Calculation Of Wind Power Limit Considering Primary Frequency Regulation Constraint Under Wind Power Disturbance

With the development of wind power technology,the proportion of wind power in power system energy is growing greatly.In this case,second-level wind power fluctuation resulting from wind turbulence,plays a growing important role on primary frequency regulation,because it leads to a decrease on reserve capacity and an increase on demand relatively.If neglected,the synchronous units may fail to meet the capacity demand for the grid’s primary frequency regulation,even leading to low frequency load shedding in severe cases.Therefore,study of grid primary frequency regulation characteristics under wind power fluctuation and the changes in maximum wind power penetration that may cause is a major concern in power system planning.Wind power fluctuation,which differs from load fluctuation,is greatly fluctuating and unpredictable,and its influence on primary frequency is different too because a difference on frequency components exists.With the increase of wind power penetration,it isn’t enough to consider the system’s primary frequency capacity under load disturbances.Thus,take the analysis of the impact on primary frequency under wind power fluctuation into two steps: One is the characteristic analysis of wind power fluctuation,especially second-level wind power fluctuation.In this paper,since the high turbulence characteristics,time correlation and spatial correlation of wind speed,the minute-level wind power fluctuation based on the distribution characteristics and delay characteristics of wind speed is constructed.And then,from the perspective of frequency domain,the power spectral density function is applied to construct a second-level wind speed with the consideration of wind speed correlation,which is a correlation between the oncoming wind speed of wind turbines.And then the wind farm second-level power fluctuation is constructed with wind speed and wind turbine model.And a more accurate wind power fluctuation is provided for analysis of its impact on primary frequency regulation.The other is the analysis of primary frequency response process under active disturbances.By using the IEEE 39 bus system model in DIg SILENT to equal the simplified single machine model in Matlab,the primary frequency response process is described and so that the effect of wind power disturbances on the primary frequency regulation can be analyzed accurately.Based on the above wind power fluctuation characteristic analysis and equivalent primary frequency response model,a calculation model of maximum wind power penetration considering wind power fluctuation characteristic and load disturbance is established.Specifically,and the impact of wind power fluctuation on the dynamic frequency of the power grid is analyzed using wind speed simulation and grid equivalent models.And a primary frequency regulation index is obtained through the simulated wind power fluctuation.Then,the opportunity constraint programming was introduced because of the uncertainty of wind power,and the particle swarm optimization algorithm was used to solve the maximum wind power penetration.Finally,the effectiveness of considering the influence of wind power fluctuation on grid dynamic frequency is verified on the IEEE 39 bus system.