Conservation Voltage Reduction and Voltage Optimization

Tyler Patton - SAIC

Overview •  System statistics and drivers for CVR / VO •  What is CVR? •  Why does CVR work? •  What is VO? •  Why implement VO? •  Case study

CVR  =  Conserva-on  Voltage  Reduc-on          VO  =  Voltage  Op-miza-on    

System Statistics •  198.8 MW peak •  640,620.5 MWh annual energy purchases

•  603,030.3 MWh annual energy sales

•  31,200 members

•  7 distribution substations

•  2,200 miles of distribution

•  Distribution is operated at 12.5/7.2 kV

MW = Megawatt MWh = Megawatt-hour kV = kilovolt  

Potential Drivers for a Utility •  New technologies can improve operation, monitoring, and

control •  New rates from power supplier •  Opportunity to receive grant funding from the power supplier •  Support robust SCADA implementation plan •  Stewards of our systems

–  Optimize to improve efficiency and leverage existing assets –  Postpone expensive system upgrades or investments –  Provide cost-effective solutions for utility and members

SCADA  =  Supervisory Control and Data Acquisition

What Is Conservation Voltage Reduction?

End  of  Feeder  

At Substation

Minimum Allowable Voltage on Primary Line

∆V = 1.5V

5 V  =  Volts  

Why Does Conservation Voltage Reduction Work? Load Types

6

Source: IEEE Std 399-1980 – Recommended Practice for Industrial & Commercial Power System Analysis (Brown Book)c

S Si

V Vi

= k( )( )

k = 0 Constant SPQ

k = 1 Constant I k = 2 Constant Z

PU  =  Per  Unit          S  =  Constant  Power          Si  =  Constant  Power          V  =  Volts          Vi  =  Voltage          SPQ=  Constant  Power  I  =  Constant  Current          Z  =  Constant  Impedance          IEEE  =  Ins-tute  of  Electrical  and  Electronics  Engineers    

What Is Voltage Optimization?

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1. Voltage optimization •  Combina-on  of  distribu-on  efficiency  and  conserva-on  voltage  reduc-on  

2. Why distribution efficiency? •  System  improvements  reduce  losses  and  flaJen  voltage  profile  •  More  distribu-on  systems  can  take  advantage  of  CVR  •  Ensures  a  certain  level  of  distribu-on  system  stability  •  Reduces  risk  of  supplying  low  voltage  to  customers  

CVR  =  Conserva-on  Voltage  Reduc-on  

126 Volts

120

114

121 126 125 124 122 123

Nor

mal

Vo

ltage

O

pera

tion

Average Voltage Standard Practice

Normal Voltage Operating Range in Current Practice by Utilities

What Is Voltage Optimization?

Feeder Length

Voltage At Min

Voltage At Peak

8

126 Volts

120

114

CVR

– L

ower

Vo

ltage

Average Voltage Standard Practice

Average Voltage CVR

ΔV

Feeder Length

Conservation Voltage Reduction – Lowering the Voltage

Apply Line Drop Compensation: •  Changes voltage profile and allows additional voltage reduction

121 126 125 124 122 123 120 124 123 123 121 122

9 CVR  =  Conserva-on  Voltage  Reduc-on          V  =  Volts  

126 Volts

120

114

Volta

ge

Opt

imiz

atio

n

Average Voltage Standard Practice

Average Voltage CVR

ΔV

Feeder Length

Voltage Optimization

Voltage Optimization: •  Flattens voltage profile and allows additional voltage reduction

120 124 123 123 121 122 115 120 119 118 116 117

Average Voltage VO Practice

•  Mitigates/prevents risk of low voltage and customer power quality issues.

ΔV Increased

!  

