 and not covered by the transition period
    must meet the following requirements
  • Wind generating plants are required to remain
    in-service during three phase faults with normal
    clearing (which is a time period of approximately
    4 9 cycles) and single line to ground faults
    with delayed clearing, and subsequent post-fault
    voltage recovery to pre-fault voltage unless
    clearing the fault effectively disconnects the
    generator form the system.
  • The clearing time requirement for a three-phase
    fault will be specific to the wind generating
    plant substation location, as determined by and
    documented by the transmission provider.
  • The maximum clearing time the wind generating
    plant shall be required to withstand for a
    three-phase fault shall be 9 cycles
  • after which, if the fault remains the wind
    generating plant may disconnect from the
    transmission system.
  • The wind generating plant shall remain
    interconnected during such a fault on the
    transmission system for a voltage level as low a
    zero volts, as measured at the high voltage side
    of the wind GSU.

13
New LVRT Requirement per FERC (cont)
  • This requirement does not apply to faults that
    would occur between the wind generator terminals
    and the high side of the GSU.
  • Wind generating plants may trip after the fault
    period if this action is intended as part of a
    special protection scheme.
  • Wind generating plants may meet the LVRT
    requirements of this standard by (utilizing) the
    performance of the generators or by installing
    additional equipment (e.g., Static VAr
    Compensators, etc.) within the wind generating
    plant or by a combination of generator
    performance and additional equipment.
  • Existing individual generating units that are, or
    have been, interconnected to the network at the
    same location at the effected date of the
    Appendix G LVRT Standard are exempt from meeting
    the Appendix G LVRT Standard for the remaining
    life of the existing generation equipment.
    Existing individual generator units that are
    replaced are required to meet the Appendix G LVRT
    Standard.

14
Wind Generation Technology Trends
  • Wind Turbines
  • Continuing movement to variable speed
  • Emergence of full-converter topologies
  • Enhanced grid compatibility (driven by grid
    codes)
  • Continued emphasis on production, availability
    (low wind speed)
  • Wind Plants
  • Increasing emphasis on interconnection behavior
    of entire plant, not just turbine
  • Higher performance driven by grid codes (e.g.
    LVRT, voltage control requirements
  • Other
  • Research and development on advanced features
    (e.g. intertial and governor response)

15
NERC Wind Generation Task Force
  • In wake of Order 2003a, established task force to
    assess power system planning and reliability
    issues related to wind generation
  • Task Force convened January, 2005 with cross
    section of stakeholder technical representatives
  • Transmission owners/operators
  • Regional Transmission Organizations
  • Generating companies
  • Wind Industry (AWEA UWIG)
  • Objectives
  • Identify any and all issues related to wind
    generation that have implications for power
    system reliability
  • Determine if issue can be addressed through
    standards
  • Develop SARs (standards authorization requests)
    for areas where new standards may be necessary
  • TF assignment complicated by ongoing,
    comprehensive revision of NERC standards
  • Task Force Period of Performance CY2005

16
WECC Wind Turbine Modeling Initiative - Drivers
  • Wind generation is no longer invisible
  • WECC has 3.7 GW of wind generation capacity
    installed
  • Some areas are experiencing high saturation
    levels
  • Significant expansion expected in the near future
  • Adequate simulation models are indispensable
  • Identify and address impact of new generator
    additions
  • Perform planning studies to maintain system
    reliability at the local and regional level
  • The Status Quo is not acceptable to WECC
  • One-of-a-kind and proprietary models are
    incompatible with the current system modeling
    practice in WECC
  • Difficult and confusing for users
  • Cannot be maintained in base cases once plant is
    built

17
Proposed standard models
  • Based on characteristics of grid interface
  • Type A conventional induction generator
  • Type B wound rotor induction generator with
    variable rotor resistance
  • Type C doubly-fed induction generator
  • Type D full converter interface

Type A
Type B
Type C
Type D
18
Technical challenges
  • Wind generator modeling versus wind plant
    modeling
  • Wind plant equivalencing is required to reduce
    data and computational burden
  • WGMG will first concentrate on development of
    generic WTG dynamic models
  • Grid versus wind disturbances
  • Performance in response to grid disturbances can
    be modeled reasonably well using generic models
  • Performance in response to wind disturbances
    could introduce complications but note that
    this is less importance in the planning
    environment

19
Technical challenges
  • Single and multiple generator equivalencing

20
Wind Generation Interconnection -Other Ongoing
Activities
  • UWIG
  • IEEE PES
  • Power System Dynamics Committee Wind Gen. TF
  • Other technical committees in process of
    engaging
  • Wind Power Coordinating Committee established
    under Technical Council (June 2005)
  • International
  • Significant research ongoing
  • Coordination with US efforts
  • UWIG
  • WECC

21
Wind Integration Why the Concern?
  • Wind generation is an attractive source of
    electric energy
  • The electric power business is based on capacity
  • System planning
  • Reliability considerations
  • Wind energy doesnt fit this model well
  • Variability
  • Uncertainty
  • What are the financial consequences of these
    attributes?

