Research On Low Frequency Oscillation Suppression Of Power Systems With Photovoltaic-battery System

With the economic development and the depletion of traditional energy sources,environmental pollution and energy crisis have become urgent problems to be solved.With its clean and renewable characteristics,new energy has been vigorously promoted in recent years,and its installed capacity has reached a record high.New energy sources connected to the grid inevitably improves the degree of power electronics,which brings new challenges to power system stability,among them the low frequency oscillation is the important problem.Due to the lack of inertia,high penetration photovoltaic-battery system connected to the grid will bring uncertainty to the damping of the system and even to negative damping.At the same time,the damping control of photovoltaic-battery system also provides a new way to solve low frequency oscillation problem.Therefore,There is great practical and theoretical significance to study the additional damping control of photovoltaic-battery system in order to suppress the low frequency oscillation.In this paper,the principle of photovoltaic generation and energy storage system was introduced,and its grid-connected model and power control strategy were established,which laid a theoretical foundation for the additional damping control of the photovoltaic-battery system.Then,an additional damping controller of photovoltaic plants was designed based on the active disturbance rejection control(ADRC),which was robust and not controlled by the mathematical model of the object.The impact of the ADRC additional damping control on the damping coefficient of power system was derived by the complex torque coefficient analysis.Finally,considering the relationship between the damping power and the power rating of the energy storage system and the state of charge(SOC),the additional damping control strategies and structure of the photovoltaic-battery system were designed.The effectiveness of ADRC and the control strategies to suppress low frequency oscillation was verified by simulation in single-machine infinite bus system and 4 machines 2 areas system.