Hydroelectric power generation and thermal power generation both have exciters. The exciters are usually connected to the same large shaft as the generator. When the large shaft rotates under the drive of the main engine, it drives the rotation of the generator and the exciter. at the same time. The exciter is a DC generator that outputs DC energy, which is sent to the rotor coil through the slip ring of the generator rotor to cause the rotor to generate a magnetic field, thereby generating an induced electromotive force in the generator stator. . Currently, the exciters of larger generator sets are being replaced by self-excited AC excitation systems. Most of them use the voltage at the generator output to be transformed by excitation, and then converted into direct current through the rectifier device. then sent to the generator through the ringed rotore collector of the generator rotor. When using this type of system, initial excitation of the generator must be performed each time the machine is powered up, which involves adding initial excitation to the generator and establishing the initial generator voltage.
The excitation of the old-fashioned exciter relies on its own residual magnetism. This residual magnetism can cause the exciter to generate electricity, but the energy is very low and the voltage is very low. the current passes through the excitation of the exciter. After the coil, the effect of residual magnetism is strengthened. This strengthened magnetic field continues to cause the exciter to generate electricity, which has a higher energy than the residual magnetism. Then, by repeating this process over and over again, the voltage put out by the exciter becomes higher and higher. emitted by the exciter first generates electricity for itself. It is used to buildre its own capacity and only provides generator excitation when a certain high voltage is reached. The excitation system of modern large generator sets uses a microcomputer excitation system, and its initial excitation is provided by the initial excitation power supply, which is provided by the power grid or DC battery of the power station electric.
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1. The function of the hydraulic turbine: convert the kinetic energy of the water flow into rotational 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 break. the upper cover of the turbine. In order to prevent the phenomenon of lifting from occurringe, a vacuum breaking valve is installed on the upper cover of the turbine to break the vacuum.
3. The biggest advantage of the axial flow vane runner is that the 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: lubrication and cooling.
Primary equipment
1. The main primary equipment is: a generator (converts the mechanical energy of rotation of the turbine into electrical energy), a power transformer (increases the output voltage of the generator to the corresponding voltage level and then connected to the electrical network) , circuit breaker (to connect or disconnect the primary circuit), disconnector (to form an obvious disconnection point in the primary circuit, creating conditions for equipment maintenance), voltage transformer (to measure the voltage of the primary circuit) voltage, transmit the measured voltage to protection, synchronization, excitation, measuring meters, etc. which require voltage), current transformer (measure the primary circuit current, transmit the measured current to the protection which requires current, excitation, measurement meters, etc.).
2. Lhe 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 passes through the coil, the iron 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 circuitand 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. prohibited from being in open 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 make the g actaz light and will 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 transformer protections must be in place 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. Lors of sending power: send the power side first, then the load side.
10. The generator generates three-phase alternating current. Why, in addition to power supply and power supply issues, 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
Domestic Turbine Generator Manufacturers in China
1. hereinafter referred to as Harbin Electric)
2. Dongfang Electric Group Dongfang Electric Co., Ltd. (hereinafter referred to as Dongfang Electric)
3. , Ltd. (hereinafter referred to as Guangdong Hongyuan)
4.) (hereinafter referred to as Yangtze Power)
5. Sichuan Dongfeng Motor Co., Ltd. (hereinafter referred to as Dongfeng Motor)
6. Lanzhou Lanzhou Landian Motor Co., Ltd. (hereinafter referred to as Landian Motor)
7 Fujian Nandian Co., Ltd. (hereinafter referred to as Fujian Nandian)
8. (here(nearly called Kunming Electric)
9. Nanning General Power Generation Equipment Factory
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