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Energy


Western Wind & Solar
Integration Study:
Intra-hour Variability and Operations


Stakeholders Meeting
July 30, 2009
Introduction to Intra-hour Variability

Variability vs. Uncertainty
• Day-ahead forecast error is the major contributor to Uncertainty
• Subhourly changes in net load are the main source of Variability

• Subhourly Variability drives dynamic reserve requirements
• Handling of DAH Uncertainty dominates dynamic reserve capability

• In this section, we will focus on 10-min variability
           o 10 minutes is a good divider between running reserves and cold/standby reserves
           o We have 10-min data




                                                                                          2
Summary Statistics for 10-Minute Net Load Change (Delta)
Footprint -> WECC
          At study footprint
          level, overall 10-
          minute variability
        increase is relatively
                 small




                Severity of most
                extreme changes
                 increases more
                                                           3
        Corrected for 2/3 Data
Summary Statistics for 10-Minute Data




                                        4
        Corrected for 2/3 Data
Summary Statistics for 10-Minute Delta
Zone -> Wyoming -> Footprint -> WECC
Local Priority Scenario




                                         5
        Corrected for 2/3 Data
10-minute Variability: Wind and Net Load (Local Priority Case)

                                   Wind LP 2006
                                         LP, 2006

                     250                                                                        e.g. Average wind
                                                                                               power of top 10% of
                                                                                                                         • Wind variability
                     200                                                                       hours is 20583 MW.          not simply
                                                                                                σ 10-minute Δ for
                                                                                                                           proportional to
  Sigma (MW)




                     150                                                                        these 876 hours is
                                                                                                      168MW                wind power level
                     100
                                                                         Wind (10%)           10% Nameplate       9600
                      50                                                 Wind (20%)           20% Nameplate      18180
                                                                         Wind (30%)           30% Nameplate      26760
                       0
                            0        5000       10000       15000      20000          25000
                                             Average Wind Power (MW)
                                                                                                 e.g. Average net
                                                                                               load power of 2nd to
                                  Net Load* 2006 2006
                                          LP, LP                                                top 10% of hours is      • Variability
                                                                                                    34821 MW.
                      400                                                                        Sigma 10-minute
                                                                                                                           increases with
                      350                                                                       delta for these 876        increased
                                                                                                  hours is 374MW
                      300                                                                                                  penetration
        Sigma (MW)




                      250

                      200                                                                        This curve is load      • Periods of low net
                      150
                                                                         Load Alone
                                                                                                  only variability
                                                                                                                           load tend to have
                      100                                                L-W (10%)                                         considerably more
                       50
                                Min Load: 21249
                                                                         L-W (20%)
                                                                         L-W (30%)
                                                                                                                           variability
                        0
                            0        10000      20000       30000      40000          50000
                                              Net Load Average (MW)

               * For Balance of this portion of the presentation Solar is disregarded: Net Load = Load - Wind
                                                                                                                                              6
10-minute Variability: Wind and Net Load - 3 Scenarios

                                       In Area 2006   IA, 2006
                                                                                                                             Local Priority 2006 Lp, 2006
                                                                                                                                                                                                                                  Mega Project 2006
                                                                                                                                                                                                                                                  MP, 2006

             250                                                                                                   250                                                                                         250


             200                                                                                                   200                                                                                         200
Sigma (MW)




                                                                                                   Sigma (MW)




                                                                                                                                                                                               Sigma (MW)
             150                                                                                                   150                                                                                         150


             100                                                                                                   100                                                                                         100
                                                                              Wind (10%)                                                                                   Wind (10%)                                                                                       Wind (10%)
              50                                                              Wind (20%)                                50                                                 Wind (20%)                                    50                                                 Wind (20%)
                                                                              Wind (30%)                                                                                   Wind (30%)                                                                                       Wind (30%)
                    0                                                                                                    0                                                                                                0
                           0           5000         10000        15000      20000      25000                                     0   5000       10000       15000       20000          25000                                  0       5000       10000       15000       20000          25000
                                                 Average Wind Pow er (MW)                                                                    Average Wind Pow er (MW)                                                                         Average Wind Pow er (MW)




