TurbineGen
Electrical
- Mar 1, 2007
- 489
Can anyone comment about ways to control transients in a potential transformer circuit without causing a phase shift?
Here's my scenario. We have a 30 MW generator that we synchronize online by using a signal from a PT to both determine it's speed and phase angle. This unit is a peaking unit which starts and stops daily. The problem is that at approimately 15 hz (electrical frequency) a few breakers close and cause false readings by our control system, causing speed reading in excess of 100% synchronous speed. Obviously this is a false reading, and it tends to last for three to five seconds (not 3-5 cycles). One issue is that at 95% speed we close the exciter breaker and start adjusting our controls to prepare for synchronization. Another problem is that as the transient falls off, the control reads that the generator is rapidly slowing down, which it isn't, and will trip.
Since the PT is used to obtain the phase angle of the generator for synchronization, a phase shift in this signal could be catastrophic to the generator. How can I control this transient without a phase shift on the PT signal? The signal must usable and accurate from 5hz up to 65 hz. Any assistance with this problem is greatly appreciated.
Thanks in advance.
Quote: If it is broken, fix it. If it isn't broken, I'll soon fix that.
Here's my scenario. We have a 30 MW generator that we synchronize online by using a signal from a PT to both determine it's speed and phase angle. This unit is a peaking unit which starts and stops daily. The problem is that at approimately 15 hz (electrical frequency) a few breakers close and cause false readings by our control system, causing speed reading in excess of 100% synchronous speed. Obviously this is a false reading, and it tends to last for three to five seconds (not 3-5 cycles). One issue is that at 95% speed we close the exciter breaker and start adjusting our controls to prepare for synchronization. Another problem is that as the transient falls off, the control reads that the generator is rapidly slowing down, which it isn't, and will trip.
Since the PT is used to obtain the phase angle of the generator for synchronization, a phase shift in this signal could be catastrophic to the generator. How can I control this transient without a phase shift on the PT signal? The signal must usable and accurate from 5hz up to 65 hz. Any assistance with this problem is greatly appreciated.
Thanks in advance.
Quote: If it is broken, fix it. If it isn't broken, I'll soon fix that.