Control Of Photovoltaic Grid Connected Power Generation System Based On Linear Active Disturbance Rejection Control

With the continuous development of new energy technology,solar energy,as an efficient and clean new energy,has received much attention.Photovoltaic grid-connected power generation system is the key to converting solar energy into electrical energy,so it has also become a hot topic of current research.In the design and optimization of photovoltaic power generation systems,it is necessary to comprehensively consider factors such as photovoltaic cells,Maximum Power Point Tracking(MPPT)technology,and photovoltaic inverters.Maximum power point tracking technology and inverter control strategies are key to ensuring the efficient,safe,and stable operation of the entire photovoltaic grid-connected system.Appropriate control strategies are used to improve the efficiency and reliability of photovoltaic power generation systems.Therefore,this paper takes the photovoltaic grid-connected power generation system as the research object and adopts Linear Active Disturbance Rejection Control(LADRC)technology to improve the maximum power point tracking technology and inverter control strategy in the system,so that the system can still operate efficiently and stably in the face of various external disturbances.The main work of this article is as follows:Firstly,the mathematical modeling part of the photovoltaic grid-connected power generation system consists of photovoltaic cells,photovoltaic power generation system MPPT part,and photovoltaic grid-connected inverter.This article conducts mathematical modeling of each part of the photovoltaic grid-connected power generation system based on the working principle and practical engineering requirements,providing a good foundation for the research of control strategies of the photovoltaic grid-connected power generation system.Secondly,the maximum power point tracking technology of photovoltaic arrays is the key to ensure the maximization of its output efficiency.However,in practical engineering,MPPT technology is often affected by the interference caused by dust shielding,weather changes and other external conditions.Aiming at the MPPT problem of photovoltaic array in photovoltaic power generation system,an MPPT method combining particle swarm optimization(PSO)and adaptive-linear active disturbance rejection control(A-LADRC)algorithm was proposed and designed.This method overcomes the local shadow problem which can not be solved by the traditional MPPT method,and improves the anti-interference ability of the controller when external conditions change.In this method,the PSO tracks the maximum power point(MPP)on the P-V output characteristic curve of the photovoltaic array,and outputs the operating voltage when the output power of the photovoltaic array is maximized as a reference value.Then,the A-LADRC controller tracks the reference voltage and adjusts it through the Boost circuit to complete the MPPT process.The A-LADRC controller enhances the anti-interference ability against various external disturbances during the MPPT process,and accelerates the response speed of the system.The simulation results show that compared with other control algorithms such as the perturbation observation method(P&O)and traditional PSO algorithm,this method has good tracking performance and good anti-interference ability under the external interference caused by the change of external conditions.Thirdly,the DC bus voltage is regulated by the inverter control strategy,and its output stability will be affected by various external disturbances.The stability of the DC bus voltage also determines the power quality of the AC power on the grid side.However,as the traditional control strategy for photovoltaic grid-connected inverters,the voltage and current dual closed-loop control strategy has some shortcomings such as poor robustness and long regulation time.In response to the above issues,this paper proposes an application of adaptive linear active disturbance rejection control to outer loop control to achieve the purpose of anti-interference.The control strategy adopts the linear extended state observer(LESO)to evaluate external disturbances caused by changes in external conditions and internal disturbances caused by parameter uncertainties.The PD controller compensates for interference and adds adaptive control to simplify parameter adjustment.Finally,the stability analysis is carried out by using Lyapunov theory.Compared with traditional linear active disturbance rejection control,the superiority of this control strategy is verified.The experimental results show that the system has good control performance and anti-interference ability under the interference of illumination intensity mutation and voltage drop.Fourthly,the composite control scheme is designed by combining sliding mode control(SMC)with LADRC,which combines the respective advantages of SMC and LADRC to enhance the control performance of the controller.The feasibility and superiority of sliding mode control-linear active disturbance rejection control(SMC-LADRC)in DC bus voltage control of photovoltaic grid connected inverters are verified.In SMC-LADRC controller,the introduction of SMC solves the problem of control accuracy degradation caused by bandwidth constraints,and improves the robustness of the overall controller.In the LADRC controller,the LESO compensates for internal disturbances existing in the system and external disturbances caused by changes in external conditions.The main function of the PD controller is to compensate for the estimation of total disturbances.In addition,an adaptive control is added to the parameter adjustment process of a PD controller.This method not only simplifies the parameter adjustment process based on linearizing the active disturbance rejection controller,but also enhances the control performance of the controller when external disturbances occur.Finally,the practicability and superiority of SMC-LADRC controller are verified through simulation experiments.