WK,QWHUQDWLRQDO&RQIHUHQFHRQ5HQHZDEOH(QHUJ\5HVHDUFKDQG$SSOLFDWLRQV 1RY%LUPLQJKDP8.

Power Management of Grid Connected Hybrid

Microgrid with Dual Voltage Source Inverter
Ram Shankar Yallamilli Mahesh K. Mishra
Student Member, IEEE Senior Member, IEEE
Department of Electrical Engineering Department of Electrical Engineering
Indian Institute of Technology Madras Indian Institute of Technology Madras
Chennai, India Chennai, India

Abstract—This paper proposes a grid connected hybrid mi- storage system. [3], [4] is considered in this work, where
crogrid system with dual voltage source inverter (DVSI) using supercapacitor absorbs the sudden transients and oscillations
modified instantaneous symmetrical component theory (MICST) thereby increasing battery performance and life span.
for power sharing among inverters. In this paper a reduced
DC link voltage has been achieved, efficient, simple power On the other hand energy management system (EMS) [5],
management algorithm (PMA) is proposed and new method [6] is necessary for the control and power management in mi-
is introduced for DVSI control parameter extraction which crogrid, it is responsible to manage energy efficiently between
reduces control complexity and overall system cost. The Proposed various sources and loads. EMS proposed in this work makes
topology consists of a three phase dual voltage source inverter use of simple power management algorithm (PMA) offering
(DVSI) which transfers the active power between grid and
microgrid based on renewable power availability and state of several advantages like (1) fast and better regulation of DC
charge (SOC) limits of hybrid energy storage system (HESS). link voltage, (2) effective energy management, (3) eliminates
Besides, offering ancillary services such as harmonic mitigation, current stresses on battery and (4) power quality improvement
reactive power support and unity power factor at the point of at PCC.
common coupling (PCC). The proposed system is tested and In a microgrid power from various renewable energy sources
validated using MATLAB based simulink environment.
is interfaced to grid and load using power electronic converters
Index Terms—Battery, supercapacitor, power quality, dual
called as grid tied inverters (GTIs), which play an important
voltage source inverter, state of charge, control parameters.
role in transferring power among microgrid, main grid and
loads. However the use of grid tied inverters for high power
I. I NTRODUCTION
applications is limited by the current rating of semiconductor
The ever increasing demand for energy and depletion of devices used. Hence parallel operation of grid tied inverters
fossil fuels make people to switch for renewable technologies is suggested in contrast to the use of centralised grid tied
like PV, wind etc. Moreover, the levelised cost [1] of renew- inverters [7] for high power requirements in this work. More-
able power generation technologies is decreasing day by day over, in the parallel inverter scheme as the total load power is
which makes it a feasible option. Renewable energy based shared among inverters hence the power loss across switches
distributed generation technologies are penetrating more in to decreases there by improving the reliability when compared
the power system thus forming smart grids which comprises to centralised single inverter.
of interconnected microgrids at distribution level. Microgrids Power quality is one of the important aspects in microgrid.
can come up with the use of AC or DC voltages in the local But, due to the increased proliferation of power electronic and
grid thus hybrid AC/DC microgrids are often implemented and unbalanced electrical loads, power quality in power distribu-
have the advantages of both AC/DC power systems, so they tion systems is degraded. Moreover, industrial automation is
are considered as a bridge to future energy distributed systems. very sophisticated now a days, which requires clean power.
called as Hybrid AC/DC Microgrids [2], which are further Hence it is necessary to compensate non-linear and unbalanced
classified as AC coupled, DC coupled and AC-DC coupled loads [8]. Using passive filters for power quality improvement
hybrid microgrids, DC coupled hybrid microgrid is considered poses many problems hence DVSI scheme consisting of volt-
for study in this paper is shown in Fig. 1. age source inverters (VSIs) is considered.
Due to the intermittent nature of renewable energy sources, In this work a pair of inverters i.e. DVSI along with
storage elements have become the integral part of microgrid DC microgrid system is considered. There are many parallel
to smoothen the power flow, to support islanded operation and inverter power sharing schemes available in literature [8],
used for energy arbitrage. Generally battery based energy stor- [9]. In [10] active load sharing scheme based on ISCT for
age systems are used in microgrid. But, they have a problem DVSI is proposed. But, using this DVSI control for microgrid
of poor power density, hence an additional energy storage applications requires power measurement of all sources and
device having high power density such as supercapacitor is sinks in a microgrid resulting in additional control complexity
used and such a combination is called as hybrid energy and increased sensor requirement. To overcome these draw-
‹,(((

