Evaluating Hydro Capacity for Capacity Adequacy Standard:

Selection of Hydro Events

Mary JohannisMary JohannisPNW Resource Adequacy Technical Committee MtgPNW Resource Adequacy Technical Committee Mtg

November 27, 2007November 27, 2007

November 27, 2007

PNW Resource Adequacy Technical Committee Meeting 2

Why Evaluate Hydro Capacity

• Regional Capacity Adequacy Assessment performed by Council

• WECC Loads and Resource Reporting by Balancing Authorities

• PNUCC Reporting

• Individual Utility Resource Planning

November 27, 2007

PNW Resource Adequacy Technical Committee Meeting 3

Steps to Finalize Capacity Adequacy Standard

• Validate & Calibrate GENESYS Model• Select Threshold(s) in GENESYS that define

bad events Region wants to avoid• Select Sustained Peaking Period for

Capacity Metric (i.e. Planning Reserve Margin)

• Agree how to count resources toward satisfying Capacity Adequacy Standard– HYDRO – WIND– THERMAL– CONTRACTS

UnderwayUnderway

Done

Underway

November 27, 2007

PNW Resource Adequacy Technical Committee Meeting 4

Calculation of Sustained Hydro Peaking CapacityH

ydro

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n 18 hour Sustained Peaking Duration: Decide for what months to evaluate Capacity Adequacy Standard--February and July? Using expected loads 1/, select peak day & peak hour for winter & summer months. Hydro capacity to be evaluated for 6 highest hours around peak for 3 continuous days with highest

average peak

1 in 20 year Probability Event: Select a historical year and month for both summer & winter, which have approximately a 5% probability of

occurrence based on combined adverse temperature-induced load and adverse hydro conditions. Decide whether different events are needed to evaluate hydro located in Columbia Basin, Willamette Basin

and/or West-side streams.

Evaluate Maximum Hydro Capability over 3 Day Event: Evaluate maximum hydro capability by increasing load to maximize generation possible over peak hours,

constrained by physical/operational constraints and maximum allowable purchases assumed duringshoulder and off-peak hours.

For the winter event, maximize hydro generation over both peaks of the daily load curve. Decide on appropriate off and shoulder peak purchase assumptions. Define NON-EMERGENCY heat-wave and cold-snap operations (e.g. for the FCRPS, Coulee is drafted up

to 2 feet/day and Dworshak generates at full output during winter cold snap). Sum hourly hydro generation for highest 6 consecutive hours over 3 days and divide by 18. This is sustained hydro peaking capacity and is maximized for system capability not planned to load.

1/ i.e. temperature neutral loads

November 27, 2007

PNW Resource Adequacy Technical Committee Meeting 5

Historical vs. CalculatedSustained FCRPS Peaking Capacity

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s Historical Cold Snap Hydro

Expected Load

CalculatedSustained FCRPS Cap

Purchases PurchasesCapto meet

ExpectedLoad

Surplus + Cap to

meet PRM

November 27, 2007

PNW Resource Adequacy Technical Committee Meeting 6

Alignment with LOLP = 5%

• Approach:– Plan hydro capacity to assure sufficient capacity available

to meet load 95% of time.– Plan hydro capacity to meet load under 1 in 20 probability

event• Adverse hydro• Adverse temperature-induced load

• Select regional summer and winter hydro condition– For WECC and Resource Adequacy Forum reporting, the

selection of hydro condition for which to report hydro capacity assures consistency

– Utilities could then define temperature-induced adverse load conditions for their own resource planning efforts which approximate 1 in 20 probability event

November 27, 2007

PNW Resource Adequacy Technical Committee Meeting 7

Representative NW Hydro Projects

ROSS

Round Butte

Columbia River Hydro

November 27, 2007

PNW Resource Adequacy Technical Committee Meeting 8

Suggested Representative Projects

• FCRPS– FCRPS not very sensitive to Selection of

Adverse Event

• Non-Columbia River Projects – PGE’s Round Butte Project on Deschutes

River is representative of Williamettes– Seattle’s ROSS on Skagit River is a

representative West-side project

November 27, 2007

PNW Resource Adequacy Technical Committee Meeting 9

Selecting Adverse Hydro Condition for Winter Event

• Approach– Look at candidate

events, which represent more or less adverse hydro conditions

– Investigate events with February flows within 1 standard deviation (α) lower than mean

– Pick event which Region believes is most reasonable

• Candidate Feb Events– 1936-37 = reference, not

candidate event– 1968-69 = 1 standard

deviation below mean for Williamettes & Westside; adverse for Columbia R.

– 1988-89 = less adverse for Williamettes & Westside; 1 standard deviation for Columbia R.

