Hydro generator is a machine that converts the potential energy and kinetic energy of water flow into mechanical energy, and then drives the generator into electrical energy. Before the new unit or overhauled unit is put into operation, the equipment must be comprehensively inspected before it can be officially put into operation, otherwise there will be endless trouble.
1、 Inspection before unit startup
(1) Remove sundries in penstock and volute;
(2) Remove the dirt from the air duct;
(3) Check whether the shear pin of the water guide mechanism is loose or damaged;
(4) Check whether there are sundries inside the generator and air gap;
(5) Check whether the brake air brake operates normally;
(6) Check the main shaft sealing device of hydraulic turbine;
(7) Check the collector ring, exciter carbon brush spring pressure and carbon brush;
(8) Check whether all parts of oil, water and gas systems are normal. Whether the oil level and color of each bearing are normal
(9) Check whether the position of each part of the governor is correct and whether the opening limit mechanism is at the zero position;
(10) Conduct the action test of butterfly valve and check the working condition of travel switch;
2、 Precautions during unit operation
(1) After the machine is started, the speed shall rise gradually, and shall not rise or fall suddenly;
(2) During operation, pay attention to the lubrication of each part, and it is specified that the oil filling place shall be filled every five days;
(3) Check the bearing temperature rise every hour, check the sound and vibration, and record in detail;
(4) During shutdown, turn the hand wheel evenly and slowly, do not close the guide vane too tightly to prevent damage or jamming, and then close the valve;
(5) For shutdown in winter and long-term shutdown, the accumulated water shall be drained to prevent freezing and corrosion;
(6) After long-term shutdown, clean and maintain the whole machine, especially lubrication.
3、 Shutdown treatment during unit operation
During the operation of the unit, the unit shall be shut down immediately in case of any of the following conditions:
(1) The unit operation sound is abnormal and invalid after treatment;
(2) Bearing temperature exceeds 70 ℃;
(3) Smoke or burnt smell from generator or exciter;
(4) Abnormal vibration of the unit;
(5) Accidents in electrical parts or lines;
(6) Loss of auxiliary power and invalid after treatment.
4、 Maintenance of hydraulic turbine
(1) Normal maintenance — it is required to start, operate and shut down. The capping oil cup shall be filled with oil once a month. The cooling water pipe and oil pipe shall be checked frequently to keep smooth and normal oil level. The plant shall be kept clean, the post responsibility system shall be established, and the shift handover work shall be done well.
(2) Daily maintenance – carry out daily inspection according to the operation, check whether the water system is blocked or stuck by wood blocks, weeds and stones, check whether the speed system is loose or damaged, check whether the water and oil circuits are unblocked, and make records.
(3) Unit overhaul — determine the overhaul time according to the number of unit operation hours, generally once every 3 ~ 5 years. During the overhaul, the severely worn and deformed parts shall be replaced or repaired to the original factory standard, such as bearings, guide vanes, etc. after the overhaul, the same commissioning as the newly installed unit shall be carried out.
5、 Common faults of hydraulic turbine and their solutions
(1) Kilowatt meter fault
Phenomenon 1: the indicator of the kilowatt meter drops, the unit vibrates, the ferry increases, and other meter needles swing.
Treatment 1: keep the submergence depth of draft tube more than 30cm under any operation or shutdown.
Phenomenon 2: the kilowatt meter drops, other meters swing, the unit vibrates and swings with collision sound.
Treatment 2: stop the machine, open the access hole for inspection and restore the locating pin.
Phenomenon 3: the kilowatt meter drops, the unit can not reach full load when fully opened, and other meters are normal.
Treatment 3: stop the machine to remove the sediment downstream.
Phenomenon 4: the kilowatt meter drops and the unit is fully opened without full load.
Treatment 4: stop the machine to adjust the belt or wipe the belt wax.
(2) Unit vibration, bearing temperature fault
Phenomenon 1: the unit vibrates and the pointer of the kilowatt meter swings.
Treatment 1: stop the machine to check the draft tube and weld the cracks.
Phenomenon 2: the unit vibrates and sends out Bearing Overheating signal.
Treatment 2: check the cooling system and restore the cooling water.
Phenomenon 3: the unit vibrates and the bearing temperature is too high.
Treatment 3: replenish air to the runner chamber;.
Phenomenon 4: the unit vibrates and the temperature of each bearing is abnormal.
Treatment 4: raise the tail water level, even emergency shutdown, and tighten the bolts.
(3) Governor oil pressure fault
Phenomenon: the light plate is on, the electric bell rings, and the oil pressure of the oil pressure device drops to the fault oil pressure.
Treatment: operate the opening limit handwheel to make the red needle coincide with the black needle, cut off the power supply of the flying pendulum, turn the governor switching valve to the manual position, change the manual oil pressure operation, and pay close attention to the operation of the unit. Check the automatic oiling circuit. If it fails, start the oil pump manually. Handle it when the oil pressure rises to the upper limit of working oil pressure. Or check the oil pressure device for air leakage. If the above treatment is invalid and the oil pressure continues to drop, stop the machine with the consent of the shift supervisor.
(4) Automatic governor failure
Phenomenon: the governor cannot operate automatically, the servomotor swings abnormally, which makes the frequency and load unstable, or some part of the governor produces abnormal sound.
Treatment: immediately change to oil pressure manual, and the personnel on duty shall not leave the governor control place without authorization. Check all parts of the governor. If the fault cannot be eliminated after treatment, report to the shift supervisor and request shutdown for treatment.
(5) Generator on fire
Phenomenon: the generator wind tunnel emits thick smoke and has the smell of burnt insulation.
Treatment: manually lift the emergency stop solenoid valve, close the guide vane, and press the opening limit red needle to zero. After the excitation switch jumps off, quickly turn on the fire faucet to extinguish the fire. In order to prevent asymmetric heating deformation of generator shaft, slightly open the guide vane to keep the unit rotating at low speed (10 ~ 20% rated speed).
Precautions: do not use water to extinguish the fire when the unit is not tripped and the generator has voltage; Do not enter the generator to extinguish the fire; It is strictly prohibited to use sand and foam extinguishers to put out fires.
(6) The unit runs too fast (up to 140% of rated speed)
Phenomenon: the light plate is on and the horn sounds; The load is thrown off, the speed increases, the unit makes overspeed sound, and the excitation system makes forced reduction movement.
Treatment: in case of overspeed caused by load rejection of the unit and the governor cannot be quickly closed to the no-load position, the opening limit handwheel shall be operated manually to the no-load position. After comprehensive inspection and treatment, when it is determined that there is no problem, the shift supervisor shall order the load. In case of overspeed caused by governor failure, the shutdown button shall be pressed quickly. If it is still invalid, the butterfly valve shall be closed quickly and then shut down. If the cause is not found out and the treatment is not carried out after the unit is over speed, it is prohibited to start the unit. It shall be reported to the plant leader for research, find out the cause and treatment before starting the unit.
Post time: Sep-29-2021
