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Modeling the Effects of Integrating Distributed Energy Resources with the Electric Power System
Modeling the Effects of Integrating
Distributed Energy Resources with the
Electric Power System
Subcontract No. NAD-1-30605-01
Presented by Nick Miller
GE Global Research Center
GE Power Systems Energy Consulting
Puget Sound Energy
NREL Technical Monitor:
B. Kroposki
Principal Investigator:
Z. Ye
Senior Technical Advisors: N. Miller
R. Delmerico
R. Walling Grid 2030 Roadmap: DG is a Key Technology
GE interconnect project is performing crucial investigation of DG and EPS
integration issues
(Support OETD system integration goal)
Quantitative insight into the critical issues
Results are useful to the industry in defining interconnection standards GE proposed a systematic approach to addressing interconnect solutions
(Support OETD Interconnection cost reduction goal)
Reduce hassle factor in the interconnection process through pre-testing and
pre-certification of standard-compliant interconnects.
Achieve full benefits and value for DG through a universal interconnect platform
with modular, scalable and progressive functionalities. Bulk Power System, Backbone , Issues are More Important than Ever
Understanding is essential for DR to achieve its full potential
Introduction WSCC
Disturbance at
Palo Verde NPS (3000+ MW)
Malin
Path 15
Colstrip
Raver-
Paul Line
Case Study - DR Impact on Bulk Power System
Substation Bus
Incoming Circuits
Equivalent Load:
P
L
+ jQ
L
[MW & MVAr]
Base Case Load
Bus Representation
Adding DG
Incoming Circuits
Equivalent Load:
P
L
(1 + DG
pene
) + jQ
L
(1 + DG
pene
)
DG + Load
Bus Representation
~
Equivalent DG:
P
DG
= P
L
(DG
pene
)
Substation Bus
>6000 DGs
Modeled: 0.9950
0.9960
0.9970
0.9980
0.9990
1.0000
1.0010
1.0020
1.0030
1.0040
1.0050
0.00000
Time, sec.
20.0000
label1
Wed Sep 19 14:34:33 2001
a:ai\0-ip-paloverde-ai.chf
b:ai\20-ip-paloverde-nai.chf
c:ai\20-ip-paloverde-ai.chf
0.9950
a
o
spd 62049 COLSTP 2 22.00 1
1.0050
o
o
o
o
o
0.9950
b
+
spd 62049 COLSTP 2 22.00 1
1.0050
+
+
+
+
+
0.9950
c
*
spd 62049 COLSTP 2 22.00 1
1.0050
*
*
*
*
*
WESTERN SYSTEMS COORDINATING COUNCIL
2000-01 HW1A-OP
Current file selected from 3 different files
Active Anti-Islanding Impact on Bulk Power System
Red: base condition without DG
Green: 20% DG penetration
Blue: 20% and with active anti-islanding
Disturbance event:
a very large power station
with multiple units generating
over 3000 MW in WSCC
system is assumed to be
tripped off-line by some
common-mode disturbance.
The case illustrates that the
aggregate impact of the
active anti-islanding scheme
is benign to the system
performance
The lack of frequency
regulation by DGs
aggravates the common-
mode frequency depression
Bulk System frequency dynamics with high DG Penetration and impact of Anti-islanding
-0.3Hz
+0.3Hz Bulk system voltage dynamics with low voltage DG tripping (20% DG penetration).
0.6000
0.6600
0.7200
0.7800
0.8400
0.9000
0.9600
1.0200
1.0800
1.1400
1.2000
0.00000
Time, sec.
20.0000
label1
Wed Sep 19 15:12:53 2001
a:ai\20-ip-paloverde-nai.chf
b:vtrip\20-pv-vtrip70.chf
c:vtrip\20-vtrip90.chf
0.6000
a
o
vbus 40687 MALIN 500.00 1
1.2000
o
o
o
o
o
0.6000
b
+
vbus 40687 MALIN 500.00 1
1.2000
+
+
+
+
+
0.6000
c
*
vbus 40687 MALIN 500.00 1
1.2000
*
*
WESTERN SYSTEMS COORDINATING COUNCIL
2000-01 HW1A-OP
Current file selected from 3 different files
Red: base condition no under voltage tripping
Green: under voltage tripping (set point 70%)
Blue: under voltage tripping (set point 90%)
Voltage at the
500kV Malin bus
DG Tripping impact on Bulk System Stability
P1547 standard dictates
disconnect for voltages <88%
within 2 seconds.
