https://doi.org/10.37815/rte.v36n1.1117
Original Articles
Estudio
comparativo de la respuesta dinámica de tres tipos de sistemas de
almacenamiento de energÃa para estudios de red: Experimentos reales en un
laboratorio de Micro-Red
Danny Ochoa-Correa1 <=
/span>https://orcid.org/0000-0=
001-5633-1480,
Edisson Villa-Ãvila1=
 https://orcid.org/0000-0=
002-2766-5913, Vinicio Iñiguez-Morán1 https://orcid.org/0000-0=
001-7494-191X, Patricio
Astudillo-Salinas
1Uni=
versidad
de Cuenca, Cuenca, Ecuador
danny.ochoac@ucuenca.edu.ec, edisson.villa2809@ucuenca.edu.ec, vinicio.iniguezm@ucuenca.edu.ec, patricio.astudillo@ucuenca.edu.ecÂ
 <=
/span>
Accepted:Â Â Â Â Â Â 2024/06=
/06
Published: Â Â Â Â Â 2024/06=
/30Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â =
Â
Abstract
Summary: Introductio=
n,
Materials and Methods, Results and Discussion and Conclusions. https://rte.espol.edu.ec/index.php/tecnologica/article/view/1117=
Implementing
Energy Storage Systems (ESS) is increasingly significant in power electrical
systems. This is attributed to their ability to store surplus electricity
generated by renewable energy sources such as wind and solar, contributing =
to
the balance between generation and demand. Literature studies indicate that
this practice enhances network stability and diminishes the need for expens=
ive
redesigns in infrastructure. This paper presents an exhaustive
experimentation-based study of the dynamic response provided by three energy
storage system technologies: supercapacitors, Lithium-Ion batteries, and
Vanadium redox flow batteries, technologies with significant academic,
research, and industrial interests nowadays. The objective of this research=
is
the experimental evaluation of the performance of such technologies in real
electrical system operations, focusing on determining the efficiency of cha=
rge
and discharge, as well as the tracking of active and reactive power achieved
through the associated grid interface. The experimental tests performed in a
microgrid laboratory show these technologies’ advantages and limitations =
in
different grid-integration applications, with the Lithium-Ion battery-based=
ESS
demonstrating the highest efficiency and faster power response. The results
achieved and reported in the article can serve as an essential input for
researchers and technology developers to feed their models with more precise
parameters and data that might provide results closer to the actual behaviour of the studied prototypes. The methodologic=
al
framework used in this research is descriptive, experimental, and quantitat=
ive.
=
Keywords: E=
ESs,
Lithium-Ion batteries, Vanadium-redox flow batteries, Supercapacitors,
Microgrids.
Resumen
La implementación de sistemas de almacenamiento de
energÃa (SAE) está adquiriendo una creciente relevancia en los sistemas
eléctricos de potencia. Esto se debe a su capacidad para almacenar el exce=
dente
de electricidad generado por fuentes de energÃa renovable, como la eólica=
y la
solar, y contribuir al equilibrio entre la generación y la demanda. Estudi=
os
documentados en la literatura muestran que esta práctica mejora la estabil=
idad
de la red y reduce la necesidad de realizar costosos rediseños en la
infraestructura. En este artÃculo, se presenta un estudio exhaustivo basad=
o en
la experimentación de la respuesta dinámica proporcionada por tres tecnol=
ogÃas
de SAE: supercapacitores, baterÃas de iones de litio y baterÃas de flujo =
de
Vanadio redox; tecnologÃas de gran importancia en la academia, investigaci=
ón e
industria en la actualidad. El objeto de esta investigación es la evaluaci=
ón
experimental del desempeño de tales tecnologÃas en operaciones reales de =
un
sistema eléctrico, centrándose en la determinación de eficiencia de carg=
a y
descarga, asà como en el seguimiento de potencia activa y reactiva consegu=
ido
por la interfaz de conexión a la red asociada. Los resultados de los
experimentos realizados en un laboratorio de microrred muestran las ventaja=
s y
limitaciones de estas tecnologÃas en diferentes aplicaciones, demostrando =
ser
la más eficiente y rápida en respuesta de potencia el SAE basado en bater=
Ãas de
iones de litio. Los resultados alcanzados y reportados en el artÃculo sirv=
en
como insumo esencial para que los investigadores y desarrolladores de
tecnologÃa alimenten sus modelos con parámetros y datos más precisos que
brinden resultados más cercanos al comportamiento real de los prototipos
estudiados. La metodologÃa utilizada en esta investigación es descriptiva,
experimental y cuantitativa.
