3.6.2.4 Pitch Control Vs. Stall Control
3.6.2.4 Pitch Control vs. Stall Control
The rotating actions on the turbine are used in both the pitch and active stall controls. However, the pitch control turns the turbine blade out of the wind, leading to reduction in lift force, whereas the active-stall control turns the turbine blades into the wind, causing turbulences that reduced the lift force [23]. The passive stall may not be able to keep the captured power PM at a constant value, as shown in Fig. 3-20 and it may exceed the rated power at some wind speeds [35]. The passive stall control was mainly used in early fixed-speed turbines. This control technique was further improved into the active stall technology [35]. Using the active stall control, it is possible to maintain the rated …show more content…
They are designed to achieve maximum efficiency at a particular speed. The fixed speed wind turbine features simple structure, low cost and reliable operation. However, it has a lower energy conversion efficiency compared to a variable speed wind turbine since it can extract maximum power only at one given wind speed [3].
The fixed speed WECS starts to produce power when the wind speed is higher than the cut-in speed (3-4 m/s). At a speed higher than the rated wind speed (13 to 15 m/s), the power captured by the turbine is limited either by active/passive stall or pitch control of the rotor blades [23]. At a speed higher than the cut-out speed (around 25 m/s), the turbine is stopped by either full stall or full pitch of the blades to protect the turbine and generator from possible damage [23]. The rotating speed of large fixed speed turbines is normally in the range of 6 to 15 rpm, whereas the induction generator operates at much higher rpm (750 rom to 1800 rpm). The generator operating speed is determined by the number of poles and grid frequency
The rotating actions on the turbine are used in both the pitch and active stall controls. However, the pitch control turns the turbine blade out of the wind, leading to reduction in lift force, whereas the active-stall control turns the turbine blades into the wind, causing turbulences that reduced the lift force [23]. The passive stall may not be able to keep the captured power PM at a constant value, as shown in Fig. 3-20 and it may exceed the rated power at some wind speeds [35]. The passive stall control was mainly used in early fixed-speed turbines. This control technique was further improved into the active stall technology [35]. Using the active stall control, it is possible to maintain the rated …show more content…
They are designed to achieve maximum efficiency at a particular speed. The fixed speed wind turbine features simple structure, low cost and reliable operation. However, it has a lower energy conversion efficiency compared to a variable speed wind turbine since it can extract maximum power only at one given wind speed [3].
The fixed speed WECS starts to produce power when the wind speed is higher than the cut-in speed (3-4 m/s). At a speed higher than the rated wind speed (13 to 15 m/s), the power captured by the turbine is limited either by active/passive stall or pitch control of the rotor blades [23]. At a speed higher than the cut-out speed (around 25 m/s), the turbine is stopped by either full stall or full pitch of the blades to protect the turbine and generator from possible damage [23]. The rotating speed of large fixed speed turbines is normally in the range of 6 to 15 rpm, whereas the induction generator operates at much higher rpm (750 rom to 1800 rpm). The generator operating speed is determined by the number of poles and grid frequency