Electric Machines and Drives by Miroslav Chomat - HTML preview

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198

200

202

204

(e) t(s)

Fig. 12. PBC-(a) Regulated Motor speed and its reference. (b)Generator speed. (c) DFIG & IM

rotor position. (d) Generator torque (e) Motor desired torque.

Figure 12 presents the mechanical IM speed and its smooth reference, the mechanical DFIG

speed, the DFIG and IM rotor positions, the DFIG torque τG and the IM desired torque τMd.

The real IM speed tracks the reference very well, i.e. low overshoot and no steady state error

are observed. Figure 13 shows the stator currents isa and isb, and their references over a suitable period of time. The stator currents do not track exactly their desired values but are

bounded. This is because the goal of the PBC is to track the IM speed and to keep internal

signals bounded.

Figure 14 shows the DFIG rotor currents irGa and irGb, and their references over a period of time. Again, these currents are sinusoidal and bounded.

Figure 15 presents the DFIG rotor voltages vrGa and vrGb, the IM rotor speed ωmM and its estimation ˆ

ωmM, the estimated IM load torque ˆ τML, and the estimated IM speed, given by

From Dynamic Modeling to Experimentation of

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133

20

10

(A)

sGb

0

& i

i sGa

−10

−20

193.74

193.76

193.78

193.8

193.82

193.84

193.86

193.88

193.9

193.92

193.94

(a) t(s)

20

10

(A)

d

sGa

0

& i

i sGa

−10

−20

193.74

193.76

193.78

193.8

193.82

193.84

193.86

193.88

193.9

193.92

193.94

(b) t(s)

20

10

(A)

d

sGb

0

& i

i sGb

−10

−20

193.74

193.76

193.78

193.8

193.82

193.84

193.86

193.88

193.9

193.92

193.94

(c) t(s)

Fig. 13. PBC-(a) isa, isb (b) idsa, isa (c) id , i

sb

sb

.

15

10

(A)

5

rGb

0

& i

−5

i rGa

−10

−15

193.74

193.76

193.78

193.8

193.82

193.84

193.86

193.88

193.9

193.92

193.94

(a) t(s)

50

(A)

d

rGa

0

& i

i rGa

−50

193.75

193.8

193.85

193.9

193.95

194

194.05

(b) t(s)

50

(A)

d

rGb

0

& i

i rGb

−50

193.75

193.8

193.85

193.9

193.95

194

194.05

(c) t(s)

Fig. 14. PBC-(a) irGa, irGb (b) id , i

, i

rGa

rGa (c) id

rGb

rGb.

134

Electric Machines and Drives

60

40

(V)

20

rGb

0

& v

−20

v rGa

−40

−60

193.75

193.8

193.85

193.9

193.95

194

194.05

(a) t(s)

1600

1400

(rpm)

1200

mM 1000

ω

&

800

ω mM 600

400

184

186

188

190

192

194

196

198

200

202

204

(b) t(s)

2

1

0

(N.m)

τ LM −1

τ

−2

−3

184

186

188

190

192

194

196

198

200

202

204

(c) t(s)

Fig. 15. PBC-(a) vrGa, vrGb (b) ωmM, ˆ

ωmM (c) ˆ τML.

(76)-(77), is tracking the real speed. Hence, a good estimation of the real IM load torque is

obtained. It has to be noticed that the IM rated torque is 0.7 Nm.

It can be concluded that the PBC provides good practical performance even when the applied

load torque is twice the magnitude of the nominal load torque of the IM.

7.3 PBC + P

1500

(rpm)

ω mM 1000

&

ref

500

ω mM

55

60

65

70

75

80

(a) t(s)

3000

(rpm)

2000

ω mG 1000

55

60

65

70

75

80

(b) t(s)

6

(rad)

4

θ M

&

2

θ G

68.85

68.9

68.95

69

69.05

69.1

(c) t(s)

0.3

0.2

(N.m)

0.1

τ G

0

55

60

65

70

75

80

(d) t(s)

2

1

0

(N.m)

τ Md −1

−2

55

60

65

70

75

80

(e) t(s)

Fig. 16. PBC+P-(a) Regulated Motor speed and its reference. (b)Generator speed. (c) DFIG &

IM rotor position. (d)Generator torque (e) Motor desired torque.

As with the PBC alone, the results obtained with the PBC+P are given in figures 16-19. On the

whole, the system behaviour is the same as the PBC alone. One difference that is noticeable is

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135

15

10

(A)

5

sGb

0

& i

−5

i sGa

−10

−15

68.85

68.9

68.95

69

69.05

69.1

(a) t(s)

15

10

(A)

5

d

sGa

0

& i

−5

i sGa

−10

−15

68.85

68.9

68.95

69

69.05

69.1

(b) t(s)

15

10

(A)

5

d

sGb

0

& i

−5

i sGb

−10

−15

68.85

68.9

68.95

69

69.05

69.1

(c) t(s)

Fig. 17. PBC+P-(a) isGa, isGb (b) id , i

, i

sGa

sGa (c) id

sGb

sGb.

