IEEE TRANSACTIONS ON POWER DELIVERY, VOL. 23, NO. 2, APRIL 2008
1113
Control of a Stand-Alone Inverter-Based Distributed
Generation Source for Voltage Regulation and
Harmonic Compensation
Hiren Patel and Vivek Agarwal, Senior Member, IEEE
Abstract—Operation of a distributed-generation (DG) source,
producing sinusoidal output voltage and supplying nonlinear loads
is characterized by a nonsinusoidal voltage at the point of common
coupling (PCC). The situation gets particularly aggravated during
the islanding mode, when the grid power is not available. This deteriorates the performance of other loads connected in parallel. A
scheme based on nonsinusoidal pulsewidth-modulated control of a
stand-alone inverter-based DG source is proposed to regulate and
produce a sinusoidal voltage at the PCC. It is demonstrated that
without any current sensor or compensating device, the individual
harmonic components and THD of the supply voltage at the PCC
can be reduced to the desired level. Simulations have been performed to study the viability of the proposed scheme and all of the
results are presented.
Index Terms—Distributed generation (DG), harmonics, nonsinusoidal pulse-width modulation (NSPWM), nonsinusoidal
voltage, point of common coupling (PCC), series compensation,
sinusoidal pulse-width modulation (SPWM).
I. INTRODUCTION
F
ROM the viewpoint of environmental protection and limited reserves of conventional fuels, distributed-generation
(DG) systems based on nonconventional energy sources, such as
photovoltaics (PV), wind, fuel cells, microturbines, etc. are expected to increase. With the increased deployment of distributed
resources (DR) into the grid, it is desirable and advantageous to
tap additional benefits out of these resources besides their main
function of active power generation. The feasibility of using DG
for power conditioning, power factor compensation, real and
reactive power control, and mitigation of other power-quality
(PQ) problems have been discussed in the literature [1]–[5]. Tam
and Rahman have proposed an interface of DG with the utility
to compensate reactive power [1]. A scheme to reduce PQ problems, besides reactive power compensation, has been presented
by Marei [2]. Ro and Rahman have demonstrated the use of DG
in improving the stability of the power system as well as for real
and reactive power control [3], [4]. A hybrid DG system based
on the PV–fuel-cell combination, which is capable of regulating
reactive and active power fed into the grid, has also been presented [5].
Manuscript received October 30, 2006; revised May 19, 2007. Paper no.
TPWRD-00682-2006.
The authors are with the Department of Electrical Engineering, Applied
Power Electronics Lab, Indian Institute of Technology-Bombay, Powai,
Mumbai 400 076, India (e-mail: [email protected]).
Digital Object Identifier 10.1109/TPWRD.2007.915890
Fig. 1. DG source interface with the loads at the PCC.
All of the work cited so far refers to the grid-connected operation of DG sources. To realize the full potential of DG units,
however, their operation under stand-alone mode (i.e., in an islanded mode, must also be investigated [6]). This is because the
system performance in stand-alone mode is more sensitive to
factors such as the control scheme of the DG, interface, types of
loads, etc., compared to grid-connected operation.
Fig. 1 shows the interface of an inverter-based DG unit oprepresents the rms value of the
erating in stand-alone mode.
ac voltage generated by the inverter. The DG source is tied to
the point of common coupling (PCC) through an inverter and a
series inductor having an inductance “ ” and an internal resistance “ ,” The series inductor is essential from the control and
protection point of view [7].
If the grid is live, the quality and magnitude of the voltage at
the PCC is decided entirely by the grid. As the grid imposes a
stiff sinusoidal voltage at the PCC, irrespective of the presence
of nonlinear loads, other loads connected at the PCC draw sinusoidal current. Thus, the presence of nonlinear loads does not
affect the performance of other loads connected at the PCC as
long as the grid is live. However, if the grid is not live and if
the DG source has to supply power to the loads connected at the
PCC, the presence of nonlinear loads affects the performance
of all the loads connected at the PCC. In this case, the nonlinear
, drawn by the nonlinear load, leads to a nonlinear
current
voltage drop
across the line impedance, given by
0885-8977/$25.00 © 2008 IEEE
(1)
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Fig. 2. Series compensation to compensate the voltage drop across line
impedance.
where is the fundamental component of
and
represents its th harmonic component.
