2011 TECHNICAL REPORT

Green CircuitDistribution Effi ciency Case Studies

EPRI Project Manager K Forsten

ELECTRIC POWER RESEARCH INSTITUTE 3420 Hillview Avenue, Palo Alto, California 94304-1338 PO Box 10412, Palo Alto, California 94303-0813 USA

800.313.3774 650.855.2121 askepri@epri.com www.epri.com

Green Circuits Distribution Efficiency Case Studies

1023518

Final Report, October 2010

DISCLAIMER OF WARRANTIES AND LIMITATION OF LIABILITIES

THIS DOCUMENT WAS PREPARED BY THE ORGANIZATION(S) NAMED BELOW AS AN ACCOUNT OF WORK SPONSORED OR COSPONSORED BY THE ELECTRIC POWER RESEARCH INSTITUTE, INC. (EPRI). NEITHER EPRI, ANY MEMBER OF EPRI, ANY COSPONSOR, THE ORGANIZATION(S) BELOW, NOR ANY PERSON ACTING ON BEHALF OF ANY OF THEM:

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REFERENCE HEREIN TO ANY SPECIFIC COMMERCIAL PRODUCT, PROCESS, OR SERVICE BY ITS TRADE NAME, TRADEMARK, MANUFACTURER, OR OTHERWISE, DOES NOT NECESSARILY CONSTITUTE OR IMPLY ITS ENDORSEMENT, RECOMMENDATION, OR FAVORING BY EPRI.

THE FOLLOWING ORGANIZATIONS PREPARED THIS REPORT:

Electric Power Research Institute (EPRI)

Utility Planning Solutions

University of TexasAustin

NOTE

For further information about EPRI, call the EPRI Customer Assistance Center at 800.313.3774 or e-mail askepri@epri.com.

Electric Power Research Institute, EPRI, and TOGETHERSHAPING THE FUTURE OF ELECTRICITY are registered service marks of the Electric Power Research Institute, Inc.

Copyright 2011 Electric Power Research Institute, Inc. All rights reserved.

This publication is a corporate document that should be cited in the literature in the following manner:

Green Circuits: Distribution Efficiency Case Studies. EPRI, Palo Alto, CA: 2011. 1023518.

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ACKNOWLEDGMENTS

The following organizations prepared this report:

Electric Power Research Institute (EPRI) 942 Corridor Park Blvd. Knoxville, TN 37932

Principal Investigators T. Short D. Brooks B. Arritt W.Sunderman J. Taylor M. Rylander H. Sharma A. Gaikwad J. Smith

Utility Planning Solutions 3416 Bell Ave Everett, WA 98201

Principal Investigator B. Fletcher

University of TexasAustin 24th & Speedway, ENS348 Austin, TX 78712

Principal Investigator M. Grady

This report describes research sponsored by EPRI.

EPRI would like to acknowledge the contributions of the many utility companies and their staff who partnered with EPRI and supported this research:

American Electric Power CenterPoint Energy CPS Energy Consolidated Edison Consumers Energy Dominion Power Duke Energy Entergy

ESB Networks lectricit de France FirstEnergy Hydro Quebec Kansas City Power & Light New York Power Authority Northeast Utilities Pacific Gas & Electric

Public Service Electric & Gas Salt River Project Southern California Edison Southern Company Tennessee Valley Authority United Illuminating Xcel Energy

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Finally, we would like to acknowledge the guidance and leadership of all the advisors and members of EPRIs R&D Program on Transmission & Distribution Efficiency for a Lower Carbon Future (Program 172) for their helpfulness and constructive comments during the last three years.

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ABSTRACT

The Electric Power Research Institute (EPRI) Green Circuits project was a collaborative effort of 22 utilities. The main goal of the project was to evaluate ways to improve distribution efficiency. Modeling, economic evaluations, and field trials formed the core of the research effort. To evaluate efficiency improvements, 66 circuit case studies were modeled and fine-tuned, based on field data. Field trials of voltage optimization were implemented on nine circuits. Detailed advanced metering infrastructure metering data from two circuits also helped to provide information on transformers and secondary circuits.

From simulations and field trials, optimizing voltages to the lower end of the American National Standards Institute range was found to reduce energy consumption from 1% to 3% on most circuits. The optimal efficiency options for a specific circuit depended on circuit characteristics, load placement, circuit issues (like excessive unbalance), economic ranking criteria, and economic assumptions. In some cases, the most economically viable option was just voltage reduction; however, additional improvements were often economically viable also. In other cases, the optimal project included voltage reduction, phase balancing, var optimization, and/or targeted re-conductoring.

Keywords Efficiency Distribution planning Losses Power distribution Voltage optimization

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EXECUTIVE SUMMARY

The Electric Power Research Institute (EPRI) Green Circuits project was a collaborative effort of 22 utilities. The main goal of the project was to evaluate ways to improve distribution efficiency. Modeling, economic evaluations, and field trials formed the core of the research effort. To evaluate efficiency improvements, 66 circuit case studies were modeled and fine-tuned, based on field data. Field trials of voltage optimization were implemented on nine circuits. Detailed advanced metering infrastructure (AMI) metering data from two circuits also helped provide information on transformers and secondaries.

Overall Modeling Results

Sixty-six circuits were modeled as part of the Green Circuit project. Each circuit was modeled in detail from the substation to each customer meter and analyzed, using the long-term dynamic distribution system electrical simulation package OpenDSS. Nearly all of the circuit models were augmented with historical circuit-measurement data that allowed for hourly-resolution simulation of the operation of the circuit for actual load patterns for each hour in a calendar year (8760 hours). All loss sources through both daily and seasonal load changes were found with this high-fidelity representation of the circuits electrical characteristics with the temporal and spatial diversity of the loads. The results of analyzing the 66 circuits point to the following:

Circuit diversity The set of circuits modeled includes a wide variety of circuit characteristics, covering common voltages and urban to rural circuits.

Annual energy losses Total distribution feeder annual energy losses, excluding the substation transformer losses, averaged 3.6% of total consumption for the feeder and ranged from approximately 1.5% to 9%.

Overall losses Losses exceeding 2.52% were reported for 75% of circuits, and 25% of circuits had losses exceeding 4.32%.

Primary line losses Line losses averaged 1.4% of total consumption. Circuit length is a reasonably good predictor of percentage of line losses.

Transformer no-load losses Transformer no-load losses averaged about 1.6% of total energy consumption and ranged from approximately 0.5% to 3.5%. These losses were the most consistent across circuits, depending mainly on transformer age and transformer utilization (connected kVA versus load).

Secondary-line losses Secondary-line losses were very low, averaging 0.3% of consumption, with a maximum of only 0.8%. It should be noted that detailed secondary and service drop lines were available for only a few circuits, such that results are largely based upon the assumptions that were used.

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Peak demand losses At peak load, losses averaged 4.8% of peak demand and ranged from approximately 1.6% to 16.5%. Losses at peak load were predominantly primary line losses. Peak losses exceeding 3.0% were reported for 75% of circuits, and 25% of circuits had losses exceeding 5.8%.

Voltage optimization for energy reduction Optimizing circuit voltages to the lower American National Standards Institute (ANSI) C84.1 range reduced energy consumption on almost all circuits. Using a consistent voltage-reduction approach of controlling an end-of-line primary bus to 118.5 V, the median reduction in energy consumption across all circuits was 2.34%, with upper and lower quartiles of 3.13% and 1.69%.

Phase balancing and reactive power improvements The reduction in losses from improved reactive power support and phase balancing was generally small.

Overall, voltage optimization was the most promising option. It provided the most energy reduction, and it could provide benefit on most circuits. Efficiency improvements depend on circuit characteristics, and reconfigurations may change characteristics.

