Almacenamiento de energía y control mediante SCADA
Transcript of Almacenamiento de energía y control mediante SCADA
-
7/25/2019 Almacenamiento de energa y control mediante SCADA
1/6
-
7/25/2019 Almacenamiento de energa y control mediante SCADA
2/6
50 IEEEpower & energy magazine march/april 2010
significant improvement with the addition of distributed
intelligence in conjunction with multiple-MVA/multiple
MWh batteries for energy storage located in or near utility
substations.
Islanding for Improved ReliabilityIslanding is a scheme on the electric grid to isolate and ener-
gize sections of the grid with a local energy source in the event
of a power outage. This energy source may be from a fossil
fuel supply or from advanced technologies such as fuel cells
or energy storage batteries. The ability to island is extremely
beneficial when power from utility supply is lost, typically dur-
ing natural disturbances or when a fault occurs on the electric
system. This ability improves reliability and ensures that cus-
tomer service interruptions are kept to a minimum.
This islanding benefit is of significant value to the electric
utility, especially in areas with frequent electrical outages.
Areas that will benefit considerably from islanding include
load centers fed by old, long lines
areas with dense vegetation (vegetation can come in
contact with electric lines and may cause interrup-
tions)
locations subject to frequent natural disturbances like
tornadoes and storms.
The ability to island is of great benefit because the res-
toration process can be time-consuming. The challenges
encountered in the restoration process include assembling
restoration crews regardless of time of day; locating the fault,
which can be extremely difficult because electric lines may
stretch for several miles; and actually repairing and restor-
ing to service the faulted electric service line or component.
While this extensive process is taking place, the customers
being served by that electric service line are without power,
sometimes for many hours. Islanding, however, creates the
ability to have most if not all of those customers served by a
local source while the restoration effort is ongoing. There are
other benefits that can be realized from islanding as well.
The Islanding Value PropositionReliability data are of great significance to the electric utility,
as they help gauge its ability to provide consistent and depend-
able service to its customers. These data are taken into account,
and plans are made to improve service to areas considered
deficient. In addition, electric utilities are required to provide
electric service reliability data to their respective public utili-
ties commissions (PUCs). This enables PUCs to pressure utili-
ties to improve service reliability. Thus, it is imperative that
utilities maximize reliability across the electric grid.
Numerous benefits accrue from the ability to intelligentlyisland sections of the grid when a fault occurs, including
those listed here.
Improved reliability indices: Reliability indices
such as the customer average interruption duration in-
dex (CAIDI) and system average interruption duration
index (SAIDI) are standard measures of reliability
used to determine the dependability of electric util-
ity service. Islanding can significantly improve these
indices, as fewer customers will be without power and
service interruptions will be shorter.
Resource optimization: Islanding allows prioriti-
zation of the restoration process by allowing limit-ed human and physical resources to concentrate on
nonislanded areas first. Islanding will save human
and financial resources, as crews may not need to
be dispatched to islanded regions during nighttime
hours and paid higher overtime rates. Depending
on the nature of the outage, they may be able to
handle the restoration as part of their normal daily
schedules.
Capital deferral: Islanding can provide an im-
mediate fix for a problematic network and allows
traditional solutions (station construction and/or
enlargement, transmission extension, and distribu-
Station
Energized
Disconnected
figure 1.ADI.
Station
Station
Low Load: Feed All Loads
Energized
Disconnected
figure 2.Selection of individual customer loads athigh-load periods.
Station
Zone 2Zone 1
figure 3.DDI.
-
7/25/2019 Almacenamiento de energa y control mediante SCADA
3/6
march/april 2010 IEEEpower & energy magazine 51
tion feeder enhancement) to be deferred until the
grid can be redesignated to alleviate the problems.
Approaches to IslandingGiven the benefits from islanding outlined above, the ques-
tion becomes, What is the most practical way to actually
achieve islanding? In analyzing a number of ways to pro-
ceed in order to solve several specific issues affecting three
applications where islanding of stored energy might actu-
ally be justified, AEP considered two distinct load manage-
ment methodologies for achieving islanding of distributed
resources. These are 1) adaptive dynamic islanding (ADI)
and 2) discrete dynamic islanding (DDI).
