水力發電機組是實現水的位能轉化為電能的能量轉換裝置,一般由水輪機、發電機、調速器、勵磁系統、冷卻系統和電站控制設備等組成。
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:常用的水輪機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)發電機:發電機大部分采用同步發電機,其轉速較低,一般均在750r/min以下,有的只有幾十轉/分;由于轉速低,故磁極數較多;結構尺寸和重量都較大;水力發電機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)調速和控制裝置(包括調速器和油壓裝置):調速器的作用是調節水輪機轉速,以保證輸出電能的頻率符合供電要求,并實現機組操作(開機、停機、變速、增、減負荷)及安全經濟運行。為此,調速器的性能應滿足快速操作、反應靈敏、迅速穩定、運行、維修方便等要求,它還需要可靠的手動操作及事故停機裝置。
(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)勵磁系統:水力發電機一般為電磁式同步發電機,通過對直流勵磁系統的控制可實現電能的調壓、有功功率和無功功率的調節等控制,以提高輸出電能的質量。
(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:小型水力發電機的冷卻主要采用空氣冷卻,以通風系統向發電機定、轉子以及鐵心表面進行冷卻。但隨著單機容量的增長,定、轉子的熱負荷不斷提高,為了在一定轉速下提高發電機單位體積的輸出功率,大容量水力發電機采用了定、轉子繞組直接水冷的方式;或者定子繞組用水冷,而轉子用強風冷卻。
(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)電站控制設備:電站控制設備主要以微機為主,實現水力發電機的并網、調壓、調頻、功率因數的調節、保護和通信等功能。
(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)制動裝置:額定容量超過一定值的水力發電機均設有制動裝置,其作用是在發電機停機過程中,當轉速降低到額定轉速的30%~40%時,對轉子實施連續制動,以避免推力軸承因低轉速下油膜被破壞而燒損軸瓦。制動裝置的另一作用是在安裝、檢修和起動前,用高壓油頂起發電機的旋轉部件。制動裝置采用壓縮空氣進行制動。
(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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