[IEEE 2019 Innovations in Power and Advanced Computing Technologies (i-PACT) - Vellore, India (2019 3 22-2019 3 23)] 2019 Innovations in Power and Advanced Computing Technologies (i-PACT) - A Review o

Prévia do material em texto

2019 Innovations in Power and Advanced Computing Technologies (i-PACT)
A Review on Microgrids with Distributed Energy
Resources
G V Brahmendra Kumar∗
Student Member, IEEE
School of Electrical Engineering
VIT University, Vellore, India
brahmendrakumar.g@gmail.com
Palanisamy K
Member, IEEE
School of Electrical Engineering
VIT University, Vellore, India
kpalanisamy@vit.ac.in
Abstract—In association with increasing in penetration of
distributed generation sources (DGs) into power systems, and
their power management of different DGs and the grid has
elevated as a major concern. Though, Microgrid (MG) is the
extensively an accepted concept for the association of DGs in
power system networks. Integrating renewable energy sources
(RESs), which are often connected via power electronic interfaces
into the power grid, can sometimes be a stimulating task just from
a purely technical point of view. Thus, the MG is a promising
option for future power system interfaces. Evolving the challenges
has taken place in terms of the power system control, power
quality improvement, reliability, and energy management. The
MG operational performance, stability, basic control issues and,
concept of MGs are presented in this paper.
Index Terms—Microgrids, distributed energy resources, bat-
tery, supercapacitor, hybrid energy storage system (HESS), DC-
DC converter, DC microgrid, AC microgrid, hybrid microgrid.
I. INTRODUCTION
In day to day process, the utilization of distributed energy
resources (DERs) is increasing. The MG is a common system
for connecting the number of DG sources. The DERs, energy
storage systems (ESSs) and loads are connected together to
form a MG. Though, the DGs can bring challenges to the
distribution system such as power balance, frequency and
voltage variations, etc. Earlier days the only load is taken into
account on a distribution power system. Now, the presence of
generation and storage systems in MG are altering the reg-
ulatory and operational arrangement of the traditional power
system. Thus, the MG can solve the issues caused by the DG
units and creates the large-scale appliance for DGs feasible.
MGs are primarily classified as AC, DC and hybrid MGs.
The AC and DC MGs are associated together to form a
hybrid MG [1]. The DC MG performs better over the AC
MGs. In DC MG, the power balance is maintained at DC
link by controlling the DC link voltage. But, the AC MG
control also includes maintaining voltage, frequency within
limits such that synchronization is maintained with the grid.
The DC MG preferred for the better efficacy, stability, less
complexity design, and low power losses [2].
Fig. 1 shows a typical DC coupled MG system. It comprises
several DGs and ESS elements, and these are connected to a
collective DC link. The DGs and ESSs are connected using
DC link by interfacing converters. The ESSs are typically a
battery, supercapacitor, fuel cell and compressed air storage,
etc.
Fig. 1. Typical DC coupled microgrid system.
In this, the ESS can supply the power to meet the demand.
Hence, the power balance can achieve by the ESS in this
system, and it is in MG able to perform highly reliable, stable
and self-balancing power supply. Thus, the ESS is the essential
component in the integration of DG into the MG. The power
balance is achieved by the following equation,
PIN = PDC + POUT (1)
Where, PIN = PRES+PESS and POUT = PDCL, PRES is
the power from the renewable systems, PDC power supplied
by DC the link capacitor and PESS is the power from storage
devices. However, the PIN is equal to POUT , the PDC will be
zero. Whenever there is an unbalance among input and output,
the DC link capacitor starts charging or discharging thereby
increasing or decreasing in DC link voltage correspondingly
[2].
