详细说明:
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here the
ript I is omitted for compactness in the
notation. In Appendix 3, the relationship between the Ku
L kW
transformation and the Park transformation is given in
detail The dynamic equations expressed with Park
variables are also included. The relationship between the
coefficients in the dynamic equations (3)and the steady-
state star equivalent circuit parameters in Fig. 1b is
M=x/01,=(x+x)/0
+‰)/a7
+X)/
The double-cage model of Fig. 1c using the Ku
218.61.41.2
080.6040.20
transformation [10] in the synchronously rotating reference
framc has the following transformed cquations
Figure 2 Torque-speed and current-speed curves for a
US=(R,+L: (p+ja))is+M(p+ja)i1+M(p+jo)i2
0=M(p+x)i+(R1+L1(P+xo)i1+M12(+io)i
could be concluded from the experimental
0=M(p+jso)i+M(p+json+(R2+L2(p+jso))
measurements that the single-cage model does not agree
T=2,M,Im(i(i1+边)5=(-90n)/o
ith the experimental data. Fig. 2 shows the torque-speec
and current-speed curves of a 1-kW motor for slip valu
(5) in the range s=(0, 2). The torque and current values are
normalised with the nominal torque, TN, and current, IN
where the superscript II is omitted for compactness in the rcspcctivcly. The cxpcrimcntal mcasurcments in Fig. 2 arc
notation
represented with small circles. The continuous line
represents the torque-speed and current-speed curves
Thc rclationship bctwccn thc cocfficicnts in the dynamic calculated with the double-cage model of Fig. 1b and the
equations (5) and the steady -state star equivalent circuit
parameters of Table 1
parameters in Fi
ig. lc is
These parameters are determined from the measured
M=Ym/ M12=(x12+rm)/w L,=d(x+rm)) torquc and current for diffcrcnt speeds. The non-lincar
equations used for finding out the double-cage parameters
L1=(412+Xm)/(L2=(+X12+Xm)/o
f the equivalent circuit of fig. 1b are
f(x)=(M()-C(k)=0
The induction motor is usually delta or isolated Wye connected
calculated considering that the motor is Wye connected it are
The parameters in the steady-state equivalent cird
f+n(x)=(I(k)-l()=0k
3 Experimental measurements
x=(Rl, R2, Xm, Xsd Xid) is the vector of the parameters
Expcrimcntal mcasurcmcnts of diffcrcnt squirrcl-cagc
n is thc numbcr of mcasurcments
induction motors of low-and medium-rated power are
studied. The steady-state measurements in Fig. 2 are made in
TM(sk and IMS) are the measured torque and ci
the laboratory of the Department of Electrical Engineering, values for k-1 to n
EUETTT-UPC. The steady-state measurements in Fig 3 are
realised in the abb laboratory, where there are five test
Tc(s) and Ic(se) are the calculated torque and current
beds for testing motors of 1-90 kw
values for k= 1 to n, using the vector of parameters x
The test bed used for testing the induction motors consisted
The stator resistance R s is measured and the equality
of the following main parts: a) loading machine and speed restriction X2d= xsd[4, 7]is used.The non-linear
controller (DC machine and DC adjustable speed drive); b) equations are solved with the Solve function of MATLAB
torque transducer mounted on the motor axis and speed and [11, which uses a non-linear least-square algorithm.
current sensors; c)variable three-phase source
2 shows that the agreement of the calculated torque
Thc torquc-spccd curvcs arc mcasured at rcduccd voltage, spccd and current-spccd curves with the expcrimcntal data is
m=U/V3, where U is the nominal voltag
very good. Fig 4 shows the total torque-
speed cllrve an
e
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torque-speed curves of the inner-cage (Ri, Xi)and the nominal point and the maximum torque. The single-cage
outer-cage(R2, X2)
Parameter determination is detailed in [7]
Fig 3 shows the torque-speed and current-speed curves
From Fig. 3, it can be noted that
five squirrel-cage induction motors. The experimental
measurements of torque and current at different speeds are
There is a good agreement between the experimental data
represented with small circles. The continuous line and the values of torque and current predicted by the double
represents thc tord
nd current calculated with thc
caac m
ouble-cage model of Fig. 1b, and the motor parameters
of Table 2 are calculated with (7). The broken line
A double-cage model is essential to predict available
represents the torque-speed and current-speed curves
starting torques
alculated using the single-cage model of Fig. la and the
single-cage parameters of Table 2. The single-cage
The single-cage model is clearly an inadequate model
parameters are obtained by using the information of the when the motor speed varies in a wide rar
8
90kW
90 kw
75kW
75 kW
48kw
4
48 k W
i7kW
37 kW
18.5kW
6
≈
18.5k
0
0.6
0.4
0.