Introduction
Over=
view
T=
he
production of electricity from renewable sources  such as solar
and wind energy
is highly dependent
on weather conditions. Solar energy is available only from dawn to dusk,
and cloudy conditions can cause variations in energy production during this time. Likewise,
in the case of wind energy, wind speed is highly variable
in both on-shore and off-shore wind farms, resulting in varying levels of energy production.=
This
variability is a problem for
electrical power systems since energy must
be supplied to consumers (residential, commercial, and primarily industrial) in complianc=
e with
rigorous quality standards concerning voltage level and frequency.
<= o:p>
I=
n this
context, there is a clear need to mitigate the
variability intrinsic to intermittent renewable energy sources (IRE) and
<= o:p>
A=
ccording
to
<= o:p>
Figure 1 shows the uses of batteries,
supercapacitors, and other energy sto=
rage
mechanisms employed at d=
ifferent scales within electrical
systems
<= o:p>
Figure 1
Usage of energy storage systems at differ= ent scales in electrical systems. Source: own elabora= tion based on [4]=
<= o:p>
Stat=
e-of-the-art
review
There is an important academic, research, and industrial interest in
energy storage, given its performance and technological maturity, which is =
why
it is possible to find many scientific contributions that have led to count=
less
applications in the literature. In
In this line, research reported in
In addition, these works explore the opportunities provided by the
concept of “second life†of electrochemical systems decommissioned in t=
heir
original applications (e.g., discarded batteries of electric vehicles) with=
the
consequent reduction of the carbon footprint
This property facilitates the absorption of fluctuations of wind and
photovoltaic generators in weak and isolated power systems, improving the
reliability and quality of the power supply
Apart from the applications mentioned here, energy storage systems
provide a more comprehensive range of implementation opportunities in
electrical power systems to provide support in fundamental activities such =
as
frequency and voltage control in a power grid <=
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ID=3D"368272930">(Zecchino et al., 2021);
Figure 2
Applications
of battery energy storage systems in power systems
Aim =
of the
study
This research aims to experimentally evaluate the performance of ESS
technologies in actual power systems operations, explicitly focusing on
determining the efficiency of charge and discharge processes and analysing the active and reactive power set-point tra=
cking
dynamics achieved through the associated network interface. The study involves an exhaustive exami=
nation,
based on experimentation, of the dynamic response provided by three energy
storage systems (ESS) working on a power system: ESS based on supercapacito=
rs,
ESS based on lithium-ion batteries, and ESS based on Vanadium Redox Flow
Batteries, three technologies of great current interest in the academic,
research and industrial fields. The laboratory tests are designed to yield
characteristic curves and times of the charge and discharge processes of the
different technologies, as well as active and reactive power set-point-trac=
king
dynamics.
<= o:p>
Mate=
rials and
Methods
First of all, this section describes the
materials used for conducting the proposed validations. Subsequently, the
developed methodology and the design of the experiments, which will lead to=
the
achievement of the research objectives, are outlined.
<= o:p>
Mate=
rials:
Energy storage systems under study
Microgrid
Laboratory of the CCTI-B
T=
he
experimental work is conducted in the Microgrid Laboratory of the Centro
<= o:p>
Figure 3
Schematic representation of components of= the Microgrid Laboratory: 1. Main grid, 2. Grid connection bus bar (B-01), 3. Energy storage components, 5. Programmable loads and sources, 6. Other load= s, 7. Solar photovoltaic generation, 8. Wind generation, 9. Thermal = generation, 10. Hydraulic= generation
W=
ithin the
scope of the present study, the Microgrid Laboratory of Universidad de Cuen=
ca
has the following energy storage systems, which constitute the materials us=
ed
in the current research
<= o:p>
·
ESS
based on supercapacitors (Supercapacitors- ESS)
·
ESS
based on lithium-ion batteries (Li-Ion BESS)
·
ESS
based on Vanadium Redox Flow Battery (Vanadium Redox Flow - BESS)
Supercapacitors–ESS
S=
upercapacitors
(SCs) are storage devices capable of holding more energy (charge) than a
conventional capacitor and releasing energy (discharge) much faster than a
battery
<= o:p>
T=
he second
category is pseudo-SCs or faradaic SCs, which do not store energy in the do=
uble
dielectric layer. They are like batteries since redox reactions and energy
transfer between electrodes and the electrolyte occur during the charging a=
nd
discharging. This feature provides approximately twice as much higher speci=
fic
energy than EDLCs
<= o:p>
F=
inally,
hybrid SCs are in the third category. These combine the properties of EDLCs=
and
pseudo-supercapacitors through a faradaic reaction at one electrode and an
electrostatic interaction at the other. It is the most modern and advanced
technology, providing higher specific energy (approximately 36 times more t=
han
EDLCs and 18 times more than pseudo-SCs, according to
<= o:p>
A=
mong the
most critical applications of SCs are: load-levelling function; hybridizati=
on
with rechargeable batteries in drive systems and regenerative braking syste=
ms
for partial recharging in electric vehicles; short-term power backup (for s=
afe
shutdown of systems or switching to permanent backup systems); control of
transients or power fluctuations (power smoothing), among others.
