恒速风电机组极限切除时间的确定

为分析电网故障时恒速风电机组的暂态稳定性及其对电网的影响,首先,以等面积法则为理论依据.利用感应发电机的转矩-滑差曲线和机械输入转矩曲线,确定了感应发电机的极限切除时间;其次,考虑电网故障时刚性度较低的风电机组轴(采用双质块模型)的松弛所释放出的能量使感应发电机的加速而导致发电机的加速面积增大且大于其减速面积,因此恒速风电机组中感应发电机的极限切除时间小于单纯的感应发电机极限切除时间;最后,根据恒速风电机组所使用感应发电机的极限切除时间确定恒速风电机组极限切除时间.通过仿真分析得出恒速风电机组轴刚性度对机组极限切除时间的影响,随机组轴刚性度增大机组的极限切除时间增大,但是当轴的刚度系数增加到一定程度时,风电机组的轴就可看作单质块模型,机组的极限切除时间就不再增加.

Estimation of critical clearing time of constant speed wind turbines

The transient stability of wind turbine during power fault and effect on power network are studied.Based on the equal area rule,the CCT(Critical Clearing Time) of induction generator is determined with its torque -slip curve and mechanical torque curve.Since the released energy during the relaxation process of wind turbine shaft(two -mass model) increases its speed,making its acceleration area increased and bigger than its deceleration area,the induction generator CCT of constant speed wind turbine is shorter than that of normal one,by which the CCT of wind turbine is determined.Simulative analysis points out that,the bigger the wind turbine shaft stiffness is,the larger the CCT of constant speed wind turbine is.When the shaft stiffness of wind turbine is big enough,the CCT of constant speed wind turbine will not increase along with the stiffness increase,it means that,the wind turbine shaft is of lump-mass model.