,&5(5$ 
WK,QWHUQDWLRQDO&RQIHUHQFHRQ5HQHZDEOH(QHUJ\5HVHDUFKDQG$SSOLFDWLRQV 1RY%LUPLQJKDP8.

'&%XV $&%XV 3&& 3&&

8QEDODQFHG
'&'LVWULEXWHG 1RQOLQHDUORDG
*HQHUDWLRQ

7UDQVIRUPHU

7UDQVIRUPHU
*ULG
39 '& 3DUDOOHO
'& ,QYHUWHUV

$&
)8(/&(// '&
3RXWW
W
$&'LVWULEXWHG

3LQ 3GFW
*HQHUDWLRQ

'& '&/LQN
:,1' $&
*5,'
$& ,QYHUWHU ,QYHUWHU
',(6(/*(1 '&
6(7
'&
'&
'& 6XSHUFDSDFLWRU
+\EULG(QHUJ\
6WRUDJH6\VWHP

'&
'& '&
6XSHUFDSDFLWRU '& SY
'&
%DWWHU\
'& $& '&ORDG
%DWWHU\
/2$' /2$'

Fig. 2. Proposed topology.

Fig. 1. DC coupled hybrid microgrid.

[12]. The instantaneous power flow relationship across the DC

backs a new method is proposed for DVSI control parameter
link can be given as
extraction.
The remaining part of the paper is organized as follows: pin (t) = pdc (t) + pout (t) (1)
system configuration and control is described in Section II
which consists of DC link control, reference current gen- whereas the different power sources and sinks within the
eration, power management algorithm, improved dual VSI system are represented in (2) and (3), the bidirectional power
control scheme, state of charge limits of energy storage devices flow is denoted by the notation ” ± ”.
and switching pulse generation for various power converters .
Simulation results are presented in Section III. The conclusions pin (t) = ppv (t) ± pb (t) ± psc (t) − pdcl (t) (2)
are presented in Section IV. pout (t) = ±pg (t) − pacl (t) (3)

II. S YSTEM C ONFIGURATION AND C ONTROL where ppv(t) , pb(t) , psc(t) , pdcl(t) , pacl(t) , pg(t) are instan-
taneous PV, battery, supercapacitor, DC, AC load and grid
The grid connected hybrid microgrid considered for study
powers. The DC link power can be further divided into three
is shown in Fig. 2. Where the renewable energy source that
components i.e average power component pavg(t) , oscillatory
is PV is connected to common DC bus using a simple boost
power component posc(t) and transient power component
converter rather than a high gain converter thereby reducing
ptra(t) as shown below.
complexity. The hybrid energy storage system is interfaced to
DC bus using bidirectional converters [11]. Parallel combina- pdc (t) = pin (t) − pout (t) (4)
tion of GTI is used for bidirectional power flow between DC
= pavg (t) + ptra (t) + posc (t) (5)
and AC buses. Grid tied Inverters are interfaced to AC bus
using transformers which enables in reduced DC link voltage pavg(t) is the average power difference between PV and AC,
for microgrid operation, it also enables to use reduced voltage DC loads, this has to be shared between grid and battery.
rating switches and lower value of DC storage capacitor. Otherwise it results in linear increment or decrement of the
Thereby reducing the size of GTI. The transformer serves DC link voltage. The transient power ptra(t) is provided by
the purpose of voltage transformation, isolation as well as supercapacitor and the oscillatory power posc(t) is due to the
an inductive filter to eliminate the high frequency switching 100 Hz ripple is buffered by the DC link capacitor.
components generated due to the switching of power electronic
switches in the inverters. Both PV and load with dynamic B. Reference Current Generation
changes are considered to test the efficacy of the proposed
control strategy. The reference currents for various power converters can be
derived from the following effective current equation using PI
A. DC Link Control controller as shown below.

