1. Synchronizing a) Set up the circuit shown in Fig. 1. Note the cumulative
connection of the series field of the. DC motor. The synchronous generator
should be ...
ECE 420 Spring 2011 – on-campus
Experiment No. 2 Synchronous Machines
Experiment No. 2 Synchronous Generator Objective The objectives of this experiment are to learn to synchronize a synchronous generator to a large stable system and to demonstrate the operating characteristics of a synchronous generator when delivering power to a large stable system. Apparatus 1. 2 test tables 2. DC motor-synchronous generator set 3. 1 5 A Kenwood DC power supply 4. 1 0-150 V DC voltmeter 5. 2 5 A field rheostats 6. 1 0-100 A DC ammeter 7. 1 current transformer 8. 1 0-5 A AC ammeter 9. 1 0-300/150 V AC voltmeter 10. 1 wattmeter 11. 1 synchronous machine tach. 12. Strobe
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ECE 420 Spring 2011 – on-campus
Experiment No. 2 Synchronous Machines
Procedure 1. Synchronizing a) Set up the circuit shown in Fig. 1. Note the cumulative connection of the series field of the DC motor. The synchronous generator should be connected for 220 V 3-φ wye operation. Open all line switches on the test table connected to the synchronous generator and Avista. Start the dc motor. Adjust IFmotor until the speed of the dc motor-synchronous generator set (n) is nearly 1200 rpm. Note: Subscript “AV” is used to represent Avista side quantities, subscript “gen” is used to represent generator side quantities and subscript “motor” is used to represent quantities of DC motor. b) Measure the line-to-line voltage V1-2AV. Adjust IFgen until V1-2gen equals V1-2AV. Close the line switch for line 3 on the test table connected to the synchronous generator. Close the switches of the synchronizing lights on lines 1 and 2. Note: The line switch and the switches of synchronizing lights are different. If the lights in lines 1 and 2 are not blinking on and off simultaneously, go to step c. If the lights in lines 1 and 2 are blinking on and off simultaneously, go to step d. c) Open the switches for the synchronizing lights. Then open the switches for the generator field current, line 3 and main breaker. Once all the line switches are open, swap leads 1 and 2 on the Avista source side of the table. Repeat step b. d) Adjust IFmotor until the synchronizing lights are blinking on and off as slowly as possible. While the synchronizing lights in lines 1 and 2 are completely dark close the line switches for these two lines simultaneously. Note: The middle of the dark period is the zero difference point. The incoming machine, the lab machine, should be the faster unit so it should pick up a load upon synchronizing. If this is the case, the dc motor current will increase upon synchronizing. After the line switches are successfully closed, open the switches for the synchronizing lights. Check for balanced 3-φ AC voltages and currents. Check to see if the dc motor current has increased. Measure and record IFmotor, Imotor, Vmotor, VFgen, IFgen, VLLgen, ILgen, PWM1 and PWM2. 2.
Strobe and Tick Marks Record the angle using the strobe and tick marks (refer Fig.2). The torque angle can be determined from changes from a known reference torque angle δref in mechanical degrees. The value of δ in mechanical degrees is then found by adding or subtracting the reading from δref. The value of δ in electrical degrees is then found by multiplying δ in mechanical degrees by P/2 where P is the number of synchronous generator poles (6 poles).
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ECE 420 Spring 2011 – on-campus
Experiment No. 2 Synchronous Machines
3. Operating Conditions I.
Synchronous Condenser
a) Slowly decrease IFgen as far as the kenwood supply will allow or until I1gen equals rated line current. Measure and record IFmotor, Imotor, Vmotor, VFgen, IFgen, VLLgen, ILgen, PWM1, PWM2 and δ using the strobe and tick marks. b) Slowly increase IFgen until I1gen is at a minimum (close to zero) and δ is zero. c) Slowly increase IFgen until I1gen equals rated line current. Measure and record the same quantities as in part a. d) Slowly decrease IFgen until I1gen is at a minimum (close to zero) and δ is zero. II.
