Power through Policy
DOE-EERE “Wind and Water Power Program”-funded Project - Power Through Policy: Best Practices for Cost-Effective Distributed Wind
Quantitatively identify distributed wind policy best practices using a pro forma model.
Target audience: state-level decision makers Project team includes private, government, and academic sectors of the industry:
PNNLNRELeFormative OptionsNorth Carolina Solar Center
DeliverablesDistributed Wind Policy Comparison Tool Guidebook
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Distributed Wind Policy Comparison ToolUser only needs to select two inputs initially:
State Sector
Model is then populated with default values based on these inputs
DSIRE quantitative data feed for policies and incentivesDefault values can be changed by user
Model calculates Cost of Energy (COE)Project Net Present Value (NPV)Project Internal Rate of Return (IRR)Simple Payback
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Distributed Wind Policy Comparison Tool
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Sign up to receive an announcement when the tool goes live online: www.eformativeoptions.com/dwpolicytool.html
Model Design Challenges
Incentives are Changed FrequentlyWisconsin – complex to opaqueVermont – complex to simpleMaryland – combinedNew Jersey – on holdCalifornia – on hold
Incentive Program Designs are All DifferentCapital Cost Rebates
Capacity-based or Production-based or BothFlat rates or incremental ratesExpected performance or actual performance
Production-Based IncentivesUpfront rebate or given over time
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Case Studies
Ranking of StatesBased on policies as of April 2011Ranking based on averaging the sectors’ economic results for each state:
Residential: 2.4 kWResidential / Farm: 10 kWNon-Taxed: 50 kW Commercial: 100 kW
Net Metering Example: Massachusetts & Texas
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State Rankings: Top 10 and Bottom 10
$0.00 $0.05 $0.10 $0.15 $0.20 $0.25 $0.30 $0.35
TennesseeMississippi
IndianaIllinois
West VirginiaSouth Carolina
PennsylvaniaMichigan
FloridaConnecticut
ColoradoCaliforniaMarylandMontana
New JerseyVermont
New YorkMassachusetts
NevadaOregon
COE ($/kWh)
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Net Metering
State policy
Voluntary utility program(s) only
www.dsireusa.org / February 2011
* State policy applies to certain utility types only (e.g., investor-owned utilities)
WA: 100
OR: 25/2,000*
CA: 1,000*
MT: 50*
NV: 1,000*
UT: 25/2,000*
AZ: no limit*
ND: 100*
NM: 80,000*
WY: 25*
HI: 100KIUC: 50
CO: no limitco-ops & munis: 10/25
OK: 100*
MN: 40
LA: 25/300
AR: 25/300
MI: 150*WI: 20*
MO: 100
IA: 500*
IN: 10*IL: 40*
FL: 2,000*
KY: 30*
OH: no limit*
GA: 10/100WV: 25/50/500/2,000
NC: 1,000*
VT: 20/250/2,200
VA: 20/500*
NH: 100MA: 60/1,000/2,000/10,000*
RI: 1,650/2,250/3,500*
CT: 2,000*NY: 10/25/500/2,000*PA: 50/3,000/5,000*NJ: no limit*
DE: 25/100/2,000co-ops & munis: 25/100/500
MD: 2,000
DC: 1,000
Note: Numbers indicate individual system capacity limit in kW. Some limits vary by customer type, technology and/or application. Other limits might also apply. This map generally does not address statutory changes until administrative rules have been adopted to implement such changes.