The DC link filter is implemented using capacitor which is ief (t) = Kp ve + Ki ve dt (6)
used to buffer (1) the 100 Hz ripple caused and (2) the input
and output power differences to make DC link voltage constant = iavg (t) + itra (t) + iosc (t). (7)

,&5(5$ 
WK,QWHUQDWLRQDO&RQIHUHQFHRQ5HQHZDEOH(QHUJ\5HVHDUFKDQG$SSOLFDWLRQV 1RY%LUPLQJKDP8.

Where ve = vdcref − vdc is the difference between reference Pacl , SOCb , SOCsc , iavg (t) are average AC load power, state
and actual DC link voltage, which arises due to input and of charge of battery, supercapacitor and average component of
output power difference in the DC link. DC link current.
Out of the three components of effective current, the average
component is obtained by passing through a low pass filter D. Improved Dual Voltage Source Inverter Control Scheme
and it is delivered/absorbed by grid/battery. These reference The proposed dual voltage source inverter consists of two
currents are used to generate switching pulses for all DC-DC three phase neutral point clamped inverters with split capacitor
converters and GTIs. topology connected to a common DC link. DVSI scheme offers
advantages like increased reliability and reduced filter size.
C. Power management algorithm Modified instantaneous symmetrical component theory
The proposed PMA decides the operating modes of the (MISCT) is used for power sharing among inverters. ISCT
microgrid as deficit power mode, excess power mode and was developed primarily for unbalanced and nonlinear load
floating power mode based on the value of iavg (t) compensation by active power filters. According to this theory
Consider deficit power mode in which the PV power is less the reference compensator currents [13] for unity power factor
than the sum of AC, DC load powers. Hence, the deficit power operation are given by Eq. (8).
has to be supplied either by grid/HESS based on SOC limits  
vs(abc)
of battery and supercapacitor. For example let the SOCbat > if (abc) = il(abc) −  2 Pl (8)
Lower Limit and SOCsc > Lower Limit then battery will j=a,b,c vsj
supply the entire average component of deficit power, so the where if (abc) , il(abc) , vs(abc) , Pl are filter and load currents,
power taken from grid is zero. Supercapacitor will supply the source voltages and average AC side load power. If a fraction
transient component of deficit power if there are any sudden of load power is supplied by grid then the above equation can
be modified as given below [10]. Which is called as modified
start instantaneous symmetrical component theory in this regard.
 
vs(abc)
if (abc) = (α)il(abc) − (β)  2 Pl (9)
Read Pacl, SOCb, SOCsc, iavg(t) j=a,b,c vsj

In this work a pair of inverters are considered so α = α1 +

Microgrid Deficit Mode
iavg(t) < 0
Microgrid Excess Mode α2 = 1 and β = β1 + β2 . Here α1 , α2 represents the fraction
of load currents compensated by inverter-1, inverter-2 and β
iavg(t) § 0, Floating Mode
represents
 the fraction of load power supplied by grid. The
β1
Lower limits of SOC Upper limits of SOC ratio of β2 depends on rating of the inverter-1 and inverter-
are considered for are considered for
comparison Upper limits of SOC 2. The value of β can be obtained by equating source currents
comparison
are considered for
comparison to iavg (t)sin(wt) with a phase shift of 120 degrees for each
phase. The expression for source currents obtained from the
Based on the actual SOC Based on the actual SOC Based on the actual SOC Fig. 4, is shown below.
values either grid or values either battery will values either grid or
battery will supply
deficiet power
be charged or remains
idle
battery will take excess
power
is(abc) = il(abc) − if (abc) (10)
and and and
super capacitor supplies super capacitor supplies super capacitor supplies upon solving the above equation gives the value of β as given
transient power transient power transient power
below.

