Oncor Electric Delivery

Study on Residential Electric Vehicle Charging

SWEDE Conference 2012Ron Shipman

2Oncor Electric Delivery

Introduction

•Impact of EV chargers on our system?

•Problems?

•Severity?

•Required Actions?

3Oncor Electric Delivery

Selection of Study Sites

Voltage (kV)

Peak Season

Area Year Built

Construction Characteristics

12.5 Summer Fort Worth 1965 Overhead (OH) w/ secondary

13.2 Summer Dallas 1965 OH parallel transformers w/ secondary

12.5 Summer Fort Worth 1976 Underground (UG) w/o secondary

12.5 Winter Plano 1979 UG w/ secondary (no flicker consideration)

24.9 Summer Round Rock 2006 UG w/ secondary

4Oncor Electric Delivery

Study Parameters

•Modeled Distribution System

•Coincident Peak AMS Data

•Simulated Chargers

Level 2 Charging

Penetration Levels

Multiple Scenarios

5Oncor Electric Delivery

CYME Subdivision Modeling

C

C

C

C

C

CC

C C

C

C

C

C

C

CC

C

CC

C

CC

C

C

C

C

C

C

C

B B

C

C

C

C

C

C

A

A

AA

Overview Map

6Oncor Electric Delivery

CYME Subdivision Modeling (cont’d)

•Maximum local transformer impedance

•Minimum service size

•Modeled Triplex

7Oncor Electric Delivery

AMS Generated 24-Hour Load Profile

Average Load Data

0

1

2

3

4

5

6

0:15

1:15

2:15

3:15

4:15

5:15

6:15

7:15

8:15

9:15

10:1

511

:1512

:1513

:1514

:1515

:1516

:1517

:1518

:1519

:1520

:1521

:1522

:1523

:15

Time of Day

Div

ersi

fied

Lo

ad [

kW]

Average Load

Average Load (Averaged)

SCADA Load per Cust.

8Oncor Electric Delivery

Results

•Fuse Loading

•Primary Cable Loading

•Transformer Loading

•Secondary Cable Loading

•Service Cable Loading

•Voltage Drop

•Localized Issues

9Oncor Electric Delivery

Locations EV and EVGO Requested

•2011 – 157 Locations

•2012 - 25 Locations to Date

•Addressed (2) Transformers

•Addressed (1) Secondary Cable

•Installed 19 EVGO Locations

10Oncor Electric Delivery

Questions?