The structure of an AC coupled MG system is shown
in Fig. 2. The DGs and ESSs are associated to common
AC link through interfacing converters. The ESSs require
the bidirectional converters to deliver the bidirectional power
supply. This system is generally used to supply grid level AC
voltages directly/indirectly by interfacing converters during
dominant generation sources in the MG. The AC bus volt-
age/frequency control and power balance have achieved by
1978-1-5386-8190-9/19/$31.00 ©2019 IEEE
2019 Innovations in Power and Advanced Computing Technologies (i-PACT)
this power management strategy. The power balance in the
system is taken by following equation,
PESS = PGRID − PRES (2)
In some AC MGs to reduce the number of transformation
stages can be switched by multi-port converters, which connect
different power sources into a single power converter. Hence,
Fig. 2. Typical AC coupled microgrid system.
such a system viewed as multiple interfacing ports with a
single power processing platform. The input power sources are
basically interlinked to high-frequency AC bus, and isolated
transformer in addition to AC/DC/AC interfacing converters
are used to associate the generation into the grid [1].
Fig. 3 shows the AC-DC coupled hybrid MG system. In
this, the both AC and DC links have DGs and ESSs, and
these are connected by interlinking converters (ILCs). This
system needs more synchronization for voltage and power
limitation among AC and DC systems, which enhances the
system reliability and capacity. Such a system has improved
the overall system efficacy, minimizes the system cost, and
reduces the conversion stages between AC and DC links. Thus,
the AC-DC coupled hybrid MG is the most assuring choice
in the near prospect [1]. The power balance can be obtained
from the following equation,
PRES + PESS + PGRID + PLOAD = Peff (3)
Where PRES , PESS , and PGRID are the RESs, ESSs,
and utility grid powers, respectively. The power PLOAD =
PDCL+PACL is the combination of both DC and AC load
powers and Peff is the effective power flow from different
sources such as RES, ESS, and utility grid to sustain the power
balance at the DC link [1].
This structure is employed two methods to control the
voltage and dispatched power. In first, coordination between
DGs-ESSs on AC and DC links is essential to deliver the
dispatched output powers and, the ILC acts as a DC link
voltage regulator mode to control the DC voltage. In second,
ILC and DGs-ESSs on AC link concurrently allowed the
dispatched power and the DC link voltage is governed by
the DGs and ESSs on DC bus in the grid-connected mode of
control. Although in an islanded control mode, coordination
Fig. 3. Typical AC-DC coupled microgrid system.
amongst ILC, DGs-ESSs on AC and DC bus is necessary to
monitor DC link voltage, AC link Voltage, and frequency, and
stabilize the MG whole generation and demand abilities at the
same interval.
This paper is organized as follows. In section II a brief
description of MG controls and management systems is ex-
plained and Section III presents the MG control techniques.
Section IV is the conclusion.
II. BRIEF DESCRIPTION
A 1-Phase grid interactive voltage source converter
(GIV SC) with energy management is proposed in [3]. The
DC voltage restoration and power quality are the signifi-
cant factors that regulate the performance of grid-integrated
system [4]. In this system achieves the main principle of
real power shift along supporting services like reduction of
current harmonics, reactive power assistance and power factor
improvement at the point of common coupling (PCC). The
battery and Supercapacitor are used for maintaining the power
balance in the MG. These controls to sustain the sudden
changes in power flows, which results in fast restoration of
DC link voltage, reduction of current stress on the battery and
obtained the effective management strategy. The bidirectional
buck-boost DC-DC converter topologies are employed in the
scheme, which can be used to regulate the power flow among
the batteries, supercapacitor and utility grid. GIV SC is used
to interface the HESS to utility grid. A unified current mode
control for hybrid vehicles and as pulsed load controllers have
the drawbacks of compensatordevice and lowering the efficacy
at light load circumstances. The DC link voltage regulator is
an optimal solution for the transient periods causes: 1) sudden
changes in the renewable source at DC link; 2) variation in
instantaneous power towards the AC side. To overcome those
problems with a fast-acting DC link voltage based energy
management method has employed in these approaches [3]
[4].