Economic Optimization

To better evaluate the economics of distribution-efficiency projects, six circuits were selected for extended analysis with the goal of finding the most cost-effective approaches for improving efficiency. For each of these circuits, voltage reduction was modeled, along with several efficiency-improvement options such as phase balancing. In many cases, options helped reduce losses while helping flatten voltage profiles. With flatter voltage profiles, voltage reduction becomes more effective. The costs and economic benefits of each option were calculated, so that economically optimal efficiency options could be selected. From these results, the following lessons were learned:

Economic viability In all six cases, distribution efficiency projects were economically viable. For each circuit, options were available with benefit-to-cost ratios exceeding 3.4, and all had options with levelized life-cycle costs of less than $0.03/kWh. The majority of the energy savings came from voltage reduction.

Lost billing from voltage reduction The economic analysis did not include lost billing from voltage reduction, with the assumption that utilities would recover this by rate adjustments or other regulatory recovery mechanisms.

Highest benefit-to-cost ratios Circuits with the heaviest loading had the highest benefit-to-cost ratios, including higher load densities, 25- and 35-kV class circuits, and bus-regulated circuits. Longer rural, more voltage-limited circuits had lower benefit-to-cost ratios. These guidelines may help utilities target efficiency programs.

Best options The highest-ranking efficiency options for a specific circuit depended on circuit characteristics, load placement, circuit issues (such as excessive unbalance), economic ranking criteria, and economic assumptions. In some cases, the most economically viable option was just voltage reduction; however, additional improvements were often economically viable also. In another scenario, the optimal project included voltage reduction, phase balancing, var optimization, and targeted re-conductoring. Table ES-1 shows optimal options by circuit, based on a strategy of maximizing efficiency as long as the benefit-to-cost ratio exceeded 2.

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Table ES-1 Optimal Options for Each Circuit Based on Maximizing Efficiency

Circuit Option

Levelized Cost

/kWh

Benefit-to-Cost Ratio

Energy Savings

A Phase balancing + var optimization + re-conductoring 3.5 2.9 3.9%

B Phase balancing 0.6 17.0 3.6%

C Phase balancing + var optimization 2.4 3.8 2.3%

D Phase balancing + var optimization 2.1 4.7 1.3%

E Voltage regulators 3.9 2.5 1.9%

F Voltage regulators 0.6 16.2 2.6%

Efficiency approach Because each circuit was different, improvement options should be targeted to the specific circuits needs. If phases are unbalanced, the focus should be on tap phasing to address the issue. It is important to consider the load placement. Maximum benefit occurs if voltages are flat and controlled at key load centers. This can affect where capacitors or regulators are located. It is often beneficial to try efficiency options in the following order: phase balancing by rephasing taps, simple reconfigurations to balance phases or loading among sections, capacitor control or placement changes, addition of regulators, and then targeted re-conductoring. Fixing problem transformers/secondaries is another option.

Transformer and Secondary Detailed Case Study

Because utilities normally did not have transformer loss information or secondary circuit models, accurately evaluating losses and voltage drops in secondaries and transformers was a key challenge. One utility had good secondary models along with advanced metering data. Some of the transformers also had metering to allow EPRI to evaluate losses and voltage drops with both measurements and detailed simulations. Some of the key findings from this analysis are:

Secondary line losses were generally low, but they were higher than the generic models used for most circuits. Findings from the overall simulations showed annual secondary line losses of 0.31%. In more precise modeling of four secondary systems, average losses were 0.76%. From estimates of AMI metering data from two circuits (44 secondaries total), average secondary losses were 0.72% on one circuit and 0.87% on another.

Based on metering on transformer secondaries and customers, voltage drops across secondaries averaged 0.33 V on a set of 269 customers. At peak load, 85% of secondary drops were less than 2 V. Transformer voltage drops were typically less than 1 V, and peak voltage drops between 0.5 and 3 V. Eighty percent of peak transformer voltage drops were less than 3 V. The total voltage drop across the transformer and secondaries averaged 1.0 V, and only 1% of the voltage drops were above 4.2 V.

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As with other circuits, circuit voltage measurements from metering data ranged on the high side of the ANSI C84.1 range. On two circuits analyzed, the median customer voltage was close to 122 V. Even at peak load, voltages were generally high, with median customer voltages above 121 V on both circuits. This leaves significant room to reduce voltages.

Voltage Optimization Field Trials

Field trials of voltage reduction were evaluated at several utilities to analyze the effectiveness of voltage optimization on improving end-use efficiency, reducing overall energy consumption, and reducing reactive power. Nine circuits at four utilities were operated on a test program to evaluate reduced-voltage operating modes. The monitoring periods of the nine circuits ranged from 11 to 24 months. Most of the circuits were in the southeastern United States. Reduced voltage was evaluated by alternating daily between a normal-voltage mode and a reduced-voltage mode. Voltage was controlled with local controllers controlling voltage regulators or load tap-changing (LTC) transformers. Several findings from analysis of the results include:

Load decreased by 1.6% to 2.7% for substation voltages reduced by 2.0% to 4.0% (see Figure ES-1). In terms of a conservation voltage reduction (CVR) factor, the percent change in load for a 1% change in voltage generally ranges from 0.6 to 0.8.

Reactive power responds even more strongly to voltage reduction than real power. Reactive power CVR factors exceeded 4 on two circuits with AMI metering that were capable of measuring reactive power.

A statistical regression approach using measurements from one or more circuits with comparable load patterns works well to normalize results and more precisely evaluate the impact of voltage on load.

Voltage reduction is most effective in the summer and least effective in the winter, when more thermostatically controlled heating load (constant energy) is present.

Average energy reductions for the EPRI tests circuits were similar in range to a previous study by the Northwest Energy Efficiency Alliance (NEEA). This is significant because the climate and load patterns in the northwestern United States differ from the EPRI circuits, which were primarily in the Southeast.

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0 1 2 3 4

0

1

2

3

4

Voltage reduction, percent

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redu

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Figure ES-1 Comparison of Energy Reduction and Confidence Intervals for Several Circuits

Future Work

Project results have shown that the distribution system can be a significant resource for reducing energy consumption, particularly when voltage optimization is combined with other distribution improvements. Based on these considerations, some of the key industry needs for distribution efficiency are:

Regulatory constraints Billing is a significant roadblock to widespread implementation of voltage optimization. Reduced end-use consumption lowers customer kilowatt hour billing. To offset that lost billing, changes in billing rates or structure are needed. The industry needs to do more work to investigate options to remove this roadblock.

Load models Better models of the response of loads to voltage will help utilities target voltage-optimization projects and claim financial credits for implementing distribution efficiency projects. Better models will also allow predictions of future benefits of voltage optimization.

Field trials The field trials consisted of nine circuits, primarily in the southeastern United States. More field trials would help utilities in other areas better quantify efficiency gains. Implementation of different voltage control and volt-var control systems will help determine how much improvement is possible with more sophisticated systems.

Planning Efficiency needs include guidelines to determine conductor loading, substation sizing and locations, and maximum feeder lengths and voltage drops. Tools are needed to optimize transformer and secondary based on cost, voltage drop, and loading.

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Modeling There is a need to bring annual 8760-hour simulation capabilities of OpenDSS and other advanced features to industry standard tools. Several other modeling needs have been identified, including better transformer and secondary data and modeling.

AMI More work is needed to determine how to best use AMI data for efficiency improvements.

Optimization There may be a need for tools to make it easier for utilities to perform economic evaluations of efficiency options in order to optimize efficiency.

