PowersystemoperationsandcontrolUnitsgenration.pdf

Power system operations and control power generation units

1. Electric Power Generation,
Operation, and Control
02-Characteristics of Power Generation
Units
1

2. Lecture Outline
❑ReviewofPowerSystemOperationConcepts
❑EconomicImportance
❑CharacteristicsofSteamUnits
❑VariationsinSteamUnitCharacteristics
❑Hydroelectricunitinput–outputcurve
❑EnergyStorage
2

3. Review of Power System Operation Concepts
❑Generatorsthatderivetheiroutputfromburningfuel
3

4. Review of Power System Operation Concepts
❑ConceptsMultipleGenerators
How do we allocate MW output
to the generators to minimize the
total cost of operating all generators
The Economic Dispatch Problem
4

5. Review of Power System Operation Concepts
❑ConceptsMultipleGeneratorsScheduling Generation to meet hourly load
the Unit Commitment Problem0 20 40 60 80 100 120 140160 180
1000
1200
1400
1600
1800
2000
2200
2400
2600
2800
3000 Hours
MW
Hourly load for one week
Sunday Monday Tuesday Wednesday Thursday Friday Saturday
5

6. Review of Power System Operation Concepts
❑Incorporatinggeneratorswithhydrounitsonrivernetworksandfueldeliverynetworks
Schedule hydro to
avoid overflow of
reservoirs
Schedule oil usage to not
empty storage tank until new
supplies are available
6

7. Review of Power System Operation Concepts
❑ConceptsTransmissionSystem
❖Operationsmusttaketransmissionsysteminto
account
•Alllinesandtransformerflowswithinlimit
•Allbusvoltagemagnitudeswithinlimit
•No“firstcontingency”outageswillresultinanyflow
orvoltagelimitviolations(the(N-1)rule)
•Anyviolationsmustbe“corrected”
•Economicdispatchmustaccountfortransmission
losses
7

8. Review of Power System Operation Concepts
❑ConceptsPowerSystemOperations
8

9. Review of Power System Operation Concepts
❑ConceptsControlofGeneration
9

10. Characteristics of Steam Units
❑Input–outputcharacteristicsofathermalpowergenerationunit.
❑Atypicalboiler–turbine–generatorunit
❑Grossinput--totalinput($/hrs,tons/hr(coal)Mcf/hr(gas))
❑Netoutput–Wattsavailabletotheelectricutilitysystem.
2-6%
94-98%
Rs/h or tons coal/h
Mcf gas/h
Electrical power, P
10

11. Characteristics of Steam Units
❑Inthecontrolledoperationofpowersystems,therearemanypossibleparametersof
interest.
❑Fundamentaltotheeconomicoperatingproblemisthesetofinput–outputcharacteristics
ofathermalpowergenerationunit.
❑Graphs
❖Point
❖Line-1
st
degreePolynomial
❖Curve-2
nd
degreePolynomial
11

12. Characteristics of Steam Units
❑Input-OutputCharacteristicsCurve
❖Input
•??????=btuperhourheatinputtotheunitor(MBtu/h)
•??????=fuelcosttimes??????isthe$perhour($/h)inputtotheunitforfuel
•The$/hoperatingcostrateofaunitwillincludeproportionaloperationandmaintenance
costs
❖Output
•Netelectricalpower,??????MW
The input-output curve of a steam turbine generator in idealized form
??????=�+�??????+�??????
2
12

13. Characteristics of Steam Units
❑Incrementalheatratecharacteristic
❖Incrementalheatratecharacteristicistheslope(thederivative)oftheinput–outputcharacteristic(ΔH/ΔP
orΔF/ΔP).
❖ItisconvertedtoanincrementalfuelcostcharacteristicBtu/KWh×$/Btu
❖Frequently,thischaracteristicisapproximatedbyasequenceofstraight-linesegments
??????=�+�??????+�??????
2
??????=�+�??????
�??????
�??????
=�+2�??????
�??????
�??????
=�
�
2
??????
�
2
??????
=2� �
2
??????
�
2
??????
=0
13

