the rotor’s rotation speed is increased from about 18 revolutions per minute to around 1,800 revolutions per minute, allowing the turbine’s generator to generate AC electricity.
Is a wind turbine a DC or an AC machine?
Although some later versions use a variable frequency AC motor and a three phase AC pump controller that allows them to be powered directly by wind turbines, wind pumping systems are designed to utilise direct current (DC) produced by a wind turbine.
Is it better to use AC or DC for wind turbine generators?
The AC electrical energy should be used to power wind turbines. Because it is simple to operate, according to DC transmission.
Is there a DC motor in a wind turbine?
An electrical generator, as we learned in the previous wind turbine tutorial, is a rotating machine that converts mechanical energy produced by the rotor blades (the prime mover) into electrical energy or power. Faraday’s equations of electromagnetic induction, which dynamically induce an e.m.f. (electro-motive force) into the generator’s coils as it rotates, are used to convert energy. There are many various types of electrical generators, but one that we may employ in a wind power system is the Permanent Magnet DC Generator, also known as the PMDC Generator.
Because there is no structural difference between conventional motors and DC wind turbine generators, permanent magnet direct current (DC) machines can be employed as both. In reality, the same PMDC machine can be driven mechanically as a basic generator to generate an output voltage or electrically as a motor to move a mechanical load. As a result, the permanent magnet DC generator (PMDC generator) is an excellent candidate for use as a simple wind turbine generator.
When a DC machine is connected to a direct current source, the armature rotates at a constant speed specified by the associated supply voltage and magnetic field strength, operating as a “motor” that produces torque. However, if we use rotor blades to mechanically rotate the armature at a higher speed than its designed motor speed, we may effectively turn this DC motor into a DC generator, creating a generated emf output proportionate to its rotational speed and magnetic field strength.
The field winding is usually on the stator and the armature winding is on the rotor in traditional DC machines. They have output coils that rotate with a stationary magnetic field to provide the appropriate magnetic flux. The magnetic field, which controls the power, is supplied by either permanent magnets or an electromagnet and is obtained directly from the armature via carbon brushes.
The stationary or static magnetic field passes through the rotating armature coils, generating an electrical current in the coils. The armature rotates in a permanent magnet DC generator, therefore the entire generated current must travel through a commutator or slip-rings and carbon brushes arrangement to provide electrical power at the output terminals, as depicted.
What kind of electricity is generated by a wind turbine?
Wind turbines absorb kinetic energy from the wind by using blades. Wind creates lift on the blades, which causes the blades to turn (similar to the effect on airplane wings). The blades are attached to a drive shaft that rotates an electric generator, which provides power.
Electrical Works
A Medium Voltage (MV) electrical network, ranging from 10 to 35 kV, connects the turbines. The majority of the time, this network is made up of underground cables, however in some places and nations, overhead wires on wood poles are used. This is less expensive, but it has a stronger visual impact. Crane movement and use can also be restricted by overhead wood pole wires.
The turbine generator voltage is usually classified as ‘low,’ that is, less than 1,000 volts, and is frequently 690 volts.
Although some larger turbines employ a greater generator voltage, around 3 kV, this is insufficient for cost-effective direct connections with other turbines.
As a result, each turbine must have a transformer that can step up to Medium Voltage (MV) and related MV switchgear.
This equipment can be found outside each turbine’s base.
These are known as ‘padmount transformers’ in some countries.
It may be necessary to enclose the equipment in GRP or concrete enclosures, depending on the permitting authorities and local electricity legislation.
These can be erected over transformers or delivered as premade systems with transformers and switchgear already installed.
Many turbines, on the other hand, now feature a transformer as part of the power supply.
In these circumstances, the turbine’s terminal voltage will be MV, ranging from 10 to 35 kV, and it will be able to connect directly to the MV wind farm network without the use of any other equipment.
The MV electrical network transports electricity to a central location (or several points, for a large wind farm).
Figure 4.8 depicts a typical configuration. The focal point in this situation is also a transformer substation, where the voltage is stepped up to high voltage (HV, typically 100 to 150 kV) before being connected to the current power network. Connection to the local MV network may be achievable for small wind farms (up to 30 MW), in which case no substation transformers are required.
Radial ‘feeders’ make up the MV electrical network.
There is no economic basis for providing ring arrangements, unlike industrial power networks.
As a result, if a cable or turbine transformer fails, the switchgear at the substation will disconnect all turbines on that feeder.
If the defect takes a long time to fix, the feeder could be reconfigured to allow all turbines between the substation and the fault to be reconnected.
Figure 4.8 depicts two possible Point of Connection sites (POC).
The POC is the point at which responsibility for ownership and operation of the electrical system passes from the wind farm to the electricity network operator. Definitions of the POC vary by country (it’s also known as the delivery point, point of interconnection, or something similar), but they’re all the same: it’s the point at which responsibility for ownership and operation of the electrical system passes from the wind farm to the electricity network operator.
It is possible to have a more complex division of responsibilities (for example, the wind farm developer may build and install equipment that is then taken over by the network operator), although this is uncommon.