In [5], presents the composite energy storage system
(CESS) using modular interleaved bidirectional dual active
bridge (DAB) converter for interfacing battery and superca-
pacitor to the DC link. CESS requires high energy and power
2
2019 Innovations in Power and Advanced Computing Technologies (i-PACT)
density devices. The higher range power devices are com-
pressed air storage and pumped hydro storage, etc. Conversely,
MGs power stages are in the capacity of few megawatts.
Hence, the intermittent characteristics of RESs and continuous
changes of load; the battery, supercapacitor, flywheel are
usually required in a renewable powered MG. But, for high
energy and power requirements to meet through the battery
and supercapacitor are the promising option to the CESS
system and, such a system increases the lifetime of the battery.
The DAB performs the soft switching and, the high-frequency
switching operation can be obtained even at higher energy
levels. Thus, the capacity of the capacitor bank can be reduced.
However, the flexible power distribution within the battery and
supercapacitor can be achieved by DC-DC topology with its
energy management system [5].
Power management strategy of different ESSs for MG is
presented in this [6]. This method is proficient through taking
an offset voltage. The offset voltage is regulated with the
state of charge (SOC) error between powers supplied by
the batteries. Thus, the batteries to reach discharge limits
together and, their energy can be fully consumed. The bat-
tery with higher SOC, the dynamic power control assigns
the power requirement for transient between the battery and
supercapacitor. Using this system, the battery can perform the
continuous power application and the supercapacitor engrosses
only short-term power requirement. Thus, the battery neglects
the redundant charging and discharging currents, and then
extends the battery lifetime, while supercapacitor size can be
decreased [6].
The oscillations in the battery current and energy loss are the
important factors in HESS. The energy loss is due to the inher-
ent resistance of the supercapacitor, which can be minimized
with the purpose of enlarges the battery discharge duration.
These issues can be minimized in [7] using multiplicative-
increase-additive-decrease (MIAD) principle. This control is
the optimal solution for the above problem statement and, also
energy supply in the HESS can be regulated. This method is
suitable for electric power vehicles or home energy systems,
where longer lifetime and shorter size of the battery have been
required [7].
The state-space averaged model is a newly developed area
to control the design issues in power system determined by
HESSs [8]. In this, presents to obtain the robust tracking of
the battery current, and the load voltage variables, the other
one is to attain steady evolution of those variables for the
period of load switch. The bidirectional buck-boost converters
are actively controlled the battery and supercapacitor currents.
Hence, this control helps to preserve the battery and to improve
the entire system working performance. This method will
obtain feasible appliances in photovoltaic (PV) and wind
systems, plug-in hybrid electric vehicles, and MGs [8].
MGs are fascinating significant attention meanwhile they
can remove the stress of main transmission systems, mitigate
the feeder losses, and increase the power quality of the
system. This is possible with power sharing method presented
in [9]. In this, explains the overview of different active
and reactive power-sharing methods. In spite of, the poor
active and reactive power issues are caused by the mismatch
impedance in distribution generation feeders. Likewise, un-
balanced/nonlinear loads are exhibited and, which can affect
the reactive power supply. To overcome these problems, the
adaptive droop control and virtual impedance methods are
implemented. Therefore, improved droop control, network-
based control, and cost-based droop techniques are imple-
mented and compared for active power supply [9]. Thus, the
hierarchical control strategies are employed as an addition
to these methods. A complete analysis and performance of
the advanced control methods for active and reactive power
sharing have been presented in [9].
According to MG operating conditions, P/f operating
curves are performing the local voltage and power control
loops at each battery and PV units. The control tactics are
evolved to coordinate each unit of the performance of the
operating system. The process of the system is to sustain
balance among generation and consumption, whereas ensuring
controlled charging/discharging of batteries in the MG. There-
fore, specially implemented multi-segment power/frequency
(P/f ) characteristics curves are configured in this, [10]. These
characteristics present a better performance in MG operating
conditions and without any delay in the external communica-
tion process and management systems. Thus, the system is to
control based on the available power in the PV system and
SOC of batteries and load demand in the MG. This strategy is
implemented based on the multi-loop controllers. However,
the system is better performance owing to a battery and
multiple PV based on the decentralized power management
methodology [10].