14. Characteristics of Steam Units
❑Theunit(net)heatratecharacteristicofasteamunit
❖ThischaracteristicisH/PversusP.
❖Itisproportionaltothereciprocaloftheusualefficiencycharacteristicdevelopedformachinery
❖Atypicalheatrateis10,500Btu/kWh
A kilowatt hour has a thermal equivalent
of approximately 3412 Btu
14

15. Characteristics of Steam Units
❑
??????=�+�??????+�??????
2
??????=�+�??????
�??????
�??????
=�+2�??????
�??????
�??????
=�
�
2
??????
�
2
??????
=2�
�
2
??????
�
2
??????
=0
15

16. Variations in Steam Unit Characteristics
❑
nonconvex
convex
16

17. Variations in Steam Unit Characteristics
❑Thecommon-headerplant
❑Toppingturbine
17

18. Variations in Steam Unit Characteristics
❑CombinedCycleUnits.
18

19. Variations in Steam Unit Characteristics
❑CogenerationPlants
❖Cogenerationplantsarelikethecommon-headersteamplants
❖Designedtoproducebothsteamandelectricity
19

20. Hydroelectric unit input–output curve
20

21. Input–output characteristics for a pumped storage hydroplant with a
fixed, net hydraulic head.
21

22. Energy Storage
22
❑Example

23. Characteristics of Steam Units
23
❑Example–
❖Plottheinput–outputcharacteristicsforeachunitexpressinginputinMbtuperhourandoutputinMW.
❖Assumethattheminimumloadingofeachunitis20MWandthatthemaximumloadingis100MW.
❖??????
1=8??????
1+0.024??????
1
2
+80
❖??????
2=6??????
2+0.04??????
2
2
+120
?????? ??????
�??????
�
20 250 256
30 342 336
40 438 424
50 540 520
60 646 624
70 758 736
80 874 856
90 994 984
100 1120 1120

24. Characteristics of Steam Units
24
❑Example -Calculate the net heat rate in Btu per kilowatt-hour, and plot against the output in megawatts
❖??????
1=8??????
1+0.024??????
1
2
+80
❖??????
2=6??????
2+0.04??????
2
2
+120
❖??????
1/??????
1=(8??????
1+0.024??????
1
2
+80)/??????
1
❖??????
2/??????
2=(6??????
2+0.04??????
2
2
+120)/??????
2
P ??????
�/??????
�??????
�/??????
�
20 12480 12800
30 11387 11200
40 10960 10600
50 10800 10400
60 10773 10400
70 10823 10514
80 10920 10700
90 11049 10933
100 11200 11200

25. Characteristics of Steam Units
25
❑Example -Assume that the cost of fuel is 1.5 $ /MBtu. Calculate the incremental production cost in $ /MWh of each
unit, and plot against output in megawatts
❖??????
1=8??????
1+0.024??????
1
2
+80
❖??????
2=6??????
2+0.04??????
2
2
+120
❖??????
1=??????
1×1.5=12??????
1+0.036??????
1
2
+120
❖??????
2=??????
2×1.5=9??????
2+0.06??????
2
2
+180
❖
????????????
1
????????????1
=12+2×0.036??????
1
❖
????????????
2
????????????
2
=9+2×0.06??????
2
P dF1/dP1dF2/dP2
20 13.44 11.40
30 14.16 12.60
40 14.88 13.80
50 15.60 15.00
60 16.32 16.20
70 17.04 17.40
80 17.76 18.60
90 18.48 19.80
100 19.20 21.00

26. Characteristics of Steam Units
26
❑Homework Assignment 01-Class attendance
❑Assume that the fuel inputs in MBtu per hour, for units 1, 2, and 3, all are on-line, are given in table.
❑Where ??????
??????is the fuel input to unit ??????in MBtu per hour (millions of Btu per hour and ??????
??????is the unit output in megawatts
❑Plot
a)the input–output characteristics for each unit expressing input in Mbtuper hour and output in megawatts.
b)Calculate the net heat rate in Btu per kilowatt-hour, andplot it against output in megawatts.
c)Calculatethe incremental production cost in $ /MWh of each unit, and plot against output in megawatts.