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MVAR control, integration of
wind generation to grid,
plausible solutions for supporting
quality power and reliable grid in
free markets
Diran Obadina
Principal, Systems Development
ERCOT
July 29, 2015
Paper Number 15PESGM2585
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Current Records – July 15, 2015
Peak Demand Record: 68,305 megawatts (MW)
 68,305 MW, August 3, 2011
Weekend Record
 65,159 MW, Sunday, August 28, 2011
Winter Peak Record: 57,265 MW
 57,265 MW, February 10, 2011
June 2015 Demand
- 61,732 MW, June 10
June 2014 Demand
- 59,786 MW, June 30
Wind Generation Records (instantaneous)

•
11,154 MW, February 19, 2015, 10:52 p.m.
- Non-Coastal Wind Output = 9,872 MW
- Coastal Wind Output = 1,282 MW
- Supplying 34.2% of the load
- Active Wind Capacity = 13,370 MW
40.58% Wind Penetration, March 29, 2015, 2:12 a.m.
- Total Wind Output = 10,308 MW
- Total Load = 25,400 MW
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Wind Generation – June 30, 2015
25,000 MW
ERCOT Wind Installations by Year (as of end of June 2015)
Cumulative MW Installed
IA Signed-Financial Security Posted
23,407
22,607
IA Signed-No Financial Security
3,590
4,390
20,000 MW
16,365
5,593
15,000 MW
5,593
2,941
12,470
11,065
10,407
10,000 MW
9,400
9,604
8,916
8,005
13,424
13,424
13,424
2015
2016
2017
12,470
4,785
5,000 MW
8,916
9,400
9,604
2010
2011
10,407
11,065
8,005
2,875
4,785
1,854
977
1,173
1,385
816
116
816
977
1,173
1,385
2000
2001
2002
2003
2004
0,000 MW
2,875
1,854
2005
2006
2007
2008
2009
2012
2013
2014
The data presented here is based upon the latest registration data provided to ERCOT by the resource owners and can change wi thout notice. Any capacity changes will be reflected in current and subsequent years' totals.
Scheduling delays will also be reflected in the planned projects as that information is received. This chart reflects planned units in the calendar year of submission rather than installations by peak of year shown.
Financial security posted for funding interconnection facilities does not include CREZ security deposits, which are refunded to the Interconnecting Entity when an IA is signed.
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Cumulative Installed and Planned Solar Capacity
Megawatts
12,000
10,346
10,000
7,756
8,000
6,000
10,153
4,000
7,563
Cumulative MW Under Study
Cumulative MW Installed
15
42
82
121
191
2010
2011
2012
2013
2014
288
193
2015
95
2,000
193
193
2016
2017
0
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COMPETITIVE RENEWABLE ENERGY ZONES
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Challenges of Voltage control
• Large wind power farms with little or no local loads
served and/or large synchronous machines in the
zone affecting system stability
• Long, highly compensated 345KV transmission lines
to load centers in the north and east;
– Critical voltage at voltage collapse point is relatively high which
could put the system at risk even when the voltages are within
normal ranges
• Multiple wind resource and transmission owners
– Consideration of fairness in a competitive environment.
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Wind Power vs 345 KV Voltage
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Proposed Framework
Load
Forecast
Wind
Forecast
Current
Operating
Plan
Contingency
List
Reactive Resource
Scheduling
Outage
Schedules
Transmission Operators
SCADA
EMS
Real time
Reactive
Dispatch
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Reactive Resource Scheduler
• Schedules switchable reactive devices over multiple hours
into the future
• Objective is to minimize number of switching needed over
the scheduling horizon in order to maintain voltage
• Maintain adequate reactive reserve in defined reactive areas
• Executes in the day-ahead following RUC and then hourly to
refine the day-ahead schedules
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Forecasted Load -Curve
Scheduling Horizon; Scheduling Interval; Load Curve
…
…
Scheduling horizon (T)
time
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Reactive Resource Scheduling Objective
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Reactive Resource Scheduling
•
•
•
•
Scheduling Horizon: 12-24 hours
Scheduling Interval: 30-60 mins
Works with the RT Reactive Dispatch
Maintains adequate reserve with the voltage
control area
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Reactive Resource Scheduler - Controls
•
•
•
•
•
Shunt Capacitors
Shunt reactors
Line switching
Unit commitment
Invokes Reactive Dispatch
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Real Time Reactive Dispatch
• Executes in the Real Time Sequence
• Objective – Manage the voltage across the
ERCOT grid
–
–
–
–
Secure base case voltage ranges throughout system
Maintain post contingency voltages
Restore post-event secure voltage profile
Minimum shift/minimum number of controls objective
function
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Real Time Reactive Dispatch - Controls
•
•
•
•
Generator AVR Target Voltage
Synchronous Condenser AVR Target Voltage
SVC Target Voltage
On-line Transformer Taps
– Tap position
– Target voltage
• Invokes the Reactive Resource Scheduling
(RRS) in case of infeasibility
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Thank You!