1. Synchronous Generator
SMJE 2103
Synchronous Generator

2. Synchronous Generator
Scope of discussion
Construction
Rotation speed
Generated voltage
Equivalent circuit
Power and Torque
Testing
Parallel operation
Rating

3. Synchronous Generator -construction-

4. Synchronous Generator -speed of rotation-
The electrical frequency is synchronized with the mechanical rate of rotation
Relationship between magnetic field speed and electrical frequency,

5. Synchronous Generator -generated voltage-
Induced voltage,

6. Synchronous Generator -equivalent circuit-
There are some factors that affected in forming of an equivalent circuit:
Armature reaction
Self inductance of the armature coil
Resistance of the armature coil
The effect of salient pole rotor shapes

7. Armature Reaction

8. Synchronous Generator -equivalent circuit-

9. Synchronous Generator -equivalent circuit-

10. Full equivalent circuit

11. Synchronous Generator -power and torque-

12. Synchronous Generator -power and torque-

13. Synchronous Generator -power and torque-
- RA assumed to be zero
 Torque angle
Maximum torque due to max power when sin  is 1

14. Synchronous Generator -power and torque-
Basic torque equation:
From power expression Pout = Pconv = indm

15. Synchronous Generator -testing-
Purpose of test is to determine these parameters:
Field current and flux relationship
Synchronous reactance
Armature resistance
Open circuit and short circuit tests should be performed in order to get the purpose.

16. Synchronous Generator -testing (open circuit)-
Procedures:
Generators is rotated at the rated speed
No load is connected at the terminals
Field current is increased from 0 to maximum
Record values of the terminal voltage and field current value

17. Synchronous Generator -testing (open circuit)-
The iron saturated, mmf getting slow down due to increasing reluctance of the iron
IA = 0, so EA = V, possible to plot EA or VT vs IF graph. It is possible to find internal generated voltage for any given field current

18. Synchronous Generator -testing (short circuit)-
Procedures of short circuit test:
Generator is rotated at rated speed
Adjust field current to 0
Short circuit the terminals
Measure armature current or line current as the field current is increased.

19. Synchronous Generator -testing (short circuit)-
The net magnetic field is very small, the iron is not saturated, so the relationship is linear

20. Synchronous Generator -testing (short circuit)-
From the both tests. EA from OCC while IA from SCC

21. Synchronous Generator -parallel operation-
Reasons for operating in parallel:
Handling larger loads.
Maintenance can be done w/t power disruption.
Increasing system reliability.
Increased efficiency.

22. Synchronous Generator -parallel operation-
Condition required:
RMS line voltage must be equal.
Both have same phase sequence.
Output phase angles are same.
Must have a slightly higher frequency for new generator. It will change slowly.

23. Synchronous Generator -ratings-
Frequency rating: the frequency at the system.
Voltage rating: voltage generated that depend on flux and speed.
Apparent power rating: maximum power with maximum armature current.
Power factor rating: