Synchronous motor, like induction motors (ie asynchronous motor), is a common AC motor. Synchronous motor is the heart of the power system. It is a kind of component that combines rotation and static, electromagnetic change and mechanical motion to realize the transformation of electrical energy and mechanical energy. Its dynamic performance is very complex, and its dynamic performance is dynamic to the whole power system. Performance has a huge impact.
The characteristic is: in steady state operation, there is a constant relationship between the rotor speed and the grid frequency n=ns=60f/p, where f is the grid frequency, p is the pole pair of the motor, and ns is called the synchronous speed. If the frequency of the grid does not change, the speed of the synchronous motor at steady state is constant and independent of the magnitude of the load. Synchronous motors are classified into synchronous generators and synchronous motors. The AC machine in the power plant is dominated by synchronous generators.
There are three main modes of operation for synchronous motors: generators, motors, and compensators.
Running as a generator is the most important mode of operation for synchronous motors.
Operating as a motor is another important mode of operation for synchronous motors. The power factor of the synchronous motor can be adjusted. When no speed regulation is required, the application of a large synchronous motor can improve the operating efficiency. Small synchronous motors are beginning to find more applications in variable frequency speed control systems.
The synchronous motor can also be connected to the grid as a synchronous compensator. At this time, the motor does not carry any mechanical load, and the excitation current in the rotor is adjusted to send the required inductive or capacitive reactive power to the grid to achieve the purpose of improving the power factor of the grid or adjusting the voltage of the grid.
Synchronous generators, like other types of rotating electrical machines, consist of a fixed stator and a rotatable rotor. Generally divided into transition synchronous motor and pivot synchronous motor.
The most commonly used is a synchronous synchronous generator. The inner circumference of the stator core is evenly distributed with the stator slots, and the three-phase symmetric windings arranged regularly are embedded in the slots. The stator of such a synchronous machine is also called an armature, and the stator core and winding are also called an armature core and an armature winding.
The rotor core is provided with a pair of magnetic poles of a certain shape, and a magnetic winding is wound around the magnetic pole. When a direct current is applied, a magnetic field between the polar phases is formed in the air gap of the motor, which is called an excitation magnetic field (also called a main magnetic field). Magnetic field, rotor magnetic field).
The prime mover drags the rotor to rotate (the mechanical energy is input to the motor), and the excitation magnetic field between the polar phases rotates with the shaft and sequentially cuts the stator phase windings (corresponding to the conductors of the windings to cut the excitation magnetic field).