0.4
Figure 3 Torque-speed and current-speed curves and measured torque and current data of five squirrel-cage induction
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Table 1 Double-cage parameters for a 1 kW induction
in PSCAD-EMTDC [12]. Only
conversion of
motor (U= 230 V)
parameters of an eight-Parameter model into a six-parameters
model is studied in [4. An algorithm to calculate the motor
R、1.05809
2.5286
10866
parameters from manufacturer data by using the equivalent
X115929x=x2d1.57119xd7.26329
circuit of Fig. 16 is developed in [7]. Therefore, it is
necessa
to know how to calculate the motor paramete
1g.
of the equivalent circuit in Fig. 1b are
ViCe versa
To simplify this conversion of
parameters, if the conditions
rll
Ouier-caye---so
R=R=和=X
(10
Inncr-cagc
一
are imposed, then the circuits of Fig. 5 must be equivalent
l81614l210.8063.40.20
These conditions can be imposed because, as discussed in [4]
Slip
the doublc-cagc modcl has only six independent paramctcrs
When a seven-parameter model is used, like the equivalent
Figure 4 Torque-speed curves for a 1 kw motor
of Figs. 1b and lG, one parameter can be
arbitrarily because there is a degree of freedom. The election
The real values of the motor parameters can be calculated
Xd= xsd, automatically implies the conditions Rs=Rand
from table 2 as
m. These conditions can be easily confirmed
imposing that the slip is null,s=0, in the equivalent circuits
RI=ZB R2=T2Zg X=xr
of figs. 1b and 1
14=A1d∠B
The input impedance of the circuit in Fig. 5u is
where the impedance base is
ZB=0/P
z(a,0)=1/(0+R()+1(i+2)(1)
U being the rated line voltage and p the rated mechanical
nd can be rewritten as
ower
32a2+ro2+a
(12)
4 Equivalent circuit parameter
z2(m,9)-n2oDl+5
determination
In [4], there is a detailed study of the equivalence between
diftcrcnt doublc-cage motor modcls with six, seven and cight
paramctcrs. In this study, only the equivalence bctwccn the
2+12R
equivalent circuit of Figs. 1b and lc is studied. The reason for
RI
Ri+R
this election is that these are the equivalent circuits most
3
widely used in practice. For example, the equivalent circuit of
c- RiRi d- Lia+ li
Fig. 1c is the model for the double-cage induction motor used
R1+R!
r1+R
Table 2 Parameters of double-cage model of Fig. 1b and single-cage model in p u. U=400 V)
P(kW)
Double-cage model
Single-cage model
2d
rd
90
0.00340.01300.11712.65950.06820.12060.00340.01162.63980.08250.013
75
0.00270.01000.1008309250.069201105000270.009130772008010010
0.0045001660.09601.92230.05790.14630.00450.0139189060.08060.016
37
0.00500.01230.11291.98600.05720.14790.00500010819518008700.013
18.5
0.00660.01710.15111.567100718
0.11860.00660.0151155370.08320018
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4.2 Parameter determination of circuit
rom circuit∥
Rs/
In this section the method of determining the parameters
circuit I from the parameters of circuit Ii is discussed
the parameters
nd d are known, and usins
Figure 5 equivalence between different models
the auxiliary parameters yi and y2, defined as
The input impedance of the circuit of fig. 5b is
y一2c2mV(12_4C
(19)
z(o,0)=1012+1(/s+1(m+R(14
2C cNv(bll2-4ACll
and can be rewritten as
hc paramctcrs of thc cquivalent circuit in Fig. 1b can bc
calculated as
z(o,)
5202a+isaB+C
js2aDll+s
(15)
R1
y1y
y1
where
ld= riyi l 2i= riv2
L1(R1+R)+
R +R
r+RIl
These relations are deduced in Appendix 2
6
4.3 Numerical examples
Tablc 3 shows the numcrical valucs of the paramctcrs of thc
Both circuits will be equivalent when
double-cage circuit in Fig. 1c, which are equivalent to the
parameters of the double-cage circuit in Fig. 1b in Table 2
B=bl CI
D1(17)
These parameters are the result of applying (10),(13 )and
(18)
4. 1 Parameter determination of circuit l
from circuit
5 Per unit system
In this section the method of determining the parameters of The parameters of the equivalent circuit of the squirrel-cage
circuit ll from that of circuit I is discussed. If the parameters induction motor are usually expressed in per unit(p. . )on
A, B, C and dare known, the parameters of the equivalent the notor base. This can lead to confusion because
circuit in Fig. 1c can be calculated as
although the use of p.u. quantities is common in the
literature, it is not always clear which base quantities are
(18)
In this study, base power is defined as Sb= P, where P is
R
r1+R
the rated mechanical power and the base voltage, UB, is the
R
line-to-line voltage. Other studies, such as 13 l, use the
t the
inal slip, Sr= sn, as b
These relations are deduced in Appendix 1
power. The relation between the rated mechanical power,
Table 3 Parameters of double-cage model in Fig. 1c
P(kW)
12
90
0.0034
0.0682
2.6595