The revenue meters for the wind farm are typically positioned near or at the POC.
The meters may be located on the MV system in some circumstances where the POC is at HV to save money.
In this instance, correction parameters to account for electrical losses in the HV/MV transformer are usually agreed upon.
Figure 4.8 also depicts a proposed Point of Common Coupling position (PCC).
This is the point where other customers are (or may be) linked.
As a result, it is at this phase that the impact of the wind farm on the electrical grid should be assessed.
Voltage step variations, voltage flicker, and harmonic currents are examples of these phenomena.
Part II: Grid Integration delves deeper into grid concerns.
Frequently, the PCC and the POC are the same.
The following are the design requirements for the wind farm electrical system:
- It must comply with local electrical safety regulations and be capable of safe operation.
- It must strike the best possible balance between capital expenditures, operating costs (mostly electrical losses), and reliability.
- It must ensure that the wind farm meets the power network operator’s technical criteria.
The connection agreement, or a ‘Grid Code’ or comparable document, specifies the technical requirements of the power network operator. Part II delves deeper into this topic.
Do hydroelectric dams generate AC or DC electricity?
When you put a toaster or stereo into a wall outlet, power is available right away to toast your bread or play music. Have you ever thought about how power goes from a hydroelectric generating facility to your wall socket? We need to look at those electrons in our aluminum wire again to get the answer.
Remember that electrons are pushed between atoms by magnets passing across a wire or coil of wire. The electrons transfer a charge to the next atom as they leap. The electron of the following atom leaps when it takes the charge. The magnets start a chain reaction that moves the wire down. Because aluminum is a conductor it conducts electricity the electric energy goes along the wire. Manitoba Hydro has a large network of wires of various sizes that carry electricity across the province and to your home. However, that is only half of the solution.
Hydroelectric producing units on the Nelson River in northern Manitoba supply roughly 70% of Manitoba’s electricity. As a result, we must transmit the sustainable hydroelectric power it creates over 1,000 kilometers to southern Manitoba, where the majority of people live and work, as well as the majority of enterprises.
To carry power from the north more effectively, Manitoba Hydro use high voltage direct current (HVDC) technology. Electric current that flows in only one direction is known as direct current (DC). It’s the kind of power that batteries in cameras, flashlights, and automobiles produce. Alternating current (AC) is the type of energy used in your home. It is an electric current that reverses direction 60 times per second. The advantage of DC is that it loses far less power over long distances than AC.
DC transmission uses a higher voltage to maximize energy transmission and reduce losses. Let’s compare electricity flowing via a wire to water running through a pipe to see why. A big diameter wire may transport enormous amounts of electricity in the same way that a large diameter pipe can transport large amounts of water. By increasing the pressure, large amounts of water can be carried via a small diameter pipe, such as a garden hose. Similarly, boosting the voltage allows more electricity to be transported through a small diameter wire.
To bring electricity from the north, we erected three HVDC transmission lines known as Bipole I, Bipole II, and Bipole III. The electricity you use in your home has a voltage of 120 volts AC. The HVDC wires carry power with a force of 500,000 volts or 500 kV.
Assume your home’s electricity has the same force as a baseball thrown at you at 100 kilometers per hour. The electricity on the HVDC line would have a force almost 4,000 times greater.
Hydroelectric power plants generate AC energy at a voltage of roughly 25 kV. To reduce power losses over long distances, it must be converted to DC and transmitted at an even greater voltage. The Henday, Radisson, and Keewatinohk converter stations near Gillam, Manitoba, perform this conversion.
After being converted from AC to DC, the electricity is sent south to the Dorsey and Riel converter plants outside of Winnipeg. Refrigerators, TVs, laptops, and other gadgets run on AC energy, which is converted back to DC at Dorsey and Riel before being delivered to your home. AC transmission lines connect Dorsey and Riel to the rest of southern Manitoba, as well as the northern United States, Saskatchewan, and northwestern Ontario.
The electricity is transported to substations around the province by high-voltage AC lines. These substations house equipment that converts voltages to lower levels, turns on or off a line’s current, and analyzes and measures electricity.
Electricity is converted from high voltage to low voltage using the same principle as it is generated. A fluctuating current in a second coil can be caused by the magnetic field of a coil of wire carrying an alternating, or fluctuating, current. Two independent wire coils are wrapped around a magnetic iron core in a transformer. The magnetic field of the iron core fluctuates due to the electricity in the first coil of wire. After passing through the iron core, the fluctuation electrifies the second coil of wire. The electricity will have half the voltage if the second coil of wire has half as many turns. The voltage will be doubled if the second coil has twice as many spins as the first.
Electricity travels from substations to transformers through overhead lines or underground cables, completing the voltage drop. For overhead lines, these transformers are positioned towards the top of hydro poles, while for underground lines, they are located at ground level.
Electricity runs through a line from the pole into your home, first to the meter and then to the main switch. After that, the cables are routed to a distribution panel. Circuits within the walls then lead to power outlets and light fixtures.
