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Forum Index : Windmills : I would welcome comments on this formula
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Bolty Regular Member  Joined: 03/04/2008 Location: AustraliaPosts: 81 |
Any comments would be welcome on a formula that I have come up with! If approximately valid, I would use it to estimate the power that would be generated by a wind turbine based on the recorded wind velocities. This would allow a spreadsheet to estimate the value of power generated based on observed wind recordings. The purpose of this would be to calculate the viability of a wind site, based on records, before a turbine was erected! The formula is: P = M X V X V X V (or MVcubed)..I do not know how to type a cubed symbol here where P = Power generation in watts M = Power rating of wind generator at 10 metres per second in Kilowatts V = Velocity of wind in metres per second I realize that this formula would only be an approximation, due to factors such as efficiency, wind friction, design of blades, resistance of windings etc. For my purposes, it would only need to be within 20% of the practical value. Can anybody please confirm whether or not this approximation formula works in their real time situation? Alternatively, can anyone please confirm or deny the validity of this formula from a logical or theoretical perspective? Please remeber that I do not expect this estimatiom to be 100% accurate, but to act as an indicator of power that could be expected to be generated from a turbine before it is built! Thanks for any ideas and opinions on this! Bolty |
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| Dinges Senior Member  Joined: 04/01/2008 Location: AlbaniaPosts: 510 |
You may want to check out this link... http://www.awea.org/faq/windpower.html |
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| Bolty Regular Member Joined: 03/04/2008 Location: AustraliaPosts: 81 |
Thanks very much for that link! It contains a lot of useful information that I have not previously seen. Makes my question superfluous! Thanks again! |
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GWatPE Senior Member Joined: 01/09/2006 Location: AustraliaPosts: 2127 |
Hi bolty, I would rate my site as OK for wind capture, based on the latest kWhr data for my mill. The wind data at my site gave a yearly average windspeed of 6knots, approx 3m/s. The max windspeeds, over 20m/s occurred rarely. The 10m/s windspeeds occurred on about 20% of the days, for less than 20% of the time on those days. The average is so much less than the recorded maximums that a weatherstation logs. Take care using this data. I presume you are back? Gordon. become more energy aware |
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| Bolty Regular Member Joined: 03/04/2008 Location: AustraliaPosts: 81 |
Thanks Gordon. I kind of recall that you mentioned these figures once before when we where first talking. Problem was that I was so overloaded with info that I had forgotten about it! I now recall your advice re the lower than expected values. More particularly I remember that the instantaneous values vary so much that a monitoring of wind data cannot catch accurately. Thanks for the reminder. Yes I am back but only until Tuesday. We are going to WA for 16 days. Such is the life of a retiree! Actually I can't wait to get back so that I can do some serious work in getting the turbine up. Bloody holidays interrupting serious works! At least in my few days home, I have had time to be able to catch up with missed times from this forum! Catch you soon! |
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| Bolty Regular Member Joined: 03/04/2008 Location: AustraliaPosts: 81 |
By the way Gordon, my inverter has been installed whilst I was away, and it has generated only 69 KWh...not sure over how many days, but I would estimate around 40 days. So 1.7 KWh per day is not much, but I guess that it has been very wintery and overcast. On energy production, I did notice that one day this week there was a completely clear sky at about 2.30 pm. Despite no clouds, the power production was only around 290 watts. I assume that this is to be expected at this time of the year, due to the low elevation of the sun. Also the afternoon sun means anothere reduction due to the angle to the west. In theory, is it the case that a vertical angle of 45 degress of the cells to the sun, means a reduction of power to 70.7%. Is it also the case that in theory another angle of 45 degrees (to the west) reduces the 70% to 49% If these theoretical assumptions are correct, is the theoreticl value matched by observations, or do other factors come into play....eg the thickness of the covering to the cells etc. Because my cells are angled at 17.5 degrees from the horizontal, would there be significant practical benefit in raising the angle. |
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