Synchronous Generator
a) Slowly decrease IFmotor until I1gen equals half the rated current. At this point the DC machine is motoring and the synchronous machine is delivering real power to Avista utility. Measure and record IFmotor, Imotor, Vmotor, VFgen, IFgen, VLLgen, ILgen, PWM1, PWM2 and δ using the strobe and tick marks. b) Slowly decrease IFgen as far as the kenwood supply will allow or until I1gen equals rated line current. Measure and record the same quantities as in part a. c) Slowly increase IFgen until I1gen is at a minimum (not zero). d) Slowly increase IFgen as far as the kenwood supply will allow or until I1gen equals rated line current. Measure and record the same quantities as in part a. e) Slowly decrease IFgen until I1gen is at a minimum (not zero). III.
Synchronous Motor
a) Slowly increase IFmotor until I1gen equals half the rated current (calculate rated current before the experiment is started). At this point the DC machine is generating and the synchronous machine is consuming real power from Avista utility. Measure and record Imotor, Vmotor, VLLgen, ILgen, IFgen, and P3-∅ and δ using the strobe and tick marks. b) Slowly decrease IFgen as far as the kenwood supply will allow or until I1gen equals rated line current. Measure and record the same quantities as in part a. c) Slowly increase IFgen until I1gen is at a minimum (not zero).
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ECE 420 Spring 2011 – on-campus
Experiment No. 2 Synchronous Machines
d) Slowly increase IFgen as far as the field rheostat will allow or until I1gen equals rated line current. Measure and record the same quantities as in part a. Report
1. Calculate the power factor of the synchronous machine for the operating conditions of parts Ia, Ic, IIb, IId and IIIb, IIId of the procedure section of this handout. Also state whether the machine is operating at lagging or leading power factor and supplying or consuming reactive power from the values of PMW1 and PMW2. 2. Use Figures 3 and 4 for this part. Note: Make sure to use proper conventions for generator and motor operation. For the operating conditions of parts Ia, Ic, IIb, IId and IIIb, IIId of the procedure section of this handout: (a) Calculate Ef. (b) Draw a phasor diagram showing Ef, V1, I1, jI1Xd (assume it to be j3.6ohm), δelec (load angle or torque angle) and θ (power factor angle). Assume the stator resistance per phase is 0.4ohm. Use your calculated value for Ef. Use V1∠0 as your reference.
δ elec = δ mech ⋅
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P 2
ECE 420 Spring 2011 – on-campus
Experiment No. 2 Synchronous Machines
Tabular Form: Wattmeter Ratio (WMR ) = and Current Transformer Ratio (CTR ) =
Synchronizing: a)
S.No
DC Side measurements: IFmotor
I motor
Vmotor
V Fgen
IFgen
A
A
V
V
A
1. AC Side measurements: S.No V 1-2gen V 2-3gen V 3-1gen V
V
V
WMR =
CTR =
I1gen
I2gen
I3gen
PWM1
PWM2
δmech
δElec
A
A
A
Watt
Watt
Deg
Deg
1.
I. Synchronous Condensor: a)
S.No
DC Side measurements: Consuming VAR’s IFmotor
I motor
Vmotor
V Fgen
IFgen
A
A
V
V
A
1. AC Side measurements: Consuming VAR’s V 1-2gen V 2-3gen V 3-1gen
WMR =
CTR =
I1gen
I2gen
I3gen
PWM1
PWM2
δmech
δElec
A
A
A
Watt
Watt
Deg
Deg
S.No V
V
V
1. c) DC Side measurements: Supplying VAR’s S.No IFmotor I motor V Fgen Vmotor A
V
A
V
IFgen A
1. AC Side measurements: Supplying VAR’s S.No V 1-2gen V 2-3gen V 3-1gen V
V
V
WMR =
CTR =
I1gen
I2gen
I3gen
PWM1
PWM2
δmech
δElec
A
A
A
Watt
Watt
Deg
Deg
1.