K ∗ Vphrms ∗ iavg (t)
Generate reference β = β1 + β2 = . (11)
currents Plavg
From above equation it is clear that only AC load power
measurement is required rather than power measurement of
END
all sources and sinks in the microgrid as mentioned in [10].

Fig. 3. Power management algorithm flowchart.

LVDEF 3&& LODEF 8QEDODQFHGDQG
changes in PV or load. QRQOLQHDUORDG
Similarly, in case of excess power mode, when SOCbat > LIDEF
Upper Limit and SOCsc > Upper Limit then battery goes *ULG
in to idle condition, supercapacitor supplies the transient &RPSHQVDWRU &RPSHQVDWRU
component and the entire excess power is injected into grid. LQYHUWHU LQYHUHWHU
The proposed power management algorithm is represented
in the form of a flow chart as shown in Fig. 3. Where Fig. 4. Schematic of unbalanced, nonlinear load compensation.

,&5(5$ 
WK,QWHUQDWLRQDO&RQIHUHQFHRQ5HQHZDEOH(QHUJ\5HVHDUFKDQG$SSOLFDWLRQV 1RY%LUPLQJKDP8.

TABLE I
Thereby, overall system cost and complexity is reduced, which S YSTEM PARAMETERS FOR S IMULATION S TUDY
is a major contribution of this work. Where K is a constant
and α, β are called control parameters which decides reactive, Supercapacitor specifications Values
Terminal voltage (Vsc ) 16 V
harmonic, unbalance and active power sharing among parallel Max. peak current rate (Ip ) 200 A
inverters. Capacitance/pack (Csc ) 58 F
Max. continuous current (Imc ) 19 A
No. of packs in series 4
E. State of Charge Limits of Energy Storage Devices Battery specifications Values
Ah Capacity 14 Ah
State of charge of any energy storage device can be defined Terminal voltage (VB ) 12 V
as the ratio of remaining capacity over the nominal capacity of No. of batteries in series 4
DC load parameters Rdcl =200 Ω
the energy storage device. SOC is a key factor to characterize AC load parameters Values
the state of storage elements, to supervise the good use and Unbalanced linear load Ra = 135 Ω, La = 0.15 H
to contribute to enhance the lifetime of the energy storage Rb = 195 Ω, Lb = 0.24 H
Rc = 244 Ω, Lc = 0.30 H
devices (ESDs). Every ESD has upper and lower limits of
Nonlinear load 3-Φ bridge rectifier with
SOC within which storage devices have to be operated. There Rl = 400 Ω,
are several techniques for SOC estimation. However, coulomb Total DC link capacitence Cdc = 1000 μF
counting principle is suitable for all battery systems and easy DC link voltage of inv1 , inv2 Vdc =100 V
Grid/source voltages 3-Φ 208 V
to implement [14]. The SOC expressions for ESD computed Transformer parameters Values
using coulomb counting method is mentioned below, Rating 1000 VA
 Primary winding resistance, inductance 0.0025 Ω, 0.25 mH
1 Secondary winding resistance, inductance 0.01 Ω, 1 mH
SOCj = SOCj0 − ij dt. (12) Magenetising resistance, inductance 40 Ω, 0.127 H
3600CJ
Where ij , SOCj0 , and CJ are current, initial state of charge
and nominal capacity of ESD respectively. A. Microgrid Deficit Power Mode
In this mode PV power is less than sum of AC, DC
F. Switching Pulse Generation for Various Power Converters loads. Hence, the deficit power is supplied by HESS/grid. The
variations in PV current and DC load are shown in Fig. 6(b).
The reference currents generated in section II-B are com- Based on the SOC values of battery and supercapacitor shown
pared with the actual values and the error is given to PI in Fig. 6(e), the deficit power is shared by grid/battery under
controller. The output of PI controller is given to PWM block steady state and the transient change in PV power is absorbed
to generate switching pulses with a switching frequency of by the supercapacitor packs, this can be explained more clearly
20 KHz. For all DC-DC converters and for grid tied inverters in Fig. 6(d) showing zoomed view of various powers at t =
(GTIs) the error is given to hysteresis controller with a band 1 sec where there is sudden change in PV power. However,
of 0.1 to generate switching pulses as shown in Fig. 5. battery is idle because it’s SOC is less than the lower limit as
shown in Fig. 6(e).
This increase in PV power was transferred to load by DVSI
i.e inverter-1 and inverter-2. Thereby, reducing the grid power
and supercapacitor acted for sudden change in PV power. The
reactive power sharing among DVSI, grid and AC load is given
in Fig. 6(f). Battery and supercapacitor currents are shown in
Fig. 6(g). Three phase grid currents are shown in Fig. 6(h),
after t = 2 sec grid currents become zero since battery supplies
the deficit power. The zoomed version of unbalanced, non-
linear load currents is shown in Fig. 6(i). The zoomed version
of grid currents shown in Fig. 6(j) are sinusoidal and in phase
Fig. 5. Switching pulses generation.
with grid voltages as shown in Fig. 6(k) thus demonstrating
unbalanced and nonlinear load compensation.
B. Microgrid Excess Power Mode
III. S IMULATION R ESULTS
In this mode PV power is more than sum of AC, DC
The proposed system is simulated using MATLAB based loads. Hence, the surplus power is absorbed by HESS/grid.
simulink environment for different operating modes of grid The variations in PV current and DC load are shown in Fig.
considering variations in pv power, load powers and SOC lim- 7(b). Based on the SOC limits of battery and supercapacitor
its. The system parameters for simulation study are mentioned shown in Fig. 7(e), the excess power is taken by grid/battery
in Table I. Following cases are considered for simulation under steady state and the transient change in PV power and
studies and they are as given below. load power is absorbed by the supercapacitor packs, this can