Hybrid AC/DC MG places a predominant role in the MG
operating system. Proper control and power management strat-
egy are required for these MGs. In [11], enables a flexible
operation with an interlinking AC/DC converter (IC) control
scheme during different operating modes. This power manage-
ment strategy provides the power reference for IC control to
share the power demand between the existing power sources in
both AC and DC MGs. While, IC acts as a supplier for one MG
and, also serves to be a load to other MGs. To share the power
requirement between existing sources by the measuring of
AC MG frequency, DC MG voltage, and employing proposed
droop characteristic in [11]. Using this method, IC can share
the power in both microgrids during an islanding conditions
as well as the switch from grid-connected to an islanded mode
of operations. Thus, the requisite power conversion stages
and system cost have been reduced by using this system.
The Hybrid AC/DC MG system different operation modes
and control methods in steady and transient state conditions
have been given in [1]. The control methods for different
structure systems shown as AC coupled, DC coupled, and
AC-DC coupled hybrid MGs. The main concerns for these
MGs consist of frequency and voltage control, and real-time
power transfer between the sources in MGs. The short duration
power management is a more significant factor to regulate
and interface of power converters in the MG. However, the
3
2019 Innovations in Power and Advanced Computing Technologies (i-PACT)
solutions for above issues have been illustrated by the power
management strategies presented in [1].
In [12], proposed a centralized control design for a small-
scale MG. This method performs the following functions:
generation of active power and load shedding acts as avoiding
the overcharge and deep discharge in storage systems and to
evading the intermittent degradation conditions for restoring
the SoC in storage systems. Using this scheme, the different
capacity of storage elements are performed uniform charge/
discharge ratios. The ESS has sized optimally to eliminate
intermittent disturbances in the storage systems and balanced
the SOCs. The stable and reliable performance of the system
has achieved by this approach.
A MG plays a fundamental part in the transformationexisting generation electricity grid to the smart grid in future.
In [13], proposed a mixed-integer-linear-program (MILP )
optimization scheme for renewable energy generation and
future electricity usage. The objectives of this approach are
to meet the demand of the supply and load smoothing. In
order to perform a smooth performance of the system by a
smooth switching droop control (SSDC), [14]. The SSDC
is an aid to RES/ESS system to coordinate the performance
in MGs. Thus, the proposed scheme is to validate the flexible
operation of the system and, automatic power sharing among
the parallel units in voltage control mode. The performance of
this system results is achieved by real-time hardware-in-the-
loop (HIL) under different scenarios.
In [15], proposed the hierarchical control technique for DC
MG groups. Adaptive droop control (ADC) is used to improve
the efficacy of parallel batteries in MG systems. The current
distribution within the sources in MG and DC-bus voltage is
regulated in the primary level of operation. In the secondary
level, the power flow control can be achieved. Here, a dis-
tributed power flow controller is implemented to regulate the
power supply among the MGs corresponding to their confined
SoCs automatically. Thus, the equal SoCs are presented in the
different amount of loads. The proposed approached is tested
by the HIL simulation studies. The SoC-based ADC system
is balanced the SoC in each ESS, and also ESS with higher
SoC can deliver more power, although other with lesser SoC
can supply lower power. Thus, the SoC change between each
ESS has gradually reduced and, the load power supply can
be shared equally among all the distributed energy storage
units (ESUs). The droop factor is inversely proportional to the
nth order of SoC. Therefore, the change between SoC makes
smaller, and the power output from converters come to be
equal. By varying the exponent n of SoC, then the power-
sharing speed can be actively controlled. Though, the equally
power-sharing and SoC balancing of distributed ESS in DC
MGs have been implemented in this scheme [16].
The MG is an independent network; it can alter the oper-
ation modes among islanded and grid-connected systems. In
[17], implemented the droop-based demand response (DB −
DR) approach works on islanded as well as grid-connected
modes. This control can maintain the stability of supply and
demand of MG systems without any exchanges in system.
