Principle of operation. An induction generator produces electrical power when its rotor is turned faster than the synchronous speed. This causes the stator flux to induce rotor currents, which create a rotor flux with magnetic polarity opposite to stator..
Then, why do induction generators need reactive power?
An induction generator essentially needs a lagging current (inductive current) to magnetise the core. Therefore it draws reactive power from the grid (to which it is connected to feed real power). The reactive power drawn by induction generators (particularly of squirrel cage type) has to be compensated by capacitors.
why capacitor is used in induction generator? The function of the capacitor bank is to provide the lagging reactive power to the induction generator as well as load. There is generation of small terminal voltage oa (as in figure given below) across the stator terminal due the residual magnetism when the rotor of the induction machine runs at the required speed.
what is the difference between induction motor and induction generator?
An induction generator looks a lot like an induction motor used in industry and it is, the difference is when the machine is rotated faster than its normal operating speed, an induction generator produces AC electricity.
Do wind turbines generate AC or DC?
The generator in a wind turbine produces alternating current (AC) electricity. Some turbines drive an AC/AC converter—which converts the AC to direct current (DC) with a rectifier and then back to AC with an inverter—in order to match the frequency and phase of the grid.
Related Question Answers
Why is it called synchronous generator?
A synchronous generator is called “synchronous” because the waveform of the generated voltage is synchronized with the rotation of the generator. Each peak of the sinusoidal waveform corresponds to a physical position of the rotor. The magnetic field of the rotor is supplied by direct current or permanent magnets.Why induction generator is called asynchronous generator?
Induction generators are also called as asynchronous generators. In an induction motor, the rotor rotates because of slip (i.e. relative velocity between the rotating magnetic field and the rotor). Rotor tries to catch up the synchronously rotating field of the stator but never succeeds.Can I use an electric motor as a generator?
Yes, you can use your motor as generator. Working of electric motor:-When electricity is passed through a coil in a magnetic field then the magnetic force produces a torque which turns the motor. In small DC Motors permanent magnets are used to create the magnetic field.so,you can use it as a generator.Can you use a 3 phase motor as a generator?
3 phase motor used as generator. No it will not act as an alternator. To generate electricity you have to move wires through an electromagnetic field, or move the field past the wires.. There is no such field in an ordinary three phase or single phase AC motor which is just being spun with a petrol or diesel motor.How is reactive power generated?
Reactive power is mainly produced by Synchronous Generators through rotor field current (Generator Excitation). The larger the demand of reactive power in system is, the larger should be the Generator field current to meet that demand.How do generators work?
Generators don't actually create electricity. Instead, they convert mechanical or chemical energy into electrical energy. They do this by capturing the power of motion and turning it into electrical energy by forcing electrons from the external source through an electrical circuit.What is synchronous speed?
In a motor, synchronous speed is the speed at which the magnetic field rotates. Depending on motor design, the actual mechanical speed may be equivalent (synchronous motor) or slightly smaller (asynchronous motor). The synchronous speed is a function of:The electrical frequency used, typically 60 Hz or 50 Hz.What is meant by induction motor?
Definition of induction motor. : an alternating-current motor in which torque is produced by the reaction between a varying magnetic field generated in the stator and the current induced in the coils of the rotor.What is the difference between induction motor and synchronous motor?
A synchronous motor is a doubly excited machine, whereas an induction motor is a single excited machine. In case of Synchronous motor its armature winding is energized from an AC source and its field winding from a DC source, whereas in case of Induction motor its stator winding is energized from an AC source.How induction motor is used as a generator?
We know that induction motor works as a generator that means they converts the mechanical energy it receives into electrical energy and this energy is received by the stator. For creating its own magnetic field it takes reactive power and supply active power.What is the slip?
Slip can be defined as the difference between the flux speed (Ns) and the rotor speed (N). Speed of the rotor of an induction motor is always less than its synchronous speed. It is usually expressed as a percentage of synchronous speed (Ns) and represented by the symbol 'S'.Why synchronous generator is doubly excited?
The magnetic field created by the armature currents rotates at the same speed as that created by the field current on the rotor, which is rotating at the synchronous speed, and a steady torque results. Synchronous Generator is a doubly excited machine .What RPM do generators run at?
3600 RPM
Is an alternator an induction motor?
3 phase IM is a motor-->converts electrical energy into mechanical energy whereas alternator is a generator--> converts mechanical energy into electrical energy. Construction of induction motor is less complicated as it does not require brushes and slip ring arrangement.What happens when induction motor runs at synchronous speed?
The induction motor always runs at speed less than its synchronous speed. Due to the lag between the flux current in the rotor and the flux current in the stator, the rotor will never reach its rotating magnetic field speed (i.e. the synchronous speed).What is an Isalternator?
An alternator is an electrical generator that converts mechanical energy to electrical energy in the form of alternating current. In principle, any AC electrical generator can be called an alternator, but usually the term refers to small rotating machines driven by automotive and other internal combustion engines.How does a doubly fed induction generator work?
The principle of the DFIG is that stator windings are connected to the grid and rotor winding are connected to the converter via slip rings and back-to-back voltage source converter that controls both the rotor and the grid currents. Thus rotor frequency can freely differ from the grid frequency (50 or 60 Hz).What generator is used in wind turbines?
induction generator
What is doubly fed induction generator?
A Doubly Fed Induction generator as its name suggests is a 3 phase induction generator where both the rotor and stator windings are fed with 3 phase AC signal. It also consists of a multiphase slip ring assembly to transfer power to the rotor. It is typically used to generate electricity in wind turbine generators. 