                                                       IA, 2006                                                                                  LP, 2006                                                                                         MP, 2006

                           400                                                                                          400                                                                                              400

                           350                                                                                          350                                                                                              350

                           300                                                                                          300                                                                                              300
                                                                                                           Sigma (MW)
              Sigma (MW)




                                                                                                                                                                                                            Sigma (MW)
                           250                                                                                          250                                                                                              250

                           200                                                                                          200                                                                                              200

                           150                                                                                          150                                                                                              150                                               Load Alone
                                                                              Load Along                                                                                  Load Along
                                                                                                                                                                                                                                                                           L-W (10%)
                           100                                                 L-W (10%)                                100                                               L-W (10%)                                      100
                                                                                                                                                                                                                                                                           L-W (20%)
                            50                                                 L-W (20%)                                 50                                               L-W (20%)                                       50
                                                                                                                                                                                                                                                                           L-W (30%)
                                                                               L-W (30%)                                                                                  L-W (30%)
                               0                                                                                             0                                                                                                0
                                   0     10000        20000       30000     40000          50000                                 0   10000      20000       30000       40000          50000                                      0   10000      20000       30000       40000      50000
                                                    Net Load Average (MW)                                                                     Net Load Average (MW)                                                                            Net Load Average (MW)




                               • Wind shapes vary with spacial diversity
                                  • Mega project more concentrated: looks more like a single plant
                               • Net load trends similar at study footprint level

                                                                                                                                                                                                                                                                                                7
                                              Wind Variability: Normalized to Installed Rating
                                                                          IA, 2006                                                                                               Lp, 2006                                                                                                     MP, 2006
                                                                                                Increasing wind
                        250
                                                                                                  penetration                                            250                                                                                                 250


                        200                                                                                                                              200                                                                                                 200
Sigma (MW)




                                                                                                                                  Sigma (MW)




                                                                                                                                                                                                                                                Sigma (MW)
                        150                                                                                                                              150                                                                                                 150


                        100                                                                                                                              100                                                                                                 100
                                                                                                         Wind (10%)                                                                                         Wind (10%)                                                                                                      Wind (10%)
                                         50                                                              Wind (20%)                                       50                                                Wind (20%)                                        50                                                            Wind (20%)
                                                                                                         Wind (30%)                                                                                         Wind (30%)                                                                                                      Wind (30%)
                                          0                                                                                                                 0                                                                                                  0
                                                0        5000           10000          15000         20000          25000                                       0   5000       10000        15000       20000        25000                                         0          5000            10000      15000        20000             25000
                                                                     Average Wind Pow er (MW)                                                                               Average Wind Pow er (MW)                                                                                    Average Wind Pow er (MW)

                                                         10% Nameplate                      10290                                                                   10% Nameplate                    9600                                                                   10% Nameplate                       8700
                                                         20% Nameplate                      19950                                                                   20% Nameplate                   18180                                                                   20% Nameplate                      16260
                                                         30% Nameplate                      29940                                                                   30% Nameplate                   26760                                                                   30% Nameplate                      24030
                                                                                                                                                                                 LP, 2006                                                                                                     MP, 2006
                                                                          IA, 2006
                                                                                            Increasing wind
                                                                                              penetration
                                                                                                                                                                                                                                                       1.00
                                         1.00                                                                                                            1.00
                                                                                                                                                                                                                                                       0.90
                                         0.90                                                                                                            0.90
                                                                                                                             Sigma (Percent of Rating)




                                                                                                                                                         0.80                                                                                          0.80




                                                                                                                                                                                                                           Sigma (Percent of Rating)
                                         0.80
             Sigma (Percent of Rating)




                                         0.70                                                                                                            0.70                                                                                          0.70

                                         0.60                                                                                                            0.60                                                                                          0.60