The required amount of supply can produce the proper voltage
at the load coupling point in the MG. The frequency of this
voltage is concluded by the effectively designed droop based
control, though demand power dissipation is automatically
altered based on MG process condition.
The frequency and voltage control actively participate in
microgrids. In [18], MG central controller (MGCC) has
implemented to restore the voltage and frequency, which is
related to the secondary control in droop-controlled micro-
grids. The proposed scheme does not only control the voltage
and frequency but also assure the sharing of reactive power.
The main aspect is the failure of the single system during
the faults; the entire system will not be failed down. In
[19], proposed a distributed control system based on DC bus
signaling (DBS) for PV with battery-based ESS. In this, the
battery, PV, and grid-connected converters are implemented.
In grid-connected PV sources, particularly in the state of
mismatching conditions, the performance of the battery unit
is effectively utilized. This approach can accomplish flexible
power sharing among the different distribution converters, and
the battery is operated within the SoC limits.
The power management methodology of the PV/battery
hybrid system is proposed in [20]. In this, the PV/battery can
supply the maximum power to the MG provided that there is
sufficient load demand in the MG . Whenever the PV power
is more, the excess power will be saved in the battery unit.
Although the PV power is lower, the battery can deliver the
demanded amount of supply to meet the load. This scheme is
done by using the multi-loop controller without depending on
any communications. Thus, the hybrid system is able to supply
the maximum power as long as there is a required load. Unless
the hybrid unit will autonomously follow the changing load
while storing the excess energy in the battery. The total power
is regulated through maximum PV power extract at that instant
and battery SOC.
The presence of ESS serves the maintain stability dur-
ing generation and load shortcomings, increasing the power
quality, aids the integration of RESs and, providing ancillary
services. The ESS in the MG, the sizing is the significant
factor and, cost to connect equipment to the distribution
system. In [2], proposed the energy storage minimization
for battery-based equipment by using ramp-rate control. This
system is shown, develops the reliability of supply, reduces the
ESS sizing and maintains the power balance as considerably.
Here, the HESS can operate during transient power variations,
overcome the current stress in batteries and enhances the
battery life-cycle. This strategy is used to achieve the required
power and the minimum energy storage desires respectively.
The DG source can concede the other significant socio-
economic benefits. In [21], proposed the multi-objective op-
timization model, which is used for the storage dispatch in
a grid-connected MG with ESS and RES assets. In this,
presents the electricity cost reduction of generated sources in
MG based on the multi-objective optimization is converted
to single objective optimization. The supply cost and utility
objectives in a MG are relevant to the peak demand and
4
2019 Innovations in Power and Advanced Computing Technologies (i-PACT)
load smoothing. In order to coincide the demand and load
smoothing are possible with the ESS operation in the MG.
Hence, coordinated optimization support dispatch of ESS
might permit MGs to group their RES and ESS in the sequence
of lessens their net supply cost, compared to grid associated
with independently.
The novel coordinated frequency control (CFC) approach
is presented in [22]. This scheme presents the fast responding
of the PV systems, battery-based systems and thermostatically
controlled loads (TCLs) as well as slow responding of diesel
generator system. The purpose of this system is to control
the frequency by adopting the fast responding of the device
in the transient state and, return back to normal operating
circumstances in a steady state. During the regular operating
situations, the PV and ESS systems have restored the power by
changing a load of diesel system without any interlink device.
Hence, the PV system is slowly reversed back to the restrained
PV power period to MPPT after over-frequency regulation.
Moreover, the TCLs are not only regulating the frequency but
also thermal unit support which perspective of the customers.
Thus, the effective and stable frequency regulation system is
achieved by this strategy.
Based on the preceding issues the MG is developed to
achieve the continuous supply and cost-effective objectives.
