Transient Stability Analysis Of Power System Containing Wind Farms

Power demand has increased steadily in recent years,and the environment problem is becoming more and more serious.There is an increasing demand for clean energy.Wind power,as a clean energy,has developed rapidly in recent years.After the wind farm connected to the power system,its uncertainty has an influence on the safe and stable operation of the power system.In this paper,we propose a wind speed forecasting method considering spatio-temporal correlation,establish a wind farm model,and then apply probabilistic method to analyze the transient stability of power system containing wind power.There is a time correlation and a spatial correlation among the wind speed of large wind farms.Considering the temporal and spatial correlation of wind speed,the RST model is established to predict the wind speed in the short term.Different from the traditional method,the RST model assumes that the wind velocity obeys the truncated normal distribution,and the spatial and temporal correlation of the wind speed is reflected in the model of the parameter of the wind velocity distribution.The distribution parameters are obtained from the historical wind speed data,and the short-term prediction of wind speed is carried out after the establish of RST model.The predicted wind speed is converted to the output power of the wind turbine.And then we connect the wind power to the power system in the load model of 40% constant power and 60% constant impedance.In the process of transient stability analysis by using probabilistic method,instead of the traditional Monte Carlo method,Blind Kriging agent model is used to obtain the relevant parameters of transient stability(the generator relative angle,the node voltage and the relative frequency of the system).Blind Kriging model is a black box agent model.Taking the predicted wind speed as the model input,and using the corresponding generator relative angle,the node voltage and the relative frequency of the system as the output,the Blind Kriging agent model is established.Applied to IEEE-39 bus system,and compared with the Kriging model and Monte Carlo method,the Blind Kriging model is much more efficient and accuracy in the transient analysis of power system transient.Compared with the results of Monte Carlo method in practical system of Yunnan power grid,it is proved that the Blind Kriging agent model is practical in solving practical problems.At the same time,two examples show that the uncertainty of wind power has some influence on the transient stability of the system.