Conservation Voltage Reduction (CVR)
Voltage Optimization (VO)
Josh Rushton
Regional Technical Forum
July 21, 2015
2
Objective
Today, we’re seeking RTF decisions on two
standard protocols:
• Automated CVR: Recommend deactivation.
– Intent is only to move to Custom Protocols
– Protocol’s method is still a reasonable approach
– Still a lot of CVR savings out there
• Simplified VO: Recommend approval.
– Proven category, active status.
– Proposal includes major protocol changes
3
Outline
• Background
• Simplified VO
– The big shift
– Reliability
– Decision
• Automated CVR
4
Background
5 -- Background
What are these measures about?
Basic idea:
126
Some things use
less energy at
lower voltages
124
Voltage
122
120
118
Complication 1:
116
Average ΔV can be
hard to estimate
114
Complication 2:
ΔV
112
0
2
4
8
Miles from substation
Savings factors (%ΔKWh per %ΔV) depend on
end-use mix.
•
•
6
(PNNL, 2010) gives some lab results;
(NEEA, 2008) reflects residential mix circa 2006.
Artist’s rendering
(fake data)
6 -- Background
Two Standard Protocols
Automated CVR Protocol #1: Collect 90 days of alternating dayon/day-off data, use to estimate feeder-specific savings factors
•
•
Early version approved by RTF in 2004
Major revision November, 2011 (latest draft dated May 15, 2012)
– Stalled out in subcommittee
– Main sticking point was proposed eligibility requirements
%ΔkWh
%ΔV
Simplified VO Protocol: “Canned” savings factors derived from
NEEA’s DEI research (NEEA, 2008)
•
•
Early version approved by RTF May, 2010, good background info in April, 2010
Revised version brought to RTF in November, 2012
– RTF sent back to subcommittee for further discussion
– Subcommittee took a step back to consider a change of course
Both protocols stalled out at end of 2012
•
Both currently Under Review.
7 - Background
Recent RTF Direction
• RTF (January, 2015): Find out what it would take to “dress
up” the protocols
– Clarify terms like mostly residential, review treatment of
persistence, …
– Check whether eligibility can be expanded
• Subcommittee: CAT should compare requirements to DEI study/data
• Result: No clear answers without major effort; probably none with
major effort
• RTF (January, 2015): Are RTF standard protocols really a
good fit for these measures?
– RTF Standard Protocols seem too narrow
– Maybe some kind of “custom guidance” would be better
– Subcommittee (May, 2015): Very limited discussion of this issue
8
Simplified VO
Protocol
9 – Simplified VO
Measure Overview
• Measure Name:
Voltage Optimization
• Method:
Standard Protocol
• Category:
Proven
• Current Status:
Under review
• Proposed Status:
Active
• Proposed Sunset Date:
July, 2020
• Highlighted areas:
Eligibility, reliability
10 – Simplified VO
Two Standard Protocols
Automated CVR Protocol #1: Collect 90 days of alternating dayon/day-off data, use to estimate feeder-specific savings factors
•
•
Early version approved by RTF in 2004
Major revision November, 2011 (latest draft dated May 15, 2012)
– Stalled out in subcommittee
– Main sticking point was proposed eligibility requirements
Simplified VO Protocol: “Canned” VO savings factors derived from
NEEA’s DEI research (NEEA, 2008)
•
•
Early version approved by RTF May, 2010, good background info in April, 2010
Revised version brought to RTF in November, 2012
– RTF sent back to subcommittee for further discussion
– Subcommittee took a step back to consider a change of course
Both protocols stalled out at end of 2012
•
•
•
Both currently Under Review.
Recommend deactivating Automated CVR Protocol #1
Recommend approving modified version of Simplified VO Protocol
11 – Simplified VO
The “canned” VO factors
• VO factors quantify %ΔkWh per %ΔV
• Values in VO factor table based on NEEA Load
Research Project
– Vary by climate, saturation of AC and ER heat
– Only counts end-user energy savings (distribution
losses calculated separately)
– Reflect residential end-use mix
• Tables need periodic review/update to reflect
changes in end-use stocks
• May be possible to expand tables to include
values for VO factor more commercial loads
12 – Simplified VO
Motivation
Why build an RTF protocol around the VO factor
tables?