,&5(5$ 
WK,QWHUQDWLRQDO&RQIHUHQFHRQ5HQHZDEOH(QHUJ\5HVHDUFKDQG$SSOLFDWLRQV 1RY%LUPLQJKDP8.

 
,SY 


&XUUHQW$
&XUUHQW$


9ROWDJH9
 
9ROWDJH9

,SY
9GF  9GF
 
 
 ,GFO  ,GFO

  
  D   7LPH6    E   7LPH6    D   7LPH6    E   7LPH6 

3DFO  3SY

 3J 3E 3DFO
 3LQYLQY

3RZHU:
3RZHU:

 3SY 3GFO 3LQYLQY 

 3VF 3GFO
 3VF 3E

 3J
F  &

        7LPH6          7LPH6 

  3SY
 3J 3DFO 
 8SSHU 
62&VF 3LQYLQY 

3RZHU:
62&E 3DFO 62&VF
3RZHU:

 3SY  /LPLW 62&E 8SSHU

  /LPLW
62&

62&
3GFO 3VF  /RZHU  3GFO
 3LQYLQY 3VF  /RZHU
/LPLW
     /LPLW
 3E  3E 3J
  G   7LPH6    H   7LPH6    G    7LPH6   H   7LPH6 
 

5HDFWLYH3RZHU9$5
5HDFWLYH3RZHU9$5

 
4LQYLQY  ,E
4LQYLQY  ,VF

&XUUHQW$
4DFO
&XUUHQW$

 4DFO  
 ,E
4J 4J 
 ,VF  


 
I I J
   
    7LPH6    J   7LPH6      7LPH6      7LPH6 

 ,JDEF   ,JDEF 

&XUUHQW$


&XUUHQW$


&XUUHQW$



&XUUHQW$
 
   
   
