Summary The water turbine is indispensable for the conversion of water into electrical energy.Because of its high quickness, high flexibility, high efficiency, and strong stability,In the operation of power s
Among the energy currently used to generate electricity, water is the most economical and environmentally friendly energy source, and fire.Compared with nuclear power generation and nuclear power generation, hydropower not only reduces costs but also increases safety, and stability. The water turbine is indispensable for the conversion of water into electrical energy.Because of its high quickness, high flexibility, high efficiency, and strong stability,In the operation of power systems, hydropower has also gradually occupied an important position. As the hydraulic prime mover for converting electrical energy, the water turbine is the core equipment of the hydropower station.
The process of converting water into electricity is: water can first pass through the water turbine, turning its own energy
Turned into mechanical energy, the mechanical energy is then converted into electrical energy by the electric motor, and the electric energy is transmitted through the electric grid.
Delivered to thousands of households. An important factor related to the technology and funding of hydropower stations is the quality of power.
Quantity, and the performance of the water turbine will directly affect the quality of the output power. Therefore, the first thing ,It is necessary to understand the operation of the water turbine.
Water Turbine operation process
The transition process of a water turbine to convert water energy into mechanical energy can be divided into the following four
process.
1 Unit start-up process
The startup process of the unit refers to the shutdown state after the water turbine is stopped.
Start turning and then synchronize to the process of incorporating into the grid. Research focus is on improving the thrust shaft
Working conditions, shorten the start-up time of the machine and better integrate the generator into the grid.
Taking a propeller water turbine as an example, after the unit sends a start pulse, the opening of the vane is gradually expanded.
Large, axial water thrust and torque of the runner also increase, when the torque is greater than the friction torque
The water turbine then turns on.
2 Unit increase and decrease load process
The change of load during the operation of the unit can be divided into two types: one is the load from the air
The load is increased to the specified value or reduced from the state of the load to the no-load; the other is the load
Increase or decrease between minimum power and rated power. Also used as a propeller water turbine
For example, the process of reducing the load to no load to the stop is analyzed, and the stop signal is sent.
After that, the vanes and runner blades stop expanding and rotating. The blade stops longer than the vane
The stop time, the unit is separated from the grid, the vane is closed, and the output is output.
The rate is almost zero, the turbine speed is slowed down, the unit enters the braking state, and the water turbine torque changes.
In a negative value. After that, when the speed drops to half, the action starts to stop the water turbine until it turns.
The speed drops to a certain value and the blade angle increases to the starting angle.
3 Unit load rejection process
The unit charge process is the sudden removal of all loads during the operation of the motor unit.
The main characteristic parameters in this process include the speed of the unit, the pressure diversion pipe and the pressure in the snail shell.
Also in the enthalpy charge of the rotary turbine, the speed of the water turbine after leaving the grid,steep increase, the vane runs off.
The torque is initially increased, as the blade angle is reducedSmall, torque and flow are also decreasing.
However, the head of the water will increase due to the action of the water hammer.After the torque is gradually reduced to zero, the speed also reaches the peak. The water turbine enters the brake.
After the state, the torque is reduced to a negative value, the speed begins to decrease, the guide vane reopens, and the unit is unloaded run.
4 Unit speed runaway process
When the main system of the regulating device fails, the centrifugal force and the unbalanced mass of the rotating body cause the unit speed to increase sharply. When the friction loss due to the rising speed is balanced with the input water flow energy, the speed reaches a certain stability. The maximum value of this process is called the speed flyaway process.
Working conditions are serious operational accidents. In order to prevent the unit from continuing to operate in this state, it must be equipped with anti-flying protection devices.
When the axial flow turbine flies, it will be controlled by the accidental pressure regulating valve. The specific process is as follows:
After the unit leaves the grid and enters the runaway state,
The axial water thrust and torque of the turbine are reduced,
The accidental pressure valve guide leaf signals that it begins to close.
The speed continues to increase until the torque reaches zero and the axial water thrust becomes negative, reaching a maximum and then starting to fall.
When the unit enters the braking state, it stops, and the rotor blades are turned to the position where the opening angle is activated.
