40
IEEE Transactions on Energy Conversion, Vol. 8, No. 1, March 1993
STEP TOWARDS IMPROVEMENTS IN THE CHARACTERISTICS OF SELF EXCITED INDUCTION GENERATOR
L. Shridhar, Bhim Singh
Department of Electrical Engineering
Indian Institute of Technology - Delhi
New Delhi-110 016, INDIA
Abstract - Given due consideration to
the increasing use of Self Excited Induction
Generators (SEIGs) in isolated power plants, an
attempt is made to effect suitable design
modifications in standard induction motor to
improve its performance as SEIG. This paper
explores the theory behind such improvements
and sets the concept of voltage regulation in
SEIG.
Typical results of the
sensitivity
studies performed are presented and inferences
are drawn to suggest guidelines for real design
problem of such generators.
INTRODUCTION
With the growing demand of isolated power
units, Self Excited Induction Generator (SEIG)
is rapidly establishing itself in portable
gensets and non-conventional energy plants due
to its lower cost and overall maintenance and
operational simplicity. Absence of dc source,
inherent overload
protection and
improved
performance due to low transient impedance are
some
of its operational
advantages
over
conventional generators. Further in SEIG, cage
type machine offers simple and rugged brushless
rotor
construction with
less
maintenance
requirements.
By now the theory and operating principle
of SEIG is well established in the literature
of electrical engineering M - 6 ] .
Induction
machine basically being singly excited, requires reactive power for its operation.
If
connected to grid it draws necessary VAR from
the lines. But in case of its operation as
SEIG,
a VAR generating unit
should
be
connected
across its terminals, which
is
generally realised in the form of capacitor
banks.
With suitable capacitors
connected
across its terminals and with rotor
driven
in either direction by a prime mover, voltage
builds up across the terminals of the machine
due to self excitation phenomenon leaving the
machine operating under magnetic saturation at
some stable point. Mhen
the load connected
across the machine terminals is varied the
terminal voltage reduces considerably with the
load, implying its inherent voltage regulation
problem, which is more severe than that
of
alternator and dc generator. Therefore,
use
of
a
suitable regulator scheme
becomes
desirable for exploiting the potentials of SEIG
for power generationAlthough the principle of self excitation
of induction machine has been known since the
92 WM 020-8 EC
A paper recommended and approved
by the IEEE Energy Development and Power Generation
Committee of the IEEE Power Engineering Society for
presentation at the IEEE/PES 1992 Winter Meeting,
New York, New York, January 26 - 30, 1992. Manuscript
submitted August 23, 1991; made available for
printing December 16, 1991.
C S. Jha
Vice Chancellor
Benaras Hindu University
Varanasi-221 005. INDIA
thirties C13, it was not evident till recently
as to how the load, excitation
capacitance,
speed and various machine parameters interact.
The
analysis
of
machine
behaviour
is
complicated owing to the magnetic saturation
in the machine
and
the
need to choose
suitable
parameters for the given level of
saturation. Murthy etal C7] gave an analytical
technique
using Newton- Raphson method
to
identify the saturated magnetic reactance and
generated frequency of a self excited induction
generator for a given capacitance, speed and
load. The technique is very effective in the
analysis of such systems and has been widely in
use
since then for studying performance of
SEIG under different operating conditions [7123. Though core loss in the machine
is
neglected it can be accounted for by suitable
extension of the analysis C133- In the same
paper effect of various system parameters wore
studied
to suggest guidelines for
system
design. In a subsequent paper C8 3, the VAR
requirement of SEIG was estimated to obtain
desired voltage regulation. Elder etal C9] used
the same analytical technique to evaluate the
static VAR source available to control the
machine excitation for
a
variety
Of
operating
schemes.• It can further be seen
that since the early days studies on SEIG are
centered around the choice of proper regulating
schemes and their designs C13-203.
There are mainly three popular voltage
regulating schemes for SEIG which use switched
capacitor, variable inductor and saturable core
reactor, respectively [9,14]. The first one
is a simple and cheap scheme, where additional
capacitors
are
switched-on as
the
load
increases. Variable inductor or saturable core
reactor is used with single valued capacitor
bank SEIG. Switching of capacitors or variation
in inductor or reactor value can be obtained
by manual operation or by closed loop schemesusing relay/contactor or semiconductor switches
M S ] . Conrolled rectifier - inverter schemes
have also been proposed for asynchronous tie
with grid and for constant terminal voltage and
frequency
supply in isolation
C15,18-203.
