Shenyang Getai Hydropower Equipment Co., Ltd.

Common Unit Failures Of Hydropower Generating Units

Nov. 25, 2019

Hydropower generators in hydropower stations often suffer from insufficient power and turbine failures, so how should they be solved? Hydraulic Turbine Generator Supplier will come to tell you.

The first kind of insufficient power of the turbine means that the power of the turbine cannot reach the guaranteed power under running water head. Main reasons for insufficient power of the unit:

The reasons for the insufficient or reduced power of the turbine are both hydraulic and mechanical; both design and manufacturing as well as installation and operation management.

1. The pollution inlet of the unit's water inlet is blocked and has a large area, which leads to an increase in hydraulic loss at the water inlet and a decrease in the area of the overflow, leading to a decrease in the overflow.

2. Due to weeds growing on the peripheral wall, shellfish microorganisms being adsorbed, or severe scabbing, the hydraulic loss will increase, and the flow area will decrease, resulting in a decrease in flow.

3. The flow channel of the small mixed flow turbine runner is narrow and twisted, and it is easy to be blocked by debris and debris, which affects the turbine power. When the fence is too large, debris can easily enter the runner with the flow of water; gravel and debris from the water diversion canal can also block the runner's flow path.

4. Due to sand wear, cavitation damage, or changes in airfoil shape after overhaul, the hydraulic loss of the turbine's over-flow parts will increase, and the turbine's over-flow will decrease, resulting in a decrease in the turbine's power.

5. The submerged depth at the outlet of the draft tube is not enough, which reduces the runner's overcurrent capability and causes the turbine's power to drop.

6. The installation height of the runner of the impulse turbine is not enough, so that there is not enough ventilation height between the runner and the downstream tailwater level, which causes the unit power to drop.

7. The main parts of the unit will naturally age, and the bearing capacity will decrease, which will cause the unit to fail to deliver its rated power. According to foreign data reports, the natural aging of the main parts of the turbine will reduce the efficiency of the turbine by 2% -3%.

Kaplan Turbine

Kaplan Turbine

Kaplan Turbine Design Factory will explain the solution in more detail.

1. Generator capacity increase

It is known from the comprehensive characteristic curve of hydraulic turbine operation that when the operating water head is higher than the designed water head, the power of the turbine is mainly limited by the capacity of the generator, and the guide vane opening does not reach the maximum opening at this time. Turbine cavitation performance, structural strength, and unit maintenance calculation meet the requirements. When the operating head is higher than the design head, the turbine power can be increased by opening large guide vanes to increase the unit power.

2. Transform the existing runner

By modifying the existing runner, the overcurrent capability of the turbine can be improved, thereby increasing the unit power. After the transformation, the cavitation and cavitation performance of the runner need to be verified by model tests.

3.Replace the runner

In the past ten years, through the use of computational fluid dynamics technology, the power of hydraulic turbines has been effectively increased. The new runner can use a different blade number and blade shape than the original power station runner.

The second type is the accident of lifting the turbine. Lifting accidents are more common in axial or diagonal flow turbines with low heads and long draft tubes. The height of the hoist is limited by the axial clearance between the runner and the top cover. When the hoisting accident is serious, it will cause the rotor blades to break, the top cover and thrust bearings to be damaged, and the fan to break, resulting in a vicious accident of generator burnout.

Methods and measures to prevent lift accidents:

1. When a lift accident occurs during the load shedding process (including the lift accident caused by the tailpipe backwater hammer); choose a reasonable water closing mechanism to close the law; a large number of access to the runner area through a good performance vacuum air valve air.

2. In the case of a lift accident when the phase change operation is performed under no-load conditions; replenish air to the runner area.

3. Consider from the structure of the unit; install anti-thrust bearings to prevent the rotating part of the unit from being lifted.

The above are some of the faults that may occur in the turbine, I hope to help everyone.

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