Large scale wind power integrated into power system makes the static voltage stability margin(SVSM)computation need to consider the impact of wind farm output fluctuations. The interval number is used to describe the random fluctuation characteristics of wind farm output

the method of calculating the interval value of SVSM of power system with wind farm integration is proposed based on continual power flow method and affine-interval algorithm

Firstly

the wind power output fluctuation interval is segmented according to the different bifurcation types of voltage stability limit points. Then the continual power flow method is used to calculate SVSM corresponding to each interval central value

and then the sensitivity of SVSM to wind farm output is calculated according to the corresponding bifurcation type. Finally

the results of interval shrinkage are obtained by the optimization of noise element range based on linear programming models

and the interval of SVSM is obtained. Correlation angle is used to express the correlation of different wind farm output intervals. According to the types of bifurcation are same or not

different methods are used to calculate the interval of SVSM. IEEE 39-bus system and a provincial 964 node power grid are taken as examples

and compared with Monte Carlo simulation method

the results show that the interval of SVSM obtained by the proposed method has higher accuracy and the computation burden is reduced obviously.