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ERC
OT
Win
d Im
pact
/ In
tegr
atio
n A
naly
sis
Febr
uary
27,
200
8
2/
Pro
ject
Sco
pe
Eva
luat
e th
e im
pact
s of
win
d de
velo
pmen
t in
the
ER
CO
T sy
stem
on
anci
llary
ser
vice
s re
quire
men
ts
and
rela
ted
prac
tices
.S
peci
fical
ly:
•E
valu
ate
the
suita
bilit
y of
ER
CO
T’s
exis
ting
prac
tices
for d
eter
min
ing
A/S
pro
cure
men
t•
Rec
omm
end
impr
ovem
ents
to a
ccom
mod
ate
win
d pe
netra
tion
•D
eter
min
e am
ount
and
est
imat
ed c
ost o
f A/S
re
quire
men
ts fo
r var
ious
win
d sc
enar
ios
•R
ecom
men
d pr
oced
ures
for i
mpe
ndin
g se
vere
w
eath
er
3/
A F
ew W
ords
Abo
ut N
et L
oad
Net
Loa
dis
the
inst
anta
neou
s sy
stem
co
nsum
er lo
ad, m
inus
the
gene
ratio
n ou
tput
of
non-
disp
atch
able
win
d ge
nera
tion
Net
load
*is
the
amou
nt o
f gen
erat
ion
requ
ired
from
dis
patc
habl
e un
its
The
stud
y is
con
cent
rate
d on
net
load
, ins
tead
of
the
win
d ge
nera
tion
in is
olat
ion,
bec
ause
so
me
amou
nt o
f the
var
iatio
ns in
eac
h ca
ncel
*N
et lo
ad is
als
o ca
lled
“Loa
d –
Win
d” in
par
ts o
f thi
s pr
esen
tatio
n
4/
Pro
ject
Ove
rvie
w
Pha
se 1
-N
et L
oad
Var
iabi
lity
and
Pre
dict
abilit
y C
hara
cter
izat
ion
Obj
ectiv
e is
to o
btai
n fu
ndam
enta
l qua
litat
ive
and
quan
titat
ive
info
rmat
ion
on
the
char
acte
ristic
s an
d pr
edic
tabi
lity
of n
et lo
ad in
the
ER
CO
T sy
stem
.–
Com
paris
on o
f win
d de
velo
pmen
t sce
nario
s–
Cor
rela
tions
of v
aria
bilit
y an
d pr
edic
tabi
lity
with
load
leve
l, se
ason
, tim
e of
day
The
insi
ghts
obt
aine
d in
this
ana
lytic
inve
stig
atio
n he
lp to
iden
tify
syst
em
oper
atin
g ch
alle
nges
and
det
erm
ine
whe
n th
ey w
ill o
ccur
Pha
se 2
-A
ncilla
ry S
ervi
ces
Eva
luat
ion
Eva
luat
e A
/S re
quire
men
ts a
nd re
com
men
d im
prov
emen
ts to
ER
CO
T’s
A/S
pr
oced
ures
–A
/S re
quire
men
ts a
s a
func
tion
of w
ind
pene
tratio
n–
Eva
luat
e ex
istin
g m
etho
dolo
gies
to d
eter
min
e A
/S n
eede
d–
Rec
omm
end
chan
ges
to a
ccom
mod
ate
win
d–
Eva
luat
e an
d im
prov
e pr
actic
es fo
r im
pend
ing
seve
re w
eath
er
5/
Ana
lysi
s A
ppro
ach
•C
onst
ruct
sys
tem
load
, win
d ge
nera
tion,
and
ne
t loa
d m
odel
tim
e se
ries
data
base
•Ti
me
serie
s an
alys
is–
Cha
ract
eriz
e im
pact
on
load
cur
ve–
Dai
ly m
axim
a an
d m
inim
a–
Net
load
ram
p ra
tes
•S
tatis
tical
ana
lysi
s of
var
iabi
lity
–A
naly
ze v
aria
tions
ove
r diff
eren
t tim
efra
mes
–A
naly
sis
of o
pera
ting
perio
ds w
ith p
artic
ular
cha
lleng
es•
Mod
el a
nd a
naly
ze re
gula
tion
requ
irem
ents
–R
egul
atio
n re
quire
men
ts–
Reg
ulat
ion
proc
urem
ent p
roce
dure
•E
xtre
me
win
d an
alys
is –
resp
onsi
ve re
serv
es
•A
naly
sis
of d
ay-a
head
pre
dict
ion
erro
r–
Impa
cts
on n
on-s
pin
rese
rve
requ
irem
ents
6/
Net
Loa
d M
odel
•Tw
o ye
ars
of d
ata
used
–M
ore
accu
racy
and
con
sist
ency
–Tw
o co
nsec
utiv
e ye
ars
need
ed la
ter i
n P
hase
2 fo
r tes
ting
A/S
m
etho
dolo
gy•
Ess
entia
l for
sys
tem
load
and
win
d ge
nera
tion
data
to b
e fo
r con
sist
ent
time
perio
d–
Com
mon
fact
ors
affe
ct b
oth
win
d an
d lo
ad•
Sys
tem
one
-min
ute
load
dat
a–
Bas
ed o
n 20
05 a
nd 2
006
ER
CO
T hi
stor
ical
reco
rdin
gs–
2006
dat
a sc
aled
up
to a
chie
ve a
vera
ge lo
ad (e
nerg
y) c
onsi
sten
t w
ith 2
008
ER
CO
T pr
edic
tions
–“S
tudy
Yea
r”–
2005
dat
a sc
aled
by
the
sam
e fa
ctor
–“P
revi
ous
Yea
r”–
Sca
le fa
ctor
= 1
.037
, com
pute
d fro
m th
e av
erag
e ra
tio o
f for
ecas
ted
2008
load
to 2
006
actu
al lo
ad a
cros
s al
l hou
rs
–D
ay-a
head
load
fore
cast
s pr
ovid
ed b
y E
RC
OT
7/
Win
d G
ener
atio
n M
odel
•W
ind
data
dev
elop
ed fo
r 200
5 an
d 20
06 b
y A
WS
Tru
ewin
d–
Hou
rly m
eso-
scal
e w
eath
er m
odel
–W
ind
gene
ratio
n ou
tput
def
ined
for m
ultip
le in
divi
dual
hyp
othe
tical
w
ind
plan
ts in
eac
h C
RE
Z–
Min
ute-
by-m
inut
e va
riatio
ns s
ynth
esiz
ed b
ased
on
ER
CO
T w
ind
data
for s
even
teen
exi
stin
g si
tes
(2 y
ears
of d
ata)
–W
ind
data
for o
ther
tim
e-fra
mes
(5-m
inut
e, 1
5-m
inut
e, 3
0-m
inut
e)
obta
ined
by
inte
grat
ing
1-m
inut
e da
ta•
CR
EZ
scen
ario
s de
velo
ped
–50
00 M
W, 1
5000
MW
and
two
1000
0 M
W s
cena
rios
–W
ind
capa
city
tota
ls p
er C
RE
Z pe
r ER
CO
T se
lect
ion
(nex
t slid
e)–
Win
d pl
ants
add
ed to
CR
EZ
portf
olio
in o
rder
of d
ecre
asin
g an
nual
ca
paci
ty fa
ctor
(mos
t pro
duct
ive
site
s us
ed fi
rst)
–P
lant
cap
acity
sca
led
up to
pro
duce
des
ired
outp
ut fo
r CR
EZ
•D
ay-a
head
win
d ge
nera
tion
pred
ictio
ns s
ynth
esiz
ed b
y A
WS
Tru
ewin
d
8/
CR
EZ
Sce
nario
s
W
ind
Dev
elop
men
t Sce
nario
C
REZ
Zon
e 50
00 M
W
10,0
00 M
W (1
) 10
,000
MW
(2)
15,0
00 M
W
none
12
0 12
0 12
0 12
0 2
60
1,56
0 1,
560
2,34
0 4
0 1,
500
0 0
5 35
5 1,
355
1,35
5 1,
355
6 40
0.5
400.
5 40
0.5
1,27
8.3
7 65
65
65
97
.5
9 81
4 1,
314
1,31
4 1,
971
10
2,46
4.5
2,96
4.5
2,96
4.5
4,44
6.8
12
400
400
400
600
14
160
160
160
240
15
60
60
60
90
19
101
101
101
211.
5 24
0
0 1,
500
2,25
0
Diff
eren
ce in
two
10,0
00 M
W s
cena
rios
is th
at th
e se
cond
has
1,5
00 M
W o
f win
d ge
nera
tion
in th
e G
ulf
coas
tal a
rea,
sub
stitu
ting
for a
like
am
ount
in th
e pa
nhan
dle
9/
1919
910
12
155
5
66
7
7
14
4
2
24
24 24
24
CR
EZ
Loca
tions
10/
Tim
e S
erie
s P
lots
and
D
aily
Pro
files
11/
In th
is n
ext s
et o
f slid
es, w
e w
ill sh
ow h
ow
win
d an
d lo
ad in
tera
ct to
cre
ate
the
net l
oad
curv
es.
Key
issu
es a
re:
•Im
pact
s on
net
load
pea
ks a
nd v
alle
ys•
Incr
ease
s in
ram
p ra
tes
•C
omm
on fa
ctor
s af
fect
ing
win
d an
d lo
ad
12/
Win
d an
d Lo
ad (1
5,00
0 M
W W
ind
Sce
nario
)(S
tudy
Yea
r Hou
rly D
ata)
Loa
d-15
,000
MW
Win
d - A
pril
Tim
e Se
ries
Plot
0
1000
0
2000
0
3000
0
4000
0
5000
0
6000
0
7000
0
1-Apr
8-Apr
15-Apr
22-Apr
29-Apr
Day
MW
-100
0
4000
9000
1400
0
1900
0
2400
0
2900
0
3400
0
Load
Win
d
Load MW
Wind MW
Both
win
d an
d lo
ad h
ave
varia
bilit
y(n
ote
that
the
win
d cu
rve
is o
n th
e rig
ht-h
and
scal
e an
d th
us it
s dy
nam
ic ra
nge
is a
mpl
ified
two
times
)
13/
Ave
rage
Apr
il D
aily
Loa
d an
d W
ind
Pro
file
(15,
000
MW
Win
d)20
08 L
oad-
15,0
00 M
W W
ind
- Apr
il Da
ily P
rofil
e
2000
0
2500
0
3000
0
3500
0
4000
0
4500
0
5000
0
5500
0
6000
0
6500
0
04
812
1620
24Ho
ur
MW
01000
2000
3000
4000
5000
6000
7000
8000
9000
Load
Win
d
(Stu
dy Y
ear H
ourly
Dat
a)
Load MW
Wind MW
•W
ind
is g
ener
ally
out
-of-p
hase
with
load
•Sh
arp
drop
in w
ind
in th
e m
orni
ng w
hen
load
is ri
sing
•Sh
arp
win
d in
crea
se w
hen
load
dro
ps s
harp
ly in
the
even
ing
14/
Dai
ly C
urve
Fro
m O
ne-M
inut
e D
ata
(S
tudy
Yea
r Hou
rly D
ata,
150
00 M
W S
cena
rio)
Typi
cal S
prin
g D
ay (A
pril
23)
0
5000
1000
0
1500
0
2000
0
2500
0
3000
0
3500
0
4000
0
4500
0
5000
0 0:00
2:00
4:00
6:00
8:00
10:0
012
:00
14:0
016
:00
18:0
020
:00
22:0
00:
00
Hour
of D
ay
Load, Wind, and Net Load (MW)Lo
adW
ind
Load
-Win
d
•C
urve
s ar
e qu
ite s
moo
th, w
ind
appe
ars
smoo
ther
•D
iver
sity
sm
ooth
es o
ut w
ind,
just
as
it do
es fo
r loa
ds
15/
Net
Loa
d (1
5,00
0 M
W W
ind
Sce
nario
) (S
tudy
Yea
r Hou
rly D
ata)
Loa
d-15
,000
MW
Win
d - A
pril
Tim
e Se
ries
Plot
0
1000
0
2000
0
3000
0
4000
0
5000
0
6000
0
7000
0
1-Apr
8-Apr
15-Apr
22-Apr
29-Apr
Day
MW
Win
dLo
adN
et L
oad
•Loa
d pe
aks
are
redu
ced,
som
e da
ys m
ore
than
oth
ers
•Val
leys
are
gre
atly
dee
pene
d
16/
Net
Loa
d C
ompa
rison
s –
One
Jan
uary
Wee
k (S
tudy
Yea
r Hou
rly D
ata)
0
5000
1000
0
1500
0
2000
0
2500
0
3000
0
3500
0
4000
0
4500
0
5000
0
15-Jan
16-Jan
17-Jan
18-Jan
19-Jan
20-Jan
21-Jan
22-Jan
Day
MW
Load
5,00
0 M
W10
,000
MW
(1)
10,0
00 M
W (2
)15
,000
MW
Incr
ease
d ra
mp
rate
Incr
ease
d da
ily ra
nge
•Cur
ve s
hape
is re
lativ
ely
sim
ilar f
or a
ll sc
enar
ios
•Pea
k-to
-val
ley
chan
ge in
crea
ses
with
win
d ge
nera
tion
•Res
ult i
s ra
mp
rate
s in
crea
sing
with
mor
e w
ind
17/
Net
Loa
d C
ompa
rison
s –
One
Apr
il W
eek
(Stu
dy Y
ear D
ata)
1000
0
1500
0
2000
0
2500
0
3000
0
3500
0
4000
0
4500
0
5000
0
5500
0
6000
0
13-Apr
14-Apr
15-Apr
16-Apr
17-Apr
18-Apr
19-Apr
20-Apr
Day
MW
Load
5,00
0 M
W10
,000
MW
(1)
10,0
00 M
W (2
)15
,000
MW
Thur
sday
Wed
nesd
ay
0
1000
0
2000
0
3000
0
4000
0
5000
0
MW
Load
Win
d (1
5 G
W S
cena
rio)
Net L
oad Lo
ad d
ip
Win
d sp
ike
•Pe
rturb
atio
n in
bot
h w
ind
and
load
at
the
sam
e tim
e, li
kely
from
co
mm
on s
ourc
e (e
.g.,
cold
fron
t)•
Valid
ana
lysi
s re
quire
s sy
nchr
oniz
ed lo
ad a
nd w
ind
data
18/
In s
umm
ary:
•B
oth
win
d an
d lo
ad a
re v
aria
ble
–D
aily
win
d ge
nera
tion
cycl
e is
gen
eral
ly o
ut-o
f-pha
se
with
load
–S
horte
r ter
m v
aria
tions
tend
to b
e le
ss c
orre
late
d
•C
omm
on fa
ctor
s af
fect
bot
h w
ind
and
load
–W
ind
impa
cts
cann
ot b
e co
rrec
tly c
onsi
dere
d in
depe
nden
tly o
f loa
d be
havi
or
19/
Tim
e of
Yea
r (S
easo
nal)
Ana
lysi
s
20/
In th
e ne
xt s
erie
s of
slid
es, t
ime
perio
ds w
ith c
ritic
al
oper
atin
g si
tuat
ions
are
iden
tifie
d an
d th
e im
pact
s of
w
ind
are
illus
trate
d by
tim
e se
ries
plot
s (a
ll w
ith th
e 15
000
MW
sce
nario
to m
ore
clea
rly d
emon
stra
te
win
d im
pact
s)C
ritic
al s
ituat
ions
incl
ude:
•
Max
imum
sys
tem
load
•M
inim
um n
et lo
ad•
Max
imum
net
load
•M
ost v
aria
ble
day
21/
Pro
files
of D
aily
Ave
rage
Loa
d an
d N
et L
oad
and
1-H
our D
elta
s(S
tudy
Yea
r Dat
a, 1
5000
MW
Sce
nario
)
-180
00
-120
00
-600
00
6000
1200
0
1800
0
2400
0
3000
0
3600
0
4200
0
4800
0
5400
0
Load and Net Load (MW)
-800
0
-500
0
-200
0
1000
4000
7000
1000
0
1300
0
1600
0
1900
0
2200
0
2500
0
2800
0
Max/Min of One-Hour Deltas (MW)
Load
Load
-Win
dM
ax L
oad-
Win
d 1H
r Del
tas
Min
Loa
d-W
ind
1Hr D
elta
s
Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Sep
Oct
Nov
Dec
Win
ter
Spr
ing
Sum
mer
Fall
Larg
est N
et-L
oad
Del
ta D
ay M
ay 8
th
Peak
Loa
d D
ay
Augu
st 1
7th
Min
Loa
d D
ay
Mar
27t
h
Thes
e ar
e th
e m
axim
um a
nd m
inim
um
delta
s (d
eriv
ativ
e of
hou
rly lo
ad c
urve
) for
ea
ch d
ay
Thes
e ar
e av
erag
e lo
ads
and
net l
oads
for
each
day
(equ
al to
dai
ly M
Wh/
24)
•Ba
sis
for s
elec
tion
of k
ey d
ates
for f
urth
er
illust
ratio
n an
d an
alys
is
22/
Larg
est N
et-L
oad
Del
ta D
ay -
Pro
files
and
Del
tas
(Stu
dy Y
ear D
ata,
150
00 M
W S
cena
rio)
Larg
est N
et-L
oad
Del
ta D
ay (M
ay 8
)
0
5000
1000
0
1500
0
2000
0
2500
0
3000
0
3500
0
4000
0
4500
0
5000
0
12
34
56
78
910
1112
1314
1516
1718
1920
2122
2324
Hour
of D
ay
Load and Net Load (MW)
-800
0
-600
0
-400
0
-200
0
02000
4000
6000
8000
1000
0
1200
0Lo
adLo
ad-W
ind
Win
d (1
5000
MW
)Lo
ad 1
Hr D
elta
sLo
ad-W
ind
1Hr D
elta
s
4-hr
pea
k sh
ift
~590
0 M
W ~630
0 M
W
~500
0 M
W
One-Hour Deltas (MW)
•W
ind
drop
in e
veni
ng b
efor
e lo
ad d
rop
caus
es a
late
pea
k in
net
load
, with
resu
lting
incr
ease
s in
ram
p ra
tes
23/
Mos
t Var
iabl
e* D
ay -
Pro
files
and
1-H
our D
elta
s(S
tudy
Yea
r Dat
a, 1
5000
MW
Sce
nario
)
Mos
t Var
iabl
e Ne
t Loa
d D
ay (J
uly
12)
0
7000
1400
0
2100
0
2800
0
3500
0
4200
0
4900
0
5600
0
6300
0
7000
0
12
34
56
78
910
1112
1314
1516
1718
1920
2122
2324
Hour
of D
ay
Load and Net Load (MW)
-800
0
-600
0
-400
0
-200
0
02000
4000
6000
8000
1000
0
1200
0
One-Hour Deltas (MW)
Load
Load
-Win
dW
ind
(150
00 M
W)
Load
1H
r Del
tas
Load
-Win
d 1H
r Del
tas
3435
0 M
W ri
se
over
12
hour
s (~
2900
MW
/Hr)
2756
0 M
W d
rop
over
8 h
ours
(~
3500
MW
/Hr)
* Lar
gest
net
-load
sig
ma
•An
ti-co
rrela
tion
of d
iurn
al lo
ad a
nd w
ind
curv
es
caus
e se
vere
mor
ning
and
eve
ning
ram
ps
24/
In s
umm
ary:
•W
ind
has
the
grea
test
impa
ct o
n ho
ur-to
-hou
r net
load
va
riatio
n in
the
late
spr
ing
and
sum
mer
–S
trong
coi
ncid
ence
of w
ind
drop
-off
with
mor
ning
load
pic
kup
–S
trong
coi
ncid
ence
of w
ind
pick
up w
ith e
veni
ng lo
ad
drop
-off
–La
rger
day
vs.
