distribution measures: voltage reduction and optimization josh rushton cvr/vo subcommittee may 8,...
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Distribution Measures: Voltage Reduction and Optimization
Josh RushtonCVR/VO Subcommittee
May 8, 2015
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Today’s objectiveRTF request (from January): Estimate lift needed to resolve major concerns with existing protocols:• Balance flexibility, reliability, ease-of-use
– Performance thresholds– General approach
• Miscellaneous– Clarify terms (e.g., “mostly residential”)– Measure life issues – Narrow technical questions
Lift-size estimate should reflect particular goal(s)
Today’s objective: Recommendation on how major concerns should be addressed in CVR/VO protocols
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Especially this
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Outline• Overview– Background – The big issues– Reminder on scope and objectives
• (Simplified) Voltage Optimization Protocol– How it works – Performance thresholds– Discussion
• (Automated) CVR Standard Protocol #1 – How it works – Performance thresholds– Discussion
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Overview
4 – Overview
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Volta
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Miles from substation
Where do CVR savings come from?Basic idea:Some things use less energy at lower voltages
Complication 1:Average ΔV can be hard to estimate
Complication 2:
5 – Overview
Savings factor (%ΔKWh per %ΔV) depends on mix of end uses. See (PNNL, 2010) for some lab results
ΔV
Artist’s rendering (fake data)
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Two standard protocols…(Simplified) VO Protocol (Latest draft (under review) November, 2012)“Canned” savings factors (%ΔKWh/%ΔV) derived from NEEA’s DEI research • Factors vary by climate, AC saturation, and ER heat saturation• Factors based on data collected at residential end-user meters
– Capture savings on customer side of meter (separate calculations needed for distribution savings)
– Apply to mostly-residential feeders
(Automated) CVR Protocol #1 (Latest draft (under review) May 15, 2012)Uses alternating CVR-on/CVR-off data to estimate savings factor (%ΔKWh/%ΔV)• Directly measures switchable savings (models bring in other components)• Factors based on feeder-level data (captures savings on both sides of meter)
6 – Overview
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Big issue 1: Performance thresholds
Performance thresholds enable deeper savings (greater ΔV) in many cases– Good reason for recommendation but not for
requirement – Shouldn’t include in our test
Question for today: When are performance thresholds needed…– For reliable savings estimates? – For defining obsolete equipment?
7 – Overview
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Big issue 2: General approachBPA suggests some form of “custom guidance” • Advantage over using existing protocols: flexibility • Advantages over deactivating existing protocols:
– Could preserve simplified option, give VO tables a home– RTF can draw some boundaries for M&V
• Disadvantages (other than having to come up with “custom guidance”): – Savings calculations could be complicated, diverse
• Would need careful documentation and expert review • BPA custom project process includes review by ESUE engineer
• What kind of RTF document would this be?– RTF does not approve “methods” for custom protocols (Roadmap, p.7)– An uncommonly flexible Standard Protocol might fit with Guidelines
• Wouldn’t attempt to spell out all calculations• Would probably rely on practitioner credentials (how to specify?)
– Don’t have a detailed proposal for this.
Question for today: Can something like this achieve reliable savings estimates?
8 – Overview
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Reminder: Scope and ObjectivesProtocol savings estimates should be “right on average”• RTF exists to support use of EE as a resource. Protocols reflect
trade-offs between reliability and research expense that are appropriate for that role.
• May have insufficient rigor for other purposes (such as capital improvement decisions)
Bundling, when a group of related measures is cost-effective even though some individual components are not• RTF tries to avoid policies that require or ban bundling.
9 – Overview
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(Simplified) Voltage Optimization Protocol
10 – Simplified VO Protocol
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Two standard protocols…(Simplified) VO Protocol (Latest draft (under review) November, 2012)“Canned” savings factors (%ΔKWh/%ΔV) derived from NEEA’s DEI research • Factors vary by climate, AC saturation, and ER heat saturation• Factors based on data collected at residential end-user meters
– Capture savings on customer side of meter (models needed for distribution savings)
– Apply to mostly-residential feeders
(Automated) CVR Protocol #1 (Latest draft (under review) May 15, 2012)Uses alternating CVR-on/CVR-off data to estimate savings factor (%ΔKWh/%ΔV)• Directly measures switchable savings (models bring in other components)• Factors based on feeder-level data (captures savings on both sides of meter)
11 – Simplified VO Protocol
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• Primary electrical systems serving mostly residential and light commercial loads
• For each affected feeder, must be able to record hourly averages for a week pre- and a week post: – voltage (source and EOL, by phase), – ambient temperature (source), – KW and Kvar (source)
• Minimum performance thresholds– Based on 7-days of hour-level data for reflecting normal
operation pre and post-VO…
12 – Simplified VO Protocol
Eligibility
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Step 1. (Identify Savings Factor)Look up VOf (%ΔkWh / %ΔV) in table• Table based on NEEA Load Research Project• Values vary by climate, saturation of AC and ER heat • VOf only counts end-user energy savings (distribution
losses calculated separately)
Step 2. (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
13 – Simplified VO Protocol
Steps to estimating savings
Big question #1: Are the performance thresholds needed for ∆V?
