Generators used in Wind Power Generation

Generators are of varied categories in the mechanical worlds. The differences in the mechanistic categories of the generators originate from the fact that there are varying differences and makes in the market. The different roles and responsibilities that are accrued to the materials and machines make them to take differing protocols of creation and manufacture in the market. This piece of paper will explore on the differences and similarities of three types of generators used in wind power generators. These generators are Permanent magnet synchronous generator, Squirrel cage induction generator, and doubly fed induction generator.

Don't use plagiarized sources. Get Your Custom Essay on
Generators used in Wind Power Term Paper
Just from $13/Page
Order Essay

Comparison of Generators used in Wind Power Generation

Doubly fed induction generator

Doubly fed induction generator is electric motors that make part of the power generation mechanics in the world technology. The Doubly fed induction generator has windings that appear on both sides of the rotating and stationary parts. The windings are concerned with transfer of power that comes between the electric system and the shaft. The stator winding has a number of connections to the three-phase rotor and three-phase grid. The frequency of the converter is vital to the general functionality of the machine. The Doubly fed induction generator machines have the sole purpose of varying speeds of the shaft of the machine (Abad, 2011).

The wound rotor with a double electric machine feeding it is the simple electric machine functioning with rated torque to double-synchronous velocity for a given occurrence of excitation. This happens with pole-pair doubly fed machines while the stator and rotor are fixed. Within in high power applications, three or two pole-pairs of the machines become used. The high speed fixed with rated torque. This means that these machines have the capacity to offer lower cost per kilowatts, higher density of power and higher frequency unlike other machines in the field.

There is a capacity to change any multiple electric machine to fit the different uses within the power generation phases. Unlike other machines, doubly fed induction generator has the capacity to be changed and be converted into rotor that is wound and with doubly fed electric motor. This offers more advantage to the use of the machine even with single fed systems and operation in the generation of power in powerhouses (Ackermann, 2012).

As done n many other machines all machines with electronic purposes, doubly fed machines make use of the torque current and magnetic flux in order to produce torque. Permanent magnets are not therein such a machine. The machine is extremely beneficial when it comes to use of magnetic current that is used to generate the magnetic flux. The generation of the magnetic flux is useful when it comes to management of the available energy. The energy released is used within the system and hence released for other external purposes in the environment. The magnetizing current and the torque current are orthogonal in nature. This means that they do not sum up to the general parameters of performance of the machine. Rather, the influence of the orthogonal nature makes the entire machine to be significant and different from the others in the world. The rotor windings are used as gadgets that help to generate power. This occurs unlike in the other apparatus used to generate some current in the environment (Lab-Volt, 2011).

The synchronous speed has to take an example of a direct current that is common among many ordinary synchronous speeds. The shaft speed can operate above or below the synchronous speed. This is where the current by the rotor has to take the form of an alternating current while at slip frequency. Such n issue means that the winding frequency needs the services of a rotor power that will be used to magnetize the non-synchronous operation.

Torque is produced and will be required to monitor the movement of the rotor current. Te rotor current that will be produced is based on the measurements of the torque as the producing component and the other mechanistic operations that happen within the machine. This operation is unlike in other machines that are used to generate power and electricity.

There is a steady proportionality between the degree of the voltage by the rotor and the difference that exist between synchronous speed and the general speed of the machine. When the machine is stopped, the regularity of the stator is similar to the overall frequency elaborated by the machine. The proportion of the rotor and stator winding is very instrumental in many phases of operation. The characteristics of the machine that are similar to the general perception of the machine or the generator are revealed. This happens mostly during the transients in the grid stages (Soloumah, 2009).

The voltage current within the rotor is responsible for a number of functionalities within the machine. They are part of the elements that are directed at reflecting the innate desires and capabilities within the speed and torque of the machine at hand. When the speed of the rotor or the machine is being operated like the motor, then the rotor will elicit generation of authority if the speed is under the synchronous speed of the appliance. This is the sub-synchronous functionality of the machine. When the rotor has a rated torque, another power (the rated active power) will be manifested and used within the machine (Flannery, 2008).

The rotor and the frequency are described as per the operations of their speeds and operation within a normalized avenue of operation. Therefore, the operation of the machine reveals it efficiency. The efficiency of this machine is not as good like those of other machines generating power. When at low speeds, many losses are realized from the amount of current that is required and the amount of voltage that makes the requirement for the production of mechanical power at little and large volumes.

At some instance, the general operation of the machine is foreseen to be established at speeds that are above the synchronous speed. The power is generated and realized through the rotor and the stator mechanistic purposes. This means that the good organization of the machine is calculated from the ratio of the power taken by the machine to the power that was produced initially by the machine. In this regard, it is important to take into consideration the amount of the losses in power control electronic equipment. Nonetheless, the occurrence converter of the machine that is fed twice is supposed to be in full control of only 50% or a smaller amount of the supremacy of the contraption. This means that the amount of the machines that are fed once in frequency is supposed to be realized from the 100% operation of the machine in one stage of production.