Adaptive Dynamic IslandingADI relies on the utilitys ability to turn on or turn off indi-
vidual customer loads remotely through the use of advanced
metering infrastructure (AMI). Once AMI is sufficiently
deployed, the adaptive approach to dynamic islanding willbecome reasonably practical in terms of implementation and
control (see Figures 1 and 2).
The promise of ADI is that, given sufficient development
and deployment of AMI technology, the utility will be able
to treat each customers load as an island. Once a sufficiently
high level of AMI penetration is reached, every customers
electric meter will be able to be controlled remotely. Thus
certain critical loads such as hospitals, police stations, and
firehouses could be given priority in the event of electrical
power outages. In similar fashion, it would be possible for
less-critical customer loads to be cycled during the inter-
ruption in order to share the available power and socialize
the benefits from islanding while spreading the inconve-
nience of interruptions equitably within the island.
Figure 1 illustrates conceptually how the battery man-
agement system could selectively de-energize or cycle some
customer loads while ensuring higher-priority services
remained energized as long as possible.
Figure 2 illustrates how the ability to remotely connect and
disconnect individual loads will let the energy storage system
intelligently manage the load being supplied in order to opti-
mize the size of the island being served while respecting the
magnitude of stored energy available. Islanding could essen-
tially eliminate interruptions from outages that occur dur-
ing off-peak times, while service interruptions at peak timeswould be mitigated, depending on the duration of the outage.
In the ADI scheme it would be very simple to adjust the
number of customers connected based on the total available
energy in the battery.
At low-load times, the batterys capacity would be ade-
quate to energize the entire section of grid in the island. For
Milton Substation13834.5 kV, 25 MVA
Balls Gap Feeder34.5 kVSummer 200513.7 MVACustomers = 3,204
Grassy Fork Substation13834.5 kV, 25 MVA
Grassy Fork Feeder34.5 kVSummer 200513.7 MVACustomers = 2,950
Future Multiphase Tie toGrassy Fork/Yawkey FeederOnce New Station Exists
Potential AutomatedSectionalizing Points
Rough Path for 8 mi, 138 kV SpurRequired to Feed New Balls Gap Station
Potential or ExistingRecloser Locations
Milton/Grassy Fork Feeders
Selected Site forBalls Gap Station;DESS Location UntilNew Sub Is Completed
figure 4.Balls Gap/Grassy Fork feeder one-line diagram.
-
7/25/2019 Almacenamiento de energa y control mediante SCADA
4/6
52 IEEEpower & energy magazine march/april 2010
situations in which the battery could not energize the entire
section, however, select loads would be energized and/or
cycled as depicted in Figure 2.
Since the penetration of AMI devices was not sufficient
to allow implementation of ADI (at least in the areas where
it could potentially be justified), AEP looked for a practical
alternative to provide the needed level of load control over a
section of the network.
Discrete Dynamic Islanding
DDI describes the ability to connect and disconnect dis-creet sections or zones of the grid (feeder sections) instead
of individual customers, as in the ADI scheme described
above. Thus, each section of the grid that becomes islanded
will include several residential and/or commercial buildings.
This type of islanding is made possible through the use of
advanced communication and control systems that employ
distributed intelligence spread among the feeders sectional-
izing and protective devices that then communicate directly
with each other to automatically isolate faults and restore
service to unfaulted line sections. This method of island-
ing proved to be easier and quicker to implement, as the
core technology and the requisite hardware were currently
available. AEP decided to implement this method in order to
more quickly evaluate the benefits of islanding technology
as a whole. It is also of interest to note that DDI would only
tend to complement ADI if and when the requisite AMI tech-
nologies are in place. Both methods effectively accomplish
the goals of islanding for faults upstream of the island, but
DDI is mandatory if islanding is to be supported during any
faults that occur inside the island. Only DDI has the inherent
ability to detect and automatically isolate faults.
Figure 3 shows the discrete (zonal) approach to load con-
trol and management based on total load in each feeder sec-tion at the time of an outage and the magnitude of stored
energy available from the battery. These two variables are
managed based on the projected time for feeder restoration.
The balance of this article will focus on the practical
application of islanding and look in detail at the islanding
technology selected. AEP implemented three projects to
evaluate the practical benefits of islanding. The details of
one of the projects, the Balls Gap feeder, will be discussed.