                                         0.50                                                                                                            0.50                                                                                          0.50
                                         0.40                                                                                                            0.40                                                                                          0.40
                                         0.30                                                                                                            0.30                                                Wind (10%)                                0.30                                                                      Wind (10%)
                                                                                                           Wind (10%)
                                         0.20
                                                                                                                                                         0.20                                                Wind (20%)                                                                                                          Wind (20%)
                                                                                                           Wind (20%)                                                                                                                                  0.20
                                         0.10                                                              Wind (30%)                                    0.10                                                Wind (30%)                                                                                                          Wind (30%)
                                                                                                                                                                                                                                                       0.10
                                         0.00
                                                                                                                                                         0.00
                                                0   10          20       30       40       50       60       70         80                                      0    20           40           60           80            100 0.00
                                                                                                                                                                                                                                                              0        10      20        30      40      50      60         70     80         90
                                                                Average Wind Power (Percent of Rating)                                                                Average Wind Pow er (Percent of Rating)
                                                                                                                                                                                                                                                                                    Average Wind Power(Percent of Rating)




                                                                              • Higher penetration – relatively less variability
                                                                              • Wider distribution – less variability and less dependence
                                                                                on wind level
                                                                                                                                                                                                                                                                                                                                   8
            What do we do with σΔ 10-min?
                                 LP 3%
            What is relationship to2006 of load for spinning reserve?
                          0.70     Study Footprint LP σΔ 10-min                                                           Relationship between 10-min
                          0.60                                                                                              load delta and present spin
                                                                                                                            practice (3% rule):
Sigma (Percent of Peak)




                          0.50

                          0.40                                                                                            • Load variability roughly
                          0.30                                                                                              proportional to Load level
                          0.20                 : 1%
                                                                                                   Load Alone               (up to moderately high
                                             pe                                                                             loads
                                       Slo
                                                                                                       L-W (10%)
                          0.10                                                                         L-W (20%)

                          0.00
                                                Min Load: 37%                                          L-W (30%)
                                                                                                                          • On a large area basis (e.g.
                                 0.0    10.0        20.0    30.0      40.0    50.0     60.0     70.0       80.0    90.0
                                                                                                                            AZ), proportionality is ~ 1%
                                                                                                                            of load
                                                           Net Load Average (Percent of Peak)

                                                                   AZ LP 2006
                                                                                                                          • Therefore, 3% of load rule
                                   Arizona LP σΔ 10-min
                          0.80
                                                                                                                            roughly corresponds to 3σ
                          0.70
                                                                                                                            of 10-min variability
Sigma (Percent of Peak)




                          0.60

                          0.50                                                                                            • We will build on this
                          0.40                                                                                              relationship, that is:
                                                                                                         Load Alone
                          0.30                                                                            L-W (10%)       For all operating conditions
                                               1%                                                         L-W (20%)
                                                                                                                            there is an implied reserve
                                           pe:
                          0.20
                                       Slo                                                                L-W (30%)
                          0.10
                                                                   AZ Min Load: 31%                                         requirement: 3 x σ 10-min
                          0.00
                                 0.0    10.0        20.0    30.0      40.0    50.0     60.0     70.0       80.0    90.0
                                                                                                                            Δ Net Load
                                                                                                                                                       9
                                                           Net Load Average (Percent of Peak)
                                                                                                                                        What is this plot ???
 L30 Load - Wind - Net Load Relationship
                                                                                                                                        a.            Each year has 8760
                                                                                Net Load (MW)                                                         hours.
                          Lines of Constant                     p                                      50000-60000                      b.            Load varies
                              Net Load                                                                 40000-50000                                    between a
                                                          LP Net Load Space                                                                           minimum and
                                                                          S11                          30000-40000                                    maximum
26760 MW                                                                                               20000-30000                      c.            Wind power varies
                                                                          S10
(Max Wind)                                                                                             10000-20000                                    between zero and a
                                                                                                                                                      maximum
                                                                          S9                           0-10000                          d.            The range of load
        99%
                                                                          S8                           -10000-0                                       and wind are each
                                                                                                                                                      divided into 10
 90% of                                                                                                                                               equal sized buckets
                                                                          S7