The scheduling process in the MG is accomplished by an en-
ergy management practice, which can operate lower bandwidth
than power and control management levels. Thus, the MG
system has a considerably inferior influence on stability and
robustness achievement. The control and management proce-
dures may affect the instant provisions related to frequency,
voltage, current regulations, and power quality. Therefore, the
adaptable online microgrid-energy management system (MG-
EMS) has proposed in [23]. This scheme achieves the proper
integration and communication among modules as well as the
controlled interface. It performs the function in MG systems
for forecasting, scheduling, acquisition data, and processing
respectively. The system deals with the variability presented
by the renewable generator. The scheduling process relies
upon the economic management for islandedor grid-connected
operations. The processing module is according to the result of
the forecasting module in order to perform limited prediction-
error in the system. This system has to generate associating
commands for DERs controllers to obtain the entire system
optimally, which is not only considerably current MG perfor-
mance, but also including technical, economic, environmental
limitations and external compliance. Thus, this system is an
ability to work under several modes of operation in MG and,
conquered the operating cost.
In the context of MG system failure and low power
consumption cases, to manage and monitor these problems
by advanced power line communication (PLC) technology
presented in [24]. In this system, there is no requirement
for any power amplifier to include the signal in power lines.
Nevertheless, the communication signals are generated by the
switching frequency modulation. In any case, a low power
signal is presented at that instant a small duty cycle pertur-
bation switching frequency is appended to the response of
the transmitted signal. In this, the converters are performed in
three different switching frequency states as distinguishing the
switching signal on bus voltage. The PLC method is employ-
ing with digitally controlled DC-DC converters. Hence, the
converter control including integrates communication network
demonstrates the stable operation. The interface set-up is being
used to engage utility necessities for DERs.
The current optimization techniques are well performed to
improve efficacy, distribution, and resiliency in MG EMSs.
The extreme difficulties in a MG are protection and control.
However, these controllers can solve the several problems
occurred in the MG operations being distributed energy from
DGs-ESSs.
III. CONTROL TECHNIQUES IN MICROGRIDS
In earlier days, the integration of RESs with the grid is
a difficult task and also to concede the demand requirement
for clean and reliable electricity supply generation. In these
days, several controllers have been improved to solve the
critical issues present in the MG. To control and improve the
performance of the MG system various controllers are imple-
mented in [1] - [24]. In this paper, the following controllers
are presented here for maintaining the proper active, reactive
power quality, accurate power management and, control the
effects on the system operates in the various modes in the
MG unit.
• Grid-interactive converter control [3] [4]
• Phase-shift controlled DAB converter [5]
• Multiplicative-increase-additive-decrease method [7]
• Cooperative distributed control [9]
• Adaptive virtual impedance controller [9]
• Non-linear cost based droop scheme [9]
• Linear cost function scheme [9]
• Network based power sharing scheme [9]
• Particle swarm optimization (PSO) technique [9]
• Droop based power sharing control schemes [10] [11] [14]
◦ P − V/Q− f droop control
◦ Adaptive voltage droop control method
◦ Optimised droop control
◦ A common variable based power sharing scheme
◦ Smooth switching droop control (SSDC)
• Hierarchical controller MGs [15]
◦ Primary control
◦ Secondary control
◦ Tertiary optimal control
◦ Predictive control
◦ Improved algorithm based on graph theory
◦ Improved algorithm based on multi-agent system
◦ Gain-scheduling method
• MG central controller [18]
• Distribute control system based on DBS [19]
• Multi-loop control [20]
• Multi-segment adaptive droop control [20]
• Novel coordinated frequency control [22]
5
2019 Innovations in Power and Advanced Computing Technologies (i-PACT)
In general, the MG and integration DERs perform the
several tasks to address towards an implement system for
protecting and control such that present levels of safety are not
significantly altered and potential concerts of DGs are fully
equipped. Though, the MG unit is ultimately presented the
centralized or decentralized controls. The centralized control
can share the huge information transmittance within involving
units and conclusion is given at a single point. Furthermore,
in decentralized control every system is governed by a local
controller without associating the condition of another system.
