Research On Primary Frequency Control Strategy Based On Active Control For Wind And Photovoltaic Power Generation

In recent years,generating electricity technology by new energy represented by wind and solar energy have become a hot research field.The characteristics of wind and solar energy determine the power fluctuation of wind power and photovoltaic power generation.With the increase of installed capacity and power generation,the grid-connected wind power and photovoltaic power generation have affected the safe and stable operation of the power system,and have caused cause serious phenomena of wind and solar curtailment in some countries or regions.Therefore,it is great theoretical and practical significance to change the power control methods of the grid-connected system for wind and solar power generation,and further study their primary frequency modulation ability so that they can participate in the primary frequency regulation.This paper studies the primary frequency regulation control strategies of the grid-connected wind power and photovoltaic power,and proposes active power control strategies.The main research content are as follows:The research background and significance of wind and solar power are introduced,and the reasons for their involvement in system primary frequency regulation are explained at the same time.The grid code for wind power and photovoltaics into power system are summarized,and the current research status of active power and frequency control is introduced in detail.The basic structure and control strategy of the doubly fed wind turbine and photovoltaic cells are studied.This paper simply introduces the basic composition of doubly fed wind turbine,focusing on the analysis of the overall control strategy of doubly fed induction generator;The principle of photovoltaic generation,the mathematical model and output characteristics of photovoltaic cells are introduced.The control strategy of photovoltaic grid connected inverters and maximum power point tracking control of photovoltaic cells are mainly studied.Based on the control strategy of wind turbines involved in primary frequency regulation and improves the virtual inertial control of wind turbines,and proposes an adaptive inertia control based on rotor overspeed control.According to the wind speed,unit operating status and system frequency,the control coefficients of the adaptive inertia control are changed in real time to adjust the active output to participate in system primary frequency regulation.This control strategy avoid the wind turbine releasing too much energy under low wind speed,causing the speed to be lower than the minimum and wind turbine off power system;And providing active support under high wind speed.The wind power grid connected system is built on the Matlab/Simulink simulation platform.The effects of the two reference control strategies and the proposed control strategies are compared under low wind speed,high wind speed and random wind speed to verify the effectiveness of the proposed control strategy.A primary frequency regulation control strategy for photovoltaic power plant based on variable power reserve level control are proposed,that changed the power reserve level by responding to the frequency to participate in the system primary frequency regulation.According to the fitting of output data of photovoltaic cells,the relation between the power reserve level and the derivative of the power with respect to the voltage(dP/dV)is obtained,and then control voltage by improved hill climbing method,so as to achieve active and frequency control.The model of photovoltaic cell is simplified,and the relationship between light and cell output is deduced in reverse.The model of photovoltaic grid connected power generation system is built on the Matlab/Simulink simulation platform.Firstly,proving the variable power reserve level control is effective;Respectively carrying out simulation analysis with load mutation,random load and light conditions to verify the validity of the proposed frequency modulation control,compared to photovoltaic system doesn't participate in primary frequency regulation.Finally,aiming at the coexisting presence of wind and photovoltaic power in the power grid,the wind turbine is connected to the photovoltaic grid connected power modulation system to verify the feasibility of combined wind and photovoltaic power participating in the primary frequency regulation.