                                                                                      Wind Level
 time, wind                                                                                                                             e.            So, there are 100
 is less than                                                             S6                                                                          combinations of
 18231 MW                                                                                                                                             load & wind
                                                                          S5                                                            f.            The value (color) at
Number of hours                                                                                                                                       each intersection is
                                                                          S4                                                                          the Net Load for
  in each cell
 varies: in L30                                                                                                                                       that combination
                                                                          S3
 case, this cell                                                                                       60000
                                                                                                                                                                         Study_Area Baseline

 includes 153
                                                                                                                                                                         Study_Area L-W-S (10%)
                                                                          S2                           50000
                                                                                                                                                                         Study_Area L-W-S (20%)

     hours.                                                                                            40000
                                                                                                                                                                         Study_Area L-W-S (30%)


                                                                                                                                                                  Load range




                                                                                 Net Load Level (MW)
                      )                                                    S1
                                                                                                       30000
                          1    2    3    4    5   6   7    8   9    10   11

                                   Load Level
                                                                                                       20000


                                                              99%
                                                      Load Level                                       10000
                                                                                                                                               70% of
                   21249 MW                       90% of       58087 MW                                    0
                                                                                                                                               range
                   (Min Load)                     time, load   (Peak Load)                             -10000
                                                                                                                0   583   1166   1749        2332   2915   3498   4081      4664     5247      583

                                                  is less than
                                                  43308 MW                                                                              10% of hours:
                                                                                                                                          876 hr/yr                                   10
Operations L30: Hours of Load & Wind Combinations

                          L30 Hours of Operation (per year)


                                                       S10
                                                                            No data: the

                                                       S9
                                                                           system “Never”
                                                                            operates here
                                                                                            Hours/year
                                                                                              500-550
                                                       S8                                     450-500
                                                                                              400-450
                                                       S7
                                                                                              350-400




                                                              Wind Level
                                                       S6                                     300-350
                                                              Wind Level                      250-300
                                                       S5
                                                                                              200-250
                                                       S4                                     150-200
                                                                                              100-150
                                                       S3                                     50-100
                                                                                              0-50
                                                       S2
                                                                                               Never
                                                                                              -50-0
                                                      S1
          1   2   3   4   5    6      7    8    9   10

                  Load Level System spends
                       Load Level

                                   the most time
                                    at this load
                                   and wind level                                                        11
Load Only Variability L30
                                                                  (bla
                                             10-minute Δσ
                                                   450-500
                                                                                    • Load variability
                                                                                      highest at
                                                                  10
                                                   400-450
                                                   350-400
                                                                  9
                                                                                      moderate loads
                                                   300-350
                                                   250-300                          • Dominated by
                                                   200-250
                                                   150-200
                                                                  8
                                                                                      diurnal load cycle
                                                   100-150
                                                                  7
                                                   50-100




                                                                       Wind Level
                                                    Never
                                                   0-50
                                                                  6



                                                                  5



                                                                  4



                                                                  3



                                                                  2



                                                                  1
   1   2    3   4      5    6    7   8   9    10      #N/A   (blank)


                    Load Level
                                                                                                      12
Wind Only Variability L30
                                                                        10-minute Δσ

•   Wind variability                                                         450-500        (bla

                                                                             400-450
    appears to be                                                            350-400        10
    affected by load                                                         300-350

    level                                                                    250-300
                                                                             200-250        9


•   Not Intuitive                                                            150-200
                                                                             100-150        8

•   But maybe it                                                             50-100
                                                                              Never
    makes sense…                                                             0-50
                                                                                            7


•   Diurnal patterns




                                                                                                   Wind Level
                                                                                            6
    suggest wind is
    more variable                                                                           5

    during periods of
    high load: i.e.                                                                         4

    during the day
                                                                                            3



                                                                                            2



                                                                                            1
                            1   2   3   4   5     6   7      8     9    10    #N/A     (blank)
                                                          10% of time