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For fixed voltage reduction, VO Protocol estimates average voltage as follows, pre and post, and takes the difference:
= Regulator set point voltage setting= Hour-i metered regulator output voltage on 120 V base = Hour-i metered EOL primary voltage on 120 V base= Average annual kW demand (from measured historical data)= Average kW demand, metered at source
(Formula for line drop compensation and automated voltage feedback control adds correction for volt rise.)
14 – Simplified VO Protocol
Simple ΔV Formula
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• 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%
15 – Simplified VO Protocol
Performance Thresholds (1)
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• 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
16 – Simplified VO Protocol
Performance Thresholds (2)
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• Are the thresholds needed to get “reliable” average ΔV from the Simple Formula?
• Is a system obsolete (inevitable near-term improvements) if thresholds aren’t met?
• Conclusions/recommendations related to general approach?
17 – Simplified VO Protocol
Discussion
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(Automated) CVR Standard Protocol #1
18 – CVR Protocol #1
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Two standard protocols…(Simplified) VO Protocol (Latest draft (under review) November, 2012)“Canned” savings factors (%ΔKWh/%ΔV) derived from NEEA’s DEI research • Factors vary by climate, AC saturation, and ER heat saturation• Factors based on data collected at residential end-user meters
– Capture savings on customer side of meter (models needed for distribution savings)
– Apply to mostly-residential feeders
(Automated) CVR Protocol #1 (Latest draft (under review) May 15, 2012)Uses alternating CVR-on/CVR-off data to estimate savings factor (%ΔKWh/%ΔV)• Directly measures switchable savings (models bring in other components)• Factors based on feeder-level data (captures savings on both sides of meter)
19 – CVR Protocol #1
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• System type. Primary electric distribution systems serving any combination of res., comm., and industrial loads, operated radially, primary voltage ≥ 12.47 kV
• CVR control. CVR system can be switched on and off on a daily basis (voltage set points can be changed daily)
• System model. Protocol relies on load flow simulation model.
• Data collection. For each affected feeder, must be able to record hourly average… – voltage (source and EOL, by phase), – ambient temperature (source), – KW and Kvar (source)
• Performance thresholds…
20 – CVR Protocol #1
Eligibility
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Step 1. (Data collection)• Metering at feeder source: – Hourly average kW, kvar, voltage (each phase),
temperature
• Metering at “EOL” locations: – Select low-voltage points based on load flow simulation– Collect voltage (hour-level averages for each phase and
low-voltage point)
• Select 90 days for on/off CVR operation with data collection – Spread over the year, 30-day groups (get range of
conditions)
21 – CVR Protocol #1
Steps to estimating savings
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Step 2. (Regression)Estimate CVRf (%ΔkWh / %ΔV) via regression model fit with hour-level data.• Dependent variable is: kWh• Explanatory variables are: CDD, HDD, “zone-average” V • CVRf estimate is the coefficient of voltage variable.
Step 3. (Estimate Energy Savings)ΔkWh (savings) = kWhANNUAL * CVRf * %ΔV• kWhANNUAL based on historical data• ΔV is difference between estimated control-zone-average
voltage levels in CVR-on and CVR-off cases
22 – CVR Protocol #1
Steps to estimating savings
Does this ∆V need to be right, or just consistent with regression?
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Prior to CVR installation, do separately for each voltage control zone:
1. Collect historical data – Load shape, total energy, kvar data, customer mix, ER heat and AC kWh
estimates
2. Run load flow simulation model for Pre- and Post-CVR cases – Base on physical configuration, historical data, and proposed upgrades.
3. Use simulation model to test whether Pre- and Post-CVR systems meet performance thresholds: – Max. phase load imbalance < 20% (check peak/min kW)– Min. hourly power factor > 95% (check peak/min kW, peak/min kVA)– Voltage complies with ANSI C84.1 (check at EOL for peak/min kW)
23 – CVR Protocol #1
Performance assessment
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• Are the thresholds needed to get “reliable” average ΔV from the Simple Formula?
• Is a system obsolete (inevitable near-term improvements) if thresholds aren’t met?
• Conclusions/recommendations related to general approach? What about other statistical approaches?
24 – Simplified VO Protocol
Discussion
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Additional Slides
25 – Additional slides
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• Measure is operational, so persistence is tricky• Protocol specifies “post-period re-verification trigger”• Annual persistence review for three years after installation. • Check for changes in standard operation
– Source voltage (min, max, average), – Weather-adjusted annual energy– Average primary voltage– kW, kvar demand
• Any change ≥ 15% triggers full protocol do-over• Is this how we want to treat persistence?• Relevant to Simplified VO too, but not as much work to
redo there
26 – Additional slides
Additional Slide: CVR #1 Persistence
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References• 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’s DE Pilot Study• 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)
27 – Additional slides