nig
ht n
et lo
ad s
win
g re
sults
in g
reat
er
ram
p ra
tes
•V
aria
tions
in th
e w
inte
r and
ear
ly s
prin
g m
ay b
e m
ore
oper
atio
nally
sig
nific
ant,
how
ever
, due
to lo
w n
et lo
ad le
vels
•N
et lo
ad p
eaks
can
be
shift
ed to
unu
sual
tim
es o
f day
by
win
d ch
ange
s w
ith h
igh
pene
tratio
n
25/
Net
-Loa
d V
aria
bilit
y fo
r V
ario
us T
imef
ram
es
26/
Sta
tistic
al a
naly
sis
of th
e lo
ad a
nd n
et lo
ad
varia
bilit
y is
sho
wn
in th
e ne
xt s
erie
s of
slid
es,
for d
iffer
ent t
imef
ram
esS
ome
expl
anat
ions
and
poi
nts
to c
onsi
der:
•D
elta
s ar
e th
e ch
ange
s in
ave
rage
net
load
fo
r suc
cess
ive
perio
ds –
(1, 5
, 15,
and
60
min
utes
con
side
red
in th
is s
tudy
)•
Ave
rage
del
tas
over
a d
ay o
r lon
ger p
erio
d ar
e in
here
ntly
nea
r zer
o, s
o th
e st
anda
rd
devi
atio
n of
the
delta
s ar
e us
ed a
s a
mea
sure
of v
aria
bilit
y•
Del
tas
incl
ude
both
the
effe
cts
of lo
nger
-cy
cle
ram
ping
as
wel
l as
rand
om “j
itter
”
27/
One
-Min
ute
Load
-Win
d V
aria
bilit
y
(
Stu
dy Y
ear D
ata,
150
00 M
W S
cena
rio)
-39.
2 / 3
8.1
-33.
6 / 3
3.0
Mea
n(-
/+ D
elta
s)
491.
6
-513
.7
43.2
2
Load
-alo
ne
(MW
)
-552
.6M
in. D
elta
Max
. Del
ta
Sigm
a (D
elta
)
538.
3
49.6
7
With
Win
d (M
W)
Sta
tistic
al S
umm
ary
0
1000
0
2000
0
3000
0
4000
0
5000
0
6000
0
7000
0
8000
0
9000
0
< -240
-240 – -224
-224 – -208
-208 – -192
-192 – -176
-176 – -160
-160 – -144
-144 – -128
-128 – -112
-112 – -96
-96 – -80
-80 – -64
-64 – -48
-48 – -32
-32 – -16
-16 – 0
0 – 16
16 – 32
32 – 48
48 – 64
64 – 80
80 – 96
96 – 112
112 – 128
128 – 144
144 – 160
160 – 176
176 – 192
192 – 208
208 – 224
224 – 240
> 240
MW
Number of One-Minute Periods
Load
- W
ind
Load
Gre
ates
t diff
eren
ce
betw
een
net l
oad
and
load
alo
ne is
in
the
dow
nwar
d ch
ange
dire
ctio
n
111
/ 139
79 /
8710
5 / 1
29>µ
±6σ
(−
/+)
3593
/ 27
6915
17 /
1239
1711
/ 14
35>µ
±3σ
(−
/+)
571
/ 551
247
/ 297
338
/ 391
>µ±
4σ
(−/+
)
9277
/ 74
0846
04 /
3547
4696
/ 38
05>µ
±2.
5σ
(−/+
)
1.61
%
147
/ 203
Load
-alo
ne
(Del
ta-M
W)
σ =
43.2
2
3.17
%1.
55%
% >
2.5
σ
>µ±
5σ
(−/+
)17
5 / 2
2511
7 / 1
59
With
Win
d(D
elta
-MW
)U
sing
loa
d σ
With
Win
d (D
elta
-MW
)σ
= 49
.67
Ext
rem
e 1-
Min
ute
Del
tas
1-m
inut
e st
anda
rd d
evia
tion
(σ) i
ncre
ases
by
14.9
%M
axim
um 1
-min
ute
rise
incr
ease
s by
46.
4 M
WM
axim
um 1
-min
ute
drop
incr
ease
s by
38.
9 M
WN
umbe
r of 1
-min
ute
delta
s gr
eate
r tha
n 2.
5 (lo
ad)σ
incr
ease
s 96
%
28/
Hou
rly L
oad-
Win
d V
aria
bilit
y(S
tudy
Yea
r Dat
a, 1
5000
MW
Sce
nario
)
0
200
400
600
800
1000
1200
< -7000-7000 – -6500-6500 – -6000-6000 – -5500-5500 – -5000-5000 – -4500-4500 – -4000-4000 – -3500-3500 – -3000-3000 – -2500-2500 – -2000-2000 – -1500-1500 – -1000-1000 – -500-500 – 00 – 500500 – 10001000 – 15001500 – 20002000 – 25002500 – 30003000 – 35003500 – 40004000 – 45004500 – 50005000 – 55005500 – 60006000 – 65006500 – 7000> 7000
MW
No. 1-Hour Periods
Load
- W
indLo
ad
Agai
n, th
e do
wnw
ard
varia
tions
are
m
ost c
hang
ed-1
741
/ 167
7-1
366
/ 142
5M
ean
(-/+
Del
tas)
5203
-483
8
1758
Load
-alo
ne
(MW
)
-750
7M
in. D
elta
Max
. Del
ta
Sig
ma
(Del
ta)
6861
2159
With
Win
d (M
W) 78
/ 36
6 / 5
0 / 0
>µ±
3σ
(−/+
)
224
/ 161
6 / 2
643
/ 26
> µ±
2.5σ
(−
/+)
0.79
%
0 / 0
Load
-alo
ne
(Del
ta-M
W)
σ =
1758
4.39
%0.
37%
% >
2.5
σ
> µ±
4σ
(−/+
)1
/ 00
/ 0
With
Win
d(D
elta
-MW
)U
sing
loa
d σ
With
Win
d (D
elta
-MW
)σ
= 21
59
Ext
rem
e 1-
Hou
r Del
tas
1-hr
sta
ndar
d de
viat
ion
(σ) i
ncre
ases
by
22.8
%
Max
imum
1-h
our r
ise
incr
ease
s by
165
8 M
WM
axim
um 1
-hou
r dro
p in
crea
ses
by 2
669
MW
Num
ber o
f 1-h
r del
tas
grea
ter t
han
2.5
(load
) σin
crea
ses
458%
29/
Var
iabi
lity
as a
Fun
ctio
n of
Win
d P
enet
ratio
n
10100
1000
1000
0
050
0010
000
1500
0
Win
d G
ener
atio
n (M
W)
Sigma (MW)
15
1560
Del
ta T
imef
ram
e
•Var
iabi
lity
incr
ease
s w
ith w
ind
pene
tratio
n.
•Inc
reas
e is
ver
y sl
ight
on
this
sca
le
30/
Nor
mal
ized
Var
iabi
lity
as a
Fun
ctio
n of
Win
d P
enet
ratio
n
10152025303540455055
050
0010
000
1500
0
Win
d G
ener
atio
n (M
W)
Normalized Sigma (MW/min)1
515
60
Del
ta T
imef
ram
e
•Sig
mas
nor
mal
ized
in te
rms
of M
W/m
in (e
.g.,
σ 5/ 5
)•I
ncre
ase
is li
near
, but
with
a s
hallo
w s
lope
31/
Nor
mal
ized
Sig
ma
as a
Fun
ctio
n of
Tim
espa
n
0102030405060
110
100
Tim
espa
n (m
inut
es)
Normalized Sigma (MW/min)
Load
Onl
y5,
000
MW
10,0
00 M
W10
,000
MW
15,0
00 M
W
`
•Th
ere
is a
bas
elin
e of
var
iabi
lity
that
is a
fu
nctio
n of
the
long
er-te
rm lo
ad c
ycle
. •
An in
crem
enta
l am
ount
of v
aria
tion
appe
ars
at th
e sh
orte
st ti
mef
ram
es (1
& 5
min
.)
32/
Incr
ease
in V
aria
bilit
y R
elat
ive
to T
ime
Spa
n
For a
ll w
ind
scen
ario
s, th
e re
lativ
e in
crea
se in
va
riabi
lity
(sig
ma)
, rel
ativ
e to
sig
ma
of lo
ad
alon
e, b
ecom
es m
ore
sign
ifica
nt fo
r lon
ger
time
win
dow
s
0%5%10%
15%
20%
25%
110
100
Tim
espa
n (m
inut
es)
% Increase in Variability
5,00
0 M
W
10,0
00 M
W
10,0
00 M
W
15,0
00 M
W
33/
In s
umm
ary:
•V
aria
tions
ove
rtim
espa
nsof
10+
min
utes
are
prim
arily
due
to
load
cyc
le•
Sho
rtert
imes
pans
have
an
incr
emen
tal c
ompo
nent
due
to
rand
om “n
oise
” var
iatio
ns•
Win
d ca
uses
a s
light
, lin
ear i
ncre
ase
in p
erio
d-to
-per
iod
varia
bilit
y ov
er a
ll tim
espa
ns•
Impa
ct is
som
ewha
t mor
e si
gnifi
cant
for l
onge
r tim
espa
ns–
I.e.,
win
d ad
ds to
var
iabi
lity
prim
arily
due
to c
reat
ing
larg
er d
aily
net
load
sw
ings
–A
dditi
on to
the
rand
om “n
oise
” is
less
sig
nific
ant
•S
mal
l diff
eren
ces
in s
tatis
tical
met
rics
betw
een
“stu
dy y
ear”
(b
ased
on
2006
) and
“pre
viou
s ye
ar” (
base
d on
200
5)
indi
cate
sta
bilit
y of
resu
lts
34/
Var
iabi
lity
at D
iffer
ent
Load
Lev
els
35/
The
abili
ty o
f the
sys
tem
to a
ccom
mod
ate
net
load
var
iatio
ns is
gre
atly
a fu
nctio
n of
the
abso
lute
net
load
leve
l.
Sys
tem
man
euve
rabi
lity
tend
s to
incr
ease
with
th
e ge
nera
tion
leve
l bec
ause
:•
Var
iatio
ns o
f a g
iven
mag
nitu
de a
re la
rger
in
prop
ortio
n to
the
com
mitt
ed g
ener
ator
s•
Uni
ts lo
wer
on
the
disp
atch
sta
ck te
nd to
be
base
load
uni
ts th
at a
re le
ss m
aneu
vera
ble
The
follo
win
g sl
ides
cor
rela
te v
aria
bilit
y w
ith
load
leve
l
36/
Win
d D
urat
ion
and
Pen
etra
tion
(150
00 M
W)
(Stu
dy Y
ear D
ata)
0
2500
5000
7500
1000
0
1250
0
1500
0
087
617
5226
2835
0443
8052
5661
3270
0878
8487
60
Hour
s of
Yea
r
Total Wind Output(MW)
0%10%
20%
30%
40%
50%
60%
Wind Penetration (%)
Tota
l Win
d (M
W)
Pen
etra
tion
(%)
Not
e: D
ata
for t
hese
cur
ves
wer
e in
depe
nden
tly s
orte
d
Win
d ge
nera
tion
is a
bove
75
% o
f ins
talle
d ca
paci
ty
only
10%
of t
he y
ear
Med
ian
inst
anta
neou
s pe
netr
atio
n is
onl
y 16
%,
com
pare
d to
23%
on
a ca
paci
ty b
asis
Win
d Sc
enar
ioM
ax In
stan
tane
ous
Pene
trat
ion
5000
21%
1000
0 (1
)39
%10
000
(2)
39%
1500
057
%
37/
Load
and
Net
Loa
d V
aria
bilit
y by
Loa
d Le
vel
(
Stu
dy Y
ear H
ourly
Dat
a, 1
5000
MW
Sce
nario
)(A
vera
ge +
/-x*
sigm
a, M
inim
um, M
axim
um)
Load
Load
-Win
d
-800
0
-600
0
-400
0
-200
00
2000
4000
6000
8000
MW
12
34
56
78
910
Load
Dec
ile
Mea
n +
Sigm
a
Mea
n -2
.5*S
igm
a
Mea
n -S
igm
a
Mea
n +
2.5*
Sigm
aM
ax Min
Very
littl
e im
pact
on
varia
bilit
y at
ver
y hi
gh lo
ad le
vels
•Va
riabi
lity
is c
hang
ed li
ttle
at lo
wer
load
s•
Sam
e va
riabi
lity,
but
with
few
er d
ispa
tcha
ble
gene
rato
rs
38/
Net
Loa
d D
urat
ion
Cur
ves
for V
ario
us W
ind
Sce
nario
s(S
tudy
Yea
r Dat
a)
0
1000
0
2000
0
3000
0
4000
0
5000
0
6000
0
7000
0
087
617
5226
2835
0443
8052
5661
3270
0878
8487
60
Hou
rs o
f Yea
r
Net Load (MW)
Load
-Alo
neLo
ad-5
000
MW
Load
-100
00 M
W(1
)Lo
ad-1
0000
MW
(2)
Load
-150
00 M
WM
in L
oad
(224
26 M
W)
Low
net
load
per
iods
Min
Loa
d 22
426
MW
Not
e: D
ata
for t
hese
cur
ves
wer
e in
depe
nden
tly s
orte
d
Not
e: D
ata
for t
hese
cur
ves
wer
e in
depe
nden
tly s
orte
d
•N
et lo
ads
belo
w c
urre
nt m
inim
um lo
ad m
ay b
e a
real
op
erat
iona
l cha
lleng
e•
Ave
rage
win
d ou
tput
is d
oubl
e du
ring
low
net
-load
hou
rs
39/
Net
Loa
d D
urat
ion
Cur
ves
for L
ow L
oad
Per
iods
(Stu
dy Y
ear D
ata)
8000
1200
0
1600
0
2000
0
2400
0
2800
0
3200
0 6700
6900
7100
7300
7500
7700
7900
8100
8300
8500
8700
Hou
rs o
f Yea
r
Net Load (MW)
Load
-Alo
neLo
ad-5
000
MW
Load
-100
00 M
W(1
)Lo
ad-1
0000
MW
(2)
Load
-150
00 M
WM
in L
oad
(224
26 M
W)
1945
hrs
(35.
7% o
f Win
d En
ergy
)
1141
hrs
(21.
4%E)
470
hrs
(9.7
%E)
1209
hrs
(23.