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CONTENTS

1 BACKGROUND AND FINDINGS...........................................................................................1-1 Green Circuits Project and Objectives ..................................................................................1-2 Distribution Efficiency............................................................................................................1-2 Organization of This Report ..................................................................................................1-4

2 ANALYTICAL FRAMEWORK AND MODELING RESULTS.................................................2-1 Introduction ...........................................................................................................................2-1 Analytical Framework ............................................................................................................2-2

Modeling Software OpenDSS........................................................................................2-5 Load Modeling ..................................................................................................................2-6 Service Transformer Modeling .........................................................................................2-8 Capacitor Modeling.........................................................................................................2-11 Voltage-Regulation Modeling .........................................................................................2-13 Service-Line Modeling ....................................................................................................2-13 Load Allocations and Load Variation ..............................................................................2-14

General Characteristics.......................................................................................................2-19 Loss Characteristics ............................................................................................................2-33 Improvement Options..........................................................................................................2-42 Comparing Detailed Modeling to Peak-Case Models..........................................................2-53 Conclusions.........................................................................................................................2-58

3 EXTENDED ANALYSIS AND ECONOMIC COMPARISONS................................................3-1 Analysis Approach.................................................................................................................3-2

Financial Factors ..............................................................................................................3-4 Energy Savings Analysis.......................................................................................................3-7 Demand Reduction Analysis .................................................................................................3-8 Economic Analysis ................................................................................................................3-9

Economic Acceptability.....................................................................................................3-9

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Economic Acceptability With Voltage Reduction Only at Peak ......................................3-12 Economic Parameter Sensitivity.....................................................................................3-13

Application of Results..........................................................................................................3-17 Individual Case Analysis .....................................................................................................3-18

Circuit A ..........................................................................................................................3-18 Circuit F ..........................................................................................................................3-26

Summary and Conclusions .................................................................................................3-35

4 CASE STUDIES .....................................................................................................................4-1 Reactive Power Control Case Study .....................................................................................4-1

Circuit 1 Base Case..........................................................................................................4-1 Ideal Var Case (Circuit 1).............................................................................................4-3 Capacitor-Control Case (Circuit 1)...............................................................................4-3 Results.........................................................................................................................4-3

Circuit 2 Base Case..........................................................................................................4-5 Results.........................................................................................................................4-6

Summary ..........................................................................................................................4-8 Distribution Transformer Impacts ..........................................................................................4-9

Department of Energy Transformer Efficiency Standards ................................................4-9 Comparison of DOE Efficiency Standard Levels to Green Circuits Utility Data..............4-10 Transformer Efficiency Versus Loading..........................................................................4-12

Voltage Optimization Case Study........................................................................................4-14 Voltage Profiles and Expected Energy and Demand Reductions ..................................4-18 Voltage Regulator Settings.............................................................................................4-21

Comparison of Voltage Reduction Approaches ..................................................................4-23 LTC With Remote Voltage Feedback .............................................................................4-24 LTC With Line-Drop Compensation (LDC) .....................................................................4-25 LTC and Remote Feeder Regulators Using Voltage Feedback .....................................4-27 Feeder Head Single-Phase Voltage Regulators With Remote Voltage Feedback.........4-29 Simple Volt-Var Optimization..........................................................................................4-30 Summary ........................................................................................................................4-32

Impacts on the Substation Transformer ..............................................................................4-33 Analysis of Cases ...........................................................................................................4-35 Summary ........................................................................................................................4-37

Conservation Voltage Reduction Factor Sensitivity ............................................................4-37

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Power Factor Sensitivity......................................................................................................4-39

5 TRANSFORMERS AND SECONDARIES .............................................................................5-1 Secondary Circuit Modeling With Measurements .................................................................5-2

Secondary Circuit Models.................................................................................................5-2 Circuit #1......................................................................................................................5-5 Circuit #2......................................................................................................................5-9 Circuit #3....................................................................................................................5-11 Circuit #4....................................................................................................................5-13

Secondary Analysis Simulation Approaches ..................................................................5-15 Secondary Voltages...................................................................................................5-18

Secondary Data Analysis ....................................................................................................5-22 Secondary Line Losses ..................................................................................................5-23 Transformer Load Losses...............................................................................................5-26 Secondary Voltages .......................................................................................................5-29 Secondary Voltage Drops...............................................................................................5-36 Combined Transformer and Secondary Voltage Drops\.................................................5-44

Summary.............................................................................................................................5-46

6 VOLTAGE OPTIMIZATION FIELD TRIAL RESULTS ...........................................................6-1 Background on Voltage Optimization ....................................................................................6-1 Study Approach.....................................................................................................................6-6 Regression Approach for Normalization................................................................................6-7 Overall Results ....................................................................................................................6-13 Comparisons by Month .......................................................................................................6-15 Comparisons by Day of the Week.......................................................................................6-19 Hourly Results .....................................................................................................................6-20 Comparison to NEEA Results .............................................................................................6-24 Impact on Reactive Power ..................................................................................................6-26 Customer Complaints From Voltage Reduction ..................................................................6-27 Analysis of AMI Data ...........................................................................................................6-27 Reactive Power Impacts Measured by AMI ........................................................................6-45 Summary and Conclusions .................................................................................................6-48

7 SUMMARY AND FUTURE WORK.........................................................................................7-1

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A EXAMPLE CIRCUIT ANALYSIS .......................................................................................... A-1 Circuit Background............................................................................................................... A-1 Model Development and Base-Case Analysis ..................................................................... A-4

Base-Case Results.......................................................................................................... A-7 Efficiency Options Assessments .......................................................................................... A-8

Voltage Optimization ....................................................................................................... A-9 Voltage Optimization Modeling of LTC Set-Point Variation ........................................ A-10 Phase Balancing............................................................................................................ A-15 Re-Conductoring ........................................................................................................... A-17 Ideal Var Optimization ................................................................................................... A-19 Capacitor Control........................................................................................................... A-20

Summary............................................................................................................................ A-22

B ALTERNATE METHODOLOGY FOR EFFICIENCY ANALYSIS......................................... B-1 Distribution System Factors ................................................................................................. B-2 Distribution System Modeling............................................................................................... B-9

Modeling Overview .......................................................................................................... B-9 System Maps .............................................................................................................. B-9 System Load-Flow Model ......................................................................................... B-10

System Analysis Process .............................................................................................. B-13 Process Steps........................................................................................................... B-13 Distribution System Efficiency Thresholds................................................................ B-16 Distribution System Kvar Analysis ............................................................................ B-18 Average Voltage Impact and Analysis ...................................................................... B-19 Financial Factors....................................................................................................... B-23

Distribution Efficiency Study Reporting ......................................................................... B-24 Example Distribution Efficiency Study ........................................................................... B-27

Overview of Distribution System............................................................................... B-27 Summary of Findings and Recommendations .......................................................... B-28 Available System Data Sources................................................................................ B-29 Feeder Topology Maps of Service Area and Location of Substation........................ B-30 Existing Metering Capability Evaluation.................................................................... B-30 Feeder kW and kvar Annual Load Profiles ............................................................... B-31 Customer Load Characteristics, Heating and Cooling Zones, and VO Factors........ B-33 Assessment of Existing Transformer/Secondary Voltage Drops .............................. B-34

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Compliance Threshold Assessment for Existing and Improved Cases .................... B-35 Non-Compliance Violations Identification on Circuit Maps for Existing Case ........... B-36 Average Distribution Transformer Utilization Assessment........................................ B-37 Assessment of Customer Voltage Compliance with ANSI Voltage Standard ........... B-37 System Improvement Investment Cost Assumptions ............................................... B-38 Description of Recommended System Improvements.............................................. B-39 Location of Recommended Improvements on Maps ................................................ B-40 Average Voltage Analysis and Loss Impacts............................................................ B-40 Existing System Average Voltage Calculation .......................................................... B-42 Improved System Average Voltage Calculation........................................................ B-42 Economic Factors and Evaluation Assumptions....................................................... B-44 Economic Analysis.................................................................................................... B-45 Economic Data Given ............................................................................................... B-45 Summary Exhibits of Benefits and Costs.................................................................. B-47

Bibliography ....................................................................................................................... B-50

