Double fed induction generator

Double Fed induction generator for producing electricity using wind power A 3 phase induction generator called Double Fed induction generator where both the rotor and the stator windings are connected with 3 phase Ac signals. On both the rotor and the stator bodies you can find the multi phase windings connected to them. For transferring power to the rotors it consists of multiphase slip ring assembly. The main application of this device is used for generating electricity in wind turbine generators.

Let us have a brief idea about power generation before going into the details of Double Fed induction motor.

As we all know that one of the most renewable sources of energy is wind energy. The electricity is generated with the rotation of large turbines and the blowing of winds.

4 Types of Wind Generator Generators: Type 1: It has a direct connection to the power grid to the squirrel cage generator. The wind speed used over here is quite less.

Type 2: Before being connected to the power grid there is an AC-DC-AC converter to pass on.

Type 3: Here the rotors speed is adjusted using a rheostat and it also consist of wound rotor induction with a direct connection to the power grid.

Type 4: Back to back converters are used for adjusting the rotor speed in the Double Fed Induction Generator which has a direct connection to the power grid.

Generate electricity from the wind energy using Double Fed Induction Generator There are three phase wound rotor and three phase wound stator in DFIG. A 3 phase AC current is fed to the

rotors for inducing an AC current to the rotor windings. A mechanical force is exerted on the rotor as the wind turbines rotates. An induction of ac current is caused in the stator windings as a result of constant magnetic flux passing through the stator windings. The frequency of ac current fed to the rotor windings and the speed of the rotor governs the speed of the rotation of the magnetic field.

For producing ac signals of constant frequency the basic requirement of electricity generation used is wind energy. The rotor windings that receive the ac signal has to be adjusted in its frequency of the signal to achieve this.

As the rotor ac signal increases and the rotor speed decreases, the polarity is positive and is vice versa. Stator signal frequency should be equal to the network line frequency and that is how the rotor signal is to be adjusted. By adjusting the rotor windings in the same direction of the generator or the opposite direction of the generator rotor this can be achieved.

Wind Power Generation System

The whole program comprises of the following components: A Wind Turbine: It is a fan consisting of 3 blades that can rotate as the wind strikes. The rotation axis should be aligned with the wind.

Gear Box: For converting energy from one device to another a mechanical method is used with high precision.

Dual

Fed

Induction

Generator:

For

converting

mechanical energy to electrical energy with variable frequency.

Grid Side Converter: This AC-DC converter is used for providing a regulated DC voltage and is used to maintain a constant DC link voltage.

Rotor Side Converter: For providing controlled Ac voltage to the rotor this DC-AC inverter is used.

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