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A Knowledge-Based Systemfor Supervision and Controlof Regional Voltage Profileand Security
Alessandro B. Marques Glauco N. Taranto Djalma M. Falcão Petrobras Federal University of Rio de Janeiro Formely with FURNAS COPPE Brazil Brazil
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Previous Reports
TF 38.02.23 Report DraftPorto PowerTech, 2001
A.B. Marques, G.N. Taranto, and D. M. Falcão, “A SupervisoryKnowledge-Based System For Monitoring and Control ofRegional Voltage Profile.”
IEEE Transactions on Power SystemsA.B. Marques, G.N. Taranto, and D. M. Falcão, “A Knowledge-Based System for Supervision and Control of Regional VoltageProfile and Security.” (Submitted)
TF 38.02.20 Final Report (2nd Draft)
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Cooperative Work
Federal University of Rio de Janeiro – COPPECEPELONS: The Brazilian ISOObjectives:
Analyze coordinated voltage schemes for possibleimplementation in the Brazilian SystemSurvey implementation issues and difficulties
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Motivation
Characteristics of the Q-V InteractionHighly non-linearDiscrete elements
Customized Control SchemeRadial/meshed networksShort/long linesAvailability of reactive support in the area
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Knowledge Based Systems
Most KBS uses production rules like If <condition>, Then <action or conclusion>
Uncertainty may exists in the rulesLinguistic Uncertainty (low, high, normal, etc.)Evidential Uncertainty (relationship is not certain)
Linguistic uncertainty may be efficiently dealt withby Fuzzy Logic (Linguistic Variables)Example:
1.0Very-HighHighNormalVery-Low Low
Voltage (pu)
µ (V )
0
0.85 0.90 0.95 1.00 1.05 1.10 1.15
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Fuzzy Inference System (FIS)
RULES
Inference Engine
Fuzzification Defuzzification
x
Crisp
Output
y = f(x)
Fuzzy
Input
Fuzzy
Output
Crisp
Input
If x is A, Then y is BAntecedent Consequent
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The Rio Area
Control Variables
Regulated Variables
Energy importing area with apeak load of 6,000 MWEquivalent of the BrazilianSouth/Southeastern subsystem730 buses, 1146 branches and104 generatorsLong transmission corridors(750 Km)Relatively weak reactive supportTransmission: FurnasDistribution: Light, Cerj, Escelsa
SC
Valadares
Mascarenhas
Vitória
Campos
Adrianópolis
500 345 kV
Marimbondo V. Grande
L.C.Barreto
Furnas
Aparecida
N. Peçanha
Santa CruzRIO AREA
Jacarepaguá
Grajaú
V. Redonda
Funil
Angra
C. Paulista
Itutinga
Tijuco Preto
CampinasPoços deCaldas
Araraquara
138 kV
138 kV
230 kV
230 kV
345 kV
500 kV
138 kV
F1
F2
F3
F4
138 kV
500 kV
345 kV500 kV
345 kV Corridor500 kV Corridor
about750 km (470 miles)
to Itaipu
to Jaguara
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FIS-Power System Integration
POWER
SYSTEM
FISMarimbondo (kV)
Furnas (kV)
S. Cruz (kV)
Angra (kV)
Adriano (kV)
Jacare (kV)
Grajau (Mvar)
Cap./Rea. Switching
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Linguistic Variable
Jacarepagua_138kV_Voltage
kV
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Control Scheme Overview
Hierarchical Structure
Task Oriented ControlContinuous FIS: high-side voltage set-pointsDiscrete FIS:capacitor/reactor switchingDefensive Layer: checkon voltage limits in thetransmission corridors
Set Point ControlAVRsJVCs
ContinuousFIS
DiscreteFIS
PowerSystem
JVC/AVR
DefensiveLayer
SCADA dedicated channels
High Level(task-oriented control)
Low Level(set-point control)
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Control Objectives
Minimize the number of capacitor/reactor bankswitching operationsMaximize (minimize) the generation of reactivepower from the line charging of the network inheavy (light) load conditionsHold the voltage at regulated buses smoothmost of the time, avoiding excessive spikescaused by the switching of discrete devices
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Control Objectives (cont.)
Voltage Profile Control “Keep the voltage at Jacarepagua and
Adrianopolis around the desired valuesestablished by the electric utilities of theRio Area”
Security “Keep the Grajau SC reactive power output
between zero and –100 Mvar”
3
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Continuous FIS (CFIS)
Two FIS used for differentload conditionsQualitatively both FIS usethe same rulesDifferent voltage set-pointvalues for some bussesCan be made different, ifnecessaryDecision to choose each FISis based on system demand,time of day, etc.
Heavy / MedianLoadFIS
Light / MinimumLoadFIS
SCADA
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CFIS Rules
UpDownDown
UpRE
S.Cru
SUUpUpLILowNTL5SDREREIndHighOK4RESDRELCHighOK3UpUpUpCapLowLow2REREREOKOKOK1
AngrFurnMariGrajaJacarAdriaRule
OUTPUTSINPUTS
LI – Low Inductive
RE – Remain
SU – Small-Up
SD – Small-Down
NTL – Not too Low
Cap – Capacitive
LC – Low Capacitive
Ind – Inductive
Contain 29 rules based on experience and off-linestudies. Examples:
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Control Surface
Typical nonlinear characteristic of the rules
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Discrete FIS (DFIS)
First Layer: receives informationfrom the defensive layer and outputsvague information for the amount ofreactive power to be switched on/off(few, much, too much, etc).
Second Layer: decides which shuntbank should be switched on/off ineach substation.
