Patent ID: 8836154
Filing Date: 2014-09-16
Classification: F03D,F05B,Y02E

Abstract:
1. A control method for controlling a variable speed wind turbine to improve electrical energy production of said variable speed wind turbine, said variable speed wind turbine having a standard regulation based on tracking an electrical power versus generator speed curve ( 31 ), wherein the electrical power versus generator speed curve has a nominal zone ( 39 ) where electrical power is kept constant at a nominal value, a first sub-nominal zone ( 33 where generator speed is kept constant at a coupling value related to mechanical coupling of a drive train of the wind turbine, a second sub-nominal zone ( 35 ) where both the generator speed and the electrical power are allowed to increase or decrease with wind speed, and a third sub-nominal zone ( 37 ) between the second sub-nominal zone ( 35 ) and the nominal zone ( 39 ), wherein the third sub-nominal zone ( 37 ) comprises a first vertical segment ( 41 ) at a generator speed (n r2 ) higher than a generator nominal speed (n r1 ) and a second vertical segment ( 43 ) at the generator nominal speed (n r1 ) connecting with the nominal zone ( 39 ), said first vertical segment and said second vertical segment being connected by an upper horizontal path (C-D) at a first point (C) and a second point (D) and a lower horizontal path (E-F) at a third point (E) and a fourth point (F), wherein each of said first vertical segment and said second vertical segment to be followed in function of the wind speed changes for optimizing the electrical energy production, said control method comprising: implementing a control strategy to follow said generator speed curve ( if the wind speed increases, an operational point of the wind turbine in said second sub-nominal zone ( if the wind speed continues increasing, the operational point in said third sub-nominal zone ( once the operational point gets to said power predetermined value (P if the wind speed continues increasing when the operational point is at said first point (C), the operational point in said third sub-nominal zone ( if the operational point is at said third point (E) and the wind speed decreases, the electrical power is going to be below the power predetermined value (P if the wind speed increases when the operational point is at said fourth point (F), the operational point is moved up along said first vertical segment (