Overview of Islanding ProjectsFor each site AEP selected a multi-MW sodium sulfide (NaS)
battery as the stored energy source. The sites are distributed
Not IntelliTEAM
Milton Station
IntelliTEAM
1
63 A120
F8 F9
SW663 A63 A63 A
SW363 A63 A63 A F2
52 A11
F4000
F3000
F1
SW411 A11 A11 A
SW511 A11 A11 A
F57 A522
SW24 A4 A4 A
SW83 A3 A3 A
F73 A330
F61 A523SW7
0 A0 A0 A
SW10 A0 A0 A
0 A1202
Balls Gap DESS
Single PhaseReclosers
Logo Copyright AEP.Columbus. OH
Note: When src side field
is source color and Ld side fieldis gray, it indicates one phase
of recloser has opened.
651 R
651 R
figure 5.Balls Gap feeder one-line diagram.
Islanding is a scheme on the electric grid to isolateand energize sections of the grid with a local energy sourcein the event of a power outage.
-
7/25/2019 Almacenamiento de energa y control mediante SCADA
5/6
march/april 2010 IEEEpower & energy magazine 53
over AEPs service territory and are located respectively in
West Virginia (Balls Gap), Ohio (Bluffton), and Indiana (East
Busco); the sites share the common characteristic that the
feeders where the batteries are to be deployed are all radi-
ally fed, with no readily accessible source of alternate supply.
Each battery is rated for 2 MW at 7.2 MWh, indicating that
the battery can supply 2 MW of power for up to seven hours,
assuming the battery is fully charged at the time of an event.
This also indicates that the feeder devices to be used for the
islanding are located so as to carve out a 2-MW block of load,
with additional smart switches added to allow the island-
ing scheme to shed load once islanding has occurred for long
enough to partially deplete the energy in the NaS battery.
The feeder devices incorporated into the various island-
ing schemes include intelligent sectionalizing switches in
addition to two popular intelligent electronic device (IED)
reclosers. And while the distributed automation (DA) scheme
selected has been performing well for over a decade, its use
for islanding does represent new tech-nology and the chance to learn how DA
devices perform in new applications.
In view of the pioneering aspect of
these projects, an in-depth study of each
islanding application was undertaken to
investigate various technical challenges
associated with the use of NaS technol-
ogy and recommend measures to deal with
each challenge. Included in the studies
were in-depth coordination studies, load-
ing and historical fault data analyses, and
feeder modeling to verify islanding perfor-mance under real-world scenarios.
Balls Gap (West Virginia)Islanding ProjectOf the three projects undertaken by
AEP in 2009, the Balls Gap project was
the most complex. For this particular
application, there were various obstacles
to using stored energy to mitigate service
interruptions that had to be dealt with in
an extremely challenging environment.
The Balls Gap feeder includes a roughly35-mile-long, 34.5-kV overhead radial
feeder that runs through the Appalachian
Mountains southeast of Milton, West
Virginia, where the distribution substa-
tion is located (see Figure 4).
Since this is a radially fed circuit with
no possible ties to an alternate source, per-
manent outages tend to last for hours, given
the many challenges of getting resources
to the area. But an analysis of loading and
historical fault data indicated that the vast
majority of faults that resulted in a lock-
out of the breaker occurred upstream of the first recloser
shown above and that roughly 2 MVA of load exists below
this recloser. Since this fairly closely matched the size of the
batteries AEP was planning to install, the Balls Gap feeder
began to come into focus as an appropriate candidate for
evaluating the costs and benefits of applying NaS technology
for islanding purposes.
Although no alternate three-phase connection other than
the Milton station is available, small single-phase links to
similarly sized single-phase lines served from the Grassy
Creek station do exist. The long-term plan is thus to bolster
the stability of service in the entire region by installing a new
station and upgrading the stringy single-phase lines to three-
phase trunks that will connect the new Balls Gap station to
the existing station at Grassy Creek. In addition, eight miles
of 138-kV transmission line will have to be run, again through
the rolling mountains that saturate the area. With siting,
acquisition of rights-of-way, and construction planning, the
(d)
(a) (b) (c)
figure 6.Feeder devices involved in islanding: (a) smart DA switch withIED control Networking radio, (b) recloser A IED control, with modulenetworking radio, (c) recloser B IED control, with module networking radio,and (d) PCS (interior view showing power electronics and system controls).
