IEEE Power & Energy Magazine - November/December 2015 - 83

energy to provide system support. Wind curtailment is
achieved by either automated market-based mechanisms,
such as the MISO dispatchable intermittent resource (DIR)
economic dispatch or through manual directives by the system operator. Usually the most expensive plant is curtailed
first to alleviate system congestion or maintain system balance. The economic compensation provided to the wind
power plant varies and depends on the specifics of the power
contract. Output from individual turbines can be reduced
in seconds to provide downward reserves and ramping support. Output from curtailed wind turbines can be increased
quickly, on the order of seconds to tens of seconds, to provide frequency, upward reserve, and ramping services.
Curtailment from PVs is achieved by controlling inverter
output, and therefore it acts on very short timescales of fractions of seconds. This turns wind and PVs into dispatchable
resources, but it is at the economic cost of reduced energy
output. Therefore, the economic choice to curtail VG at any
given moment reflects the trade-off between the instantaneous value of the energy produced and the value of upward
reserves provided. This economic trade-off is further complicated for wind (in the United States) for projects utilizing
production-based subsidies. However, some positive feedback may exist. For example, thermal generators that stay
online to provide upward reserves and subsequently force
wind to curtail could instead be decommitted if the curtailed
wind provides the upward reserves.

VG Can Be Economically Dispatched
There can be times when the system is constrained with too
much generation and not enough demand and/or transmission
to move the energy. Managing this type of overgeneration

condition is most effective if the solution is incorporated
directly into the economic dispatch process, which (under normal conditions) requires no direct operator intervention and
can be done very quickly and cost effectively. MISO manages
more than 14 GW of wind generation in its market footprint.
The continued growth of wind generation, especially in the
western areas of its territory, has created local transmission
congestion issues during certain periods that were traditionally managed by manual curtailments of specific wind generation facilities. In 2011, MISO implemented the DIR protocol,
which effectively places wind power plants on AGC under
control of the MISO real-time market systems. This resulted
is an overall reduction of curtailed renewable energy delivery
along with a much higher level of operational efficiency and
transparency. Figure 3 shows the monthly downward dispatch
of energy as a percent of the economic maximum. According
to MISO, approximately 95% of wind energy's potential can
be captured through economic dispatch. All new wind generation facilities in MISO must register as DIRs, and more
than 80% of wind generation in MISO is dispatchable.

VG Can Contribute to
Operational Security
As the instantaneous penetration of VG resources increases,
there is greater interest in wind's potential impacts on maintaining the operational stability and security of the bulk
power system during and after major disturbances. Although
this has not been studied as extensively as balancing issues
or widely incorporated into system operation, there is
increased understanding that VG can provide frequency,
inertia, and voltage control capabilities that have been traditionally provided by synchronous generators.

3,500

20
DIR Dispatched Energy (Left Axis)
DIR Dispatch Below Economic Maximum (Left Axis)
% of DIR Dispatched Down (Right Axis)

18
16

GWh

2,500

14
12

2,000

10
1,500

8
6

1,000

Dispatch Down (%)

3,000

4
500

2
Apr. 2013

Mar. 2013

Jan. 2013

Feb. 2013

Dec. 2012

Oct. 2012

Nov. 2012

Sep. 2012

July 2012

Aug. 2012

May 2012

June 2012

Apr. 2012

Mar. 2012

Jan. 2012

Feb. 2012

Dec. 2011

Oct. 2011

Nov. 2011

Sep. 2011

July 2011

Aug. 2011

0
June 2011

0

figure 3. Wind power plant dispatch in MISO with DIR protocol.
november/december 2015

ieee power & energy magazine

83



Table of Contents for the Digital Edition of IEEE Power & Energy Magazine - November/December 2015