3%E)
8760
Win
d en
ergy
lost
if w
ind
is
curta
iled
to h
old
min
net
load
sa
me
(5,0
00 M
W s
cena
rio)
•Th
ere
are
inhe
rent
trad
eoffs
bet
wee
n co
sts
of g
ener
atio
n fle
xibi
lity
and
ener
gy lo
st to
cur
tailm
ent
Cur
tailm
ent t
o ho
ld
curr
ent m
inim
um fo
r 15
GW
of w
ind
resu
lts in
ex
cess
ive
ener
gy lo
ss
40/
In s
umm
ary:
•In
gen
eral
, var
iabi
lity
is re
lativ
ely
cons
tant
ove
r the
rang
e of
load
leve
ls•
Win
d co
ntrib
utio
n to
var
iabi
lity
is a
lso
rela
tivel
y co
nsta
nt•
Net
load
s ca
n be
driv
en to
low
leve
ls w
ith la
rge
win
d ca
paci
ty–
Inst
anta
neou
s pe
netra
tion
reac
hes
55%
with
15,
000
MW
of
win
d an
d 20
08 lo
ad le
vels
•It
is n
ot fe
asib
le to
mai
ntai
n th
e sa
me
min
imum
load
leve
ls
Abilit
y of
the
ERC
OT
syst
em to
mee
t ram
ping
requ
irem
ents
w
ill be
spe
cific
ally
stu
died
in P
hase
2
41/
Tim
e of
Day
Var
iabi
lity
Ana
lysi
s
42/
The
next
slid
es e
xam
ine
how
load
va
riabi
lity
varie
s ov
er th
e ho
urs
of th
e da
y fo
r diff
eren
t sea
sons
43/
Apr
il, H
ourly
Loa
d an
d N
et L
oad
Del
tas
(S
tudy
Yea
r Dat
a, 1
5000
MW
Sce
nario
)
(Avg
. +/-
sigm
a, M
inim
um, M
axim
um)
01
23
45
67
89
1011
1213
1415
1617
1819
2021
2223
2425
06000
1200
0
1800
0
2400
0
3000
0
3600
0
4200
0
4800
0
-800
0
-600
0
-400
0
-200
00
2000
4000
6000
8000
-800
0
-600
0
-400
0
-200
00
2000
4000
6000
8000
Hou
r of D
ay
Load and Net Load Delta (MW)
Total Load (MW)
Win
d is
a la
rge
cont
ribut
or to
ra
mpi
ng re
quire
men
ts d
urin
g m
orni
ng lo
ad ri
se a
nd e
veni
ng lo
ad
drop
off
in th
e sp
ring
5900
MW
/hr d
rop
5700
MW
/hr r
ise
Load
Del
tas
Load
-Win
d D
elta
sTo
tal L
oad
Load
-Win
d
44/
July
, Hou
rly L
oad
and
Net
Loa
d D
elta
s(S
tudy
Yea
r Dat
a, 1
5000
MW
Sce
nario
)
(Avg
. +/-
sigm
a, M
inim
um, M
axim
um)
01
23
45
67
89
1011
1213
1415
1617
1819
2021
2223
2425
07500
1500
0
2250
0
3000
0
3750
0
4500
0
5250
0
6000
0
-800
0
-600
0
-400
0
-200
00
2000
4000
6000
8000
-800
0
-600
0
-400
0
-200
00
2000
4000
6000
8000
Hou
r of D
ay
Load and Net Load Delta (MW)
Load and Net Load (MW)
In s
umm
er, w
ind
mak
es th
e la
rges
t im
pact
dur
ing
the
early
m
orni
ng lo
ad ri
se a
nd e
veni
ng
load
dro
p of
f
6650
MW
/hr r
ise
6400
MW
/hr d
rop Lo
ad D
elta
sLo
ad-W
ind
Del
tas
Tota
l Loa
dLo
ad-W
ind
45/
Sum
mer
Mor
ning
Loa
d R
ise
Per
iod
June
–S
epte
mbe
r7
–11
AM
46/
Sum
mer
Mor
ning
Loa
d R
ise
Var
iabi
lity
–15
,000
MW
(Stu
dy Y
ear D
ata)
3237
2797
Mea
n (D
elta
)
250
9M
in. D
elta
Max
. Del
ta
Sig
ma
(Del
ta)
6528
4160
1122
732
with
Win
d (M
W)
Load
-alo
ne
(MW
)
2008
Loa
d-15
,000
MW
Win
d - S
umm
er M
orni
ng L
oad
Ris
e (J
un-S
ep, 7
-11
AM)
010203040506070
< 200
200 – 400
400 – 600
600 – 800
800 – 1000
1000 – 1200
1200 – 1400
1400 – 1600
1600 – 1800
1800 – 2000
2000 – 2200
2200 – 2400
2400 – 2600
2600 – 2800
2800 – 3000
3000 – 3200
3200 – 3400
3400 – 3600
3600 – 3800
3800 – 4000
4000 – 4200
4200 – 4400
4400 – 4600
4600 – 4800
4800 – 5000
5000 – 5200
5200 – 5400
5400 – 5600
5600 – 5800
> 5800
MW
No. of 1 hr periods
Load
- W
ind
Load
Mea
n 1-
hour
del
ta in
crea
ses
by 1
5.7%
due
to w
ind
Sig
ma
incr
ease
s by
53.
3%
Num
ber o
f 1-h
our r
ises
gre
ater
th
an 4
000
MW
incr
ease
s fro
m
9 to
123
291
0>
µ+2
.5σ
00
Load
-alo
ne
(Del
ta-M
W)
σ =
732
10
> µ
+ 4σ
> µ
+3σ
150
With
Win
d(D
elta
-MW
)U
sing
loa
d σ
With
Win
d (D
elta
-MW
)σ
= 11
22
Ext
rem
e 1-
Hou
r Ris
es
47/
Sum
mer
Mor
ning
Loa
d R
ise
Var
iabi
lity
(Stu
dy Y
ear D
ata)
Sum
mer
Mor
ning
Loa
d R
ise
0
1000
2000
3000
4000
5000
6000
7000
050
0010
000
1500
020
000
Win
d Pe
netra
tion
(MW
)
MW
µ σ µ +
2.5
σE
xtre
me
•Ex
trem
a in
crea
se m
ore
quic
kly
with
add
ition
al w
ind
gene
ratio
n th
an m
ean
+ 2.
5 s.
d.•
Dis
tribu
tion
is le
ss c
hara
cter
ized
by
a no
rmal
dis
tribu
tion;
m
ore
outli
ers
48/
Win
ter A
ftern
oon
Load
Ris
e P
erio
dN
ovem
ber –
Febr
uary
4 –
6 P
M
49/
Win
ter A
ftern
oon
Load
Ris
e V
aria
bilit
y(S
tudy
Yea
r Dat
a)
1573
1517
Mea
n (D
elta
)
-276
8-8
86M
in. D
elta
Max
. Del
ta
Sig
ma
(Del
ta)
6861
3678
1556
866
with
Win
d (M
W)
Load
-alo
ne
(MW
)
2008
Loa
d-15
,000
MW
Win
d - W
inte
r Afte
rnoo
n Lo
ad R
ise
(Nov
-Feb
, 4-6
PM)
05101520253035
< -2800-2800 – -2700-2700 – -2400-2400 – -2100-2100 – -1800
-1800 – -1500-1500 – -1200-1200 – -900-900 – -600
-600 – -300-300 – 00 – 300300 – 600600 – 900
900 – 12001200 – 15001500 – 18001800 – 2100
2100 – 24002400 – 27002700 – 30003000 – 33003300 – 3600
3600 – 39003900 – 42004200 – 45004500 – 4800
4800 – 51005100 – 54005400 – 57005700 – 6000> 6000
MW
No. of 1 hr periods
Load
- W
ind
Load
Mor
e ou
tlier
s,
both
dire
ctio
nsM
ean
1-ho
ur d
elta
incr
ease
s by
3.
7% d
ue to
win
d
Sig
ma
incr
ease
s by
79.
7%
Num
ber o
f 1-h
our r
ises
gre
ater
th
an 3
000
MW
incr
ease
s fro
m
11 to
36
225
0>
µ+2
.5σ
00
Load
-alo
ne
(Del
ta-M
W)
σ =
866
70
> µ
+ 4σ
> µ
+3σ
144
With
Win
d(D
elta
-MW
)U
sing
loa
d σ
With
Win
d (D
elta
-MW
)σ
= 15
50
Ext
rem
e 1-
Hou
r Ris
es
50/
•W
ind
varia
bilit
y in
crea
ses
linea
rly w
ith p
enet
ratio
n–
1-ho
ur s
igm
a in
crea
ses
by 2
3% w
ith 1
5,00
0 M
W o
f win
d–
Gre
ater
var
iabi
lity
and
extre
me
ram
ps o
bser
ved
durin
g ce
rtain
mor
ning
, afte
rnoo
n an
d ev
enin
g pe
riods
–G
reat
er n
et lo
ad v
aria
bilit
y in
the
sprin
g an
d su
mm
er•
The
mor
e si
gnifi
cant
impa
ct is
that
min
imum
net
lo
ads
are
grea
tly re
duce
d–
Gre
ater
rela
tive
varia
bilit
y at
ligh
t loa
d–
Less
sys
tem
resp
onsi
vene
ss•
Win
d im
pact
on
varia
bilit
y is
prim
arily
due
to m
ulti-
hour
cyc
les,
incr
emen
t due
to “n
oise
” is
smal
l•
Win
d ha
s in
crem
enta
l im
pact
on
aver
age
and
extre
me
erro
rs, e
spec
ially
dur
ing
early
mor
ning
s an
d af
tern
oons
in w
inte
r & s
prin
g–
On
aver
age,
net
load
is n
early
as
pred
icta
ble
as lo
ad a
lone
Var
iabi
lity
Ana
lysi
s S
umm
ary
51/
Ext
rem
e W
eath
er
Con
ditio
ns
Impa
ct o
n A
ncill
ary
Ser
vice
s
52/
Impa
ct o
f Ext
rem
e W
eath
er C
ondi
tions
•E
RC
OT’
scu
rren
t “ex
trem
e” w
eath
er c
ondi
tions
are
la
rgel
y de
fined
by
tem
pera
ture
…
–R
egul
atio
n re
serv
es m
ay b
e in
crea
sed
by a
fa
ctor
of t
wo
–R
espo
nsiv
e re
serv
es a
nd n
on-s
pinn
ing
rese
rves
m
ay b
e pr
ocur
ed•
With
larg
e am
ount
s of
win
d, o
ther
wea
ther
co
nditi
ons
may
cre
ate
abno
rmal
net
load
dev
iatio
ns–
Inve
stig
ate
mos
t sev
ere
even
ts in
win
d an
d N
et-
Load
–D
evel
op m
odifi
ed p
roce
dure
s or
requ
irem
ents
for
iden
tifyi
ng a
nd re
spon
ding
to th
e an
cilla
ry s
ervi
ce
need
s dr
iven
by
extre
me
wea
ther
.
53/
Impa
ct o
n R
espo
nsiv
e R
eser
ve S
ervi
ces
(RR
S)
(Spi
nnin
g R
eser
ves)
•U
sed
to re
stor
e E
RC
OT
syst
em fr
eque
ncy
with
in th
e fir
st fe
w m
inut
es o
f an
even
t …
•S
et a
t 230
0 M
W fo
r nor
mal
con
ditio
ns–
base
d on
sim
ulta
neou
s lo
ss o
f lar
gest
two
gene
ratio
n un
its•
May
be
incr
ease
d un
der “
extre
me
cond
ition
s”•
Non
-spi
nnin
g re
serv
es (N
SR
S) m
ay b
e de
ploy
ed
whe
n “la
rge”
am
ount
s of
spi
n ar
e no
t ava
ilabl
e–
NS
RS
can
be
ram
ped
to o
utpu
t lev
el w
ithin
30-
min
utes
Ext
rem
e dr
ops
in w
ind
prod
uctio
n w
ithin
30
min
sar
e in
vest
igat
ed to
det
erm
ine
impa
ct o
n R
RS
54/
In th
is n
ext s
et o
f slid
es, w
e w
ill sh
ow:
•A
WS
T an
alys
is o
f ram
p ev
ents
in e
xist
ing
win
d–
Cau
ses,
freq
uenc
y an
d pr
edic
tabi
lity
–Im
plic
atio
ns fo
r win
d sc
enar
ios
•P
roba
bilit
y of
“lar
ge” w
ind
trans
ition
s/ra
mp
even
ts•
Impa
ct o
f div
ersi
ty o
n w
ind
ram
p ev
ents
•D
istri
butio
n, ti
min
g an
d m
agni
tude
of e
vent
s•
Impl
icat
ions
for R
RS
requ
irem
ents
55/
Ana
lysi
s of
Wes
t Tex
as W
ind
Pla
nt R
amp
Eve
nts
To id
entif
y an
d cl
assi
fy e
vent
s, A
WS
True
win
d:•
Exa
min
ed tw
o ye
ars
of o
ne-m
inut
e pl
ant o
utpu
t dat
a pr
ovid
ed b
y E
RC
OT
–Id
entif
ied
30-m
inut
e pe
riods
with
agg
rega
te w
ind
gene
ratio
n ch
ange
s >
200
MW
Tota
l 976
MW
rate
d ca
paci
ty fo
r pla
nts
in a
naly
sis
Obv
ious
cas
es o
f non
-wea
ther
cur
tailm
ents
and
shu
tdow
ns
excl
uded
–E
xam
ined
ava
ilabl
e m
eteo
rolo
gica
l rec
ords
for t
he p
erio
ds
–C
ateg
oriz
ed th
e ev
ents
by
met
eoro
logi
cal c
ause
s•
Ana
lyze
d si
gnifi
cant
200
5-20
06 w
eath
er e
vent
s id
entif
ied
by
ER
CO
T, d
eter
min
ed th
ose
wer
e as
soci
ated
with
larg
e ch
ange
s in
w
ind
gene
ratio
n•
Ana
lyze
d th
e ev
ent o
f 24
Febr
uary
200
7 an
d es
tabl
ishe
d th
e ca
use
for t
he d
ecre
ase
in e
nerg
y pr
oduc
tion.
From
the
resu
lts, A
WS
True
win
des
timat
ed th
e m
axim
um
likel
y ch
ange
in a
30-
min
ute
perio
d fo
r the
15,
000
MW
sc
enar
io
56/
Met
eoro
logi
cal C
ause
s of
Win
d R
amp-
Up
Eve
nts
•Fr
onta
l sys
tem
/trou
gh/d
ry li
ne
–D
ensi
ty fr
onts
or a
ir m
ass
disc
ontin
uitie
s –
Acc
ompa
nyin
g fa
ll/ris
e pr
essu
re c
oupl
et, r
esul
ts in
rapi
d w
ind-
spee
d ch
ange
, –
Mos
tly m
ove
wes
t to
east
or n
orth
wes
t to
sout
heas
t –
Up
to 1
000
km lo
ng a
nd 1
00-2
00 k
m w
ide
–P
ropa
gate
at o
ver 1
5 m
/s (3
4 m
ph)
•C
onve
ctio
n-in
duce
d ou
tflow
or g
ust f
ront
s –
Occ
ur o
n th
em
esos
cale
(tens
to h
undr
eds
of s
quar
e km
) –
Usu
ally
pro
paga
tera
dial
lyou
twar
d fro
m th
unde
rsto
rm c
lust
ers
–P
ropo
gatio
n sp
eeds
in e
xces
s of
25
m/s
•Lo
w-le
vel j
et (L
LJ)
–O
ccur
regu
larly
yea
r-ro
und
in th
e S
outh
ern
Gre
at P
lain
s–
Two
type
s:1)
Noc
turn
al L
LJ –
max
imum
at 5
AM
2)P
re-fr
onta
l LLJ
–ah
ead
of c
old
front
57/
Met
eoro
logi
cal C
ause
s of
Win
d R
amp-
Dow
n E
vent
s
•S
lack
enin
g of
a p
ress
ure
grad
ient
•
Pas
sage
of a
loca
l pre
ssur
e co
uple
t •
Eac
h ca
n oc
cur f
or s
ame
even
ts c
ausi
ng ra
mp-
up•
Hig
h w
ind
spee
ds th
at e
xcee
d w
ind
turb
ine
cut-o
ut
–Th
resh
old
(22-
25 m
/s)
–R
espo
nsib
le fo
r Feb
ruar
y 24
, 200
7 ev
ent
58/
Eve
nt P
ropa
gatio
n E
xam
ple
(Aug
ust 1
1, 2
006)
•LE
FT: N
EX
RA
D (r
adar
) im
age
from
Mid
land
TX
(KM
AF)
for 1
801
LT o
n 11
Aug
ust
2006
-R
ed a
rrow
s sh
ow o
utflo
w fr
om th
unde
rsto
rm c
ompl
ex to
the
wes
t•
RIG
HT:
Out
flow
bou
ndar
y an
hou
r lat
er (1
901
LT) n
ow a
ppro
achi
ng c
lust
er o
f win
d pl
ants
sou
th a
nd n
orth
east
of K
MA
F•
Sho
rtly
afte
r, ra
mp
even
t of +
600
MW
was
obs
erve
d w
ithin
a 3
0 m
inut
e pe
riod
•Lo
wer
arr
ows
indi
cate
bou
ndar
y tra
vers
ed a
bout
100
km
(62
mile
s)in
an
hour
59/
Ext
rem
e W
ind
Eve
nts*
in E
xist
ing
Dat
a (2
006)
**
* 200
MW
exc
ursi
on
with
in 3
0 m
inut
es
** B
ased
on
appr
oxim
atel
y 97
6 M
W
of in
stal
led
capa
city
60/
Sum
mar
y of
Ram
p E
vent
s fo
r Exi
stin
g W
ind
Dat
a (2
005/
2006
)
•59
ram
p ev
ents
iden
tifie
d (6
0% u
p, 4
0% d
own)
•La
rges
t ram
p-up
eve
nt o
n 9
July
200
5–
near
ly 4
00 M
W in
crea
se (o
ver 3
00%
from
200
MW
)
•La
rges
t ram
p-do
wn
even
t on
12 M
ay 2
005
–33
1 M
W d
ecre
ase,
(mor
e th
an 5
8% fr
om 5
71 M
W)
•P
rimar
y ca
uses
: (1)
con
vect
ive
(2) f
ront
al
pass
ages
(3) w
eake
ning
pre
ssur
e gr
adie
nts
•D
istin
ct d
iurn
al in
crea
se in
the
frequ
ency
of r
amp-
up e
vent
s du
ring
the
even
ing
hour
s, p
artic
ular
ly
arou
nd 5
PM
loca
l tim
e, d
ue to
con
vect
ion,
es
peci
ally
stro
ng to
sev
ere
thun
ders
torm
s•
Sea
sona
l inc
reas
e in
freq
uenc
y of
ram
p-up
eve
nts
from
late
win
ter t
hrou
gh s
umm
er, w
hile
ram
p-do
wn
even
ts s
how
no
clea
r pat
tern
.
61/
Ram
p E
vent
Cas
e S
tudy
(Dec
embe
r 28,
200
6)
•W
eak
grad
ient
ahe
ad o
f col
d fr
ont
–A
n ar
ea o
f wea
k pr
essu
re g
radi
ent m
oves
ea
stw
ard
acro
ss w
est-c
entra
l Tex
as
betw
een
14:0
0 an
d 15
:00
LST
–S
ince
win
d sp
eed
is p
ropo
rtion
al to
the
pres
sure
gra
dien
t, th
ere
is a
sig
nific
ant
redu
ctio
n in
win
d po
wer
out
put a
nd w
ind
spee
d as
this
feat
ure
pass
es–
The
drop
in w
ind
spee
d is
mos
t not
able
at
Fort
Sto
ckto
n (K
FST)
, Lub
bock
(KLB
B) a
nd
Ode
ssa
(KO
DO
)–
Ther
e is
a s
econ
dary
dro
p in
pow
er o
utpu
t ar
ound
16:
00 L
ST
as w
inds
con
tinue
to
dim
inis
h (to
bel
ow th
e cu
t-in
valu
e of
4 m
/s
at th
e st
atio
ns)
•Fr
onta
l pas
sage
–Fo
llow
ing
the
wea
k pr
essu
re fi
eld,
a
stro
nger
gra
dien
t mov
es in
to th
e ar
ea a
fter
the
front
al p
assa
ge (a
ppro
xim
atel
y 15
:00
–16
:00
LST)
–
Win
d sp
eeds
and
out
put i
ncre
ase
rapi
dly
by 1
8:00
–
Pla
nt o
utpu
t, w
hich
had
dec
reas
ed to
abo
ut
100
MW
(or 1
0% o
f the
rate
d ca
paci
ty),
then
rapi
dly
rose
as
win
d sp
eeds
rose
ab
ove
the
cut-i
n va
lue .
