Distribution System Analysis for Smart Grid Roger C. Dugan Sr. Technical Executive, EPRI Webcast Feb 8, 2011
Distribution System Analysis for Smart Grid
Roger C. DuganSr. Technical Executive, EPRI
Webcast
Feb 8, 2011
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OPENSG-SIMSWG Feb 2011
EPRI Power Systems Modeling/Analysis Group
• Resource group -- systems modeling, simulation, analysis
• Consulting services from generation to end-use
• Resource support for R&D collaborative efforts
– Transmission planning
– Operations
– Distribution planning and operations
– Substation design
– Power quality
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The Smart Grid
• SG is different things to different people
– Communications and control
• Typically not represented in DSA (at present)
– Distributed Resources
• Generation, Storage, Demand Response
– Test Feeders WG has done large induction machines
– Monitoring
– Protection
– Energy Efficiency
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Smart Grid Features
• Distributed Resources
– Generation
– Renewable Generation
• Variable sources
– Energy Storage
– Demand Response
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Smart Grid Features, cont’d
• Communications and Control
– AMI deployed throughout the system
– High-speed communications to Metering and Controls
– State Estimation
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Impact of SG on Distribution System Analysis?
• What DSA framework is needed to support all features of the SG?
• Will there be a need for DSA if everything is monitored thoroughly?
• What could we do if we know more about the system?
• How will merging of planning, monitoring and DSE change DSA tools?
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Role of Distribution System Analysis
• Distribution state estimation
• Emergency reconfiguration
– Account for missing data, failed comm
• EPRI vision
– Planning and DMS will converge into one set of tools (Real time and planning will merge)
• Continued need for DSA tools
– Different form and more capabilities
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Advanced Simulation Platform -- OpenDSS
• Open source of EPRI’s Distribution System Simulator (DSS)
– developed in 1997
– open sourced in 2008 to collaborate with other research projects
• OpenDSS designed to capture
– Time-specific benefits and
– Location-specific benefits
• Differentiating features
– full multiphase model
– numerous solution modes
– “dynamic” power flow
– system controls
– flexible load models
• Needed for analysis of
– DG/renewables
– energy efficiency
– PHEV/EV
– non-typical loadshapes
Download for free from
http://sourceforge.net/projects/electricdss
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Computing Annual Losses
Peak load losses are not necessarily indicative of annual losses
0
10
20
30
40
50
60
70
Lo
ad
, M
W
1
5
9
13
17
21
Jan Ap
r Jul
Oct
0
5000
10000
15000
20000
25000
kWh
Hour
Month
Year 5 Losses: total 2413 MWh
20000-25000
15000-20000
10000-15000
5000-10000
0-5000
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Overall Model Concept
Control
Center
Control
Power Conversion
Element
("Black Box")
Inf. Bus
(Voltage, Angle)
Comm
Msg Queue 1
Comm
Msg Queue 2
Power Delivery
System
Supporting Renewables
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Solar PV Simulation 1-hr Intervals
-1
0
1
2
3
4
5
2 Weeks
MW
-1
0
1
2
3
4
5
Dif
fere
nce,
MW
Without PV With PV
Difference
Peak is not reduced
What is the Capacity Gain?
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Can DMS Enable Increased Capacity?
-1
0
1
2
3
4
5
2 Weeks
MW
-1
0
1
2
3
4
5
Dif
fere
nce,
MW
Without PV With PV
Difference
Shorter Duration
Of Peak
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Cloud Transients: 1-sec Interval
1-Sec Solar PV Output Shape with Cloud Transients
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
0 500 1000 1500 2000 2500 3000
Time,s
Pe
r U
nit
of
Ma
xim
um
Impact on Feeder Voltage
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Solar Ramping
Basic Solar Ramp Function
Regulators compensate for drop
Voltage Pushed over limit on recovery
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Regulator Response for Series of Cloud Transients
Regulator Operations
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“Headroom” for PV
Voltage Profile for 100% Load
Voltage Profile for 40% Load
Use DMS to Regulate Lower to
Allow More “Headroom” for DG
More efficient, too??
