What is generator reverse power protection?
What is reverse power? As we all know, the power direction of the generator should flow from the generator direction to the system direction. But for some reason, when the steam turbine loses its original power and the generator outlet switch fails to trip, the power direction changes from the system to the generator, that is, the generator becomes the motor running. At this time, the generator draws active power from the system, which is the reverse power.
Hazards of Reverse Power The generator reverse power protection is that when the steam turbine loses its original power due to the closure of the main valve for some reason, the generator turns into an electric motor to drive the steam turbine to rotate. The high-speed rotation of the steam turbine blades without steam will cause blast friction, especially in the last stage blades. Overheating may result, resulting in damage to the rotor blades. Therefore, the reverse power protection is actually the protection of the steam turbine operation without steam.
Program reverse power protection of generator The generator program reverse power protection is mainly to prevent the generator from suddenly tripping the outlet switch of the generator under the condition of a certain load and the main valve of the steam turbine cannot be fully closed. In this case, the turbo-generator set is prone to overspeed and even speeding. In order to avoid this situation, for some protections of non-short-circuit faults, after the action signal is issued, it first acts to close the main steam valve of the steam turbine. A short time limit constitutes the program reverse power protection, and the action acts on the full stop.
The difference between reverse power protection and program reverse power protection The reverse power protection is to prevent the generator from becoming a motor after reverse power, which drives the steam turbine to rotate, causing damage to the steam turbine. In the final analysis, I was afraid that the power of the prime mover would be insufficient, and I would be carried away by the system instead! The program reverse power protection is to prevent the main valve from not completely closing after the generator set is suddenly disengaged, resulting in overspeed of the steam turbine, so as to use reverse power to avoid it. In the final analysis, I was afraid that the power of the prime mover would be too strong and cause the unit to overspeed! Therefore, strictly speaking, reverse power protection is a kind of generator relay protection, but it mainly protects the steam turbine. The program reverse power protection is not a protection but an action process set to achieve program tripping, also called program tripping, which is generally used in shutdown mode. The most important thing is that the reverse power will trip as long as the set value is reached. In addition to reaching the set value, the program reverse power also requires the main valve of the turbine to be closed. Therefore, the reverse power action must be avoided when the unit is connected to the grid during the startup process.
