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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.