0.0436
0.0495
0.0153
0.0940
75
0.0027
0.0692
3.0925
0.0426
00396
0.0118
0.0834
0.0045
0.0579
1.9223
0.0415
0.0506
0.0196
0.1274
37
0.0050
0.0572
1.9860
0.0412
0.0597
0.0136
0.1201
18.5
0.0066
0.0718
1.5671
0.0447
0.0611
0.0205
0.0924
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P, and the apparent power at the nominal slip, SN, is
Table 4 Estimated double-cage induction motor parameters
P=SNnPF
(21)
0362Pk0392
1=0.0713P0135
where m is the efficiency and PFis the power factor at nominal
2=01090604xm=12609Py
slip. A motor is always labelled according to its mcchanical
power. Therefore in the authors'opinion, it is more natural
x:=00519P8032x12=0.0379p0323
to use rated mechanical power as base power instead of the
x2=0160603
apparent power that must be given as additional data
Nominal power Pk in kW
Another source of confusion is the fact that the motor data
are divided by its rated values, like TM/TN, TST/TN, IST/IN, double-cage model in Fig. lc. The p u. system used in the
in addition, thc basc torquc and basc current arc not cqual to equations of Table 4 is defined as Sb=p, where P is the
the motor nominal torque and current
rated mechanical power (or nominal mechanical power)
and the base voltage, UB, is the line-to-line voltage. In this
On the base used in this study the relations between base
ay,the real values of the motor parameters can be easily
torque and nominal torque, and base current and nominal calculatcd using(8)and(9)
current are
The parameters of three notors using the equivalent
(22)
circuit in Fig. lc are shown in Table 5. They are calculated
N
nPF
using the equations of Table 4, with the values P:= 630,
90 and 11 kW. Tables 5 and 6 show motor data suitable
and on the base used in [13] the relations are
for the Explicit' and the EMTP Type 40, options
rcspcctivcly. Thc manufacturer data in Table arc
alculate
of table 5
TBMPF
The 'EMrp Type 40 option, which uses manufacturer
data, does not inform the user about the parameters of the
equivalent circuit obtained by the program (in the EMTP
6 Induction motor in PSCAD/
RV program, these parameters are shown to the user). To
EMTDC
identify the characteristics of the motor that the program is
using, the torque-speed curve in steady-state can be
The double-cage model of the induction motor in the
calculated with PSCAD/EMTDC
PSCAD/EMTDC program [12] has three data entries
named T ypical Data, 'EMTP Type 40 andExplicit'. The
The torque-speed curve of an induction motor can be
input datum in the Typical Data'option is motor power obtained by using an Electromagnetic Transient Program
and only three different options are given: P<. 10Hy
pcrforming a simulation whcrc spccd changes vcry slowly
10 Hp 500 Hp. The input data This can be achieved by setting a high inertia value. The
in the EMTP Type 40' option are manufacturer data. The conditions of the transient in PSCAD/EMTDC are
input data in the Explicit' option are the parameters of the
cquivalent circuit in Fig. 1c
30 s at zero spccd to allow clcctric transients to vanish
The Typical Data option is simple, as it has only three
60 s at zero torque, with a high inertia value chosen in
different cases. When the user knows the motor power such a way that the motor can reach the nominal speed at
ly, more realistic equivalent motor parameters can be
he end of the simulation
alculated with the equations of [14], which are applicable
to the double-cage model in Fig. 16. Table 4 shows an Fig. 6 shows the torque-speed curves calculated for the
cquivalent sct of cquations to dctcrminc the motor thrcc induction motors in Tablc 6. Each plot has thrcc
parameters as a function of the motor power for the curves, namely the torque-speed curve, calculated with the
Table 5 Parameters of double-cage model in Fig. 1c
P(kW)
12
630
0.0029
0.0732
2.8718
0.0467
0.0305
0.0064
0.0936
90
0.0062
0.0660
2,2399
00438
0.0395
0.0151
0.1102
0.0141
0.0590
1.7126
0.0410
00520
0.0380
0.1314
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Table 6 Manufacturer data(U=400V, f=50 Hz)
P(kW
P
M/N
IST/IN
630
0.8817
2.5639
1.5151
66697
0.0059
0.9904
90
0.8561
2.7351
1.9960
66380
0.0123
0.9792
11
0.8256
2.9740
2,4671
6.2774
0.0256
0.9533
obtaining correct parameters from manufacturer data can be
solved by using the algorithm of [7] and the conversion
630kW
EMTP Type 40
equations(18)
Figs. 6a and 6b show a slight difference in maximum
torquc betwcen the curve calculated with the stcady-statc
Equivalent circuit
equivalent circuit and the curve calculated with the
Explicit
licit option. This effect can be
a
the motor inertia. Fig. 7a shows the infuence of the inertia
value on the shape of the torque-speed curve. The figure
g0 kw
d by a solid line, a broken li