NE: 25
KS: 25/200*
ME: 660co-ops & munis: 100
PR: 25/1,000
AK: 25*
43 states + DC & PR have adopted a net
metering policy
DC
DSIRE Net Metering Map as of February 2011
State-wide net metering
Net Metering – Massachusetts &Texas
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A state is considered to have state-wide net metering in model if IOUs, electric cooperatives, and municipalities ALL allow net metering
16 states without asterisks on the previous mapOnly IOUs in MA are obligated to provide net meteringOnly voluntary net metering programs in TX
Sector Texas Massachusetts
Net Present Value (NPV)
Without net metering
With net metering
Without net metering
With net metering
Residential ($11,913) ($7,389) $698 $5,038
Residential / Farm ($37,814) ($24,132) ($12,808) $57
Non-Taxed ($260,184) ($105,224) ($93,840) $82,608
Commercial ($222,438) ($38,706) ($177,161) $23,706
Texas: Modest improvementAssume net metering is at retail cost of electricity
Commercial / Non-Taxed Entities: $0.1075/kWhResidential: $0.1304/kWh
Massachusetts: Great improvementAssume net metering is at retail cost of electricity
Commercial / Non-Taxed Entities: $0.158/kWhResidential: $0.1768/kWh
Great for areas that already have net metering, but…There are no electric co-ops in MA, so a state-wide net metering policy would only affect municipal utilities.Are there sufficient wind resources in urban municipalities?
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Net Metering – Massachusetts &Texas
Summary
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Tool can be used by policy makers and incentive managers to
Play “what if” game by adjusting default inputs and current incentivesDetermine what incentives really improve the bottom line
Going ForwardDSIRE data feed is keeping up with incentive changesTool and Guidebook will be published June 2011
Growing the Small Wind Market Through Testing and Certification
Brent Summerville, Technical DirectorSmall Wind Certification Council
TM
SWCC: Small Wind Certification Council
New independent, third-party certification body to serve North America
Certify that small wind turbines (SWTs) meet the requirements of the new AWEA Small Wind Turbine Performance and Safety Standard
Used as incentive eligibility
TM
Problem
Small turbine performance specifications are not standardized
Agencies and utilities providing financial assistance are asking for performance assurance to increase support for incentives
Consumers need greater certainty of function, performance, and durability
Less than half of turbine models on the market have been tested
TMwww.greentechmedia.com
California
Inaccurate performance ratings (Power) Suspension of $3/watt rebate in March,
stakeholder meeting in April
TM
New Jersey
REIP, Renewable Energy Incentive Program (rebate based on expected kWh)
Field failures = suspend program in March and call a stakeholder meeting in April
www.njcleanenergy.com
TM
Why Certification?
Allow consumer comparison of products
Funding agencies will gain greater confidence that small turbines installed with public assistance have been tested for safety, function, performance and durability and meet requirements of consensus standards
Consumer protection and industry credibility
TM
Trend: Require certification for incentives
Energy Trust of Oregon Focus on Energy (Wisconsin) New York State Energy Research and
Development Authority (NYSERDA) Massachusetts Clean Energy Center
(MassCEC) California Energy Commission (CEC) Colorado, Iowa, Maine, Maryland,
Minnesota, Nevada, Vermont New Jersey?
TM
UK/MCS leading the way
8 turbines now on the MCS list
www.microgenerationcertification.org
TM
SWCC Certification Pending ApplicantsAmerican Zephyr Corporation Airdolphin GTO Under TestBergey Windpower Co. Bergey 5kW Under ContractBergey Windpower Co. Bergey Excel-S Under TestBRI Energy Solutions, Ltd Vbine 10-05 Under ContractEndurance Wind Power Inc. Endurance S-343 Under ContractEnertech, Inc. Enertech E13 Under ContractEvance Wind Turbines Ltd. Evance R9000 Conditional Temp CertEveready Diversified Products Kestrel e400i 3kW 250V & 48Vdc Under ContractEvoco Energy Evoco 10kW Conditional Temp CertGaia Wind Ltd. GW 133-11kW Certified Under MCSPolaris America LLC P15-50 & P10-20 Under ContractPotencia Industrial S.A. 10kW Hummingbird Under ContractRenewegy, LLC Renewegy VP-20 Under ContractSeaforth Energy AOC 15-50 Under ContractSouthwest Windpower Skystream 3.7 Conditional Temp CertTaisei Techno Co. TTK-10kW Under ContractTalk, Inc. Suelflow 100 Under ContractUrban Green Energy UGE-1k and UGE-4k Under ContractUrWind UrWind O2 Under TestVentera Energy Corporation Ventera VT10 Under TestWindspire Energy Windspire – 800040 Under ContractXzeres Wind Corporation Xzeres-442SR Certified Under MCS