22
What is Integration Cost?
  • Does buying wind energy increase costs to serve
    the remaining load?
  • Depends on the definition of buying
  • Consensus that the qualitative answer is Yes
  • Real question is How much?
  • General Definition
  • Increased cost of serving load not served by wind
  • Can be evaluated by comparing wind to equivalent
    energy source that imposes no incremental burden
    on operations
  • Elements
  • Conventional ancillary service regulation,
    reserves etc.
  • Increased costs due to variability of wind
    generation
  • Increased costs due to increased uncertainty in
    unit commitment and scheduling
  • Possibly some costs due to the actual value of
    energy delivered vs. the reference

23
Dealing with Variability and Uncertainty
  • We are accustomed to working with some degree of
    variability and uncertainty
  • Variability
  • Load varies by seconds, minutes, hours, by day
    type, and with weather
  • Supply resources may not be available or limited
    in capacity due to partial outages
  • Prices for power purchases or sales exhibit are
    not constant
  • Uncertainty
  • Operational plans are made on basis of best
    available forecasts of needs some error is
    inherent
  • Supply side resource available with some
    probability (usually high)

Key Questions
  • How does wind generation affect this existing
    variability and uncertainty?
  • What are the costs associated with the changes?
  • Can we maintain the integrity of the system under
    these new conditions?

24
Wind Generation Modeling Challenges
  • Most of the wind generation yet to be built
  • Expected geographic spread is substantial
  • Neglecting transmission issues, control area
    impacts are based on the behavior of the
    aggregate wind generation, not individual plants
  • Supply resources are managed as a group to meet
    load, maintain reliability and minimize cost
  • No one-to-X backups

A realistic representation of the wind generation
is critical to the study results
25
Approach Re-creating the Weather
  • Historical years (2000, 2002, 2003)
  • Increased temporal and spatial resolution (5 km2,
    10 min.)
  • Use historical data to initialize and guide
    numerical weather model
  • Save important weather variables at points of
    interest

26
Baseline Data for Study
  • Multiple years of 10-minute resolution data for
  • System load (scaled to study year)
  • Aggregate wind generation
  • Load data wind generation data from corresponding
    years
  • Allows a wide-rage of what if questions to be
    addressed through simulations and calculations

27
Low Correlation Period
28
High Correlation Period
29
Distribution of Hourly Changes(normalized)
Aggregate Production
Individual Plants
30
General Findings from Studies to Date
  • Good wind generation data is critical for
    assessing power system impacts
  • Chronological, historical
  • Relatively high resolution
  • Long-term
  • Represents geographic diversity
  • Correlated with actual load
  • Statistical and mathematical processing can help
    identify operating challenges

Ramp up requirement increased by wind
Ramp down requirement increased by wind
31
Variability and Uncertainty Examples
32
Insights and Perspectives
  • Geographic dispersion of wind plants
  • Substantially reduces effects of shorter-term
    wind plant output fluctuations
  • Major impacts seen at hourly level and with
    short-term planning (unit commitment and
    scheduling)
  • Wind generation forecasting can help to reduce
    these impacts
  • Markets
  • Access to liquid day-ahead and real-time markets
    can reduce integration costs
  • Provide additional low- to modest- priced
    resources for balancing and dealing with
    uncertainty of wind generation

33
Insights and Perspectives
  • Wind Generation Modeling
  • Meteorological simulations can provide
    high-quality data for assessing impacts
  • Labor and computationally intensive, but superior
    to alternative methods
  • Analytical Methods
  • Statistical and mathematical techniques can
    provide useful results more exhaustive
    validation would be helpful
  • Chronological simulations of power system
    operation are most straightforward (approach and
    results understandable by widest range of
    stakeholders) can be labor intensive and
    relatively costly, however

