Why does an induction motor need reactive power?

In induction generators, the reactive power required to establish the air gap magnetic flux is provided by a capacitor bank connected to the machine in case of stand-alone system and in case of grid connection it draws reactive power from the grid to maintain its air gap flux.

Why is reactive power generated?

Devices which store energy by virtue of a magnetic field produced by a flow of current are said to absorb reactive power; those which store energy by virtue of electric fields are said to generate reactive power. The flows of Reactive Power on the system will affect Voltage levels.

What is the significance of reactive power?

Reactive power provides the important function of regulating voltage.  If voltage on the system is not high enough, active power cannot be supplied.  Reactive power is used to provide the voltage levels necessary for active power to do useful work.

Why does inductive load absorb reactive power?

The current flowing through capacitors is leading the voltage by 90°. The corresponding current vector is then in opposition to the current vector of inductive loads. This why capacitors are commonly used in the electrical systems, in order to compensate the reactive power absorbed by inductive loads such as motors.

When the induction generator is connected to the load then the reactive power to the induction generator is supplied from?

Isolated Induction Generator It is because it uses a capacitor bank which is connected across its stator terminals as shown in the diagram given below. The function of the capacitor bank is to provide the lagging reactive power to the induction generator as well as load.

Does generator produce reactive power?

Power plant generators generate both active and reactive power whereas capacitors injects the reactive power to maintain the voltage levels.

Where is reactive power used?

Reactive power is used by most types of electrical equipment that uses a magnetic field, such as motors, generators and transformers. It is also required to supply the reactive losses on overhead power transmission lines.

Why does reactive power increase voltage?

Reactive power can cause voltage to rise or to fall depending on which elements are being used for reactive power compensation. So, to maintain voltage stability, decreasing the reactive power causes the voltage to fall and increasing it causes the voltage to rise.

Does induction motor generate reactive power?

No reactive power is supplied by induction machines. Reactive power is the power required for energising the magnetic circuitry of the I.M. In any I.M (generator or motor), the rotor magnetic field always lags behind the stator magnetic field.

What is reactive power control?

Reactive power production and consumption by generators allows the network operator to control voltages throughout their system. The simplest is the fixed power factor. The wind farm is required to operate at a fixed power factor when generating, often equal to 1.

Why is reactive power bad?

Reactive power is unused power that is pushed forth and back. It causes an unwanted current on the transmission line. Consequently, reactive power causes losses on AC transmission lines. By the way, there is reactive power when the angle between voltage and current is pi/2.

Because the rotor field always lags behind the stator field, the induction machine always “consumes” reactive power, regardless of whether it is operating as a generator or a motor. A source of excitation current for magnetizing flux (reactive power) for the stator is still required, to induce rotor current.

What is the working principle of an induction generator?

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.

How does a prime mover work in an induction generator?

In the case of a stand-alone induction generator a prime mover will cause the rotor to move and maintain a constant speed but since insufficient MMF is present (in the form of residual flux) the machine is unable to self-excite and establish a stator voltage required to cause a stator current to flow to develop sufficient MMF.

Why do we need capacitors in an induction generator?

The reactive power drawn by induction generators (particularly of squirrel cage type) has to be compensated by capacitors. However, this problem can be overcome by using doubly fed induction generator or wound rotor induction generator. In these machines, both stator and rotor have three phase AC windings.