An understanding of certain two important control designs can
be attained by implies of hierarchical control methods.
IV. CONCLUSION
This paper presents the MGs operational performances, their
control schemes and issues respectively. In the operation of
MGs, the power management and control approaches are the
highly prominent considerations. Thus, the control approaches
and power management strategies of various types of MGs
under various operating situations are presented in this paper.
The MG is connected to several DGs to operate in various
control modes depending on the performance of the MG.
It requisites at least one ESS and also includes the RES
production. However, the ESS in MG realizes the proper sizing
and SoC balancing needs the further optimization techniques
have provided in future work. The future trends in MG study
are to examine full-scale deployment, field demonstration,
and test performance assessment of frequency and voltage
control schemes supporting several working provisions. The
transition between grid-connected and an islanded modes on
communication aspects between DG and long perception of
distributed production. In the future, the MG transformation
becomes into the smart, robust energy transfer system by
contributing reliability and security interests. Finally con-
cluded that smart grids are being technologically advanced as
the subsequent generation of power systems. The smart grid
contains the interconnected MGs, specifically at distribution
levels wherever the DGs are progressively more used.
REFERENCES
[1] F. Nejabatkhah and Y. W. Li, “Overview of power management strategies
of hybrid ac/dc microgrid,” IEEE Transactions on Power Electronics,
vol. 30, no. 12, pp. 7072–7089, Dec 2015.
[2] V. B. K. Gundumalla and S. Eswararao, “Ramp rate control strategy for
an islanded dc microgrid with hybrid energy storage system,” in 2018
4th International Conference on Electrical Energy Systems (ICEES), Feb
2018, pp. 82–87.
[3] T. N. Reddy, M. K. Mishra, and S. Srinivas, “Grid interactive combined
supercapacitor/battery energy storage system with power quality fea-
tures,” in 2015 IEEE International Conference on Industrial Technology
(ICIT), March 2015, pp. 2600–2605.
[4] N. R. Tummuru, M. K. Mishra, and S. Srinivas, “Dynamic energy
management of renewable grid integrated hybrid energy storage system,”
IEEE Transactions on Industrial Electronics, vol. 62, no. 12, pp. 7728–
7737, Dec 2015.
[5] H. Zhou, T. Bhattacharya, D. Tran, T. S. T. Siew, and A. M. Khambad-
kone, “Composite energy storage system involving battery and ultraca-
pacitor with dynamic energy management in microgrid applications,”
IEEE Transactions on Power Electronics, vol. 26, no. 3, pp. 923–930,
March 2011.
[6] H. Kim, C. Y. Chun, K. Lee, P. Jang, and B. Cho, “Control strategy
of multiple energy storages system for dc microgrid,” in 2015 9th
International Conference on Power Electronics and ECCE Asia (ICPE-
ECCE Asia), June 2015, pp. 1750–1755.
[7] M. Choi, S. Kim, and S. Seo, “Energy management optimization in a
battery/supercapacitor hybrid energy storage system,” IEEE Transactions
on Smart Grid, vol. 3, no. 1, pp. 463–472, March 2012.
[8] T. H. Hoeguk jung, Haifeng Wang, “Control design for robust tracking
and smooth transition in power systems with battery/supercapacitor
hybrid energy storage devices,” Journal of Power Sources, vol. 267,
pp. 566–575, December 2014.
[9] Y. Han, H. Li, P. Shen, E. A. A. Coelho, and J. M. Guerrero, “Review
of active and reactive power sharing strategies in hierarchical controlled
microgrids,” IEEE Transactions on Power Electronics, vol. 32, no. 3,
pp. 2427–2451, March 2017.
[10] H. Mahmood and J. Jiang, “Decentralized power management of mul-
tiple pv, battery, and droop units in an islanded microgrid,” IEEE
Transactions on Smart Grid, pp. 1–1, 2018.