Rating, duty and complexity of these regulators
depend
on
no load and
full
load
VAP
requirements of the generator.
A special feature of SEIG is that a
standard induction motor gives a corresponding
level of performance in generating mode also.
But, for quite sometimes, due to growing cost
and complexity of regulating schemes, the need
has
been
felt
to
attempt
at
design
modifications in induction machine to improve
its generating characteristics. The sensitivity
studies performed in ref. C7] and the studies
carried out on suitability of using normal
induction motor as SEIG [9] were the attempts
in this direction. In a later paper M 1 3 ,
design
specifications/details of the machine
were
utilised
to
predict
its
performance as SEIG. In the above papers design
modifications were suggested to reduce VAR
requirements of the generator resulting in
reduced
capacitance and lower
cost.
The
41
emphasis was laid on system studies, design of
regulator and the manner in which the VAR
generating unit should be controlled to match
the requirements of the reactive power of the
SEIG with the load. However, no attempts seem
to have been made to improve the regulation of
the generator alone and to effect performance
improvements with reduced role of regulator in
the system. For example, taking the case of a
switched capacitor scheme, guidelines have been
suggested to reduce the value of capacitance
connected across the generator but not much has
been
said about reducing the
number
of
switchings required to provide VAR compensation
from no load to full load. Moreover, the
criterion adopted and the guidelines suggested
need some modifications. It may also be noted
that
the
design modifications
required
for
reduced VAR requirement
and that for
improved regulation of the generator alone are
not identical.
Therefore,
this
paper is
aimed
at
investigating improvement possibilities in the
regulating characteristics of SEIG
through
suitable
design modifications.
Theory
is
presented to lay the foundation and to explain
the philosophy of improvements in the characteristics. Well known Newton Raphson method has
been used for the analysis of SEIG. With
suitable
modifications in
the
analytical
process, various programs were developed to
study different aspects of SEIG. As a first
step towards design modifications, sensitivity
analysis of the machine in terms of
its
equivalent circuit parameters has been carried
out and inferences are drawn, which can be
further translated into design process. Proper
concept of voltage regulation in SEIG has been
developed
after investigating its
typical
characterist ics.
For economical, reliable and robust power
system, it is desired that
consumers
maintain a power factor around unity. The power
companies therefore, recommend installation of
various power factor improvement devices to
meet this necessity and impose heavy penalty
for violating the power factor norms. Hence, in
the present paper, using a generalised analysis
technique, results are presented for resistive
loads. The results presented in graphical and
tabular forms are discussed suggesting useful
guidelines for the designer. The discussion
highligts the performance of the SEIG alone and
also as a system using switched
capacitor
scheme.
BASIC THEORY
The
primary elements
that
influence
regulation of the SEIG are its resistances and
leakage reactances. Therefore, these parameters
automatically become choice for sensitivity
study for design modifications. As the load
increases, the drop of voltage across
these
elements become prominent and the
already
weakened excitation provided by fixed valued
capacitor bank, along with other supplementary
processes futher reduce the terminal voltage
drastically to result in poor regulation. To
maintain the terminal voltage to a desired
level additional capacitance is required to
compensate the increased VAR requirement at
higher loads. The use of a soft core saturable
reactor
connected
in parallel
with
the
capacitor has been suggested
for improved
regulation of SEIG C4]. This is altogether a
different way of tackling the problem, which in
effect
is meant to flatten
the
overall
magnetisation characteristics of the system.
For a designer aiming to improve the regulation
of SEIG this could be an important clue.
Design modifications should be carried out in
such
a
way
that
this
magnetisation
characteristics of the combination of SEIG and
saturable core reactor is simulated as closely
as possible by the newly designed machine
alone. That is to say, the effect of saturable
core reactor should be incorporated inside the
machine. This may influence other performance
indices of the generator and therefore, the
design may be a little constrained.
