1- can operate in generator/ motor mode for both sub/ super-synchronies speed mode with four possible operation conditions
2-A speed variation of ±30% around synchronous speed can be obtained by the use of power converter of 30% of nominal generated power
3-it has not necessarily to be magnetised from the power grid since it can be magnetised from the rotor circuit too
4- the size of the converter is not related to the total generator power but to the selected speed range and hence to the slip power
The principle of the DFIG is that rotor windings are connected to the grid 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). By using the converter to control the rotor currents, it is possible to adjust the active and reactive power fed to the grid from the stator independently of the generator's turning speed.
A shunt generator is a machine with a rotating set of coils of wire embedded in the iron core in its armature (the spinning part), and a 'commutator' and brushes that carry the current from the (spinning) windings on the armature to the stationary external electrical load. It also has a 'field' winding that creates a stationary magnetic field inside the machine, that the armature coils are spun in. As the windings spin, they cut the stationary field and generate an alternating voltage. As well as providing a moving connection to the coils, the commutator and brushes act like a switch, reversing the connections from the coils to the external circuit each time the waveform changes polarity from positive to negative and vice versa. This creates direct current in the external circuit and load. In a shunt generator, the field windings are connected in parallel with the armature ('shunt' is a common term for 'in parallel') and the field gets its power ('excitation') from the armature - the machine is 'self-excited'. A self-excited generator needs a small 'residual field' in the field's iron core so it can generate a small output from the armature when starting, which is fed to the field, boosting the armature output, which is fed to the field.... and so on, until the field iron core saturates with flux, and the field stops strengthening. Shunt generators are the 'workhorse of the small generator market - they are cheap and simple, have an output voltage that 'droops' a little with increasing load, and most shunt generators can safely be short-circuited - this takes the electrical energy away from the field, and the armature can usually develop only a small output current - not enough to damage it.
Horn antenna are typically fed by a section of a waveguide, the waveguide itself is often fed with a short dipole.
Synchronous generators are the majority source of commercial electrical energy. They are commonly used to convert the mechanical power output of steam turbines, gas turbines, reciprocating engines and hydro turbines into electrical power for the grid. (OR) A "synchronous" generator runs at a constant speed and draws its excitation from a power source external or independent of the load or transmission network it is supplying. A synchronous generator has an exciter that enables the synchronous generator to produce its own " reactive" power and to also regulate its voltage. Synchronous generators can operate in parallel with the utility or in "stand-alone" or "island" mode. Synchronous generators require a speed reduction gear
The type of electric motor commonly used in ceiling fans does not make a good electrical generator. It is what is known as an AC (Alternating Current) Shaded-Pole Motor, a type of induction motor. An induction motor resembles a rotating transformer, because the stator (stationary part) is essentially the primary side of the transformer and the rotor (rotating part) is the secondary side. There are no brushes, and no direct electrical connection to the rotor windings. More specifically, these motors are often referred to as "squirrel cage" motors. Squirrel-cage motors have a relatively heavy winding made up of solid bars, usually aluminum or copper, joined at the ends of the rotor. Currents induced into this winding provide the rotor magnetic field. The alternating electromagnetic fields created by the current flowing in the stator windings induce the current into the rotor windings. It is the interaction between the rotor and stator fields that cause the motor to turn. Since power for the rotor is a result of the power fed to the stator, and there is no actual physical electrical connection between the two components, if no current is present when the motor is at rest, none will be produced if it is mechanically driven in an attempt to use it as a generator.
If a self-excited generator lost all its residual magnetism, can it build up an output voltage?
The Doubly Fed Indcution Generator (DFIG) is a very popular machine, since the output of the stator terminals is already at 60hz (no change in voltaje or frequency necessary). The matrix converter is used in the rotor side (wound rotor) in order to control the frequency and voltage magnitud to make the induction machine generate power at a wide range of speeds...
G. Abad has written: 'Doubly fed induction machine' -- subject(s): TECHNOLOGY & ENGINEERING / Power Resources / General, Equipment and supplies, Automatic control, Wind turbines, Mathematical models, Induction generators
The principle of the DFIG is that rotor windings are connected to the grid 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). By using the converter to control the rotor currents, it is possible to adjust the active and reactive power fed to the grid from the stator independently of the generator's turning speed.
basically sensorless scheme estimated the speed using current signal or current sensor without considerartion speed sensor thats reduce the cost of machine and make it more efficient ..basically sensorless scheme can uses sensor only at current signal or sensor at dc link in doubly fed machine,.........................
Fit it. Then find out why it was fed air that was not very dry. The air dryer is usually the cause of generator failure, since the air can also make sticky gunk that will fail the generator.
Fahad H. Al-Ghubari has written: 'Voltage analysis of PWM inverter fed induction motors' -- subject(s): Computer simulation, Electric inverters, Electric motors, Induction, Induction Electric motors, Testing
Ashok Ramchandran has written: 'Frequency-domain, parameter estimation for a brushless, doubly-fed machine' -- subject(s): Brushless Electric motors, Electric motors, Brushless
Wind turbines use rotating blades to capture the kinetic energy of the wind and convert it into mechanical energy. This mechanical energy turns a generator, which produces electricity by converting the mechanical energy into electrical energy through electromagnetic induction. The electricity generated is then fed into the power grid for distribution.
Wind turbine blades are turned by the force of the wind, rotating a shaft connected to a generator. The generator converts the kinetic energy from the spinning shaft into electrical energy, which is then fed into the electrical grid. This process harnesses the power of the wind to generate clean and renewable electricity.
Nuclear fuel - uranium - gets hot and brings water to boil. The steam makes a turbine spin, and the turbine makes an electric generator spin. Electricity from the generator is fed out onto the grid and into peoples homes.
A back feed generator works by connecting directly to a home's electrical system through an inlet box or transfer switch. When there is a power outage, the generator is started and begins producing electricity. This electricity is then fed back into the home's electrical system, providing power to essential appliances and devices.