and a dotted line for values of the inertia constant
H=40 S, 10 s and 5 s, rcspcct
n Fig. 7b, the torque-speed curve in the zone near the
maximum torque is magnified (the range of the slip is from
s=0.2
0.025). It can be observed that for low
values of the inertia constant, H, a greater error occurs in
the value of the maximum torque
I1 kW
7 Induction motor in EMtP-Rv
The doublc-cagc modcl of thc induction motor in thc
EMTP-RV program [15 has two data cntrics namcd
'Basic and Enable nameplate input calculator. The input
data in the "Basic option are the parameters of the
Slip, s
equivalent circuit in Fig. 16. The input data in the
Figure 6 Torque-speed curves calculated using the
equivalent circuit, the ' EMTP Type 40'and the ' Explicit
630kW
2,0
options
10
steady-state equivalent circuit (shown by a solid line), the
00
torque-speed curve, calculated with the option Explicit
and the parameters of Table 5(shown by a broken line)
0.6
0.0
and the torque-speed curve, calculated with the option
EMTP Type 40and the parameters of Table 6(shown by
a dotted line). The values of the inertia constant, H, used
with the motors of 630. 90 and 11 kw are 40. 7.5 and
7.5 s respectively
ig. 6 shows that the Explicit option works correctly(the
Fi
resulting torque-speed and current-speed curves obtained
05
fit the manufacturer data: starting current and torque
maximum torque etc.), whereas the EMTP Type 40
20l750.150.1250.100750.050.0250-0,025
option in PSCAD/EMTDC does not. The starting torque
D
and current valucs arc similar to thc correct valucs but thc
maximum torque is very different. The problem of Figure 7 Influence of inertia on the torque-speed curve
118
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Table 7 Parameters of double-cage model in Fig. 1b
P(kW)
2
630
0.00117
0.06171
29742
0.05714
0.06171
0.00704
0.06418
90
0.00294
0.05972
2.5458
0.06890
0.05972
0.01666
0.08556
11
0.00837
0.06214
2.1835
0.08082
0.05214
0.04482
0.12564
Enable nameplate input calculator'are the manufacturer
Fig. 8 plots the torque-speed curve of three motors of 630,
ata. In this option, thc paramctcrs of the cquivalent 90 and 11 kW. Thc correct torquc-spccd curve calculatcd
circuit in Fig. 1b are calculated using the algorithm in using the equations of the steady-state circuit with the
[16]. The manufacturer input data that the user must parameters of Table 5 is represented by a solid line. The
introduce in the progran does not include Maximum incorrect torque-speed curve calculated with the equations
torque Therefore the algorithm does not use the of the steady-state circuit using
arameters of Table 7
maximum torque, and the torque-speed curve calculated
given by the EMTP-RV program is represented by a
with the parameters supplied by the 'Enable manufacturer
broken line. Fig. 8 shows clearly that maximum torque of
input calculator will be incorrect
the torquc-spccd curve calculatcd by EMTP-RV is too
high. This is bccausc the algorithm in [16 docs not usc
Table 7 shows the double-cage parameters given by the
the maximum torque as the input data
EMTP-RV program by using the entries in Table 6. The
parameters in Table 7 are in per unit. The base power is
the apparent power at the nominal slip, SB
8 Conclusions
Experimental data confirm that the double-cage model must
be used to obtain realistic models of the squirrel-cage
induction motor because the single-cage motor produces
30 kW
very large errors. Moreover, manufacturer data always show
Nameplate input calculator
a starting torque that cannot be fitted to the single-cage
model. The equivalence between the two most common
linear double-cage models is analysed and the relation
between their parameters is obtained. The induction motor
Equivalent circuit"
in PSCAD/EMTDC is studicd; and the EMTP Typc 40
option to calculate motor parameters using manufacturer
data is shown as not working correctly. A similar problem
is found in the EMTP-RV program
4_90kW
9 Acknowledgments
The authors acknowledge the financial support of the
Comision interministerial de Ciencia
Technolo
gT
(CICYT) under the project DP12004-00544. The authors
also thank Amalia Barrera and Francesc Quintana from
Asea Brown Boveri, S. A. Fabrica de motores for
IkW
providing the experimental data of the motors in Fig. 4
3
10 References
[1] LEVY. General method of magnetizing flux saturation
modelling in d-q axis models of double-cage induction
nachines,IEE Proc. Electr. Power Appl., 1997, 144,(2)
pp.101-109
Figure 8 Torque-speed curves calculated using the [2 PEDRA J, SAINZ L : Parameter estimation of squirrel-cage
equivalent circuit with the parameters of table 5 and the induction motors without torque measurements, /EE Proc.