<= o:p>
I=
n the
Microgrid Laboratory, a supercapacitor bank comprises ten electric double-l=
ayer
capacitors (EDLC) connected in series of 130 F and 56 VDC each,
BOOSTCAP model BMOD0130, from the USA manufacturer Maxwell Technologies. The
bank’s terminal voltage is 560 VDC, and its total energy stora=
ge
capacity is 0.57 kWh. The power converter connected to this equipment is 30=
kW
rated (Figure 4=
).
<= o:p>
<= o:p>
<= o:p>
Figure 4
Supercapacitors-ESS of the Microgrid
Laboratory: supercapacitor bank (left), a cabinet containing the power
electronic converter (right)
Li-Ion
BESS
L=
ithium-ion
(Li-ion) battery cells consist of a cathode, anode, electrolyte, and separa=
tor
(a safety component that prevents a short circuit between the anode and
cathode, which is permeable to lithium ions). They use non-metallic lithium=
in
the cathode, i.e., chemical compounds called lithium metal oxides capable of
providing lithium ions (Li+), hence their commercial name and their varieti=
es.
The ions are transported through the electrolyte between two electrodes in a
reversible chemical reaction from the cathode to the anode during charge and
discharge
<= o:p>
T=
here are
six commercially available lithium-ion batteries
<= o:p>
A=
ccording
to
<= o:p>
E=
lectrical
energy storage in lithium-ion batteries currently has three main applicatio=
ns
<= o:p>
T=
he
rechargeable lithium-ion battery bank of the Microgrid Laboratory shown in =
 Figure 5 consists of 11 cells of 58.=
36 VDC,
connected in series, model ELPT392- 0002, Samsung brand. The bank’s output
voltage is 642 VDC, with a power of 88 kW and an energy storage
capacity of 44 kWh. The bank is connected to an 80-kW power converter.
Figure 5
Li-Ion BESS from the Microgrid Laboratory=
: cell
bank (left), a cabinet containing the power electronic converter (right)
Vanadium
Redox Flow – BESS
A=
redox
flow battery (RFB) consists of two reservoirs, one with charged electrolyte=
and
the other with discharged electrolyte, an electrochemical energy conversion
system (stacks connected in series or parallel), a hydraulic pumping system=
to
make the electrolyte flow through the conversion system, and the electrical
system for interconnection with the load and the electrical power source
<= o:p>
<= o:p>
<= o:p>
Figure 6
Vanadium Redox Flow - BESS of the Microgr=
id
laboratory: Container housing the vanadium cells (left), double cluster of
power electronic converters (right)
<= o:p>
S=
tandard or
pure flow batteries, among which the vanadium redox flow battery (VRFB) sta=
nds
out, provide the independence or decoupling between storage capacity and po=
wer
as one of the leading technical characteristics
<= o:p>
O=
n the
other hand, hybrid RFB saves at least one solid electroactive material, suc=
h as
the zinc-bromine redox flow batteries (ZBFB), the second most important
technology on the market
<= o:p>
T=
he
Microgrid Laboratory has a VRFB model CELLCUBE FB 20-100 from the Austrian
manufacturer GILDEMEISTER Energy Solutions, with an output power of 20 kW a=
nd
an energy storage capacity of 100 kWh in 12 electrochemical stacks. The bat=
tery
is equipped with two clusters of power converters (3 converters per cluster,
one master, and two slaves) to connect to any of the two three-phase bus ba=
rs
available in the Microgrid Laboratory.
<= o:p>
Meth=
odology:
Design of the laboratory test bench
Figure 7 shows the schematic represe=
ntation
of the test bench set up in the laboratory. All the energy storage agents u=
nder
study will be connected to the main bus bar of the microgrid (B-01), which =
is
connected, in turn, to the main distribution network.
