Working principle of diesel generating sets and working characteristics of generators
Diesel generators mainly operate. The conversion of diesel into electrical energy is similar to the function of windmill conduction. In these aspects, what is the working principle of the generator and its working characteristics? Xiaobian will sort out the principles for everyone. Can help everyone.
In the diesel engine cylinder, the clean air filtered by the air filter is fully mixed with the high-pressure atomized diesel injected by the fuel injection nozzle. Under the squeeze of the piston upward, the volume is reduced, and the temperature is rapidly increased to reach the ignition point of the diesel. Diesel is ignited, the mixed gas burns violently, and the volume expands rapidly, pushing the piston downward, which is called 'work'.
A gasoline engine drives a generator to convert the energy of gasoline into electricity. In the cylinder of a gasoline engine, the mixed gas burns violently, and the volume rapidly expands, pushing the piston to perform work.
Regardless of whether it is a diesel generator or a gasoline generator, the cylinders work in a certain order in turn. The thrust acting on the piston passes through the connecting rod and becomes the force that drives the crankshaft to rotate, thereby driving the crankshaft to rotate. By installing the brushless synchronous alternator coaxially with the crankshaft of the power machine, the rotation of the power machine can be used to drive the rotor of the generator. Using the principle of 'electromagnetic induction', the generator will output the induced electromotive force and generate current through the closed load circuit. .
Working characteristics of diesel generators:
The main characteristics of synchronous generator performance are no-load characteristics and load operation characteristics.
These characteristics are an important basis for users to choose a generator.
No-load characteristics of diesel generators:
When the generator is not connected to the load, the armature current is zero, which is called no-load operation. At this time, the three-phase windings of the motor stator only have no-load electromotive force E0 (three-phase symmetry) induced by the exciting current If, and its size increases with the increase of If. However, due to the saturation phenomenon of the magnetic core of the motor, the two are not proportional. The curve reflecting the relationship between the no-load electromotive force E0 and the exciting current If is called the no-load characteristic of the synchronous generator.
The armature response of a diesel generator set:
When the generator is connected with a symmetrical load, the three-phase current in the armature winding will generate another rotating magnetic field, which is called the armature reaction magnetic field. Its rotation speed is exactly equal to the rotation speed of the rotor, and they both rotate synchronously.
The armature reaction magnetic field and rotor excitation magnetic field of a synchronous generator can both be considered to be distributed according to a sine 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 response magnetic field is also related to the load situation. When the load of the generator is inductive, the armature reaction magnetic field plays a demagnetizing effect, which will cause the voltage of the generator to decrease; when the load is capacitive, the armature reaction magnetic field plays a magnetic assisting effect, which will cause the output voltage of the generator Rise.
Load operation characteristics of diesel generator set:
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 the synchronous generator is about 20 to 40%. General industrial and domestic loads require voltages to remain essentially constant. For this reason, as the load current increases, the excitation current must be adjusted accordingly. Although the changing trend of the adjustment characteristics is exactly the opposite of the external characteristics, for inductive and purely resistive loads, it is increasing, and under capacitive loads, it is generally decreasing.
The above is a brief introduction to the working principle of diesel generating sets and the working characteristics of generators. I hope this knowledge will be helpful to you!
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