Synchronous Generator SMJE 2103 Synchronous Generator
Synchronous Generator Scope of discussion Construction Rotation speed Generated voltage Equivalent circuit Power and Torque Testing Parallel operation Rating
Synchronous Generator -construction-
Synchronous Generator -speed of rotation- The electrical frequency is synchronized with the mechanical rate of rotation Relationship between magnetic field speed and electrical frequency,
Synchronous Generator -generated voltage- Induced voltage,
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
Armature Reaction
Synchronous Generator -equivalent circuit-
Synchronous Generator -equivalent circuit-
Full equivalent circuit
Synchronous Generator -power and torque-
Synchronous Generator -power and torque-
Synchronous Generator -power and torque- - RA assumed to be zero Torque angle Maximum torque due to max power when sin is 1
Synchronous Generator -power and torque- Basic torque equation: From power expression Pout = Pconv = indm
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.
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
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
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.
Synchronous Generator -testing (short circuit)- The net magnetic field is very small, the iron is not saturated, so the relationship is linear
Synchronous Generator -testing (short circuit)- From the both tests. EA from OCC while IA from SCC
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.
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.
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: