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Key Messages
PV power plant is a cost-effective energy res
Well designed Grid Friendly PV plant activstabilizes grid and enhances its reliability
PV variability can be managed with existinginfrastructure through forecasting and site diwith minimum impact
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First Solar Utility Scale PV Plant LeaderOver 3GW Completed or In Development (10MW AC 550MW AC Plants)
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Utility Scale PV Power Plant Overview
PV ModuleArrays Inverters
Transformers
Combiner
BoxesPhotovoltaicCombiningSwitchgear
34.5kV (AC) Typical
300 to690V (AC)
1000V (DC)Substation
Gen Tie-line Pow69 to 525kV (AC)
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PV Module
PV ModuleArrays
1000V (DC)
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Combiner Box
Combiner
Boxes
1000V (DC)
Aggregates DC wiring from m(80KW-160KW)
Provides single dc output to i
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1000V (DC)
Inverters
300 to690V (AC)
Utility Scale Solar Plant Inverters
Converts DC power to AC (l
Grid Management Functions
Reactive Power, etc.) UL1741 and IEEE1547 com
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Transformer
Increases low AC voltage to m
AC voltage for Collection SysTransformers
34.5kV (AC) Typical
300 to690V (AC)
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Power Conversion Station (PCS) Inverter & Step-up Transform
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Photovoltaic Combining Switchgear (PVCS)
PhotovoltaicCombiningSwitchgear
34.5kV (AC) Typical
Aggregates AC power from mtransformers (up to 40MW)
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Substation and Generator Tie-line
Substation
Gen Tie-line Pow69 to 525kV (AC)
Provides plant controls, disconnects, andstep up transformer
Delivers electricity to the grid
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TOPAZ SOLAR
Largest utility scale solar plant in
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AGUA CALIEN
Reliable bulk power generation utilizing advanced plant controls and forecas
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COPPER MOUN
Co-located with existing gas combined cycle pow
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GREENOUGH
Displacing the energy requirements of a desalinatio
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Nakorn Ratchasima, Thailand 7
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PHALODI
Providing energy security to India and displacing 1 million tons
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DEWA SOLAR
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PV Plant Variability Agua Caliente July 2013
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Grid Integration and Plant Control Systems
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Source: U.S. Department of Energy. "Benefits of Using Mobile Transformers and Mobile Substations for Rapidly Restoring Electric Service: A Report to the United State"
Conventional C
Generationtop down p
high voltage
voltage line
Typical Convention Generation, Transmission and Distribution System
PowerFlow
PowerFlow
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Source: U.S. Department of Energy. "Benefits of Using Mobile Transformers and Mobile Substations for Rapidly Restoring Electric Service: A Report to the United State"
As load cha
generators respond ins
change its o
Bulk electr
not commo
What happens when load changes? . Generator has to change output
LoadIncrease100kWGenerationIncrease
100kW
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Source: U.S. Department of Energy. "Benefits of Using Mobile Transformers and Mobile Substations for Rapidly Restoring Electric Service: A Report to the United State"
In Practice Aggregated load matters
LoadIncrease100kW
LoadDecrease
500kW
GeneratorDecrease
400kW What really
the changesaggregated
individual l
M lti l G t d C t l A
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Source: Bernd Engel, SMA
Multiple Generators and Control Areas
In grid of reasonable size, multiple genera
are present and are scheduled for dailyoperation
Total Generation = Aggregated Load + L
a Control Area
Must maintain regulating and contingency
reserves to meet control performance andreliability standards
Multiple Loads
Multiple Generators
D il L d F i d G Di h
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Time of Day