[11] N. Eghtedarpourand E. Farjah, “Power control and management in a
hybrid ac/dc microgrid,” IEEE Transactions on Smart Grid, vol. 5, no. 3,
pp. 1494–1505, May 2014.
[12] N. L. Daz, A. C. Luna, J. C. Vasquez, and J. M. Guerrero, “Centralized
control architecture for coordination of distributed renewable generation
and energy storage in islanded ac microgrids,” IEEE Transactions on
Power Electronics, vol. 32, no. 7, pp. 5202–5213, July 2017.
[13] P. Malysz, S. Sirouspour, and A. Emadi, “An optimal energy storage
control strategy for grid-connected microgrids,” IEEE Transactions on
Smart Grid, vol. 5, no. 4, pp. 1785–1796, July 2014.
[14] D. Wu, F. Tang, T. Dragicevic, J. C. Vasquez, and J. M. Guerrero, “A
control architecture to coordinate renewable energy sources and energy
storage systems in islanded microgrids,” IEEE Transactions on Smart
Grid, vol. 6, no. 3, pp. 1156–1166, May 2015.
[15] Q. Shafiee, T. Dragievi, J. C. Vasquez, and J. M. Guerrero, “Hierarchical
control for multiple dc-microgrids clusters,” IEEE Transactions on
Energy Conversion, vol. 29, no. 4, pp. 922–933, Dec 2014.
[16] X. Lu, K. Sun, J. M. Guerrero, J. C. Vasquez, and L. Huang, “State-
of-charge balance using adaptive droop control for distributed energy
storage systems in dc microgrid applications,” IEEE Transactions on
Industrial Electronics, vol. 61, no. 6, pp. 2804–2815, June 2014.
[17] A. Elrayyah, F. Cingoz, and Y. Sozer, “Smart loads management using
droop-based control in integrated microgrid systems,” IEEE Journal of
Emerging and Selected Topics in Power Electronics, vol. 5, no. 3, pp.
1142–1153, Sep. 2017.
[18] Q. Shafiee, J. M. Guerrero, and J. C. Vasquez, “Distributed secondary
control for islanded microgridsa novel approach,” IEEE Transactions on
Power Electronics, vol. 29, no. 2, pp. 1018–1031, Feb 2014.
[19] K. Sun, L. Zhang, Y. Xing, and J. M. Guerrero, “A distributed control
strategy based on dc bus signaling for modular photovoltaic generation
systems with battery energy storage,” IEEE Transactions on Power
Electronics, vol. 26, no. 10, pp. 3032–3045, Oct 2011.
[20] H. Mahmood, D. Michaelson, and J. Jiang, “A power management
strategy for pv/battery hybrid systems in islanded microgrids,” IEEE
Journal of Emerging and Selected Topics in Power Electronics, vol. 2,
no. 4, pp. 870–882, Dec 2014.
[21] M. R. Sandgani and S. Sirouspour, “Coordinated optimal dispatch
of energy storage in a network of grid-connected microgrids,” IEEE
Transactions on Sustainable Energy, vol. 8, no. 3, pp. 1166–1176, July
2017.
[22] S. Acharya, M. S. E. Moursi, and A. Al-Hinai, “Coordinated frequency
control strategy for an islanded microgrid with demand side management
capability,” IEEE Transactions on Energy Conversion, vol. 33, no. 2, pp.
639–651, June 2018.
[23] A. C. Luna, L. Meng, N. L. Diaz, M. Graells, J. C. Vasquez, and
J. M. Guerrero, “Online energy management systems for microgrids:
Experimental validation and assessment framework,” IEEE Transactions
on Power Electronics, vol. 33, no. 3, pp. 2201–2215, March 2018.
[24] W. Stefanutti, S. Saggini, P. Mattavelli, and M. Ghioni, “Power line
communication in digitally controlled dcdc converters using switching
frequency modulation,” IEEE Transactions on Industrial Electronics,
vol. 55, no. 4, pp. 1509–1518, April 2008.
6