                                                Load Level
                                                                                                   13
Net Load Variability L30
                                                                10-minute Δσ
                                                                   450-500       (blank)
• Net load                                                         400-450

variability                                                        350-400
                                                                   300-350
                                                                                 10

increases with                                                     250-300

wind
                                                                   200-250       9
                                                                   150-200
                                                                   100-150
• Implied reserve                                                  50-100
                                                                                 8

requirement is 3 x                                                  Never
                                                                   0-50
                                                                                 7
Δσ




                                                                                     Wind Level
                                                                                 6
• Requirement is a
function of both                                                                 5

load level and
wind level                                                                       4


                                                                                 3


                                                                                 2


                                                                                 1
                      1    2   3   4    5   6       7   8   9    10    #N/A (blank)

                                       Load Level
                                                                                              14
Intra-hour Variability Performance


•   How did the system ‘naturally’ in MAPS perform?
•   We show how L30R MAPS case results compare to implied
    reserve requirements.




                                                            15
Average Up Range L30R case
                                                     Ave Up Range MW
                                                               12000-14000
                                            S10                10000-12000
                                                               8000-10000
                                            S9                 6000-8000
                                                               4000-6000

                                            S8                 2000-4000
                                                               0-2000
                                                                 Never
                                                               -2000-0
                                            S7




                                                  Wind Level
                                            S6                      • Up reserves tend to
                                            S5                      be reduced at high
                                                                    load levels
                                            S4
                                                                    • Up reserves tend to
                                            S3
                                                                    increase with wind
                                            S2                      power: reduction in
                                             S1                     unit dispatch more
      1   2   3    4   5   6   7   8   9   10                       than compensates for
                  Load Level                                        unit de-commitments


                                                                                            16
L30R Case Up Reserve Violations                         LP30 UpRange Margin - Worst Hour


                                                                        S10

 • Implied reserve                                                      S9
                                                                                    Worst Violation (MW)
 requirement is 3 x σ 10-                                               S8
                                                                                                Never
                                                                                                200-400

 min Δ Net Load                                                         S7                      None
                                                                                                0-200
                                                                                                -200-0
                                                                        S6
                                                                              Wind Level        -400--200
 • Violation if Up Range                                                S5
                                                                                                -600--400

 (from MAPS case) < 3σ                                                  S4                      -800--600
                                                                        S3                      -1000--800

 • Violation means hour                                                 S2

 has insufficient reserves    1   2   3   4     5   6      7   8   9   10
                                                                         S1


 to meet implied                              Load Level
                              LP30 Count of Up Range Margin Violations
 requirement. Load is                                                S10

 still served.                                                          S9
                                                                        S8
                                                                        S7
                                                                                              Hours of Violation
                                                                        S6
                                                                              Wind Level                  30-40
    Scarcity of reserves at                                             S5
                                                                                                          20-30
    very high load                                                      S4
                                                                               Total Count                10-20
                                                                                  Total Count of
    aggravated by increased                                             S3        Violations:
                                                                               of Violations: 132         0-10

    reserve requirement due                                             S2     132                        None
                                                                                                          -10-0

    to wind variability       1   2   3   4     5   6      7   8   9   10
                                                                         S1                Up reserves
                                                                                           most scarce
                                              Load Level
                                                                                                                  17
L30R Case Down Reserve Violations
                                              LP 30 Down Spin Margin - Worse Hour

                                                                     S10
                                                                     S9
                                                                     S8
                                                                     S7

• Scarcity of down                                                   S6
                                                                           Wind Level
                                                                                                           30000-40000
                                                                     S5                                    20000-30000
reserves at very high                                                S4                                    10000-20000
wind and relatively light                                            S3                                    0-10000

load is consistent with                                              S2
                                                                    S1
                                                                                                           -10000-0

other results                1   2 3     4     5 6     7      8 9 10
                                         Load Level

                                             Count of Down Violations

                                                                     S10
                                                                     S9
                                                                     S8
                                                                     S7                         4.0-5.0

