Influence of maximum turbulent intensity on unit s

2022-07-24
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Influence of turbulence intensity on unit type selection

turbulence is a chaotic and irregular flow state, and its flow parameters change randomly with time and space. Therefore, it is essentially a three-dimensional unsteady flow, and numerous vortices of different shapes and sizes are distributed in the flow space. It can be said that turbulence is a random three-dimensional unsteady swirling flow

in order to make full use of the wind energy resources of a specific wind farm and ensure the safe and reliable operation of wind turbines, IEC has carried out safety classification for wind turbines

the latest version of IEC is the third edition published in August, 2005, of which the first edition was published in 1994 and the second edition was published in 1999. Most of the popular wind turbines in the market are designed according to the second or third edition of IEC

Table 1: classification of wind turbine in IEC Second Edition

iec second edition defines standard fan type based on characteristic turbulence intensity at 15m/s wind speed

characteristic turbulence intensity: for 10 minute steps, each step contains a turbulence intensity value. The fuel efficiency is increased by 36%. The characteristic turbulence intensity is equal to the 84th percentile of these turbulence intensity values, that is, 8% of the value will be less than this value while implementing the national and provincial inclusive policies at the end of September. If the turbulence intensity follows a normal distribution, the 84th percentile is equal to the mean plus the standard deviation

Table 2: classification of wind turbines in IEC version 3

iec version 3 defines standard fan types based on the average turbulence intensity at 15m/s wind speed

another concept proposed in the third edition is to represent the turbulence intensity: for a 10 minute step, each step contains a turbulence intensity value, which represents that the turbulence intensity is equal to the 90th percentile of these turbulence intensity values, that is, 90% of the values will be less than this value. If the turbulence intensity follows a normal distribution, the 90th percentile is equal to the mean plus 1.28 times the standard deviation

the usual method for resource analysis is to judge whether the site area exceeds the fan classification standard specified by IEC according to the turbulence intensity at the wind tower according to the needs of users. However, the fan points usually located in the downwind direction are often affected by the wake of the upwind fan, which increases the turbulence intensity of the downwind fan. Therefore, the turbulence intensity produced by the tail of the fan should be considered. Therefore, the effective turbulence intensity borne by the wind turbine in the wind farm consists of two parts: the ambient turbulence intensity and the additional turbulence intensity considering the influence of wake

treatment method when the turbulence intensity of the wind turbine exceeds the standard: adjust the fan layout around the unit and pull the fan spacing; Properly increase the height of wind turbine tower

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