Generator Torque at the Mechanical Load voltage Load current Electrical rotation speed wind turbine power at the (V) (A) power to the (r/min) rotor (Nm) wind turbine load (W) rotor (W) Maximum 0.05 5 43 0 0 540 0.2 11.3 24 0.54 13.4 475 0.27 13 20 0.68 13.8 360 0.38 14 13.7 0.9 12.4 245 0.4 10.3 7.2 0.96 7.1 180 0.35 6.5 4.4 0.8 4 70 0.2 1.5 0 0.6 0 speed: 840 Minimum speed Table 3: Measuring the parameters of the wind turbine at a wind speed of 4 m/s (14.4 Generator Torque at the Mechanical Load voltage Load current Electrical rotation speed wind turbine power at the (V) (A) power to the (r/min) rotor (Nm) wind turbine load (W) rotor (W) Maximum 0.05 8 73 0 0 1060 0.44 49 48.2 1.08 52.4 950 0.58 60 42 1.4 60 790 0.9 74 30.8 2.0 63 620 1.15 75 20 2.7 52 515 1.25 69 4.5 2.84 40 152 0.73 12 0 1.7 0 speed: 1420 Minimum speed km/h or 9.0 mph) Table 4. Measuring the parameters of the wind turbine at a wind speed of 7 m/s (25.2 km/h or 15.7 mph). Generator Torque at the Mechanical Load voltage Load current Electrical rotation speed wind turbine power at the (V) (A) power to the (r/min) rotor (Nm) wind turbine load (W) rotor (W) Maximum 0.05 10 103 0 0 1625 0.71 120 73 1.6 120 1500 0.94 145 65 2.16 140 1280 1.4 190 50 3.37 168 1050 1.9 220 33 4.3 144 970 2.2 210 25 4.348 110 517 2.6 141 0 4.348 0 speed: 2000 Minimum speed Table 5: Measuring the parameters of the wind turbine at a wind speed of 10 m/s (36 km/h or 22.4 mph). 20. Mechanical power vs. speed for 4 (bottom), 7 (middle), 10 (top) m/s 3 2,6 Torque (W) 2,5 2,2 1,9 2 1,4 1,251,15 1,5 0,71 0,58 0,44 0,4 0,38 0,35 0,27 0,2 0,2 0,5 0,94 0,9 0,73 1 0,05 0,05 0,05 0 0 500 1000 1500 2000 2500 Speed (rpm) DC current vs. DC voltage for 4 (bottom), 7 (middle), 10 (top) m/s 5 4,348 4,5 4,348 4,3 Load current (A) 4 3,37 3,5 2,84 3 2,7 2,5 1,5 1 0,6 2,16 2 2 1,7 1,6 1,4 1,08 0,96 0,9 0,8 0,680,54 0,5 0 0 0 0 0 20 40 60 Load voltage (V) 80 100 120 21. Mechanical power vs. Speed for 4 (bottom), 7 (middle), 10 (top) m/s 250 220 210 190 Mechanical power (W) 200 145 141 150 120 100 69 75 74 60 49 50 12 10,3 14 1311,3 1,5 6,5 10 8 5 0 0 500 1000 1500 2000 2500 Speed (rpm) Electrical power vs. Speed for 4 (bottom), 7 (middle), 10 (top) m/s 168 180 160 144 140 ELec trical power (W) 140 120 110 120 100 80 63 60 52 60 52,4 40 40 7,1 0 04 20 13,4 12,413,8 0 0 0 0 0 0 500 1000 1500 Speed (rpm) 2000 2500 22. Because there is energy lost in the process of mechanical power to electrical power. Such as friction loss in Gearbox Wind Speed Maximum Maximum Optimum Optimum Generator mechanical electrical speed at the torque at the efficiency (% power (W) power (W) wind turbine wind turbine rotor (r/min) rotor (N·m or lbf·in) 4 m/s 7 m/s 10 m/s 14 75 220 13.8 63 168 475 790 1280 0.27 0.9 1.4 98.57 84 76 23. When the wind speed increase, the generator efficiency decrease. Because higher speed led to higher mechanical lost. The wind speed reaches 7m/s and 10m/s, The wind turbines stall as wind speeds increase. Air and wind motor blade stripping phenomenon, efficiency also decreased 24. Maximum electrical power vs. wind speed 168 Maximum electrical power (W) 180 160 140 120 100 80 63 60 40 13,8 20 0 0 2 4 6 Wind speed (m/s) 8 10 12 Maximum mechanical power vs. wind speed Maximum mechanical power (W) 250 220 200 150 100 75 50 14 0 0 2 4 6 8 10 12 Wind speed (m/s) Ideally, bring the data into the following cubic formula for maximum mechanical power versus speed. The maximum mechanical power is proportional to the cube of the speed with the air density and the windward surface fixed. Because the efficiency of the generator is greater than 30%, the maximum electrical power is also proportional to the cube of the speed and REVIEW QUESTIONS 1. Pw=1/2ρAv3=0.5*1.225kg/m3*10m2*(4.5m/s)3=558.14W 2. When the wind speed doubles: Pw=1/2ρAv3=0.5*1.225kg/m3*10m2*(9m/s)3=4465.12W When the wind speed triples: Pw=1/2ρAv3=0.5*1.225kg/m3*10m2*(13.5m/s)3=15069.8W The power is proportional to the wind speed. 3. The rotor efficiency coefficient (Cp) is the ratio of the actual power produced by the wind turbine divided by the total wind power flowing into the turbine blades at a particular wind speed. Cp indicates the wind turbine efficiency. Pm=500W/0.47=1064W 4. The torque is inversely proportional to the rotor speed. The Mpp indicates the speed makes the wind turbine reaches the maximum power. Because the optimum speed is the speed that makes the wind turbine reaches the maximum power point. 5. Based on the Figures. As the rotor speed increased, Mpp of mechanical power also increases. Because the rotor speed is proportional to the Mpp of the mechanical power. Yes, it does. The maximum electrical power produced by the wind turbine generator vary in the same way as the MPP with rotor speed.