水力發(fā)電機(jī)組是實(shí)現(xiàn)水的位能轉(zhuǎn)化為電能的能量轉(zhuǎn)換裝置,一般由水輪機(jī)、發(fā)電機(jī)、調(diào)速器、勵(lì)磁系統(tǒng)、冷卻系統(tǒng)和電站控制設(shè)備等組成。
A hydroelectric generator set is an energy conversion device that converts the potential energy of water into electrical energy. It generally consists of a water turbine, generator, governor, excitation system, cooling system, and power station control equipment.
(1)水輪機(jī):常用的水輪機(jī)有沖擊式和反擊式兩種。
(1) Water turbine: There are two commonly used types of water turbines: impulse and reactive.
(2)發(fā)電機(jī):發(fā)電機(jī)大部分采用同步發(fā)電機(jī),其轉(zhuǎn)速較低,一般均在750r/min以下,有的只有幾十轉(zhuǎn)/分;由于轉(zhuǎn)速低,故磁極數(shù)較多;結(jié)構(gòu)尺寸和重量都較大;水力發(fā)電機(jī)組的安裝形式有立式和臥式兩種。
(2) Generators: Most generators use synchronous generators, with lower speeds, usually below 750r/min, and some only have a few tens of revolutions per minute; Due to low rotational speed, there are many magnetic poles; The structural size and weight are both large; There are two installation forms of hydroelectric power units: vertical and horizontal.
(3)調(diào)速和控制裝置(包括調(diào)速器和油壓裝置):調(diào)速器的作用是調(diào)節(jié)水輪機(jī)轉(zhuǎn)速,以保證輸出電能的頻率符合供電要求,并實(shí)現(xiàn)機(jī)組操作(開機(jī)、停機(jī)、變速、增、減負(fù)荷)及安全經(jīng)濟(jì)運(yùn)行。為此,調(diào)速器的性能應(yīng)滿足快速操作、反應(yīng)靈敏、迅速穩(wěn)定、運(yùn)行、維修方便等要求,它還需要可靠的手動(dòng)操作及事故停機(jī)裝置。
(3) Speed regulation and control device (including speed governor and oil pressure device): The function of the speed governor is to regulate the speed of the water turbine to ensure that the frequency of output electrical energy meets the power supply requirements, and to achieve unit operation (startup, shutdown, speed change, load increase, and decrease) and safe and economic operation. Therefore, the performance of the governor should meet the requirements of fast operation, sensitive response, rapid stability, convenient operation and maintenance, and it also requires reliable manual operation and emergency shutdown devices.
(4)勵(lì)磁系統(tǒng):水力發(fā)電機(jī)一般為電磁式同步發(fā)電機(jī),通過對(duì)直流勵(lì)磁系統(tǒng)的控制可實(shí)現(xiàn)電能的調(diào)壓、有功功率和無功功率的調(diào)節(jié)等控制,以提高輸出電能的質(zhì)量。
(4) Excitation system: Hydraulic generators are generally electromagnetic synchronous generators. By controlling the DC excitation system, voltage regulation of electrical energy, active and reactive power regulation, and other controls can be achieved to improve the quality of output electrical energy.
(5)冷卻系統(tǒng):小型水力發(fā)電機(jī)的冷卻主要采用空氣冷卻,以通風(fēng)系統(tǒng)向發(fā)電機(jī)定、轉(zhuǎn)子以及鐵心表面進(jìn)行冷卻。但隨著單機(jī)容量的增長,定、轉(zhuǎn)子的熱負(fù)荷不斷提高,為了在一定轉(zhuǎn)速下提高發(fā)電機(jī)單位體積的輸出功率,大容量水力發(fā)電機(jī)采用了定、轉(zhuǎn)子繞組直接水冷的方式;或者定子繞組用水冷,而轉(zhuǎn)子用強(qiáng)風(fēng)冷卻。
(5) Cooling system: Air cooling is mainly used for the cooling of small hydroelectric generators, and the ventilation system is used to cool the stator, rotor, and iron core surfaces of the generator. However, with the increase of single machine capacity, the thermal load of the stator and rotor continues to increase. In order to increase the output power of the generator per unit volume at a certain speed, large capacity hydraulic generators adopt direct water cooling of the stator and rotor windings; Alternatively, the stator winding can be cooled by water, while the rotor can be cooled by strong wind.
(6)電站控制設(shè)備:電站控制設(shè)備主要以微機(jī)為主,實(shí)現(xiàn)水力發(fā)電機(jī)的并網(wǎng)、調(diào)壓、調(diào)頻、功率因數(shù)的調(diào)節(jié)、保護(hù)和通信等功能。
(6) Power station control equipment: The power station control equipment mainly uses microcomputers to achieve functions such as grid connection, voltage regulation, frequency regulation, power factor regulation, protection, and communication of hydraulic generators.
(7)制動(dòng)裝置:額定容量超過一定值的水力發(fā)電機(jī)均設(shè)有制動(dòng)裝置,其作用是在發(fā)電機(jī)停機(jī)過程中,當(dāng)轉(zhuǎn)速降低到額定轉(zhuǎn)速的30%~40%時(shí),對(duì)轉(zhuǎn)子實(shí)施連續(xù)制動(dòng),以避免推力軸承因低轉(zhuǎn)速下油膜被破壞而燒損軸瓦。制動(dòng)裝置的另一作用是在安裝、檢修和起動(dòng)前,用高壓油頂起發(fā)電機(jī)的旋轉(zhuǎn)部件。制動(dòng)裝置采用壓縮空氣進(jìn)行制動(dòng)。
(7) Braking device: Hydraulic generators with a rated capacity exceeding a certain value are equipped with a braking device. Its function is to continuously brake the rotor when the speed drops to 30% to 40% of the rated speed during the shutdown process of the generator, in order to prevent the thrust bearing from burning the bearing pads due to the damage of the oil film at low speeds. Another function of the braking device is to use high-pressure oil to lift the rotating parts of the generator before installation, maintenance, and start-up. The braking device uses compressed air for braking.
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