Hence, even if the inverter is controlled to generate a sinusoidal output voltage, the voltage at the PCC
will be nonsinusoidal. This distorted voltage may lead to the
malfunctioning of the connected loads which may include harmonic losses and torque pulsations in motors, false tripping of
the relays, poor power factor operation of the loads, and a reduction in the lifetime of transformers, capacitor banks, etc. [8],
[9]. A similar scenario may occur if an ac source, with a relatively large internal impedance, is supplying a variety of loads,
including nonlinear loads.
The problem of distorted supply voltage at the PCC, as shown
in Fig. 1, can be handled by compensating the nonlinear drop
across the line impedance. The compensation voltages, required
to eliminate voltage harmonics, are injected across the compensating transformers’ secondary windings which are in series with the line [10]–[13]. Fig. 2 shows the series compensa, equal to the nonlinear drop
tion scheme, where voltage
across the line impedance, is applied externally in series with
the source to produce sinusoidal voltage at the PCC. A scheme
of series compensation with an inverter and a compensating
transformer to compensate voltage harmonics in a 1- system
has been presented by Perez et al. [11]. Peng et al. [12] highlighted the need for a series active filter where a shunt passive
filter alone is not adequate for compensation. Wang et al. [13]
presented a series active power filter (APF) for compensating
voltage-type harmonics where the reference signal of the compensation voltage needed by the series APF is obtained by detecting both source current and load voltage. A novel scheme, to
correct the voltage harmonics and to compensate the voltage imbalance on the load side in a 3- system, is proposed by George
and Agarwal [14].
All of the compensation schemes, cited in the previous parais
graph, refer to the case where the main voltage source
either the utility or an ac source. In addition, they require some
other compensating device (inverter), which produces the com. However, in an islanded mode of oppensating voltage
eration, where the island consists of an energy source based on
a power-electronic interface (usually an inverter), the inverter
and
. This paper
itself can be controlled to produce
IEEE TRANSACTIONS ON POWER DELIVERY, VOL. 23, NO. 2, APRIL 2008
deals with the islanded mode of operation of the DG source and
presents a compensation scheme in which a sinusoidal voltage
is produced at the PCC by operating the inverter using a nonsinusoidal PWM (NSPWM) control. Thus, instead of operating
the inverter to produce a sinusoidal output voltage, it is con[Fig. 2].
trolled to produce a nonsinusoidal output
This results in the cancellation of the nonlinear drop across
the line impedance to achieve a sinusoidal voltage at the PCC.
Though the DG source considered in this work is a stiff dc
source, the proposed scheme is valid for any nonconventional
energy source, such as the PV or a fuel-cell stack.
The proposed scheme has the following desirable features.
1) Inverters operating with sinusoidal pulse-width modulation (SPWM) generate a sinusoidal voltage and, hence,
require an extra compensating device. The proposed
scheme does not require any extra compensating device,
compensating transformers, or passive filters.
2) In general, series compensation schemes are based on
sensing the load current or the source current. Wang et
al., [13] have used current sensors to detect the source
current for generating compensation voltage. However,
the proposed scheme eliminates the desired voltage harmonics from the voltage at the PCC without using any
current sensors.
3) Besides reducing the total harmonic distortion (THD),
the scheme ensures that individual (desired) harmonic
components are reduced below the specified limit.
The remainder of this paper is organized as follows. Section II
explains the principle on which the proposed scheme works. It
describes the analytical background of the scheme to regulate
the voltage at the PCC and to compensate the harmonic voltage
drop across the line impedance. Section III gives the details of
the control scheme based on the analysis presented in Section II.
Section IV presents the simulation results. The major conclusions of the work are presented in Section V.
II. ANALYTICAL BACKGROUND
The principle involved to regulate and achieve a sinusoidal
supply voltage at the PCC is mathematically explained in this
section. Referring to Fig. 1, the voltage at the PCC is given by
(2)
where
, , and represent the vector quantities and consist of fundamental as well as harmonic components. is the
current supplied by the source (inverter). Hence
(3)
where
,
, and
represent the fundamental component of the source voltage, voltage at the PCC, and source cur,
, and
are the th-order
rent, respectively, while
harmonic components present in the source voltage, voltage at
the PCC, and source current, respectively. is the maximum
PATEL AND AGARWAL: CONTROL OF A STAND-ALONE INVERTER-BASED DG SOURCE
1115
order of harmonics which has to be eliminated. Rearranging (3)
yields the following:
(4)
(5)
Hence, if the second term on the left-hand side of (5) is made
zero, a sinusoidal voltage at PCC can be obtained. Thus, (5)
shows that in order to achieve a sinusoidal
, the following
condition should be satisfied:
(6)
where
(7)
Thus, to achieve a sinusoidal voltage at the PCC, each “ ”
), in
must be made zero.