<= o:p>
<= o:p>
Figure 7
One-line
diagram of the test bench
<= o:p>
T=
he ESSs
will all be subjected to the same operating conditions to facilitate a
comparative analysis between the different storage technologies. Due to the
significant amount of energy handled in such tests, both the charge/dischar=
ge
tests and the dynamic tests of active and reactive power set point tracking
will operate one technology at a time. The following is a description of the
test plan to be carried out in this study, which constitutes the methodolog=
ical
basis of this research:
<= o:p>
C=
harge and
discharge tests. Each technology will be subjected to charge and discharge
tests under constant active power conditions. This first experiment aims to
determine the storage capacity and energy backup time provided by each syst=
em
studied. With this information, the round-trip efficiency will be calculate=
d, a
parameter of great importance in ESSs since it quantifies the electrical en=
ergy
that can be extracted from an ESS compared to the amount of electrical ener=
gy
spent in its charging process. In addition, to respect the maximum and mini=
mum
operating limits of all ESS components, it was ensured that the charging and
discharging tests were performed with an SoC between 20 and 80 %.
<= o:p>
A=
ctive and
Reactive Power tracking tests. To evaluate the short-term response in terms=
of
active and reactive power provided by the different ESS technologies under
study, these will be forced to follow the same power time profile in charge=
and
discharge situations. The control of the set point signals applied to the p=
ower
electronic converters (PEC) associated with each ESS will be performed from=
the
laboratory’s Supervisory Control and Data Acquisition (SCADA) system. Thi=
s test
will gauge the efficiency of each ESS technology in tracking the imposed po=
wer
set points in terms of its response time, power tracking error in dynamic a=
nd
steady-state, and the effect of the power tracking on the SoC.
<= o:p>
Charge and discharge tests
This section presents the results obtaine=
d in
the laboratory during the charge and discharge tests of the different ESS
technologies considered. To have comparable cases in the three experiments,
each ESS is subjected to a constant power condition of 10 kW so that the
corresponding SoC varies from 20 to 80% (charging stage) and then from 80 to
20% (discharging stage) in a sustained manner. In Figures 8, 9, and 10, bla=
ck
curves represent the active power at which the ESS is charged/discharged (in
kW), and the blue curve represents the evolution of its state of charge (in=
%).
Tests applied to Supercapacitors-ESS
Figure 8 shows the complete charging and discharging process of the
Supercapacitor-ESS. In this test, the correct operation of the power electr=
onic
converters associated with this technology to track the pre-set active powe=
r is
evident: ±10 kW constant. In its charging stage, the SoC of the
Supercapacitor-ESS goes from 20 to 80%, in a sustained manner, in 72.6 seco=
nds.
This process is associated with an expenditure of 0.202 kWh of electrical
energy from the grid. Once this ESS reaches 80% of the load, the power setp=
oint
applied to the inverter is reversed to start the discharging stage, as show=
n in
the figure. The tests show that going from a state of charge of 80% to 20% =
with
a power of 10 kW takes 67.1 seconds, delivering 0.189 kWh of electrical ene=
rgy.
The findings reveal that, in this type of ESS, to extract 0.189 kWh of
electrical energy, it is necessary to use 0.202 kWh during battery charging.
The ratio between the first and second quantities is called round-trip
efficiency (RTE), which in the case of the Supercapacitor-ESS is 92.4%, an
expected value in terms of efficiency for this technology. An intriguing
observation from the results is that the dynamics presented by the SoC in t=
he
charging and discharging process have a linear nature.
Figure 8
Charge and discharge test performed on the
Supercapacitor-ESS
Tests applied to Li-Ion BESS
The complete charging and discharging pro=
cess
of the Lithium-Ion BESS is shown in Figure 9. It is observed that, in its charging stage, the SoC goes from 20 to
80% in 107.8 minutes, requiring 17.96 kWh of electrical energy. Likewise, in
the previous case, it is observed that once this ESS reached 80% of the loa=
d,
the power setpoint is reversed to start with the discharge process to 20% of
SoC at a constant power of 10 kW. The discharge, on the other hand, lasts 1=
05.2
minutes and delivers 17.54 kWh of electrical energy. In this case, the RTE
efficiency is 97.7%, meaning the electrical energy extracted from this ESS
technology penalizes only 3% of the energy needed to charge the battery. No=
te
that the dynamics adopted by the SoC of this ESS in its charging and
discharging process have a linear characteristic.