15

10

5

(A)

rGb

0

& i

i rGa

−5

−10

−15

68.85

68.9

68.95

69

69.05

69.1

(a) t(s)

60

40

20

(A)

d

rGa

0

& i

i rGa −20

−40

68.85

68.9

68.95

69

69.05

69.1

69.15

69.2

69.25

69.3

(b) t(s)

60

40

(A)

20

d

rGb

0

& i

i rGb −20

−40

68.85

68.9

68.95

69

69.05

69.1

69.15

69.2

69.25

69.3

(c) t(s)

Fig. 18. PBC+P-(a) irGa, irGb (b) id , i

, i

rGa

rGa (c) id

rGb

rGb.

the small error between the desired stator currents and the real ones thanks to the proportional

controller.

The PBC+P controller exhibits good practical performance but not significantly better than

those obtained with the PBC alone.

7.4 PBC + PI

Again, as for the PBC and the PBC+P controllers, figures 20-23 show the results. It can be

seen in figure 21 that the integral actions on the stator currents do not decrease the error

significantly between the real and desired values in comparison with the results for the PBC+P

136

Electric Machines and Drives

60

40

20

(V)

rGb

0

& v

−20

v rGa

−40

−60

68.85

68.9

68.95

69

69.05

69.1

69.15

69.2

69.25

69.3

(a) t(s)

1600

1400

(rpm)

1200

ω mM 1000

&

800

ω mM

600

400

55

60

65

70

75

80

(b) t(s)

2

1

0

(N.m)

τ LM −1

τ

−2

−3

55

60

65

70

75

80

(c) t(s)

Fig. 19. PBC+P-(a) vrGa, vrGb (b) ωmM, ˆ

ωmM (c) ˆ τML.

1500

(rpm)

ω mM 1000

&

ref

500

ω mM

40

45

50

55

60

65

(a) t(s)

3000

(rpm)

2000

ω mG

1000

40

45

50

55

60

65

(b) t(s)

6

(rad)

4

θ M

&

2

θ G

52.6

52.65

52.7

52.75

52.8

52.85

(c) t(s)

0.3

0.2

(N.m)

0.1

τ G

0

40

45

50

55

60

65

(d) t(s)

2

1

0

(N.m)

τ Md −1

−2

40

45

50

55

60

65

(e) t(s)

Fig. 20. PBC+PI-(a) Regulated Motor speed and its reference. (b)Generator speed. (c) DFIG &

IM rotor position. (d)Generator torque (e) Motor desired torque.

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137

(A)

10

sGb

0

& i

−10

i sGa

52.6

52.65

52.7

52.75

52.8

52.85

(a) t(s)

(A)

10

d

sGa

0

& i

−10

i sGa

52.6

52.65

52.7

52.75

52.8

52.85

(b) t(s)

(A)

10

d

sGb

0

& i

−10

i sGb

52.6

52.65

52.7

52.75

52.8

52.85

(c) t(s)

Fig. 21. PBC+PI-(a) isGa, isGb (b) id , i

, i

sGa

sGa (c) id

sGb

sGb.

(A)

10

rGb

0

& i

−10

i rGa

52.6

52.65

52.7

52.75

52.8

52.85

(a) t(s)

50

(A)

d

rGa

0

& i

i rGa −50

52.6

52.65

52.7

52.75

52.8

52.85

52.9

52.95

53

(b) t(s)

50

(A)

d

rGb

0

& i

i rGb −50

52.6

52.65

52.7

52.75

52.8

52.85

52.9

52.95

53

(c) t(s)

Fig. 22. PBC+PI-(a) irGa, irGb (b) id , i

, i

rGa

rGa (c) id

rGb

rGb.

controller (see fig. 17). This is due to the fact that the reference values are sinusoidal and that

the bandwidth of the PI controllers cannot be increased sufficiently experimentally.

It can be concluded that the PI action on the stator currents does not improve significantly the

performance obtained with the PBC+P controller.

7.5 PI

The PI control law (with Kp and Ki are proportional and integral gains) is given below:

BvrG = B Kp( isG − id ) +

)

sG

Ki( isG − idsG

(78)

138

Electric Machines and Drives

(V)

50

rGb

0

& v

−50

v rGa

52.6

52.65

52.7

52.75

52.8

52.85

52.9

52.95

53

(a) t(s)

(rpm)

1500

ω mM 1000

&

500

ω mM

40

45

50

55

60

65

(b) t(s)

2

0

(N.m)

τ τ LM −2

40

45

50

55

60

65

(c) t(s)

Fig. 23. PBC+PI-(a) vrGa, vrGb (b) ωmM, ˆ

ωmM (c) ˆ τML.

)m

(rp

1500

M

ω m 1000

&

ref

M

500

230

235

240

245

250

255

ω m

2500

t(s)

)m 2000

(rp

1500

G 1000

ω m 500

230

235

240

245

250

255

t(s)

6

(rad)

4

θ M 2

& θ G

241.35

241.4

241.45

241.5

241.55

t(s)

)

0

m

(N.

−0.2

τ G −0.4

230

235

240

245

250

255

t(s)

)m 2

0

(N.

−2

τ Md

230

235

240

245

250

255

t(s)

Fig. 24. PI-(a) Regulated Motor speed and its reference. (b)Generator speed. (c) DFIG & IM

rotor position. (d) Generator torque (e) Motor desired torque.

From Dynamic Modeling to Experimentation of

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139

10

(A)

5

sGb

0

& i

−5

i sGa

−10

241.35

241.4

241.45

241.5

241.55

t(s)

10

(A)

5

d

sGa

0

& i

−5

i sGa

−10

241.35

241.4

241.45

241.5

241.55

t(s)

10

(A)