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2nd UCTE project
TrainingPhase 1
Item 1
Theoretical Description of
Load-Frequency Control
Oguz YILMAZ
Tubitak-UZAY
oguz.yilmaz@uzay.tubitak.gov.tr
• Load-Frequency Control
• Primary Control (Local Control)
• Secondary Control (General System
Control)
• Tertiary Control (Control of Minute Reserve
or Scheduled Reserve)
• Time Control
• Example Simulations with Dynamic ModelsFor further inquiry,
https://www.entsoe.eu/resources/publications/entso-
e/operation-handbook//
Summary
Control over the time line after a frequency deviation
5
Primary Frequency Control
Purpose
Establishment of balance between
Generation-Load
Balance can be lost in miliseconds (breaker trip/closure)
Time is required for generation level change (seconds)
Kinetic energy change of rotating masses,
=> frequency deviation
Continuous, automatic, proportional response of generating units to frequency deviation
oguz.yilmaz@uzay.tubitak.gov.tr
10
units
max.
1) 7 units
1) 7 units
1) 50 units
2a) 7=>9 units (unexpected
increase in flow )
2b1) 50=>49 change in
level
2b2) 7=>9 increase in flow
2c) =>49.8 @ the new
balance
50
49
Safety
valve
Primary Frequency Control-Analogy
oguz.yilmaz@uzay.tubitak.gov.tr
Generation=Load
Generation < Load
Generation=Load
Reestablishment of the
balance between
generation&load, and a
new steady state value
for the frequency.
8
Example Simulations
Scenario 1Combined Cycle=0.97; Hydro=0.90, CoalFired=1;
Secondary Control inactive.
@ T=10.sec extra step load of 2%.
Tsim=250 sec
Scenario 2Combined Cycle=0.92; Hydro=0.90, CoalFired=0.98;
Secondary Control inactive.
@ T=10.sec Extra step load of 2%.
Tsim=250 sec
oguz.yilmaz@uzay.tubitak.gov.tr
9
Secondary Frequency Control
Purpose
Eliminate frequency deviation
Maintain the interchange flows at the scheduled values
System-wide, central control over a group of generating units
AGC (Automatic Generation Control)
oguz.yilmaz@uzay.tubitak.gov.tr
Ideal secondary control
after a loss of generation
11
Secondary Frequency Control
Definitions
Control Area
Eg. Turkey or Bulgaria ...
Area Control Error
ACE = Actual instantaneous net interchange– scheduled net interchange – Calculated* primary control contribution
Kri => K-factor (MW/Hz) defined for the specified control area
AGC Secondary Control Parameters
+ Export
- Import
ß => P, 1/Tr =I
PI Control !!!
oguz.yilmaz@uzay.tubitak.gov.tr
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Secondary Frequency Control
Control Reserve
oguz.yilmaz@uzay.tubitak.gov.tr
13
Simulation Examples
Scenario 3Combined Cycle=0.92; Hydro=0.90, CoalFired=0.98;
Sekondary Control active. (only hydro)
@ T=10.sec extra step load of %2.
@ T=250.sec extra step load of %1
Tsim=600 sec
Scenario 4Combined Cycle=0.92; Hydro=0.90, CoalFired=0.98;
Sekondary Control active. (hydro+combined cycle)
@ T=10.sec extra step load of %2.
@ T=250.sec extra step load of %1
Tsim=600 sec
oguz.yilmaz@uzay.tubitak.gov.tr
14
Tertiary Frequency Control
Purpose
Provision of reserve continuity for Secondary Control (scheduled activation)
For large incidents, provision of secondary
reserve (direct activation) (minute-reserve)
Distribution of Control Reserve among generating units or committed units, depending on ECONOMY and SAFETY
oguz.yilmaz@uzay.tubitak.gov.tr
15
Tertiary Control
22/09/0916
Geneation-Load Unbalance
and Control over the Time axis
17
Example Simulations
Scenario 5Combined Cycle=0.92; Hydro=0.90, CoalFired=0.98;
Secondary Control active. (hydro + combined cycle)
@ T=10.sec extra step load of %2.
@ T=250.sec extra step load of %1
@T=700.sec Tertiary Reserve 1 is being activated
Tsim=1200 sec
Scenario 6Combined Cycle=0.92; Hydro=0.90, CoalFired=0.98;
Secondary Control active. (hydro + combined cycle)
@ T=10.sec extra step load of %2.
@ T=250.sec extra step load of %1
@T=700.sec Tertiary Reserve 1 is being activated (0.45 pu)
@T=1200. sec Tertiary Reserve 2 is being activated (0.45 pu)
Tsim=2000 secoguz.yilmaz@uzay.tubitak.gov.tr
22/09/0918
Time Control
Purpose
When fgerçek not controlled with quality and integral error increases,
fset set different than 50 Hz to minimize integral error.
oguz.yilmaz@uzay.tubitak.gov.tr
19
Example Simulations
Scenario 7Between T=2000. sec and T=2400. sec, time control
fset=50.05
Tsim=2500 sec.
oguz.yilmaz@uzay.tubitak.gov.tr
20
Emergency Control
Purpose
In case generation-load unbalance can not be maintained with 3-stage control, reestablisment of balance with unpreferred methods
Under frequency load-shedding
Instantaneous Demand Control (new approach)
Generation Tripping
Configuration change at plant load control systems (deactivation of load controllers, limiters)
oguz.yilmaz@uzay.tubitak.gov.tr
21
Simulation Examples
Scenario 8Combined Cycle=0.92; Hydro=0.90, CoalFired=0.98;
Secondary Control active. (hydro + combined cycle)
@ T=10.sec extra step load of %2.
@ T=250.sec extra step load of %1
@T=700.sec Tertiary Reserve 1 is being activated (0.45 pu)
@T=1200. sec Tertiary Reserve 2 is being activated (0.45 pu)
Time control between T=2000. sec and T=2400. sec
@T=2700.sec extra load of %10 begins to activate.
Tsim=3500 sec.
oguz.yilmaz@uzay.tubitak.gov.tr
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