POWER October 2012 - 24

4. Balancing act. This is the expected typical April load profile for CAISO in 2020, the year when California's 33% renewable portfolio standard
becomes effective. When the sun shines during the day, and the wind blows in the afternoon, conventional thermal resources have to be
ramped down. But when demand spikes in the morning and early evening, conventional resources have to be dispatched (the red line) to supply
the needed power. Source: CAISO
Load
45,000
40,000
35,000
30,000
25,000
20,000
15,000
10,000
5,000
Net load
Wind
Solar
14,000
12,000
10,000
8,000
6,000
4,000
2,000
To make this work requires a full comple5.
Variable resource. Typical power production data illustrates the wide variability of wind
generation in CAISO. Source: CAISO
6,000
5,000
4,000
3,000
2,000
1,000
Average
ment of fast-start gas turbines throughout
the state ready to come online at a moment's
notice. This is why roughly half
of the LMS100s GE has sold to date have
been installed in California (including, for
example, the Panoche Energy Center in
Firebaugh, Calif., which is profiled in the
September 2011 issue, available at www
.powermag.com).
" The nature of this fluctuating renew1
2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24
Hour
smooth curve, on an hourly and daily
basis, it is quite variable.
Solar is similarly unpredictable. On a
day-to-day basis, you may know that it
will be cloudy or sunny, but each passing
cloud drops the output on a photovoltaic
array. " It is difficult to predict what wind
is going to do from one day to the next, "
said Clyde Loutan, senior advisor for the
market and infrastructure development
at CAISO. " The big challenge is balancing
wind and solar in real time due to subhourly
variations. "
He said that CAISO can lose 500 MW
in 5 minutes due to wind drop or cloud
cover. To improve the ability to rapidly
24
respond to these changes, CAISO has
set up a new control center with a dedicated
renewables dispatch desk, which is
manned 24/7 in an attempt to stay ahead
of changes in wind and solar output.
" We have a lot of high-tech tools in the
data center such as geospatial map tech, so
we can see changes in weather conditions,
wind resource areas, and solar resource areas
and see output in real time, " said McCorkle.
" The visuals will show changes in how much
of installed capacity is actually producing
so our renewable dispatchers can try to put
a megawatt number on either the increase
or decrease and we can fire up the gas-fired
generators to compensate for that. "
www.powermag.com
able power requires other generation to
respond quickly to match the total load
demand and maintain grid stability, " said
GE LMS100 Product Manager Phil Tinne.
" The LMS100 machine is ideally suited to
this task: It can ramp power at 50 MW/
min over a very wide load range while
staying in emissions compliance [with
exhaust system treatment for California's
strict standards]. "
Renewables and Transmission
In addition to variability, the other problem
posed by renewables is that these
generation sources are often sited far
away from the load, increasing the need
to provide more reactive power.
" When you go out into the desert and
mountains to produce solar and wind energy,
this power has to travel great distances
on the transmission lines, which
in many cases don't even exist yet, " said
Ken Buttke, Jr. a power generation manufacturers'
representative with South Port
Equipment in Agoura Hills, Calif. " As you
POWER | October 2012
MW
MW
0:00
0:39
1:18
1:57
2:36
3:15
3:54
4:33
5:12
5:51
6:30
7:09
7:48
8:27
9:06
9:45
10:24
11:03
11:42
12:21
13:00
13:39
14:18
14:57
15:36
16:15
16:54
17:33
18:12
18:51
19:30
20:09
20:48
21:27
22:06
22:45
23:24
Wind and solar MW

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POWER October 2012

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