When we connect a generator to a grid it would start to be synchronized with the grid electrical frequency and if two generators have the same grid and same poles number then they would have same rotational speed.
One of the reasons why generators lock to one speed are the dampers (q-axis dampers, d-axis dampers or both), but even if dampers do not exist the generators still synchronized under normal operating conditions.
In other words what would happen,and cause re-synchronization, if a generator speed exceeded or dropped below the synchronization speed ?
One of the reasons why generators lock to one speed are the dampers (q-axis dampers, d-axis dampers or both), but even if dampers do not exist the generators still synchronized under normal operating conditions.
In other words what would happen,and cause re-synchronization, if a generator speed exceeded or dropped below the synchronization speed ?
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I assume we are talking about 3 phase alternators here.
A 3 phase AC alternator is also a 3 phase motor. If the prime mover is not turning the alternator fast enough, the alternator becomes a motor and will draw power from the grid to run at synchronous speed, driving the prime mover faster than it might otherwise turn. If the prime mover attempts to drive the alternator faster than synchronous speed of the grid, power delivered to the grid will tend to lead the phase of the grid and greater power will be delivered and the prime mover will experience increasing mechanical load. If the prime mover is really pushing hard, the circuit breakers should disconnect to protect the alternator. Also if the prime mover looses power, the alternator becomes a motor and drives it until the circuit breakers trip due to excessive current.
A 3 phase AC alternator is also a 3 phase motor. If the prime mover is not turning the alternator fast enough, the alternator becomes a motor and will draw power from the grid to run at synchronous speed, driving the prime mover faster than it might otherwise turn. If the prime mover attempts to drive the alternator faster than synchronous speed of the grid, power delivered to the grid will tend to lead the phase of the grid and greater power will be delivered and the prime mover will experience increasing mechanical load. If the prime mover is really pushing hard, the circuit breakers should disconnect to protect the alternator. Also if the prime mover looses power, the alternator becomes a motor and drives it until the circuit breakers trip due to excessive current.