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ECE 420 Spring 2011 – on-campus
Experiment No. 2 Synchronous Machines
II. Synchronous Generator: a) DC Side measurements: Supply Active Power (No VAR’s) S.No IFmotor I motor V Fgen IFgen Vmotor A
V
A
V
A
1. AC Side measurements: Supply Active Power (No VAR’s) S.No V 1-2gen V 2-3gen V 3-1gen V
V
V
WMR =
I1gen
I2gen
I3gen
PWM1
PWM2
δmech
δElec
A
A
A
Watt
Watt
Deg
Deg
CTR =
1. b) DC Side measurements: Supply Active Power and Consuming VAR’s S.No IFmotor I motor V Fgen IFgen Vmotor A
V
A
V
A
1. AC Side measurements: Supply Active Power and Consuming VAR’s S.No V 1-2gen V 2-3gen V 3-1gen V
V
V
WMR =
I1gen
I2gen
I3gen
PWM1
PWM2
δmech
δElec
A
A
A
Watt
Watt
Deg
Deg
CTR =
1. d) DC Side measurements: Supply Active Power and Supplying VAR’s S.No IFmotor I motor Vmotor V Fgen IFgen A
V
A
V
A
1. AC Side measurements: Supply Active Power and Supplying VAR’s S.No V 1-2gen V 2-3gen V 3-1gen V
V
V
WMR =
I1gen
I2gen
I3gen
PWM1
PWM2
δmech
δElec
A
A
A
Watt
Watt
Deg
Deg
1.
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CTR =
ECE 420 Spring 2011 – on-campus
Experiment No. 2 Synchronous Machines
III. Synchronous Motor: a) DC Side measurements: Consume Active Power (No VAR’s) S.No IFmotor I motor V Fgen IFgen Vmotor A
V
A
V
A
1. AC Side measurements: Consume Active Power (No VAR’s) S.No V 1-2gen V 2-3gen V 3-1gen V
V
V
WMR =
I1gen
I2gen
I3gen
PWM1
PWM2
δmech
δElec
A
A
A
Watt
Watt
Deg
Deg
CTR =
1.
b) DC Side measurements: Consume Active Power and Consume VAR’s S.No IFmotor I motor V Fgen IFgen Vmotor A
V
A
V
A
1. AC Side measurements: Consume Active Power and Consume VAR’s S.No V 1-2gen V 2-3gen V 3-1gen V
V
V
WMR =
I1gen
I2gen
I3gen
PWM1
PWM2
δmech
δElec
A
A
A
Watt
Watt
Deg
Deg
CTR =
1.
d) DC Side measurements: Consume Active Power and Supply VAR’s I motor S.No IFmotor V Fgen IFgen Vmotor A
V
A
V
A
1. AC Side measurements: Consume Active Power and Supply VAR’s S.No V 1-2gen V 2-3gen V 3-1gen V
V
V
WMR =
I1gen
I2gen
I3gen
PWM1
PWM2
δmech
δElec
A
A
A
Watt
Watt
Deg
Deg
1.
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CTR =
ECE 420 Spring 2011 – on-campus
Experiment No. 2 Synchronous Machines
Test Table 1
Test Table 2 Series Field
L1
DC Motor
AC Generator
I1 gen
A F
V1-3
115V DC
V1-2 gen Shunt Field
L2
IF gen
I3 motor
115V DC
Fig.1 Circuit Schematic for Synchronous Generator Connected to Infinite Bus
DOR – Direction of Rotation of S/G
Rotor Red Mark Reference point for measurement of δmech
Direction of measurement of δ mech
Fig.2 Load angle Measurement
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3 Phase Avista utility supply
ECE 420 Spring 2011 – on-campus
Experiment No. 2 Synchronous Machines
Fig.3 Generator connected to infinite bus
Fig.4 Phasor diagram for system shown in Fig.3
Where V1 is line to neutral terminal voltage (take the average of all the three phases). Ef is induced emf. I1 is line current (take the average of all the three phases). Xd is the direct axis reactance of synchronous machine. θ is the PF angle calculated using the two wattmeter method. δelec is the load angle or torque angle as shown in figure above. Ideally the calculated value of load angle should be equal to the measured value.
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