62/
Ram
p E
vent
Cas
e S
tudy
(Feb
ruar
y 24
, 200
7)•
Stro
ng u
pper
-leve
l sto
rm s
yste
m p
asse
d ov
er
north
ern
New
Mex
ico
and
the
panh
andl
e of
Tex
as
subs
tant
ially
tigh
teni
ng th
e pr
essu
re g
radi
ents
ove
r w
est T
exas
, res
ultin
g in
stro
ng to
sev
ere
win
ds
alon
g a
stra
ight
line
acr
oss
muc
h of
the
area
–8
AM -
high
win
d sp
eeds
see
n by
mos
t win
d pr
ojec
ts,
max
imum
win
d gu
st re
porte
d w
as 9
4 m
ph
–9
AM
-ag
greg
ate
outp
ut in
crea
sed
from
just
ove
r 11
00 M
W to
nea
rly 2
000
MW
(rat
ed c
apac
ity)
–10
AM
-su
stai
ned
win
ds e
xcee
ded
25 m
/s (5
5 m
ph)
outp
ut a
t mos
t win
d fa
rms,
out
put d
eclin
ed a
s tu
rbin
e-cu
toff
thre
shol
d re
ache
d–
11 A
M -
mos
t int
ense
pre
ssur
e gr
adie
nts
and
win
ds
mov
ed e
astw
ard,
win
d sp
eeds
rela
xed,
turb
ines
re
sum
ed p
ower
pro
duct
ion,
resu
lting
in a
gra
dual
in
crea
se in
tota
l out
put t
o pr
e-ev
ent l
evel
s
•To
tal d
rop
in p
lant
out
put w
as m
ore
than
150
0 M
W
over
a 9
0 m
inut
e pe
riod
•M
ost r
apid
dec
lines
occ
urre
d at
the
Hor
se H
ollo
w
inte
rcon
nect
ions
•
Larg
est 3
0-m
inut
e dr
op o
f 450
MW
(bet
wee
n 11
04
and
1134
LS
T) re
pres
ents
abo
ut 2
2.5%
of t
he p
lant
ra
ted
capa
city
•Th
e ev
ent w
as u
nusu
al b
oth
in th
e m
agni
tude
of t
he
90-m
inut
e dr
op a
nd th
e la
rge
geog
raph
ic a
rea
affe
cted
•A
rriv
al o
f suc
h fr
onts
is g
ener
ally
fore
cast
able
, se
vera
l hou
rs a
head
with
in a
30-
min
ute
win
dow
63/
Febr
uary
24,
200
7, 1
400
Loca
l Sta
ndar
d Ti
me
64/
Pro
babi
lity
and
Pre
dict
abili
ty o
f Ram
p E
vent
s•
Fron
tal p
assa
ges/
troug
hs/d
ry li
nes
of a
ny s
ever
ity
occu
r eve
ry 3
-5 d
ays
durin
g co
ld s
easo
n, a
nd e
very
5-7
da
ys d
urin
g w
arm
sea
son
–Fa
st ra
mp-
up e
vent
s (a
s de
fined
for 2
005/
2006
exi
stin
g da
ta)
likel
y to
occ
ur 2
0 tim
es/y
ear o
r eve
ry 2
-3 w
eeks
–Fa
st d
own-
ram
ps li
kely
to o
ccur
onc
e ev
ery
2 m
onth
s•
Con
vect
ive
even
ts o
ccur
with
var
ying
freq
uenc
y–
Num
ber o
f sev
ere
thun
ders
torm
s (w
inds
ove
r 29
m/s
) in
ER
CO
T te
rrito
ry o
ver l
ast 1
0 ye
ars
varie
s fro
m 3
2 in
200
0 to
13
4 in
200
3•
All
wea
ther
phe
nom
ena
caus
ing
ram
p ev
ents
can
be
fore
cast
ed–
Lead
tim
e an
d ac
cura
cy v
arie
s co
nsid
erab
ly–
Fron
tal p
assa
ges
(win
ter)
can
be
fore
cast
ed s
ever
al d
ays
in
adva
nce
with
lim
ited
accu
racy
and
tim
ing,
but
to w
ithin
a 3
0-m
inut
e w
indo
w s
ever
al h
ours
in a
dvan
ce–
Sev
ere
thun
ders
torm
s (s
umm
er) m
ore
diffi
cult
to fo
reca
st,
bette
r for
act
ive
perio
ds –
aver
age
lead
tim
e in
Wes
t Tex
as is
20
min
utes
, 70-
85%
acc
urac
y, b
ut o
nly
30-4
0% d
epen
dabi
lity
65/
Ana
lysi
s of
15,
000
MW
Win
d S
cena
rio
Pres
sure
G
radi
ent
Stre
ngth
enin
g
•A
dditi
onal
ly, s
ince
CR
EZ
10 h
as b
y fa
r the
larg
est w
ind
capa
city
(460
7 M
W),
a sy
stem
affe
ctin
g th
is e
ntire
zon
e co
uld
conc
eiva
bly
resu
lt in
a 3
0-m
inut
e ex
curs
ion
of m
ore
than
110
0 M
W•
An
even
t of t
he m
agni
tude
and
cov
erag
e of
24
Febr
uary
200
7 co
uld
prod
uce
over
a 2
0% re
duct
ion
in p
ower
ove
r mos
t of t
heC
RE
Zs(s
ee ro
w 4
in ta
ble)
onc
e ev
ery
3 -5
yea
rs.
66/
15-M
inut
e W
ind
Sta
te T
rans
ition
Pro
babi
litie
s (1
5,00
0 M
W*)
Pro
babi
lity
that
win
d ou
tput
will
chan
ge fr
om o
ne le
vel t
o an
othe
r with
in 1
5 m
inut
es
Nex
t Sta
te (O
utpu
t, %
rate
d ca
paci
ty)
Current State (Output)
0-10
%11
-20%
21-3
0%31
-40%
41-5
0%51
-60%
61-7
0%71
-80%
81-9
0%91
-100
%
0-10
%0.
8386
0.16
140.
0000
0.00
000.
0000
0.00
000.
0000
0.00
000.
0000
0.00
00
11-2
0%0.
0225
0.86
020.
1173
0.00
000.
0000
0.00
000.
0000
0.00
000.
0000
0.00
00
21-3
0%0.
0000
0.04
860.
8445
0.10
690.
0000
0.00
000.
0000
0.00
000.
0000
0.00
00
31-4
0%0.
0000
0.00
000.
0598
0.82
320.
1170
0.00
000.
0000
0.00
000.
0000
0.00
00
41-5
0%0.
0000
0.00
000.
0000
0.06
550.
8176
0.11
690.
0000
0.00
000.
0000
0.00
00
51-6
0%0.
0000
0.00
000.
0000
0.00
000.
0667
0.80
790.
1253
0.00
000.
0000
0.00
00
61-7
0%0.
0000
0.00
000.
0000
0.00
000.
0000
0.06
410.
8495
0.08
640.
0000
0.00
00
71-8
0%0.
0000
0.00
000.
0000
0.00
000.
0000
0.00
000.
0514
0.87
010.
0785
0.00
00
81-9
0%0.
0000
0.00
000.
0000
0.00
000.
0000
0.00
000.
0000
0.05
160.
9134
0.03
50
91-1
00%
0.00
000.
0000
0.00
000.
0000
0.00
000.
0000
0.00
000.
0000
0.07
910.
9209
•D
iago
nal p
roba
bilit
ies
show
that
on
aver
age
ther
e is
a 8
5%ch
ance
that
win
d ou
tput
w
ill pe
rsis
t –ch
ange
by
no m
ore
that
10%
of r
ated
cap
acity
in fi
fteen
min
utes
–A
vera
ge p
roba
bilit
y of
<7%
that
win
d ou
tput
will
drop
by
mor
e th
an 1
0% o
f rat
ed in
15
min
utes
•N
eglig
ible
cha
nce
that
win
d w
ill ch
ange
by
mor
e th
an 2
0% o
f rat
ed in
15
min
utes
*Fro
m A
WS
T w
ind
prod
uctio
n da
ta
67/
30-M
inut
e W
ind
Sta
te T
rans
ition
Pro
babi
litie
s (1
5,00
0 M
W*)
Pro
babi
lity
that
win
d ou
tput
will
chan
ge fr
om o
ne le
vel t
o an
othe
r with
in 3
0 m
inut
es
Nex
t Sta
te (O
utpu
t, %
rate
d ca
paci
ty)
Current State (Output)
0-10
%11
-20%
21-3
0%31
-40%
41-5
0%51
-60%
61-7
0%71
-80%
81-9
0%91
-100
%
0-10
%0.
8139
0.18
610.
0000
0.00
000.
0000
0.00
000.
0000
0.00
000.
0000
0.00
00
11-2
0%0.
0199
0.80
940.
1707
0.00
000.
0000
0.00
000.
0000
0.00
000.
0000
0.00
00
21-3
0%0.
0000
0.05
950.
7698
0.16
990.
0008
0.00
000.
0000
0.00
000.
0000
0.00
00
31-4
0%0.
0000
0.00
000.
0820
0.73
240.
1835
0.00
210.
0000
0.00
000.
0000
0.00
00
41-5
0%0.
0000
0.00
000.
0000
0.09
160.
7247
0.18
320.
0005
0.00
000.
0000
0.00
00
51-6
0%0.
0000
0.00
000.
0000
0.00
000.
0939
0.72
090.
1847
0.00
050.
0000
0.00
00
61-7
0%0.
0000
0.00
000.
0000
0.00
000.
0011
0.08
790.
7840
0.12
700.
0000
0.00
00
71-8
0%0.
0000
0.00
000.
0000
0.00
000.
0000
0.00
130.
0583
0.83
620.
1042
0.00
00
81-9
0%0.
0000
0.00
000.
0000
0.00
000.
0000
0.00
000.
0000
0.04
770.
9019
0.05
03
91-1
00%
0.00
000.
0000
0.00
000.
0000
0.00
000.
0000
0.00
000.
0000
0.06
580.
9342
•D
iago
nal p
roba
bilit
ies
show
that
on
aver
age
ther
e is
a 8
0%ch
ance
that
win
d ou
tput
will
pers
ist –
chan
ge b
y no
mor
e th
at 1
0% o
f rat
ed c
apac
ity in
30
min
utes
–A
vera
ge p
roba
bilit
y of
<10
% th
at w
ind
outp
ut w
ill dr
op b
y m
ore
than
10%
of r
ated
in 3
0 m
inut
es•
Min
ute
chan
ce th
at w
ind
will
chan
ge b
y m
ore
than
20%
of r
ated
in30
min
utes
•P
ersi
sten
ce is
gre
ater
at h
igh
and
low
out
put l
evel
s*F
rom
AW
ST
win
d pr
oduc
tion
data
68/
1-H
our W
ind
Sta
te T
rans
ition
Pro
babi
litie
s (1
5,00
0 M
W*)
Pro
babi
lity
that
win
d ou
tput
will
chan
ge fr
om o
ne le
vel t
o an
othe
r with
in 6
0 m
inut
es
Nex
t Sta
te (O
utpu
t, %
rate
d ca
paci
ty)
Current State (Output)
0-10
%11
-20%
21-3
0%31
-40%
41-5
0%51
-60%
61-7
0%71
-80%
81-9
0%91
-100
%
0-10
%0.
7244
0.27
420.
0014
0.00
000.
0000
0.00
000.
0000
0.00
000.
0000
0.00
00
11-2
0%0.
0590
0.68
810.
2419
0.01
030.
0007
0.00
000.
0000
0.00
000.
0000
0.00
00
21-3
0%0.
0000
0.13
980.
6106
0.22
500.
0246
0.00
000.
0000
0.00
000.
0000
0.00
00
31-4
0%0.
0000
0.00
430.
1845
0.55
270.
2355
0.02
210.
0009
0.00
000.
0000
0.00
00
41-5
0%0.
0000
0.00
000.
0066
0.19
150.
5315
0.23
570.
0347
0.00
000.
0000
0.00
00
51-6
0%0.
0000
0.00
000.
0000
0.01
610.
1847
0.54
320.
2390
0.01
710.
0000
0.00
00
61-7
0%0.
0000
0.00
000.
0000
0.00
000.
0149
0.19
430.
5934
0.18
900.
0085
0.00
00
71-8
0%0.
0000
0.00
000.
0000
0.00
000.
0000
0.00
390.
1399
0.72
420.
1320
0.00
00
81-9
0%0.
0000
0.00
000.
0000
0.00
000.
0000
0.00
000.
0077
0.12
310.
8077
0.06
15
91-1
00%
0.00
000.
0000
0.00
000.
0000
0.00
000.
0000
0.00
000.
0286
0.14
290.
8286
•D
iago
nal p
roba
bilit
ies
show
that
on
aver
age
ther
e is
a 6
6%ch
ance
that
win
d ou
tput
will
pers
ist –
chan
ge b
y no
mor
e th
at 1
0% o
f rat
ed c
apac
ity in
60
min
utes
–A
vera
ge p
roba
bilit
y of
<18
% t
hat w
ind
will
chan
ge b
y m
ore
than
10%
of r
ated
in 6
0 m
inut
es•
Sm
all c
hanc
e th
at w
ind
will
chan
ge b
y m
ore
than
20%
of r
ated
in 6
0 m
inut
es•
Per
sist
ence
is s
igni
fican
tly g
reat
er a
t hig
h an
d lo
w o
utpu
t lev
els
*Fro
m A
WS
T w
ind
prod
uctio
n da
ta
69/
Larg
est O
ne-H
our W
ind
Dro
p in
15,
000
MW
Win
d (J
an 2
8 ’0
6)Ja
nuar
y 28
, 200
6 W
ind
Nega
tive
Ram
p Ev
ent
0.0
500.
0
1000
.0
1500
.0
2000
.0
2500
.0
3000
.0
3500
.0
4000
.0
4500
.0
5000
.0
3:00 P
M
4:00 P
M
5:00 P
M
6:00 P
M
7:00 P
M
8:00 P
M
9:00 P
M
Tim
e (C
ST)
CREZ Output (MW)
0.0
2000
.0
4000
.0
6000
.0
8000
.0
1000
0.0
1200
0.0
1400
0.0
15,000 MW Wind Scenario Output (MW)
2 5 6 7 9 10 12 14 15 19 23 24 Tota
l
TOTA
L
CR
EZ 1
0
CR
EZ 2
CR
EZ 9
CR
EZ 2
4 CR
EZ 6
CR
EZ 5
CR
EZ 1
2 Win
d dr
ops
by 3
340
MW
in o
ne h
our,
driv
en la
rgel
y by
an
alm
ost 2
000
MW
one
-hou
r dro
p in
CR
EZ
10
70/
Larg
est O
ne-H
our W
ind
Dro
p in
CR
EZ
10 W
ind
(Jan
28
’06)
Janu
ary
28 E
vent
in C
REZ
10
0.0
50.0
100.
0
150.
0
200.
0
250.
0
300.
0
350.
0
400.
0
9:00 P
M
10:00
PM
11:00
PM
12:00
AM
1:00 A
M
2:00 A
M
3:00 A
MSite Output (MW)
0.0
600.
0
1200
.0
1800
.0
2400
.0
3000
.0
3600
.0
4200
.0
4800
.03
2993
9614
818
319
519
822
422
523
726
028
831
132
137
538
838
940
342
643
144
246
246
547
349
149
449
852
452
752
853
654
2To
tal
CR
EZ T
OTA
L
SITE
237 SITE
96
SITE
462
SITE
321
SITE
198
SITE
465
SITE
3
CREZ Output (MW)
Mos
t site
s in
CR
EZ
10 a
re s
imila
rly im
pact
ed b
y th
e ev
ent
71/
0
400
800
1200
1600
2000
2400
2800
3200
3600
4000
4400
4800
< -1500-1500 – -1400-1400 – -1300-1300 – -1200-1200 – -1100-1100 – -1000-1000 – -900-900 – -800-800 – -700-700 – -600-600 – -500-500 – -400-400 – -300-300 – -200-200 – -100-100 – 00 – 100100 – 200200 – 300300 – 400400 – 500500 – 600600 – 700700 – 800800 – 900900 – 10001000 – 11001100 – 12001200 – 13001300 – 14001400 – 1500> 1500
MW
30-Minute Periods
5000
MW
Win
d10
000
MW
Win
d (1
)10
000
MW
Win
d (2
)15
000
MW
Win
d
Dis
tribu
tion
of T
hirty
-Min
ute
Win
d O
utpu
t Cha
nges
(Del
tas)
(Stu
dy Y
ear)
Var
iabi
lity
(σ) d
oes
not
incr
ease
line
arly
with
win
d pe
netra
tion,
but
Impa
ct o
f di
vers
ity is
less
pro
noun
ced
for l
onge
r tim
e pe
riods
78 /
117
197
/ 270
314
-224
/ 23
7
1000
0 M
W (1
)
81 /
103
189
/ 258
288
-208
/ 21
5
1000
0 M
W (2
)
-304
/ 31
3-1
28 /
138
Mea
n (-/
+)
203
/ 262
171
/ 318
> µ
±2.
5σ (−
/+)
> µ
±3.
