Upload
ashwin-gopinath
View
225
Download
0
Embed Size (px)
Citation preview
8/6/2019 ATPS - State Estimation S8
1/21
State EstimationState Estimation
Remote Terminal Unit (Remote Terminal Unit (RTURTU) installed at a substation) installed at a substation door opendoor open
8/6/2019 ATPS - State Estimation S8
2/21
Plays very important role inPlays very important role in MonitoringMonitoring ofPSofPS
ControlControl ofPSofPS
Security controlSecurity control
Economic DispatchEconomic Dispatch
AimAim ObtainObtain bestbest system state variablessystem state variables to fit ato fit a
scatter of datascatter of data
Scatter of data due toScatter of data due to Imperfect measurementsImperfect measurements Variations in transmission line linear modelsVariations in transmission line linear models
Line charging etcLine charging etc
8/6/2019 ATPS - State Estimation S8
3/21
Imperfect measurements are due toImperfect measurements are due to Signal noiseSignal noise
Metering accuracyMetering accuracy AA\\ D conversionD conversion
NoisyNoisy datadata areare bestbest modeledmodeled asas randomrandom
variablesvariables
HenceHence estimatingestimating statestate variablesvariables isis basedbased ononstatisticalstatistical criterioncriterion
InIn PS,PS, statestate variablesvariables areare voltagevoltage magnitudesmagnitudes && phasephase anglesangles atat systemsystem
nodesnodes
8/6/2019 ATPS - State Estimation S8
4/21
HistoryHistory
MajorMajor developmentsdevelopments takentaken placeplace inin aerospaceaerospace
fieldfield inin 2020thth centurycentury
ProblemProblem:: LocationLocation ofof aerospaceaerospace vehiclevehicle(missile,(missile, airplane,airplane, spacespace vehicle)vehicle)
:: EstimationEstimation of itsof its trajectorytrajectory
(Given redundant & imperfect measurements of(Given redundant & imperfect measurements of
position & velocity)position & velocity)
8/6/2019 ATPS - State Estimation S8
5/21
Definition of State EstimationDefinition of State Estimation
IsIs thethe processprocess ofof assigningassigning aa
valuevalue toto anan unknownunknown systemsystem statestate
variablevariable basedbased onon measurementsmeasurements fromfrom
thatthat systemsystem accordingaccording toto somesome
(statistical)(statistical) criteriacriteria
8/6/2019 ATPS - State Estimation S8
6/21
State EstimatorsState Estimators
TheyThey areare thethe methodsmethods \\ algorithmsalgorithms,,
developeddeveloped usingusing measurementsmeasurements fromfrom
networknetwork toto calculatecalculate statestate ofof networknetwork
PurposePurpose::
DetectDetect badbad // incorrectincorrect datadata DetectDetect changeschanges inin networknetwork configurationconfiguration
ReplaceReplace faultyfaulty // missingmissing datadata
8/6/2019 ATPS - State Estimation S8
7/21
Data collection from PSData collection from PS
8/6/2019 ATPS - State Estimation S8
8/21
?PS State Estimation?PS State Estimation
Problems in monitoring transmission systemProblems in monitoring transmission system
Nature of measurement transducersNature of measurement transducers
Communication problemsCommunication problems in transmitting valuesin transmitting values
back to operations control centreback to operations control centre
Transducers are subject toTransducers are subject to errorserrors
Telemetry equipments experience comm. channelTelemetry equipments experience comm. channel
outout no informationno information of some part of systemof some part of system
These are the reasons for developing PS SEThese are the reasons for developing PS SE
8/6/2019 ATPS - State Estimation S8
9/21
Principles of State EstimationPrinciples of State Estimation
