Voltage and Var Control Applications
Transcript of Voltage and Var Control Applications
Voltage and Var Control ApplicationsIncluding Smart Inverters, Energy Storage, and Secondary Side Solutions
Dr. Arindam Maitra, EPRIDr. Jason Taylor, EPRI
IEEE PES Meeting, DenverJuly 29th, 2015
1
Uncertainty and Future of the Distribution System
Industry IssueDistribution Planning and Operations are Becoming More Complex
• Traditional methods of managing voltage and reactive power rely on voltage regulators and capacitor banks
• New requirements like peak demand reduction, VVO/CVR for load management are requiring new coordination challenges
• Emerging DER along edge of the n/w
• Autonomous units not well-coordinated with conventional capacitors, voltage regulators and load-tap changers
VVO/CVRProcessor
RTU
End of Line Voltage
Feedback
Standalone
Model-based
Rule-based
Cap banks, Vreg
Cap banks, Vreg, plus Smart inverters
Challenges
Distributed generation• Potential for localized high voltages• Limited visibility of conditions• Fast variations in generation output
Volt/var OptimizationConservation voltage reduction (CVR)
Integration of new distributed voltage controls
Distance from Substation
Volta
ge
• Replace xfmr
• Reconductor
• Line Tap Changer (LTC)
• Cap bank
• Line regulators
Traditional Regulation OptionsBenefits of CVR and VVO:- Lower losses in lines, transformers - Lower losses in end-use devices- Allows more real-power throughput
Volta
ge
Distance from Substation
Upper Threshold
Lower Threshold
Volt/Var Optimization
Grid Impacts of Intermittent Distributed Resources
Source: EPRI
Smart Inverters
Storage
Power Electronic Devices
Potential Benefits– Faster response– Flatter voltage profile– Direct placement for localized problems
Distributed Voltage Regulation
Numerous Potential Performance Objective(s)
Efficiency• Reduced distribution line losses• Improved customer efficiency CVR• Peak Demand reduction
Power Quality
• Flatter voltage profile• Improved harmonics• Voltage flicker• Overvoltage
Asset Utilization
• Reduce LTC tap changes• Reduce line regulator tap changes• Reduce switch cap changes• Deferment of system upgrades
Reliability• Momentary interruption support• Automatic reconfiguration support
Enabling • Increased DER hosting capacity
Smart Inverters
Reactive power dispatch – Output constrained by active power
generation– Multiple control configurations (settings)
Industry Adoption • IEEE standard 1547• California Rule 21 • Manufacturers onboard
0 5 10 15 20 25
1.024
1.026
1.028
1.03
1.032
1.034
1.036
1.038
1.04
1.042
1.044
Hour
Vol
tage
(pu)
---- Voltvar
---- No PV---- PV base
What is the best voltage response?
Depends on the objective
Response using different volt-var settings
Capacitor switching or inverter status change
Control Settings Specification depends upon…
Control Design SensitivitiesTime-series, stochastic assessments• Spatial variation• Temporal variation
performance objective
network characteristics
inverter rating
… as well as Operational Conditions
Formulation of control design practices is needed
Energy Storage Four-quadrant Operation• Voltage regulation using both active
and reactive power
Test Feeder Evaluation• Large voltage variations due to PV
• Storage to provide voltage regulation
• Various deployments considered
PV systems for 57305 feeder
PV Systems for 57307 feeder
Regulator
Substation and meter
Capacitors
PV system
Distance measured from the meter
1.6 miles
1.612 miles
1.579 miles
1.273 miles
1.148 miles
Effect of Energy Storage Location on Voltage
0 0.05 0.1 0.15 0.2
PV Ramp UP
PV Ramp DOWN
Largest Voltage variation (%)
With Energy Storage No Energy Storage
0 0.5 1 1.5 2
PV Ramp UP
PV Ramp DOWN
Largest Voltage variation (%)
With Energy Storage No Energy Storage
0 0.5 1 1.5
PV Ramp UP
PV Ramp DOWN
Largest Voltage variation (%)
With Energy Storage No Energy Storage
0 0.5 1 1.5
PV Ramp UP
PV Ramp DOWN
Largest Voltage variation (%)
With Energy Storage No Energy Storage
The voltage profile improves for each bus. The largest voltage variations at PV buses decrease from 0.014 puto 0.002 pu.
At PV Bus 2
At PV Bus 1
At Feeder End 1
At Substation
210kW/735kWh450kW/1575kWh
2.14MW/7.6MWh
Energy Storage absorbs or generates only active power (Volt/Watt Control)
Effect of Energy Storage Location on Voltage Regulation
00.20.40.60.8
11.21.41.6
Largest voltage variation at PV Bus 2
PV Ramping Up PV Ramping Down
Storage Location
Larg
est v
olta
ge v
aria
tion
(%)
The voltage regulation concerns are demonstrated using PV bus 2
As ES moves away from PV location, the improvement in voltage variation decreases.
PVBus_2
PVBus_1
Energy Storage absorbs or generates only reactive power (Volt-Var Control)
Parameters that Impact ES siting – Voltage Management
Effect on Volt-Watt control Volt-Var Control
Voltage regulation Efficient in regulating voltage Efficient in regulatingvoltage
Losses Depends upon X/R ratio of the feeder
Depends upon X/R ratio of the feeder
Stacked benefits May require oversizing to meet both peak load management
and voltage regulation concerns
Can provide stacked benefits
Life-Cycle cost Decreases due to cycling of battery
Not affected
Smart inverter cost Not required Required to supply vars
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
Redu
ctio
n in
Vol
tage
Var
iatio
n (%
)
Storage Location
Active Power Reactive Power
General Study Circuit FindingsImpacts are location and circuit
specific• Distance from PV• System strength• X/R ratio
Active power injection or absorption may better counteract the variations in RES output
Voltage at PV Bus 2
Increasing distance from Substation
Cap BankSubstation
(LTC)
distribution line LVR
0.9
0.92
0.94
0.96
0.98
1
1.02
1.04
#1 #3 #5 #7 #9 #11 #13
volta
ge
highest voltage
lowest voltage
varia
tion
over
tim
e
Limited voltage control
Centralized Control
Distributed Secondary Side Volt-VAR Control
Secondary Side Control
0.9
0.92
0.94
0.96
0.98
1
1.02
1.04
#1 #3 #5 #7 #9 #11 #13
volta
ge
Improved voltage control
Distributed Control
Cap BankSubstation
(LTC)
distribution line LVR
Distributed Secondary Side Volt-VAR Control
Secondary Side Control
Example Secondary Side Voltage Management SolutionsENGO-V10 (Varentec) Shunt connected 240V, 1-phase 0-10 kvar (leading) Voltage and power factor
control 60/50 Hz
IPR-50 (GridCo) In-line Power RegulatorTM
240V, 1-phase 50 kVA Regulation ±10% ±5 kvar 60 Hz
Example European DevicesPCS 100 AVR (ABB) Active Voltage Regulator (AVR) 400 V, 3-phase 400 kVA 50 Hz ± 10% correction Regulation accuracy ± 1 (typical)
LVRSysTM (a-eberie) Low Voltage Regulator System 400 V, 3-phase 55 – 400 kVA 50 Hz ± 6% (± 10% extended range) 9 steps, 1.5% (2.5%)
Continuing EffortsModeling and Simulation• Models of emerging devices• Simulation capabilities for advanced distribution automation• Actual circuit evaluations• Model validation
Planning & Design
• Impact (coordination) with existing (other) voltage regulation components• Coordination/integration with DMS• Determination of control settings practices• Device location and sizing practices