looking ahead – epri r&d – advanced technologies to …
TRANSCRIPT
Aminul Huque, Ph.D. Sr. Project Engineer, Integration of Distributed Renewables, EPRI
Workshop on Achieving High Penetrations of PV
Solar Power International, September 14, 2012
Looking Ahead – EPRI R&D – Advanced Technologies to Manage and Integrate Distributed PV
2 © 2012 Electric Power Research Institute, Inc. All rights reserved.
Inverter – Role in PV Plants?
PV inverter converts DC energy from solar modules in to AC energy and interface the PV system with electricity grid
Inverter Functionality Today What it Can Do Tomorrow ?
• Harvesting maximum power from PV array
• Matching plant output with grid voltage and frequency
• Providing safety by providing unintentional islanding protection
• Providing grid-support for stability
• Improving PV system reliability
• Reducing PV Balance of Plant Cost
DC Power AC Power
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Smart Grid Vision for Advanced Inverters
Smart, Grid-Friendly Distributed Solar and Storage Systems as Beneficial Distribution System Assets
Inverters with smart-grid functionality can double DER capacity on the grid
4 © 2012 Electric Power Research Institute, Inc. All rights reserved.
How to Coordinate with Existing Controls?
5 © 2012 Electric Power Research Institute, Inc. All rights reserved.
Challenge to Integrate Smart Inverters
• Many manufacturers… Many proprietary protocols • Distribution Management Systems in infancy
3Ph lines
1Ph lines
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2011 2010 2012 2009
September 2010 SEP2 Mapping is Launched
December 2011 Phase 2 Common Functions Published
September 2011 SEP2 Mapping Resumes
March 2010 EPRI Publishes Phase 1 Results: Common Functions for DER
June 2010 IEC TC57 WG17 Adopts Common Functions, begins modeling
61850-90-7 Development
December 2010 DNP3.org Releases First Protocol Mapping
DNP3
February 2012 SunSpec.org Releases First ModBus Draft
Addressing Communication Standard Challenge
March 2009 Launch of the Smart DER Communication Initiative
7 © 2012 Electric Power Research Institute, Inc. All rights reserved.
Smart-Grid Ready PV Inverter with Utility Communication
• Three key components – Developing smart-grid ready inverters – Demonstrating utility connectedness with smart-inverter – Demonstrate utility controlled unintentional islanding prevention
8 © 2012 Electric Power Research Institute, Inc. All rights reserved.
Utility Participants
DOE Project Demo Sites EPRI Collaborating Utilities
DTE Energy
SDG&E
National Grid
Hydro One
Xcel Energy KCP&L
AEP
GRE
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• Voltage regulation and reactive support – Volt-VAR control – Power factor setting – Dynamic reactive current support
• Active Power & ramp rate limiting • Volt-watt control • Frequency-watt control • Dynamic response/LV ride-through • Storage inverter specific functions
– Direct charge/discharge management
– Price-based charge/discharge function
– Real power smoothing function – Load and generation following
function • Other Functions…
Inverter Grid Support Functionality
Example Volt-VAR Behavior (EPRI, 1023059)
LVRT in German MV Grid Code
10 © 2012 Electric Power Research Institute, Inc. All rights reserved.
VAR Support
-200
-150
-100
-50
0
50
100
150
200
-400
-300
-200
-100
0
100
200
300
400
9.2 9.205 9.21 9.215 9.22 9.225 9.23 9.235 9.24 9.245 9.25
Curr
ent
(A)
Volta
ge (V
)
Time (s)
Capacitive
Inductive
Grid Voltage
Inverter Current
Finer steps and faster response compared to cap banks
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Active Power Output Settings 100% 25% 75%
050
100150200250300350400450
4.5 6.5 8.5 10.5 12.5 14.5 16.5 18.5 20.5
DC
Volta
ge &
Cur
rent
Time (s)
Vdc Idc Modbus
-400
-300
-200
-100
0
100
200
300
400
AC
Volta
ge &
Cur
rent
Va Ia
390Vdc
3 Phase Output current ramp(only phase A shown)
DC Current ramp for 100%-25%-75% Curtailment
Modbus Signal(not actual voltage)
Modbus Signal(not actual voltage)
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Voltage Sag/Interruption Ride-Through Improving Grid Reliability
-600
-400
-200
0
200
400
600
Volta
ge (V
)
-40
-30
-20
-10
0
10
20
30
40
2.05 2.25 2.45 2.65 2.85 3.05 3.25 3.45 3.65
Curr
ent (
A)
Time (s)
6 Cycle Interuption
Inverter Current
Grid Voltage
Inverter able to ride through momentary interruptions
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Voltage Sag/Interruption Ride-Through
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
0 20 40 60 80 100 120 140 160 180 200
Perc
ent S
ag D
epth
Perc
ent N
omin
al V
olta
ge R
emai
ning
Event Duration (# of cycles @ 60Hz)
L-L (VAB) Sag L-N (1 ph) Sag L-N (all 3 ph) Sag
Above LinesInverter Ride-thru
Below LinesInverter Trips
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Voltage Swell Ride-Through
100%
105%
110%
115%
120%
125%
130%
0 20 40 60 80 100 120 140 160 180 200
Perc
ent V
olta
ge S
wel
l of N
omin
al
Event Duration (# of cycles @ 60Hz)
L-L (VAB) Swell L-N (1 ph) Swell L-N (all 3 ph) Swell
Above LinesInverter Trips
(up to 125% which is limited by test equipment)
Below LinesInverter Ride Thru
15 © 2012 Electric Power Research Institute, Inc. All rights reserved.