parameters calculated by Emtp-Rv
Electric Power Appl., 2006, 153,(2), pp. 263-270
lET Electr. Power Appl., 2009, Vol 3, Iss. 2, pp. 111-122
119
doi:10.1049/ let-epa20080043
C The Institution of Engineering and technology 2009
www.ietdl.org
[3] VAS P. 'Electric machines and drives. A space-vector (14), can also be written as
theory approach(Clarendon Press, Oxford, 1992)
pp.279-280
7(a,S orl isaa+6
24
[4] CORCOLES F, PEDRA J, SALICHS M, SAINZ L. Analysis of the
nduction machine parameter identification, IEEE Trans
Energy Conver.,2002,17,(2),pp.183-190
[5] SUDHOFF S.D.,ALIPRANTIS D.C,KUHN BT,CHAPMAN PL
3o2L14+o(12+a)+b
Experimental characterization procedure for use with an
Z(o, s)
advanced induction machine model, IEEE Trans. Energy
Conver,2003,18,(1),pp.48-56
where the comparison with(15)rcsults in
[6] SMITH A C, HEALEY R C, WILLIAMSON S. ' A transient induction
motor model including saturation and deep bar effect,IEEE
Trans. Energy Conver 1996, 11,(1), pp.8-15
R1+(26)
[7 PEDRA J, CORCOLES F 'Double-cage induction motor
parameters estimation from manufacturers data IEEE If the circuits of Figs. 5a and 5b are equivalent, the
Trans. Energy Conver, 2004, 19,(2),pp. 310-317
impedances(12)of Fig. 5a and (25)of Fig 5b must be
equal. The comparison between both equations results in
[8http://www.energy.wsu.edu/software:Motormaster+
Ver 4.0, Washington State University Energy Program
L12+a
(27)
[9]http://energyefficiencyjrcceceu.int/eurodeem:Euro
DEEM 2000, European Data base of Efficient Electric Motors The first and the fourth relation allow Ll to be obtained
[10」 LESENNE」, NOTELET F, SEGUIER G:‘ Introduction a
I'Electrotechnique Approfondie. Paris: Technique
Documentation 1981
D)L1+
(28)
[11 The Math Works, Inc. MATLAB 5.3 and Simulink 3.0,
Natick, MA, 1999
The division of the first relation by the third of(26)and using
the second and fourth equations of (27)
[12]Manitoba HVDC Research Center: 'PSCAD/EMTDC
Jser's Manual Guide, Version 4, 2004
bILI
(29)
[13]JOHNSON B.K., WILLIS J.R. Tailoring induction motor
analytical models to fit known motor performance
characteristics and satisfy particular study needs, IEEE
ds./EEE From the second relation of(26)and the third of(27),we
Trans. Power Systems, 1991, 6, 3), pp. 959-965
havc
[14] PEDRA J. ' Estimation of typical squirrel-cage induction
motor parameters for dynamic performance simulation
/EE Proc. Gener Transm. Distrib., 2006, 153, (2), pp 137-146
ri-b ri- cI
(3
[15] EMTP Development Coordination Group: EMTP-RV, Finally, from the third relation of(26)and the fourth of(27)
2003
we obtain
[16 ROGERS G. SHIRMOHAMMADI D. Induction machine
modeling for electromagnetic transient programIEEE
L=d(R1+R2)=D(R1+R)(31)
Trans. Energy Conver, 1987, 2,(4),pp 622-628
11 Appendix 1
12 Appendix 2
In this appendix, the parameters of the equivalent circuit in In this appendix, the parameters of the equivalent
Fig. lc arc deduced from thc quantities, A, B, C and D. circuit in Fig. 1b arc deduced from the quantities
The input impedance of the equivalent circuit in Fig. 5b, C and D)
120
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