ConsiderConsider aa DCDC loadload flowflow exampleexample ofof 33--busbus
systemsystem
OnlyOnly informationinformation providedprovided isis byby threethree MWMW
powerpower flowflow metersmeters asas shownshown inin figfig.. meter meter
placementplacement
OnlyOnly TwoTwo ofof thethe metersmeters areare requiredrequired toto
calculatecalculate busbus phasephase angles,angles, loadload &&
generationgeneration valuesvalues fullyfully
8/6/2019 ATPS - State Estimation S8
10/21
33 -- bus systembus system
8/6/2019 ATPS - State Estimation S8
11/21
Meter placementMeter placement
8/6/2019 ATPS - State Estimation S8
12/21
Case 1Case 1
SupposeSuppose metersmeters MM1313 && MM3232 areare usedused
SupposeSuppose MM1313 && MM3232 givegive usus perfectperfect readingsreadings ofof
flowsflows onon theirtheir respectiverespective transmissiontransmission lineslines
MM1313 = 5 MW = 0.05 pu= 5 MW = 0.05 pu
MM3232 = 40 MW = 0.40 pu= 40 MW = 0.40 pu
FlowsFlows onon lineslines 11--33 && 33--22 cancan bebe setset toto metermeter readingsreadings
8/6/2019 ATPS - State Estimation S8
13/21
puMxf 05.0)(
11331
1313 !!! UU
puMx
f 40.0)(1
322332
32 !!! UU
We knowWe know 33 = 0, s= 0, solve the above equationsolve the above equations
rad02.01 !U rad10.02 !U&&
8/6/2019 ATPS - State Estimation S8
14/21
Case 2Case 2
All three meter readings have slight errorsAll three meter readings have slight errors
Suppose readings obtained areSuppose readings obtained are
Suppose meters MSuppose meters M1313 & M& M3232 are used as beforeare used as before
puW 62.06212 !!
puMWM 06.0613 !!
puW 37.03732 !!
8/6/2019 ATPS - State Estimation S8
15/21
Calculate phase anglesCalculate phase angles
This results in system flows as shown in fig.This results in system flows as shown in fig.
Flow on line 1Flow on line 1--2 does not match2 does not match
rad0925.02 !U
rad03 !U
rad024.01 !U
8/6/2019 ATPS - State Estimation S8
16/21
Flows resulting from use of meters MFlows resulting from use of meters M1313 & M& M3232
8/6/2019 ATPS - State Estimation S8
17/21
Case 3Case 3
Suppose meters MSuppose meters M1212 & M& M3232 are usedare used
Calculate phase angles & line flowsCalculate phase angles & line flows
This results in system flows as shown in fig.This results in system flows as shown in fig.
Flow on line 1Flow on line 1--3 does not match3 does not match
8/6/2019 ATPS - State Estimation S8
18/21
Flows resulting from use of meters MFlows resulting from use of meters M1212 & M& M3232
8/6/2019 ATPS - State Estimation S8
19/21
ConclusionConclusion
AA procedureprocedure isis neededneeded thatthat usesuses
informationinformation availableavailable fromfrom allall metersmeters toto
produceproduce thethe bestbest estimateestimate ofof actualactualangles,angles, lineline flows,flows, busbus loadload && generationsgenerations
8/6/2019 ATPS - State Estimation S8
20/21
ReferenceReference
AllenAllen JJ..WoodWood andand BruceBruce FF..Woolenberg,Woolenberg,
PowerPower generation,generation, operationoperation andand
control,control, JohnJohn WileyWiley && sonssons IncInc..
GeorgeGeorge LL Kusic,Kusic, ComputerComputer--AidedAided
Power
Power SystemsSystems Analysis,Analysis,
Prentice
Prentice--HallHallofof India,India, PvtPvt.. LtdLtd..
8/6/2019 ATPS - State Estimation S8
21/21
RTURTU
Provides interface for measurements ofProvides interface for measurements of
voltage, current , power flow, status .. tovoltage, current , power flow, status .. to
be transferred to the central computer viabe transferred to the central computer viatelemetrytelemetry
Also implements commands from the centralAlso implements commands from the centralcomputer to equipmentcomputer to equipment
backback