smart inverter grid support functions - national … · power factor control volt / var volt / watt...
TRANSCRIPT
© 2015 Electric Power Research Institute, Inc. All rights reserved.
Aminul Huque, PhD Technical Leader
Inverter Reliability Workshop 2015 NREL Photovoltaic Reliability Workshop – Golden, CO
February 25, 2015
Smart Inverter Grid Support Functions
and Potential Impact on Reliability
2 © 2015 Electric Power Research Institute, Inc. All rights reserved.
Smart Inverters
“There is an immediate need for new solar to be fitted with “smart inverters” to provide necessary voltage support to integrate effectively and prevent costly renovations and reliability impacts” – Western Electric Industry Leaders, Aug 2013
WEIL Western Electric Industry Leaders
3 © 2015 Electric Power Research Institute, Inc. All rights reserved.
DER Interconnection Standards and Guidelines IEEE 1547 and others are recognizing the importance of DER providing grid support …
2005
2011
FERC SGIP (Small Generator Interconnection Procedure)
IEEE 1547-2003 2003
2000 California Rule 21
Updated California Rule 21 (consistent with IEEE 1547-2003)
IEEE 1547a-2014 2014
2015 Updated California Rule 21
(goes far beyond IEEE 1547a-2014)
2018 IEEE 1547rev-201x
DER must disconnect in response to abnormal voltage/frequency condition
Must not actively regulate voltage
Expected to require minimum V/F ride through and voltage and frequency support capability for Bulk and Distribution system reliability
May actively participate in voltage regulation by changing real/reactive power
May modulate active power in response to frequency
DER may also provide ancillary grid services Future standards/interconnection
guidelines
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Smart Inverter Grid Support functions Remote ON/OFF Power Factor Control Volt / var Volt / Watt Frequency /Watt Reactive Power Control Low/ High Voltage and Frequency Ride Through Power Curtailment
Go to www.epri.com and search 3002002233
IEC 61850-90-7 IEC 61850 Object Models for Photovoltaic, Storage, and Other DER inverters Draft Version 10a
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Voltage Regulation by Reactive Power Support
Power factor mode Volt-var mode Active power-power factor mode (Volt/Watt) Reactive power mode
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Volt-Var Function Max Var (vars before watts) Mode; Inverter was operating at rated power
0
10
20
30
40
50
60
70
80
90
100
-80
-60
-40
-20
0
20
40
60
8093
%
94%
95%
96%
97%
98%
99%
100%
101%
102%
103%
104%
105%
106%
107%
kW
kVAR
Voltage (% of Nominal)
kVar (max) Nebland Inverter Settings kW
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Reactive Power Support – Impact on Efficiency
93.0%
93.5%
94.0%
94.5%
95.0%
95.5%
96.0%
-40% -30% -20% -10% 0% 10% 20% 30% 40% 50%
Effic
ienc
y
Reactive Power Output (% of Nominal Power)
75kW Power Level
41kW Power Level
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270
275
280
285
290
295
300
0
20
40
60
80
100
120
0 20 40 60 80 100 120
Aver
age
of 3
Phas
e L-
N V
olta
ges
(V)
Activ
e Po
wer
(kW
)
Time (s)
kW VLN
Volt-Watt Function
0%
20%
40%
60%
80%
100%
120%
0.00
20.00
40.00
60.00
80.00
100.00
120.00
99% 100% 101% 102% 103% 104% 105% 106% 107% 108% 109% 110%M
ax W
att O
utpu
t ( %
of M
ax)
Activ
e Po
wer
(kW
)
Average of 3Phase L-N Voltages as % of VN
kW kVar EUT curve
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Frequency-Watt Function Voltage Step: VN to Target Voltage (up to 108.6% of VN)
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Low Voltage Ride Through
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Active Power Limiting/ Curtailment
100% 75%25% In 4 secondsIn 6 seconds
Demand Response
Generation Curtailment
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Potential Impact on Inverter Reliability
Reactive power support for voltage regulation – increased loss/ increased operating temperature
Active participation in voltage regulation through volt-var mode may increase period of inverter operation at higher current magnitude – potential impact on device life span
Providing reactive power support during night time will significantly increase the operating hours
Industry practice of higher PV array DC to inverter AC ratio will also require the inverter to operate at higher current level for longer duration
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13
Questions
Contact: Aminul Huque, PhD Technical Leader, EPRI 865-218-8051 [email protected]