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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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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