TM
Trend: Status reporting
SWCC Status reporting Previous Application Pending Conditional Temporary Certification Certified
New Under Contract Under Test Reports Submitted Limited Power Performance Certification Conditional Temporary Certification Certified
TM
Product Development Scenarios
1. “The Short Circuit”
2. Certification
Dream up a wind turbine
design
Build one, see if it works
Sell to customers
Revise design based on customer problems
Dream up a wind turbine
design
Build one, see if it works;
thorough shakedown
testing
Test and Certify to Standards
Sell to Customers
TM
Trend: “Cash flow hybrid”
Dream up a wind turbine
design
Build one, see if it works;
thorough shakedown
testing
Test and Certify to Standards
Sell to Customers
TM
Certification to AWEA vs.MCS Certification in the UK
MCS Certification to BWEA
Required Limited Design Evaluation Power Performance Safety and Function Duration Acoustic Noise (reporting
differs) Factory Production Control
SWCC Certification to AWEA
Required Limited Design Evaluation Power Performance Safety and Function Duration Acoustic Noise (reporting
differs)
TM
Trend: Reciprocity
UK and North America Harmonization of BWEA/AWEA Standards Example: Acoustics
Testing performed per IEC 61400-11 with some modifications Analyzed for
AWEA Standard
Analyzed for BWEA
Standard
TM
Trend: Installer Certification
North American Board of Certified Energy Practitioners (NABCEP) has certified 1st round of installerswww.nabcep.org
SWCC certifies Mechanical Strength, Durability, Function & Performance of turbine systemto the AWEA standard
NRTLs certify Electrical Safety of Turbine &Controller (new UL Standards in development)
PE certifies Tower & Foundation
NABCEP certifies the Installer
NRTLs certify Inverterto IEEE 1547/UL 1741
Wired per National Electrical Code (NEC) (new in 2011)
Grid-t
ie S
mal
l W
ind T
urb
ine
in t
he
US
Advanced Controls that Optimize Variable Speed Stall Regulated TurbinesJim StoverVice President, Product ManagementWindpower 2011
©2009. Northern Power Systems. All Rights Reserved. Not to be used or shared without permission. Proprietary and Confidential.
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Community Wind Technology Needs
Improved Efficiency in Low Winds
Low Maintenance
Utility Friendly:
• High Power Quality• Net Metering Ready
Simplified Installation
Low Noise
Aesthetic Fit with Surroundings
©2009. Northern Power Systems. All Rights Reserved. Not to be used or shared without permission. Proprietary and Confidential.
DOE Support for Permanent Magnet Direct Drive (PMDD) Development
DOE and NREL support for advanced drivetrain development
• Permanent magnet generators
• Full active power converters
• Digital signal processing (DSP) based platform simultaneously controls both turbine operation and power converter
WindPact and LWST: NPS 2.3 in MichiganMidsize Program: NPS 450 Under Development
McKay Photo
DWT Program: NPS 100 at McGlynn Elementary
©2009. Northern Power Systems. All Rights Reserved. Not to be used or shared without permission. Proprietary and Confidential.
Geared Drivetrain
Generator GearboxBearing & CouplingPower
Converter
Bearing & Coupling
1/3 moving parts = lower up-front cost, high reliability and lower O&M
No gearbox replacements (20 yrs = 4,000,000 miles on a transmission)
Variable speed torque control of “digital drivetrain” captures max power
Low noise and better power quality for utility interconnect
GeneratorPower
Converter
Direct Drive
Variable Speed, Stall Control Permanent Magnet Direct Drive: Efficiency, Simplicity and Max AEP
Pitch Bearings & Motors
Fixed Pitch
©2009. Northern Power Systems. All Rights Reserved. Not to be used or shared without permission. Proprietary and Confidential.
DOE Distributed Wind Turbine (DWT) Program Results…
100kW rated power
• 30 or 37m tower, 21m rotor
• Fixed pitch, variable speed
Meets Customer needs
• Low maintenance (1 visit per year)
• 24/7 SCADA monitoring
• Low noise for permitting
• Easy utility interconnection
• Simplified installation logistics
Design certification
• Certified to CE, UL, CSA safety and performance standards
• Power curve and noise validated by DNV to IEC standards
Community Wind: typically local power; “inside the meter”;
competes with retail-level economics
©2009. Northern Power Systems. All Rights Reserved. Not to be used or shared without permission. Proprietary and Confidential.