• VO factor tables have potential to simplify
savings estimates for a lot of feeders
• An RTF protocol has several functions
– Describing how to get reliable estimates from
simplified methods
– Maintaining reliability via sunset check-ins
– Making conservation credits more predictable
13 – Simplified VO
The tricky part
VO factor (%ΔkWh / %ΔV) only useful if you can
estimate ΔV
• Why? Savings estimated as ΔkWh = kWhAnnual * VOf * %ΔV
• What? ΔV target is average annual change in voltage
experienced by end users
• How? That’s the tricky part.
– Easy to estimate ΔV for very linear systems
• Performance thresholds increase linearity but restrict eligibility
• See Additional Slides for details
– Voltage usually not very linear in the wild
– Are reliable ΔV estimates ever possible without meeting all
thresholds? (Answer: Probably sometimes)
14 – Simplified VO
Proposed approach
• Describe the circumstances and
method where we know savings is
reliable
• Point out some things you need to be
careful about when you deviate from
that method or those circumstances
• This is a new approach to RTF
Standard Protocols.
15 – Simplified VO
How the proposed protocol works
• Proposed Protocol describes Benchmark Method, same as
sole Savings Method in previous protocol drafts.
– Savings method (with formulas that assume linearity)
– Performance thresholds (which support linearity and measure persistence)
– Data collection (what’s needed for savings method inputs and reliability
checks)
– Details in Additional Slides
• Proposal allows other approaches (besides Benchmark
Method) but does not specify alternatives
– Totally different, unforeseen, approaches
– Minor tweaks (may alter savings method, performance thresholds, data
collection, or any combination)
16 – Simplified VO
Proposed Reliability Framework
• Basic Eligibility Requirement: “The practitioner can reliably estimate the
average annual change in voltage that is experienced by end-users as a
result of the measure”
• Reliability Standard: “…reliability similar to the Benchmark Method”
• Validity Threats: “At a minimum, protocol documentation must
demonstrate that the final calculations address” threats related to four
issues: Extrapolation, Annualization, Baseline, Persistence
– Protocol notes how performance thresholds address threats in Benchmark
Method
– Protocol does not specify what it means to address the threats in general
• Language similar to above used in both Eligibility and Delivery Verification
sections
• Intent: Describe circumstances where RTF “certifies” reliability. Leave
grey areas of reliability to regulators, evaluators, and utilities, but with
“some lines drawn on the playing field”
17 – Simplified VO
Validity Threat: Extrapolation
“Is the ΔV estimate based on a reliable approach to
extrapolating data collected at the selected metering locations
(e.g., source and EOL) to customers along the feeder?
“In the benchmark method, this extrapolation is based on a
linear model of voltage decay along the length of each feeder,
and the performance thresholds support this linear
assumption.”
18 – Simplified VO
Other Validity Threats
•
•
•
•
Annualization
Baseline
Persistence
See Additional Slides
19 – Simplified VO
Minor Changes
• Clear statement of “right-on-average” reliability standard
• “Mostly residential” requirement given specific definition (at
least 80% of feeder load due to residential end-users, the rest
light commercial)
• Moved four-step integrated planning process to Appendix
• Removed delivery verification items that only related to the
planning process (rather than reliability of savings)
• Editorial stuff
20 – Simplified VO
Staff/CAT Recommendation
Recommend approving Simplified VO
Protocol with proposed modifications
• Status: Active
• Category: Proven
• Sunset date: July 31, 2020
21 – Simplified VO
Proposed Motions
“I, _________, move that the RTF approves the
Standard Protocol for Voltage Optimization as
presented (active status, proven category,
sunset date of July 31, 2020)”
22
Automated
CVR Protocol
#1
23 – Automated CVR
Two Standard Protocols
Automated CVR Protocol #1: Collect 90 days of alternating dayon/day-off data, use to estimate feeder-specific savings factors
•
•
Early version approved by RTF in 2004
Major revision November, 2011 (latest draft dated May 15, 2012)
– Stalled out in subcommittee
– Main sticking point was proposed eligibility requirements
Simplified VO Protocol: “Canned” savings factors derived from NEEA’s
DEI research (NEEA, 2008)
•
•
Early version approved by RTF May 4, 2010
Revised version brought to RTF in November, 2012
– RTF sent back to subcommittee for further discussion
– Subcommittee took a step back to consider a change of course
Both protocols stalled out at end of 2012
•
•
•
Both currently Under Review.
