1

State Estimation for

Advanced Distribution Automation

Mesut Baran Department of Electrical and Computer Engineering

North Carolina State University

baran@ncsu.edu

SE Problem:

Given a set of measurements z, estimate x

State Estimation: Main Tool for

System Monitoring and Control

X = [Vi/qi ]

Vi/qi

for radial feeders x > load SE -> Load Monitoring

Basic Requirements: -Need accurate system model -Need redundant measurements

Very Limited Measurements

SE Challenges for DS Application

(Po Qo) ,

sub SCADA

feeder

SCADA

I k Pc, V

AMI

- Load Data requires full scale AMI

(Vo)

Accurate System Model

• accurate system data

- Lines, DT

• Need monitoring

- Switches

- Volt/Var devices

- DG and Storage

SE Challenges for DS Application

AC

Charging

Station

AC

S

CB

R

VR

Fixed (D/S)

Compensator

Switched Cap bank

AMI

Normally Open Tie

Normally Open Tie Switch

CB

DG

Single Phase Sectionalizer

Three Phase Fuse

Three Phase Recloser

DG

Residential load

with PV panel

Three Phase Lateral

Single Phase Lateral

CES

Distribution Substation Bus

Distribution Transformer

(DT)

EV

5

DSE: State of the Art

Load Data: Historical Data

• Customer Billing --> class, kWh

• Load Surveys --> Load Curves

• Model: Feeder topology is updated manually

• Limited Real Time Data:

Use Load Data as pseudo-measurements

• SE methods: - Power Flow

- WLSE nodal, WLSE branch current

- Others

DSE enables on-line monitoring of

DSE for System Monitoring & Control

• Load & Voltage profiles system loading control actions

- Volt/Var Control - Conservation Voltage Reduction

Feeder restoration

• Feeder Topology

switch operation

Cap bank

FLISR

Goal: Conservation Voltage Reduction

SE performance: estimate Vs with accuracy of +/- 2V

0.0028 . .V p u

1

2 3 5 6 7 8 12 14 15 16

18

19

22

24

25 2629

27

2832 33

30

31

23

4 9 10 11 13 17 20

21

Vm18

34

M1 Cm14

Meter (power)

Meter (current)

Meter (voltage)

Cm22

BCSE Application

Estimate Voltages with 120 +/- 2 V accuracy