Wind Power Basics: Extracting Energy…
Betz Limit• Maximum portion of the power in a wind
stream that can be extracted• Cp max = 59.26%
Blade dynamics• Incoming wind speed (V)
combined with bladerotational speed determines aerodynamics and sum to driving force of rotor (Fd)
• Tip Speed Ratio (TSR) = blade rotational speed over wind speed
• To optimize angle of attack along the blade it must twist from root to tip
• Stall occurs as angle of attack increases and TSR decreases at high V
©2009. Northern Power Systems. All Rights Reserved. Not to be used or shared without permission. Proprietary and Confidential.
Wind Turbine Design Challenge: Maximize Efficiency While Maintaining High Wind Control
Power in Wind: P = 0.5ρACpV3
• P = Power• ρ = mass density of air• A = area swept by the rotor blades• Cp = power coefficient• V = wind speed
Ptarget = 0.5ρACp target (R/TSRtarget)3ω3
• R = rotor radius measured at the blade tip• TSR = Tip Speed Ratio = ωR/V • ω = rotational speed of the blade
Optimizing power• As wind speed changes, rotor speed should
adjust to maintain optimum TSR and Cp, until maximum tip speed (65-75 m/s) is reached
• BUT, wind speed is not a good control parameter - it is erratic and there are measurement delays
Ref.: Control Strategy for Variable-Speed, Stall-Regulated Wind Turbines, NREL/CP-500-24311 - UC Category: 1211, E. Muljadi, K. Pierce, P. Migliore
©2009. Northern Power Systems. All Rights Reserved. Not to be used or shared without permission. Proprietary and Confidential.
“Digital Drivetrain” Enables Fast Response and Maximum Power Tracking
From above, Ptarget is a function of RPM
Permanent magnet generator and full active power converter• Extract electrical torque (current)
to control RPM • Sized to contain wind gusts at
rated power
Advanced DSP controls provide superior torque control• Fast response to wind fluctuations • Sets RPM to track Max Cp over
low and medium wind speeds• Actively manages stall in high
winds
Generator & Converter limit RPM, increasing blade angle of attack
and creating stall
©2009. Northern Power Systems. All Rights Reserved. Not to be used or shared without permission. Proprietary and Confidential.
Overview Of Variable Speed Turbine Control
Blade profilematching powerand speed data
TurbinePerformanceCompensationAlgorithm
Speed-loop closedloop controller
MeasuredPower
Measuredspeed
SpeedCmd1 SpeedCmd2
Torque/current
command
Powercmd
Speed Loop Controller: hosted on DSP and samples > 10,000 times per second to calculate optimum torque command for instantaneous conditions
Turbine Performance Compensation Algorithm: compensates for blade performance, air density and other site conditions
©2009. Northern Power Systems. All Rights Reserved. Not to be used or shared without permission. Proprietary and Confidential.
0
2
4
6
8
10
12
14
16
18
0
20
40
60
80
100
120
25 45 65 85 105 125
Win
d S
pee
d (
m/s
)
Po
wer
(kW
), R
oto
r S
pee
d (
RP
M)
Sample time
Real Time Controller Performance
Power Converter extracts current from the generator per optimum torque calculation
Fast response delivers maximum power tracking and optimal performance
Efficiency of a pitch regulated turbine without the added cost, complexity or ongoing maintenance of a pitch subsystem
More current is drawn to slow the
rotor in gustsLess is drawn to
maintain rotor speed when winds are falling
©2009. Northern Power Systems. All Rights Reserved. Not to be used or shared without permission. Proprietary and Confidential.
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Additional Benefits Include Improved Grid Power Quality and Active Tower Damping
Tower Damping: Advanced active tower damping reduces fatigue
Power Quality: Smooth power transfer to the grid
Site Optimization: Line voltage correction
Site Optimization: Air Density Compensation
©2009. Northern Power Systems. All Rights Reserved. Not to be used or shared without permission. Proprietary and Confidential.