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Steady-State Voltage
Primary Bus Voltages - Base Case
0.95
0.975
1
1.025
1.05
1.075
0 0.5 1 1.5 2 2.5 3 3.5 4 4.5
distance from substation (mi)
per-
un
it v
olt
ag
e
V(1)
V(2)
V(3)
• Maximum change in voltage
• PV at increased penetration until limit exceeded
• Use of volt/var control accommodates added PV before violations occur
10% PV
Voltage Change
0
0.005
0.01
0.015
0.02
0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5
distance from substation (mi)
per-
un
it v
olt
ag
e
deltaV(1)
deltaV(2)
deltaV(3)
15% PV
Voltage Change
0
0.005
0.01
0.015
0.02
0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5
distance from substation (mi)
per-
un
it v
olt
ag
e
deltaV(1)
deltaV(2)
deltaV(3)
20% PV
Voltage Change
0
0.005
0.01
0.015
0.02
0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5
distance from substation (mi)
per-
un
it v
olt
ag
e
deltaV(1)
deltaV(2)
deltaV(3)
20% PV with VVC
Voltage Change
0
0.005
0.01
0.015
0.02
0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5
distance from substation (mi)
per-
un
it v
olt
ag
e
deltaV(1)
deltaV(2)
deltaV(3)
Device Locations / Voltage
638000 640000 642000
X
185000.00
186000.00
187000.00
188000.00
189000.00
Y
Baseline – No PV
10% PV
15% PV
20% PV
20% PV and VVC
PV
VAnalysis results from other
feeders indicate 25%-100%
more PV can be
accommodated using VVC
Substation
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Primary Voltage Response with Volt/Var Control
12 kV Voltage
0.9
0.925
0.95
0.975
1
1.025
1.05
0 4 8 12 16 20
Hour
V (
pu
)
Baseline – No PV
20% PV
20% PV w/ volt-var control
Storage
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Generic Storage Element Model(OpenDSS Model)
% Eff. Charge/DischargeIdle | Discharge | Charge
Idling Losses
kW, kvar
kWh
STORED
Other Key
Properties
% Reserve
kWhRated
kWhStored
%Stored
kWRated
etc.
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Controlling Storage from DMS
Discharge Mode
Charge Mode
kW Target
Discharge Time
Total Fleet kW Capacity
Total Fleet kWh
et. al.
Storage “Fleet”Substation
V, IComm Link
Time + Discharge rate
Peak Shaving
Load Following
Loadshape
Substation controller/DMS
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Load Shapes With and Without Storage
Mode=Peak Shave, Target=8000 kW, Storage=75 kWh
Charge=2:00 @ 30%
0
1000
2000
3000
4000
5000
6000
7000
8000
9000
10000
0 50 100 150 200 250 300
Hours
kW
0
10
20
30
40
50
60
70
80
Base kW
Net kW
kWh Stored
Simple Substation Peak Shaving
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Load Shapes With and Without Storage
Mode=Load Follow, Time=14:00, Storage=25 kWh
Charge=2:00 @ 30%
0
1000
2000
3000
4000
5000
6000
7000
8000
9000
10000
0 50 100 150 200 250 300
Hours
kW
0
5
10
15
20
25
30
Base kW
Net kW
kWh Stored
Attempting Peak Shave Every Day
Too Early
About Right
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Load Shapes With and Without Storage
Mode=Time + fixed rate, Time=14:00 @ 25% Storage=25 kWh
Charge=2:00 @ 30%
0
1000
2000
3000
4000
5000
6000
7000
8000
9000
10000
200 210 220 230 240 250
Hours
kW
0
5
10
15
20
25
30
Base kW
Net kW
kWh Stored
Accounting for Storage Losses
ChargingDIscharging
Charging energy > Discharging energy (compare areas)
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Key Distribution Modeling Capabilities for Smart Grid
• Distributed generation modeling
• Time series simulations
• Efficiency studies
• Meshed networks
• Large systems
• Parallel computing
• Distribution state estimation
• Protective relay simulation
• AMI Load data
• Modeling controllers
• Modeling comm
• Work flow integration
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Key Challenges
• Merging Planning and Real-Time Analysis
• Very Large System Models
• Systems Communications Simulations
• Large Volume of AMI Data
• AMI-based Decision Making
• Time Series Simulations
• Distribution State Estimation
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Key Challenges, Cont’d
• Detailed LV Modeling
• Including multiple feeders, transmission
• DG Integration and Protection
• Generator and Inverter Models
• Meshed (Looped) Network Systems
• Regulatory Time Pressures
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Reference
• R.C. Dugan, R. F. Arritt, T. E. McDermott, S. M. Brahma, K. P. Schneider, “Distribution System Analysis To Support the Smart Grid”, presented at 2010 IEEE PES General Meeting, Minneapolis, MN
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Together…Shaping the Future of Electricity