10 CVR  =  Conserva-on  Voltage  Reduc-on          V  =  Volts          VO  =  Voltage  Op-miza-on  

Case Study: Substation A •  (2) 161-12.47 kV, 25/33.3/41.6-46.7 MVA transformers •  (6) 12.5/7.2 kV distribution feeders •  300 miles of distribution •  4,600 members •  19.9 MW peak at 96% Pf (Summer) •  20.6 MW peak at 98% Pf (Winter) •  Regulated at 126 V

11 kV  =  kilovolts          MVA  =  Megavolt-­‐amperes          MW  =  MegawaJ          Pf  =  Power  Factor          V  =  Volts  

Case Study: Strategies •  Strategies evaluated

–  Load balancing –  Capacitor placement –  Reduce voltage with LTC and regulators –  Add monitoring points, as needed

•  Other strategies available –  Multi-phasing –  Feeder and substation load optimization –  Reconductor backbone

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Goal: Reduce losses

and flatten voltage profile

LTC  =  Load  Tap  Changer  

Case Study: Performance Thresholds

1. Phase balancing – loss savings > 1 kW

2. Feeder power factor > 99%

3. Voltage at meter > 114 V and < 126 V (ANSI® range)

4. Monitoring points for voltages > 115 V

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ANSI is a registered trademark of American National Standards Institute in the U.S. and/or other countries.

MW  =  MegawaJ          V  =  Volts          ANSI  =  American  Na-onal  Standards  Ins-tute          kW  =  kilowaJ  

Case Study: Voltage Reduction Event

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•  Percentage Voltage Reduction – 5.0% (T1); 3.5% (T2)

•  Percentage Demand Reduction – Unknown –  Used same time period for three days prior to the event to trend change in demand

•  Estimated % Demand Reduction – 4.47% (T1); 2.09% (T2)

•  CVR Factor = %  𝐷𝑒𝑚𝑎𝑛𝑑  𝑅𝑒𝑑𝑢𝑐𝑡𝑖𝑜𝑛/%  𝑉𝑜𝑙𝑡𝑎𝑔𝑒  𝑅𝑒𝑑𝑢𝑐𝑡𝑖𝑜𝑛 

–  0.89  (T1);  0.60  (T2) T1  =  Transformer  1          T2  =  Transformer  2          CVR  =  Conserva-on  Voltage  Reduc-on    

Case Study: Load Mix (Summer)

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•  Transformer 1 CVR Factor = 0.89 –  %Z = 8 –  %I = 82 –  %PQ = 10

•  Transformer 2 CVR Factor = 0.60 –  %Z = 7 –  %I = 53 –  %PQ = 40

CVR  =  Conserva-on  Voltage  Reduc-on          Z  =  Constant  Impedance          I  =  Constant  Current      

Case Study: Recommendations

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Jena Substation Change Phase of

Taps

Regulators Capacitors Add Monitoring Points Add Remove Add Remove

Transformer 1

Feeder 1 1 1

Feeder 2 3 1 1 1

Feeder 3 1 1 1 1

Transformer 2

Feeder 1 2 1 1

Feeder 2 1 2 1

Feeder 3 3 2 1

Case Study: Analysis Summary

17 MW  =  MegawaJ  

Case Study: Analysis Summary

10.0

20.0

30.0

4:00

4:20

4:40

5:00

5:20

5:40

6:00

6:20

6:40

7:00

7:20

7:40

8:00

8:20

8:40

9:00

9:20

9:40

10:00

Dem

and  (MW)Estimated Reduction with CVR/VO

CVR/VO

Substation  A

18 CVR  =  Conserva-on  Voltage  Reduc-on  VO  =  Voltage  Op-miza-on          MW  =  MegawaJ  

Case Study: Analysis Summary

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Notes: 1. Assumes CVR event at summer and winter peak at a demand rate of $8/kW 2. Assumes four-hour duration of CVR event for the summer and winter peaks and an energy rate of $0.05/kWh

Average Voltage

Reduction (ΔV)

Estimated Demand Savings (1)

Estimated Energy Savings (2)

Total Estimated Annual Savings

($) (kW) Annual ($) (kWh) Annual ($)

Summer Peak 3.5 V (2.78%) 3,505 $28,040 14,020 $701 $28,741

Winter Peak 3.8 V (3.10%) 3,868 $30,944 15,472 $773 $31,717

Annual Total - 7,373 $58,984 29,492 $1,475 $60,459

V  =  Volts          CVR  =  Conserva-on  Voltage  Reduc-on          kW  =  kilowaJ          kWh  =  kilowaJ-­‐hour  

Thank You

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Tyler Patton Associate Engineer, Transmission and Distribution Planning and Analysis 131 Saundersille Road, Suite 300 | Hendersonville, TN 37075 Tel: 615.431.3245 | Email: Tyler.M.Patton@saic.com Visit us at saic.com