Third Layer: deliberates the onlyone device, among the outputs of thesecond layer that should be switchedon/off.
DeliberativeLayer
Substation#1
Substation#n
Substation#1
Substation#n
1st layer
2nd layer
3rd layer
SCADA
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DFIS RulesThe DFIS rules are specific for each layer andsubstationExample for the first layer (Jacarepagua substation)
If <Voltage is low and Adrianopolis_voltage is not too low and Grajau_output is low capacitive>, Then <switch on large amount of shunt capacitors>
Example for the second layer (Jacarepagua substation)
If <Switching on is large amount of shunt capacitors and Number of reactors switched on is zero>, Then <switch on large capacitor>
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Simulation Setup
Santa Cruz power stationnot includedLoad variation and circuitoutageAvailable switchingelementsSimulations step 5 sFIS action at every 40 s
0 2000 4000 6000 s
Trip of one 500 kV circuitAngra-Adrianopolis (300s)
Area Load (MW)
6000
3000
Banks Available In operationCapacitors inJacarepagua
2 (100 Mvar) 1
Reactors inJacarepagua
3 (30 Mvar) 0
Capacitors inAdrianopolis
3 smalls (10 Mvar)2 medians (40 Mvar)2 larges (160 Mvar)
320
Reactors inAdrianopolis
2 smalls (50 Mvar)1 large (150 Mvar)
00
4
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Simulation Tool
Fast Simulation Program (FastSim++) developed atCOPPE/Federal University of Rio de Janeiro, Brazil
Representation only of the mid and long term dynamics, like:
LTC actuation;
SVC;Demand curve
FISAdriano (kV)
Jacare (kV)
Grajau (Mvar)
Marimbondo (kV)
Furnas (kV)
S. Cruz (kV)
Angra (kV)
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Simulation Results
Event Time(sec)
Switching Event
Time(sec)
Switching
1 40 Capacitor bank atJacarepagua switched on
10 1800 Small reactor bank atAdrianopolis switched on
2 720 Small capacitor bank atAdrianopolis switched off
11 3960 Small reactor bank atAdrianopolis switched off
3 800 Small capacitor bank atAdrianopolis switched off
12 4080 Small reactor bank atAdrianopolis switched off
4 840 Small capacitor bank atAdrianopolis switched off
13 4240 Small capacitor bank atAdrianopolis switched on
5 920 Median capacitor bank atAdrianopolis switched off
14 4320 Small capacitor bank atAdrianopolis switched on
6 1080 Capacitor bank atJacarepagua switched off
15 4400 Small capacitor bank atAdrianopolis switched on
7 1280 Capacitor bank atJacarepagua switched off
16 4440 Median capacitor bank atAdrianopolis switched on
8 1440 Median capacitor bank atAdrianopolis switched off
17 4480 Capacitor bank atJacarepagua switched on
9 1640 Small reactor bank atAdrianopolis switched on
18 4640 Median capacitor bank atAdrianopolis switched on
Discrete elements switching sequence
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Marimbondo 500 kV Voltage
Initially voltage aboveupper limitLow voltage at loadbussesAntagonistic situationDefensive layer triggersDFIS that switchescapacitor banks onAt 700 sec, terminalvoltage reaches lowerlimit (not shown).DFIS orders capacitorbank switching off
0 500 1000 1500 2000 2500 3000 3500 4000 4500 5000490
500
510
520
530
540
550
560
570
580Marimbondo 500 kV
Time(sec)
Vol
tage
(kV
)
Upper Limit
Lower Limit
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Angra 500 kV Voltage
Similar behavior toMarimbondoAt 1800 sec,underexcitation limiter isreached (not shown)
0 500 1000 1500 2000 2500 3000 3500 4000 4500 5000490
500
510
520
530
540
550
560
570
580Angra 500 kV
Time(sec)
Vol
tage
(kV
)
Upper Limit
Lower Limit
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Jacarepagua 138 kV Voltage
Initial low voltageArrows represent time ofshunt bank switchingsAt 40 sec, 100 Mvarcapacitor bank switcheson
0 500 1000 1500 2000 2500 3000 3500 4000 4500 5000120
125
130
135
140
145
150Jacarepaguá 138 kV
Time(sec)
Vol
tage
(kV
)
Upper Limit
Lower Limit
jp-c-on
ad-mc-off
jp-c-off
ad-sr-off jp-c-on
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Adrianopolis 138 kV VoltageInitial low voltageDesired voltage range inheavy conditions:between 143 and 145 kVSimilar behavior toJacarepaguaWorth mentioning:smoothness between3000 and 4000 sec whenload ramp is positivePriority given tocontinuous controlsAt 4000 sec, Marimbondoreaches upper limit
0 500 1000 1500 2000 2500 3000 3500 4000 4500 5000120
125
130
135
140
145
150Adrianópolis 138 kV
Time(sec)
Vol
tage
(kV
)
Upper Limit
Lower Limit
jp-c-on jp-c-off
ad-mc-off
5
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Grajau SC Reactive Power
Output most of the timeremains within desirablerange [ -100 ; 0 Mvar]Fast response at 300 secwhen a 500 kV circuittrips out.
0 500 1000 1500 2000 2500 3000 3500 4000 4500 5000-400
-300
-200
-100
0
100
200
300
400
500Grajaú SC Mvar
Time(sec)
Rea
ctiv
e P
ower
Upper Limit
Lower Limit
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Final Remarks
Encouraging results in the experimentconducted with a model of the Rio AreaCan be used as a decision support tool tohelp operators or as an automatic controltoolFuture work: tests with present systemconfiguration