Figure 9
Charge
and discharge test applied to Lithium- Ion BESS
Tests applied to Vanadium Redox Flow – =
BESS
The Vanadium Redox Flow-BESS presents a c=
harge
and discharge cycle, as shown in Figure 10. Its charging process (SoC from 20 to 80%) takes about 13.5 hours, =
and
the temporal evolution of the SoC presents a non-linear dynamic. As expecte=
d,
sustaining a charging power of 10 kW for a long time involves an investment=
of
135.3 kWh of electrical energy. This characteristic makes this technology t=
he
one with the highest storage capacity of the three studied here. The results
reveal that this battery can sustain a power supply of 10 kW for at least 7=
.8
hours, representing an energy extraction of 77.8 kWh. It is evident here th=
at,
although this battery provides a reasonably large energy cushion compared to
the previous two, its RTE efficiency is the lowest: 57.5%.
Figure 10
Charge and discharge tests applied to Van=
adium
Redox Flow-BESS
Figure 11 shows the results obtained in this first part of the tests, includi=
ng
the round-trip efficiency calculations for the three ESS technologies studi=
ed.
Figure 11
Round-trip efficiency of the three ESS
technologies studied
Figure 12 (a) shows the charge and discharge cycles of the ESSs studied over =
the
same time scale. In this, the short-term response of the Supercapacitor-ESS
compared to that of the Li-Ion BESS is evidenced, and how, in turn, the time
response of the latter is short if compared to the Vanadium Redox Flow-BESS.
Complementarily, a superposition of the three charging and discharging
characteristics of the ESSs on a logarithmic time scale is given in =
Figure 12 (b).
Figure 12
Comparison of charge and discharge
characteristics of ESSs under constant 10 kW
Finally, for completeness, the tests desc=
ribed
above have been repeated to obtain the charging and discharging characteris=
tics
of the ESSs but for different power values. Table 1 shows the results obtained in the experimental tests. In each case,=
the
round-trip efficiency becomes a characteristic value of each ESS technology=
and
varies very little for each charging and discharging power level. Thus, the
round-trip efficiency of Supercapacitor-ESS is 92%, the Li-Ion BESS is betw=
een
95-97%, and the Vanadium Redox Flow-BESS is 57%.
Table 1
Charge and discharge tests applied to the=
ESS
studied: 20-80-20% SoC-trip
Active and Reactive Power setpoint tracki=
ng
tests
Next, the studied ESSs are subjected to
variable active and reactive power conditions to evaluate their short-term
dynamic response. For this purpose, power profiles have been prepared, taki=
ng
the values 0, 5, 10, and 15 kW (and kVAR) in st=
eps of
20 seconds each. These profiles were loaded into the algorithm commanding t=
he
inverters associated with the ESS in the laboratory’s SCADA.
Figure 13 (a) depicts the response provided by the Supercapacitor-ESS. The gr=
aph
demonstrates the correct performance of this ESS since it successfully reac=
hes
the active power setpoint values in both transient and steady-state regimes.
However, it is worth noting the volatility of the SoC of this technology in
terms of active power injection and absorption requirements. This
characteristic is expected since the Supercapacitor-ESS is the technology w=
ith
the lowest energy storage capacity of the three studied here. In addition,
regarding reactive power tracking (Figure 13 (b)), the Supercapacitor-ESS correctly achieves the setpoints impos=
ed
with a negligible consumption of useful energy (SoC). With these two tests,=
the
usefulness of this ESS in applications requiring fast power response and its
low energy consumption is evident.
Figure 13
|
Power tracking of the
Supercapacitor-ESS |
|
|
|
|
Next, regarding the response presented by=
the
Li- Ion BESS, Figure 14 (a) shows the high effectiveness in active power setpoint tracking =
of
the lithium-ion battery in transient and permanent regimes, shown in Figure 14 (b).
In this test, it is evident that when the=
ESS
is subjected to an active power requirement of short duration, the useful
energy handled is small and almost does not affect the SoC level for the
plotted time scale. A similar situation occurs in the reactive power contro=
l (Figure 14 (b)), in which the reactive power tracking is performed very
efficiently while the SoC does not show an appreciable reduction over time.=
In
this second test, the inverter associated with the ESS presents a correct
performance in short-term power tracking tasks and, in turn, provides opera=
tion
for relatively long times due to its significant energy storage capacity.