In general, efficiency of any machine I calculated from the proportion between the productivity powers to the contribution power. This means that the magnetic core competence of a wound rotor doubly fed machine, with two windings in has sets of loss but illustrates double the control for a given occurrence and voltage of operation. This can be compared to the captivating core good organization of undying magnet machinery with one winding but without magnetizing energy. When touched with a number of electronic controllers with low power, much relevance and evidence are given by the machine to the environment. There are other situations that make the machine operate as a generator. Moreover, the machine has the entire capability to operate as a synchronous speeding machine while producing the required amount of energy. When the machine is operating at a super synchronous speed, the stator and the rotor act in a way to produce power that is supplied to the grid (Earnest & Wizelius, 2011).

The general rating current is required by the rotor converter and is stated by the utmost active current produced by the torque current. This is also produced within the similar avenues of utmost reactive current required to bring about magnetization of the machine while in immense use.

Twice-fed electric machines break the others in super synchronous speeds. This is because they have the capability to operate at constant torque within double-synchronous speeds. This happens if all the active windings are rated within the half of the total synchronous operation of the machine. The general productivity and operation of the machine is done within half the sub-synchronous probabilities of the machine while in operation (Tong, 2010).

Machines that have double fed operations in do not produce enough power together with rated torque that is more continuous in nature. These are machines that dwell within the notion of fighting for production of power through the single feedings from the entire segments of the machine. The generation of the magnetic flux plays a critical role in alleviating for the generation and use of power in every sector of operation within the machine. The generation of the magnetic flux is not weakened by the supposed operations that dictate the general productivity and efficiency of the machine while in the field of use (Datta & Ranganathan, 2002). The little occasion utmost torque of a rotor twice-fed electric machine is of higher frequencies and capabilities unlike other machines used within the frames of generating power in the society. Several avenues of operation are used within this notion of realizing the existence and consequence of having a firm body of generating any amount of energy to be used in the field. In order to foster equitable management of the practices and operations of producing energy in the field, there is much reputation of the available facilities to be used as capable parameters in designing the amount of energy needed for production in the field (Flannery, 2008).

Example of the machine

Squirrel cage induction generator

In this machine, the field windings are used within the stator of the motor and the rotary movement of the field of magnetism in the rotor. The relational motion that exists between the field of magnetism and movement of the rotor produces an induced electric current within the bars of conduction in the available fields. In revolve, the currents lengthwise in the conductors changes in a manner similar to the magnetic behavior of the motor (Eremia, 2013). This results in the creation or production of a force that appears to be acting at a tangent orthogonal to the rotor. This force is a subject matter to the generation of a torque in the shaft. The rotor becomes one of the factors of operation that are used within the stakes of the magnetic field but within the notion of lower rates in rotation. The lower rates of rotation result in what is termed as slip and increase in the overall amounts of loads (Rashid, 2010).

The functionality of many conductors is found within the range of torque functionalities. The lengths of the available torques and other gadgets of operation are reflected within a single mechanistic platform of reflection on the fluctuations of torque and their resultant speeds. Reducing the production of the rotor ensures the existence of few instances of a large production of noise and many related features in the production avenues. The skewing of the conductors is done solely to reduce the instances and chances of noise pollution in the process of producing energy in the field (Earnest & Wizelius, 2011).

The function of the iron core is related to the magnetic fields that happen through the rotor conductors. This happens because the magnetic field in the rotor is alternating with time. The core aims are done within the facet of construction of the transformers in order to reduce energy loses that occur within this category of operation in the field. The facet of operation within this category of the machines is done with the use of thin laminations, separated by varnish insulation, to reduce eddy currents circulating in the core. The material I made of a material of low carbon, but with high silicon iron, that has a number of resistivity of pure iron in them (Ackermann, 2012).

This similar basic design is used within the single-phase and three-phase motors over a wide range of sizes. The category of rotors for three-phase will have variations in depth and shape of bars. This is done in order to suit the design classification. Within the efficiency parameters of this material, thick bars have good torque and are efficient at low slip. This happens because of the fact that they have lower conductivity to the EMF. When the slip of the material increases, skin effect starts to reduce the effective depth and increases the resistance. This matter has its own effects as it results in reduced efficiency but still maintaining torque (Kaz-mierkowski et al., 2002).

Effectiveness and differences in their topologies

A single-phase motor and a copper pipe are supposed to be used in order to have a clear demonstration of the stator . When a good amount of AC power is supplied to the stator, there is a development of an alternating magnetic field that revolves around the stator. In case a copper pipe is inserted inside the stator, there occurs a new facet of induction in the induced current pipe. This current works with production of the current that produces another magnetic field. The relationship that is established between the stator-revolving field and motor induced field leads to the production of a torque and thus rotation. This rotation is very instrumental in the general generation of current or power in the field (Flannery, 2008).

