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INDUCTION GENARATOR

Instructed By : H.A. De Silva

Name : Wijendrasiri H.K.G.M

Index Number : 090570 C

Department : EE

Date Of Performance : 30/08/2011

Date Of Submission : 14/09/2011


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Calculations :

Part a:

i) Voltage Vs Magnetizing CurrentMagnetizing Current(A) Voltage(V)

2.1 2352.2 240

2.35 246

2.8 270

3.4 284


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200

220

240

260

280

300

1.5 2.5 3.5

Voltage/V

Magnatizing Current/A

Voltage Vs Magnetizing Current


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ii) Voltage Vs CapacitanceCapacitance(F) Voltage(V)

60 235

62 240

65 246

70 27075 284


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0

50

100

150

200

250

300

0 20 40 60 80 100

Voltage/V

Capacitance/106 F

Voltage Vs Capacitance


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y The capacitance required to obtain the rated voltage of 240V = 62 Fy At 240V the Im= 2.2A.But Steady state Im = Ic.

C =

C =

C = 29.18F

Part b:

i) Voltage Vs SpeedSpeed(rpm) Voltage(V)

2400 200

2460 220

2512 240

2590 260

2652 280


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150

170

190

210

230

250

270

290

2200 2300 2400 2500 2600 2700

Voltage/V

Speed/rpm

Voltage Vs Speed


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i) Frequency Vs SpeedSpeed(rpm) Frequency(Hz)

2400 39.4

2460 40.8

2512 41.7

2590 432652 44


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39

40

41

42

43

44

45

2350 2400 2450 2500 2550 2600 2650 2700

Frequency/Hz

Speed/rpm

Frequency Vs Speed


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ii) Magnetizing Current Vs SpeedSpeed(rpm) Magnetizing Current(A)

2400 1.7

2460 1.95

2512 2.2

2590 2.45

2652 2.7


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1

1.2

1.4

1.6

1.8

2

2.2

2.4

2.6

2.8

2350 2400 2450 2500 2550 2600 2650 2700

MagnatizingCurrent/A

Speed/rpm

Magnetizing Current Vs Speed


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Part c :

i) Voltage Vs Load Current(With speed regulation)Load Current(A) Voltage(V)

0 284

0.5 2800.96 268

1.4 258

1.76 246

Part d :

i) Voltage Vs Load Current(Without speed regulation)Load Current(A) Voltage(V)

0 284

0.48 270

0.92 256

1.3 240

1.64 226


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200

210

220

230

240

250

260

270

280

290

0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2

Voltage/V

Load Current/A

Voltage Vs Load Current


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Part c :

ii) Frequency Vs Load Current(With speed regulation)Load Current(A) Frequency(Hz)

0 41.4

0.5 41.3

0.96 40.8

1.4 40.6

1.76 40.3

Part d :

ii) Frequency Vs Load Current(Without speed regulation)

Load Current(A) Frequency(Hz)

0 41.5

0.48 40.7

0.92 40

1.3 39.6

1.64 39.2


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39

39.5

40

40.5

41

41.5

42

0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2

Frequency/Hz

Load Current/A

Frequency Vs Load Current


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Part c :

iii) Generator Current Vs Load Current

Load Current(A) Generator Current(A)

0 3.20.5 3.2

0.96 3.15

1.4 3.2

1.76 3.25


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3.1

3.3

0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2

GenaratorCurrent/A

Load Current/A

Generator Current Vs Load Current


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Part d :

iii) TorqueVs Speed

Speed(rpm) Torque(Nm)

2500 1.62475 2.5

2454 3.2

2440 3.7

2434 4


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1

1.5

2

2.5

3

3.5

4

4.5

2430 2440 2450 2460 2470 2480 2490 2500 2510

Torque/Nm

Speed/rpm

Torque Vs Speed


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2. Grid Connected Induction Generator

i) Power Output Vs Speed

Speed(rpm) Power Output(W)

3025 80

3043 220

3060 3403075 400

3095 520


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0

100

200

300

400

500

600

3020 3030 3040 3050 3060 3070 3080 3090 3100

PowerOutput/W

Speed/rpm

Power Output Vs Speed


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ii) Line Current Vs SpeedSpeed(rpm) Line Current(A)

3025 1.5

3043 1.6

3060 1.8

3075 1.93095 2.25


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1

1.2

1.4

1.6

1.8

2

2.2

2.4

3000 3020 3040 3060 3080 3100

LineCurrent/A

Speed/rpm

Line Current Vs Speed


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iii) Efficiency Vs Speed

Calculation :

= 3025 rpm = 1.6 NmOutput Power (wattmeter reading) = 220 W

=

= 15.8 %

Speed(rpm) Efficiency(%)

3025 15.8

3043 32.883060 40.81

3075 44.36

3095 48.62


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iv) PowerFactorVs SpeedCalculation :

Wattmeter reading = 220 W

Apparent power = V =324W

= 0.247

Speed(rpm) PowerFactor

3025 0.2473043 0.637

3060 0.874

3075 0.966


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0

0.2

0.4

0.6

0.8

1

1.2

3020 3030 3040 3050 3060 3070 3080

PowerFactor

Speed/rpm

Power Factor Vs Speed


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Discussion :

1. Why the no-load test was designed to result in a lower frequency than the rated frequency of 50Hz ?When the load is absence the output active power of the generator is at its minimum value. Thus

the slip of the generator is also at a very low value, close to zero. So the generator will reach its rated

voltage before 50Hz occurs. If the generator works under this condition continuously it will tend to a

voltage higher than it. To work under rated voltage the generator should be worked below 50Hz at no

load. Because when load is added to a generator its slip increases causing frequency to drop .

2. The cause of variation of the voltage and the current waveforms of the generator when loading.Voltage Waveform

When load is increased on a generator if the speed is not regulated, its frequency will decrease.

So the voltage waveform will expand in the time axis as the rotor speed reduces.

Current Waveform

It is general that, if the load becomes very high more power it draws from the generator. So

when load on is increasing the amplitude of the current waveform will increase and besides that it will

expand along time axis too.

3. The importance of induction generators both self-excited and grid connected in power generation of SriLanka

Self Excited

Owing to its many advantages, th

e self excited induction generatorh

as emerged from among th

ewell known generators as a suitable candidate to be driven by wind turbine. Some of its advantages are

small size and weight, robust construction, absence of separate source for excitation and reducedmaintenance cost. When the induction generator is connected to an infinite power net, the analysis

becomes simple, since the voltage and frequency are determined by the driving network. Self excitedinduction generators are good mainly used in wind powered electric generation application especially in

remote areas. An external power supply is not needed to produce the magnetic field. Therefore inremote areas of Sri Lanka this is the ideal solution for need of electricity. They do not inherit the

weakness of permanent magnet generators where the magnetic field deteriorates as time elapses causingthe generated voltage to drop by big numbers. These are gradually replacing synchronous alternators in

standalone power generation due to low unit cost and ease of maintenance and operation. Theysatisfactorily cope with dynamic loads under low speed operation.

Grid Connected

Grid connected systems are normally between 10kW and 100kW. The power must be

conditioned using an inverter before fed to the grid. Self-commutated inverters, due to their own

oscillators need a reference from the utility grid to hold synchronization. When linked with a battery

they may become part of an uninterrupted power supply, which is important in the event of a blackout.

Line-commutated inverters are actuated by utility- line power. Both types of inverters produce sine-

wave grid quality output, but act differently in the event of a grid blackout. Line commutated version

may fail to operate in blackouts.


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4. Description of plotted graphsa) Self Excited Induction Generator

a. No Load characteristics for varying capacitance and constant prime mover speed.i. Line Voltage Vs Magnetizing Current

The curve gives a parabolic shape. As Magnetizing current increases the gradient of

Voltage curve decreases .

ii. Line Voltage Vs CapacitanceLine voltage increases with Capacitance closely in linear manner .

b. No Load characteristic for varying prime mover speed and constant capacitance.i. Voltage Vs Speed

Voltage increases wit

hth

e Speed nearly in a linear manner

ii. Frequency Vs SpeedFrequency increases with the Speed closely in linear manner.

iii. Magnetizing Current Vs SpeedMagnetizing Current also increases with the Speed in a linear manner.

c. Performance of loaded generator with constant speed.i. Voltage Vs Load Current

Voltage decreases as Load Current increases by giving a curve of parabolic

shape.

ii. Frequency Vs Load CurrentFrequency decreases when the load current increases , but it does not give a linear

combination .

iii. Generator Current Vs Load CurrentLoad current increases with generator current.


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d. Performance of the loaded generator without speed regulation.

i. Voltage Vs Load CurrentVoltage decreases as Load Current increases by giving a curve of parabolic

shape.

ii. Frequency Vs Load CurrentFrequency decreases when the load current increases , but it does not give a linear

combination .

iii. Torque vs. SpeedTorque decreases as the Speed rises in a linear manner.

b) Grid connected Induction Generatori. Power Output Vs SpeedPower Output is increasing with Speed somewhat linearly .

ii. Line Current Vs SpeedLine Current increases with Speed by giving a parabolic shape ,the

gradient of the graph is increasing .

iii. Efficiency Vs SpeedEfficiency increases with as Speed increases

iv. PowerFactorVs SpeedPowerFactor is increasing with Speed giving a parabolic shape ,and gradient of

the graph is increasing.

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