 K   
K
       7LPH6    L  7LPH6         7LPH6    L  7LPH6 
9ROWDJH9 &XUUHQW$

9ROWDJH9 &XUUHQW$
 9VD
   9VD
&XUUHQW$

&XUUHQW$

   
   
   

 ,VD  
,VD
 M  7LPH6   N  7LPH6    M   7LPH6   N   7LPH6 

Fig. 6. Dynamic performance under microgrid deficit power mode: (a) Fig. 7. Dynamic performance under microgrid excess power mode: (a) DC-
DC-link voltage, (b) DC load and PV currents, (c) Various active powers link voltage, (b) DC load, PV currents, (c) Various active powers as per
as per labelling, (d) Zoomed view of powers at t = 1 sec, (e) SOC values labelling, (d) Zoomed view of powers at t = 1.24 sec, (e) SOC values of
of battery and supercapacitor including upper and lower limits, (f) Various battery, supercapacitor including upper and lower limits, (f) Various reactive
reactive powers as per labelling, (g) Variations in battery and supercapacitor powers as per labelling, (g) Variations in battery, supercapacitor currents, (h)
currents, (h) Grid current variations, (i) Unbalanced, non-linear load currents Grid current variations, (i) Unbalanced, non-linear load currents (j) Zoomed
(j) Zoomed view of grid currents at t = 1.5 sec, and (k) Phase ’a’ source/grid view of grid currents at t = 3.5 sec, and (k) Phase ’a’ source/grid voltage and
voltage and scaled version of current representing UPF operation. scaled version of current representing UPF operation but out of phase.

be explained more clearly in Fig. 7(d) showing zoomed view

of various powers at t = 1.24 sec where there is sudden change
in DC load power. However, battery is idle because it’s SOC currents are shown in Fig. 7(g). The variations in three phase
is less than the lower limit as shown in Fig. 7(e). grid currents are shown in Fig. 7(h). The zoomed version of
This increase in DC load power was supplied from PV and unbalanced, non-linear load currents is shown in Fig. 7(i).
remaining excess power was fed back to grid thereby increas- The zoomed version of grid currents shown in Fig. 7(j) are
ing the grid power and supercapacitor acted for sudden change sinusoidal and out of phase with grid voltages as shown in
in DC load. The reactive power sharing among DVSI, grid Fig. 7(k), thus demonstrating unbalanced and nonlinear load
and AC load is given in Fig. 7(f). Battery and supercapacitor compensation.

,&5(5$ 
WK,QWHUQDWLRQDO&RQIHUHQFHRQ5HQHZDEOH(QHUJ\5HVHDUFKDQG$SSOLFDWLRQV 1RY%LUPLQJKDP8.

C. Microgrid Mode Transfer [5] S. T. Kim, S. Bae, Y. C. Kang, and J. W. Park, “Energy management
based on the photovoltaic hpcs with an energy storage device,” IEEE
In this sub-section microgrid mode transfer i.e from deficit Transactions on Industrial Electronics, vol. 62, no. 7, pp. 4608–4617,
to excess is simulated by varying the PV current from 3 July 2015.
A to 13.5 A and keeping AC, DC load constant as shown [6] S. Kotra and Mahesh. K. Mishra, “Energy management of hybrid
microgrid with hybrid energy storage system,” in 2015 International
in Fig. 8(d). The variations in DC link voltage and battery, Conference on Renewable Energy Research and Applications (ICRERA),
supercapacitor currents are shown in Fig. 8(a), (b). During the Nov 2015, pp. 856–860.
deficit power mode, power is taken from the grid hence source [7] N. R. Tummuru, Mahesh. K. Mishra, and S. Srinivas, “Dynamic energy
management of renewable grid integrated hybrid energy storage system,”
currents are in phase with their respective phase voltages and IEEE Transactions on Industrial Electronics, vol. 62, no. 12, pp. 7728–
in case of excess power mode, power is injected to the grid 7737, Dec 2015.
hence the source currents are out of phase with their respective [8] R. Majumder, A. Ghosh, G. Ledwich, and F. Zare, “Load sharing
and power quality enhanced operation of a distributed microgrid,” IET
voltages as shown in Fig. 8(c). Renewable Power Generation, vol. 3, no. 2, pp. 109–119, June 2009.
[9] J. M. Guerrero, N. Berbel, J. Matas, L. G. de Vicuna, and J. Miret,
  “Decentralized control for parallel operation of distributed generation
9ROWDJH9