ANALYSIS
The present study uses the standard steady
state equivalent circuit of the SEIG with the
usual
assumptions C7-12D, considering
the
variation
of
magnetising
reactance
with
saturation as the basis for calculation. The
equivalent circuit is normalised to the base
frequency by dividing all the parameters by the
p.u. self-excited frequency as shown in Fig. 1.
->
'
-:L x .c.
|X
(\
F2
n,
<
•F-V
Fig. 1 Equivalent circuit of Induction generator with load
where
R
R
= per phase stator
and rotor
resistance referred to stator
X s ,X r
= per phase
stator and
rotor
leakage reactance referred to stator
Xm
= magnetising reactance
Xc
= per phase capacitive reactance
of the terminal capacitor C
R.
= per phase load resistance
F,y
= p. u. frequency and speed
Is,Ir,IL= per phase stator, rotor and load
current, respectively
Vt,V
= terminal and airgap voltage
(all reactances referred above relate to the
base frequency f)
As
already mentioned the
magnetising
characteristics of the machine is of prime
importance in the analysis. Fig. 2 shows such a
characteristic
of the machine
considered,
relating the airgap voltage and
frequency
ratio (V /F) to the magnetising reactance. The
S
.Vg/F
O6
t
tS
Xm (p.u.)
Fig. 2 Variation of Vg/F with Xm
42
saturation portion of this characteristic can
be
linearised and expressed mathematically
in
the form 171 :
V /F =
K
1-
(1 )
^2Am
Where K^ and K2 depend upon design and
material of the machineFor the purpose of obtaining required
lagging reactive power to maintain desired
terminal voltage, XQ and F are the only unknown
parameters for a given speed and
load.
To
evaluate these parameters the loop equation for
the current (I,.) can be written as :
(2)
where
(3)
(4)
(5)
jX
jXmCRT,+ j <F-V)Xr,3
(6)
Z-, =
Since under steady state operation of SEIG
can not be equal to zero, therefore :
This equation after separation into real
and imaginary parts, can be rearranged into two
nonlinear equations which are solved using
Newton Raphson method to obtain value of Xc and
F as detailed in ref. [73.
After obtaining X and F, the following
relationships are used to compute generator
performance at particular load and speed:
(8)
I = CV /FD/CZ,,
S
g
!
I
=
<-v
F)
(9)
l
lr J
(10)
(11)
Input power P i n
= -3 ! Ir*2..
! R r F/ CF-» 3
Output power P o u t = 3 !
2,,
(12)
(13)
A similar mathematical model C123 can be
developed to obtain performance of SEIG for a
given value of capacitance and speed, where Xm
and F will be the unknown parameters.
scheme. A highly interactive package using all
these programs have been developed
offering
wide flexibilty to the choice and range of
parameters for sensitivity studies and
to
predict various performances of the machine.
CONCEPT OF VOLTAGE REGULATION IN SEIG
Effects
of
various
parameters
were
presented in graphical form in ref.
C73 and
power capability of SEIG was estimated for
different
sets of parameters using the same
value of capacitance. The same curves were used
to draw inferences on frequency regulation
to
suggest design modifications. But
in actual
practice the value of capacitance required,
changes over a wide range for different sets of
parameters
or
different
designs.
Hence
performance comparision for different
designs
need
to be made using the
corresponding
capacitor
connected across the
terminals.
Further good commercial practice and requirements of customers demand a generator to work
within a close voltage tolerance band. Due to
the use of same capacitance value for different
designs
there
is
considerable
variation
in the terminal
voltage level.
In
most
of the cases peak of the generator output power
lies outside the permitted voltage band.
And
therefore,
in general
the
maximum
power
capability
of the generators (Pm> can not be
utilised.
The maximum usable power (P ') of
generator is then the power at
which the
terminal
voltage
falls
to
the
minimum
permissible level, as shown in Fig. 3; where
P_'<
Pm- Since voltage regulation as defined
with respect to alternator or dc generator is
not applicable to SEIG, it is required to set
proper criterion for its voltage regulation. Pm
may seem to be a good contender
in this
respect, but due to the reasons mentioned above
and also due to the overlapping curves as shown
in Fig. 3, it can be noted that the
set of
parameters which give higher P may not give
higher power within a band and hence may result
in reduced regulation. Therefore, the criterion
that
the design giving higher peak power will
also have a better regulation does not
stand
true
in all
cases.