C EXTENDED CASE STUDIES ............................................................................................... C-1 Circuit B................................................................................................................................ C-1 Circuit C ............................................................................................................................... C-8 Circuit D ............................................................................................................................. C-13 Circuit E.............................................................................................................................. C-19

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LIST OF FIGURES

Figure 2-1 General Process for Developing Green Circuits Base-Case Model .........................2-4 Figure 2-2 Representation of a ZIP Load ................................................................................2-7 Figure 2-3 Simplified Representation of an OpenDSS Transformer Model ...............................2-9 Figure 2-4 Temperature Control for Summer Switching (May 15 to September 15)................2-12 Figure 2-5 Temperature Control for Non-Summer Switching (September 15 to May 15)........2-12 Figure 2-6 Example of LTC Operation of the Model Verified Against the Measured Bus

Voltage .............................................................................................................................2-13 Figure 2-7 Example of Estimating Load Usage Based on AMI Data .......................................2-15 Figure 2-8 Example of Load Scaling........................................................................................2-16 Figure 2-9 Example of Normalized Load Shape ......................................................................2-16 Figure 2-10 Example of Verifying Simulated Phase Current to Measured Phase Current ......2-18 Figure 2-11 Example of Verifying Simulated Bus Power to Measured Bus Power ..................2-18 Figure 2-12 Example of Verifying Simulated Voltage to Measured Voltage ............................2-19 Figure 2-13 Circuits by Voltage and Distance from the Substation .........................................2-21 Figure 2-14 Number of Customers per Circuit .........................................................................2-22 Figure 2-15 Circuit Load Factors .............................................................................................2-23 Figure 2-16 Load Densities......................................................................................................2-24 Figure 2-17 Load versus Connected kVA ................................................................................2-25 Figure 2-18 Residential Load as a Percentage of Connected kVA..........................................2-26 Figure 2-19 Unbalance Versus Load Current ..........................................................................2-27 Figure 2-20 Circuit AA One-Line to Illustrate the Cause of the Unbalanced Load Current......2-28 Figure 2-21 Average Power Factors by Circuit ........................................................................2-29 Figure 2-22 Peak Load and Total Connected Capacitance .....................................................2-29 Figure 2-23 Statistical Distributions of the Minimum Primary Design Voltage .........................2-31 Figure 2-24 Minimum Primary Design Voltage Versus Simulated Minimum Primary

Voltage .............................................................................................................................2-31 Figure 2-25 Statistical Distributions of the Maximum Secondary Design Voltage Drop...........2-32 Figure 2-26 Maximum Primary and Secondary Design Voltage Drop for Two Utilities............2-32 Figure 2-27 Percent Losses by Location .................................................................................2-34 Figure 2-28 Circuit Loss Breakdowns in Average Percentage ................................................2-35 Figure 2-29 Circuit Loss Breakdowns in Average kW..............................................................2-36 Figure 2-30 Circuit Losses at Peak Load.................................................................................2-37

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Figure 2-31 Circuit Losses at Peak Load in kW.......................................................................2-38 Figure 2-32 Peak Versus Average Losses ..............................................................................2-39 Figure 2-33 Average Losses by System Voltage.....................................................................2-39 Figure 2-34 Losses by Load Density .......................................................................................2-40 Figure 2-35 Losses by Circuit Length ......................................................................................2-41 Figure 2-36 Losses by Number of Customers .........................................................................2-41 Figure 2-37 Reduction in Line Losses With Ideal Var Improvement ........................................2-42 Figure 2-38 Reduction in Line Losses with Ideal Phase Balancing .........................................2-43 Figure 2-39 Re-Conductoring Impact on Line Losses .............................................................2-44 Figure 2-40 Example of OpenDSS Plot to Identify Sections With the Highest Line Losses ....2-45 Figure 2-41 Reduction in Energy Supplied With Voltage Optimization....................................2-48 Figure 2-42 Reduction in Average Energy With Voltage Optimization (Average kW)..............2-49 Figure 2-43 Circuit Diagram to Illustrate Reach of Voltage Regulation Monitoring Point.........2-50 Figure 2-44 Reduction in Peak Loading With Voltage Optimization (kW)................................2-51 Figure 2-45 Comparison of Reduction in Energy With Reduction in Peak Demand................2-52 Figure 2-46 Average Primary Voltage Prior to Reduction Versus Reduction in Energy ..........2-53 Figure 2-47 Comparing Estimated Loss Factors to Loss Factors From Detailed Modeling

(C-Factor = 0.7)................................................................................................................2-56 Figure 2-48 Comparing Estimated Loss Factors Using the Gustafson-Baylor Model to

Loss Factors From Detailed Modeling .............................................................................2-57 Figure 2-49 Percent Losses From Detailed Modeling and Peak-Case Modeling (C-Factor

= 0.92) ..............................................................................................................................2-58 Figure 3-1 Acceptable Efficiency Projects With Respect to Levelized Cost.............................3-11 Figure 3-2 BCR (Linear Curve Fit) Relationship With Peak Demand ......................................3-16 Figure 3-3 LC (Inverse Curve Fit) Relationship With Peak Demand........................................3-16 Figure 3-4 BCR (Linear) and LC (Power) Relationship With Average Hourly Demand ...........3-17 Figure 3-5 Circuit A Map ..........................................................................................................3-19 Figure 3-6 Peak Hour Bus Voltage versus Distance From Substation ....................................3-20 Figure 3-7 Annual Energy Saved and Peak Demand Reduction.............................................3-23 Figure 3-8 Economic Acceptability Shown by Benefit-Cost Ratio and Levelized Cost for

Efficiency Projects............................................................................................................3-25 Figure 3-9 Circuit Map .............................................................................................................3-27 Figure 3-10 Base Case Peak Hour Bus Voltage versus Distance From Substation................3-29 Figure 3-11 Option VR Peak Hour Bus Voltage w.r.t Distance From Substation.....................3-29 Figure 3-12 Annual Energy Saved and Peak Demand Reduction...........................................3-31 Figure 3-13 Economic Acceptability Shown by Benefit-Cost Ratio and Levelized Cost for

Efficiency Projects............................................................................................................3-33 Figure 4-1 Circuit 1 One-Line Diagram ......................................................................................4-2 Figure 4-2 Efficiency Comparison Summary Graph ..................................................................4-5 Figure 4-3 Circuit 2 One-Line Diagram ......................................................................................4-6

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Figure 4-4 Efficiency Comparison Summary Graph ..................................................................4-7 Figure 4-5 Meter Data of Reactive Power..................................................................................4-8 Figure 4-6 Meter Data of Real Power ........................................................................................4-9 Figure 4-7 Green Circuits Old/New Transformer Efficiencies and DOE Standard-

Efficiency Transformers at Various Nameplate Ratings...................................................4-12 Figure 4-8 Transformer Efficiency Versus Loading..................................................................4-14 Figure 4-9 Circuit A ..................................................................................................................4-15 Figure 4-10 Circuit B ................................................................................................................4-16 Figure 4-11 Annual Profile of Load and Losses on Circuit A by Week ....................................4-17 Figure 4-12 Hourly Profile of Load and Losses on Circuit A ....................................................4-18 Figure 4-13 Voltage Profile Along Circuit A .............................................................................4-19 Figure 4-14 Voltage Profile Along Circuit B .............................................................................4-19 Figure 4-15 Voltage Profile Along Circuit A .............................................................................4-20 Figure 4-16 Voltage Profile Along Circuit B .............................................................................4-20 Figure 4-17 One-Line Diagram of the Substation/Feeders Under Study .................................4-24 Figure 4-18 Voltage Profile Resulting From the Remote Voltage Feedback With the LTC .....4-25 Figure 4-19 Voltage Profile Resulting From the Line Drop Compensation Approach to