Diagram of Squirrel cage induction generator

Permanent magnet synchronous generator

A permanent magnet synchronous generator uses the principle of the excitation. This is one of the fields where the excitation field is provided by a permanent magnet and not the coil as in other machines. Several synchronous generators are the majority source of marketable power (Pyrhonen et al., 2008). These gadgets are commonly used to convert the mechanical power output of many sources like gas turbines, steam turbines, and other types of engines like reciprocating engines, hydro turbines, and wind turbines into electrical power for the grid. These materials are referred to as synchronous generators. The reason or explanation behind this notion is because of the speed of the rotor that must always match the supply frequency (Rashid, 2010).

Within the normalized avenue of permanent magnet generator, the magnetic field within the rotor is produced through the influences of the permanent magnets. There are other categories of generators that use electromagnets to manufacture electric forces within the rotor windings (Earnest & Wizelius, 2011). The direct current within the rotor field winding is determined through a slip-ring congregation or manufactured by a brushless exciter on the same shaft. This categorical facet differentiates between the several facets of performance within the three major types of power generation mechanisms (Kinnunen & Lappeenranta, 2007).

The Permanent magnet generators within this category of the machine do not need a DC supply for the excitation circuit. Moreover, it does not require the need for slip rings and contact brushes. Nonetheless, large permanent magnets are pricey. This puts restrictions to the economic rating of the machine as compared to the other categories of the machines. The flux density of high performance permanent magnets is of little effect. The air gap flux cannot be controlled. This means that the voltage of the machine cannot be regulated with ease. This is another feature that states the difference between the two categories of the machines in the market (Gieras et al., 2008).

Diagram of Permanent magnet synchronous generator

Conclusion

Generators used in power generation appliances are of varying categories. From the clear understanding of the varying levels of performances in the three generators, there are some of the basic differences in their mechanistic properties and workability in the field. The Permanent magnet synchronous generator has the advantage of being flexible in its use in the field. Large voltages of power can be generated from this device. Moreover, the machine is effective, efficient, and covers a large degree of performance in the field of use. Unlike the other generators, the permanent magnet synchronous generator is multifaceted in nature. Nonetheless, it is highly consuming when it comes to management of the other features of use and management in the field of power production. The Squirrel cage induction generator has the advantage of being simple and easy in its use. Nonetheless, it is quite expensive and does not meet the diverse requirements of being fundamental in energy production in the market. On the other hand, the doubly fed induction generator is the best used in the field. It produces energy in continuous motions and mechanisms that are within the construct of many power generation plants. It beats the other generators in the field. Nonetheless, it is quite expensive for normal companies and organizations in order to afford and make use of them in the field of energy production.

References

Abad, G. (2011). Doubly fed induction machine: Modeling and control for wind energy generation applications. Hoboken, NJ: Wiley.

Ackermann, T. (2012). Wind power in power systems. Hoboken: John Wiley & Sons.

Datta, R. & Ranganathan, V.T. (2002). Variable-speed wind power generation using doubly fed wound rotor induction machine — a comparison with alternative schemes. IEEE

Power & Energy Society Volume: 17, Issue: 3:: 414 — 421

Earnest, J. & Wizelius, T. (2011). Wind power plants and project development. PHI

Learning Pvt. Ltd.

Earnest, J., & Wizelius, T. (2011). Wind power plants and project development. New Delhi:

PHI Learning.

Eremia, M. (2013). Handbook of Electrical Power System Dynamics. New York: Wiley.

Flannery, P.S. (2008). Doubly fed induction generator wind turbines with series grid side converter for robust voltage sag ride-through.

Gieras, J.F., Wang, R.-J., & Kamper, M.J. (2008). Axial flux permanent magnet brushless machines. Dordrecht: Springer.

Kaz-mierkowski, M.P., Krishnan, R., & Blaabjerg, F. (2002). Control in power electronics:

Selected problems. Amsterdam: Academic Press.

Kinnunen, J., & Lappeenranta teknillinen yliopisto. (2007). Direct-online axial flux permanent magnet synchronous generator static and dynamic performance.

Lappeenranta: Lappeenranta University of Technology.

Lab-Volt (Quebec) Ltd. (2011). Principles of doubly-fed induction generators (DFIG):

Student manual. Que-bec: Lab-Volt.

Pyrhonen, J., Jokinen, T., Hrabovcova?, V., & Wiley InterScience (Online service). (2008).

Design of rotating electrical machines. Chichester, U.K: Wiley.

Rashid, M. (2010). POWER ELECTRONICS HANDBOOK. Burlington: Elsevier Science.

Soloumah, H.M.J. (2009). Doubly-fed induction generator used in wind energy. Ottawa:

Library and Archives Canada = Bibliothe-que et Archives Canada.

Tong, W. (2010). Wind Power Generation and Wind Turbine Design. WIT Press