harmonic component (
Hence, by monitoring these harmonic components (
) in
and injecting similar components from the source side,
can be reduced to zero. It is evharmonic components of
, thereby
ident from (5) and (6) that this will lead to
compensating the nonlinear drop across the line impedance on
the source side. This can be done by comparing each harmonic
with the desired (tolerable) level
, recomponent
as given below
sulting in the error voltage
(8)
where , given by (8), is then applied to the individual proportional-integral (PI) controller whose output is multiplied with a
sine wave at the respective harmonic frequency and delayed by
an angle identical to that of the phase of that harmonic in the
output voltage. This results in the corresponding “reference har, which can be used to modulate the
monic component,”
sinusoidal reference waveform of the sinusoidal PWM scheme
. Thus
to eliminate the th harmonic from the
(9)
where
and
are the proportional and integral constants
is the amplitude of the th harmonic component with
while
which the reference sinusoid waveform of SWPM is to be modulated. Here, modulation refers to the addition of the “reference
harmonic components” to the reference sinusoid waveform of
in series with
SPWM for inserting the nonlinear voltage
(Fig. 2).
Fig. 3. System configuration with NSPWM control.
Thus, the undesired harmonic components can be eliminated
by modulating the reference sinusoidal wavefrom the
form with their dedicated harmonic reference waveforms as
given by (8) and (9). These reference harmonic components
in such a way that a
modulate the sinusoidal reference
particular harmonic component is produced in the output of
the inverter which opposes its counterpart on the load side.
The resulting reference waveform is a nonsinusoidal reference
, which is used for comparison with a carrier
waveform
triangular waveform. Therefore
(10)
III. CONTROL SCHEME
Fig. 3 shows a single-phase inverter operating in islanded
mode and supplying various loads connected at the PCC. Due to
, drawn by the nonlinear loads,
the nonlinear current,
becomes nonsinusoidal. The NSPWM controller takes
as the input and generates a nonsinusoidal reference waveform
) for firing the switches
through
of the inverter. This
(
nonsinusoidal reference is compared with a triangular waveform
to generate PWM signals as shown in Fig. 4. The inverter fired
with these PWM signals acts as a nonsinusoidal voltage source
at the PCC. The
to produce a desired sinusoidal voltage
details of the NSPWM controller block are shown in Fig. 4.
The detailed control scheme, as shown in Fig. 4, consists of
two main loops, referred to as the “voltage control loop” and
“compensation loop.” The voltage-control loop regulates the
voltage at the PCC. The PI controller of this loop adjusts the
amplitude of the sinusoidal reference waveform and, thus, controls the modulation index as is done in a conventional sinusoidal PWM (SPWM) technique. The compensation loop modulates the sinusoidal reference waveform with the harmonic frequencies present in the load current to generate a nonsinusoidal
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IEEE TRANSACTIONS ON POWER DELIVERY, VOL. 23, NO. 2, APRIL 2008
Fig. 4. Schematic diagram of the control scheme to achieve voltage regulation and harmonic compensation. HG to HG represent the harmonic generator blocks.
reference
. This nonsinusoidal reference, as in the case of
SPWM, is compared with a repetitive high-frequency triangular
waveform.
The controller requires information only about the voltage
at the PCC to generate the nonsinusoidal reference waveform
and the angle
of
discussed before. The magnitude
each harmonic component, present in
, are derived using
the “Harmonic Calculator” shown in Fig. 4.
This information is then passed on to the “Harmonic Generator” blocks. The number of “Harmonic Generator” blocks required depends on the desired THD in the voltage at the PCC.
