|Forum Home > Welcome to Australian Wind and Solar > How do wind turbines work ?|
Types of Wind Turbines
Modern wind turbines fall into two basic groups: the horizontal-axis variety (AWS H series) and the vertical-axis design (AWS V Series), Horizontal-axis wind turbines typically have three blades. These three-bladed wind turbines are operated "upwind," with the blades facing into the wind. The blades of a horizontal turbine are design to optimise lift and drag to spin the rotor. The wind force is typically even across all three blades at all times. Vertical-axis wind turbines typically have four blades. These four blades operate the turbine in any wind direction and are therefore more suitable for more turbulent areas i.e. city or densely populated areas. Four blades are used on a vertical turbine as usually one blade at any one point will be obscured from wind "dead spot". It’s important to note that an each type of turbine will outperform the other depending on where it is installed.
Size of Wind Turbine
Wind Turbines can range from as little as 100 Watts typically used for charging a very small battery bank, boats, sheds; to 1 or 2 Megawatts turbines seen on wind turbines farms used to power entire cities. Common residential / commercial turbines are 1Kw to 5Kw. Sizes a turbine is a specialist task, bigger is not always better or economical. Also two of 5Kw turbines can outperform one of 10Kw turbine in areas where wind speed is moderate, although in high winds a 10Kw turbine will outperform two 5Kw turbines. Check your average wind speed and compare it to the manufacturers output chart (All AWS turbines output charts are available to view online) also check the maximum wind speeds and how much time the wind is at that speed. A good resource is the BOM rose chart available at http://www.bom.gov.au/climate/averages/wind/wind_rose.shtml
Keeping it simple a Wind Turbine consists of the blades variants described above and a rotor. There are also bearings, shaft, a permanent magnet generator and a housing. Along with a pole, cable, rectifier and finally batteries or a grid connected inverter which we will explain a little later. Quality is paramount. Remember your turbine contains moving parts and the internal bearings, permanents magnet generator and what will likely wear first. Blades also need consideration, commonly fibre glass blades will be used and then the up speced Carbon fibre (The new AWS C series have Carbon fibre blades). Professional installation and good balancing will of course ensure your turbine performs well and does not unnecessarily wear due to poor installation methods. Maintenance is very important and not necessarily expensive, a major cause of turbine failure is incorrect installation by non-qualified persons and little to no maintenance. Just think, how long will your car run without any maintenance?
Turbine Tower / Mast
Height is going to make all the difference or no difference at all. Let me explain; a site consisting of a house, sheds, trees and a wind turbine proposed at a location approximately 20 meters from the house. The house is located west of the turbine and our rose chart and on site readings confirm predominate wind prevailing west. The turbulent zone we need to clear varies from 20 metres (height of house) up to 40 meters and of course back to 0 metres. The height of the tower can be 10 meters without any adverse performance decline but could need to be up to 40 metres in the precise "wrong" location. In this case relocating the turbine only a few meters could make all the difference. Location is extremely important.
Grid Off / Grid On
A grid on Wind turbine is an excellent way to reduce or eliminate your electricity bill. The use of a wind turbine alone or with the additional of a solar system are both practical, affordable and achievable. As a wind turbine typically produces its power over a longer period of the day or night most of this power is likely to be consumed and therefore rather than feeding power into the grid at little to no rebate you actually benefit from the saving. 1Kw of fed in power is equal to 5 Kw of used power. Therefore a 1Kw wind turbine could save you just as much as a 5 Kw solar system. It is important to understand that the size of your wind turbine and output needs to match an AUSTRALIAN APPROVED AS4777 grid on wind inverters. There are only 2 brands of approved grid connected wind inverters allowed to be connected to the Australian power grid. See our web store http://www.australianwindandsolar.com/apps/webstore/ . Connected to the Australian Grid (in any state) requires the following that are mandatory.
1. The use of a CEC wind endorsed person the endorsement MUST be carries for both design and installation CEC.
2. Must be a qualified electrical contractor and qualified electrician in your relevant state. These are often thought of as the same item, they are not. Simply holding an Electrical license does NOT allow the person to carry out electrical works on your premises. They must also hold a "Contractors" license and hold the correct level of insurance.
3. The grid connected inverter must be an AS4777 approved inverter, approved by the local power distributor and ALL necessary paperwork / online paperwork completed. (Victoria also needs an independent inspection).
4. Only when the above steps and forms are completed will you be entitled to the current level of government rebate for your system.
An off grid installation still requires the appropriate accreditation from CEC and will still require a licensed electrician. It is often a misconception that no qualification or a different qualification is required, actually more qualifications / certifications are required for an off grid installation than an on grid. The first question your insurance company will ask for in the event of loss or damage is "Where is your certification". Also you are entitle to government grants just like an on grid system if you engage the appropriately qualified and certified company. Of course why would you put your family at risk by not doing so? An off grid Turbine works in the same manner as an on grid but the difference is the turbine power is fed via a rectifier and (all in one or a separate unit) a charge control system. Don’t be tempted by the cheap nasty items flooded on the market. The battery management system will make ALL the difference between ensuring your costly battery system last 2 years or 10. We will talk about this in another topic or feel free to ask questions. A quality off grid inverter will also ensure you are not constantly left in the dark every time a pump of washing machine is turned on. We use SMA and Selectronic controllers. (German and Australian).
I hope this brief summary provides a basic understanding of what is happening from your Wind Turbine to your grid or battery system. Please feel free to open up the discussion and ask as many questions as you can think of.