Voltage Optimization ........................................................................................................4-27 Figure 4-20 Voltage Profile at Peak Hour for the Case With Multiple Remote (Feeder)

Regulators and the LTC Operating on Remote Voltage Feedback..................................4-28 Figure 4-21 Locations of the Three Remote Feeder Regulators and the LTC Feedback

Bus ...................................................................................................................................4-29 Figure 4-22 Voltage Profile Plot for the Case of Three Single-Phase Regulators at the

Head of Each of the Four Circuits ....................................................................................4-30 Figure 4-23 Voltage Profile Resulting From a Volt-Var Optimization Scheme.........................4-32 Figure 4-24 Substation With Four Feeders Modeled in Detail .................................................4-34 Figure 4-25 Example Peak Hour Demand Versus CVR Factor ...............................................4-38 Figure 4-26 Example Annual Consumption Versus CVR Factor .............................................4-39 Figure 4-27 Variable Power Factor ..........................................................................................4-40 Figure 4-28 Hourly End-Use Reactive Load ............................................................................4-40 Figure 5-1 Secondary Circuit #1 One-Line Diagram..................................................................5-5 Figure 5-2 Measured Customer Demands of Circuit #1.............................................................5-6 Figure 5-3 Measured Demand at the Service Transformer Secondary of Circuit #1 .................5-6 Figure 5-4 Measured Losses on Circuit #1 ................................................................................5-7 Figure 5-5 Transformer Secondary Bus Voltage of Circuit #1 ...................................................5-7 Figure 5-6 Measured-Versus-Model Secondary Voltage Drop of Circuit #1 ..............................5-8 Figure 5-7 Measured-Versus-Model Line Losses for Circuit #1.................................................5-9 Figure 5-8 Secondary Circuit #2 One-Line Diagram..................................................................5-9 Figure 5-9 Customer Demand (kW) for Circuit #2 ...................................................................5-10 Figure 5-10 Measured-Versus-Model Secondary Voltage Drop for Circuit #2.........................5-11

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Figure 5-11 Measured-Versus-Model Line Losses for Circuit #2.............................................5-11 Figure 5-12 Secondary Circuit #3 One-Line Diagram..............................................................5-12 Figure 5-13 Measured-Versus-Model Secondary Voltage Drop for Circuit #3.........................5-12 Figure 5-14 Measured-Versus-Model Line Losses for Circuit #3.............................................5-13 Figure 5-15 Secondary Circuit #4 One-Line Diagram..............................................................5-14 Figure 5-16 Measured-Versus-Model Secondary Voltage Drop for Circuit #4.........................5-15 Figure 5-17 Model Comparison of Customer Demand Variation Over a Sample Week ..........5-16 Figure 5-18 Minimum Non-Coincident Bus Voltages (Circuit #1).............................................5-19 Figure 5-19 Average Annual Bus Voltages (Circuit #1) ...........................................................5-19 Figure 5-20 Minimum Non-Coincident Bus Voltages (Circuit #2).............................................5-20 Figure 5-21 Average Annual Bus Voltages (Circuit #2) ...........................................................5-20 Figure 5-22 Minimum Non-Coincident Bus Voltages (Circuit #3).............................................5-21 Figure 5-23 Average Annual Bus Voltages (Circuit #3) ...........................................................5-21 Figure 5-24 Minimum Non-Coincident Bus Voltages (Circuit #4).............................................5-22 Figure 5-25 Average Annual Bus Voltages (Circuit #4) ...........................................................5-22 Figure 5-26 Secondary Line Loss Probability Distributions for the Monitored Subset of

Circuit A............................................................................................................................5-23 Figure 5-27 Secondary Line Loss Probability Distributions for the Monitored Subset of

Circuit B............................................................................................................................5-24 Figure 5-28 Secondary Line Losses Versus Different Factors for the Monitored Subset of

Circuit A............................................................................................................................5-25 Figure 5-29 Secondary Line Losses Versus Different Factors for the Monitored Subset of

Circuit B............................................................................................................................5-26 Figure 5-30 Transformer Load Loss Distributions for the Monitored Subset of Circuit A.........5-27 Figure 5-31 Transformer Load Loss Distributions for the Monitored Subset of Circuit B.........5-27 Figure 5-32 Transformer Load Losses Versus Different Factors for the Monitored Subset

of Circuit A........................................................................................................................5-28 Figure 5-33 Transformer Load Losses versus different Factors for the Monitored Subset

of Circuit B........................................................................................................................5-29 Figure 5-34 Meter Voltage Probability Distributions for Circuit A .............................................5-30 Figure 5-35 Meter Voltage Probability Distributions for Circuit B .............................................5-30 Figure 5-36 Meter Voltage Profiles ..........................................................................................5-31 Figure 5-37 Secondary Voltage Profiles ..................................................................................5-32 Figure 5-38 Meter and Transformer Secondary Voltage Probability Distributions for

Circuit A............................................................................................................................5-33 Figure 5-39 Meter and Transformer Secondary Voltage Probability Distributions for

Circuit B............................................................................................................................5-33 Figure 5-40 Meter Voltage Probability Distributions at Peak Load for Circuit A.......................5-34 Figure 5-41 Meter Voltage Probability Distributions at Peak Load for Circuit B.......................5-35 Figure 5-42 Meter Voltage Profile at Peak Load for Circuit A ..................................................5-35

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Figure 5-43 Secondary Voltage Drop Probability Distributions for the Metered Subset of Circuit A............................................................................................................................5-36

Figure 5-44 Secondary Voltage Drop Probability Distributions for the Metered Subset of Circuit B............................................................................................................................5-37

Figure 5-45 Peak-Load Secondary Voltage Drop Probability Distributions for the Metered Subset of Circuit A ...........................................................................................................5-37

Figure 5-46 Peak-Load Secondary Voltage Drop Probability Distributions for the Metered Subset of Circuit B ...........................................................................................................5-38

Figure 5-47 Voltage Drops Versus Different Factors for the Monitored Subset of Circuit A ....5-39 Figure 5-48 Voltage Drops Versus Different Factors for the Monitored Subset of Circuit B ....5-40 Figure 5-49 Transformer Voltage Drop Probability Distributions for the Metered Subset of

Circuit A............................................................................................................................5-41 Figure 5-50 Transformer Voltage Drop Probability Distributions for the Metered Subset of

Circuit B............................................................................................................................5-41 Figure 5-51 99th Percentile Transformer Voltage Drop Probability Distributions for the

Metered Subset of Circuit A .............................................................................................5-42 Figure 5-52 99th Percentile Transformer Voltage Drop Probability Distributions for the

Metered Subset of Circuit B .............................................................................................5-42 Figure 5-53 Transformer Voltage Drops Versus Loading for the Monitored Subset of

Circuit A............................................................................................................................5-43 Figure 5-54 Transformer Voltage Drops Versus Loading for the Monitored Subset of

Circuit B............................................................................................................................5-44 Figure 5-55 Transformer and Secondary Voltage Drops Versus Loading for the

Monitored Subset of Circuit A ..........................................................................................5-45 Figure 5-56 Transformer and Secondary Voltage Drops Versus Loading for the

Monitored Subset of Circuit B ..........................................................................................5-45 Figure 6-1 Energy Savings Versus Voltage Reduction for the NEEA Study Pilot Feeders........6-2 Figure 6-2 Change in Reactive Power in the NEEA Study Homes............................................6-3 Figure 6-3 Impact of Voltage and Torque on an Example Motor ...............................................6-5 Figure 6-4 Tests of a Typical Modern 3-kW Air Conditioner ......................................................6-6 Figure 6-5 Temperature Normalization and Comparable-Circuit Normalization ........................6-8 Figure 6-6 Test Circuits Compared to Comparison Circuits.......................................................6-9 Figure 6-7 Circuit A Comparisons to Other Circuits.................................................................6-11 Figure 6-8 Example Load and Voltage Profile .........................................................................6-12 Figure 6-9 Comparison of Energy Reduction and Confidence Intervals for Several

