Flush the water turbine with potential energy or kinetic energy, and the water turbine starts to rotate. If we connect the generator to the water turbine, the generator can start to generate electricity. If we raise the water level to flush the turbine, the turbine speed will increase. Therefore, the larger the water level difference is, the greater the kinetic energy obtained by the turbine is, and the higher the convertible electric energy is. This is the basic principle of hydropower.
The energy conversion process is: the gravitational potential energy of the upstream water is converted into the kinetic energy of the water flow. When the water flows through the turbine, the kinetic energy is transferred to the turbine, and the turbine drives the generator to turn the kinetic energy into electric energy. Therefore, it is the process of converting mechanical energy into electrical energy.
Due to different natural conditions of hydropower stations, the capacity and speed of hydro generator units vary widely. Generally, small hydro generators and high speed hydro generators driven by impulse turbines mostly adopt horizontal structures, while large and medium speed generators mostly adopt vertical structures. Since most hydropower stations are far away from cities, they usually need to supply power to loads through long transmission lines, therefore, the power system puts forward higher requirements for the operation stability of hydro generators: motor parameters need to be carefully selected; The requirements for the moment of inertia of the rotor are large. Therefore, the appearance of hydro generator is different from that of steam turbine generator. Its rotor diameter is large and its length is short. The time required for starting and grid connection of hydro generator units is relatively short, and the operation dispatching is flexible. In addition to general power generation, it is particularly suitable for peak shaving units and emergency standby units. The maximum capacity of water turbine generator units has reached 700000 kilowatts.
As for the principle of generator, high school physics is very clear, and its working principle is based on the law of electromagnetic induction and the law of electromagnetic force. Therefore, the general principle of its construction is to use appropriate magnetic conductivity and conductive materials to form a magnetic circuit and circuit for mutual electromagnetic induction to generate electromagnetic power and achieve the purpose of energy conversion.
The water turbine generator is driven by the water turbine. Its rotor is short and thick, the time required for unit startup and grid connection is short, and the operation dispatching is flexible. In addition to general power generation, it is particularly suitable for peak shaving unit and emergency standby unit. The maximum capacity of water turbine generator units has reached 800000 kilowatts.
The diesel generator is driven by an internal combustion engine. It is quick to start and easy to operate, but its power generation cost is high. It is mainly used as emergency backup power, or in areas where the large power grid does not reach and mobile power stations. The capacity ranges from several kilowatts to several kilowatts. The torque output on the diesel engine shaft is subject to periodic pulsation, so resonance and shaft breakage accidents must be prevented.
The speed of the hydro generator will determine the frequency of the alternating current generated. To ensure the stability of this frequency, the speed of the rotor must be stabilized. In order to stabilize the speed, the speed of the prime mover (water turbine) can be controlled in a closed loop control mode. The frequency signal of the AC power to be sent out is sampled and fed back to the control system that controls the opening and closing angle of the guide vane of the water turbine to control the output power of the water turbine. Through the feedback control principle, the speed of the generator can be stabilized.
Post time: Oct-08-2022
