@rkmechanical
Profile
Registered: 1 year, 2 months ago
How Induction Generators Work?
Think about it the following scenario: for instance, an AC power source is connected with the terminals of the stator on an induction machine. The magnetic field that is generated by the stator causes the rotor towards it (the machine functions as motor).
Then, if the rotor is speeded up to synchronous speed the use of an acceleration device and the slip is zero, and the torque net would be in the zero range. The rotor's current will be zero as the rotor runs at a synchronous speed.
If the rotor is forced to spin at a speed higher than the synchronous rate then the slip turns negative. The rotor's current is produced to the reverse direction because of the rotor conductors cutting the stator magnetic field.
The generated rotor current generates an electric field that rotates in the rotor that pushes (forces in the opposite direction) into the field of stator. This creates a voltage in the stator that pushes the current flowing out of the windings of the stator against the voltage applied. The machine now functions to function as an induction (asynchronous generator).
Induction generators aren't self-excited device. So, when it is operating as an generator, the machine draws reactive power from the AC energy line, and delivers active power back to the line. Reactive power is required to create a rotating magnetic field. The active power supplied to the lines is related to the speed of slip over the speed of synchronous.
Also Read: What's an Alternator in a Car
Self-Excited Induction Generator
It is obvious that an induction machine requires energy to excite, regardless of whether it operates as a generator or motor. If an induction generator is connected to the grid, it receives the grid's reactive power. But what happens if we want to utilize an induction generator to power loads without the external power source (e.g. grid)?
A capacitor bank may be connected between the terminals of the stator to provide energy to the machine and on to load. When the rotor rotates at a sufficient speed there is a tiny voltage produced across the terminals of the stator due to residual magnetism. In response to this low voltage, a current in the capacitor is generated, which further provides magnetic power through reactive energy.
Induction generators have many applications. Induction generators provide powerful power, even at different speed of rotors. Therefore, they can be used for wind turbines.
Advantages: Asynchronous or induction generators are more durable and do not require a commutator or brush arrangement (as it is required in cases with Synchronous generators).
One of the biggest drawbacks for induction generators is the fact that they consume large amounts of reactive energy.
Also Read: Reaction Turbine
Differentialities between Synchronous and Induction Generators:
Induction generator needs no DC excitation.
Grid-connected Induction generators can only produce electricity when connected to the three-phase supply.
Self-excited Induction generators which do not connect to the grid, they require the power of a reactive source to function, and for this reason parallel capacitors are employed to provide power for reactive purposes.
For an induction generator it is not necessary to synchronize the machine because the machine generates just when its slip turns negative.
Induction generators have rotors with less resistance to decrease slip and loss.
The output frequency and voltage are not affected by speed fluctuations so no voltage regulator is needed. The frequency and voltage is controlled through the power supply system.
As compared to synchronous motors the structure is similar to synchronous motors. It requires less auxiliary equipment. There are no diodes, brushes or collector rings are used.
Maintenance costs are lower.
The size is tiny per KW of output power because of its high energy density.
Contrary to a synchronous generator large power swings don't take the generator out of sync with the network.
Also Read: Composite Materials Definition
Website: https://mechanicaljungle.com/
Forums
Topics Started: 0
Replies Created: 0
Forum Role: Participant