Conservation Voltage Reduction (CVR)

Phillip Anderson P.E.

Engineering Project Leader

Research, Development & Deployment

Presentation Outline

• Background Information on CVR

– CVR Definition

– Voltage Control Theory

– CVR Theory

– Northwest Energy Efficiency Alliance Distribution Efficiency Initiative (DEI) Pilot Study

• Idaho Power CVR Implementation to Date

What is Conservation Voltage Reduction?

By reducing distribution feeder service voltage, Conservation Voltage Reduction (CVR) promises to reduce energy consumption.

What is Service Voltage?

• Voltage at point of delivery (at the meter)

• National Service Voltage Standard (ANSI C84.1) – “Range A” or Normal Conditions: 114 V-126 V

– Allows ± 5% service voltage bandwidth

• All electric devices operate properly

126 Volts

120 Volts

114 Volts

+5%

0%

-5%

National Standard

Typical Urban Feeder

• Typical Urban “Feeder” operates in upper half (120-126 V)

Typical Urban Feeder Voltage Profile

114

116

118

120

122

124

126

0 0.5 1 1.5 2 2.5 3 3.5 4

Serv

ice

Vo

lts

Miles from Substation

Typical Service Voltage

Pre CVR

124 Volts at Substation

120 Volts

Minimum

on Feeder

Voltage Drop Along a Feeder example

http://wiki.powerdistributionresearch.com/index.php?title=File:Voltage_profile_distribution.jpg

Feeder Reality

How do we control Voltage on a Feeder?

Substation Transformer Load Tap Changer (LTC) or Station Voltage Regulator settings

• LTC or Regulator Controller

– Voltage Band Center or Base Voltage

– Voltage Bandwidth (deadband)

– Line Drop Compensation (LDC)

End of Line (EOL) Voltage Control

• Not used by Idaho Power, requires EOL voltmeters, communications and a control system

Why CVR?

Lower voltage by 2-4%

Lower Voltage by 2-4%

1-3% Reduction in: Energy (kWh)

Peak Demand (kW)

Service Voltage

• National Service Voltage Standard (ANSI C84.1)

– “Range A” or Normal Conditions: 114 V-126 V

– Allows ± 5% service voltage bandwidth

• All electric devices operate properly

126 Volts

120 Volts

114 Volts

+5%

0%

-5%

National Standard

Typical Urban Feeder

Urban Feeder

with CVR • Typical Urban

“Feeder” operates in upper half (120-126 V)

• CVR Goal: Operate in lower half (114-120 V)

Typical Urban Feeder Voltage Profile with CVR

114

116

118

120

122

124

126

0 0.5 1 1.5 2 2.5 3 3.5 4

Serv

ice

Vo

lts

Miles from Substation

Typical Service Voltage

Pre CVR

CVR

124 Volts at Substation

120 Volts

Minimum

on Feeder

120 Volts at

Substation 116 Volts

Minimum

on Feeder

What are the challenges of implementing CVR?

• Voltage drop along a feeder may limit potential CVR feeder candidates

• Substation and feeder design/configuration may limit potential CVR candidates

• Ensure the “first customer” as well as the “last customer” are within voltage limits (114-126 volts)

• Complicated feeder layouts make determination of the EOL challenging

• Lots of modeling and load flow analysis and monitoring are necessary

2007 Pilot Study

• Northwest Energy Efficiency Alliance – Distribution Efficiency

Initiative (DEI)

• Lowered Voltage at one substation (Boise Sub) ~ 3%

• End of line feedback • 24 hrs on, 24 hrs off • Results: 1.5% - 2.5% Energy reduction

(kWh) 1.8% - 2.6% Demand reduction

(kW)

NORTHWEST ENERGY EFFICIENCY ALLIANCE DISTRIBUTION EFFICIENCY INITIATIVE PROJECT FINAL REPORT

CVR Data – DEI Pilot Study

NORTHWEST ENERGY EFFICIENCY ALLIANCE DISTRIBUTION EFFICIENCY INITIATIVE PROJECT FINAL REPORT

BOIS T134 Demand (kW) Reduction

NORTHWEST ENERGY EFFICIENCY ALLIANCE DISTRIBUTION EFFICIENCY INITIATIVE PROJECT FINAL REPORT

CVR Energy Reduction

Where does the 1.5 to 2.5 % CVR energy reduction come from (for voltage reduction only)?

• End User: 80% - 90%

• Power System Efficiency Gains: 10% - 20%

Direct benefit for customers:

For typical 1000 kWh/month residential customer:

• Reduce 90-180 kWh/year

2009 CVR at Idaho Power

• Reviewed over 600 feeder circuits for CVR potential – 264 feeder circuits in 81 substations were potential candidates – 30 feeder circuits selected based on extensive load flow analysis

• Implemented CVR at 6 Substations (30 feeder circuits) – 4 in Boise area – 1 in Nampa area – 1 in Pocatello

• ≈29,600 customers • ≈160 MW peak demand • Modified settings in substation transformer equipment • Expenses:

– Engineering studies – Technician time to change substation settings

Load Tap Changer (LTC) Line Drop Compensation settings changes

Typical Substation Transformer LTC Settings

• Base V = 122 volts

• Bandwidth = 3 volts

• R = 2 volts

New CVR Substation Transformer LTC Settings (9

transformers at 6 substations)

• Base V = 118.8 to 119.7 volts

• Bandwidth = 3 volts

• R = 3 to 6 volts

2010/11 CVR at Idaho Power

• Re-examined 69 feeder circuits of the 264 candidates using new load data

– 9 feeder circuits showed promise based on extensive load flow analysis for being potential CVR candidates

• Reviewed feeder circuits for potential candidates with minimal circuit upgrades

– 4 potential CVR candidates identified

• Not yet implemented

Review

• Distribution feeder voltage

• CVR

• DEI study

• Idaho Power CVR to date

Questions?