- Wind turbine classification
- Advantages and disadvantages of “wind turbines”
- Homemade wind generators
- Generalized project of a home wind turbine
- About generators for home “wind turbines”
- Vertical-axis homemade “windmill”
- Making the Savonius rotor
- Motor connection and mast mounting
- Voltage controller (simple charger)
- Horizontal-axial windy electrical installation
- Manufacturing of a horizontal-axis “wind turbine”
- Combined wind turbines
- Calculating the power of a home wind farm
One of the most affordable options for using renewable energy sources is the use of wind energy. How to independently make a calculation, assemble and install a wind turbine, read this article.
Wind turbine classification
Installations are classified based on the following wind turbine criteria:
- the location of the axis of rotation;
- number of blades;
- material of elements;
- screw pitch.
Wind turbines, as a rule, have a design with a horizontal and vertical axis of rotation.
Horizontal-axis version – propeller design with one, two, three or more blades. This is the most common version of air power plants due to its high efficiency..
Execution with a vertical axis – orthogonal and carousel structures on the example of Darrieus and Savonius rotors. The last two concepts should be clarified, since both have some significance in the design of wind generators..
The Darrieus rotor is an orthogonal design of a wind turbine, where aerodynamic blades (two or more) are located symmetrically to each other at a certain distance and are fixed on radial beams. A rather complex version of the wind turbine, requiring careful aerodynamic design of the blades.
The Savonius rotor is a carousel-type wind turbine design, where two semi-cylindrical blades are located one against the other, forming a sinusoidal shape as a whole. The efficiency of the structures is not high (about 15%), but it can be almost doubled if the blades are placed in the direction of the wave not horizontally, but vertically and use a multi-tiered design with an angular displacement of each pair of blades relative to other pairs.
Advantages and disadvantages of “wind turbines”
The advantages of these devices are obvious, especially when applied to domestic conditions. Users of “wind turbines” actually get the opportunity to reproduce free electricity, apart from the small costs of construction and maintenance. However, the disadvantages of wind turbines are also obvious..
So, in order to achieve the efficient operation of the installation, the conditions for the stability of wind flows must be met. A person cannot create such conditions. This is purely the prerogative of nature. Another, but already technical drawback, is the low quality of the generated electricity, as a result of which it is necessary to supplement the system with expensive electrical modules (multipliers, chargers, batteries, converters, stabilizers).
The advantages and disadvantages in terms of the features of each of the wind turbine modifications, perhaps, balance at zero. If horizontal-axial modifications are characterized by high efficiency values, then for stable operation they require the use of wind flow direction controllers and hurricane wind protection devices. Vertical-axial modifications have low efficiency, but they work stably without a wind direction tracking mechanism. At the same time, such wind turbines are distinguished by a low noise level, exclude the effect of “runaway” in conditions of strong winds, and are quite compact.
Homemade wind generators
Making a “windmill” with your own hands is a completely solvable task. Moreover, a constructive and rational approach to business will help to minimize the inevitable financial expenses. First of all, it is worth sketching a project, carrying out the necessary balancing and power calculations. These actions will not only guarantee the successful construction of the wind farm, but also ensure that all purchased equipment is kept intact..
It is recommended to start with the construction of a micro-windmill with a capacity of several tens of watts. In the future, the experience gained will help create a more powerful structure. When creating a home wind generator, you should not focus on obtaining high-quality electricity (220 V, 50 Hz), since this option will require significant financial investments. It is wiser to limit the use of the initially obtained electricity, which can be successfully used without conversion for other purposes, for example, to support heating and hot water supply systems built on electric heaters (TEN) – such devices do not require a stable voltage and frequency. This makes it possible to create a simple circuit that works directly from the generator..
Most likely, no one will argue that heating and hot water supply in a house is inferior in importance to household appliances and lighting devices, for which power is often sought to install home wind turbines. The device of a wind turbine specifically for the purpose of providing the house with heat and hot water is the minimum cost and simplicity of design.
Generalized project of a home wind turbine
Structurally, the home project is largely the same as an industrial installation. True, household solutions are often based on vertical-axial wind turbines and are equipped with low-voltage DC generators. The composition of the modules of a household wind turbine, provided that high-quality electricity is obtained (220 V, 50 Hz):
- wind turbine;
- wind orientation device;
- DC generator (12V, 24V);
- battery charging module;
- rechargeable batteries (lithium-ion, lithium-polymer, lead-acid);
- converter of DC voltage 12 V (24 V) to AC voltage 220 V.