0σ (−
/+)
Sigm
a
83 /
9875
/ 12
8
420
183
1500
0 M
W50
00 M
W
130%
in
crea
se in
σfo
r 200
%
incr
ease
in
win
d
72/
0
200
400
600
800
1000
1200
1400
1600
1800
2000
< -3000-3000 – -2800-2800 – -2600-2600 – -2400-2400 – -2200-2200 – -2000-2000 – -1800-1800 – -1600-1600 – -1400-1400 – -1200-1200 – -1000-1000 – -800-800 – -600-600 – -400-400 – -200-200 – 00 – 200200 – 400400 – 600600 – 800800 – 10001000 – 12001200 – 14001400 – 16001600 – 18001800 – 20002000 – 22002200 – 24002400 – 26002600 – 28002800 – 3000> 3000
MW
30-Minute Periods
Del
ta L
oad
Del
ta L
-500
0D
elta
L-1
5,00
0
Dis
tribu
tion
of T
hirty
-Min
ute
Net
Loa
d C
hang
es (D
elta
s)(S
tudy
Yea
r)
9 / 1
0
104
/ 79
1013
-797
/ 80
1
L-10
000
MW
(2)
10 /
1312
/ 9
5 / 1
31
/ 19
> µ
±3.
0σ (−
/+)
102
/ 88
86 /
7596
/ 76
71 /
80>
µ±
2.5σ
(−/+
)
967
-755
/ 77
1
L-50
00 M
W
1031
-816
/ 81
1
L-10
000
MW
(1)
-857
/ 85
0-6
95 /
741
Mea
n (-/
+)
Sigm
a (σ
)10
8391
1
L-15
000
MW
Load
-alo
ne
73/
0102030405060708090100
-260
0-2
200
-180
0-1
400
-100
0-6
00-2
00
Win
d D
elta
(MW
)
Number of 30-Minute Periods
5000
MW
1000
0 M
W(1
)10
000
MW
(2)
1500
0 M
W
Ext
rem
e Th
irty-
Min
ute
Win
d D
rops
(Dow
n-R
amps
)
(S
tudy
Yea
r)
2300
MW
(Spi
nnin
g R
eser
ves)
Win
d do
wn-
ram
p eq
uals
or e
xcee
ds
onlin
e re
serv
es (2
300
MW
) thr
ee ti
mes
w
ith15
,000
MW
of
win
d pr
oduc
tion
249
3663
5N
o. D
rops
> 10
00 M
W
30
00
No.
Dro
ps>
2300
MW
-256
3-1
771
-205
3-1
167
Max
Neg
Del
ta
1629
10,0
00 M
W
Win
d (2
)
1611
10,0
00 M
W
Win
d (1
)
2370
1079
Max
Pos
Del
ta
5000
MW
W
ind
15,0
00 M
W
Win
d
74/
0102030405060
2200
2400
2600
2800
3000
3200
3400
3600
3800
4000
Net
-Loa
d D
elta
(MW
)
Number of 30-Minute Periods
Load
-Alo
neL-
5000
MW
L-10
000
MW
(1)
L-10
000
MW
(2)
L-15
000
MW
Ext
rem
e Th
irty-
Min
ute
Net
-Loa
d R
ises
(Up-
Ram
ps)
(S
tudy
Yea
r)
3101
MW
Max
load
-alo
ne
30-m
in u
p-ra
mp
Net
load
up-
ram
p eq
uals
or
exce
eds
the
max
load
-al
one
up-ra
mp
(310
1 M
W)
24 ti
mes
, with
15,
000
MW
of
win
d
168
2916
-330
0
3805
L-10
,000
MW
W
ind
(2)
3092
2986
2769
2557
No.
Ris
es>
1000
MW
289
191
114
78N
o. R
ises
> 23
00 M
W
-361
2-3
360
-313
8-2
756
Max
Neg
Del
ta
3928
L-10
,000
MW
W
ind
(1)
3271
L-50
00 M
W
Win
d (1
)
4502
3101
Max
Pos
Del
ta
Load
-alo
neL-
15,0
00
MW
Win
d
75/
Tim
ing
of E
xtre
me
Thirt
y-M
inut
e W
ind
Dro
ps
(S
tudy
Yea
r)
12
34
56
78
910
1112
1314
1516
1718
1920
2122
2324
Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Sep
Oct
Nov
Dec
Hou
r of D
ay
Month of Year
-800
--200
-140
0--8
00-2
000-
-140
0-2
600-
-200
0
Larg
est 3
0-m
inut
e w
ind
drop
s te
nd to
occ
ur in
th
e m
orni
ng 6
-9 A
M a
nd la
te a
ftern
oon
5-7
PM
(e
xcep
t in
the
Sum
mer
)
Cor
resp
onds
with
RE
G o
bser
vatio
ns-256
3 M
W
-247
9 M
W
-230
0 M
W
76/
Con
clus
ions
–Ex
trem
e W
eath
er C
ondi
tions
•La
rge
sudd
en w
ind
excu
rsio
ns (g
reat
er th
an 2
0% o
f ra
ted
capa
city
with
in 3
0 m
inut
es) a
re in
frequ
ent
–C
hang
es o
ccur
as
fast
ram
ps, n
ot s
teps
•W
hen
sudd
en c
hang
es d
o oc
cur,
CR
EZ
dive
rsity
si
gnifi
cant
ly re
duce
s th
e im
pact
of a
ny s
ingl
e ch
ange
on
the
aggr
egat
e ou
tput
•
Wea
ther
eve
nts
caus
ing
wid
espr
ead
impa
ct a
re
reas
onab
ly p
redi
ctab
le
•Lo
cal c
onve
ctiv
e ev
ents
are
less
pre
dict
able
–Te
nd to
hav
e a
limite
d ge
ogra
phic
ext
ent
–La
rge
win
d co
ncen
tratio
ns in
crea
se v
ulne
rabi
lity
77/
Con
clus
ions
-Im
pact
on
Spi
nnin
g R
eser
ves
•M
axim
um 1
5 m
inut
e w
ind
drop
for 1
5,00
0 M
W s
cena
rio is
13
37 M
W; w
ell w
ithin
pre
sent
230
0 M
W R
RS
•A
cros
s th
e ye
ar, t
hree
obs
erve
d ca
ses
whe
n w
ind
drop
s by
ov
er 2
300
MW
in 3
0 m
inut
es–
Late
afte
rnoo
n S
epte
mbe
r 21,
Jan
uary
28,
Dec
embe
r 30
–S
ome
seve
re d
rops
will
inhe
rent
ly fa
ll in
per
iods
of
“unc
erta
in w
eath
er” w
here
rese
rves
are
alre
ady
boos
ted
•Lo
ad-a
lone
has
ext
rem
e up
-ram
ps, b
ut w
ind
crea
tes
incr
emen
tal r
equi
rem
ents
in n
et lo
ad, m
ostly
in m
orni
ngs
and
late
win
ter a
ftern
oons
•A
ltern
ativ
e ap
proa
ches
:–
Incr
ease
RR
S fo
r per
iods
of f
orec
ast “
met
eoro
logi
cal r
isk”
–R
evis
e th
e N
SR
S d
efin
ition
to p
rovi
de fo
r a 1
5-m
inut
e re
spon
se s
ervi
ce; p
rocu
re th
is s
ervi
ce a
t per
iods
of
desi
gnat
ed ri
sk
78/
Reg
ulat
ion
Req
uire
men
ts
79/
In th
is n
ext s
et o
f slid
es, w
e w
ill sh
ow:
•H
ow re
gula
tion
in th
e E
RC
OT
noda
l mar
ket i
s ca
lcul
ated
in th
is s
tudy
•R
egul
atio
n re
quire
d (d
eplo
yed)
Key
issu
es a
re:
•D
iffer
ence
s w
ith re
gula
tion
requ
irem
ents
in th
e pr
esen
t zon
al m
arke
t•
Cha
nges
in re
gula
tion
requ
irem
ents
with
incr
ease
d w
ind
pene
tratio
n
80/
Dis
patc
h P
roce
dure
in th
e E
RC
OT
Nod
al M
arke
t
•E
cono
mic
dis
patc
h is
on
a 5-
min
ute
basi
s;
•E
RC
OT
is c
onsi
derin
g pr
edic
tive
tuni
ng fa
ctor
s to
redu
ce
regu
latio
n re
quire
men
ts d
riven
by
load
follo
win
g–
Dis
patc
h se
tpoi
nt is
initi
al a
ctua
l loa
d +
ktim
es e
xpec
ted
chan
ge
over
5-m
inut
e pe
riod
–Tu
ning
fact
ors
have
not
yet
bee
n re
solv
ed
•S
cope
of t
his
stud
y fo
cuse
s on
win
d, n
ot o
pera
ting
prac
tices
in
depe
nden
t of w
ind
–R
egul
atio
n re
sults
are
inte
nded
for r
elat
ive
com
paris
on b
etw
een
win
d sc
enar
ios
–C
ompa
rison
with
pre
sent
regu
latio
n re
quire
men
ts a
re n
ot
appr
opria
te
•A
ssum
ing
k =
0 m
axim
izes
impa
ct o
f ram
p ra
te; m
ost
cons
erva
tive
with
resp
ect t
o w
ind
impa
ct
81/
Reg
ulat
ion
Cal
cula
tion
in th
e N
odal
Mar
ket
•U
nits
on
econ
omic
disp
atch
“ste
p” to
set
poin
tsat
dis
cret
e 5-
min
ute
poin
ts•
Diff
eren
ce b
etw
een
actu
al
load
and
eco
nom
ic
setp
oint
sis
def
ined
as
regu
latio
n–
Pos
itive
dev
iatio
ns d
efin
ed
as “U
p R
eg” (
+RE
G)
–N
egat
ive
devi
atio
ns
defin
ed a
s “D
own
Reg
” (-
RE
G)
37,6
60
37,6
80
37,7
00
37,7
20
37,7
40
37,7
60
37,7
80
37,8
00
910
915
920
925
930
Min
ute
MW
Load
Set
poin
t
-100-50050
Regulation (MW)
82/
28,0
00
28,2
00
28,4
00
28,6
00
28,8
00
29,0
00
29,2
00
29,4
00
1020
3040
5060
Min
utes
MW
Load
Setp
oint
s
-REG
-500
-400
-300
-200
-1000
100
200
300
400
500
05
1015
2025
Hou
rs
MW
05,00
0
10,0
00
15,0
00
20,0
00
25,0
00
30,0
00
35,0
00
40,0
00
45,0
00
50,0
00
Inst
. Reg
ulat
ion
+REG
-REG
Load
Dis
patc
hed
Gen
.
Reg
ulat
ion
Thro
ugh
a Ty
pica
l Day
(with
out w
ind)
•R
egul
atio
n is
bia
sed
by lo
ad ra
mp
rate
–no
t jus
t the
“ran
dom
jitte
r” c
ompo
nent
–V
irtua
lly n
o D
own
Reg
dur
ing
load
rise
–V
irtua
lly n
o U
p R
eg d
urin
g lo
ad d
rop
83/
Term
inol
ogy
and
Abb
revi
atio
ns
The
follo
win
g te
rmin
olog
y an
d ab
brev
iatio
ns re
gard
ing
regu
latio
n ar
e us
ed in
this
pre
sent
atio
n:D
eplo
yed
Reg
ulat
ion
–M
axim
um d
iffer
ence
ove
r eac
h 5-
min
ute
perio
d be
twee
n th
e ne
t loa
d an
d th
e di
spat
ch
base
poi
nt (a
ctua
l net
load
at t
he b
egin
ning
of p
erio
d)Pr
ocur
ed R
egul
atio
n–
Amou
nt o
f reg
ulat
ion
“res
erve
d”
base
d on
sta
tistic
al a
naly
sis
of p
rior d
eplo
ymen
ts+R
EG –
Up
Reg
ulat
ion
–P
ositi
ve d
iffer
ence
bet
wee
n ne
t lo
ad a
nd b
ase
poin
t.-R
EG –
Dow
n R
egul
atio
n-D
iffer
ence
bet
wee
n ne
t loa
d an
d ba
se p
oint
(exp
ress
ed in
this
pre
sent
atio
n as
a
nega
tive
num
ber)
84/
Max
. Hou
rly D
eplo
yed
Reg
ulat
ion
–Ja
nuar
y E
xam
ple
•~4
day
tim
e pe
riod
plot
ted
•D
iurn
al p
atte
rns
visi
ble
•~4
day
s pl
otte
d•
Diu
rnal
pat
tern
in R
EG
are
vi
sibl
e•
Sig
nific
ant i
mpa
ct o
f out
liers
–A
few
driv
en b
y w
ind
–M
ost o
utlie
rs c
hang
ed
incr
emen
tally
–S
ome
not c
hang
ed a
t all
Janu
ary
-800
-600
-400
-2000
200
400
600
800
2535
4555
6575
8595
105
115
125
Hou
r
Max. Hourly +/-REG
Load
Alo
neLo
ad-5
000
Load
-100
00(1
)Lo
ad-1
0000
(2)
Load
-150
00
0
200
400
600
Peak
ca
used
by
win
d
Peak
is
~sam
e
85/
Dep
loye
d R
egul
atio
n S
tatis
tics
Up-
Reg
ulat
ion
1124
.9 M
W11
12.7
MW
1105
.6 M
W10
75.9
MW
1072
.5 M
W
Max
imum
23.1
%12
.7%
14.2
%6.
4%%
Cha
nge
3.7%
261.
5 M
W10
.2%
81.4
MW
10,0
00 (2
)4.
9%28
5.8
MW
16.5
%86
.1 M
W15
,000
3.1%
265.
2 M
W11
.7%
82.5
MW
10,0
00 (1
)0.
3%24
7.0
MW
5.8%
78.1
MW
5,00
023
2.1
MW
73.8
MW
0
%
Cha
nge
98th
Per
cent
ile o
f 5-
min
Per
iods
%
Cha
nge
Ave
rage
Max
of
5-m
in P
erio
dsW
ind
(MW
)
-566
.4-5
65.9
-554
.9-5
38.9
-522
.2
Min
imum
20.7
%11
.8%
12.8
%5.
9%%
Cha
nge
8.4%
-260
.4 M
W9.
7%-8
1.5
MW
10,0
00 (2
)8.
5%-2
81.2
MW
16.5
%-8
6.6
MW
15,0
00
6.3%
-262
.7 M
W11
.7%
-83.
0 M
W10
,000
(1)
3.2%
-246
.7 M
W5.
8%-7
8.6
MW
5,00
0-2
33.0
MW
-74.
3 M
W0
%
Cha
nge
98th
Per
cent
ile o
f 5-
min
Per
iods
%
Cha
nge
Ave
rage
Min
of
5-m
in P
erio
dsW
ind
(MW
)
Dow
n-R
egul
atio
n
86/
Cum
ulat
ive
Dis
tribu
tions
of M
axim
um H
ourly
Up-
Reg
ulat
ion
050100
150
200
250
300
350
400
087
617
5226
2835
0443
8052
5661
3270
0878
8487
60
Hou
rs
+REG (MW)
Load
Alo
neL-
5000
L-10
000(
1)
L-10
000(
2)
L-15
000
Expa
nsio
n of
0-4
00 M
W
rang
e
0
200
400
600
800
1000
1200
1400
087
617
5226
2835
0443
8052
5661
3270
0878
8487
60
Hou
rs
+REG (MW)
Load
Alo
neL-
5000
L-10
000(
1)
L-10
000(
2)
L-15
000
87/
-400
-350
-300
-250
-200
-150
-100-5
00
087
617
5226
2835
0443
8052
5661
3270
0878
8487
60
Hou
rs -R
EG M
ore
Neg
ativ
e Th
an V
alue
-REG (MW)
Load
Alo
neL-
5000
L-10
000(
1)L-
1000
0(2)
L-
1500
0
Cum
ulat
ive
Dis
tribu
tions
of M
axim
um H
ourly
Dow
n-R
egul
atio
n
Expa
nsio
n of
0 -
-400
MW
rang
e
-140
0
-120
0
-100
0
-800
-600
-400
-2000
087
617
5226
2835
0443
8052
5661
3270
0878
8487
60
Hou
rs
-REG (MW)
Load
Alo
neL-
5000
L-10
000(
1)L-
1000
0(2)
L-
1500
0
88/
Ext
rem
e U
p-R
egul
atio
n an
d D
own-
Reg
ulat
ion
-150
0
-140
0
-130
0
-120
0
-110
0
-100
0
-900
-800
-700
-600
-500
020
4060
8010
0
Hou
rs
-REG (MW)
Load
Alo
neL-
5000
L-10
000(
1)L-
1000
0(2)
L-
1500
0
600
700
800
900
1000
1100
1200
1300
1400
020
4060
8010
0
Hou
rs
+REG (MW)
Load
Alo
neL-
5000
L-10
000(
1)
L-10
000(
2)
L-15
000
Exc
ept f
or a
n ex
trem
e ou
tlier
in
one
10G
W w
ind
scen
ario
, m
axim
um, e
xtre
me
+/-R
EG
is
incr
ease
d m
odes
tly.
Incr
ease
≈pr
opor
tiona
te w
ith th
e am
ount
of w
ind
reso
urce
s≈
100
MW
incr
ease
100
hrs
is ≈
1.2%
of y
ear
89/
Hou
rly M
axim
um R
egul
atio
n In
crea
se w
ith 1
5,00
0 M
W W
ind
0%5%10%
15%
20%
25%
−280 → −300 −260 → −280 −240 → −260 −220 → −240 −200 → 220 −180 → −200 −160 → −180 −140 → −160 −120 → −140 −100 → −120 −80 → −100 −60 → −80 −40 → −60 −20 → −40 0 → −20 0 → 20 20 → 40 40 → 60 60 → 80 80 → 100 100 → 120 120 → 140 140 → 160 160 → 180 180 → 200 200 → 220 220 → 240 240 → 260 260 → 280 280 → 300
Cha
nge
in R
egul
atio
n
Percent of Hours+R
EG
-RE
G
Diff
eren
ce b
etw
een
hour
ly m
ax. r
egul
atio
n fo
r loa
d on
ly a
nd lo
ad–1
5GW
win
d
-18.
217
.7M
ean
-287
.2
444.
2
64.9
+REG
265.