                                                                     S6                         3.0-4.0
                                                                           Wind Level           2.0-3.0
                                                                     S5
                                                                                                1.0-2.0
                                                                     S4              Count
                                                                             Total 8 hours of
                                                                               Total            0.0-1.0
                                                                     S3      of Violations:
                                                                                  Violations    None
                                                                                                -1.0-0.0
                                                                     S2      8
                                                                      S1
                             1   2   3   4     5   6      7   8   9 10
                                             Load Level                                                               18
  Arizona & Wyoming: Average (MW) vs Sigma of 10-min Delta (MW)

                  140              Arizona Wind                                                                                140                                                        Wyoming
                  120                                                                                                          120                                                        Wind
                  100                                                                                                          100




                                                                                                              Sigma (MW)
Sigma (MW)




                          80                                                                                                            80

                          60                                                                                                            60

                          40                                                              Wind (10%)                                    40                                                        Wind (10%)
                                                                                          Wind (20%)                                                                                              Wind (20%)
                          20                                                                                                            20
                                                                                          Wind (30%)                                                                                              Wind (30%)
                           0                                                                                                             0
                               0                2000             4000              6000                8000                                  0           2000               4000           6000                8000
                                                        Average Wind Pow er (MW)                                                                                Average Wind Pow er (MW)
                                                                                                              Peak Load                             4016
                          180
                                       Arizona Net Load
                                                                                                              Min Load
                                                                                                              10% Nameplate
                                                                                                                                             Wyoming2369
                                                                                                                                                    1650
                                                                                                                                                                      140
                                                                                                                                                                                              Load Alone
                          160                                                                                 20% Nameplate                  Net Load
                                                                                                                                                    4020              120
                                                                                                                                                                                                  L-W (10%)
                          140                                                                                 30% Nameplate                         7410
                                                                                                                                                                      100                         L-W (20%)
                          120




                                                                                                                           Sigma (MW)
             Sigma (MW)




                                                                                                                                                                                                  L-W (30%)
                                                                                                                                                                       80
                          100
                           80                                                        Load Alone                                                                        60
                           60           Peak Load             23051                  L-W (10%)                                                                         40
                           40           Min Load               6995
                                                                                     L-W (20%)
                                        10% Nameplate          2850                                                                                                    20
                           20           20% Nameplate          5250                  L-W (30%)

                               0
                                        30% Nameplate          7710                                                                                                     0
                                   0            5000             10000        15000               20000                                 -6000    -4000      -2000           0      2000       4000        6000

                                                             Average (MW)                                                                                           Average (MW)


                                       • At area level wind impact is more observable
                                       • By the time that we get to a very high system like Wyoming, wind
                                         dominates                                                                                                                                                              19
Arizona L30R results




                       20
 Arizona L30R Load Variability

                                                                             (blank)


                                                                             10
 99%
                                                                             9
                                                                                                10-minute Δσ
                                                                             8
                                                                                                   450-500
90% of                                                                                             400-450
time, wind                                                                   7                     350-400
is less than                                                                                       300-350




                                                                                   Wind Level
6404 MW                                                                      6                     250-300
                                                                                                   200-250
                                                                             5                     150-200
                                                                                                   100-150
                                                                                                   50-100
                                                                             4
                                                                                                   0-50

                                                                             3
                                                                                      • AZ load relatively
                                                                             2          unaffected by
                                                                             1
                                                                                        wind level
               1   2     3   4      5      6    7    8   9     10   #N/A (blank)

                       Load Level       90% of
                                                         99%
                                        time, load
                                        less than
                                        16590 MW
                                                                                                               21
Arizona L30R Wind Variability

                                                           (blank)


                                                           10


                                                           9
                                                                                  10-minute Δσ
                                                           8                         450-500
                                                                                     400-450
                                                           7                         350-400
                                                                                     300-350




                                                                     Wind Level
                                                           6                         250-300
                                                                                     200-250
                                                                                     150-200
                                                           5
                                                                                     100-150
                                                                                     50-100
                                                           4                         0-50

                                                           3
                                                                     • AZ wind variability
                                                           2           highly dependent
                                                                       on load level:
                                                           1
    1   2   3   4     5   6      7   8   9   10   #N/A (blank)         diurnal effects
                                                                       apparent