34
Status - Integration
  • Assessment of Integration questions also
    continues in the form of specific, focused
    studies, e.g.
  • Xcel Energy Minnesota (integration cost study)
  • Xcel Energy - Colorado (integration cost study)
  • State of Minnesota (Dept. of Commerce)/Xcel RDF
  • Sacramento Municipal Utility District
    (prospective integration study)
  • CAISO/CEC (integration study related to RPS)
  • BPA (shaping and firming services for wind
    generation)
  • Manitoba Hydro (integration study)
  • AESO (wind generation market impact assessment)
  • Analysis techniques are becoming more
    sophisticated and better accepted
  • High-fidelity chronological models of regional
    wind scenarios
  • Detailed consideration of specific operational
    practices or market rules
  • Application of power industry tools for analysis

35
Summary of Wind Integration Studies
Source UWIG
36
Ongoing Wind Integration Studies in WECC
  • EnerNex Studies
  • Sacramento Municipal Utility District
  • Public Service New Mexico
  • Idaho Power
  • Avista Corporation
  • Public Service Colorado
  • Others
  • California Intermittency Project (GE, for the CEC
    and CPUC)
  • Pacificorp (internal)
  • Puget Sound PL (internal)
  • Alberta Electric System Operator

37
Public Service New Mexico on the tails of
the curve
  • Operating challenges with wind generation
  • Existing 200 MW plant has measurable effect on
    control performance
  • More wind planned for control area
  • PNM control area
  • Small relative to existing wind
  • General shortage of regulating resources
  • Cannot purchase regulation service
  • Large, concentrated wind plant has significant
    impacts on CPS2

38
Wind Generation and ACE
Source A. Ellis Public Service New Mexico
39
High Resolution Simulations The Next Step
Areva TD eterra-simulatordispatcher training
environment
40
Question How are Wind Generation Forecasts used
in Power System Operations and Planning ?
  • Honest Answers
  • Poorly, at the moment, and
  • Were really not sure
  • Forecasting experience in US
  • Required by some more recent PPAs
  • Little attention paid to requirements for use
  • Motivation and incentives lacking
  • Therefore, view is that wind generation forecasts
    are of little value

41
Value Propositions for Forecasting
  • Economic
  • Characteristics of wind generation - variability
    and uncertainty are managed with minimum
    financial impact to remainder of supply portfolio
  • Positive attributes e.g. correlation with load
    or hydro inflows are leveraged
  • Security Reliability
  • Performance of energy transportation and delivery
    infrastructure is not compromised
  • Quality of electric service to customers is
    maintained

42
Nonetheless,
  • Wind generation forecasting seen as key to
    continued wind industry growth
  • Value of wind generation forecast being
    demonstrated in some integration studies
  • e.g. NYSERDA study by GE
  • 100 million annual forecast value
  • Work beginning on next phase
  • Testing of hypotheses
  • Concepts to implementation
  • Measuring performance and value, then fine tuning
  • Significant Activities in U.S.
  • XCEL Energy/MN RDF
  • Evolution of CA PIRP forecasting program
  • Various integration studies focused on use of
    short-term wind generation forecasts in RT
    operations

43
Status Wind Integration Costs from North
American Studies
  • A number of studies conducted over past five
    years
  • More in progress
  • Findings
  • Total integration costs for modest penetrations
    of wind generation (to 15 or 20) range from a
    couple to 5/MWH of delivered wind energy
  • Costs due to planning uncertainty and hourly
    variability seem to be most significant
  • Regulation costs are small
  • Much work remains
  • Forecasting impact/value
  • Sensitivity of integration costs to resource
    portfolio, operating practices
  • Market impacts
  • Enhanced algorithms for planning with higher
    uncertainty
  • Use of short-term forecast information in RT
    operations

44
Opportunities for Collaboration
  • Wind issues are entering the power engineering
    mainstream
  • Much to do
  • Talent and resource applied to problems is
    increasing steadily
  • IEEE PES is stepping up to the plate
  • Wind Plant Dynamics Working Group (2004)
  • Wind Power Coordinating Committee (2005)
  • Utility Wind Integration Group (UWIG)
  • Is currently the most active and relevant forum
    for exchange of wind energy-related power system
    information
  • Has taken on a more active role with formation of
    working groups (2004)
  • Groups work to identify and address most urgent
    questions regarding interconnection and
    integration of wind turbines and wind plants

45
UWIG Focus Areas and Topics
  • Operating Impacts Users Group
  • Methods for assessing operating impacts
  • Wind energy forecasting
  • High wind penetrations in a carbon-constrained
    world
  • Wind generation capacity valuation methods
  • Best practices for wind plant integration
  • Modeling and Interconnection Users Group
  • Wind turbine and plant models for dynamic
    simulations
  • Generic models for interconnection screening
    studies and base case models (WECC)
  • Short-circuit behavior of wind plants

46
IEEE Power Energy , November 2005
Write a Comment
User Comments (0)
About PowerShow.com