3M
axim
um
Min
imum
Sig
ma
-453
.1
65.1
-REG
Res
ults
are
≈
sym
met
ric
Thes
e st
atis
tics
desc
ribe
the
max
imum
regu
latio
n w
ithin
ea
ch 1
-hr p
erio
d
90/
Up
Reg
ulat
ion
Cor
rela
tion
with
Tim
e of
Day
and
Mon
th98
.8th
Perc
entil
e of
+R
EG D
eplo
yed
1
3
5
7
9
11
13
15
17
19
21
23
Jan
Mar
May
Jul
Sep
Nov
600-
800
400-
600
200-
400
0-20
0
Load
Alo
ne
1
3
5
7
9
11
13
15
17
19
21
23
Jan
Mar
May
Jul
Sep
Nov
800-
1000
600-
800
400-
600
200-
400
0-20
0
Load
–50
00 M
W W
ind
Load
–10
,000
MW
Win
d (1
)Lo
ad –
15,0
00 M
W W
ind
1
3
5
7
9
11
13
15
17
19
21
23
Jan
Mar
May
Jul
Sep
Nov
800-
1000
600-
800
400-
600
200-
400
0-20
01
3
5
7
9
11
13
15
17
19
21
23
Jan
Mar
May
Jul
Sep
Nov
800-
1000
600-
800
400-
600
200-
400
0-20
0
91/
Diff
eren
tial U
p R
egul
atio
n R
equi
rem
ents
for 1
5 G
W W
ind
1
3
5
7
9
11
13
15
17
19
21
23
Jan
Mar
May
Jul
Sep
Nov
250-
300
200-
250
150-
200
100-
150
50-1
000-
50-5
0-0
-100
--50
98.8
thPe
rcen
tile
of +
REG
Dep
loye
d
•In
crea
ses
durin
g m
orni
ng lo
ad ra
mp
due
to w
ind
decl
ine
•In
crea
ses
durin
g ea
rly e
veni
ng d
urin
g sp
ring
and
fall
92/
Diff
eren
tial D
own
Reg
ulat
ion
Req
uire
men
ts fo
r 15
GW
Win
d98
.8th
Perc
entil
e of
–R
EG D
eplo
yed
1
3
5
7
9
11
13
15
17
19
21
23
Jan
Mar
May
Jul
Sep
Nov
50-1
000-
50-5
0-0
-100
--50
-150
--100
-200
--150
-250
--200
-300
--250
•M
ore
dow
n re
gula
tion
in th
e ev
enin
g, p
artic
ular
ly in
fall,
w
inte
r and
spr
ing
•D
ecre
ased
dow
n re
gula
tion
durin
g su
mm
er m
orni
ngs
93/
Var
iatio
n in
Up
Reg
ulat
ion
for S
elec
ted
Per
iods
0
100
200
300
400
500
600
050
0010
000
1500
0W
ind
Cap
acity
(MW
)
+REG (average monthly 98.8
th percentile)
Mor
ning
(070
0 - 1
000)
Even
ing
(180
0)M
id-D
ay (1
400)
Nig
ht (2
300)
+16.
3%
+52.
0%
+65.
2%
+25.
6%
•R
elat
ive
impa
ct is
not
uni
form
, win
d do
es s
ubst
antia
lly in
crea
sere
gula
tion
requ
irem
ents
at t
imes
whe
n re
gula
tion
requ
irem
ents
had
be
en s
mal
l to
mod
erat
e•
Line
arity
allo
ws
scal
e-up
of r
egul
atio
n pr
ocur
emen
t to
acco
mm
odat
e ye
ar-to
-yea
r win
d ad
ditio
ns
94/
Incr
ease
of E
veni
ng D
own
Reg
ulat
ion
Req
uire
men
ts
-600
-500
-400
-300
-200
-1000
050
0010
000
1500
0
Win
d C
apac
ity (M
W)
-REG (average monthly 98th percentile)
31.9
%
Eve
ning
win
d in
crea
se c
oinc
ides
with
load
dro
p
95/
Impa
ct o
f Win
d P
enet
ratio
n on
Reg
ulat
ion
•R
egul
atio
n pe
aks
caus
ed b
y lo
ad ra
mpi
ng a
re in
crem
enta
lly
incr
ease
d du
e to
add
ed ra
mp
caus
ed b
y w
ind
•R
elat
ive
to lo
ad a
lone
, 98t
h pe
rcen
tile
of re
gula
tion
incr
ease
s on
the
orde
r of 2
0% -
23%
at 1
5 G
W o
f win
d
•R
egul
atio
n in
crea
ses
linea
rly w
ith w
ind
pene
tratio
n
•E
xtre
ma
appe
ar b
oth
with
and
with
out w
ind,
with
m
agni
tude
s in
crem
enta
lly g
reat
er w
ith 1
5 G
W o
f win
d
•La
rges
t cha
nges
are
con
cent
rate
d in
par
ticul
ar ti
mes
of d
ay
and
seas
ons
--+R
EG
in th
e ev
enin
gs in
crea
ses
65%
96/
Eva
luat
ion
of R
egul
atio
nP
rocu
rem
ent M
etho
dolo
gy
97/
In th
is n
ext s
et o
f slid
es, w
e w
ill sh
ow:
•H
ow E
RC
OT
pres
ently
det
erm
ines
the
amou
nt o
f re
gula
tion
to p
rocu
re•
The
robu
stne
ss o
f thi
s m
etho
dolo
gy to
incr
ease
d w
ind
pene
tratio
nK
ey is
sues
are
:•
Freq
uenc
y of
und
er-p
rocu
rem
ent
•S
ever
ity o
f und
er-p
rocu
rem
ent
98/
ER
CO
T R
egul
atio
n P
rocu
rem
ent M
etho
dolo
gy
0
100
200
300
400
500
600
700
800
2535
4555
6575
Hou
r
Max. Hourly +REG
Dep
loye
d +R
EG, L
oad
Alon
ePr
ocur
ed +
REG
, Loa
d Al
one
Dep
loye
d >
Pro
cure
d
•R
egul
atio
n pr
ocur
emen
t alg
orith
m s
eeks
to c
over
mos
t, bu
t not
all
time
perio
ds; o
ccas
iona
l “m
isse
s” a
re e
xpec
ted
•P
rocu
rem
ent b
ased
on
98.8
thpe
rcen
tile
of m
axim
um d
eplo
ymen
t in
5-m
inut
e in
terv
als
for s
ame
hour
of d
ay in
:–
Sam
e m
onth
, prio
r yea
r–
Prio
r mon
th, s
ame
year
99/
Reg
ulat
ion
Dep
loye
d vs
. Pro
cure
d Ti
me
Ser
ies
Exa
mpl
e Ja
nuar
y w
ith 1
5,00
0 M
W W
ind
Janu
ary
0
100
200
300
400
500
600
700
800
2535
4555
6575
Hou
r
Max. Hourly +REG
Dep
l., L
oad
Dep
l., L
-15G
W
Proc
., Lo
adPr
oc.,
L-15
GW
•P
rocu
rem
ent m
odifi
ed (g
ener
ally
incr
ease
d) d
ue to
win
d (h
isto
rical
pre
senc
e of
win
d as
sum
ed)
“Mis
s” c
ause
d by
win
dP
eak
incr
emen
tally
in
crea
sed
100
/
Cha
nges
in D
eplo
yed
and
Pro
cure
d R
egul
atio
n
0
200
400
600
800
1000
1200
050
0010
000
1500
0
Win
d C
apac
ity (M
W)
Up Regulation (MW)
Max
Dep
loye
d98
.8 p
ct D
eplo
yed
Mea
n D
eplo
yed
Mea
n Pr
ocur
edM
ax. P
rocu
red
+4.9
%
+23.
1%
+16.
5%-8
00
-700
-600
-500
-400
-300
-200
-1000
050
0010
000
1500
0
Win
d C
apac
ity (M
W)
Down Regulation (MW)
Min
Dep
loye
d98
.8 p
ct D
eplo
yed
Mea
n D
eplo
yed
Mea
n Pr
ocur
edM
in. P
rocu
red
16.5
%
20.7
%
8.5%
•G
ap b
etw
een
max
imum
dep
loye
d an
d m
axim
um
proc
ured
nar
row
s as
win
d pe
netra
tion
incr
ease
s•
Poi
nt o
f com
paris
on: s
igm
a of
5-m
in d
elta
incr
ease
d 18
% fr
om lo
ad a
lone
to lo
ad m
inus
15
GW
of w
ind
101
/
Up
Reg
ulat
ion
Freq
uenc
y D
istri
butio
n E
xam
ples
Janu
ary
- 140
0
020406080100
120
140
160
0
100
200
300
400
500
600
700
800
900
1000
MW
Number of 5 min Periods
Load
Load
- 15
000
MW
209
MW
+R
EG P
rocu
red
for
Load
- 15
GW
140
MW
+R
EG P
rocu
red
for L
oad
Alon
e
April
- 13
00
0102030405060
0
100
200
300
400
500
600
700
800
900
1000
MW
Number of 5 min Periods
Load
Load
- 15
000
MW
259
MW
+R
EG P
rocu
red
for L
oad
- 15G
W
224
MW
+R
EG P
rocu
red
for L
oad
Alon
e
Larg
e U
nder
-Pro
cure
men
t Mag
nitu
de
Hig
h Fr
eque
ncy
of U
nder
-Pro
cure
mee
nt
102
/
Per
cent
age
of H
ours
with
+R
EG
Und
er-P
rocu
rem
ent
1
3
5
7
9
11
13
15
17
19
21
23
Jan
Mar
May
Jul
Sep
Nov
5.0%
-6.0
%4.
0%-5
.0%
3.0%
-4.0
%2.
0%-3
.0%
1.0%
-2.0
%0.
0%-1
.0%
Load
Alo
ne
Load
–15
,000
MW
Win
d
1
3
5
7
9
11
13
15
17
19
21
23
Jan
Mar
May
Jul
Sep
Nov
5.0%
-6.0
%4.
0%-5
.0%
3.0%
-4.0
%2.
0%-3
.0%
1.0%
-2.0
%0.
0%-1
.0%
14.7
% p
eak
11.7
% p
eak
Pres
ent a
ppro
ach
has
a re
lativ
ely
larg
e nu
mbe
r of
mis
ses
in th
e sp
ring
(mor
ning
to m
id-
afte
rnoo
n) a
nd a
utum
n ev
enin
gs
Incr
ease
d ov
eral
l +R
EG
depl
oym
ent w
ith 1
5 G
W
of w
ind
dim
inis
hes
the
high
con
cent
ratio
n of
m
isse
s du
ring
thes
e pe
riods
A fe
w li
mite
d po
ints
wer
e so
mew
hat m
ore
seve
re
10.3
% p
eak
103
/
Roo
t Mea
n S
quar
e of
+R
EG
Und
er-P
rocu
rem
ent
Load
Alo
neLo
ad –
15,0
00 M
W W
ind
1
3
5
7
9
11
13
15
17
19
21
23
Jan
Mar
May
Jul
Sep
Nov
300-
400
200-
300
100-
200
0-10
0
0 0 0 0
1
3
5
7
9
11
13
15
17
19
21
23
Jan
Mar
May
Jul
Sep
Nov
400-
5030
0-40
200-
3010
0-20
0-10
0
1
3
5
7
9
11
13
15
17
19
21
23
Jan
Mar
May
Jul
Sep
Nov
0-10
0
-100
-0
-200
--100
Diff
eren
ce
104
/
Reg
ulat
ion
Und
er-P
rocu
rem
ent S
tatis
tics
•P
rese
nt m
etho
dolo
gy p
rodu
ces
regu
latio
n re
quire
men
ts
cons
iste
nt w
ith c
urre
nt a
ccur
acy
•G
row
th in
abs
olut
e m
agni
tude
of d
efic
ienc
ies
com
men
sura
te w
ith re
gula
tion
incr
ease88
.5 M
W84
.2 M
W85
.0 M
W82
.1 M
W80
.1 M
W
RM
Sof
Def
icie
ncy
643
MW
50.8
MW
6,00
41.
35%
10,0
00 (2
)63
2 M
W55
.9 M
W6,
712
1.37
%15
,000
638
MW
52.0
MW
6,20
11.
36%
10,0
00 (1
)63
4 M
W48
.2 M
W5,
320
1.26
%50
0065
3 M
W45
.5 M
W5,
141
1.29
%0
Extr
eme
Def
icie
ncy
Ave
rage
Und
er-P
roc.
Tota
l MW
hU
nder
-Pro
c.Pe
rcen
tage
of
Per
iods
Win
dU
p-R
egul
atio
n
90.1
MW
89.2
MW
87.9
MW
90.4
MW
89.2
MW
RM
Sof
Def
icie
ncy
940
MW
52.2
MW
5,30
11.
16%
10,0
00 (2
)92
7 M
W54
.7 M
W5,
562
1.16
%15
,000
946
MW
51.7
MW
5,43
91.
20%
10,0
00 (1
)91
1 M
W52
.5 M
W5,
148
1.12
%50
0088
6 M
W48
.5 M
W5,
011
1.18
%0
Extr
eme
Def
icie
ncy
Ave
rage
Und
er-P
roc.