                    Load Level
                                                                                                 22
Arizona L30R Net Load Variability
                                                    (blank)


                                                    10


                                                    9

                                                                      10-minute Δσ
                                                    8
                                                                         450-500
                                                                         400-450
                                                    7
                                                                         350-400




                                                         Wind Level
                                                                         300-350
                                                    6                    250-300
                                                                         200-250
                                                    5                    150-200
                                                                         100-150
                                                    4                    50-100
                                                                         0-50

                                                    3

                                                                      • AZ net variability a
                                                    2
                                                                        mix of wind and
                                                    1
                                                                        load impacts
1   2   3   4    5   6   7   8   9   10   #N/A (blank)

                Load Level


                                                                                               23
Arizona L30R Case up Reserve Violations

                                                                     AZ Worst Up Reserve Violation


                                                                                                       S9

   • Worst violations                                                                                  S8
                                                                                                            Worst Violation (MW)
   at high load and
                                                                                                       S7
                                                                                                                       Never
                                                                                                                       200-400
                                                                                                       S6              None
   moderate wind
                                                                                                                       0-200

                                                                                                       S5 Wind Level   -200-0
                                                                                                                       -400--200
                                                                                                       S4
   • Frequent                                                                                          S3
                                                                                                                       -600--400
                                                                                                                       -800--600
   violations at low                                                                                   S2              -1000--800


   wind moderate                        1   2    3       4       5       6       7       8   9    10
                                                                                                    S1


   load: due to                                              Load Level


   Forecast error (?)                   L30 Arizona count of Up reserve violations
                                                                                                 S10
                                                                                                 S9
                                                                                                 S8            Hours of Violation
                                                                                                 S7                                 50-60
                                                                                                 S6                                 40-50
                                                                                                       Wind Level                   30-40
                                                                                                 S5
                                                                                                                                    20-30
                                                                                                 S4
                                                                                                                                    10-20
                                                                                                 S3
                                                                                                                                    0-10
                                                                                                 S2
                                                                                             S1
                                                                                                        Total Count
                                                                                                       Total757 Hours of            None
                                                                                                                                    -10-0

                  Up reserves short     1   2   3    4       5       6       7       8   9 10          of Violations:
                                                                                                            Violations

                 due to over-forecast                Load Level                                        757
                   of wind power ?
                                                                                                                                            24
Wyoming L30R results




                       25
 Wyoming L30R Wind Variability
                                                            10-minute Δσ
                                                                           (blank)
                                                                450-500
                                                                400-450
                                                                           10
                                                                                             • Wind variability
 99%                                                            350-400
                                                                300-350
                                                                                             slightly dependent
                                                                250-300    9                 on load level –
                                                                200-250
                                                                150-200    8
                                                                                             except at very high
90% of                                                          100-150                      loads (small
time, wind
is less than
                                                                50-100
                                                                0-50
                                                                           7
                                                                                             sample?)




                                                                                Wind Level
6780 MW                                                                    6
                                                                                             • High variability at
                                                                           5                 middle of wind
                                                                                             power range is an
                                                                           4
                                                                                             expected
                                                                           3                 characteristic
                                                                           2
                                                                                         ~ 0.1% of data:
                                                                          1
                                                                                         Variability may
               1   2   3   4    5   6   7        8   9     10   #N/A (blank)             be over(under)
                                                                                              stated
                   Load Level       90% of
                                                     99%
                                    time, load
                                    less than
                                    3553 MW
                                                                                                               26
Wyoming L30R Load Variability

                                                     (blank)


                                                     10
                                                                              Note
                                                     9                        scale

                                                     8




                                                           Wind Level
                                                     7


                                                     6
                                                                              20.0-25.0
                                                                              15.0-20.0
                                                     5
                                                                              10.0-15.0
                                                                              5.0-10.0
                                                     4                        0.0-5.0

                                                     3
                                                                        • Load variability
                                                     2                  basically
                                                                        insignificant
                                                     1
  1   2   3   4   5   6   7    8   9   10   #N/A (blank)                compared to wind
                  Load Level                                            variability

