2014 PV Distribution System Modeling Workshop: Increasing Hosting Capacity with Advanced Inverter...
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Transcript of 2014 PV Distribution System Modeling Workshop: Increasing Hosting Capacity with Advanced Inverter...
Matthew Rylander
Senior Project Engineer
PV Distribution System Modeling Workshop
May 6, 2014
Increasing Hosting Capacity with
Advanced Inverter Functions
2 © 2014 Electric Power Research Institute, Inc. All rights reserved.
Overview
Objective
• Demonstrate, via simulation, higher feeder PV hosting capacity via use of
advanced inverter functions
Outline
• Method for analysis
– Possible PV deployments
– Advanced inverter functions
– Feeder end-use load
– Feeder response metrics
• Analysis results
• Summary of findings
3 © 2014 Electric Power Research Institute, Inc. All rights reserved.
Method for Analysis
Step 1: Create thousands of possible PV deployments
– Utility-scale PV
– Customer-owned PV
Step 2: Run all PV deployments from zero to full output
while holding all controls fixed
– Observe feeder-wide impact
• Voltage Magnitude
• Voltage Deviation
– Repeat for different load conditions
Step 3: Repeat step 2 with advanced inverter functions
4 © 2014 Electric Power Research Institute, Inc. All rights reserved.
Step 1: PV Deployment
Baseline – No PV
20% Customers with PV
30% Customers with PV
50% Customers with PV
Beyond…
PV Systems
Process is
repeated
100’s of times
to capture
many
possible
scenarios
5 © 2014 Electric Power Research Institute, Inc. All rights reserved.
Step 2: PV Impact Analysis
• Voltage Magnitude
– Primary voltage nodes should be < 1.05 Vpu
– Secondary voltage nodes should be < 1.05 Vpu
• Voltage Deviation
– Primary voltage nodes should be < 0.03 Vpu
– Secondary voltage nodes should be < 0.05 Vpu
1.035
1.04
1.045
1.05
1.055
1.06
1.065
1.07
0 0.5 1 1.5 2
Max
imu
m F
ee
de
r V
olt
age
(Vp
u)
Total PV Penetraion of Deployment (MW)
Minimum Hosting Capacity
Maximum Hosting Capacity
A B C
Wo
rst-
Ca
se R
esu
lt fo
r E
ach
Un
iqu
e P
V D
ep
loym
ent
Increasing penetration (MW)
Threshold of violation
A – All penetrations in
this region are
acceptable, regardless
of location
B – Some penetrations
in this region are
acceptable, site specific
C – No penetrations in
this region are
acceptable, regardless
of location
Details on analysis method:
Stochastic Analysis to Determine
Feeder Hosting Capacity for
Distributed Solar PV. EPRI, Palo
Alto, CA: 2012. 1026640.
Ma
xim
um
Fe
ed
er
Vo
lta
ge
s (
pu)
6 © 2014 Electric Power Research Institute, Inc. All rights reserved.
Step 3: Impact of Advanced Inverters
PV at Unity Power Factor PV with Volt/var Control
2500 cases shown
Each point = highest primary voltage
ANSI voltage limit
ANSI voltage limit
Increasing penetration (kW)
Ma
xim
um
Fe
ed
er
Vo
lta
ge
(pu
)
Ma
xim
um
Fe
ed
er
Vo
lta
ge
s (
pu
)
Increasing penetration (kW)
No observable violations regardless of PV size/location
Possible violations based upon PV size/location
Observable violations occur regardless of size/location
Minimum Hosting Capacity Maximum Hosting Capacity Minimum Hosting Capacity Max Hosting Capacity
7 © 2014 Electric Power Research Institute, Inc. All rights reserved.
Advanced Inverter Functions
• Absorbing reactive power at constant power factor
– Unity power factor (Base case, control off)
– 98% power factor
– 95% power factor
• Inverter voltage determines reactive power output
Volt-Var 1 Volt-Var 2
8 © 2014 Electric Power Research Institute, Inc. All rights reserved.
Advanced Inverter Control, cont.
• Inverter voltage determines active power output
• Dynamic control of reactive power output based on voltage
deviation
Volt-Watt 1 Volt-Watt 2
0
100
0.9 0.95 1 1.05 1.1 1.15
Wat
ts G
en
era
ted
(%)
Local Voltage (pu)
0
100
0.9 0.95 1 1.05 1.1 1.15
Wat
ts G
en
era
ted
(%)
Local Voltage (pu)
-50
0
50
-0.2 -0.1 0 0.1 0.2
Re
acti
ve C
urr
ent
(%)
Local Voltage Change (pu)
9 © 2014 Electric Power Research Institute, Inc. All rights reserved.
Utility Feeder
Feeder
Characteristics Feeder
Voltage (kV) 12.47
Peak Load ~ 6 MW
Minimum Load 0.7
Existing PV (MW) 1.7
Substation LTC Yes
Feeder Regulators 3
Capacitors 2 – fixed
3 – voltage controlled
Total Circuit Miles 58
Feeder “Footprint” 35 mi2
Sub
Reg
Cap
10 © 2014 Electric Power Research Institute, Inc. All rights reserved.
