distribution measures: voltage reduction and optimization josh rushton cvr/vo subcommittee may 8,...

Distribution Measures: Voltage Reduction and Optimization

Josh RushtonCVR/VO Subcommittee

May 8, 2015

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

2

Especially this

http://rtf.nwcouncil.org/meetings/2015/01/

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

3

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)

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

http://rtf.nwcouncil.org/meetings/2012/11/Voltage%20Optimization%20Standard%20Protocol%20REV10%2011-09-12.docx

http://rtf.nwcouncil.org/subcommittees/cvr/Draft_CVR%20Protocol%20wEfficiency.docx





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

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

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

(Simplified) Voltage Optimization Protocol

10 – Simplified VO Protocol


– Capture savings on customer side of meter (models needed for distribution savings)




http://rtf.nwcouncil.org/meetings/2012/11/Voltage%20Optimization%20Standard%20Protocol%20REV10%2011-09-12.docx

• 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…


Eligibility

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


Steps to estimating savings

Big question #1: Are the performance thresholds needed for ∆V?

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.)


Simple ΔV Formula

• 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%


Performance Thresholds (1)

• 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


Performance Thresholds (2)

• 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?


Discussion

(Automated) CVR Standard Protocol #1

18 – CVR Protocol #1


– Capture savings on customer side of meter (models needed for distribution savings)









• 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…


Eligibility

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)



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



Does this ∆V need to be right, or just consistent with regression?

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)


Performance assessment

• 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?


Discussion

Additional Slides

25 – Additional slides

• 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


Additional Slide: CVR #1 Persistence

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)


distribution measures: voltage reduction and optimization josh rushton cvr/vo subcommittee may 8,...

Documents

cvr savings

savings calculations

overview slide

distribution savings

overview savings factor

canned savings factors

reliable savings estimates

deeper savings greater