Fig. 4 shows the “harmonic generator” blocks for 2nd through
th harmonic components. The PI controllers of these harmonic
generators adjust the amplitude of the respective reference harmonic components (defined in Section II) into the reference
waveform. The reference value, set for all of these PI controllers
which should be less than 0.03 (Fig. 4 shows the
is
to limit the individual harmonic components to 1%). This is the maximum limit for an individual
harmonic component, which the utility can provide to the users,
as recommended in the revised IEEE-519 standard [15]. Thus,
these loops ensure that the individual harmonic components in
the voltage at the PCC are brought to the levels recommended by
the standards. The error voltage, given by (8), is applied to the
individual PI controller whose output is multiplied with the sine
wave at the respective harmonic frequency. It is also delayed
by an angle identical to that of the phase of that harmonic in the
output voltage. This forms the “reference harmonic component”
given by (9). Thus, each harmonic block produces its respective reference harmonic components. The reference harmonic
components generated by these “harmonic generator” blocks
obtained from the
are added with the sinusoidal reference
“voltage control” loop to produce a modulated nonsinusoidal
given by (10).
reference waveform
TABLE I
DETAILS OF LOADS CONNECTED AT PCC
IV. SIMULATION RESULTS
The scheme discussed before is simulated with MATLAB/
Simulink and the results of the simulation are presented in this
section. The loads considered (as an example) for the simulation
study are comprised of the following loads connected in parallel
and
connected in
at the PCC: 1) resistive load ( ); 2)
series; and 3) nonlinear load consisting of a rectifier with a large
filter (smoothening) capacitor and supplying a resistive load.
The details of the loads are given in Table I.
(Fig. 3) for the simulation is
The input dc supply voltage
is set at
considered to be 300 V. The reference voltage
100 V, to achieve an rms voltage of 100 V at PCC. Fig. 5 shows
the results when the reference waveform is sinusoidal (i.e., the
operation is similar to that of SPWM). In this case, the presence
of nonlinear load leads to a highly distorted voltage waveform
at the PCC [Fig. 5(d)].
under these conditions
The harmonic spectrum of
is shown in Fig. 6. It represents the relative amplitude of the
th-order harmonic voltage (
) with respect to that of the
fundamental, which is 140 V under these conditions. It shows
the dominance of 3rd-, 5th-, and 7th-order harmonics with their
relative amplitudes of 0.157, 0.0525, and 0.0505, respectively.
under these conditions is 18.6%. It is also
The THD of
mainly consists
observed that the harmonic spectrum of
PATEL AND AGARWAL: CONTROL OF A STAND-ALONE INVERTER-BASED DG SOURCE
Fig. 5. Performance of the system with SPWM control. (a) Current drawn by
the nonlinear load. (b) Inverter’s output current. (c) Reference waveform for
SPWM. (d) Voltage at the PCC.
Fig. 7. Performance of the system in the presence of the proposed NSPWM
controller: (a) Current drawn by the nonlinear load. (b) Inverter’s output current.
(c) Reference waveform for NSPWM. (d) Voltage at the PCC.
Fig. 8. Harmonic spectrum of
NSPWM conditions.
Fig. 6. Harmonic spectrum of V
with nonlinear loads and SPWM control.
of odd harmonics. The reason for the absence of even harmonics is the quarter-wave symmetry of the load current shown
in Fig. 5(a).
Figs. 7 and 8 display the operation under NSPWM conditions. The scheme gradually modulates the reference waveform
by introducing the harmonic components in it. The controller
adapts to the nonlinear load conditions and gradually removes
. Fig. 7(c)
the unwanted harmonic components from
shows the modulated reference waveform while Fig. 7(d)
shows the voltage waveform at the PCC. In less than 90 s, the
THD is reduced below 5%. Fig. 7(d) shows that not only does
the voltage at the PCC resemble a sinusoidal waveform, but
it also approaches the peak value of 141 V, indicating an rms
voltage of 100 V (equal to the desired value) at the PCC.
Fig. 8 shows the harmonic spectrum with the NSPWM
scheme which shows that the magnitude of individual harmonic
components is reduced to the set reference value of 1%. In this
case, the highest order voltage harmonic compensated using
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V
with nonlinear loads while operating in
TABLE II
PROPORTIONAL AND INTEGRAL CONSTANTS USED FOR THE PI CONTROLLERS
the scheme is 15th (i.e., compensation applied to the first seven
odd harmonics). THD can be reduced further by using a greater
number of harmonic generator blocks. With compensation
applied to just the first five odd harmonics, the scheme reduces
the THD to 6.5%. The proportional and the integral constants
used for the PI controllers in the scheme are given in Table II.
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IEEE TRANSACTIONS ON POWER DELIVERY, VOL. 23, NO. 2, APRIL 2008
Fig. 9. Response of the system under SPWM control with a significant linear
and voltage THD
load. Apart from the 3rd and 5th harmonic components, V
are also plotted.
Fig. 10. Operation under the NSPWM scheme with a significant linear load.