Tota
l MW
hU
nder
-Pro
c.Pe
rcen
tage
of
Per
iods
Win
dD
own-
Reg
ulat
ion
105
/
In s
umm
ary:
•R
egul
atio
n re
quire
men
ts fo
r net
load
with
hig
h w
ind
pene
tratio
n ar
e st
atis
tical
ly a
s “w
ell b
ehav
ed” a
s lo
ad o
nly
•Th
e pr
esen
t ER
CO
T m
etho
dolo
gy fo
r det
erm
inin
g th
e am
ount
of r
egul
atio
n to
pro
cure
rem
ains
effe
ctiv
e w
ith
15 G
W o
f win
d•
Line
arity
allo
ws
scal
e-up
of r
egul
atio
n pr
ocur
emen
t to
acco
mm
odat
e ye
ar-to
-yea
r win
d ad
ditio
ns•
Und
er-p
rocu
rem
ents
are
not
sub
stan
tially
mor
e se
vere
•Th
ere
may
be
impr
ovem
ents
whi
ch m
ight
be
mad
e to
the
met
hodo
logy
to re
duce
the
amou
nt o
f reg
ulat
ion
proc
ured
w
hile
mai
ntai
ning
acc
urac
y of
pro
cure
men
t
106
/
Pro
duct
ion
Sim
ulat
ion
107
/
In th
is n
ext s
et o
f slid
es, w
e w
ill s
how
:•
Hou
r-by
-hou
r pow
er p
rodu
ctio
n si
mul
atio
ns fo
r the
win
d sc
enar
ios,
usi
ng G
E M
ulti-
Are
a Pr
oduc
tion
Sim
ulat
ion
(MA
PS
) pro
gram
–U
nit c
omm
itmen
t–
Dis
patc
h•
Pro
gram
out
puts
–P
rodu
ctio
n co
sts
–S
pot p
rices
–S
pinn
ing
rese
rve
pric
es–
Ram
ping
cap
abili
ty a
nd ra
nge
–E
mis
sion
s
Issu
es:
•H
ow w
ind
affe
cts
unit
com
mitm
ent a
nd p
rodu
ctio
n•
Impa
ct o
n m
arke
t pric
es (e
nerg
y an
d an
cilla
ry s
ervi
ces)
108
/
Ene
rgy
Out
put
Com
mitm
ent B
ased
on
Sta
te-o
f-Art
Fore
cast
0
20,0
00
40,0
00
60,0
00
80,0
00
100,
000
120,
000
140,
000
160,
000
CC
GT
STC
OAL
ST
NG
WIN
D
Energy (GWh)
Zero
Win
d5
GW
Win
d10
GW
Win
d - C
ase
110
GW
Win
d - C
ase
215
GW
Win
d
Maj
or im
pact
is o
n co
mbi
ned
cycl
e un
it op
erat
ion,
co
nsis
tent
with
resu
lts o
bser
ved
in o
ther
stu
dies
109
/
Pea
k Lo
ad W
eek
(Aug
11-
18) -
Sta
te o
f the
Art
Fore
cast
0
1000
0
2000
0
3000
0
4000
0
5000
0
6000
0
7000
0
8000
0
18
1522
2936
4350
5764
7178
8592
9910
611
312
012
713
414
114
815
516
2
Hou
r
MW
HYDR
O
NUCL
EAR
STEA
M C
OAL
W
IND
COM
B. C
YCLE
ST
EAM
GAS
G
AS T
URBI
NE
0
1000
0
2000
0
3000
0
4000
0
5000
0
6000
0
7000
0
1
815
2229
3643
50
5764
7178
8592
99
106113
120127
134141
148
155162
Hou
r
MW
HYDR
O
NUCL
EAR
STEA
M C
OAL
W
IND
COM
B. C
YCLE
ST
EAM
GAS
G
AS T
URBI
NE
Zero
Win
d -D
ispa
tch
Zero
Win
d -C
omm
itmen
t
15 G
W W
ind
-Com
mitm
ent
15 G
W W
ind
-Dis
patc
h
0
1000
0
2000
0
3000
0
4000
0
5000
0
6000
0
7000
0
8000
0
18
1522
2936
4350
5764
7178
8592
9910
611
312
012
713
414
114
815
516
2
Hour
MW
0
1000
0
2000
0
3000
0
4000
0
5000
0
6000
0
7000
0
8000
0
18
1522
2936
4350
5764
7178
8592
9910
611
312
012
713
414
114
815
516
2
Hour
MW
HYD
RO
N
UC
LEA
R
STEA
M C
OA
L W
IND
C
OM
B. C
YCLE
ST
EAM
GA
S G
AS
TUR
BIN
E
110
/
0
5000
1000
0
1500
0
2000
0
2500
0
3000
0
3500
0
4000
0
4500
0
18
1522
2936
4350
5764
7178
8592
9910
611
312
012
713
414
114
815
516
2
Hou
r
MW
NU
CLE
AR
H
YDR
O
STEA
M C
OA
L W
IND
C
OM
B. C
YCLE
S
TEA
M G
AS
G
AS
TU
RB
INE
0
5000
1000
0
1500
0
2000
0
2500
0
3000
0
3500
0
4000
0
4500
0
5000
0
18
1522
2936
4350
5764
7178
8592
9910
611
312
012
713
414
114
815
516
2
Hou
r
MW
HYD
RO
N
UC
LEA
R
STE
AM
CO
AL
WIN
D
CO
MB
. CYC
LE
STE
AM
GA
S
GA
S T
UR
BIN
E
Zero
Win
d -D
ispa
tch
Zero
Win
d -C
omm
itmen
t
15 G
W W
ind
-Dis
patc
h
050
0010
000
1500
020
000
2500
030
000
3500
040
000
4500
050
000
18
1522
2936
4350
5764
7178
8592
9910
611
312
012
713
414
114
815
516
2
Hour
MW
050
0010
000
1500
020
000
2500
030
000
3500
040
000
4500
050
000
18
1522
2936
4350
5764
7178
8592
9910
611
312
012
713
414
114
815
516
2
Hour
MW
Pea
k W
ind
Wee
k (A
pril
2-9)
-S
tate
of t
he A
rt Fo
reca
st
15 G
W W
ind
-Com
mitm
ent
HYD
RO
N
UC
LEA
R
STEA
M C
OA
L W
IND
C
OM
B. C
YCLE
ST
EAM
GA
S G
AS
TUR
BIN
E
111
/
Pro
duct
ion
Cos
t Red
uctio
ns D
ue to
Win
d
0.00
10.0
0
20.0
0
30.0
0
40.0
0
50.0
0
60.0
0
5 G
W W
ind
10 G
W W
ind
- Cas
e 1
10 G
W W
ind
- Cas
e 2
15 G
W W
ind
Cost Savings ($/MWh)
Valu
e of
win
d de
crea
ses
slig
htly
with
incr
ease
d w
ind
pene
trat
ion
112
/
Tota
l Ann
ual E
mis
sion
s(S
tate
-of-A
rt W
ind
Fore
cast
Ass
umed
)
54,0
00
56,0
00
58,0
00
60,0
00
62,0
00
64,0
00
66,0
00
68,0
00
Zero
Win
d5
GW
Win
d10
GW
Win
d -
Cas
e 1
10 G
WW
ind
-C
ase
2
15 G
WW
ind
NO
x(T
ON
S)
160,
000,
000
165,
000,
000
170,
000,
000
175,
000,
000
180,
000,
000
185,
000,
000
190,
000,
000
195,
000,
000
200,
000,
000
205,
000,
000
Zero
Win
d5
GW
Win
d10
GW
Win
d -
Cas
e 1
10 G
WW
ind
-C
ase
2
15 G
WW
ind
CO
2 (T
ON
S)590,
000
600,
000
610,
000
620,
000
630,
000
640,
000
650,
000
660,
000
Zero
Win
d5
GW
Win
d10
GW
Win
d -
Case
1
10 G
WW
ind
-Ca
se 2
15 G
WW
ind
SO2
(TO
NS)
113
/
Ene
rgy
Spo
t Pric
es –
Ass
umes
Sta
te o
f the
Art
Fore
cast
020406080100
120
140
160
180
010
0020
0030
0040
0050
0060
0070
0080
0090
00
Hou
rs
Spot Price($/MWh)
No
Win
d5
GW
10 G
W -
Cas
e 1
10 G
W -
Cas
e 2
15 G
W
114
/
Impa
ct o
f Win
d Fo
reca
st o
n E
nerg
y P
rices
–15
GW
Win
d
020406080100
120
140
160
180
010
0020
0030
0040
0050
0060
0070
0080
00
Hour
Spot Price ($/MWh)
Zero
Win
dNo
For
ecas
tSt
udy
Year
For
ecas
tPe
rfect
For
ecas
t
Goo
d fo
reca
sts
min
imiz
e re
duct
ions
in s
pot
pric
es a
nd re
duce
ove
rall
ener
gy c
ost;
due
to le
ss o
ver-
com
mitm
ent
S-o-
A Fo
reca
st
115
/
In s
umm
ary:
•E
mis
sion
s an
d no
dal e
nerg
y pr
ices
dec
reas
e as
win
d pe
netra
tion
incr
ease
s
•V
alue
of w
ind
per M
Wh
decr
ease
s sl
ight
ly w
ith in
crea
sed
win
d pe
netra
tion
•B
ulk
of e
nerg
y di
spla
cem
ent i
s fro
m c
ombi
ned
cycl
e un
its
•La
ck o
f win
d fo
reca
st re
sults
in s
igni
fican
t ove
r com
mitm
ent
of u
nits
–de
pres
sing
nod
al p
rices
116
/
Ava
ilabl
e R
egul
atio
n R
ange
117
/
In th
is n
ext s
et o
f slid
es, w
e w
ill sh
ow:
•H
ow th
e ch
ange
s in
uni
t com
mitm
ent a
nd d
ispa
tch
affe
ct th
e ab
ility
to m
eet r
egul
atio
n re
quire
men
ts
with
incr
ease
d w
ind
pene
tratio
nK
ey is
sues
are
:•
Dis
plac
emen
t of c
onve
ntio
nal g
ener
atio
n•
Flex
ibili
ty o
f com
mitt
ed u
nits
118
/
Dow
n R
egul
atio
n R
esou
rces
B
ased
on
stat
e of
the
art f
orec
ast
0
200
400
600
800
1000
1200
1400
1600
18
1522
2936
4350
5764
7178
8592
9910
611
312
012
713
414
114
815
516
2H
our
MW/Min
GA
S TU
RBIN
E
STEA
M G
AS
COM
B. C
YCL
E
STEA
M C
OA
L
HYDR
O
0
500
1000
1500
2000
2500
3000
18
1522
2936
4350
5764
7178
8592
9910
611
312
012
713
414
114
815
516
2H
our
MW/Min
Gas
Tur
bine
Stea
m G
asCo
mbi
ned
Cycl
eSt
eam
Coa
lHy
dro
Zero
Win
d
0
500
1000
1500
2000
2500
3000
18
1522
2936
4350
5764
7178
8592
9910
611
312
012
713
414
114
815
516
2H
our
MW/Min
Gas
Tur
bine
Stea
m G
asCo
mbi
ned
Cycl
eSt
eam
Coa
lHy
dro
15 G
W W
ind
0
200
400
600
800
1000
1200
1400
1600
1800
18
1522
2936
4350
5764
7178
8592
9910
611
312
012
713
414
114
815
516
2H
our
MW/Min
GA
S TU
RBIN
EST
EAM
GA
SCO
MB.
CY
CLE
STEA
M C
OA
LHY
DRO
Zero
Win
d15
GW
Win
dM
in L
oad
Wee
k (M
arch
20-
27)
Peak
Loa
d W
eek
(Aug
ust 1
1-18
)
Hyd
roSt
eam
Coa
lC
ombi
ned
Cyc
leSt
eam
Gas
Gas
Tur
bine
119
/
Sys
tem
Reg
ulat
ion
Cap
acity
Load
Alo
neLo
ad –
5000
MW
Win
d
Load
–10
,000
MW
Win
d (1
)Lo
ad –
15,0
00 M
W W
ind
Ran
ge is
lim
ited
to th
e am
ount
whi
ch c
an b
e su
pplie
d in
five
min
utes
-150
00
-100
00
-500
00
5000
1000
0
1500
0
017
5235
0452
5670
0887
60
Hou
r
MW
5 x
Up R
amp
Up
Reg
(Pro
cure
d)D
own
Reg
(Pro
cure
d)5
x Do
wn
Ram
p
-150
00
-100
00
-500
00
5000
1000
0
1500
0
017
5235
0452
5670
0887
60
Hou
r
MW
5 x
Up R
amp
Up
Reg
(Pro
cure
d)D
own
Reg
(Pro
cure
d)5
x Do
wn
Ram
p
-150
00
-100
00
-500
00
5000
1000
0
1500
0
017
5235
0452
5670
0887
60
Hou
r
MW
5 x
Up R
amp
Up
Reg
(Pro
cure
d)D
own
Reg
(Pro
cure
d)5
x Do
wn
Ram
p
-150
00
-100
00
-500
00
5000
1000
0
1500
0
017
5235
0452
5670
0887
60
Hou
r
MW
5 x
Up
Ram
pUp
Reg
(Pro
cure
d)Do
wn
Reg
(Pro
cure
d)5
x D
own
Ram
p
120
/
Dow
n R
egul
atio
n R
ange
Def
icie
ncie
sD
own-
regu
latio
n re
quire
men
ts
incr
ease
slig
htly
.
Syst
em fl
exib
ility
is d
ecre
ased
due
to
redu
ced
net l
oad
Res
ult:
syst
em c
anno
t ac
com
mod
ate
dow
n-re
gula
tion
need
s w
ithou
t adj
ustin
g di
spat
ch
Trad
eoff
betw
een
cost
s of
adj
ustin
g di
spat
ch v
ersu
s cu
rtai
lmen
t or r
amp
limit
of w
ind
gene
rato
rs.
-600
0
-400
0
-200
00 500
550
600
650
700
750
800
Hou
r
MW
5 x
Dow
n R
amp
Dow
n R
eg (P
rocu
red)
316
157
1097
710
,000
(2)
712
202
1030
851
15,0
00
482
246
2709
1110
,000
(1)
00
00
5,00
0
00
00
0
Max
imum
Sho
rtfal
l (M
W)
Ave
rage
Def
icie
ncy
(MW
)To
tal M
Wh
Def
icie
ntH
ours
Def
icie
ntW
ind
(MW
)
121
/
Reg
ulat
ion
Ran
ge
•U
p-re
gula
tion
rang
e m
argi
n is
redu
ced,
but
rem
ains
am
ple
–A
ssum
ing
5-m
inut
e de
liver
y–
Mar
gin
coul
d be
less
if a
fast
er d
eliv
ery
is re
quire
d•
Dow
n-re
gula
tion
rang
e be
com
es a
n oc
casi
onal
issu
e fo
r >
5,00
0 M
W o
f win
d–
Com
mitt
ed c
onve
ntio
nal u
nits
are
pus
hed
tow
ard
thei
r min
imum
lo
ad le
vels
–R
elat
ivel
y fe
w h
ours
are
invo
lved
for w
ind
leve
ls in
vest
igat
ed•
Alte
rnat
ives
–C
onve
ntio
nal u
nits
can
be
de-c
omm
itted
to p
rovi
de ra
nge,
can
adve
rsel
y im
pact
eco
nom
ics
durin
g th
e ne
xt d
ay–
Allo
w w
ind
plan
ts to
pro
vide
dow
n-re
gula
tion
–A
pply
up-
ram
p lim
its o
n w
ind
gene
ratio
n–
Cur
tail
win
d ou
tput
•Fu
ture
ope
ratio
ns w
ill re
quire
incr
ease
d fle
xibi
lity
from
ba
lanc
e of
gen
erat
ion
122
/
Reg
ulat
ion
Ser
vice
Cos
ts
123
/
In th
is n
ext s
et o
f slid
es, w
e w
ill sh
ow:
•Th
e im
pact
of w
ind
on p
er-u
nit c
osts
of r
egul
atio
n se
rvic
es•
The
cost
s of
incr
ease
d re
gula
tion
serv
ices
to
acco
mm
odat
e w
ind
pene
tratio
n•
Em
phas
is o
n re
lativ
e m
etric
s
124
/
0102030405060708090100
010
0020
0030
0040
0050
0060
0070
0080
00Ho
urs
Cost of Spin ($/MWh)
Zero
Win
d5
GW
Win
d10
GW
Win
d - C
ase
110
GW
Win
d - C
ase
215
GW
Win
d
Stat
e of
Art
For
ecas
t
0102030405060708090100
010
0020
0030
0040
0050
0060
0070
0080
00Ho
urs
Cost of Spin ($/MWh)
Zero
Win
d5
GW
Win
d10
GW
Win
d - C
ase
110
GW
Win
d - C
ase
215
GW
Win
d
No
Fore
cast
0102030405060708090100
010
0020
0030
0040
0050
0060
0070
0080
00Ho
urs
Cost of Spin ($/MWh)Ze
ro W
ind
5 G
W W
ind
10 G
W W
ind
- Cas
e 1
10 G
W W
ind
- Cas
e 2
15 G
W W
ind
Perf
ect F
orec
ast
Spi
n C
ost f
or V
ario
us
Win
d P
enet
ratio
ns
125
/
Reg
ulat
ion
Cos
t Ass
umpt
ions
•R
EG
cos
t is
the
grea
ter o
f $5/
MW
hor
the
cost
of
spin
ning
rese
rve
•C
ost o
f win
d cu
rtailm
ent a
dded
whe
n –R
EG
exc
eeds
av
aila
ble
rang
e (s
pot p
rice)
•R
esul
ts m
ost u
sefu
l whe
n co
nsid
ered
on
a re
lativ
e ba
sis
126
/
Cos
t of M
eetin
g R
egul
atio
n S
ervi
ce R
equi
rem
ents
–S
-o-A
For
ecas
t
•R
educ
tion
of n
et lo
ad s
light
ly
decr
ease
s pe
r MW
hco
st o
f +R
EG
and
–R
EG
, up
thro
ugh
10,0
00 M
W s
cena
rios
•E
xces
s un
it co
mm
itmen
ts d
ue to
lo
ad fo
reca
st e
rror
s, a
nd re
duce
d ne
t loa
d sh
arpl
y dr
ops
regu
latio
n co
st a
t 15,
000
MW
0
2,00
0,00
0
4,00
0,00
0
6,00
0,00
0
050
0010
000
1500
0W
ind
Cap
acity
(MW
)
Procured REG MWh
Tota
l+R
EG-R
EG
75%
80%
85%
90%
95%
100%
105%
None 50
00 10,00
0 (1) 10
,000 (
2)15
,000
Win
d C
apac
ity (M
W)
Relative Cost of REG per MWh Procured
+REG
-REG
0%20%
40%
60%
80%
100%
120%
Non
e 5
000
10,0
00(1
)10
,000
(2)
15,0
00
Win
d Sc
enar
io
Relative Cost of Procured REG
Tota
l+R
EG-R
EG
127
/
Cos
t of M
eetin
g R
egul
atio
n S
ervi
ce R
equi
rem
ents
–P
erfe
ct F
orec
ast
•R
educ
ed u
nit o
ver-
com
mitm
ent
allo
ws
unit
cost
s of
regu
latio
n to
de
crea
se g
radu
ally
as
net l
oad
is
redu
ced
by in
crea
sed
win
d•
Tota
l cos
t of +
/-R
EG
incr
ease
s at
a m
uch
low
er ra
te th
an li
near
w
ith re
spec
t to
win
d ca
paci
ty
0
2,00
0,00
0
4,00
0,00
0
6,00
0,00
0
050
0010
000
1500
0W
ind
Cap
acity
(MW
)
Procured REG MWh
Tota
l+R
EG-R
EG
75%
80%
85%
90%
95%
100%
105%
None 50
00 10,00
0 (1) 10
,000 (
2)15
,000
Win
d C
apac
ity (M
W)
Relative Cost of REG per MWh Procured
+REG
-REG
0%20%
40%
60%
80%
100%
120%
Non
e 5
000
10,0
00(1
)10
,000
(2)
15,0
00
Win
d Sc
enar
io
Relative Cost of Procured REG
Tota
l+R
EG-R
EG
128
/
Reg
ulat
ion
Cos
ts S
umm
ary
•P
er-u
nit c
osts
of r
egul
atio
n ar
e hi
ghly
dep
ende
nt o
n im
pact
s of
w
ind
on d
ispa
tch
•Im
perfe
ct w
ind
fore
cast
lead
s to
un
it ex
cess
uni
t com
mitm
ent,
redu
cing
regu
latio
n co
sts
•R
esul
ts a
re v
olat
ile, m
akeu
p of
fu
ture
gen
erat
ion
portf
olio
is c
ritic
al
$0.0
7636
,180
,453
$143
.05
$72.
49$6
9.36
10,0
00 (2
)
$0.1
0737
,037
,236
$142
.30
$72.
93$7
0.12
10,0
00 (1
)
-$0.
180
53,9
33,3
79$1
29.3
7$6
7.94
$61.
4415
,000
$0.1
7917
,940
,311
$139
.09
$72.
76$6
9.54
5,00
0
$0.1
4453
,933
,379
$141
.85
$74.
83$7
2.01
15,0
00
$0.2
0036
,180
,453
$146
.33
$76.
21$7
0.12
10,0
00 (2
)
$0.2
7737
,037
,236
$149
.35
$78.
14$7
1.22
10,0
00 (1
)
$0.1
1217
,940
,311
$141
.11
$73.
21$6
7.90
5,00
0
0$1
39.0
9$7
2.21
$66.
880
Inc.
Cos
t of
Reg
ulat
ion
($/M
Wh)
Tota
l Win
d G
ener
atio
n(M
Wh)
Tota
l Reg
. C
ost
($M
M)
Reg
-Dow
nC
ost
($M
M)
Reg
-Up
Cos
t ($
MM
)
Win
d C
apac
ity(M
W)
Sta
te-o
f-A
rt W
ind
Fore
cast
Per
fect
W
ind
Fore
cast
-$0.
30
-$0.
20
-$0.
