A hydraulic turbine is an electrical machine that converts the energy of water flow into rotating mechanical energy. It is a turbine machine among fluid machines. As early as around 100 BC, the prototype of a hydraulic turbine – a waterwheel – appeared in China, used to lift irrigation and drive grain processing equipment. Modern hydraulic turbines are mainly installed in hydroelectric power stations and are used to drive generators to produce electricity. In a hydroelectric power station, water from the upstream reservoir is directed to the turbine via the bypass pipe, pushing the turbine wheel to rotate and driving the generator to produce electricity. The water that has finished its work is discharged downstream through the tailrace. The higher the water height and flow rate, the higher the power output of the turbine. The main operating parametersement of the turbine:
1. Height H (meter)
The difference in unit energy between two sections of continuous water flow is called the height. The water height is an important parameter of a hydraulic turbine. Its size directly affects the efficiency of the turbine and the choice of turbine type.
2. Flow Rate
The amount (volume) of water flowing through the turbine per unit time is called the turbine flow rate, represented by Q. Usually expressed in cubic meters per second.
3. Output
The energy of the water flow flowing through the turbine per unit time is called the “output of the water flow” through the turbine, represented by Np^0. Np^0=9.81QH (kilowatt).
4. Efficiency
The ratio of the turbine output N to the output Np^0 of the water flow through the turbine is called the turbine efficiency, represented by eta. . Obviously, efficiency is the efficient use of the energy of the water flow by the turbine.th surface. It is a dimensionless physical quantity expressed as a percentage (%).
5. Rotational speed
The number of rotations of the main shaft of the hydraulic turbine in unit of time is called the rotational speed of the hydraulic turbine, represented by n, and the unit is generally "revolution/ min".
1. The function of water turbine: convert the kinetic energy of water flow into rotating mechanical energy.
2. Lifting refers to a serious accident in which when the turbine guide vane is suddenly closed, a vacuum is instantly formed in the suction tube, causing negative water hammer, causing waste water to flow back and a breakup. the upper cover of the turbine. In order to prevent the phenomenon of lifting from occurring, a vacuum breaking valve is installed on the upper cover of the turbine to break the vacuum.
3. The biggest advantage of axi flow vane runneral is that efficiency can always remain optimal. The guide vanes and blades are in a co-connected relationship. When the opening of the guide vanes changes, the opening of the blades also changes accordingly, so that efficiency is always optimal.
4 Thrust bearing: supports the weight of the entire rotating part of the generator and the axial thrust of the water. According to the different installation positions of the stops, the vertical units are divided into two categories: suspension units with stops installed on the upper part of the rotor, and umbrella units with stops installed on the lower part of the rotor.
5. Functions of transformer oil: insulation and cooling. Bearing oil (also called turbine oil) has the functions of: lubrication and cooling.
Primary equipment
1. The main primary equipment is: a generator (converts the mechanical energy of rotationon of the turbine into electrical energy), a power transformer (increases the output voltage of the generator to the corresponding voltage level then connected to the electrical network), Circuit breaker (connects or disconnects the primary circuit), isolation switch ( makes the primary circuit an obvious disconnection point, creating conditions for equipment maintenance), voltage transformer (measures the voltage of the primary circuit and transmits the measured voltage to protection, synchronization, excitation, measuring meters, etc. . requiring voltage), current transformer (measures the current of the primary circuit and transmits the measured current to protection, excitation, measurement meters, etc. requiring current).
2. The generator magnetic pole is a device that generates a magnetic field and is installed at the end of the generator rotor. It is in fact an electromagnet. When current flows through the coil, the niron core generates magnetic lines of force. As the rotor rotates, the magnetic lines of force also rotate. If the stator wire is relatively cut, an induced voltage is generated. on the stator. This is the principle of electromagnetic induction. The relationship between the number of magnetic pole pairs and the rotation speed: (frequency * 60 seconds) / the number of magnetic pole pairs = rotation speed For example: 50HZ * 60 seconds / 24 magnetic pole pairs = 125 revolutions per minute<. /p>
3. The main application of electromagnetic induction in power plants. The equipment is: synchronous generator, asynchronous motor.
4. The voltage transformer is connected to the primary circuit and it is strictly forbidden to short circuit the secondary side; the current transformer is connected in series in the primary circuit and the secondary side is strictly prohibited. forbidden to be in copen circuit.
5. Transformer protection mainly includes: main transformer differential protection, gas protection, main transformer zero sequence, main transformer pressure release, etc. Gas protection function: When the internal insulation force of the transformer decreases slightly, a small arc will be generated, but it will not operate the differential protection. In order to detect or eliminate this fault as quickly as possible, gas protection plays a role. The arc will break down the transformer oil into small bubbles (i.e. gas) or increase the flow rate of the oil (when internal discharge is large). The bubbles will cause the light gas to act and send a signal; when the oil flow is too high, the heavy gas will act on and off.
6. When loading the main transformer to full voltage, all proteTransformer actions must be installed correctly. At the same time, consider using the system (line) to load the transformer as much as possible and avoid using it. a generator to charge it. (The reason is that a large excitation inrush current will be generated during charging, which will damage the generator.)
7. The role of zinc oxide surge arrester: preventing the occurrence of operating overvoltages and atmospheric overvoltages.
8. The function of a circuit breaker: to connect or close a circuit. The main arc extinguishing means used are: sulfur hexafluoride, vacuum, insulating oil, etc.
9. In case of power failure: Shut down the load side first, then the power side. When sending power: send the power side first, then the load side.
10. The generator generates three-phase alternating current. Why, apart from the problems of power supply and foodation, you can refer to relevant professional books, such as electrical engineering. I can't explain it simply, my level is limited, I'm sorry.
11. Ohm's Law: Resistance R = Voltage U / Current I