Wind generator PIC 8-6 / 2.5
How it works? Just. The wind turns the wind turbine. The torque is transmitted through a multiplier to the DC generator shaft. The energy received at the output of the generator is accumulated in the batteries through the charging module. From the terminals of the storage batteries, a constant voltage of 12 V (24 V, 48 V) is supplied to the converter, where it is transformed into a voltage suitable for powering household electrical networks.
About generators for home “wind turbines”
Most of the household structures of wind turbines, as a rule, are designed using low-speed DC motors. This is the simplest generator option that does not require upgrades. Optimally – electric motors with permanent magnets, designed for a supply voltage of the order of 60-100 volts. There is a practice of using car generators, but for such a case, the introduction of a multiplier is required, since autogenerators provide the required voltage only at high (1800-2500) rpm. One of the possible options is the reconstruction of an asynchronous AC motor, but it is also quite complex, requiring accurate calculations, turning work, and installing neodymium magnets in the rotor area. There is an option for a three-phase asynchronous motor with the connection of capacitors of the same capacity between the phases. Finally, there is the possibility of making a generator from scratch with your own hands. There are a lot of instructions on this matter..
Vertical-axis homemade “windmill”
A fairly efficient and most importantly inexpensive wind generator can be built on the basis of the Savonius rotor. Here, a micro-power plant is considered as an example, the power of which does not exceed 20 watts. However, this device is quite sufficient, for example, to provide electrical energy to some household appliances operating from a voltage of 12 volts..
Set of parts:
- Aluminum sheet 1.5-2 mm thick.
- Plastic pipe: diameter 125 mm, length 3000 mm.
- Aluminum tube: diameter 32 mm, length 500 mm.
- DC motor (potential generator), 30-60V, 360-450 rpm, for example, electric motor PIK8-6 / 2.5.
- Voltage controller .
Making the Savonius rotor
Three “pancakes” with a diameter of 285 mm are cut from the aluminum sheet. In the center of each, holes are drilled for a 32 mm aluminum pipe. It turns out something like CDs. Two pieces of 150 mm long are cut from the plastic pipe and cut in half lengthwise. The result is four semicircular blades 125×150 mm. All three aluminum “compact discs” are put on a 32 mm pipe and fixed at a distance of 320, 170, 20 mm from the top point strictly horizontally, forming two tiers. Blades are inserted between the discs, two pieces per tier and fixed strictly against one another, forming a sinusoid. In this case, the blades of the upper tier are displaced relative to the blades of the lower tier by an angle of 90 degrees. The result is a four-bladed Savonius rotor. For fastening the elements, you can use rivets, screws, corners or apply other methods.
Motor connection and mast mounting
The shaft of DC motors with the above parameters usually has a diameter of no more than 10–12 mm. In order to connect the motor shaft to the wind turbine tube, a brass bushing with the required inner diameter is pressed into the lower part of the tube. A hole is drilled through the wall of the pipe and the sleeve, and a thread is cut to screw in the locking screw. Next, the wind turbine pipe is put on the generator shaft, after which the connection is rigidly fixed with a locking screw.
The rest of the plastic pipe (2800 mm) is the mast of the wind turbine. The generator set with the Savonius wheel is mounted at the top of the mast – it is simply inserted into the pipe until it stops. As a stop, a metal disc cover is used, fixed on the front end of the motor, having a diameter slightly larger than the diameter of the mast. Holes are drilled on the periphery of the cover for fastening the guy wires. Since the diameter of the motor housing is less than the inner diameter of the pipe, spacers or stops are used to align the generator in the center. The cable from the generator is passed inside the pipe and exited through a window at the bottom. During installation, it is necessary to take into account the design of the generator protection against moisture, using sealing gaskets. Again, in order to protect from precipitation, an umbrella-cap can be installed above the connection of the wind turbine pipe with the generator shaft..
Installation of the entire structure is carried out in an open, well-ventilated area. A hole 0.5 meters deep is dug under the mast, the lower part of the pipe is lowered into the hole, the structure is leveled with guy wires, after which the hole is filled with concrete.