&XUUHQW$

  ,VF inverters in microgrids using resistive output impedance,” in IECON

9GF 
  2006 - 32nd Annual Conference on IEEE Industrial Electronics, Nov
  2006, pp. 5149–5154.
 ,E
 [10] M. V. M. Kumar, Mahesh. K. Mishra, and C. Kumar, “A grid-connected
 D    7LPH6  E    7LPH6 dual voltage source inverter with power quality improvement features,”
 IEEE Transactions on Sustainable Energy, vol. 6, no. 2, pp. 482–490,
9ROWDJH9 &XUUHQW$

9VD
 April 2015.
&XUUHQW$

 'HILFLW0RGH ([FHVV0RGH
 [11] J. Zhang, J.-S. Lai, and W. Yu, “Bidirectional dc-dc converter modeling
,SY

 and unified controller with digital implementation,” in Applied Power

,GFO Electronics Conference and Exposition, 2008. APEC 2008. Twenty-Third
  Annual IEEE, Feb 2008, pp. 1747–1753.
,VD
 F    7LPH6  G    7LPH6 [12] Y. M. Chen, H. C. Wu, Y. C. Chen, K. Y. Lee, and S. S. Shyu, “The
ac line current regulation strategy for the grid-connected pv system,”
IEEE Transactions on Power Electronics, vol. 25, no. 1, pp. 209–218,
Fig. 8. Performance under seamless mode change: (a) DC link voltage, (b)
Jan 2010.
Variations in battery and supercapacitor currents, (c) Phase ’a’ source/grid
[13] A. Ghosh and A. Joshi, “A new approach to load balancing and power
voltage and scaled version of current and (d) DC load and PV currents
factor correction in power distribution system,” IEEE Transactions on
Power Delivery, vol. 15, no. 1, pp. 417–422, Jan 2000.
[14] P. E. Hartz, L. Liu, and G. Zhu, “State of charge estimation for
IV. C ONCLUSION lion-lithium batteries using extended kalman theorem,” in Industrial
Informatics - Computing Technology, Intelligent Technology, Industrial
In this paper a new method is introduced for derivation of Information Integration (ICIICII), 2015 International Conference on,
DVSI control parameters which are used to generate reference Dec 2015, pp. 295–298.
currents to GTIs. This method makes DVSI scheme more
feasible interfacing option for power management in microgrid
environment. Simple power management algorithm is also
introduced for bidirectional power flow considering the SOC
limits of ESD’s and renewable power availability. Apart from
real power flow control additional power quality features like
current harmonic compensation, reactive power support and
unity power factor operation are achieved at the PCC by
compensating unbalanced and nonlinear loads.
V. ACKNOWLEDGEMENT
This work is supported by the ministry of science
and technology, DST India, under the project grant
SB/S3/EECE/056/2015.
R EFERENCES
[1] J. Salvatore., “World energy perspective, cost of energy technologies,”
World Energy Council, 2013.
[2] 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.
[3] S. Vazquez, S. M. Lukic, E. Galvan, L. G. Franquelo, and J. M. Carrasco,
“Energy storage systems for transport and grid applications,” IEEE
Transactions on Industrial Electronics, vol. 57, no. 12, pp. 3881–3895,
Dec 2010.
[4] K. Nikhil and Mahesh. K. Mishra, “Application of hybrid energy
storage system in a grid interactive microgrid environment,” in Industrial
Electronics Society, IECON 2015 - 41st Annual Conference of the IEEE,
Nov 2015, pp. 002 980–002 985.

,&5(5$