Circuits .............................................................................................................................6-14 Figure 6-10 Comparison of Energy Reduction and Confidence Intervals for Several

Circuits .............................................................................................................................6-15 Figure 6-11 Monthly Comparisons of Average Power Consumption With and Without

Voltage Reduction............................................................................................................6-16 Figure 6-12 Reduction in Average Power Consumption With Voltage Reduction ...................6-17 Figure 6-13 Percent Reduction in Average Power Consumption With Voltage Reduction ......6-18

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Figure 6-14 CVR Factor by Month ...........................................................................................6-19 Figure 6-15 Weekly Comparisons of Average Power Consumption With and Without

Voltage Reduction............................................................................................................6-20 Figure 6-16 Hourly Comparisons of Average Power Consumption With and Without

Voltage Reduction............................................................................................................6-21 Figure 6-17 Reduction in Average Power Consumption With Voltage Reduction ...................6-22 Figure 6-18 Percent Reduction in Average Power Consumption With Voltage Reduction ......6-23 Figure 6-19 CVR Factor by Hour of the Day............................................................................6-24 Figure 6-20 Comparison of Voltage Reduction on EPRI Feeders and NEEA Feeders ...........6-25 Figure 6-21 Comparison of CVR Factors on EPRI Feeders and NEEA Feeders ....................6-25 Figure 6-22 Normalized Var Comparisons for Circuit A...........................................................6-27 Figure 6-23 Statistical Distribution of Customer Voltages by Circuit........................................6-28 Figure 6-24 Energy Usage Profiles by Customer Class With Energy Reduction From

Voltage Reduction for Circuit A ........................................................................................6-30 Figure 6-25 Clustering of Non-Residential Meters for Circuit A ...............................................6-31 Figure 6-26 Clustering of Non-Residential Meters for Circuit A After Removing Lighting

Load .................................................................................................................................6-32 Figure 6-27 Energy Reduction From Voltage Reduction for the 20 Largest Customers on

Circuit A............................................................................................................................6-33 Figure 6-28 Profiles and Energy Reduction From Voltage Reduction for the 20 Largest

Customers on Circuit A ....................................................................................................6-34 Figure 6-29 Energy Reduction From Voltage Reduction for Two Residential Rate

Classes on Circuit A.........................................................................................................6-35 Figure 6-30 Daily Profile Grouping With Energy Reduction From Voltage Reduction for

Residential Customers on Circuit A .................................................................................6-36 Figure 6-31 Daily Profile Grouping With Energy Reduction From Voltage Reduction by

Season for Residential Customers on Circuit A ...............................................................6-37 Figure 6-32 Customer Class and Voltage Reduction for AMI Subset G ..................................6-38 Figure 6-33 Power Factor and Voltage Reduction for AMI Subset G ......................................6-39 Figure 6-34 Power Factor Ranges and Voltage Reduction for AMI Subset G.........................6-40 Figure 6-35 Customer Class and Voltage Reduction for AMI Subset H ..................................6-41 Figure 6-36 Customer Size and Voltage Reduction for AMI Subset H ....................................6-42 Figure 6-37 Power Factor Ranges and Voltage Reduction for AMI Subset H .........................6-43 Figure 6-38 Clusters by Watt and Var Profiles and Voltage Reduction for AMI Subset H.......6-44 Figure 6-39 Daily Reactive Power Averages for AMI Subset G...............................................6-45 Figure 6-40 Distributions of Daily Reactive Power Averages for AMI Subset G......................6-46 Figure 6-41 CVR Var Factors by Customer Billing Class for AMI Subset G............................6-47 Figure 6-42 CVR Var Factors by Rolling Month for AMI Subset G ..........................................6-47

Figure A-1 Circuit One-Line (Power Plot Thicker Lines Indicate Higher Power Flow) ........... A-2 Figure A-2 Plot of the Circuits Step-Down Transformers ......................................................... A-3 Figure A-3 Plot of the Customers Service Transformers ......................................................... A-4

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Figure A-4 Model Development Steps for Example Circuit....................................................... A-5 Figure A-5 Modeled Verses Measured Line Currents............................................................... A-6 Figure A-6 Modeled Verses Measured Bus Power Levels ....................................................... A-7 Figure A-7 Base-Case Peak Loss Breakdown.......................................................................... A-8 Figure A-8 Base Case Annual Loss Breakdown....................................................................... A-8 Figure A-9 Voltage Optimization Remote Regulation ............................................................. A-10 Figure A-10 Substation Bus Voltage Comparison With Measured and Model Results

(The Model Included the In-the-Field LTC Set-Point Variation) .................................... A-11 Figure A-11 Simulated Base Case Compared With Measured Voltages................................ A-12 Figure A-12 Substation Bus Voltage Comparison With Measured and Voltage-

Optimization Model Results ............................................................................................ A-14 Figure A-13 Phase-Balance Case Peak Currents .................................................................. A-16 Figure A-14 Identified Line Sections With the Highest Losses ............................................... A-18 Figure A-15 Conductors That Were Re-Conductored............................................................. A-19 Figure A-16 Capacitor Placement........................................................................................... A-21 Figure A-17 Efficiency Comparison Summary Graph ............................................................. A-23 Figure A-18 In-the-Field Voltage Regulation Simulation Results Compared to the

Measured Voltage ........................................................................................................... A-25 Figure A-19 Voltage Optimization Simulation Results Compared to the Measured

Voltage ............................................................................................................................ A-25 Figure B-1 Map of Existing Feeder Layout for Example-Feeder............................................. B-30 Figure B-2 Annual kW Load Profile for Example Feeder ........................................................ B-31 Figure B-3 Annual kvar Load Profile for Example Feeder ...................................................... B-31 Figure B-4 Annual 30 Customer kW Load Profile for Example Feeder................................... B-32 Figure B-5 Annual 30 Customer pf Load Profile for Example Feeder..................................... B-32 Figure B-6 Distribution Transformer/Secondary Max Voltage Drops...................................... B-35 Figure B-7 Location of Primary Feeder Volts Less Than 120 V at Peak Loads...................... B-36 Figure B-8 Lowest Service Voltage for Each Distribution Transformer/Secondary................. B-37 Figure B-9 Recommended System Improvements ................................................................. B-40 Figure C-1 Circuit Map Indicating Capacitors () and Regulators () ....................................... C-2 Figure C-2 Peak Hour Bus Voltage versus Distance From Substation..................................... C-2 Figure C-3 Annual Energy Saved and Peak Demand Reduction ............................................. C-4 Figure C-4 Economic Acceptability Shown by Benefit-Cost Ratio and Levelized Cost for

Efficiency Projects............................................................................................................. C-6 Figure C-5 Circuit Map.............................................................................................................. C-8 Figure C-6 Peak Hour Bus Voltage w.r.t Distance From Substation......................................... C-9 Figure C-7 Annual Energy Saved and Peak Demand Reduction ........................................... C-11 Figure C-8 Economic Acceptability Shown by Benefit-Cost Ratio and Levelized Cost for

Efficiency Projects........................................................................................................... C-12 Figure C-9 Peak Hour Bus Voltage versus Distance From Substation................................... C-13

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Figure C-10 Circuit Map Indicating Capacitors ....................................................................... C-14 Figure C-11 Annual Energy Saved and Peak Demand Reduction ......................................... C-16 Figure C-12 Economic Acceptability Shown by Benefit-Cost Ratio and Levelized Cost for