(a) Relative amplitude of the third harmonic. (b) Relative amplitude of the fifth
harmonic. (c) Voltage at the PCC. (d) THD of voltage at the PCC.
TABLE III
COMPARISON OF THE HARMONIC SPECTRUM
UNDER SPWM AND NSPWM OPERATION
Fig. 9 shows the performance of the system when operating
and
. Under
under the SPWM scheme with
these conditions, the current drawn by the linear loads is a significant portion of the total current supplied by the source. Hence,
is comparatively less than the prethe total distortion of
is still 12.34%. Also,
vious case. However, the THD of
the relative amplitudes of the 3rd and 5th harmonics, 0.11 and
0.0425, are higher than that specified by IEEE 519. The relative
amplitudes of the various harmonic components under the two
schemes are given in Table III.
Figs. 10 and 11 exhibit the operation with the same load conand
), but
ditions as that used for Fig. 9 (
with the NSPWM scheme. Here, the compensation is applied
for the first five odd harmonics. It is observed from Fig. 10 and
decreases to 2.8% within 60
Table III that the THD of
s. Fig. 11 shows that unlike the SPWM operation, the relative
amplitude of the third and fifth harmonic components is 1%.
Table III shows that all other harmonics are also reduced to 1%.
Fig. 12 shows the performance of the system in the absence
of the
of the controller and in a case when the resistance
nonlinear load changes from 10 to 5 . THD, in the absence of
the controller, is 22% and the third-, fifth-, seventh-, and ninth-
Fig. 11. Magnified view of Fig. 10. (a) Relative amplitude of the third harmonic. (b) Relative amplitude of the fifth harmonic. (c) Voltage at the PCC. (d)
THD of voltage at the PCC.
Fig. 12. System response in the absence of any compensation. R = 5 . (a)
Current drawn by the nonlinear load. (b) Inverter’s output current. (c) Reference
waveform for SPWM. (d) Voltage at the PCC.
order harmonic components have relative amplitudes of 0.195,
0.039, 0.0495, and 0.0494, respectively.
PATEL AND AGARWAL: CONTROL OF A STAND-ALONE INVERTER-BASED DG SOURCE
Fig. 13. Performance at high nonlinear load current. R = 5 . (a) Current
drawn by the nonlinear load. (b) Inverter’s output current. (c) Reference waveform for NSPWM. (d) Voltage at the PCC.
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Fig. 14. THD response to a step change in load at t = 88:3 s. Variation in the
relative amplitudes of the third and fifth harmonic components is plotted along
with the variation of the THD.
TABLE IV
COMPARISON OF HARMONIC SPECTRUM UNDER SPWM AND
NSPWM OPERATION WITH HIGHLY NONLINEAR LOAD
Fig. 15. Load current (I
), reference current (I ) generated by the controller, compensation current (I ) produced by inverter, and the grid current
) provided deficit active power demanded by the load.
(I
Fig. 13 shows the performance of the controller under highly
nonlinear load conditions depicted in Fig. 12. Here, compensation is applied for the first ten odd harmonic components. Under
these highly nonlinear load conditions, the THD is reduced to
7% against 22% observed in Fig. 12 without any compensation.
Table IV shows the comparison of SPWM and NSPWM operations with this load.
Fig. 14 shows the performance of the NSPWM controller to a
step change in the nonlinear load. Compensation is considered
of
for the first five odd harmonic components. Resistance
the nonlinear load suddenly changes from 10 to 5 at
s. Due to the step change, the THD suddenly increases to 22%
s. However, it subsequently reduces and attains the
at
value of 8.5% in 82 s (i.e., at 170 s) under the action of the
NSPWM controller.
Though the work mainly targets the islanded mode of operation, an illustration is considered without detailed mathematical analysis, showing the typical control scheme required for a
DG source to operate in the grid-connected mode. The proposed
NSPWM controller modulates the reference sine wave with the
harmonic components, similar to those present in the voltage at
the PCC. In the grid-connected mode, where the voltage at the
PCC is sinusoidal, the proposed controller works as an SPWM
Fig. 16. (a) Active power balance when the grid is connected. (b) Voltage at
the PCC and load current during islanded operation under steady state.
controller. Thus, the case is similar to two ac sources connected
in parallel and supplying linear and nonlinear loads, sharing the
sinusoidal and nonsinusoidal current components required by
the loads. To prevent the grid from supplying the nonsinusoidal
current to the load, it is preferable to operate the inverter as a
shunt active filter.
