Considering DER at Arizona Public Service

Stephen Kerr

September 19, 2016

Overview of Today’s Presentation

• APS System Overview

• DER Team and Pilots

• Data, data, and more data

• Future of Distribution Planning with DER

• Lessons Learned

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APS System

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• 1600 radial feeders

• 1.2 million customers

• 35 thousand square miles

• Demand: 60% residential, 40% C&I

• 29 thousand miles of distribution lines

• 6 thousand miles transmission lines

• 6.5 GW owned generation fleet

APS System Load

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0

1000

2000

3000

4000

5000

6000

7000

8000

0 50 100 150 200 250

Syst

em

Lo

ad (

MW

)

Time of Day (5-min intervals)

Summer Peak Day

Low Load Day

Min = ~2400 MW @ 3:30AM

Max = ~7400 MW @ 5:30PM

These two conditions occur only 2-3 months apart

APS System Load

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APS Renewable Integration

• Approximate installed capacity– Wind: 100 MW

– Utility scale solar: 400+ MW

– Rooftop solar: 350+ MW

• Growth rate:

– 2000 applications / month

– 14 MW / month

– 175 MW / year

• Renewables growth rates

– From 2013 to 2015

• Nameplate increased by 73 %

• Capacity at peak increased by 213 %*

*http://www.csp-alliance.org/solana-abengoa/

DER Pilot Programs at APS

• Sandvig High Penetration Solar Deployment in Flagstaff

– APS-owned solar and advanced metering

• Solar Innovation Study

– Install advanced tech on 75 homes

• Solar, battery, load controller, pool pump, Smart HVAC

– Study usage patterns

• Solar Partners Program

– Install utility-operated

solar on 1500 homes

– Customers get $30/mo credit

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Challenge: Managing 350MW Generation

Creating the DER team

• New department formed spring 2016

• 4 Engineers and an Engineering Leader

• Studying system aggregate impact of DERs

• Long term vision is to roll up to the bulk electric system

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Where is the data?

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DER Integration Engineering

DER Integration Engineering

GISCIS

CYME

DA

EMS PiTLM

AMI

Maximo

Interconnects

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Data Sources

• APS bills on net metering, but has two AMI meters per customer with DER

– Billing meter

– Production meter

• Allows APS to study disaggregated data

– Pull out production

– Determine gross load Credit: EPRI/APS Solar Partner Program: June 2016 Update

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Source: kathleendeery.com

Challenges Using Data

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Data Sources

• Assessment

– All the right data is available

– Under-utilized

– Coordinated processes required

• Challenges

– Pertinent data not linked

– Difficult to make actionable decisions

– Quality and accuracy verification

Distribution Planning: Current state

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DER Operating Challenges

• Thermal issues– Masked load skews historical data

• Voltage– Rise with low daytime load– Drop with heavy load/no solar

• Feeder switching– ‘True’ load on line sections– Installed capacity insufficient– Interaction (solar + load) is critical– Auto-transfer schemes

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DER Operating Challenges

• Protection Coordination

– Relay desensitization

– Reverse flows, unbalance, mis-coordination

• Advanced Grid systems

– Self-healing

– IVVC

– SCADA-controlled line switches

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Distribution Planning Challenges

• Thermal issues– Probabilistic assessment of coincident load/solar

at feeder level

• Voltage rise/drop– Forecasting/simulating voltage problem areas

• Feeder switching– Operational planning

• Model validation– Verifying GIS model parameters

– Running power flow / protection coordination studies

Distribution Planning: Future state

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Transition to Integrated DER planning

• Data aggregation– Assimilate data to see system layer impacts

• Data visualization– Automate routine studies– Easily view and act upon information

• Modeling and simulation– Simulate existing conditions, and mitigation– Enhance Distribution and Transmission planning processes– Disaggregate true load from solar

• Verification from operations– Engage operators and field personnel

Hub

Data

Data

Data

DER Integration Challenges

• How do you forecast DER growth?

• What conditions drive immediate system upgrades?

– Voltage exceptions

– Impact to duration of outages (SAIDI)

• What conditions drive scheduled system upgrades?

– Gross demand causes feeder overload

• What % and how long? Still TBD

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DER Integration Challenges

• How do different DER sources impact utility-scale decisions?– Energy Efficiency

– EV’s

– PV/solar

– Batteries

• Screening process for interconnections– Based on FERC SGIP?

– Deny applications on problem feeders?

– Short and long term hosting capacity studies

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Current studies under way

• Identify net and gross demand per feeder• Reminder – this is in reference not only to installed

capacity, but actual production values

• Study load duration curves

• Voltage profile visualization

• ID candidate feeders for additional DER

• Collaborate with all internal departments involved with some form of DER

• New modeling and visualization software22

Lessons Learned

• Scattered data sources complicate feeder studies

• Validate models and real-world conditions with AMI data

• PV orientation matters– For SPP feeders, peak reduction 22% (avg) vs 62% (west-

only)– For more typical feeder, 10-30% of installed capacity at

peak

• Predominant DER is PV and does not yet have much value in deferring projects

• Voltage is a major concern23

Questions?

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Stephen Kerr, PEArizona Public ServiceStephen.Kerr@aps.com