The stator core of the generator is divided into 13 air zones along the axial direction. 6 air inlet zones and 7 air outlet zones are arranged alternately. The air inlet zone and the air outlet zone are connected to each other respectively. There are Several radial vents. The cooling of the rotor winding adopts the "air gap air taking" system: two rows of diagonal flow holes in different directions are drilled into the rotor bar to the bottom of the slot, thus forming several parallel diagonal flow channels along the axial direction of the rotor body. Through these channels, the cooling hydrogen gas alternately enters and flows out of the air duct of the rotor winding air inlet, forcing the cooling hydrogen gas to reach the bottom of the conductor slot through the oblique flow channel at a speed that matches the rotor speed, and then turns to the other side along the same oblique flow path. The flow channel flows out of the conductor. The cold air blown from each air inlet is divided into two oblique flow channels and flows into the conductor in two directions. Similarly, there are two air outlet channels that merge together and flow out from the air outlet into the air gap. Therefore, each channel has a "V" shape when viewed from the longitudinal section of the parallel bar, and a "U" shape from the cross-sectional view of the vertical bar. The inlet and outlet areas of the rotor winding cooling air correspond to the inlet and outlet areas of the stator core.
A generator is a mechanical device that converts other forms of energy into electrical energy. It is driven by a water turbine, steam turbine, diesel engine or other power machinery to convert the energy generated by water flow, air flow, fuel combustion or atomic nuclear fission into Mechanical energy is transmitted to the generator, which is then converted into electrical energy. Generators are widely used in industrial and agricultural production, national defense, science and technology and daily life.
Generators come in many forms, but their working principles are all based on the law of electromagnetic induction and the law of electromagnetic force. Therefore, the general principle of its construction is: use appropriate magnetic and conductive materials to form magnetic circuits and circuits that conduct electromagnetic induction with each other to generate electromagnetic power and achieve the purpose of energy conversion.
Operating characteristics:
The main features that characterize the performance of synchronous generators are no-load characteristics and load operating characteristics.
These characteristics are an important basis for users to choose generators.
No-load characteristics:
When the generator is not connected to a load, the armature current is zero, which is called no-load operation. At this time, the three-phase winding of the motor stator only has the no-load electromotive force E0 (three-phase symmetry) induced by the excitation current If, and its size increases with the increase of If. However, due to the saturation phenomenon in the motor magnetic circuit core, the two are not proportional. The curve reflecting the relationship between the no-load electromotive force E0 and the excitation current If is called the no-load characteristic of the synchronous generator.
Armature reaction:
When the generator is connected to a symmetrical load, the three-phase current in the armature winding will produce another rotating magnetic field, which is called the armature reaction magnetic field. Its speed is exactly equal to the speed of the rotor, and the two rotate synchronously.
Both the armature reaction magnetic field and the rotor excitation magnetic field of the synchronous generator can be approximately considered to be distributed according to the sinusoidal law. The spatial phase difference between them depends on the time phase difference between the no-load electromotive force E0 and the armature current I. The armature reaction magnetic field is also related to the load condition. When the load of the generator is inductive, the armature reaction magnetic field acts as a demagnetizer, which will cause the voltage of the generator to decrease; when the load is capacitive, the armature reaction magnetic field acts as a demagnetizer.The magnetic field acts as a magnet and increases the output voltage of the generator.
Load operating characteristics:
Mainly refers to external characteristics and adjustment characteristics. The external characteristic is the relationship between the generator terminal voltage U and the load current I when the speed is the rated value, the excitation current and the load power factor are constant. The adjustment characteristic is the relationship between the excitation current If and the load current I when the speed and terminal voltage are rated values and the load power factor is constant.
The voltage change rate of a synchronous generator is about 20 to 40%. Generally, industrial and household loads require that the voltage remains basically unchanged. For this reason, as the load current increases, the excitation current must be adjusted accordingly. Although the change trend of the adjustment characteristic is exactly opposite to that of the external characteristic, for inductive and purely resistive loads, it rises, while under capacitive loads, it generally falls.