Tower damping reduces mechanical resonance by controlling rotor torque
Control algorithm can also provide damping to any minor blade imbalances
Active Tower Resonance Damping Reduces Fatigue and Enables Use of a Lighter, More Cost-Effective Tower
Without Tower Damping
Active Tower Damping
Up to 10 x reduction in tower motion
©2009. Northern Power Systems. All Rights Reserved. Not to be used or shared without permission. Proprietary and Confidential.
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Design Objectives of Taller “Soft” Tower: Greater Energy Capture and Lower Installation Costs
Less weight = lower cost; greater height = more energy capture
Three section nested design simplifies shipping: single 40’ flatbed truck
Installation with a common 60-ton truck crane
“Stiff” Tower “Soft” Tower % Change
Tower Height 30m 37m +23%
Tower Weight 13,800kg 13,100kg -5%
Fundamental Frequency
1.2 Hz 0.8 Hz
©2009. Northern Power Systems. All Rights Reserved. Not to be used or shared without permission. Proprietary and Confidential.
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Power Quality Comparison of a Converter-Connected Turbine vs. and Induction Turbine
Reactive power (Northern Power 100 provides +/- 45kVAR with or without wind) can be used to support grid voltage
No inrush current on turbine startup – avoids voltage dip on local grid
Better behavior on weaker and distributed grids
0%
50%
100%
150%
200%
10 15 20 25 30 35 40 45 50
Time (Seconds)
App
aren
t Pow
er (k
VA
)
Asynchronous generator
Northern Power 100
©2009. Northern Power Systems. All Rights Reserved. Not to be used or shared without permission. Proprietary and Confidential.
-50
-40
-30
-20
-10
0
10
20
30
40
50
98.0%
99.0%
100.0%
101.0%
102.0%
103.0%
104.0%
105.0%
106.0%
107.0%
0 11 21 31 41 51 61 71 81 91 101 111 121
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Site Optimization: Site Utility Voltage SupportExample of using Reactive Power +/- 42kVAR in raising or lowering site Voltage by up to 2.5% to improve site conditions (example only)
Demonstration below performed at Barre, Vermont - performance is highly site specific and can be tuned on a case-by-case basis
Grid Voltage
Reactive Power
Time (seconds)
1. Reactive Power command of -42 kVAR
drives grid voltage down by 2.5%
2. Similar increase in Reactive Power
command of +42 kVARbrings grid voltage up
©2009. Northern Power Systems. All Rights Reserved. Not to be used or shared without permission. Proprietary and Confidential.
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0
20
40
60
80
100
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Site Optimization: Air Density Compensation
Auto-tuning of rotor speed to maintain control and maximize power in colder temperatures: -3C, winds varying 9-15m/s over 4.5 hours
Power (kW)
Rotor RPM
Wind Speed (scaled)
2. As wind peaks, rotor speed limits to maintain control
3. Rotor returns to full RPM to maximize power as wind
dies down
1. At full RPM, power converter extracts more
Current as wind rises
©2009. Northern Power Systems. All Rights Reserved. Not to be used or shared without permission. Proprietary and Confidential.
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SmartView SCADA: Access to All Real-Time Data for Performance Enhancement and Optimization
©2009. Northern Power Systems. All Rights Reserved. Not to be used or shared without permission. Proprietary and Confidential.
Distributed Applications Demand Sophisticated Performance from a Reliable Machine
Customer Need Pitch StallPMDD Variable Speed
Stall Benefit
Low Up-Front CostBetter ROI / More green energy
Energy CaptureBetter ROI / More green energy
Low O&MReliable, Low Cost Performance
Utility FriendlyBetter Power Quality and Easier Interconnect
NoiseLower RPM, Lower Noise, Easier Permitting
Efficiency of a pitch regulated turbine without the added cost, complexity, or ongoing maintenance of pitch subsystem
©2009. Northern Power Systems. All Rights Reserved. Not to be used or shared without permission. Proprietary and Confidential.
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Thank You
Jim StoverVice President Product ManagementNorthern Power Systems29 Pitman RdBarre, VT [email protected]
Please visit: www.northernpower.com