IEEE Power & Energy Magazine - November/December 2015 - Cover1
IEEE Power & Energy Magazine - November/December 2015 - Cover2
IEEE Power & Energy Magazine - November/December 2015 - 1
IEEE Power & Energy Magazine - November/December 2015 - 2
IEEE Power & Energy Magazine - November/December 2015 - 3
IEEE Power & Energy Magazine - November/December 2015 - 4
IEEE Power & Energy Magazine - November/December 2015 - 5
IEEE Power & Energy Magazine - November/December 2015 - 6
IEEE Power & Energy Magazine - November/December 2015 - 7
IEEE Power & Energy Magazine - November/December 2015 - 8
IEEE Power & Energy Magazine - November/December 2015 - 9
IEEE Power & Energy Magazine - November/December 2015 - 10
IEEE Power & Energy Magazine - November/December 2015 - 11
IEEE Power & Energy Magazine - November/December 2015 - 12
IEEE Power & Energy Magazine - November/December 2015 - 13
IEEE Power & Energy Magazine - November/December 2015 - 14
IEEE Power & Energy Magazine - November/December 2015 - 15
IEEE Power & Energy Magazine - November/December 2015 - 16
IEEE Power & Energy Magazine - November/December 2015 - 17
IEEE Power & Energy Magazine - November/December 2015 - 18
IEEE Power & Energy Magazine - November/December 2015 - 19
IEEE Power & Energy Magazine - November/December 2015 - 20
IEEE Power & Energy Magazine - November/December 2015 - 21
IEEE Power & Energy Magazine - November/December 2015 - 22
IEEE Power & Energy Magazine - November/December 2015 - 23
IEEE Power & Energy Magazine - November/December 2015 - 24
IEEE Power & Energy Magazine - November/December 2015 - 25
IEEE Power & Energy Magazine - November/December 2015 - 26
IEEE Power & Energy Magazine - November/December 2015 - 27
IEEE Power & Energy Magazine - November/December 2015 - 28
IEEE Power & Energy Magazine - November/December 2015 - 29
IEEE Power & Energy Magazine - November/December 2015 - 30
IEEE Power & Energy Magazine - November/December 2015 - 31
IEEE Power & Energy Magazine - November/December 2015 - 32
IEEE Power & Energy Magazine - November/December 2015 - 33
IEEE Power & Energy Magazine - November/December 2015 - 34
IEEE Power & Energy Magazine - November/December 2015 - 35
IEEE Power & Energy Magazine - November/December 2015 - 36
IEEE Power & Energy Magazine - November/December 2015 - 37
IEEE Power & Energy Magazine - November/December 2015 - 38
IEEE Power & Energy Magazine - November/December 2015 - 39
IEEE Power & Energy Magazine - November/December 2015 - 40
IEEE Power & Energy Magazine - November/December 2015 - 41
IEEE Power & Energy Magazine - November/December 2015 - 42
IEEE Power & Energy Magazine - November/December 2015 - 43
IEEE Power & Energy Magazine - November/December 2015 - 44
IEEE Power & Energy Magazine - November/December 2015 - 45
IEEE Power & Energy Magazine - November/December 2015 - 46
IEEE Power & Energy Magazine - November/December 2015 - 47
IEEE Power & Energy Magazine - November/December 2015 - 48
IEEE Power & Energy Magazine - November/December 2015 - 49
IEEE Power & Energy Magazine - November/December 2015 - 50
IEEE Power & Energy Magazine - November/December 2015 - 51
IEEE Power & Energy Magazine - November/December 2015 - 52
IEEE Power & Energy Magazine - November/December 2015 - 53
IEEE Power & Energy Magazine - November/December 2015 - 54
IEEE Power & Energy Magazine - November/December 2015 - 55
IEEE Power & Energy Magazine - November/December 2015 - 56
IEEE Power & Energy Magazine - November/December 2015 - 57
IEEE Power & Energy Magazine - November/December 2015 - 58
IEEE Power & Energy Magazine - November/December 2015 - 59
IEEE Power & Energy Magazine - November/December 2015 - 60
IEEE Power & Energy Magazine - November/December 2015 - 61
IEEE Power & Energy Magazine - November/December 2015 - 62
IEEE Power & Energy Magazine - November/December 2015 - 63
IEEE Power & Energy Magazine - November/December 2015 - 64
IEEE Power & Energy Magazine - November/December 2015 - 65
IEEE Power & Energy Magazine - November/December 2015 - 66
IEEE Power & Energy Magazine - November/December 2015 - 67
IEEE Power & Energy Magazine - November/December 2015 - 68
IEEE Power & Energy Magazine - November/December 2015 - 69
IEEE Power & Energy Magazine - November/December 2015 - 70
IEEE Power & Energy Magazine - November/December 2015 - 71
IEEE Power & Energy Magazine - November/December 2015 - 72
IEEE Power & Energy Magazine - November/December 2015 - 73
IEEE Power & Energy Magazine - November/December 2015 - 74
IEEE Power & Energy Magazine - November/December 2015 - 75
IEEE Power & Energy Magazine - November/December 2015 - 76
IEEE Power & Energy Magazine - November/December 2015 - 77
IEEE Power & Energy Magazine - November/December 2015 - 78
IEEE Power & Energy Magazine - November/December 2015 - 79
IEEE Power & Energy Magazine - November/December 2015 - 80