Voltage controller (simple charger)
A manufactured wind generator is usually not capable of delivering 12 volts due to its low speed. The maximum rotational speed of the wind turbine at a wind speed of 6–8 m / s. reaches a value of 200-250 rpm. At the output, it is possible to obtain a voltage of the order of 5-7 volts. Charging the battery requires a voltage of 13.5-15 volts. The way out is to use a simple pulse voltage converter assembled, for example, on the basis of the LM2577ADJ voltage regulator. By applying 5 volts DC to the input of the converter, 12-15 volts are obtained at the output, which is quite enough to charge a car battery.
Ready voltage converter for LM2577
This micro-wind generator can certainly be improved. Increase turbine power, change mast material and height, add DC-to-AC converter, etc..
Horizontal-axial windy electrical installation
Set of parts:
- Plastic pipe 150 mm in diameter, aluminum sheet 1.5-2.5 mm thick, wooden block 80×40 1 m long, plumbing: flange – 3, corner – 2, tee – 1.
- DC motor (generator) 30-60 V, 300-470 rpm.
- Wheel-pulley for an engine with a diameter of 130-150 mm (aluminum, brass, textolite, etc.).
- Steel pipes with a diameter of 25 mm and 32 mm and a length of 35 mm and 3000 mm, respectively.
- Battery charging module.
- Voltage converter 12 V – 120 V (220 V).
Manufacturing of a horizontal-axis “wind turbine”
A plastic pipe is needed to make wind turbine blades. A piece of such a pipe, 600 mm long, is cut lengthwise into four identical segments. For a windmill, three blades are required, which are made from the obtained segments by cutting a part of the material diagonally along the entire length, but not exactly from corner to corner, but from the lower corner to the upper corner, with a slight offset from the latter. The processing of the lower part of the segments is reduced to the formation of a fastening petal on each of the three segments. To do this, a square with a size of about 50×50 mm is cut along one edge, and the rest serves as a fastening petal.
The blades of the wind turbine are fixed on the wheel-pulley using bolted connections. The pulley is mounted directly on the shaft of the DC motor – generator. A simple wooden block with a section of 80×40 mm and a length of 1 m is used as the chassis of the wind turbine.The generator is installed at one end of the wooden block. At the other end of the bar, a “tail” is mounted, made of a sheet of aluminum. At the bottom of the bar, a 25 mm metal pipe is attached, designed to play the role of a rotary shaft. A three-meter metal pipe 32 mm is used as a mast. The top of the mast is the slewing bushing where the wind turbine tube is inserted. The mast support is made from a sheet of thick plywood. On this support, in the form of a disc with a diameter of 600 mm, a structure is assembled from plumbing parts, thanks to which the mast can be easily raised or lowered, or mounted – dismantled. Stretch braces are used to secure the mast.
All electronics of the wind turbine are mounted in a separate module, the interface of which provides for the connection of batteries and consumer load. The module includes a battery charge controller and a voltage converter. Such devices can be assembled on their own with appropriate experience, or purchased on the market. Many different solutions are available on the market to obtain the desired output voltages and currents..
Combined wind turbines
Combined wind turbines are a serious option for a home energy module. Actually, the combination involves combining a wind generator, solar battery, diesel or gasoline power plant in a single system. You can combine in every way, based on your capabilities and needs. Naturally, when there is a three-in-one option, this is the most effective and reliable solution..
Also, under the combination of wind turbines, it is planned to create wind power plants, which include two different modifications at once. For example, when the Savonius rotor and the traditional three-blade machine work in one bundle. The first turbine operates at low wind flow speeds, and the second only at rated ones. Thus, the efficiency of the installation is preserved, unjustified energy losses are excluded, and in the case of asynchronous generators, reactive currents are compensated.
Combined systems are technically complex and costly options for home practice.
Calculating the power of a home wind farm
To calculate the power of a horizontal-axis wind generator, you can use the standard formula:
- N = p S V3 / 2
- N – installation power, W
- p – air density (1.2 kg / m3)
- S – blown area, m2
- V – wind speed, m / s
For example, the power of an installation with a maximum blade span of 1 meter, with a wind speed of 7 m / s, will be:
- N = 1.2 1 343/2 = 205.8 W
An approximate calculation of the power of the wind turbine created on the basis of the Savonius rotor can be calculated using the formula:
- N = p R H V3
- N – installation power, W
- R – impeller radius, m
- V – wind speed, m / s
For example, for the design of a wind power plant with a Savonius rotor mentioned in the text, the power value at a wind speed of 7 m / s. will be:
- N = 1.2 0.142 0.3 343 = 17.5 W