考虑LVRT特性的规模化光伏并网系统频率响应建模方法OA

Photovoltaic(PV)units equipped with low voltage ride-through(LVRT)control adopt a reactive power priority principle during significant voltage drops,resulting in variations in active power output and subsequent participation in system frequency response.To address this,a modeling method for system frequency response is proposed,taking into account the LVRT characteristics of large-scale PV.First,based on the traditional frequency response model,the impact of large-scale integration of renewable energy sources such as PV on system inertia and primary frequency regulation is analyzed.This analysis characterizes the active power-frequency response pathway triggered by control switching behavior at PV stations during significant voltage drops.Subsequently,considering the numerous and diverse characteristics of units within a PV station,three typical LVRT active power characteristics are classified,and their dividing boundaries are established.The equivalent unit parameters are rapidly obtained by using a capacity-weighted approach.A two-stage slope method is employed to approximate the nonlinear active power characteristics of clusters,thereby establishing an equivalent active time-domain expression for the entire LVRT process of PV power stations.Furthermore,the active power variation due to LVRT at PV power stations is introduced as a disturbance excitation into the traditional frequency response model.Based on the temporal characteristics of the active power variation due to LVRT,it is segmented and represented as step changes,slopes,and other forms to obtain the analytical solution of frequency response.The impact of the LVRT characteristics on indicators such as the maximum rate of frequency change,the maximum frequency deviation,and the quasi-steady-state frequency deviation is analyzed.Finally,the accuracy and effectiveness of the proposed modeling method are validated in a 5-bus test system incorporating PV power stations.