0 6 12 18 24
Daily Load Forecasting and Generator Dispatch
Day AheadForecast
Load
Econom
use load
commit
day ahe
G id O D l i h V i bili & U i
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Time of Day
0 6 12 18 24
Grid Operators Deal with Variability & Uncertainty
Day AheadForecast
Load
Use load forecast a
uncertainty in load
generation throughand dispatch opera
ActualLoad
Load Following and Regulation Reserves
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Load Following and Regulation Reserves
Regulation = Actual Load Real-time Forecast LoadLoad Following = Real-time Forecast Load Hourly Schedule
Lo
Ad
(10
Re
Au
adj
oumi
i f S l G id
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Y
Power Systems PGrid Stability & Reliability
Milliseconds to Minutes Hours to Days
Load Balancing
Key Topics Impact of PV Solar on Power Grid
PV solar
intermittency raisesgrid stability andreliability concerns
PV Variability
increasesoperationalcomplexity
Higher
penetratrequiresgrid flex
V i bl G i I i T i
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Variable Generation Integration Topics
Source: Pacific North West Laboratory, Grid Stability; The Challenges of power grid stability. http://eioc.pnnl.gov/research/gridstability.stm
Grid Stability & Reliability
Msec to Minutes Years
Power Systems Planning & Design
Hours to Days
Load Balancing
Milliseconds to Minutes
Grid Stability & Reliability
CONCERN
Add grid controls to support reand grid security
LEARNING
Solar PV generation doesnot contribute to the reliabilitybulk generation
NERC T k F I t itt t R I t t th G id
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NERC Task Force on Intermittent Resources Impact to the Grid
Voltage, VAR control and/or power factor regu
Fault ride through
Real power control, ramping, and curtailment
Primary frequency regulation
Frequency droop response
Short circuit duty control
Modern solar plants can now contribute to threliability and efficiency of grid operationthe following capabilities:
V lt S t P Fl R l
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P
20 kV
Transformer
0,4 kV Conductor House 1House 2
Last 1La
P
Substation
MV Grid
V o
l t a g e
Voltage Support Power Flow Reversal
A l l o w a
b l e
R a n g eDistance
PV
MaximumLoad
Normal FlowVoltage Drop
High Feed-inLow Load
+ Reactive Power
Reverse Flow withPV Reactive Power
Voltage DropHigh Feed-in
Low Load
Reverse FlowVoltage
Violation
PV With Reactive Power Capability Avoids Costly Network Upgrades
Sourc
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Voltage Regulation
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Voltage Regulation
Utility Scale Active Power Control
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Utility Scale Active Power Control
ReducedPower
Grid Integration and Plant Control System
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Grid Integration and Plant Control System
Real-time ControllersSatellite Imagery
Transformer
Inverters
PV ModuleArrays
CombinerBoxes
Power Conversion Station (PCS) Photovoltaic CombiningSwitchgear (PVCS) Substation
Plant SCADA system
Checks gridrequired set
Sends indivieach invertelosses, and p
Controls quout of the PV
All every 100Short TermForecasting
Set Points
Without a Plant Control System
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Without a Plant Control System
InverterCurtailed
Locally
InverterCurtailedLocally
Benefit of Plant Level Control System
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Benefit of Plant Level Control System
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Proprietary plant controller
Dynamic Power Factor Regulation
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Dynamic Power Factor Regulation
Source: Agua Caliente PV Plant in Yuma, Arizona, USA May 23, 2012. ~212MW on-line.
Command Power Factor
Power Factor SetPoint Changedfrom 0.98 to 1.0
Reaches 90%Steady State Valuein ~ 3.2 seconds
InvertersChangeVAr Output
Plant Curtailment Test
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Power Curtailment at Different Levels
Source: Agua Caliente PV Plant in Yuma, Arizona, USA March 13, 2012. ~90MW on-line.
Set PointReduced
Set PointIncreased
Ramp rates betweenset point changesare controlled
Inverters areTurned Down/OFF to curtail
output
Ramp Rate Controls
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Stopping and Starting One Block (30MW)
Source: Agua Caliente PV Plant in Yuma, Arizona, USA March 13, 2012. ~90MW on-line.
