Wind energy density grade telescopic mast wind resistance and wind power generation

Wind energy density, also known as wind power density, is wind energy that flows vertically through a unit area per unit time, in watts per square meter. It is the most convenient and valuable quantity to describe the potential of wind energy in a place.

 

Wind energy density: the kinetic energy generated by air flowing through a unit area at a speed of V within 1 second is called wind energy density.

 

Because the randomness of wind speed is very large, it is impossible to evaluate the wind energy potential of a certain area with a certain instantaneous wind speed, therefore, we substitute the average wind speed into the above formula to obtain the average wind energy density W = 1/T% 0.5% v3dt

W-the average wind energy density within the period of time 0-T

Ρ -- air density (the variation of ρ can be ignored)

V -- corresponding to the wind speed at T time

W=ρ/2T∫V3dt=ρ/2N∑Vi3

In the actual utilization of wind energy, for those wind speeds that cannot be started or operated by wind energy conversion devices such as wind generators, for example, the wind speed of 0~3 meters cannot start the fan, exceeding the running wind speed of the fan will cause damage to the fan, so this part of wind speed cannot be used. After removing these unavailable wind speeds, the wind energy density obtained from the average wind speed is called effective wind energy density.

According to the above definition of effective wind energy density, the calculation formula is obtained:

W=∫0.5ρV3P(v)dv

V1 -- start wind speed

V2 -- shutdown wind speed

P(v)-conditional probability distribution density function within the range of effective wind speed

Annual available time of wind energy:

The annual available time of wind energy refers to the time within the effective wind speed range in a year, which can be obtained by the following formula:

t=N{exp[―(V1/c)k]―exp[―(V2/c)k]}

In the formula, N is the annual hours, V1 is the start wind speed, V2 is the stop wind speed, and C and K are the two parameters of Weibull distribution.

Wind energy density, which contains the influence of wind speed, wind speed frequency distribution and air density, is a comprehensive index to measure wind energy resources of wind farms.

Note: 1. The reference value of annual average wind speed at different heights is calculated according to the wind shear index of 1/7. 2. The reference value of annual average wind speed corresponding to the upper limit value of wind power density is calculated according to the standard atmospheric pressure at sea level and conforms to the frequency distribution of the wind speed.