Shenyang Getai Hydropower Equipment Co., Ltd.

Problems in The Operation of Water Turbine Generators and Countermeasures

Oct. 12, 2020



1. The main pressure valve of the Hydro-Generator is stuck, and the main servomotor is suddenly opened to the maximum or closed to zero


the reason:


The piston and the valve body are poorly assembled, and there is water in the oil that causes the piston to be rusted or debris stuck to the piston. 


Approach:


When the main pressure valve is stuck, the main valve should be shut down immediately.


After stopping, when the main servomotor is automatically closed, the operating handwheel does not work.


It means that the upper part of the piston is stuck. At this time, knock down the upper disc of the auxiliary servomotor to return it to the middle position.


When the stroke of the main servomotor has been opened, the handwheel operation to reduce the load is invalid, indicating that the lower part of the piston is stuck.


At this time, the outer part connected with the auxiliary servomotor piston can be pried up and reciprocate several times to return it to the middle position.


Problems in The Operation of Water Turbine Generators and Countermeasures

Hydro-Generator

2. The oil pressure of the oil pressure device drops


Reasons for the drop in oil pressure of the oil press:


The oil source of the oil pump motor is interrupted or the fuse is blown, the motor is burned out, the screw, the oil pump, the screw are damaged, the oil pipeline is broken, the contact of the pressure relay is poor or the contact of the electric contact pressure gauge is poor.


phenomenon:


A low oil pressure alarm is issued, and the pressure gauge of the oil pressure device is found to be low.


Approach:


If the unit is in operation, the air supplement should be restored as soon as possible.


When the two pumps can be started again, or the pump does not start after starting, the main cutting should be shut down.


If the motors of the two oil pumps are running and the oil pressure still cannot rise, check the oil level of the oil pressure tank.


If the oil level is high, check the inflation valve of the oil pressure tank. If the valve door is not tight, try to close it tightly and adjust the oil level to restore the oil pressure.


If it is not a gas leak, the main valve should be shut down for unknown reasons.


If the electrical contact pressure gauge contacts do not work well, turn the power control switch of the oil pump motor to the "manual" position, and then stop and check after the oil pressure is restored.


3. Generator overload


the reason:


An accident occurred on a high-voltage line of the power grid, the line voltage dropped significantly, and when the unit was running on an independent small network, the power supply load was too large, and the unit was connected to the user line.


Due to the sudden power failure of this line, the user's load is close to the unit's power supply load, so overload operation will occur.


The hydro-generator is not allowed to be overloaded during normal operation. In the event of an accident, the generator can bear short-term overload.


Because the generator has a certain limit to the temperature rise and the temperature resistance of insulating materials.


Therefore, short-term overload has little effect on the life of insulating materials, and there is a certain process of insulation aging.


The insulation material becomes brittle, the dielectric loss increases, and the breakdown voltage strength decreases. It requires a high temperature action time.


The shorter the high temperature action time, the shorter the damage degree of the insulating material.


Accidents or special circumstances require generator overload operation.


When the generator stator current exceeds the allowable value, the power voltage of the generator should be checked first.


And observe the time elapsed when the stator current exceeds the allowable value.


Then use the method of reducing the excitation current to reduce the stator current to the rated current value, but must not make the power factor too high and the stator voltage too low.


If the method does not work at this time, you must reduce the active load of the generator or cut off a load to reduce the stator current to the allowable value.


In addition to the failure causes discussed above, there are many factors in the generation of turbine vibration.


In the actual fault diagnosis and elimination, maintenance personnel are required to make corresponding eliminations based on past experience and the working conditions of each component of the unit and the replacement time of the components.


In this way, potential safety hazards of the unit caused by vibration failure are avoided, and the safe and stable operation of the Turbine is guaranteed.


By learning from the above experience, the damage to the unit can be minimized.


As a Hydro Water Power Plant, whether it is in the main flood season, flood discharge power generation or normal irrigation power generation, it should ensure that the unit is in the best and best operating state.


Generate the most electricity with the least amount of water, and create the greatest benefits for society as a unit.


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