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