tailieunhanh - Wind Farm Impact in Power System and Alternatives to Improve the Integration Part 6

Tham khảo tài liệu 'wind farm impact in power system and alternatives to improve the integration part 6', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | 114 Wind Farm - Impact in Power System and Alternatives to Improve the Integration Where p density-dependent temperature P power generated by wind turbine Cp drag coefficient of power specific to the wind farm V wind speed D diameter of the blades This expression is quite similar for different manufacturers and turbine types. The power is null if the wind speed is less than a starting speed cut - in speed Vd 2 to 4 m s this power is also proportional to the wind speed rise between cut - in speed and the rated speed about Vnom 12 to 16 m s . At the rate speed the power is near its nominal value. Power is constant between the rated speed and cut - out speed Vmax 25 to 30 m s . Beyond the cut-off speed the turbine is stopped for safety reasons. By observing Figure 5 we see that the winds are more frequently at low and average speed than at strong velocity. Otherwise the 2 shows that the average wind power supplied by the turbine varies strongly with the cube of the average wind speed. Thus a doubling of wind speed corresponds to an increase in its capacity energy 2A3 8 times. Consequently the variability of the wind and the process of energy conversion makes the wind generation an intermittent nature. The electric grid is considered as an intermittent source The electric grid is a complex multi-actor system consisting of many uncertain factors like technical human and natural factors. The uncertainty is present at several levels. Stochastic variation of demands usually considered as the prediction error has important effects on anticipating and on managing the real-time system. It is due to some related climates and consumer behaviours. Several types of uncertainty exist in electricity generation where the generating units cannot reach their production plans or where the production unit cannot start as expected or is stopped suddenly by natural or technical causes. Operation limits of the transportation and distribution systems have to be taken into account. The risk