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Can you give me the normal setting for reverse power (as a % In and the time delay) of an alternator 60133 kVA Voltage 11000V Current 3156A Frequency 50 Hz 3 phases Speed 1500 rpm. The turbine is driven by steam.
rab,
Reverse power relay settings are normally determined based on an analysis of the power system at the site, including the type of prime mover (a steam turbine in your case), auxiliary loading, transformer capabilities, and system (grid) capabilities.
The alternator in use with your turbine-generator set is likely a synchronous machine, and synchronous machines can operate as either generators or motors, though most can't operate very well as motors. It's all a matter of current and torque flows and machine design and characteristics.
In the case of a steam turbine-driven generator, steam turbines generally do not like to be "driven" by the generator even for brief periods of time. It can be very, very disastrous to the steam turbine buckets. Spinning the steam turbine with the generator acting as a motor (when "reverse power" is flowing) can cause the steam turbine to try to "suck" steam in from the header putting reverse loads on the steam turbine buckets. Also, spinning the steam turbine buckets without sufficient steam flowing through the steam turbine can cause the buckets to overheat. So the reverse power relays of most steam turbine-driven generators are set to try to prevent any reverse power condition from every occurring, some even trip at very light positive power conditions to protect against "motorizing" the steam turbine.
Further, some utility operators do not want generators drawing "excessive" power from the grid during reverse power operations. Lastly, some transformers are not capable of extended operation with reverse current flows.
We can't make any recommendations about the specific equipment at your site because we don't have enough information about the equipment at your site. The best, but not the least expensive, thing to do is to commission a power system study of your site's configuration.
That could be most helpful in determining the reasons for the tripping during the lightning strike event at your site, and probably some recommendations for improving the system settings and coordination of relays would also result from the study.
But, we just don't have enough information to be able to give you and specific advice, other that what was offered above. You should really consult the steam turbine manufacturer and the architect/engineer of the plant where the equipment is located for more assistance, if you choose not to perform a complete power system study.
Many sites that have performed a power system study after being in operation for some time have drastically improved their availability and reliability by coordinating relay system settings, using new and improved relays (electronic relays), and working with the utility/system operator to pick settings which allow some more freedom of operation during system frequency disturbances, etc.
I have, though, seen a couple of sites that were very unhappy when, during the power system study, it was discovered that their relay settings were deemed too lax by the utility regulator and the changes caused more grid separation events than previously, which is what they were looking to reduce with the power system study. So, there are no guarantees with anything. Caveat emptor.
Reverse power relay settings are normally determined based on an analysis of the power system at the site, including the type of prime mover (a steam turbine in your case), auxiliary loading, transformer capabilities, and system (grid) capabilities.
The alternator in use with your turbine-generator set is likely a synchronous machine, and synchronous machines can operate as either generators or motors, though most can't operate very well as motors. It's all a matter of current and torque flows and machine design and characteristics.
In the case of a steam turbine-driven generator, steam turbines generally do not like to be "driven" by the generator even for brief periods of time. It can be very, very disastrous to the steam turbine buckets. Spinning the steam turbine with the generator acting as a motor (when "reverse power" is flowing) can cause the steam turbine to try to "suck" steam in from the header putting reverse loads on the steam turbine buckets. Also, spinning the steam turbine buckets without sufficient steam flowing through the steam turbine can cause the buckets to overheat. So the reverse power relays of most steam turbine-driven generators are set to try to prevent any reverse power condition from every occurring, some even trip at very light positive power conditions to protect against "motorizing" the steam turbine.
Further, some utility operators do not want generators drawing "excessive" power from the grid during reverse power operations. Lastly, some transformers are not capable of extended operation with reverse current flows.
We can't make any recommendations about the specific equipment at your site because we don't have enough information about the equipment at your site. The best, but not the least expensive, thing to do is to commission a power system study of your site's configuration.
That could be most helpful in determining the reasons for the tripping during the lightning strike event at your site, and probably some recommendations for improving the system settings and coordination of relays would also result from the study.
But, we just don't have enough information to be able to give you and specific advice, other that what was offered above. You should really consult the steam turbine manufacturer and the architect/engineer of the plant where the equipment is located for more assistance, if you choose not to perform a complete power system study.
Many sites that have performed a power system study after being in operation for some time have drastically improved their availability and reliability by coordinating relay system settings, using new and improved relays (electronic relays), and working with the utility/system operator to pick settings which allow some more freedom of operation during system frequency disturbances, etc.
I have, though, seen a couple of sites that were very unhappy when, during the power system study, it was discovered that their relay settings were deemed too lax by the utility regulator and the changes caused more grid separation events than previously, which is what they were looking to reduce with the power system study. So, there are no guarantees with anything. Caveat emptor.