Figure 14
Power tracking of the Li-Ion BESS
|
|
|
Finally, Figure 15 shows the performance =
of the
Vanadium Redox Flow-BESS in power-tracking tasks. Figure 15 (a) shows the poor response of this technology in terms of short-te=
rm
active power. On the other hand, when long-term power transitions are requi=
red,
this ESS can respond adequately to such demands (See Figure 10). Finally, regarding reactive power control, Figure 15 (b) shows a null response from the ESS. This is because the actual
prototype in the laboratory does not have the reactive power control enable=
d by
default.
The results presented here offer insights=
into
the advantages and limitations of the three types of ESSs examined in terms=
of
their required time response. In addition, they confirm the different
applications of such technologies in their interaction with the electric po=
wer
system, as discussed in section 2 of this paper.
Figure 15
|
Power tracking of the Vana=
dium
Redox Flow-BESS |
|
|
|
|
I=
n this
study, a comprehensive study has been carried out to obtain the dynamic
responses of three ESS technologies: supercapacitors, lithium-ion batteries,
and Vanadium redox flow batteries. The work has been done on actual commerc=
ial
models with industrial characteristics available in the Microgrid Laborator=
y of
Universidad de Cuenca. In align with the research objectives aimed at
evaluating the performance of energy storage systems in terms of their
efficiency and dynamics of active and reactive power for applications in po=
wer
systems, two tests were devised: 1) charge and discharge and 2) active and
reactive power set point tracking. The most relevant results are presented
below:
<= o:p>
S=
upercapacitor-ESS:
the results of charge and discharge tests showed that this energy storage
medium has the lowest storage capacity: 1/90 of the capacity of Li-Ion BESS=
and
1/670 of the capacity of Vanadium Redox Flow-BESS but with very high current
density since it allows swift responses in terms of active and reactive pow=
er
with practically imperceptible error margins. From these tests, it is concl=
uded
that this ESS is ideal for applications whose power demands have a very
short-term variability, such as power smoothing, frequency and voltage cont=
rol
in electrical systems, and voltage dips suppressor when switching from a
primary supply source to a backup source during a contingency. Its round-tr=
ip
efficiency is around 92%.
<= o:p>
L=
i-Ion
BESS: Tests performed on this commercial model showed that its storage capa=
city
allows it to sustain significant power for at least a few hours, which, add=
ed
to its high current density, allows practically instantaneous transitions of
active and reactive power, allowing this ESS technology to be implemented in
applications similar to that of Supercapacitor-ESS. In addition, its long
autonomy allows it to be used as a backup system when the primary energy su=
pply
is lost in an electrical installation, widening the range of applications
concerning the previous technology. Experimental results showed this techno=
logy
has a 95-97% round-trip efficiency.
<= o:p>
V=
anadium
Redox Flow BESS: after conducting charge and discharge tests on this type of
battery, it was found to have the highest capacity of the three ESSs studie=
d.
This technology enables the sustenance of significant power load requiremen=
ts
during tens of hours of uninterrupted operation. From the experimental resu=
lts,
it is concluded that this ESS is ideal to be implemented as a reliable and
long-duration power backup system in applications where the primary supply
source presents a high risk of unavailability or in base load applications.
However, this ESS is unsuitable for applications where high-speed tracking =
of
load power is required due to the electrochemical constraints of the tested
commercial model. The round-trip efficiency is around 57%, the lowest of the
three technologies studied.
<= o:p>
I=
n addition
to the conclusions presented here, the results of this study provide charge=
and
discharge charts of the different ESSs and values of charge and discharge t=
imes
at different power levels. These data enable the elaboration of characteris=
tic
power vs. charging time curves, which help feed mathematical ESS models.
Integrating mathematical ESS models in the grid studies facilitates obtaini=
ng
numerical results that closely resemble the actual operation of these
prototypes, thereby enhancing accuracy when sizing the energy storage
facilities for various applications within the electrical power system
framework.
<= o:p>
Acknowledgmen=
ts
T=
he authors
thank Universidad de Cuenca for easing access to the facilities of the
Microgrid Laboratory of the Centro CientÃfico =
Tecnológico y de Investigación=
Balzay (CCTI-B), for allowing the use of its equipmen=
t, and
for authorizing its staff the provision of technical support necessary to c=
arry
out the experiments described in this article.
<= o:p>
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Comparative study of dyna=
mic
response by three types of energy storage systems for grid studies: A
Microgrid Laboratory experimental-based study 5