The speed of water turbines is relatively low, especially the vertical water turbine. In order to generate 50Hz AC, the water turbine generator adopts multi pair magnetic pole structure. For the water turbine generator with 120 revolutions per minute, 25 pairs of magnetic poles are required. Because it is difficult to see the structure of too many magnetic poles, this courseware introduces a hydraulic turbine generator model with 12 pairs of magnetic poles.
The rotor of hydro generator adopts salient pole structure. Figure 1 shows the magnetic yoke and magnetic pole of the generator. The magnetic pole is installed on the magnetic yoke, which is the path of the magnetic field line of the magnetic pole. The generator model has 24 magnetic poles between North and south, and each magnetic pole is wound with an excitation coil. The excitation power is provided by the excitation generator installed at the end of the main shaft or by the external thyristor excitation system (the collector ring supplies power to the excitation coil).
The magnetic yoke is installed on the rotor support, the generator main shaft is installed in the center of the rotor support, and the excitation generator or collector ring is installed at the upper end of the main shaft.
The generator stator core is made of silicon steel sheets with good magnetic conductivity, and many slots are evenly distributed in the inner circle of the core to embed the stator coil.
The stator coil is embedded in the stator slot to form a three-phase winding. Each phase winding is composed of multiple coils and arranged according to a certain law.
The hydro generator is installed on the concrete pouring turbine pier, and the turbine pier is installed with the turbine base. The turbine base is the installation base of the stator core and the shell of the hydro generator. The heat dissipation device is installed on the shell of the turbine base to reduce the temperature of the cooling air of the generator; The lower frame is also installed on the pier. The lower frame is equipped with thrust bearing, which is used to install the generator rotor. The thrust bearing can bear the weight, vibration, impact and other forces of the rotor.
The stator core and stator coil are installed on the base. The rotor is inserted in the middle of the stator and has a small gap with the stator. The rotor is supported by the thrust bearing of the lower frame and can rotate freely. The upper frame is installed, and the guide bearing is installed in the center of the upper frame to prevent the main shaft of the generator from shaking and keep it in the central position stably. After laying the upper platform floor and installing the brush device or excitation motor, a hydro generator model is installed.
The three-phase AC electromotive force of 12 cycles will be induced by the rotation of the model rotor of the hydro generator. When the rotor speed is 250 revolutions per minute, the frequency of the generated AC is 50 Hz.
Post time: Apr-14-2022