– 1945-46 = somewhat adverse for all

November 27, 2007

PNW Resource Adequacy Technical Committee Meeting 10

Water Year

Unreg Feb Flows (cfs)

Water Year

Unreg Feb Flows (cfs)

Water Year

Unreg Feb Flows (cfs)

1.41% 1931 - 32 3,025 1936 - 37 462 1936 - 37 50,4182.82% 1963 - 64 3,390 1928 - 29 499 1935 - 36 50,4494.23% 1940 - 41 3,457 1935 - 36 575 1993 - 94 55,6805.63% 1930 - 31 3,619 1984 - 85 705 1928 - 29 57,0377.04% 1932 - 33 3,619 1943 - 44 865 1930 - 31 58,0678.45% 1936 - 37 3,673 1968 - 69 878 1943 - 44 59,5769.86% 1939 - 40 3,790 1965 - 66 887 1976 - 77 60,130

11.27% 1935 - 36 3,912 1955 - 56 890 1931 - 32 61,35312.68% 1928 - 29 3,925 1941 - 42 936 1938 - 39 61,40014.08% 1968 - 69 3,925 1992 - 93 939 1992 - 93 61,57915.49% 1992 - 93 4,024 1932 - 33 955 1987 - 88 62,56516.90% 1993 - 94 4,030 1972 - 73 956 1932 - 33 63,43818.31% 1929 - 30 4,051 1978 - 79 957 1988 - 89 64,68919.72% 1941 - 42 4,051 1938 - 39 962 1963 - 64 66,589

21.13% 1934 - 35 4,069 1937 - 38 1,028 1965 - 66 70,99022.54% 1991 - 92 4,241 1948 - 49 1,036 1972 - 73 71,22723.94% 1988 - 89 4,267 1987 - 88 1,057 1954 - 55 73,39825.35% 1938 - 39 4,303 1974 - 75 1,065 1940 - 41 73,91526.76% 1990 - 91 4,319 1993 - 94 1,128 1984 - 85 73,94928.17% 1937 - 38 4,339 1945 - 46 1,155 1945 - 46 81,09829.58% 1989 - 90 4,349 1947 - 48 1,199 1986 - 87 81,44330.99% 1944 - 45 4,357 1954 - 55 1,208 1937 - 38 81,73832.39% 1947 - 48 4,398 1988 - 89 1,245 1979 - 80 84,32933.80% 1945 - 46 4,465 1977 - 78 1,294 1978 - 79 84,75635.21% 1987 - 88 4,572 1951 - 52 1,311 1974 - 75 84,76136.62% 1943 - 44 4,590 1942 - 43 1,336 1989 - 90 85,45738.03% 1959 - 60 4,659 1940 - 41 1,408 1944 - 45 85,52639.44% 1965 - 66 4,664 1949 - 50 1,449 1939 - 40 88,31540.85% 1933 - 34 4,718 1956 - 57 1,452 1968 - 69 92,12042.25% 1954 - 55 4,718 1997 - 98 1,473 1929 - 30 92,49343.66% 1967 - 68 4,729 1976 - 77 1,539 1941 - 42 94,80945.07% 1948 - 49 4,736 1986 - 87 1,552 1977 - 78 95,12146.48% 1949 - 50 4,754 1963 - 64 1,555 1956 - 57 96,80647.89% 1966 - 67 4,790 1958 - 59 1,558 1961 - 62 98,41049.30% 1976 - 77 4,790 1998 - 99 1,586 1955 - 56 98,63650.70% 1946 - 47 4,844 1989 - 90 1,602 1991 - 92 99,16552.11% 1961 - 62 4,988 1939 - 40 1,639 1934 - 35 100,13853.52% 1986 - 87 4,988 1969 - 70 1,651 1947 - 48 101,06254.93% 1972 - 73 5,168 1973 - 74 1,726 1959 - 60 101,22956.34% 1951 - 52 5,198 1979 - 80 1,778 1948 - 49 102,35457.75% 1984 - 85 5,222 1959 - 60 1,882 1966 - 67 103,225

The DallesProbability of Occurrence

Round Butte ROSS

November 27, 2007

PNW Resource Adequacy Technical Committee Meeting 11

February18-hour Federal Hydro Generation and Natural Streamflows

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1936 - 37

1943 - 44

1987 - 88

1972 - 73

1986 - 87

1989 - 90

1941 - 42

1991 - 92

1966 - 67

1997 - 98

1946 - 47

1990 - 91

1960 - 61

1994 - 95

1995 - 96

Historical YearsRanked by Hydro Condition

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Feb 1968-69Nat Flow

Standard Deviation

November 27, 2007

PNW Resource Adequacy Technical Committee Meeting 12

Next Steps• Agree on Approach for evaluating regional hydro

capacity both in summer & winter• If hydro capacity is to be evaluated for single

historical summer & winter event, agree on candidate events to be evaluated (still need research on summer events)

• FCRPS to be evaluated by BPA in-house• Options for evaluating non-Federal Hydro Capacity

– Each hydro utility to evaluate– Hire consultant to evaluate, or assist with evaluation through

Technical Committee Subgroup– Possible consultants:

• Columbia Vista Vendor• Other Consultant