Plant Stop Command
Plant Start Command
Inverters areStarted inSequenceInverters are
Turned Off inSequence;Ramp Ratesare Controlled
Frequency Droop Control
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q y p
Plant Controls Support Frequency Droop
Ability to reduce active power in casegrid is overloaded (i.e., highfrequency)When grid needs more generation(i.e., low frequency) renewable plantcannot increase active power unless plant is already curtailedthen it can increase power
Decrease Active PowerCase of High Frequen
Power Plant Fault Ride-Through Behavior
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PV Plants arsupport bothfrequency r
capability levscale inverte
pra
(Source: SMA)
What Makes a PV Plant Grid Friendly?
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y
Variable Generation Integration Topics
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Hours to Days
Load Balancing
g p
Solar Generation is not fu
Adds variability and uncecomplicates daily dispatch
Years
Power Systems Planning & DesignGrid Stability & Reliability
Msec to Minutes Hours to Days
Load Balancing
CONCERN
Integrate forecasting into daily
Improved operating procedurearea, frequent updates, rampin
LEARNING
Net Demand
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Source: SEC Data. 2020 Load and Generation Mix Projected @5.6% annually for illustration purposes only. FS estimate on PV contribution. Actual resource distribution likely to b
Time of Day (Hours)
D a i l y L o a
d
Load (MW)Net Load Curve (MW)
0 12 24
Aggregation Effect Between Plants Reduces Variability
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Single Location
20 Bundled Locations
One-minute Global Irradiance (W/sq.m)
One-minute Global Irradiance (W/sq.m)
Spatial diversity of solar plants reduces aggregated variabilityminimizing grid impact as the number of solar plants increase
Source: Implications of Wide -Area Geographic Diversity for Short- Term Variability of Solar Power; Andrew Mills and Ryan Wiser, Lawrence Berkeley National Lab
Source: H
Impact of Cloud Passage on Plant Output
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As plants become larger high frequency variability redu
NRG/MidAmerican Agua Caliente 290MW ac
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Yum Dat 2,4 39, PPA EPC
First 2008 EPC Projec tSempra El Dorado10MW
North AmericaLargest PV PlantEnbridge Sarnia80 MW
3 . 0 M i l e s
2.0 Miles
http://powerprojects.firstsolar.com/epc2010/AguaCaliente290/Photos/Agua%20Site%20Aerial%20November%202011.jpghttp://powerprojects.firstsolar.com/epc2010/AguaCaliente290/Photos/Agua%20Site%20Aerial%20November%202011.jpghttp://powerprojects.firstsolar.com/epc2010/AguaCaliente290/Photos/Agua%20Site%20Aerial%20November%202011.jpghttp://powerprojects.firstsolar.com/epc2010/AguaCaliente290/Photos/Agua%20Site%20Aerial%20November%202011.jpghttp://powerprojects.firstsolar.com/epc2010/AguaCaliente290/Photos/Agua%20Site%20Aerial%20November%202011.jpghttp://powerprojects.firstsolar.com/epc2010/AguaCaliente290/Photos/Agua%20Site%20Aerial%20November%202011.jpghttp://powerprojects.firstsolar.com/epc2010/AguaCaliente290/Photos/Agua%20Site%20Aerial%20November%202011.jpghttp://powerprojects.firstsolar.com/epc2010/AguaCaliente290/Photos/Agua%20Site%20Aerial%20November%202011.jpghttp://powerprojects.firstsolar.com/epc2010/AguaCaliente290/Photos/Agua%20Site%20Aerial%20November%202011.jpghttp://powerprojects.firstsolar.com/epc2010/AguaCaliente290/Photos/Agua%20Site%20Aerial%20November%202011.jpghttp://powerprojects.firstsolar.com/epc2010/AguaCaliente290/Photos/Agua%20Site%20Aerial%20November%202011.jpghttp://powerprojects.firstsolar.com/epc2010/AguaCaliente290/Photos/Agua%20Site%20Aerial%20November%202011.jpghttp://powerprojects.firstsolar.com/epc2010/AguaCaliente290/Photos/Agua%20Site%20Aerial%20November%202011.jpghttp://powerprojects.firstsolar.com/epc2010/AguaCaliente290/Photos/Agua%20Site%20Aerial%20November%202011.jpghttp://powerprojects.firstsolar.com/epc2010/AguaCaliente290/Photos/Agua%20Site%20Aerial%20November%202011.jpghttp://powerprojects.firstsolar.com/epc2010/AguaCaliente290/Photos/Agua%20Site%20Aerial%20November%202011.jpghttp://powerprojects.firstsolar.com/epc2010/AguaCaliente290/Photos/Agua%20Site%20Aerial%20November%202011.jpghttp://powerprojects.firstsolar.com/epc2010/AguaCaliente290/Photos/Agua%20Site%20Aerial%20November%202011.jpghttp://powerprojects.firstsolar.com/epc2010/AguaCaliente290/Photos/Agua%20Site%20Aerial%20November%202011.jpghttp://powerprojects.firstsolar.com/epc2010/AguaCaliente290/Photos/Agua%20Site%20Aerial%20November%202011.jpghttp://powerprojects.firstsolar.com/epc2010/AguaCaliente290/Photos/Agua%20Site%20Aerial%20November%202011.jpg -
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Variable Generation Integration Topics
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Years
Power Systems Planning & Design
Grid Stability & Reliability
Msec to Minutes Hours to Days
Load Balancing
Years
Power Systems Planning & Design
Variable generation requires gr
CONCERN
Adopt diverse resource portfolincrease flexibility and reduce
LEARNING
Complementing the Power Portfolio
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Solar is a hedge against fuel price volatility
Power System Planning and Design
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LeananGe
Hours of Operation / Year
S
y s
t e m
L o a
d
Base Load
Generation
Mid-Merit
Generation
Peaking
Generation
System Load
Mid-Merit
Generation
Base Load
Generation
Peaking
Generation
Gas GT
Gas CCGT
Coal
Hydro
Variable generation has impact onlow and minimum load conditions
Addition of varaible generation:Net Load Duration Curve becomesmore steep
Solar generationreduces peak load
Requires a generation mix with more operationalflexibility to serve the net load
(SoNet System Load with VG
California 20% Renewables and Growing to 33%
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Operators have managed high penetration. Others can leverage this learniCAISO Testimony in 2010 CPUC LTPP Docket No. R.10-05-006; July 1, 2011; Exhibit 1, slide 5; trajectory scenario
Successfully integrated renewables today
Building toward 33% reenergy
0
5000
10000
15000
20000
25000
2006 (~10%) 2012 (20%) 2020 E (33%)
GWh
Dispatchable RenewablesWindSolar
Typical Load, Solar and Wind Generating Mar
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Source: CAISOMatt BurkhartSDGE, SemprFeb 13,2013Solar Power G
Net Load and Flexible Capacity Needs
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Source: CAISOMatt BurkhartSDGE, SemprFeb 13,2013Solar Power G
Study needed to determine shape of Flexibility Supply Curve and QuantifyFlexibility Supply Curve
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Sources o
LowCost
HighCost
Markets
FlexibleGeneration
TraditionalStorage
Wind/SolarCurtailment
Storage
In Range of1 or 2%
Hydro with DamsPumped Hydro
Gas StorageSimple Cycle GTCombined CycleSome Coal PlantsReal-Time
Hour AheadDay-AheadPrice Responsive LoadAncillary Service
Conclusions
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Modern PV plants can contribute actively to grid streliability
PV variability can be managed without significant i
existing grid infrastructure through site diversity anforecasting
PV power plants offer a cost-effective energy resou
Lessons learned to date on Renewable Integration Large-scale PV has been successfully integrated in
worldwide No reported issues due to often cited barriers: PV v
harmonics, DC current injection, anti-islanding faiprotection coordination
Bulk energy storage has not been necessary for vargeneration integration
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