10
$0.0
0
$0.1
0
$0.2
0
$0.3
0
500
010
,000
(1)
10,0
00 (2
)15
,000
Win
d Sc
enar
io (M
W)
Incremental Cost of REG ($/MWh)(MWh of Total Wind Production)
S-o-
A Fo
reca
stPe
rfect
For
ecas
t
129
/
Fore
cast
Err
or A
naly
sis
Impa
ct o
n N
on-S
pinn
ing
Res
erve
s
130
/
Pre
dict
abili
ty A
naly
sis
131
/
Day
-ahe
ad p
redi
ctab
ility
of n
et lo
ad is
im
porta
nt to
uni
t com
mitm
ent;
inac
cura
cies
in
crea
se o
pera
ting
cost
s an
d m
ay re
quire
gr
eate
r A/S
pro
cure
men
t.Th
e ne
xt s
lides
ana
lyze
net
load
pre
dict
abili
ty
132
/
Tim
e of
Yea
r Pre
dict
abili
ty A
naly
sis
133
/
Load
Yea
rly A
vera
ge P
rofil
e an
d La
rges
t For
ecas
t Err
ors
Stu
dy Y
ear L
oad
with
150
00 M
W o
f Win
d
-180
00
-120
00
-600
00
6000
1200
0
1800
0
2400
0
3000
0
3600
0
4200
0
4800
0
5400
0
Actual and Day-Ahead Load (MW)
-900
0
-600
0
-300
0
03000
6000
9000
1200
0
1500
0
1800
0
2100
0
2400
0
2700
0
Max/Min Forecast Error (MW)
Load
Act
ual
Load
For
ecas
tM
ax P
os F
orec
ast E
rror
Max
Neg
For
ecas
t Erro
r
Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Sep
Oct
Nov
Dec
Win
ter
Spr
ing
Sum
mer
Fall
May
20t
h : La
rges
t Neg
Lo
ad F
orec
ast E
rror
Aug
28th
: Lar
gest
Pos
Lo
ad F
orec
ast E
rror
Mar
ch 2
7th
Min
Loa
d D
ay
Augu
st 1
7th
Peak
Loa
d D
ay
Max
L-W
Err
or =
102
94 M
W (A
ug 2
8th)
MA
E =
129
6M
W (3
.5%
of A
vera
ge)
RM
SE
= 1
792
MW
(4.9
% o
f Ave
rage
)S
igm
a =
1755
(4.8
% o
f Ave
rage
)
Gre
ater
tend
ency
to o
ver-
fore
cast
load
dur
ing
the
sum
mer
mon
ths
134
/
Net
Loa
d Y
early
Ave
rage
Pro
file
and
Larg
est F
orec
ast E
rror
sS
tudy
Yea
r Loa
d w
ith 1
5000
MW
of W
ind
-180
00
-120
00
-600
00
6000
1200
0
1800
0
2400
0
3000
0
3600
0
4200
0
4800
0
5400
0
Actual and Day-Ahead Load-Wind (MW)
-900
0
-600
0
-300
0
03000
6000
9000
1200
0
1500
0
1800
0
2100
0
2400
0
2700
0
Max/Min Forecast Error (MW)
Load
-Win
d Ac
tual
Load
-Win
d Fo
reca
stM
ax P
os F
orec
ast E
rror
Max
Neg
For
ecas
t Erro
r
Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Sep
Oct
Nov
Dec
Win
ter
Spr
ing
Sum
mer
Fall
Mar
11t
h : La
rges
t Neg
L-
W F
orec
ast E
rror
Aug
28th
: Lar
gest
Pos
L-
W F
orec
ast E
rror
Mar
ch 2
7th
Min
Net
Loa
d D
ay
July
17t
hPe
ak
Net
Loa
d D
ay
Max
L-W
Err
or =
967
5 M
W (A
ug 2
8th)
MA
E =
169
8M
W (5
.5%
of A
vera
ge)
RM
SE
= 2
199
MW
(7.2
% o
f Ave
rage
)S
igm
a =
2149
(7.0
% o
f Ave
rage
)
Win
d ge
nera
lly in
crea
ses
net-l
oad
fore
cast
err
ors
in W
inte
r and
Spr
ing
mor
e th
an S
umm
er
135
/
Net
Loa
d an
d W
ind
Day
-Ahe
ad P
redi
ctab
ility
–S
umm
ary
(
Stu
dy Y
ear D
ata)
5,00
0 M
W
10,0
00 M
W
1
5,00
0 M
W
0
300
600
900
1200
1500
1800
Error (MW)
20304050607080
% Error
MAE
(MW
)RM
SE (M
W)
%M
AE%
RMSE
2149
(7.0
)
1887
(5.8
)
1928
(5.9
)
1762
(5.1
)
1755
(4
.8)
Std
Dev
MW
(%)
1698
(5.5
)
1467
(4.5
)
1505
(4.6
)
1338
(3.8
)
1296
(3.5
)
MA
E*
MW
(%)
9765
9786
9763
9951
1029
4
Max
E
rror
(MW
)
1936
(5.9
)Lo
ad w
/ 10,
000
MW
W
ind
(2)
1792
(4.9
)B
ase
Cas
e: L
oad
w/
no W
ind
1805
(5.2
)Lo
ad w
/ 500
0 M
W
Win
d
2199
(7.2
)
1974
(6.0
)
RM
SE
**M
W(%
)
Load
w/ 1
5,00
0 M
W
Win
d
Load
w/ 1
0,00
0 M
W
Win
d (1
)Cas
e
* M
ean
abso
lute
erro
r **
Roo
t mea
n sq
uare
err
or –
mor
e af
fect
ed b
y la
rge
devi
atio
ns
-592
116
14(2
6.3)
1294
(21.
1)16
11(2
6.2)
15,0
00 M
W W
ind
-407
810
96(2
6.6)
876
(21.
3)10
93(2
6.5)
10,0
00 M
W W
ind
(2)
-426
411
69(2
7.7)
935
(22.
2)11
67(2
7.7)
10,0
00 M
W W
ind
(1)
-252
963
9(3
1.3)
511
(25.
0)63
8(3
1.2)
5000
MW
Win
d
Erro
r = fo
reca
st –
actu
al
500
1000
1500
2000
2500
Error (MW)
3%6%9%12%
15%
% Error
MAE
(MW
)RM
SE (M
W)
%M
AE%
RMSE
Load
L
-5,0
00 M
W
L-10
,000
MW
L-15
,000
MW
Win
d ab
solu
te e
rror
(M
W) i
ncre
ases
slo
wer
th
an a
vera
ge o
utpu
t
Abs
olut
e er
ror (
MW
) an
d pe
rcen
t err
or
incr
ease
line
arly
Net
Loa
d
Win
d
NB
: Per
cent
err
ors
base
d on
ave
rage
out
put
136
/
Hou
rly W
ind
Pre
dict
abili
ty (F
orec
ast E
rror
s*)
(Stu
dy Y
ear D
ata)
0
200
400
600
800
1000
1200
1400
1600
1800
< -4500-4500 – -4200-4200 – -3900-3900 – -3600-3600 – -3300-3300 – -3000-3000 – -2700-2700 – -2400-2400 – -2100-2100 – -1800-1800 – -1500-1500 – -1200-1200 – -900-900 – -600-600 – -300-300 – 00 – 300300 – 600600 – 900900 – 12001200 – 15001500 – 18001800 – 21002100 – 24002400 – 27002700 – 30003000 – 33003300 – 36003600 – 39003900 – 42004200 – 4500> 4500
MW
Hours
5000
MW
Win
d10
000
MW
Win
d (1
)10
000
MW
Win
d (2
)15
000
MW
Win
d
Win
d fo
reca
st e
rror
in
crea
ses
with
win
d,
skew
ed to
the
left
…
tend
ency
to u
nder
-fo
reca
st w
ind
Ext
rem
e Fo
reca
st E
rrors
* Erro
r = fo
reca
st –
actu
al
Ove
r-C
omm
itmen
tU
nder
-C
omm
itmen
t
910
/ 364
296
/ 19
384
/ 41
8 / 0
>±
2300
MW
(−/+
)
67 /
00
/ 00
/ 00
/ 0>
±46
00 M
W(−
/+)
43 /
048
/ 0
38 /
033
/ 0
>µ±
3σ (
−/+)
121
/ 1
10,0
00 M
W
Win
d (2
)
125
/ 2
10,0
00 M
W
Win
d (1
)
114
/ 110
7 / 9
>µ±
2.5σ
(−/
+)
5000
MW
W
ind
15,0
00 M
W
Win
d
137
/
0
100
200
300
400
500
600
700
800
900
1000
1100
1200
< -6000-6000 – -5600-5600 – -5200-5200 – -4800-4800 – -4400-4400 – -4000-4000 – -3600-3600 – -3200-3200 – -2800-2800 – -2400-2400 – -2000-2000 – -1600-1600 – -1200-1200 – -800-800 – -400-400 – 00 – 400400 – 800800 – 12001200 – 16001600 – 20002000 – 24002400 – 28002800 – 32003200 – 36003600 – 40004000 – 44004400 – 48004800 – 52005200 – 56005600 – 6000> 6000
MW
Hours
Load
-alo
neLo
ad-5
000
MW
Load
-150
00 M
W
Hou
rly L
oad-
Win
d P
redi
ctab
ility
(For
ecas
t Err
ors*
)
(Stu
dy Y
ear D
ata)
Win
d ad
ds to
ove
rall
net l
oad
fore
cast
err
or a
nd in
crea
ses
num
ber o
f ext
rem
e de
viat
ions
… te
nden
cy to
ov
er-fo
reca
st n
et lo
ad
* Erro
r = fo
reca
st –
actu
al
Und
er-
Com
mitm
ent
Ove
r C
omm
itmen
t
731
/ 159
154
7 / 1
357
413
/ 104
8>
±23
00 M
W(−
/+)
51 /
217
17 /
74
67 /
152
W/ 5
000
MW
Win
dσ
=17
62
Usi
ng l
oad
σ
17 /
77
66 /
160
51 /
129
10 /
4315
/ 95
>µ±
3σ (−
/+)
132
/ 271
51 /
111
64 /
185
>µ±
2.5σ
(−/+
)
26 /
186
Load
-alo
ne
σ =
1755
>±
4600
MW
(−/+
)72
/ 31
6
W/ 1
5000
MW
Win
dσ
=21
49
U
sing
loa
d σ
Ext
rem
e Fo
reca
st E
rrors
138
/
-600
0
-400
0
-200
00
2000
4000
6000
-800
0-4
000
040
0080
0012
000
Load
For
ecas
t Err
or
Wind Forecast Error
Win
ter
Sprin
gSu
mm
erFa
ll
Cor
rela
tion
of L
oad
and
Win
d Fo
reca
st E
rror
s B
y S
easo
n (S
tudy
Yea
r Loa
d an
d 15
000
MW
of W
ind)
1029
4 M
W-6
291
MW
R2
= .0
34
Ove
r-co
mm
itmen
tU
nder
-co
mm
itmen
t
Und
er-
com
mitm
ent
Ove
r-co
mm
itmen
t
Incr
ease
L-W
ov
er-fo
reca
st
Incr
ease
L-W
un
der-
fore
cast
Load
and
Win
d er
rors
offs
et
Load
and
Win
d er
rors
offs
et
Q1
Q2
Q3
Q4
Q3
139
/
Cor
rela
tion
of L
oad
and
Win
d Fo
reca
st E
rror
s B
y S
easo
n (S
tudy
Yea
r Loa
d W
/ 150
00 M
W)
-600
0
-400
0
-200
00
2000
4000
6000
-800
0-4
000
040
0080
0012
000
Load
Err
or
Wind Error
Win
ter
-600
0
-400
0
-200
00
2000
4000
6000
-800
0-4
000
040
0080
0012
000
Load
Err
or
Wind Error
Sprin
g
-600
0
-400
0
-200
00
2000
4000
6000
-800
0-4
000
040
0080
0012
000
Load
Err
or
Wind Error
Sum
mer
-600
0
-400
0
-200
00
2000
4000
6000
-800
0-4
000
040
0080
0012
000
Load
Err
or
Wind Error
Fall
Ove
r-co
mm
itmen
tU
nder
-co
mm
itmen
t
Und
er-
com
mitm
ent
Ove
r-co
mm
itmen
t
Incr
ease
L-W
O
ver-
fore
cast
Incr
ease
L-W
U
nder
-fore
cast
Load
and
Win
d er
rors
offs
et
Load
and
Win
d er
rors
offs
et
Ris
k of
sim
ulta
neou
sun
der-
com
mitm
ent
erro
r is
very
sm
all
Q1
Q2
Q3
Q4
140
/
12
34
56
78
910
1112
1314
1516
1718
1920
2122
2324
Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Sep
Oct
Nov
Dec
Hou
r of D
ay
Month of Year
-200
0-0
-400
0--2
000
-600
0--4
000
-800
0--6
000
Tim
ing
of N
egat
ive
Load
For
ecas
t Err
ors
(Und
er-C
omm
itmen
t)
(S
tudy
Yea
r) Larg
est l
oad
unde
r-fo
reca
sts
typi
cally
occ
ur in
th
e af
tern
oon
and
early
eve
ning
dur
ing
Win
ter
and
early
Spr
ing
-629
1 M
W
-627
2 M
W
141
/
Tim
ing
of N
egat
ive
Net
-Loa
d (U
nder
-Com
mitm
ent)
Fore
cast
Erro
rs(S
tudy
Yea
r Loa
d w
ith 1
5000
MW
of W
ind)
12
34
56
78
910
1112
1314
1516
1718
1920
2122
2324
Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Sep
Oct
Nov
Dec
Hou
r of D
ay-2
000-
0-4
000-
-200
0-6
000-
-400
0-8
000-
-600
0
Larg
e ne
t-loa
d un
der-
fore
cast
s m
uch
mor
e sp
read
with
ove
r the
yea
r due
to s
prea
d in
w
ind
fore
cast
err
ors.
Ext
rem
e er
rors
tend
to
occu
r in
Win
ter a
nd e
arly
Spr
ing.
-778
1 M
W
-732
2 M
W
-609
9 M
W
-608
3 M
W
Month of Year
142
/
Incr
emen
tal U
nder
-For
ecas
t Err
ors
Due
to W
ind
(S
tudy
Yea
r Loa
d w
ith 1
5000
MW
of W
ind)
12
34
56
78
910
1112
1314
1516
1718
1920
2122
2324
Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Sep
Oct
Nov
Dec
Hou
r of D
ay
Month of Year
1000
-250
0-5
00-1
000
-200
0--5
00-3
500-
-200
0
1500
0 M
W o
f win
d te
nds
to c
ause
a
mod
erat
ely
wid
espr
ead
incr
ease
in fo
reca
st
unce
rtain
ty
-302
8 M
W
-296
5 M
W
-260
5 M
W
-222
9 M
W
-233
8 M
W
-246
3 M
W
-263
1 M
W
143
/
Janu
ary
Hou
rly L
oad
and
Net
Loa
d Fo
reca
st E
rror
s
(Stu
dy Y
ear L
oad
with
150
00 M
W o
f Win
d)
(Avg
. +/-
sigm
a, M
inim
um, M
axim
um)
Hou
r of D
ay
Forecast Errors (MW)
Total Load (MW)
01
23
45
67
89
1011
1213
1415
1617
1819
2021
2223
2425
04500
9000
1350
0
1800
0
2250
0
2700
0
3150
0
3600
0
-800
0
-600
0
-400
0
-200
00
2000
4000
6000
8000
-800
0
-600
0
-400
0
-200
00
2000
4000
6000
8000
Load
Erro
rsLo
ad-W
ind
Erro
rsTo
tal L
oad
Load
-Win
d
Ris
k th
at w
ind
curta
ilmen
tco
uld
be in
frequ
ently
nee
ded
Tend
s to
be
avai
labl
e re
sour
ces
144
/
July
Hou
rly L
oad
and
Net
Loa
d Fo
reca
st E
rror
s (S
tudy
Yea
r Loa
d w
ith 1
5000
MW
of W
ind)
(Avg
. +/-
sigm
a, M
inim
um, M
axim
um) Hou
r of D
ay
Forecast Errors (MW)
Total Load (MW)
-800
0
-600
0
-400
0
-200
00
2000
4000
6000
8000
01
23
45
67
89
1011
1213
1415
1617
1819
2021
2223
2425
07500
1500
0
2250
0
3000
0
3750
0
4500
0
5250
0
6000
0
-800
0
-600
0
-400
0
-200
00
2000
4000
6000
8000
Load
Erro
rsLo
ad-W
ind
Erro
rsTo
tal L
oad
Load
-Win
d
145
/
Obs
erva
tions
and
Con
clus
ions
•R
isk
of u
nder
-com
mitm
ent t
ends
to o
ccur
off-
peak
whe
n im
pact
is lo
w–
Und
er-c
omm
itmen
t agg
rava
ted
by u
sing
a h
ighe
r co
nfid
ence
leve
l win
d fo
reca
st•
Dur
ing
sum
mer
pea
k ho
urs,
win
d fo
reca
st e
rror
tend
s to
pa
rtial
ly c
ance
l app
aren
t bia
s in
mea
n lo
ad fo
reca
st to
war
ds
over
-com
mitm
ent
•In
crea
sed
win
d pe
netra
tion
does
not
cre
ate
an o
bvio
us
requ
irem
ent f
or a
cros
s-th
e-bo
ard
non-
spin
rese
rve
requ
irem
ents
incr
ease
–P
erio
ds w
here
unc
erta
inty
is h
igh
and
reso
urce
s ar
e tig
ht
may
requ
ire a
dditi
on o
f NS
RS
–C
onsi
der a
long
er-te
rm N
SR
S s
ervi
ce
146
/
•A
dditi
on o
f win
d re
quire
s a
mod
erat
e in
crea
se o
f anc
illar
y se
rvic
e re
quire
men
ts•
At c
erta
in lo
w-lo
ad, h
igh-
win
d co
nditi
ons,
pro
vidi
ng d
own-
regu
latio
n ca
n be
a c
halle
nge
•P
rese
nt E
RC
OT
proc
urem
ent m
etho
dolo
gies
:–
Reg
ulat
ion
algo
rithm
ade
quat
e, s
ome
incr
emen
tal i
mpr
ovem
ents
are
poss
ible
–R
espo
nsiv
e re
serv
e pr
oced
ure
adeq
uate
, may
nee
d to
acc
ount
fo
r pre
dict
ed w
ind
risk
perio
ds–
Non
-spi
n ca
n be
a p
refe
rabl
e al
tern
ativ
e to
car
ryin
g la
rge
amou
nts
of R
RS
dur
ing
high
-ris
k pe
riods
•In
crea
sed
regu
latio
n se
rvic
es c
reat
e a
smal
l inc
rem
ent (
1%) i
n co
st
rela
tive
to v
alue
ofM
Wh
supp
lied
by w
ind
Ove
rall
Con
clus
ions