Figs. 15 and 16 show the simulation results for the DG opand
eration in the grid-connected mode (with
). Fig. 15 shows the various current waveforms in the gridconnected mode. It is observed that in the grid-connected mode,
the controller generates nonsinusoidal reference current which
is of the same nature as the load current. Inverter current tracks
this reference current and, thus, satisfies the reactive power as
well as the harmonic current demand of the local loads and
makes the grid free of harmonics. Fig. 16(a) shows that the active power demand of the load is about 2.5 kW which is greater
than the 2-kW active power supplied by the DG. So the remaining active power is drawn from the grid at the unity power
factor.
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IEEE TRANSACTIONS ON POWER DELIVERY, VOL. 23, NO. 2, APRIL 2008
Islanding occurs at
s and the control is transferred
to the NSPWM controller and the reference current generator
is deactivated, as shown in Fig. 15(b). The voltage at the bus
no longer remains sinusoidal. Due to this, the nature of the load
. Gradcurrent changes from what it was before
ually, however, the reference sinusoidal voltage waveform is
modulated by the NSPWM controller and magnitudes of individual harmonics as well as the voltage THD are brought within
limit. The voltage THD after islanding is about 12.5% which reduces to 4% within 50 s and all other harmonic components are
restricted to 1%. Fig. 16(b) shows the load current (when the
voltage THD has been reduced to 4%) which is similar to that
before islanding.
V. CONCLUSION
Nonlinear loads connected at the PCC cause a nonlinear drop
across the line impedance and, hence, distort the supply voltage
available at the PCC. This problem gets more pronounced
during islanding.
In this paper, a scheme based on the NSPWM technique has
been proposed which is capable of compensating the nonsinusoidal drop across the line impedance and producing regulated
sinusoidal voltage at the PCC. Not only is the THD reduced, the
individual harmonic components are also reduced to a specified
level. The only input that the controller requires for its operation is the voltage at the PCC. A notable feature of the proposed
algorithm is that it does not require any current sensor or any
other external compensating device. Also, it does not require
the load and line parameters’ values. The THD of the voltage
at PCC is dependent on the number of harmonics extracted and
introduced into the nonsinusoidal reference waveform. To compensate “ ” harmonic components present in the voltage at PCC
“ ,” harmonic generator blocks are required. However, most of
the loads (like the one considered) present quarter-wave symmetry where only odd harmonics are present. Hence, in such
cases, the “harmonic generator” blocks are required only for the
odd harmonics. This minimizes the number of harmonic generator blocks and reduces the mathematical analysis which might
have to be implemented using a high-speed digital signal processor (DSP) working as a harmonic generator. The satisfactory
performance of the controller is demonstrated using the simulation results obtained in MATLAB/Simulink.
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Hiren Patel received the B.E. degree in electrical engineering from the S.V.
Regional College of Engineering and Technology (now S.V. National Institute
of Technology), South Gujarat University, Surat, India, in 1996 and the M.Tech.
degree in energy systems from the Indian Institute of Technology, Bombay
(IITB), Mumbai, India, in 2003, where he is currently pursuing the Ph.D.
degree in electrical engineering.
His research interests include computer-aided simulation techniques, distributed generation, and renewable energy, especially energy extraction from
photovoltaic arrays. Currently, he is an Assistant Professor at Sarvajanik
College of Engineering and Technology, Surat.
Vivek Agarwal (SM’01) received the Bachelor’s degree in physics from St.
Stephen’s College, Delhi University, the M.Eng. degree in electrical engineering
from the Indian Institute of Science, Bangalore, India, and the Ph.D. degree in
electrical and computer engineering from the University of Victoria, Victoria,
BC, Canada, in 1994.
He was briefly a Research Engineer with Statpower Technologies, Burnaby,
BC, Canada. In 1995, he joined the Department of Electrical Engineering, Indian Institute of Technology–Bombay, Mumbai, India, where he is currently a
Professor. His main field of interest is power electronics. He works on the modeling and simulation of new power converter configurations, intelligent control of power-electronic systems, power-quality issues, electromagnetic interference/electromagnetic-compatibility (EMI/EMC) issues, and conditioning of
energy from nonconventional sources.
Dr. Agarwal is a Fellow of the Institution of Electronics and Telecommunication Engineers and a Life Member of the Indian Society for Technical Education.