Efficiency Projects........................................................................................................... C-18 Figure C-13 Circuit Map Indicating Capacitors () and Step-Down Transformer ().............. C-20 Figure C-14 Base Case Peak Hour Bus Voltage w.r.t Distance From Substation.................. C-22 Figure C-15 Option VR Peak Hour Bus Voltage w.r.t Distance From Substation................... C-22 Figure C-16 Annual Energy Saved and Peak Demand Reduction ......................................... C-23 Figure C-17 Economic Acceptability Shown by Benefit-Cost Ratio and Levelized Cost for

Efficiency Projects........................................................................................................... C-25

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LIST OF TABLES

Table 2-1 5-kV Class Transformer Losses ..............................................................................2-10 Table 2-2 15-kV Class Transformer Losses ............................................................................2-10 Table 2-3 15-kV Class Transformer Losses (19862006) .......................................................2-11 Table 2-4 Distribution Circuit Loss Statistics, Percent .............................................................2-33 Table 2-5 Distribution Circuit Loss Statistics Weighted by Load, Percent ...............................2-34 Table 2-6 Average Energy Savings From Voltage Optimization by Component .....................2-47 Table 3-1 Extended Case Study Circuits ...................................................................................3-1 Table 3-2 Average Marginal Cost for Several Green Circuit Participants..................................3-4 Table 3-3 Economic Parameters Used to Determine BCR and LC ...........................................3-5 Table 3-4 Construction Cost Estimates .....................................................................................3-6 Table 3-5 Efficiency Project Annual Energy Savings.................................................................3-8 Table 3-6 Efficiency Project Peak Demand Savings..................................................................3-9 Table 3-7 Economic Acceptability of Efficiency Options ..........................................................3-10 Table 3-8 Benefit-to-Cost Ratio for the Best Option in each Category ....................................3-11 Table 3-9 Levelized Cost in /kWh for the Best Option in each Category ...............................3-12 Table 3-10 Acceptable Efficiency Projects Without Considering Savings From Option

Voltage Reduction............................................................................................................3-12 Table 3-11 Effect of Parameter Value Increase on Benefit-Cost Ratio and Levelized Cost ....3-13 Table 3-12 Benefit-Cost Ratio Resulting from Scaling Individual Parameter Values by 2

and 0.5 for Circuit D Option VF ........................................................................................3-14 Table 3-13 Levelized Cost Resulting From Scaling Individual Parameter Values by 2 and

0.5 for Circuit D Option VF ...............................................................................................3-15 Table 3-14 Optimal Options for Each Circuit Based on Economic Criteria ..............................3-18 Table 3-15 Efficiency Projects Tested .....................................................................................3-21 Table 3-16 Annual and Peak Savings for End-Use Load and Losses .....................................3-24 Table 3-17 Economic Analysis of Efficiency Projects ..............................................................3-26 Table 3-18 Efficiency Projects Tested .....................................................................................3-28 Table 3-19 Annual and Peak Savings for End-Use Load and Losses .....................................3-32 Table 3-20 Economic Analysis of Efficiency Projects ..............................................................3-34 Table 4-1 Case Study Feeder Summary ...................................................................................4-3 Table 4-2 Power-Factor Comparison of Circuit 1.......................................................................4-4 Table 4-3 Efficiency Analysis Comparison Summary ................................................................4-4

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Table 4-4 Power-Factor Comparison of Circuit 1 and Circuit 2 .................................................4-7 Table 4-5 Efficiency Analysis Comparison Summary ................................................................4-7 Table 4-6 Standard Efficiency Levels for Liquid-Immersed Distribution Transformers ............4-10 Table 4-7 Circuit Characteristics..............................................................................................4-15 Table 4-8 Comparison of Voltage Optimization Approaches ...................................................4-33 Table 4-9 Substation Transformer Characteristics ..................................................................4-34 Table 4-10 Substation Transformer Load Losses by Simulation Case....................................4-36 Table 4-11 Annual Energy Results for the Power Factor Sensitivity Case ..............................4-42 Table 5-1 Characteristic Circuit Statistics ..................................................................................5-3 Table 5-2 Transformer and Secondary Line Voltage Drop (120-V Base) Statistics...................5-4 Table 5-3 Secondary Annual Consumption and Losses..........................................................5-17 Table 5-4 Secondary Peak Demand and Losses ....................................................................5-17 Table 5-5 Loss Summary for Monitored Secondaries..............................................................5-29 Table 6-1 Hydro Quebec Comparison of CVR Factors by Load................................................6-4 Table 6-2 Comparison of Voltage Impact on End-Use Equipment ............................................6-5 Table 6-3 Regression Formulas for Each Normalization .........................................................6-10 Table 6-4 Circuit Characteristics..............................................................................................6-13 Table 6-5 Voltage Optimization Results From Field Trials.......................................................6-13 Table 6-6 Var Reduction From Voltage Optimization ..............................................................6-26 Table 6-7 Circuit A CVR Factors by Customer Type ...............................................................6-29 Table 6-8 CVR Var Factors for Circuits G and H .....................................................................6-46

Table A-1 Example Feeder Green Circuits Summary............................................................... A-2 Table A-2 Model Base Losses at the Peak-Hour and Annual Energy Losses.......................... A-7 Table A-3 Voltage Optimization Modeled Losses at the Peak-Hour and Annual Energy ......... A-9 Table A-4 Voltage Optimization Modeled Losses at the Peak-Hour and Annual Energy

Losses With Respect to the Base Case............................................................................ A-9 Table A-5 In-the-Field LTC Set-Point Variation Modeled Losses at the Peak-Hour and

Annual Energy Losses .................................................................................................... A-12 Table A-6 In-the-Field LTC Set-Point Variation Losses at the Peak-Hour and Annual

Energy Losses With Respect to the Base Case ............................................................. A-13 Table A-7 Voltage-Optimization Losses at the Peak-Hour and Annual Energy Losses

With Respect to the In-the-Field LTC Set-Point Variation Case ................................... A-14 Table A-8 Primary Voltage Across the Entire Feeder for Base Case, In-the-Field LTC

Set-Point Variation, and Voltage-Optimization Case....................................................... A-15 Table A-9 Phase Balance Case Modeled Losses at the Peak-Hour and Annual Energy

Losses............................................................................................................................. A-15 Table A-10 Phase-Balance Case Modeled Losses at the Peak-Hour and Annual Energy

Losses With Respect to the Base Case.......................................................................... A-16 Table A-11 Case 1 Re-Conductor Model Losses at the Peak-Hour and Annual Energy

Losses............................................................................................................................. A-17

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Table A-12 Case 1 Re-Conductor Losses at the Peak-Hour and Annual Energy Losses With Respect to the Base Case ...................................................................................... A-17

Table A-13 Case 2 Re-Conductor Model Losses at the Peak-Hour and Annual Energy Losses............................................................................................................................. A-18

Table A-14 Case 2 Re-Conductor Losses at the Peak-Hour and Annual Energy Losses With Respect to the Base Case ...................................................................................... A-18

Table A-15 Ideal Var Model Losses at the Peak-Hour and Annual Energy Losses................ A-19 Table A-16 Ideal Var Losses at the Peak-Hour and Annual Energy Losses With Respect

to the Base Case............................................................................................................. A-20 Table A-17 Capacitor Control Model Losses at the Peak-Hour and Annual Energy