Recommend deactivating Automated CVR Protocol #1
Recommend approving modified version of Simplified VO Protocol
24 – Automated CVR
Savings method summary
• Data collection: Minimum of 90 days, raise and
lower control-zone voltage to get day-on/day-off
CVR operation cycles.
• Savings factors: Primary data used to estimate
feeder-specific savings factor (%ΔKWh/%ΔV) for
each application
– Factors capture savings on both sides of meter
– Protocol directly measures switchable savings (models
used capture other savings components)
• Energy savings: Savings estimated as product of
savings factor, annualized average ΔV, annual
kWh (based on historical data).
25 – Automated CVR
Reasons to deactivate
• Method (day-on/day-off) is a version of best-practice
– Has traction (people reference it, use as benchmark)
– Little or no simplification over custom alternatives
– Primary value is consistency of estimation method
• Practitioners want more flexibility
–
–
–
–
Performance thresholds are controversial
Minor tweaks (e.g., how to normalize for weather or weekends)
Very different methods (e.g., all-year-on study, w/ comparison feeders)
Existence of proven RTF Protocol not supposed to obstruct alternative
methods (but some say it does)
• Staff/CAT/Subcommittee resources needed to land the protocol
–
–
–
–
Find a path through (or around) performance thresholds
Incorporate model improvements / tweaks
Would push back other measures (for what pay-off?)
Might fail to land anyway
26 – Automated CVR
Effect of deactivation
• Eligible projects will have to go Custom (most
already end up there)
• Day-on/day-off method will have no home
within a proven RTF document
– Doesn’t mean method isn’t reliable
– Document will remain on RTF website
– Practitioners/regulators may still agree to use the
approach when helpful
• Reserve RTF Staff/CAT/Subcommittee
resources for other tasks
27
Proposed Motion
“I, _________, move that the RTF deactivates
the Automated CVR Standard Protocol #1
because the protocol’s value to stakeholders is
not sufficient to justify the RTF resources
needed to prove out the protocol.
– This decision does not imply that the protocol’s
method is unreliable;
– This decision does not imply diminished savings
potential for eligible measures.”
28
Additional
Slides
29 – Additional Slides
Simplified VO: Baseline Notes
From the proposed protocol:
“Baseline. A term from the RTF Guidelines. The Baseline is the inefficient-case performance level
referenced in savings calculations. Voltage optimization uses a pre-conditions baseline, which
means that savings estimates should try to capture the difference in energy consumption
between the pre-existing system and the efficient-case system, except when the pre-existing
system includes obsolete equipment (in which case, the Baseline is the hypothetical system that
would result if essential improvements were made to the pre-existing system).
•
“Some measure applications include or coincide with physical system improvements that are
designed to drive deeper savings or improve system reliability. These measures can also lead
to more predictable system performance, which may improve reliability of the average
annual voltage estimates. In such cases, it may be possible to improve savings reliability by
estimating Baseline performance using meter data collected after physical improvements are
completed, but using operational settings that emulate average voltage conditions of the PreExisting System. The Benchmark Method takes this approach.”
•
“This protocol does not specify what constitutes obsolete equipment in a distribution system.
A generic test is that equipment is obsolete if near-term improvements would be inevitable,
even if the energy-efficiency measure was not being implemented.”
30 – Simplified VO
Simplified VO: Validity Threats (1)
Annualization
“Is the ΔV estimate based on a reliable approach to annualizing
data collected during the metering period?
“In the benchmark method, the meter-period voltage estimates
are scaled up or down in proportion to the ratio (average annual
demand)/(average meter-period demand). This kind of scaling
assumes that voltage normally rises and falls roughly in
proportion to demand; this assumption is supported by the
performance thresholds.”
31 – Simplified VO
Simplified VO: Validity Threats (2)
Baseline
“Does the ΔV estimate reflect the correct baseline? See
[Baseline Notes, above].
“If the VCZ includes obsolete equipment prior to the Voltage
Optimization measure, then the correct baseline is not the same
as the base-case system. Instead, it is the system that would
result if the obsolete equipment were replaced with components
that would be typical choices in the current market.”
