Hydroelectric generator set is an energy conversion device that converts potential energy of water into electric energy. It is generally composed of water turbine, generator, governor, excitation system, cooling system and power station control equipment.
(1) Hydraulic turbine: there are two types of hydraulic turbines commonly used: impulse type and reaction type.
(2) Generator: most generators are synchronous generators, with low speed, generally below 750r/min, and some only have dozens of revolutions/minute; Because of the low speed, there are many magnetic poles; Large structure size and weight; There are two types of installation of hydraulic generator units: vertical and horizontal.
(3) Speed regulation and control devices (including speed governor and oil pressure device): the role of the speed governor is to regulate the speed of the hydraulic turbine, so as to ensure that the frequency of the output electric energy meets the power supply requirements, and to achieve unit operation (startup, shutdown, speed change, load increase and load decrease) and safe and economic operation. Therefore, the performance of the governor shall meet the requirements of rapid operation, sensitive response, rapid stability, convenient operation and maintenance, and it also requires reliable manual operation and emergency shutdown devices.
(4) Excitation system: the hydraulic generator is generally an electromagnetic synchronous generator. Through the control of the DC excitation system, the voltage regulation of electric energy, the regulation of active power and reactive power and other controls can be achieved to improve the quality of output electric energy.
(5) Cooling system: air cooling is mainly used for the small hydraulic generator to cool the stator, rotor and iron core surface of the generator with ventilation system. However, with the increase of single unit capacity, the thermal loads of stator and rotor are constantly increasing. In order to increase the output power per unit volume of the generator at a certain speed, the large capacity hydraulic generator adopts the direct water cooling mode of stator and rotor windings; Or the stator winding is cooled by water, while the rotor is cooled by strong wind.
(6) Power station control equipment: the power station control equipment is mainly microcomputer based, which realizes the functions of grid connection, voltage regulation, frequency modulation, power factor regulation, protection and communication of hydraulic generators.
(7) Braking device: all hydraulic generators with rated capacity exceeding a certain value are equipped with braking device, which is used to continuously brake the rotor when the speed is reduced to 30%~40% of the rated speed during generator shutdown, so as to prevent the thrust bearing from burning due to oil film damage at low speed. Another function of the braking device is to jack up the rotating parts of the generator with high-pressure oil before installation, maintenance and starting. The braking device uses compressed air for braking
Post time: Oct-21-2022
