Our wind turbines have been designed by a collaboration between ourselves and a Scottish design company experienced in making rugged turbines. Our tower has been developed by an Irish engineering business. The focus is on providing reliable, effective turbines capable of surviving winds up to 140mph. At the same time, our unique combination of a state of the art generator and inverter maximises output in low wind conditions.
We offer a grid tie 2.5kw system which is a fit-and-forget system, with fully automatic control of the turbine and grid connection. Alternatively, we can also offer an off grid solution which can use battery banks. The only maintenance required is an annual visual inspection by the owner, five-yearly inspection of blades with blade replacement after ten years and generator bearing replacement every 20 years. Many wind turbines require annual maintenance – great for installers, but the cost of doing this is usually overlooked when estimating the payback time for turbine systems.
Rugged Downwind Design
Our turbine and blades face away from the wind. This provides good directional stability and enables Turbotricity turbines to survive extreme conditions more easily than upwind machines.
Traditionally downwind turbines suffer from tower shadow and as the blade passes the shadow of the tower, it loses the wind briefly, and this can cause lost power and occasional noise. We have minimised these effects by using a 6 blade design.
The Turbotricity Wind Turbine is designed for the conditions in Ireland and the UK. The component parts of the product are all chosen with durability, efficiency and availability in mind. The following are the key component parts:
Electricity is produced when a magnet passes a coil of wire. This is the basis of all generators, but there are unique features we use to optimise efficiency.
Most generators use an iron core around which the copper coil is wound. This reduces the efficiency of the generator, and introduces a cogging effect under low load which prevents the turbine from starting under low wind speed conditions.
In our generator, the coils are wound on a resin core which eliminates cogging and improves efficiency, enabling the generator to convert up to 94% of the energy from the blades into electricity. The system is commonly referred to as “axial flux” but in our case, the coils are on a more robust drum rather than a disc, and so it is better described as “air core radial flux”
Unusually in our generator, the shaft is fixed and the body of the generator holds the magnets and rotates. This provides a more robust mounting system for the rotor hub carrying the blades.
The bearings in the generator are greased for life and should require no maintenance for 20 years in normal conditions.
Many turbine manufacturers use slip rings at the top of the tower to connect the turbine (which yaws with the wind) to the cable going down the tower (which is fixed). These slip rings require annual maintenance and also can cause electricity loss.
Downwind turbines seldom rotate clockwise or anti-clockwise more than once or twice in the same direction, and for this reason, we prefer to use a very flexible cable and directly connect the turbine to the cable. This reduces the need for annual maintenance, though the cable should be visually inspected though the inspection cover on the base of the tower once a year to ensure that the cable has not twisted.
Blades & Hub
Our blades are one-piece injection moulded in glass reinforced polyamide. This is an extremely tough material which ensures that blades cannot delaminate and break up as has happened with fibreglass blades in the past.
The blade profile is a computer aided design, using the latest aerodynamics software to optimise energy output for blade length, ensuring that the turbine has maximum strength in extreme wind conditions.
The blade root is fitted to a Multiwing™ hub which is an off-the-shelf component used in industrial fans. This allows the injection moulded blade to have a strong hub root, while minimising component cost. The hub is capable of operating with loads far higher than will be experienced on the Turbotricity wind turbine system.
The pitch of the blade is set using pitch pins. Extensive trials have shown that the optimum blade pitch for our blades is 26° and the system comes with appropriate pitch pins included.
We are using an Irish made free standing tower, engineered to withstand wind in excess of 65 m/sec (145 mph). Guyed towers, often used on budget turbines, require annual maintenance and can fail with catastrophic results. They should not be used in domestic wind systems unless appropriate maintenance and inspection can be assured and are not suitable for use in areas grazed by cattle or horses.
Many wind turbine towers are raised and lowered using a winch and gin-pole arrangement. For this to be safe, a second concrete anchor point is required. We have opted to raise and lower safely using a hydraulic ram which is powered by an electric pump, or using tractor hydraulics on remote sites. This saves on concrete foundations, and simplifies maintenance and installation.
Power Management System
Domestic wind generators produce variable quality electricity, referred to as “wild AC” because both the voltage and frequency are variable. The power management system converts this wild AC into useable electricity, and controls the generator in extreme wind conditions. There are two main components – a Controller and a Grid Tie Inverter.
This unit converts the wild AC into DC or direct current. A programmable microprocessor monitors turbine output to assess wind conditions, and in the event of either extreme wind conditions or grid failure, can apply two stage braking to initially slow, and finally stop the turbine from rotating. The controller then monitors conditions to ascertain when it is safe to start the turbine again.
The programmable microprocessor has a display which lets the owner know if the turbine is running, and if not, why not.
Grid Tie Inverter
The inverter must convert the DC power from the controller into AC electricity at a voltage and frequency that matches and is in synch with the grid. It is important for the safety of electricity line staff that the inverter cuts out during a power cut to prevent electrocuting staff who have shut off the power who are working on the lines.Our inverter conforms fully with standards required under EN50438 and additional standards required by ESB to ensure quality of the electricity supply.
Our system is matched to the Aurora 6kw grid tie inverter which has a number of features:
- It operates once the voltage exceeds 50V ensuring that in light winds, we can harness even the very small amounts of power available (many inverters only start up at voltages above 200V)
- It uses modern power conversion technologies to ensure efficiency of up to 96% meaning that the system harvests maximum usable energy.
- Most wind inverters only have three or four power points available. This is rather like a car only having three gears. Our inverter has 16 power points available for us to programme, enabling us to optimize power output over the entire working range of the turbine.
- The inverter comes with a computer interface for monitoring of performance if required, and is compliant with EN50438, the EU standard required for grid connection in Ireland. We can provide inverters for G83 in the UK, or 60Hz for USA / Carribbean and other markets.