32 – Simplified VO
Simplified VO: Validity Threats (3)
Persistence
“Can reasonable assurance be provided that the efficient-case
voltage settings will persist? In all applications of this protocol,
delivery verification requires that a 3-year persistence plan must
be documented to ensure that efficient system operation habits
become well-established. However, a persistence plan will not
be followed if customers experience adverse low-voltage events
during some portions of the year.”
“In the benchmark method, the performance thresholds ensure
predictable and reliable system performance throughout the
year so that efficient-case operations can be designed to reliably
avoid low-voltage events.”
33 – Additional Slides
Simplified VO: Benchmark Method
Performance Thresholds (1)
• Power factor (3-phase total, at source):
– Minimum (hourly) greater than 0.96
– Average (for week) greater than 0.98
• Phase load balance (3-phase lines, at source)
– Per-unit unbalance < 0.15
– Neutral < 40 amps
• Max-adjusted voltage drop (3-phase mean)
– Max-adjusted drop is mean meter-period drop, times
(annual peak kW) / (mean meter-period kW)
– Primary max-adjusted drop < 3.3%
– Secondary max-adjusted drop < 4.0%
34 – Additional Slides
Simplified VO: Benchmark Method
Performance Thresholds (2)
• Variation between feeder max voltage drops
– Compare feeders within substation control zone
– Must not differ by more than 2 Volts (on 120 V base)
• Primary line minimum hourly voltage
– Measured near expected low voltage point
– At least 114 V + (1/2) Voltage regulation bandwidth + secondary
max allowed voltage drop
• Primary line maximum hourly voltage
– Measured near expected high voltage point
– Less than 126 V - (1/2) Voltage regulation bandwidth
• Conductor loading
– Source hourly loading (amps) less than design normal spec
35 – Additional Slides
Simplified VO: Benchmark Method
Savings Method
Step 1. (Identify Savings Factor)
Look up VOf (%ΔkWh / %ΔV) in table
• Values vary by climate, saturation of AC and ER heat
• Remember: VOf only counts end-user energy savings
(distribution losses calculated separately)
Step 2. (Estimate ΔV)
See next slide.
Step 3. (Estimate Energy Savings)
ΔkWh (savings) = kWhANNUAL * VOf * %ΔV
• kWhANNUAL based on historical data
• ΔV is estimated average voltage difference between CVR-on
and CVR-off cases
36 – Additional Slides
Simplified VO: Benchmark Method
Formula for Estimating ΔV
For fixed voltage reduction, VO Protocol estimates average
voltage as follows, pre and post, and takes the difference:
1
𝐷𝑎𝑛𝑛𝑢𝑎𝑙
𝑉 = 𝑉𝑆𝑒𝑡 − ∗ 𝐴𝑣𝑒 𝑉𝑂𝑢𝑡,𝑖 − 𝑉𝐸𝑂𝐿,𝑖 ∗
2
𝐷𝑚𝑒𝑡𝑒𝑟
𝑉𝑆𝑒𝑡
= Regulator set point voltage setting
𝑉𝑂𝑢𝑡, 𝑖 = Hour-i metered regulator output voltage on 120 V base
𝑉𝐸𝑂𝐿, 𝑖 = Hour-i metered EOL primary voltage on 120 V base
𝐷𝑎𝑛𝑛𝑢𝑎𝑙 = Average annual kW demand (from measured historical data)
𝐷𝑚𝑒𝑡𝑒𝑟 = Average kW demand, metered at source
(Formula for line drop compensation and automated voltage
feedback control adds correction for volt rise.)
37 – Additional Slides
Some Recent DE Activity
• NEEA DEI Project Final Report (NEEA, 2008)
– Load Research Project (2005-2007)
– Pilot Demonstration Project (c. 2005-2007)
•
•
•
•
•
•
•
•
•
•
Distribution Efficiency Guidebook (NEEA, 2008)
Long-Term Monitoring and Tracking DE (NEEA, 2014)
Energy Smart Utility Efficiency (ESUE) Program (BPA, ongoing)
PacifiCorp DE Pilot Study
IEEE P1885. Guide for Assessing, Measuring and Verifying Volt-Var control
Optimization on Distribution Systems (Draft - Approval expected 2017)
Puget Sound Energy currently implementing VO
Avista CVR Program Impact Evaluation (Avista, 2014)
Evaluation of CVR on a National Level (PNNL, 2010)
M&V research by PNNL and WSU researchers (2014)
Green Circuits DE Case Studies (EPRI, 2011)