High-Resolution System Monitoring
Collect high-resolution (1-sec) DER generation and environmental data Also capture power quality (PQ) events
(Sep 29, 2011)... 13:10 13:11 13:12 13:13 13:140
200
400
600
800
1000
1200
X: 29-Sep-2011 13:11:15Y: 157.9
AC
Pow
er (k
W)
1MW PV System Pow er Production Profile
Local Date & Time (Eastern)
X: 29-Sep-2011 13:11:40Y: 927.6
X: 29-Sep-2011 13:09:55Y: 908.6
X: 29-Sep-2011 13:10:20Y: 165.6
–743kW in 25 sec
(2.9% per sec)
+770kW in 25 sec
(3.0% per sec)
16 © 2012 Electric Power Research Institute, Inc. All rights reserved.
PV output monitored to understand variability High definition monitoring captures 1-sec data on any size PV system
2kW tracker in TX
1MW ground in TN
0.2kW pole in AL
200kW roof in CA
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1MW PV System in Tennessee Solar resource and AC output recorded at 1-sec resolution
Imagery ©2011 DigitalGlobe, GeoEye, U.S. Geological Survey, USDA Farm Service Agency, Map data ©2011 Google
8 Pyranometers • 7 on PV system • 1 on single-module • Plane-of-array • 25° fixed tilt, south
1.0 MWdc • 3.5 acre • Four 260kW inverters • Data from Oct 2011
Pyranometer Single Module
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Solar Resource Calendar – Single Pyranometer December 2011 at 1MW PV site in Tennessee
1 2 3
4 5 6 7 8 9 10
11 12 13 14 15 16 17
18 19 20 21 22 23 24
25 26 27 28 29 30 31
Thu Fri SatSun Mon Tue WedDecember 2011: Tennessee Plane-of-Array Irradiance
Calendar profiles are 1-minute averages derived from 1-sec data
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Feeder Modeling and Impact Analysis
0.9
0.925
0.95
0.975
1
1.025
1.05
0 4 8 12 16 20
Hour
Vo
ltag
e (p
u)
0.9
0.925
0.95
0.975
1
1.025
1.05
0 4 8 12 16 20
Hour
Vo
ltag
e (p
u)PV Feeder Impact Analysis
(OpenDSS)
Feeder Impact Results
with adv functions
without adv functions
Apply Adv Inverter Functions
Detailed Feeder Models
Increase PV Penetration
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DMS – DERMS Conceptual Architecture
Field Devices Distribution SCADA
Substation Devices
•Basic alarms •Displays •Archiving
Advanced Distribution Applications
•Data Management •Operating model •On-line power flow •Volt VAR •Auto restoration
DMS
Advanced Metering
System (AMI)
Outage Management
System (OMS)
Geographic Information
System (GIS)
Enterprise Service
Bus
ESB
DER Interfaces
•DER Monitoring •Smart Inverter Functions
Advanced DER
Applications
•Request VAR support •Request Watt support •Limit generation •DER forecast •Others
DERs
DERMS
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Enhanced DMS Functionality with DERMS
Conventional Functionality
• SCADA • Volt-VAR Optimization • FLISR • Switching Orders • Load Forecast • Peak shaving • Others
Enhanced Functionality • Active distribution
Control • Enhanced VVO • Enhanced FLISR • Microgrid capability • Firm renewables • Market functions • Others
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Preventing Unintentional Islanding
Method Description Effectiveness Cost Compatibility with grid support functions
Passive Monitor terminal voltage for trip conditions, but does not change inverter output to cause changes
Fair to poor, if high speed is needed
$ Good to excellent
Active Actively change inverter output to cause change
Excellent in single inverter cases
$$ Poor to very poor
Communication based
Relies on communication for system awareness
Excellent (?) $$$$ Excellent
Source: Michael Ropp, Northern Plains Power Technologies
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Do We Need New Unintentional Islanding Prevention Method?
Most inverters use active anti-islanding
which rely on the creation of an abnormal voltage to detect island
formation
Key communication based methods?
• Direct transfer trip (DTT)
• Power Line Carrier Permissive (PLCP)
• Synchrophasor-based methods
Cost
Effectiveness
Equipment reliability
Coverage area
Grid support functions are all about correcting
abnormalities in the voltage/frequency to maintain grid stability
Conflicting
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EPRI Smart-Inverter Demonstration Project
Grid Support
Building Advanced Functionality into Inverters
Deploying in Diverse Field Environments
Collaborating – Sharing Plans and Results, Building Industry Knowledgebase
• Detailed insight into who is doing what • Understanding different functions and architectures • Understanding impacts through modeling and monitoring • Take away new tools and resources to use in other cases
• Provide input to shape industry standards and future products
25 © 2012 Electric Power Research Institute, Inc. All rights reserved.
Together…Shaping the Future of Electricity Aminul Huque
[email protected] 865-218-8051