(Images courtesy of AEP).
-
7/25/2019 Almacenamiento de energa y control mediante SCADA
6/6
54 IEEEpower & energy magazine march/april 2010
transmission spur is a four-to-five-year effort under normal
planning horizons, during which time the customers servedfrom the Balls Gap feeder would see essentially no relief from
the lengthy interruptions that typically occur when a perma-
nent fault takes the Balls Gap feeder breaker to lockout.
During the site preparation, the Balls Gap feeder was
analyzed to determine the number of and locations for feeder
devices that would work together to create and maintain the
island during periods when the battery becomes isolated from
the Milton station by an upstream fault. A simplified one-
line diagram showing the portion of the feeder that includes
the 2 MVA of customer loads intended to benefit from the
DESS is shown below in Figure 5. Six feeder devices (two
reclosers and four sectionalizing switches) were deployedat crucial locations in order to apportion the total load into
logical groups with roughly equal demands.
For faults upstream of the first automated feeder device
(Sw-3), all of the downstream devices will open on loss of
source (LOS) and report this to the other devices. Knowing
that all of the DA devices are open, the module at the power
conditioning system (PCS) will close Sw-1 to energize
the first section of line to Sw-7. Knowing that all devices
opened on LOS, the DA scheme has only to quantify how
much load is being picked up as each line section is ener-
gized relative to how much capacity the NaS battery was
telling the interface module it could supply when the eventfirst began. The DA scheme keeps track of this capacity as
the transfer progresses, ensuring that the capacity of the
NaS battery is never exceeded.
For faults that occur within the island, so long as the fault
does not occur in the line sections between the DESS and the
main trunk of the circuit (between Sw-1 and Sw-4 and Sw-5),
the DA scheme will automatically isolate the fault and restore
service either from the DESS or from the Milton substation,
depending on the faults exact location. In this scenario it is
important to note that the Milton substation will continue to
serve as much of its normal load as possible, something not
previously possible for faults this far out on the feeder. This
functionality is unique to the DDI approach and leverages
the ability of the distributed intelligence of the DA scheme to
derive added benefit from the islanding technology.
A variety of smart feeder IEDs were incorporated into the
open-architecture DA scheme over the three distinct island-
ing projects, as is illustrated in Figure 6. These included the
power conditioning system (PCS) used to convert the NaS
battery energy to AC power suitable for injection into the util-
ity grid.
Commissioning of each of the DESS islanding applica-
tions was performed by AEP by bypassing each of the feederdevices and then simulating an LOS from the normal feed of
supply. For each site, the loss of source voltage was simu-
lated to test system performance. The planning engineer for
the Balls Gap project, however, wanted to get an even higher
level of confidence that the scheme was ready to work. A test
was formulated whereby at a designated time a load break
switch just ahead of the island would be opened to create an
actual LOS scenario. The test went precisely as planned, and
the NaS battery picked up all the customers in the island. The
final system installation is shown in Figure 7.
ConclusionsIn actual operation, the system at Balls Gap did require minor
adjustment in the sensing circuits to ensure proper coordina-
tion of the reclosers and automated feeder switches. Actual
islanding events have occurred with successful operation of
the batteries in islanding mode. Based on the three projects
discussed in this article, AEP has undertaken an even larger
project to be completed in 2010.
For Further ReadingA. Nourai and C. Schafer, Changing the electricity game,
IEEE Power Energy Mag., vol. 7, no. 4, pp. 4247.
B. Roberts, Capturing grid power, IEEE Power EnergyMag., vol. 7, no. 4, pp. 3241.
A. Nourai. (2009, Nov. 1). Utility-scale energy storage
migrates toward the grid edge [Online]. Available: www.
tdworld.com
BiographiesAli Nourai is the manager of energy storage programs at
AEP and chairman of the board for the Electricity Storage
Association.
David Kearnsis application director, smart grid technol-
ogies, for the Automated Systems Division of S&C Electric
Company. p&e
figure 7.Balls Gap energy storage system installation.(Photo courtesy of AEP.)
DDI describes the ability to connect and disconnectdiscreet sections or zones of the grid (feeder sections)instead of individual customers.