PSERC ProjectPSERC Project

Power System State Estimation and Optimal Measurement Placement for Distr

ibuted Multi-Utility Operation

A. Abur and G.M. Huang (PIs) J. Lei and B. Xu (Students)

Texas A&M University

OutlineOutline

Objectives Technical Approach Implementation Results Conclusions

ObjectivesObjectives

Optimal Meter Placement FACTS Device Monitoring Distributed State Estimation

Technical ApproachTechnical Approach Three step meter placement

– Choice of the minimum set– Choice of candidates– Optimal selection from candidates

FACTS device monitoring– Modeling with constraints– Incorporation into SE

Meter Placement ProblemMeter Placement Problem Choice of Essential Measurements Set.

– If the system is observable: Factorize H matrix– Else: Run LAV estimator

Candidate Identification– Form Contingency–Measurement incidence matrix

Optimal Candidate selection– Use of integer programming

ContingenciesContingencies

Types of Contingencies: Line Outage Measurement Loss Bus Split

Robustness Options: Against user defined contingency list Bad data Detectability All single line outages

Graphic User InterfaceGraphic User Interface

Add injections at bus 3 and 4

FACTS Device MonitoringFACTS Device Monitoring

UPFC Modeling: Two V-source model Four parameters Constraints

Integration into the SE: Use Hachtel’s formulation Inequality and equality constraints

Model of UPFC Physical Model of UPFC

Model of UPFC Steady State Model of UPFC

The constraint PB + PE = 0 implies that no real-power is exchanged between the UPFC and the system.

BBV

BZ

BZ

BI

BI

EEV 0 EB PP

EI

BI EZ

k m

kmkm jQP

kmkm jQP mkmk jQP

MeasurementsReal and reactive power through k-m

BkB

BkEk

E

Ekkm

B

mkkm X

VV

X

VV

X

VVP ,, sinsinsin ( 1 )

BkB

BkEk

E

Ekkm

B

mkk

EB

EEkm X

VV

X

VV

X

VVV

XX

XXQ ,,

2coscoscos

( 2 )

BmB

Bmmk

B

mkmk X

VV

X

VVP ,sinsin ( 3 )

BmB

Bmmk

B

mk

B

mmk X

VV

X

VV

X

VQ ,

2

coscos ( 4 )

ConstraintsEquality and inequality constraints of UPFC

• VB, θB, VB and θB are the control parameters of UPFC

Real Power Constraints: 0 BE PP (5)

Shunt Power Constraints: max,22

EEE TQP (6)

Series Power Constraints: max,22

BBB TQP (7)

Shunt Voltage Constraints: max,BB VV (8)

Series Voltage Constraints: max,EE VV (9)

Hachtel’s Method

0

0)(

0)(

0)(.2

1min 1

s

xhzr

xc

sxfts

rRrT

Hachtel’s Method KKT first order optimality conditions :

0

)(

)(

)(

0

00

000

00

k

k

k

TTT

xhz

xg

xf

xHGF

HR

G

FD

Example

From (bus) To (bus) XB XE VB,max VE,max SB,max SE,max

6 12 0.7 0.7 1.0 1.0 1.0 1.0

Parameters of the installed UPFC device

FACTS device (UPFC) is installed on line 6-12, near bus 6

Estimation ResultsFunction of the program as an estimat

or

Function of the program as a power flow controller

• Note that PB + PE = 0 and VB < 1.0, VE < 1.0, SB < 1.0, SE < 1.0, which correctly satisfy all the constraints.

Voltages and powers of UPFC

Set power flow in line 6-12 to be 0.1 + j0.1

Voltages and powers of UPFC

VB θB PB SB VE θE PE SE

0.1099 60.07 0.0014 0.0128 1.0679 -14.31 -0.0014 0.0035

VB θB PB SB VE θE PE SE

0.1236 9.0530 0.0056 0.0159 1.0000 -14.6037 -0.0056 0.0691

Conclusions

Optimal meter placement accounting for contingencies and loss of measurements

State estimation of systems with FACTS devices and their parameters

Setting of parameters of FACTS devices for desired power flows