IEEE Power & Energy Magazine - November/December 2015 - 81
IEEE Power & Energy Magazine - November/December 2015 - 82
IEEE Power & Energy Magazine - November/December 2015 - 83
IEEE Power & Energy Magazine - November/December 2015 - 84
IEEE Power & Energy Magazine - November/December 2015 - 85
IEEE Power & Energy Magazine - November/December 2015 - 86
IEEE Power & Energy Magazine - November/December 2015 - 87
IEEE Power & Energy Magazine - November/December 2015 - 88
IEEE Power & Energy Magazine - November/December 2015 - 89
IEEE Power & Energy Magazine - November/December 2015 - 90
IEEE Power & Energy Magazine - November/December 2015 - 91
IEEE Power & Energy Magazine - November/December 2015 - 92
IEEE Power & Energy Magazine - November/December 2015 - 93
IEEE Power & Energy Magazine - November/December 2015 - 94
IEEE Power & Energy Magazine - November/December 2015 - 95
IEEE Power & Energy Magazine - November/December 2015 - 96
IEEE Power & Energy Magazine - November/December 2015 - 97
IEEE Power & Energy Magazine - November/December 2015 - 98
IEEE Power & Energy Magazine - November/December 2015 - 99
IEEE Power & Energy Magazine - November/December 2015 - 100
IEEE Power & Energy Magazine - November/December 2015 - 101
IEEE Power & Energy Magazine - November/December 2015 - 102
IEEE Power & Energy Magazine - November/December 2015 - 103
IEEE Power & Energy Magazine - November/December 2015 - 104
IEEE Power & Energy Magazine - November/December 2015 - 105
IEEE Power & Energy Magazine - November/December 2015 - 106
IEEE Power & Energy Magazine - November/December 2015 - 107
IEEE Power & Energy Magazine - November/December 2015 - 108
IEEE Power & Energy Magazine - November/December 2015 - 109
IEEE Power & Energy Magazine - November/December 2015 - 110
IEEE Power & Energy Magazine - November/December 2015 - 111
IEEE Power & Energy Magazine - November/December 2015 - 112
IEEE Power & Energy Magazine - November/December 2015 - Cover3
IEEE Power & Energy Magazine - November/December 2015 - Cover4
https://www.nxtbook.com/nxtbooks/ieee/powerelectronics_september2021
https://www.nxtbook.com/nxtbooks/pes/powerenergy_091021
https://www.nxtbook.com/nxtbooks/pes/powerenergy_070821
https://www.nxtbook.com/nxtbooks/pes/powerenergy_050621
https://www.nxtbook.com/nxtbooks/pes/powerenergy_030421
https://www.nxtbook.com/nxtbooks/pes/powerenergy_010221
https://www.nxtbook.com/nxtbooks/pes/powerenergy_111220
https://www.nxtbook.com/nxtbooks/pes/powerenergy_091020
https://www.nxtbook.com/nxtbooks/pes/powerenergy_070820
https://www.nxtbook.com/nxtbooks/pes/powerenergy_050620
https://www.nxtbook.com/nxtbooks/pes/powerenergy_030420
https://www.nxtbook.com/nxtbooks/pes/powerenergy_010220
https://www.nxtbook.com/nxtbooks/pes/powerenergy_111219
https://www.nxtbook.com/nxtbooks/pes/powerenergy_091019
https://www.nxtbook.com/nxtbooks/pes/powerenergy_070819
https://www.nxtbook.com/nxtbooks/pes/powerenergy_050619
https://www.nxtbook.com/nxtbooks/pes/powerenergy_030419
https://www.nxtbook.com/nxtbooks/pes/powerenergy_010219
https://www.nxtbook.com/nxtbooks/pes/powerenergy_111218
https://www.nxtbook.com/nxtbooks/pes/powerenergy_091018
https://www.nxtbook.com/nxtbooks/pes/powerenergy_070818
https://www.nxtbook.com/nxtbooks/pes/powerenergy_050618
https://www.nxtbook.com/nxtbooks/pes/powerenergy_030418
https://www.nxtbook.com/nxtbooks/pes/powerenergy_010218
https://www.nxtbook.com/nxtbooks/pes/powerenergy_111217
https://www.nxtbook.com/nxtbooks/pes/powerenergy_091017
https://www.nxtbook.com/nxtbooks/pes/powerenergy_070817
https://www.nxtbook.com/nxtbooks/pes/powerenergy_050617
https://www.nxtbook.com/nxtbooks/pes/powerenergy_030417
https://www.nxtbook.com/nxtbooks/pes/powerenergy_010217
https://www.nxtbook.com/nxtbooks/pes/powerenergy_111216
https://www.nxtbook.com/nxtbooks/pes/powerenergy_091016
https://www.nxtbook.com/nxtbooks/pes/powerenergy_070816
https://www.nxtbook.com/nxtbooks/pes/powerenergy_050616
https://www.nxtbook.com/nxtbooks/pes/powerenergy_030416
https://www.nxtbook.com/nxtbooks/pes/powerenergy_010216
https://www.nxtbook.com/nxtbooks/ieee/powerenergy_010216
https://www.nxtbook.com/nxtbooks/pes/powerenergy_111215
https://www.nxtbook.com/nxtbooks/pes/powerenergy_091015
https://www.nxtbook.com/nxtbooks/pes/powerenergy_070815
https://www.nxtbook.com/nxtbooks/pes/powerenergy_050615
https://www.nxtbook.com/nxtbooks/pes/powerenergy_030415
https://www.nxtbook.com/nxtbooks/pes/powerenergy_010215
https://www.nxtbook.com/nxtbooks/pes/powerenergy_111214
https://www.nxtbook.com/nxtbooks/pes/powerenergy_091014
https://www.nxtbook.com/nxtbooks/pes/powerenergy_070814
https://www.nxtbook.com/nxtbooks/pes/powerenergy_050614
https://www.nxtbook.com/nxtbooks/pes/powerenergy_030414
https://www.nxtbook.com/nxtbooks/pes/powerenergy_010214
https://www.nxtbookmedia.com