Utility-Scale PV at Maximum Load
Primary Voltage Magnitude
• Dyn-Var and Volt-Watt 2 controls help is minimal
• Volt-Watt 1, Volt-Var 1, and 95% pf controls help limit
voltage magnitude
Line indicates
average impact
from all PV
deployments
1.02
1.04
1.06
1.08
1.1
1.12
1.14
1.16
1.18
1.2
1.22
0 2000 4000 6000 8000 10000
Max
imu
m F
ee
de
r V
olt
age
(pu
)
Total PV (kW)
11 © 2014 Electric Power Research Institute, Inc. All rights reserved.
Utility-Scale PV at Maximum Load
Primary Voltage Deviation
• Dyn-Var and Volt-Watt 2 controls help in minimal
• Volt-Watt 1, Volt-Var 1, and 95% pf controls help limit
voltage deviation
12 © 2014 Electric Power Research Institute, Inc. All rights reserved.
Utility-Scale PV at Maximum Load
Feeder Head Demand
• Volt-Watt controls limits PV active power output
• All other controls only impact the reactive power demand
– Bulk power system to provide or local resources
– 95% pf and Volt-Var 1 require the most reactive power
-6000
-4000
-2000
0
2000
4000
6000
8000
0 2000 4000 6000 8000 10000
Feed
er
Po
we
r (k
W)
Total PV (kW)
Control Off 98% pfVolt-Var 1 Volt-Var 295% pf Volt-Watt 1Dyn-Var Volt-Watt 2
-500
0
500
1000
1500
2000
2500
3000
3500
4000
0 2000 4000 6000 8000 10000
Feed
er
Po
we
r (k
var)
Total PV (kW)
Control Off 98% pf
Volt-Var 1 Volt-Var 2
95% pf Volt-Watt 1
Dyn-Var Volt-Watt 2
13 © 2014 Electric Power Research Institute, Inc. All rights reserved.
Utility-Scale PV
Advanced Inverter Summary
0 2000 4000 6000 8000 10000
Control Off
Volt-Var 1
Volt-Var 2
98% pf
95% pf
Volt-Watt 1
Volt-Watt 2
Dyn-Var
Feeder Hosting Capacity (kW)
Co
ntr
ol
No observable violations regardless of PV size/location
Possible violations based upon PV size/location
Observable violations occur regardless of size/location
14 © 2014 Electric Power Research Institute, Inc. All rights reserved.
0 1000 2000 3000 4000 5000
Control Off
Volt-Var 1
Volt-Var 2
98% pf
95% pf
Volt-Watt 1
Volt-Watt 2
Dyn-Var
Feeder Hosting Capacity (kW)
Co
ntr
ol
Customer-Owned PV
Advanced Inverter Summary
No observable violations regardless of PV size/location
Possible violations based upon PV size/location
Observable violations occur regardless of size/location
15 © 2014 Electric Power Research Institute, Inc. All rights reserved.
Potential Adverse Impacts Due to Increased
Var Flow
PV @ Unity
Power Factor
PV @ 0.98
Power Factor
PV @ 0.95
Power Factor
Hosting Capacity Based on
Feeder Overvoltage (kW)
Hosting Capacity Based on
LTC/Line Regulator
Operations (kW)
Increased
hosting capacity Decreased
hosting capacity
0 2000 4000 6000 8000 10000
P3
0 2000 4000 6000 8000 10000
P3
0 2000 4000 6000 8000 10000
P3
0 2000 4000 6000 8000 10000
P3
0 2000 4000 6000 8000 10000
P3
0 2000 4000 6000 8000 10000
P3
No observable violations regardless of PV size/location
Possible violations based upon PV size/location
Observable violations occur regardless of size/location
16 © 2014 Electric Power Research Institute, Inc. All rights reserved.
Inverter Settings are Critical
% A
vaila
ble
Var
s
% voltage
100%
0.95
1.05
-100%
1.0V
% A
vaila
ble
Var
s
% voltage
100%
0.99
1.01
-100%
1.0
Volt-var A
1
1.01
1.02
1.03
1.04
1.05
0 60 120 180 240 300 360 420 480 540
PV
Te
rmin
al V
olt
age
(p
u)
Time (seconds)
1
1.01
1.02
1.03
1.04
1.05
0 60 120 180 240 300 360 420 480 540
PV
Te
rmin
al V
olt
age
(p
u)
Time (seconds)
Unity Power Factor
Volt-var A
Volt-var B
1
1.01
1.02
1.03
1.04
1.05
0 60 120 180 240 300 360 420 480 540
PV
Te
rmin
al V
olt
age
(p
u)
Time (seconds)
If wrong setpoints are used, adverse
impacts can occur
0
0.5
1
PV
Act
ive
P
ow
er
Volt-var B
17 © 2014 Electric Power Research Institute, Inc. All rights reserved.
Summary
• Feeder hosting capacity can increase with advanced
inverter functions
– Volt-Var and off-nominal power factor provides the
greatest benefit
• Volt-Var and power factor control requires reactive power
resources
– Requiring significant reactive power can have adverse
impact
• Inverter settings must be chosen carefully
18 © 2014 Electric Power Research Institute, Inc. All rights reserved.
Together…Shaping the Future of Electricity