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I am working on my thesis, and one of the item I am covering is the challenge of detecting a loss of sensing voltage to the AVR when the network is weak.
My principal (which is also my employer as I am both a student and a service engineer) is in the business of delivering diesel electric power systems for rigs and vessels with a high need for redundancy (DP class 2 and above).
The main challenge with detecting a loss of sensing voltage is that class requirements does not allow us to solely rely on the AVR itself to report about the failure. It also has a very dangerous impact on the power system as all of the ship's propulsion is powered by frequency converters which *will* trip if the voltage rises above a certain limit. This will render the vessel inoperable which can be very serious.
Some vendors has simply installed a dU\dt-relay which will split the switchboard in two sections if the voltage is rising rapidly. This off course causes a 50% blackout, and is not desirable. Another option which my employer currently is using is based on the effect of the sensing loss, but i cant disclose it in detail here.
There is also the possibility to slow down the voltage rise by allowing healthy generators to absorb more reactive power before powering up the field current, but that is not a solution by itself (although it creates a few hundred milliseconds extra for us to act on).
I have scoured the web for information and best practices about this problem, but I really cant find anything. However, this forum pops up at the top of google search listings in very many other searches that i have, and i have the impression that the knowledge in this forum is quite high.
So do anyone here have any input about this special problem?
My principal (which is also my employer as I am both a student and a service engineer) is in the business of delivering diesel electric power systems for rigs and vessels with a high need for redundancy (DP class 2 and above).
The main challenge with detecting a loss of sensing voltage is that class requirements does not allow us to solely rely on the AVR itself to report about the failure. It also has a very dangerous impact on the power system as all of the ship's propulsion is powered by frequency converters which *will* trip if the voltage rises above a certain limit. This will render the vessel inoperable which can be very serious.
Some vendors has simply installed a dU\dt-relay which will split the switchboard in two sections if the voltage is rising rapidly. This off course causes a 50% blackout, and is not desirable. Another option which my employer currently is using is based on the effect of the sensing loss, but i cant disclose it in detail here.
There is also the possibility to slow down the voltage rise by allowing healthy generators to absorb more reactive power before powering up the field current, but that is not a solution by itself (although it creates a few hundred milliseconds extra for us to act on).
I have scoured the web for information and best practices about this problem, but I really cant find anything. However, this forum pops up at the top of google search listings in very many other searches that i have, and i have the impression that the knowledge in this forum is quite high.
So do anyone here have any input about this special problem?