However,
with the
definition of a voltage tolerance band,
which
appears
logical
in
practice, the set
of parameters which gives maximum usable power
also gives a better regulation. It can also be
seen
that
set of parameters
for
better
regulation vary as the permissible voltage band
is changed. Since the utility permit a voltage
fluctuation of 1695, a voltage band between
V m a x =1.06 p.u.
and v m j n = 0 - 9 4 p.u.
has been
considered in this paper.
The
capacitance
value considered in individual design is the
. Terminal Voltage {p.u.)
PROGRAM DESCRIPTION
Using the generalised analytical
method
discussed above, various computer programs were
developed to calculate performance of SEIG
under different operating conditions. Given the
equivalent circuit parameters as inputs, Xm is
calculated for any load which in turn is used
to obtain the required VAR, value of capacitance and various other details. The capacitance
for the maximum permissible voltage level
is
chosen at this stage and is used to evaluate
the load characteristics of SEIG for the sensitivity studies. Another program simulates the
performance of SEIG with a switched capacitor
a s 0.4 0.6 a e <X7 0.8
02
Output Power (p.u.)
Fig. 3 Effect of leakage reactance on terminal voltage
43
one required to get V x at no load. The
regulation is estimated in terms of the maximum
usable power P m ' at V m i n .
VAR
RESULTS AND DISCUSSION
In this paper the experimentally obtained
data
of a standard three phase, four pole
delta connected, 3.7KW cage induction
motor
(as
detailed in appendix) is used to study
the effect of its parameters on its performance
as SEIG. To effect variation in the parameters
a factor 'q' has been used. The parameter under
study is multiplied by 'q' which is varied to
get desired effect. Though the studies were
carried out over a wide range of 'q', results
are presented only for a small range of variations because of the practical limitations.
As regarding the variation of magnetisation characteristics, instead of varying Xm in
its entirety; the remodelling of the characteristics has been carried out by varying the
parameters K1 and Kg •
ass
02
a4
as
as
i
Output Power (P-u)
Fig. 4(b) Effect of stator resistance on VAR requirement
Terminal Voltage (p.u)
Vmax
Vmln
Effect of Machine Parameters
Along with the studies carried out for
design modifications on regulating characteristics of SEIG, effect of machine parameters was
also observed on VAR requirement of the generator, since it is an important performance index
of SEIG. VAR demanded by the generator has
been studied from no load to full load
with
the terminal voltage maintained at 1.0 p.u.
o
as
cu
o.e
Output power (p.u.)
Fig. 6(a) Effect of leakage reactance on terminal voltage
V A R «>•"•)
Effect of Resistive Elements
load
Figs.
4(a) and 4(b)
show the
characterisics of SEIG for different values of
is seen that there is a marginal improvement in
voltage regulation and a marginal reduction in
VAR
requirement of the
generator.
Rotor
resistance also has a similar effect.
Effect of Leakage Elements
The family of load characteristics for
different
values
of
leakage
reactance
(X =X s =X l r ) is shown in Figs. 5(a) and 5(b).
While lower X l r improves the regulation, it is
seen that effect of leakage reactance on VAR
requirement of the generator at lower and
higher loads are at reverse, with the crossover
taking place around the full load. It has also
been observed that for small changes in X l r on
the either side of standard value <'q'=1.0),
the VAR demand at full load increases
except
for 'q' < 0.5 for which it starts decreasing
with lower values of X,
l
lr"
Terminal voltage In p.u.
0.4
as
02
as
Output Power In p.u.
Fig. 4(a) Effect of stator resistance on terminal voltage
ass
o
02
a4
as
as
i
._
.
Output Power (P>u)
Fig. 6(b) Effect of leakage reactance on VAR requirements
Effect of Magnetisation Characteristics
For a small change in K1 there is a
significant change in generator performance as
shown in Figs 6(a) and 6(b). A reduction in K1
causes substantial improvement in regulation
but increases the VAR demand significantly.
Kg seems to be a less sensitive parameter
than K 1 . It causes a marginal change in regulation but reduces VAR requirement significantly
for a small reduction in its value as shown in
Figs. 7(a) and 7<b), respectively.
