1. Operation mode before the accident:
The unit is running smoothly with normal load, the protection of the turbo-generator set is fully engaged, and no signal alarm and protection action are issued on the light word alarm panel.
Second, the phenomenon of sudden trip accident during steam turbine operation:
1. The speed of the turbine decreases (it may increase first and then decrease).
2. Steam turbine, generator related protection action light word is issued.
3. The main steam pressure rises and the bypass opens quickly.
4. Fire extinguishers in the furnace, de-excitation and demagnetization of generators, and switch to factory power.
Third, the process of sudden trip during steam turbine operation:
1. After the accident, quickly start the main engine AC lubricating oil pump to closely monitor the turbine speed drop.
2. Arrange a special person to record the protection action light word alarm and promptly notify each maintenance professional to confirm the cause of the accident and help recover as soon as possible.
3. Confirm the type of protection action and the correctness of the action as soon as possible, in order to recover as soon as possible, and analyze the following possibilities.
1). Steam turbine protection action:
① Man-made misoperation: If it is confirmed as such, immediately report the long value, restart the hydrogen-sealed reserve oil pump to flush the turbine's gate (should pay attention to avoid the critical speed), and quickly integrate the generator into the system.
②Protection misoperation: If the protection light word is issued and the steam turbine is turned off, but the steam turbine parameters are within the normal range and no abnormality is found after on-site inspection, notify the thermal engineer to check and verify the protection circuit If it cannot be repaired for a while, report to the chief of the value and relevant leaders, after formulating targeted measures, restore the unit to 3000 as soon as possible.
③ Correct action: The turbine body and various monitoring items should be strengthened for inspection and analysis. At the same time, the turbine and furnace should be notified for overhaul and inspection. After confirming that the protective action is correct, the unit should be shut down safely in accordance with the requirements of the regulations, waiting for overhaul or response. During the shutdown process, it is necessary to pay attention to the internal listening inspection of the steam turbine and draw and analyze the rotor idle curve, so as to be able to determine the actual problems of the unit in time and formulate targeted preventive measures.
2), generator protection action:
①Protection misoperation: If the protection light word alarm is issued and operates in full stop I, full stop II, or program trip, the steam turbine is tripped, but the parameters of the generator are in the normal range, no abnormal changes, and on the protection screen After the reset, when the light alarms have disappeared, it can be judged that the protection is malfunctioning. It should immediately report the long value and start the hydrogen seal oil backup pump in time, flush the steam turbine again, and notify the electrical inspection. After confirmation, it should be eliminated as soon as possible. Incorporate the unit into the system.
② Correct action: For example, at the same time of the light word alarm and protection action, there is a sudden change in the parameters of the generator side stator and rotor, which exceeds the protection prescribed range, or there is an obvious short circuit in the generator body and the primary and secondary connection parts. When it explodes, smokes or catches fire, it should be judged as correct action. At this time, it should be observed that the speed of the steam turbine has dropped, and the top shaft oil pump should be started in time to safely shut down the unit and put it into operation. The degree of failure and whether it can be restarted. If it can, then after the electrical personnel have made safety technical measures, the unit will be swept, fixed speed, connected to the grid as soon as possible, and recovered as soon as possible. Otherwise, safety isolation measures should be made according to the requirements of the electrical personnel. Start after processing is normal.