Losses............................................................................................................................. A-20 Table A-18 Capacitor Control at the Peak-Hour and Annual Energy Losses With Respect

to the Base Case............................................................................................................. A-21 Table A-19 Efficiency Analysis Comparison Summary........................................................... A-22 Table A-20 Voltage Optimization Annual Losses With Respect to Base Cases..................... A-24 Table A-21 Varying LTC Annual Losses With Respect to Base Cases .................................. A-24 Table B-1 Distribution System Efficiency Factors ..................................................................... B-3 Table B-2 Financial Factors Used with Studies ...................................................................... B-24 Table B-3 Distribution Efficiency Study Summary .................................................................. B-25 Table B-4 Typical System Improvement Installed Costs ........................................................ B-26 Table B-5 Distribution Efficiency Savings ............................................................................... B-26 Table B-6 Distribution Efficiency Economic Evaluation .......................................................... B-27 Table B-7 End-Use VO Factors for Northwest H-1 and C-3 Climate Zones ........................... B-33 Table B-8 Heating and Cooling Zone Classifications.............................................................. B-34 Table B-9 System Investment Unit Costs ............................................................................... B-38 Table B-10 Recommended System Improvements ................................................................ B-39 Table B-11 Financial Factors Used in Study........................................................................... B-45 Table B-12 Economic Summary ............................................................................................. B-47 Table B-13 System Improvement Project Costs ..................................................................... B-48 Table B-14 Energy and Demand Efficiency Savings .............................................................. B-49 Table B-15 Economic Evaluation Detail.................................................................................. B-50 Table C-1 Efficiency Projects Tested........................................................................................ C-3 Table C-2 Annual and Peak Savings for End-Use Load and Losses ....................................... C-5 Table C-3 Economic Analysis of Efficiency Projects................................................................. C-7 Table C-4 Efficiency Projects Tested...................................................................................... C-10 Table C-5 Annual and Peak Savings for End-Use Load and Losses ..................................... C-11 Table C-6 Economic Analysis of Efficiency Projects............................................................... C-12 Table C-7 Efficiency Projects Tested...................................................................................... C-15 Table C-8 Annual and Peak Savings for End-Use Load and Losses ..................................... C-17 Table C-9 Economic Analysis of Efficiency Projects............................................................... C-19

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Table C-10 Efficiency Projects Tested.................................................................................... C-21 Table C-11 Annual and Peak Savings for End-Use Load and Losses ................................... C-24 Table C-12 Economic Analysis of Efficiency Projects............................................................. C-26

1-1

1 BACKGROUND AND FINDINGS

Electric power transmission and distribution systems typically have aggregate annual energy losses ranging from 7% to 10%. In aggregate, such percentage losses across all U.S. transmission and distribution equate to approximately 300 million MWh based on a U.S. annual generation total of 4,157 million MWh. That energy total is roughly equivalent to the energy needed to power approximately 29 to 35 million homes.1 Approximately two thirds of these losses are incurred at the distribution voltage levels.

Historically, power delivery loss reduction, especially distribution system losses, has often been a secondary priority because of uncertainties in quantifying loss improvements and the difficulty in obtaining sufficient return on investment for projects undertaken. Recently, however, an increased industry and regulatory focus on climate change and energy efficiency has led to a renewed evaluation of power distribution efficiency.

A clear understanding of the magnitude of T&D losses is the first step in improving system efficiency. Several recent advancements have made it possible to more readily identify options for reducing distribution loss and improving overall system efficiency, including:

Improved metering that provides data on end-use patterns and diversity factors.

Improved communication and control capabilities that allow more precise voltage and reactive power (var) control.

An overall improvement in modeling capabilities that allows for better loss estimation, targeting of solutions, and ways to test and identify improvements.

While specific utility and circuit characteristics often dictate achievable efficiency levels, the wide variation in distribution losses reported from one utility to another suggests that some utilities or some circuits particularly have significant opportunity for more efficient operation.

In addition to reducing losses, electric distribution companies can increase efficiency through management of end-use customer consumption. Utility voltage control can be used to reduce energy consumption and peak demand. There is still significant work needed to quantify the potential gains through voltage reduction across regions and load types. Existing work in this area may need updating because end-use loads are changing with less use of purely resistive loads and pure motor loads and more use of fluorescent lights, adjustable-speed drives, and electronics.

1 Electric Power Industry 2007: Year in Review, EIA report released Jan. 21, 2009

Background and Findings

1-2

Green Circuits Project and Objectives

The EPRI Green Circuits collaborative project was initiated following a series of industry workshops held from December 2007 through March 2008, in which more than 30 utilities explored issues related to distribution efficiency. The conclusions from the series of workshops formed the main objectives for the project, which include:

Develop and demonstrate a consistent method to quantify losses.

Compile credible data to quantify the costs, benefits, and risks of using energy efficiency and loss mitigation as a part of planning.

Demonstrate real-life examples where options for efficiency improvement have been implemented and validate realized efficiency gains.

These objectives formed the basis for an EPRI collaborative utility project titled Distribution Green Circuits, which officially began in April 2008. Since launch, 22 utilities have joined the collaborative effort. Most of the participating utilities have worked with EPRI staff to identify four or more specific distribution feeders for which detailed models have been or will be developed to characterize existing circuit losses and prioritize potential options for efficiency improvement. Since the completion of this analysis, each utility has evaluated actual field implementation of one or more efficiency options.

Distribution Efficiency

Although not a high priority, distribution efficiency has always been a consideration of distribution planners. Most reports on distribution planning include efficiency evaluations.2-4 Another good resource is the NRECA Power Loss Management report.5

Conservation voltage reduction was studied extensively in the 1980s, including work by EPRI.6,7 Voltage reduction has recently had a resurgence of interest as a way to use the distribution system for energy conservation. The Northwest Energy Efficiency Alliance (NEEA) and their contractor RW Beck and several utilities evaluated voltage reduction along with other efficiency options in the U.S. Pacific Northwest.8 In many ways, the Green Circuits project is an extension of the NEEA study to cover more circuits and more parts of the United States and even European

2 CEA, CEA Distribution Planner's Manual, Canadian Electrical Association, 1982. 3 IEEE Tutorial Course, Power Distribution Planning, 1992. Course text 92 EHO 361-6-PWR. 4 Willis, H. L., Power Distribution Planning Reference Book, Marcel Dekker, Inc., 1997. 5 NRECA Cooperative Research Network, Power Loss Management for the Restructured Utility Environment, 2ed.

2004. 6 D. Kirshner and P. Giorsetto, Statistical Tests of Energy Savings Due to Voltage Reduction, IEEE Transactions

on Power Apparatus and Systems, vol. PAS-103, no. 6, pp. 120510, June 1984. 7 Effects of Reduced Voltage on the Operation and Efficiency of Electric Loads, vol. 1, EPRI, Palo Alto, CA: 1981.

EPRI EL-2036. 8 NEEA 1207, Distribution Efficiency Initiative, Northwest Energy Efficiency Alliance, 2007. Available at

http://rwbeck.com/neea/.

Background and Findings

1-3

circuits. In 2010, the U.S. DOE PNNL laboratory release a report where they estimated that conservation voltage reduction could reduce energy consumption by 3% nationwide.9

Voltage optimization is a term used to optimally apply voltage reduction. The DOE Bonneville Power Administration (BPA) has implemented a distribution system energy efficiency program to help promote energy.10 Voltage optimization is a key component of the program. BPA specifies a simplified verification protocol to quantify program energy savings.11

Transformer efficiency is another area of recent interest. The Oak Ridge National Laboratory estimates that distribution transformers account for 26% of transmission and distribution losses and 41% of distribution and subtransmission losses.12 The DOE has instituted minimum efficiency requirements for distribution transformers.13 Amorphous-core transformers offer the potential for improved energy savings.14

In 2008, EPRI started a research program specifically to evaluate transmission and distribution efficiency: Research Program 172: Efficient Transmission and Distribution Systems for a Lower Carbon Future. As part of Program 172, the following reports were developed:

Distribution System Losses Evaluation, Reduction: Technical and Economic Assessment. EPRI, Palo Alto, CA: 2008. 1016097. http://my.epri.com/portal/server.pt?Abstract_id=000000000001016097

Main results: Framework for performing a distribution system loss study.

Impacts of Substation Transformer and Bus Configuration on Distribution Losses. EPRI, Palo Alto, CA: 2009. 1018584. http://my.epri.com/portal/server.pt?Abstract_id=000000000001018584

Main r