Experiment No. 2. Synchronous Generator

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Reynard Bishop
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1 Objective Experiment No. 2 Synchronous Generator 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. pparatus 2 test tables 2. DC motor-synchronous generator set Kenwood DC power supply DC voltmeter field rheostats DC ammeter 7. 1 current transformer C ammeter /150 C voltmeter wattmeter 1 1 synchronous machine tach. 12. Strobe 1/9

2 Procedure Synchronizing a) Set up the circuit shown in Fig. Note the cumulative connection of the series field of the DC motor. The synchronous generator should be connected for φ wye operation. Open all line switches on the test table connected to the synchronous generator and vista. Start the dc motor. djust until the speed of the dc motor-synchronous generator set (n) is nearly 1200 rpm. Note: Subscript is used to represent vista 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 1-2. djust until 1-2gen equals 1-2. 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 vista source side of the table. Repeat step b. d) djust 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. fter the line switches are successfully closed, open the switches for the synchronizing lights. Check for balanced 3-φ C voltages and currents. Check to see if the dc motor current has increased. Measure and record,, motor, Fgen,, LLgen, I Lgen, P WM1 and P WM2. 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 δ ref in mechanical degrees. The value of δ in mechanical degrees is then found by adding or subtracting the reading from δ ref. 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). 2/9

3 3. Operating Conditions I. Synchronous Condenser a) Slowly decrease as far as the kenwood supply will allow or until I 1gen equals rated line current. Measure and record,, motor, Fgen,, LLgen, I Lgen, P WM1, P WM2 and δ using the strobe and tick marks. b) Slowly increase until I 1gen is at a minimum (close to zero) and δ is zero. c) Slowly increase until I 1gen equals rated line current. Measure and record the same quantities as in part a. d) Slowly decrease until I 1gen is at a minimum (close to zero) and δ is zero. II. Synchronous Generator a) Slowly decrease until I 1gen equals half the rated current. t this point the DC machine is motoring and the synchronous machine is delivering real power to vista utility. Measure and record,, motor, Fgen,, LLgen, I Lgen, P WM1, P WM2 and δ using the strobe and tick marks. b) Slowly decrease as far as the kenwood supply will allow or until I 1gen equals rated line current. Measure and record the same quantities as in part a. c) Slowly increase until I 1gen is at a minimum (not zero). d) Slowly increase as far as the kenwood supply will allow or until I 1gen equals rated line current. Measure and record the same quantities as in part a. e) Slowly decrease until I 1gen is at a minimum (not zero). III. Synchronous Motor a) Slowly increase until I 1gen equals half the rated current (calculate rated current before the experiment is started). t this point the DC machine is generating and the synchronous machine is consuming real power from vista utility. Measure and record, motor, LLgen, I Lgen,, and P 3- and δ using the strobe and tick marks. b) Slowly decrease as far as the kenwood supply will allow or until I 1gen equals rated line current. Measure and record the same quantities as in part a. c) Slowly increase until I 1gen is at a minimum (not zero). 3/9

4 d) Slowly increase as far as the field rheostat will allow or until I 1gen equals rated line current. Measure and record the same quantities as in part a. Report 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. lso state whether the machine is operating at lagging or leading power factor and supplying or consuming reactive power from the values of P MW1 and P MW2. 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 E f. (b) Draw a phasor diagram showing E f, 1, I 1, ji 1 X d (assume it to be j3.6ohm), δ elec (load angle or torque angle) and θ (power factor angle). ssume the stator resistance per phase is 0.4ohm. Use your calculated value for E f. Use 1 0 as your reference. δ elec = δ mech P 2 4/9

5 Tabular Form: meter Ratio (WMR ) = and Current Transformer Ratio (CTR ) = Synchronizing: a) DC Side measurements: motor Fgen C Side measurements: WMR = CTR = 1-2gen 2-3gen 3-1gen I 1gen I 2gen I 3gen P WM1 P WM2 I. Synchronous Condensor: a) DC Side measurements: Consuming R s motor Fgen C Side measurements: Consuming R s WMR = CTR = 1-2gen 2-3gen 3-1gen I 1gen I 2gen I 3gen P WM1 P WM2 c) DC Side measurements: Supplying R s motor Fgen C Side measurements: Supplying R s WMR = CTR = 1-2gen 2-3gen 3-1gen I 1gen I 2gen I 3gen P WM1 P WM2 5/9

6 II. Synchronous Generator: a) DC Side measurements: Supply ctive Power (No R s) motor Fgen C Side measurements: Supply ctive Power (No R s) WMR = CTR = 1-2gen 2-3gen 3-1gen I 1gen I 2gen I 3gen P WM1 P WM2 b) DC Side measurements: Supply ctive Power and Consuming R s motor Fgen C Side measurements: Supply ctive Power and Consuming R s WMR = CTR = 1-2gen 2-3gen 3-1gen I 1gen I 2gen I 3gen P WM1 P WM2 d) DC Side measurements: Supply ctive Power and Supplying R s motor Fgen C Side measurements: Supply ctive Power and Supplying R s WMR = CTR = 1-2gen 2-3gen 3-1gen I 1gen I 2gen I 3gen P WM1 P WM2 6/9

7 III. Synchronous Motor: a) DC Side measurements: Consume ctive Power (No R s) motor Fgen C Side measurements: Consume ctive Power (No R s) WMR = CTR = 1-2gen 2-3gen 3-1gen I 1gen I 2gen I 3gen P WM1 P WM2 b) DC Side measurements: Consume ctive Power and Consume R s motor Fgen C Side measurements: Consume ctive Power and Consume R s WMR = CTR = 1-2gen 2-3gen 3-1gen I 1gen I 2gen I 3gen P WM1 P WM2 d) DC Side measurements: Consume ctive Power and Supply R s motor Fgen C Side measurements: Consume ctive Power and Supply R s WMR = CTR = 1-2gen 2-3gen 3-1gen I 1gen I 2gen I 3gen P WM1 P WM2 7/9

8 Test Table 1 Test Table 2 Series Field DC Motor C Generator I 1 gen 115 DC L 1 F 1-3 Shunt Field 1-2 gen 3 Phase vista utility supply L 2 I F gen I 3 motor 115 DC Fig.1 Circuit Schematic for Synchronous Generator Connected to Infinite Bus DOR Direction of Rotation of S/G Rotor Reference point for measurement of Direction of measurement of Red Mark Fig.2 Load angle Measurement 8/9

9 Fig.3 Generator connected to infinite bus Where Fig.4 Phasor diagram for system shown in Fig.3 1 is line to neutral terminal voltage (take the average of all the three phases). E f is induced emf. I 1 is line current (take the average of all the three phases). X d is the direct axis reactance of synchronous machine. θ is the PF angle calculated using the two wattmeter method. δ elec 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. 9/9

EE 340L EXPERIMENT # 3 SYNCHRONOUS GENERATORS

EE 340L EXPERIMENT # 3 SYNCHRONOUS GENERATORS A. EQUIVALENT CIRCUIT PARAMETERS A.1. OPEN CIRCUIT TEST (a) Mechanically couple the generator with a shunt-excited DC motor as shown in figure 4(a). (b) With