As it is clear from the above trends, the
changes required
for better regulation and
that for lower VAR requirements of the machine
are different. A design that gives good voltage
regulation not necessarily requires lower VAR
also. The same is displayed in
Table-I with
desirable effects in performance for particular
swing in parameters being underlined.
Table-I
is
used
to
Impress
the
desirability for better regulation and lower
VAR requirements of SEIG. For various set of
parameters, it shows maximum usable power (Pm1)
for permitted voltage fluctuation of +6* and
44
Terminal Voltage (p.u.)
Terminal Voltage In p.u.
0.2
04
Output Power (p.u.)
Fig. e(a) Effect of Kt on terminal voltage
aa
02
at
aa
Output Power (p.u)
Fig. 7(a) Effect of K« on terminal voltage
VAR
VAR
((>•"•)
aa
aa
aa
t
Output Power (Pu.)
Fig. 7(b) Effect of Ks on VAR requirement
a4
aa
as,
,•
Output Power (P-u)
Fig. 6(b) Effect of K, on VAR requirement
a«
the no load and full load VAR requirements of third set gives generator with lower VAR requirements. The fourth row gives set of parameters
SEIG
(vflRo a n d V A R f i . respectively)
with
terminal voltage held at 1.0 p.u- The table for improved regulation and lower VAR. The last
also gives the initial capacitance(C o ), full set of parameters is chosen such that no additional switching is required. As shown in Fig.
load capacitance(Cfj), compensating capacitance(A C) and the number of additional steps 8(a), in contrast to the four step operation of
required for a SEIG system using switched standard induction motor as SEIG using a switccapacitance scheme. The last column of the hed capacitance regulator scheme, just a single
table shows the generated frequency
for the valued capacitor bank is sufficient for the
generator with new set of parameters to deliver
various designs at 1.0 p.u. output power.
Table-II gives various sets of parameters power upto full load, thus suggesting possibilinferred from Table-I. The second set gives ity of a self regulating SEIG. And it is this
design for better voltage regulation while the design to which the modifications should be
Tabl e - I
Parameter
selected
•
P
m'
Watts
q'
*
0 .8
1 .2
0 .8
1 2
0.8
1 .2
0 .8
1 .2
0 .8
1 .2
k
R
X
X
K
r
lr
lr
1
1
K2
K
K2
1550
1660
1467
1692
1458
1679
1464
2060
1223
1546
1578
(VAR)Q
2693
2689
2698
2691
2696
2 74 7
2642
4705
1857
2194
3175
Reactive Power
(VAR)fl
A(VAR)
3820
3 756
3916
3770
3894
3829
3850
6774
2690
3194
4467
1127
1067
1218
1079
1 198
1082
1208
2069
833
1000
1293
Capac it ance (J^F)
C
C
o
fl
^C
18.0
16-0
18.0
18-0
18.0
18.5
17.6
33.0
12-1
13-6
21.2
Additional
steps
25.2
22-8
25.3
22.8
22.3
23-8
23.9
7.2
4-8
7.3
4-8
7.3
5.3
3
2
3
2
3
3
5.3
3
41 .0
16.2
20-6
29.3
8.0
4. 1
1
4
7.0
3
3
8. 1
Frequency
p. u.
0. 958
o.960
0. 957
0- 96 7
0. 948
0. 954
o.959
o.951
o.961
0- 961
0- 958
* for standard set of parameters
Table - II
R
*set-I
set-II
set-Ill
set-IV
set-V
s
1.0
0 .8
0 .8
0 .8
0 . 75
Value of 'q'
Rr X l r
K1
1.0
0 .8
1.0
0.8
0 .8 0.8
0 . 7 0.8
0 . 7 0.7
1 .0
0• 8
1 .2
0 .9
0 .7
K2
1.0
1.2
0.8
0.7
0.75
R sact ive Power
P
Capac it ance (J^F)
IP"
<
C
iC
Watts (VAr) ( (VAr) f l A(VAr) C o
fl
1550
2650
1416
2342
3710
26?3
5681
1514
2562
6398
3820
7551
2111
3495
9066
1127
1970
59 7
933
2668
18.0
40.0
9-9
17.7
48.3
25.2
49.8
13-2
20-8
48-3
Additional
steps
Fr eq.
P- u.
7.2
9.8
3
1
0. 958
0. 960
0- 970
o.968
0- 961
33
4
3. 1
1
0-0
0
45
Terminal Voltage (p.u.)
Terminal Voltage (p.u.)
Frequency (p.u.)
(or standard parameters
_._._
o
0.1
02
08
0.4
for new parameters
as ae
ar
Output Power (p.u.)
Fig. 8(a) Load characteristics of SEIG
aimed at to improve performance of SEIG. In
true sense, it would be required to vary the
parameters in such a way that the increase in
the VAR requirements due to improvements in
is
K
regulation
for reduced values of
compensated by the reduced VAR requirements for
new values of other parameters.
Effect of machine parameters
on
the
generated frequency is not as much as it is on
terminal voltage or VAR requirements of the
SEIG.
However,
rotor resistance
is
the
parameter
which
effects
the
frequency
considerably
L61 .
A reduction
in
rotor
resistance improves the frequency regulation of
the generator. This is a good feature since the
above discussion recommends lower value of
rotor resistance. Fig. Q'.b) shows the variation
of terminal voltage and generated frequency of
the SEIG with load, for standard and new set of
parameters
with the corresponding no load
capacitance connected across the terminals.
From
the
foregoing
discussion,
the
magnetic
circuit
seems to be
the
most
influencial part of the machine for
such
designs. Therefore, while attempting proper
design modifications in standard motor for its
improved operation as SEIG, the designer needs
to
concentrate
more
on
magnetising
characteristics of the machine. The effect of
resistive and leakage elements individually may
not be appreciable but it is desirable to
choose their minimum possible values since
collectively their effect is significant. The
higher the swing in parameters
available,
better will be the design. It should not be
difficult at least in the case of
rotor
resistance and leakage reactance since for a
standard induction motor, their values are
usually chosen higher to increase the starting
torque
and
to
limit
starting
current,
respectively; which are perhaps not
valid
recommendations for SEIG. Additionally, the
availability of new less lossy C21] materials
further
ease constraints by allowing
the
machine to be operated in super saturation.
o
o.a 0.4 as ae 0.7 as as
1
Output Power (p.u.)
Fig. 8(b) Voltage and frequency regulation characteristics
0.2
suitable reduction in VAR demand, the stage is
set for the designer to use his skill and
experience to redesign a complete new line of
machines. As new theories, better materials and
improved manufacturing techniques are being
developed, how best the effects discussed above
would be translated into the practical design
problem will largely depend on the approach and
technique
adopted,
as a result
of
the
requirements and limitations to be met and the
availability of the practical reference data
and design. At present the authors are engaged
in gathering requisite information
through
close interaction with machine manufacturers
and it is intended to offer for publication in
future practical design of three phase SEIG
including the cost comparision of specially
designed generator and a
normal induction
motor used as SEIG.
REFERENCES
[1]
E. D. Bessett and F. M. Potter, "Capaciti-ve excitation for induction
generator",
AIEE Trans.. pp. 540-545, May 1935-
C2]
C. F. Wagner, "Self excitation of induction motors", AIEE Trans - .
vol. 58,
pp. 47-51, February 1939.
C3]
J. E. Berkle and R. W. Ferguson, "Inducti-on generator theory and application",
AIEE Trans.. pp. 12-19, February 1954.
[4]
B. C. Doxey, "Theory and application of
capacitor-excited induction generator",
The
Engineer. no. 29, pp.
893-897,
November 1963.
C5]
D. W. Novotny, D. J. Gritter and G. HStudsmann, "Self excitation in inverter
driven induction machine", IEEE Trans- on
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[6]
J. M. Elder, J. T. Boys and J. L.
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in
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I£E.
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171
S. S. Murthy, O.P.Malik, and A. K. Tandon
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C8]
S. S. Murthy, 0. P. Malik and P. Walsh,
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VAR requirements of
self
excited induction generators to achieve
desirable voltage regulation", presented
at the IEEE Conference on Industrial and
CONCLUSIONS
Equivalent
circuit
parameters
of
a
standard induction motor being the basis of
anlysis;
theory
and concept
of
voltage
regulation in SEIG has been developed. Having
identified effect of various parameters, it has
been observed that the changes required in the
design for improved regulation and that for
reduced VAR requirements of the machine are
different.