                                                                                             27
Wyoming L30R Net Load Variability
                                                          10-minute Δσ
                                                                  450-500
                                                    (blank)
                                                                  400-450
                                                                  350-400
                                                    10
                                                                  300-350

                                                    9
                                                                  250-300   • Net Load
                                                                  200-250
                                                                  150-200   variability totally
                                                    8             100-150
                                                                  50-100
                                                                            dominated by
                                                    7
                                                                  0-50      wind variability
                                                    6




                                                          Wind Level
                                                    5


                                                    4


                                                    3

                                                              ~ 0.1% of data:
                                                    2
                                                              Variability may
                                                              be overstated
                                                    1
1   2   3   4    5   6   7   8   9   10   #N/A (blank)


                Load Level

                                                                                                  28
Wyoming L30R Time Space


                                                    Wyoming


• Wyoming wind                                                      S10

bi-modal:                                                           S9
                                                                                       Hours/yr
                                                                    S8
Relatively light                                                                        300-350
                                                                    S7
wind or relatively                                                                      250-300
                                                                    S6
strong wind                                                               Wind Level
                                                                                        200-250
                                                                    S5                  150-200

• Periods of                                                        S4
                                                                                        100-150

highest implied                                                     S3
                                                                                        50-100
                                                                                        0-50
reserve                                                             S2                  -50-0
requirements are                                                     S1
less common,              1   2   3   4     5   6      7   8   9   10

but…                                      Load Level




                                                                                                  29
Wyoming L30R Case up Reserve Violations
                                     Wyoming Worst Ur Reserve Violations

                                                                         S10
                                                                         S9        Worst Violation (MW)
                                                                         S8                 Never
                                                                                            200-400
                                                                                            None
• Wyoming, with
                                                                         S7                 0-200
                                                                         S6                 -200-0

about twice as                                                           S5
                                                                               Wind Level
                                                                                            -400--200
                                                                                            -600--400
much wind as load,                                                       S4
                                                                         S3                 -800--600

doesn’t come close                                                       S2                 -1000--800

to meeting implied               1   2     3   4     5   6   7   8   9 10
                                                                         S1


reserve                                            Load Level

requirement with                         Wyoming L30 Count of Violations
                                                                                   Hours of Violation
in-state resources                                                      S10                 160-180

in this case                                                            S9                  140-160
                                                                        S8                  120-140
                                                                        S7                  100-120
                                                                        S6                  80-100
                                                                               Wind Level
                                                                        S5                  60-80
                                                                        S4                  40-60
                                                                        S3                  20-40

                                                                        S2                  0-20


                                 1   2     3   4     5   6   7   8   9 10
                                                                         S1      Total Count of
                                                                                  2075 Total Hours of
                                                                                      Violations
                                               Load Level
                                                                                 Violations: 2075
                                                                          100% of hours at Load
                                                                            Level 8 in violation          30
Intra-hour Variability - Summary

• Intra-hour variability increases with wind
• Smaller the ‘circle’, bigger the effect
• On FP or WECC level, variability ‘looks’ similar..change is
  incremental, not revolutionary
• On Area (state) level, variability starts to look very
  different…eventually dominated completely by wind (e.g. WY)
• On smaller (e.g. zonal) basis, variability clearly intractable…2 orders
  of magnitude increase…old rules unsuitable/impossible
• Examination of subhourly performance suggests that rationally
  committed and dispatched systems, using imperfect DAH wind
  forecasts, can work well, if reserve resources are shared.
• Modified (usable, practical) rules for spin appear possible




                                                                            31
Intra-hour Variability – Next Steps

• Develop additional understanding of implications of day
  ahead wind forecast error on reserve capabilities
• Examine other states, scenarios and renewable levels
• Expand concepts to solar
• Test implications of reserve sharing on inter-area
  performance, particularly CPS2
• Explore concepts for addressing inter-area performance
  issues
• Examine allocation of reserve resources, by generation type
  and dynamic capability
• Test performance with QSS time simulations
• Further develop concepts for modified, simple rules for
  spinning reserves




                                                                32