PNM Prosperity Energy Storage
Implementing PV Smoothing and Shifting Simultaneously
August 2013 Update
…….
Public Service Co. of New Mexico
PNM’s Approach to PV and Smart Grid Technologies
Challenge/Opportunity: Solar energy is an intermittent resource with output changing in seconds rather than minutes
Data from Project Site - April 2012
Clear Day Cloudy
Day
Challenge/Opportunity: Solar peak does not align with actual system peak
The best solar production
occurs ~ 2 to 8 hours prior
to:
when the most power is
needed on the system
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500.0
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2500.0
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M
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M
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M
10
:00
AM
11
:00
AM
12
:00
PM
1:0
0 P
M
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M
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M
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Pe
ak A
vera
ge L
oad
(M
W)
PNM 2007-2011 System Peak Average Hourly Load by Month
SUMMER PROFILE
WINTER PROFILE
SOLAR PROFILE
PNM Prosperity Energy Storage Project - Description
Project Description
• Designed to both smooth PV intermittency and shift PV energy for on-peak delivery
• First of 16 DOE Smart Grid Storage Demonstration Projects to go on line – Sept 2011
• Successfully demonstrating true Storage/PV integration to Utility operations
Equipment
• 500 kW PV (fixed C-Si panels) – not DOE funded
• Ecoult/East Penn - Advanced Lead Acid Battery system for “shifting” – 1MWh
• Ecoult/East Penn - “Ultra” Battery system for “smoothing - 500kW
Cyber Secure, High Resolution Data Acquisition and Control System – 1 second and 30 samples per second data capture
Prosperity Project Goals
• Created a dispatchable, renewables-based peaking resource
• Combined PV and storage at a substation targeting 15% peak-load reduction
• Demonstrating a combination that can simultaneously mitigate voltage-level fluctuations as well as enable load shifting
• Developed power system models (baseline and projected), and cost/benefit economic models
• Generating, collecting, analyzing and sharing resultant data – Strong public outreach
• Enabling distributed solutions that reduce GHG emissions through the expanded use of renewables
Develop an even more beneficial Renewable Resource Transferable Nationwide
Results of Smoothing Tests
Solar Power Meter (kW)
Battery Meter (kW)
Solar Power Meter (kW)
Battery Meter (kW)
Solar Power Meter (kW) Site Power
Output (kW)
Smoothing Test Plan Results
• Variety of control inputs – PV Meter, Irradiance Sensors (average, individual)
• Variety of gains on input – tests different capacities of battery use
• Question is: how much smoothing is enough? Requires optimization analysis
Blue – PV
Yellow – Battery
Red – Primary Meter
Magnified
Clear Day Cloudy Day - Altocumulus
4/17-4/19/12 2 Clear Days & 1 Cloudy Day
4/19/12 Cloudy Day
4/19/12 4 Hour Window
4/19/12 15 Minute Window
Key: Blue=PV Output
Yellow = Battery Output
Red=System Output
PV Smoothing Demonstration
PV Smoothing Optimization – How much smoothing is enough?
EPRI Report on High Penetration on a Distribution System 1021982
Circuit Voltage on Studio Feeder 14
Prosperity Energy Storage Facility (No Smoothing)
Circuit Voltage on Studio Feeder 14
Prosperity Energy Storage Facility ( Smoothing)
Reliability Analysis
Visibility to LTC or Capacitor Operations due
to Voltage variation.
Smoothing control algorithm can target
LTC operations.
Economic Analysis (Battery life)
18% increase in the total kWh for the LPF
compared with the MA
Firming Preliminary Results – Market based dispatch
Blue = PV
Red= Site Output
Yellow = Battery
Early morning-
producing power
before the sun is up
Recharge the
batteries from
solar
Evening peak -
Provide power after
the sun goes down
Shifting/Dispatching Stored Energy
Simultaneous Shifting and Smoothing
Realized charging times based on weather forecast
Combined PV Smoothing and Shifting Maximizing Benefits from Energy Storage
Simultaneous PV Shifting and Smoothing - 01/14/2013
Entire day of cloudy
PV production needed
to charge battery for
evening peak Firming
Key: Blue=PV Output
Yellow = Battery Output
Red=System Output
Effective Smoothing
using Low Pass Filter
Peak Shaving Results - 06 13 13 Results
~0.7MW reduction in
Sewer Plant Load
during peak – 15%
reduction
~0.7MW reduction in
Sewer Plant Load
during peak – 15%
reduction
•Peak Shaving coincides with target feeder
•Target feeder had been peaking in evening (due to HPPV) but predictive
elements in the algorithm forecasted an earlier peak (due to forecasted
clouds/temps)
•Peak shaving real effect seen on the physically connected feeder (Sewer
plant) - 15% target reduction apparent
Prosperity Output
Prosperity Local
Feeder Load
Prosperity Local Feeder Load Shape
Without Storage
Next Steps: PV Smoothing with Gas Engine to optimize battery life
• Control parameters already implemented. Can tune the tradeoffs between battery use and ramp rates
Test Plan 1 – Smoothing Methodology used
• Battery life can be extended by reducing the variability by the gas engine. Benefits
• Opportunity to coordinate operation of a gas engine and a battery for smoothing PV plant output
MicroGrid & Energy Storage
Reference: Sandia Report SAND2-13-1603. “PV Output Smoothing using a Battery and Natural Gas Engine-Generator”
Public Outreach
Real time data presentation
Presentations
Publications
Education & Outreach
Articles
• Mid School Friday technical projects for Espanola School District – via NNMC
• Project data and analysis used in wide curriculum at NNMC and UNM
• Project engrained in Graduate and PhD studies at UNM Engineering
• 8 IEEE and ASES Smart Grid Technical Papers co-authored with UNM and PNM
Student Outreach– UNM and NNMC
• Formal Alignment between PNM, UNM NNMC, SNL and EPRI
• 30 Project presentations at various forums – nationwide and globally
• Over 40 project site tours to local and national stakeholder groups
PNM Outreach
• EPRI Technology Transfer Award -2013
• Over 20 Industry presentations on project results
• Local and national press coverage
Industry Outreach
www.pnm.com/solarstorage
Solar storage
Challenges
Cost is still a major challenge for battery technologies • There has been some storage incentive legislation contemplated at the
national level. A bill introduced (S.1030 – May 2013) by Sen. Wyden (OR) called the Storage 2013 Act to provide investment tax credits. The bill is currently in Committee on Finance. A related bill (H.R.4096) by Rep. Gibson (NY) was introduced in Feb 2012, but not enacted.
• “Stacking benefits” also critical to overcoming this challenge
Optimizing the benefits being provided to the electric grid (both smoothing and shifting) vs. life of the battery asset
Developing control strategies that consider the key variables that affect energy dispatch
Weather forecasting to understand affects on renewable generation and optimize dispatch from battery system
Development of back office control systems to manage these distributed resources
Strategic implications
The project provides a real-world site for development and demonstration of optimized control strategies for both power and energy.
Modeling efforts and the approach of “stacking benefits” of storage help lead to understanding of applications at: • Small Scale – Community energy storage (25 – 100 kW), Electric
Vehicles
• Large Scale – Compressed Air Energy Storage (CAES), Flywheels, Multi MW sized systems
Battery systems are being seen in the industry as a path toward integration of higher amounts of renewable energy as well as a necessity for micro-grid operation.
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