With the conflicting demand for effecting
suitable design modifications in SEIG
for
improved regulation in commensuration
with
0.1
46
Commercial Power Systems. Milwaukee, 1983.
C9]
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C, no. 2, pp. 33-40, March 1984.
C10D S. S. Hurthy, H. S. Nagaraj and Annie
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analysis
of
self
excited
induction
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Proc.IEE. vol. 135, pt. B, no. 1, pp.8-16,
January,1988.
C11J S. S. Murthy, B. P. Singh, C. Nagamani and
K. V. V. Satyanarayana, " Studies on the
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pp. 842-848, December 1988.
C123 S. P. Singh, Bhim Singh and M. P. Jain,
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utilization of a cage machine as capacitor
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90 SM 284-0 EC,presented at the IEEE/PES
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C14] M. B. Brennen and A. Abbondati, "Static
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C153 J. Arrillaga and D. B. Watson, "Static
power
conversion
from
self
excited
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125, no. 8, pp. 743- 746, August, 1978.
C16D D. B.
Watson,
and
R.
M.
Watson,
"Microprocessor control of a self excited
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Engg. Ed.. vol 220, pp. 69-82, 1985.
C173 F. Bim, J. Sjazner and Y. Burian, "Voltage
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526-530, 1989.
[183
S. S. Murthy, "Experience
with
the
analysis, design and control of induction
generators operating in' autonomous or grid
connected mode", in the Proceedings of the
International Conference on Evolution and
Modern
Aspects of Induct ion
Machine.
Torino (Italy), July 8-11, 1886.
[19] D. B. Watson, J. Arrillaga and T. Densem,
"Controllable d.c. power supply from wind
driven self excited induction machines",
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December, 1979.
C2O3
G. Raina and 0. P. Malik, "Hind energy
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and Systems. vol. PAS-102, no-12, pp.
3933-3936, December 1983.
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APPENDIX
Base Quant it ities
Power - 3.7 KW, Voltage/phase - 415 Volt
Current/phase- 4.39 Amp, Frequency - 50 Hz
Base VAR = Base Power
Equivalent Circuit Parameters
R = 0.053 p.u., Rr = 0.061 p.u.
X._ = X^ = 0.087 p. u.
: 0.3418
L. Shridhar was born in Bhilainagar, HP (India) in 1966
He received his B.E. degree
from Maulana Azad College of
Technology, Bhopal, and the
M.Tech degree from Institute
of Technology- Banaras Hindu
University, Varanasi.
He is with the department of
electrical engineering, Indian Institute of
Technology - Delhi since July 1990
and
is
presently, a full time research scholar working
towards his Ph.D. degree. His areas of interest
are electrical machines and their efficient
conversion.
Dr. Bhim Singh was born
at
Rahamapur, UP in 1956. He
received his B. Tech. degree
from University of Roorkee,
and M.Tech and Ph.D. degrees
from Indian Institute
of
Technology, Delhi in 1977,
1979 and 1983, respectively.
From 1983 to 1990 he was with the department of electrical engineering, University
of
Roorkee. At present he is Assistant Professor
at Indian Institute of Technology, Delhi.
He has over 60 papers to his credits in
the field of CAD, Power Electronics and Analysis and Control of Electrical Machines.
Prof. C- S Jha. was born at
Vijainagar in Bihar (India)
in 1934 and educated
at
Patna
University,
Indian
Institute
of
Sciences,
Bangalore,
Heriot
Watt
College, Edinberg
(U.K.),
and
Bristol
University
(U.K.). Has been a Professor
of Electrical Engineering at Indian Institute
of Technology- Delhi since 1964.
He has made singnificant contribution in
electrical machine theory and applications and
published a large number of papers. Has been
involved in planning and administration of
technical education in India since early 1970s.
He was Director of the prestigious I IT at
Kharagpur (1974-78), was Educational Advisor to
the Government of India on technical education
planning and has been active in curriculum
planning
and
development
of
engineering
education in India. Has been visiting professor
in many universities in the West, a member of
the board of Trustees of Asia Institute of
Technology, Bangkok (1974-86) and is a member
of
UNESCO international meeting group
on
continuing education of engineers since 1975.
At present, he is the Vice Chancellor of
the Benaras Hindu University at Varanasi.