Synchronous generators are often utilized in variable-speed wind turbine applications because of their low rotational synchronous speeds, which create grid-frequency voltage. Variable speed synchronous generators will produce variable voltage and variable frequency power.
Why Synchronous Generator Is Not Self-Starting?
Synchronous generators do not generally self-start. You’ll need to use another method, such as a little engine attached to the shaft, to get it close to running speed.
Some design characteristics make the procedure easier by beginning the synchronous motor as an induction motor and then keeping it in synchronism after it catches up with speed.
Synchronous motors are not self-starting after a certain size. This feature is related to the rotor’s inertia; it cannot follow the rotation of the stator’s magnetic field in real-time.
The field winding is stimulated when the rotor approaches synchronous speed, and the motor pulls into synchronization.
What Is A Synchronous Generator, And How Does It Work?
Electrical motors are electromechanical devices that transform electrical energy into mechanical energy. Single-phase and three-phase motors have been categorized based on the type of input.
Synchronous and induction motors are the two most popular types of three-phase motors. An electrical field is created when three-phase electric wires are positioned in specific geometrical configurations, such as at an angle to one another. The synchronous speed is the rotational speed of the revolving magnetic field.
If an electromagnet is present in this revolving magnetic field, it is magnetically locked to it and rotates at the same rate as the field. This is why these motors are known as synchronous motors because the rotor of the motor rotates at the same speed as the revolving magnetic field.
What Is The Purpose Of Using A Synchronous Generator?
The synchronous electrical generator (sometimes known as an alternator) is part of the electric rotating machine family.
In a brushless (spinning rectifier) variant, this equipment is durable, easy to operate, and nearly maintenance-free.
It creates electrical power at a frequency proportional to the rotor’s speed, resulting in synchronous electrical and mechanical speeds, which explains the machine’s name.
In terms of active power, it is capable of converting mechanical energy into electric energy. A synchronous generator can generate reactive power which means it can generate and control the output voltage.
The vast majority of power generators are synchronous generators. They have a magnetic field of their own. It could be a permanent magnet or a field winding with a magnetizing current to provide the required magnetic field.
The term synchronous comes from the fact that the magnetic field synchronizes the frequency of the generated voltage and the mechanical speed (similar to a magnetic gear). To put it another way, the frequency generated is an integer multiple of the rotational speed. This factor is determined by the number of magnetic poles.
What Happens When A Synchronous Motor Becomes A Synchronous Generator?
When the load turns a synchronous motor harder than the motor turns the load, the motor is theoretically acting as a generator.
A water pump comparison is the simplest example: a synchronous motor turns a water pump at a consistent speed to give a constant velocity of flow from a reservoir to a customer. Let’s pretend the reservoir opens the gate a little wider or sends more water through the same conduit.
The water flow will accelerate through the pipe until it reaches the synchronous motor-driven pump; because synchronous motors can only function at synchronous speeds, the water flow will push harder against the pump and motor than the motor is pushing.
If the water pushes hard enough, the motor will generate power and push that current back into the grid.
Why Don’t We Use Synchronous Generator As An Induction Generator Instead?
A synchronous Generator cannot be used as an induction generator. The circulating current will heat the core and may damage the insulations, making this operation disastrous.
The reactive power flow has also changed significantly. A Synchronous Generator that was previously creating lagging power is now absorbing lagging power and generating leading power. These abrupt adjustments would undoubtedly cause network disruptions.
Failure of the field does not imply that the rotor magnetic field is not present. The gadget creates a magnetic field by drawing reactive energy from the Grid. The circulating rotor currents form this field.
In industries, the Generator Protection system prevents these situations by isolating the generator from the grid as soon as it detects a fault.
Related Questions
What are some examples of synchronous generator applications?
The majority of commercial electrical energy is generated by synchronous generators. Steam turbines, gas turbines, reciprocating engines, and hydro turbines are all routinely utilized to transform mechanical power into electrical power for the grid. This generator type is also used in some wind turbine designs.
What is the synchronous motor’s self-control mode?
The supply frequency is altered in a self-controlled mode such that the synchronous speed is the same as the rotor speed. As a result, the rotor is unable to break out of the slide, and hunting eliminations are eliminated. The motor does not require a damper winding in this mode of operation.
Conclusion
So, now you get to know that synchronous generators are not self-starting and also got familiar with the phenomenon behind it. All this process relies on the working phenomenon of the synchronous machine where you need to do some additional changes in order to get the required synchronous speed.