It is important to note that this
specifies the minimum voltage
and the maximum time to trip.
Thus, DGs will be in violation if
they trip slower or at too low a
voltage. However, the DGs may
trip faster and at higher voltages
than this without violation.
The case (blue trace) with the
90% trip point is very unstable
120% V
60% V
88% V P1547 Voltage Response 88% voltage mandatory
trip of DR per P1547*
For illustration: Mapping of voltage from 500kV
down to individual DR may result in tripping
sooner or later depending on system topology
August 14, 2003: EHV Transmission Voltages P1547 Frequency Response P1547 Over-
frequency trip point
August 14, 2003: Frequency Europe and much of the rest of the world is moving towards a variety of
grid codes, in which a set of performance requirements are imposed on
the windfarm, largely independent of the site.
Requirements for most North American applications are being governed
by the power system requirements particular to that site but grid codes
are likely to follow soon.
Drawing on industry experience with wind generation
Response to voltage
events has emerged as
THE critical issue What is Low-Voltage Ride-Through (LVRT)?
The increased ability of wind-turbine generators to tolerate
and continue operation after voltage dips those voltage
depressions that occur during grid faults. Why LVRT now?
Wind Farms are becoming important contributors to
the operation of the bulk power system
:
For grid reliability, requirements for continuity of power
from wind generation are increasing.
The historical desire to have WTGs that are embedded in
distribution systems trip quickly is no longer the norm.
Wind is a victim of its own success what can the DG
community learn? Statutory Response of WTGs to Emergency Voltage (e-ON example)
0.00
0.10
0.20
0.30
0.40
0.50
0.60
0.70
0.80
0.90
1.00
1.10
1.20
1.30
1.40
1.50
0.0
0.1
1.0
10.0
100.0
1000.0
10000.0
Time (seconds)
Volt
ag
e (PU
)
Wind Generation Must NOT TRIP
Wind Generation Must NOT TRIP
Wind Generation MAY TRIP
Wind Generation MAY TRIP P1547 Response of DRs to Emergency Voltage
0.00
0.10
0.20
0.30
0.40
0.50
0.60
0.70
0.80
0.90
1.00
1.10
1.20
1.30
1.40
1.50
0.0
0.1
1.0
10.0
100.0
1000.0
10000.0
Time (seconds)
Volt
ag
e (PU
)
DR MUST TRIP
DR MUST TRIP
DR MUST TRIP
DR MUST TRIP
DR MAY TRIP Statutory Response of WTGs to Emergency Voltage (e-ON example)
v.s. 1547
0.00
0.10
0.20
0.30
0.40
0.50
0.60
0.70
0.80
0.90
1.00
1.10
1.20
1.30
1.40
1.50
0.0
0.1
1.0
10.0
100.0
1000.0
10000.0
Time (seconds)
Volt
ag
e (PU
)
Mutually Exclusive Requirements
Wind is a being aggressively pushed to stay on-line Collector Bus
Utility
Transmission
Bus (POI)
Individual WTG
Crisp voltage regulation in
weak systems is essential
45 mi
SCR ~3.5
~10 mi
Another emerging issue: Voltage Regulation
DG in physically remote and/or weak systems must
participate Another emerging issue: Voltage Regulation
Voltages and Flows at
Utility Point-of-
Interconnection:
Farm supervisory
control meets
system
requirements
Comparison: with (red)
vs. without (black)
0.90
0.94
0.98
1.02
1.06
1.10
0
150
300
450
600
Utility Transmission Bus Voltage (pu)
Time (seconds)
-10
0
10
20
30
40
Total Wind Farm Reactive Power (MVAr)
0
40
80
120
160
200
0
150
300
450
600
Total Wind Farm Power (MW)
Time (seconds)
5
7
9
11
13
15
WTG Wind Speed (m/sec)
Utility System Variables
Very clean
voltage on
the host
utility grid
bus Making the correct choices now provides for the future of DG
Summary
The power system isnt infinite; big events do happen
Dynamics matter; control philosophy is important
Local concerns dont necessarily jibe with systemic (backbone)
requirements
For DG a key issue will be good citizenship
Advanced Anti-Islanding concepts are needed to maximize
system benefits
GE project is focused on critical technology issues and
building on experiences in related technology