Research On Control Strategy Of Photovoltaic Grid Connected Inverter Based On ADRC

In recent years,economy,energy and environment(3E for short)have been regarded as the important factors restricting social development.The rise of new energy industry has largely eased the social pressure brought by 3E problem.The development of photovoltaic industry is a key point of new energy industry.With the increasing proportion of photovoltaic industry in power supply,research on its related technologies is also on the agenda.For photovoltaic grid connected power generation system,the change of light intensity and temperature will affect the working performance of photovoltaic power station,and the failure of grid terminal will affect the power quality of power system.Therefore,while vigorously developing photovoltaic industry,all countries have designated relevant technical specifications,which require photovoltaic grid connected power generation system to have a certain low-voltage ride through ability.Firstly,this paper analyzes the structure of photovoltaic grid connected system,divides the system into a photovoltaic cell part,a boost circuit part and a inverter part.In the photovoltaic cell part,it introduces the energy source,establishes a simulation model,and selects disturbance observation method to realize Maximum Power Point Tracking(MPPT)technology to improve the utilization of electric energy;then builds Boost circuit to obtain the appropriate output voltage,analyzes the working principle of inverter;selects appropriate filter circuit,obtain the state equation under different fault characteristics;and finally uses the double closed-loop control structure based on voltage directional control to complete the construction of complete the three-phase photovoltaic grid connected power generation system simulation modelThis paper chooses to realize the low voltage ride through capability under the symmetrical fault condition of power grid.For the selection of the low voltage ride through control strategy,based on the study of the traditional control methods,according to their advantages and disadvantages,the method of the current inner loop based on PI control and the voltage outer loop control based on Active Disturbance Rejection Control(ADRC)were finally designed.The algorithm of ADRC is improved based on the effect of ADRC in photovoltaic grid connected power generation system,and a new nonlinear function is designed to improve the ability of the controller to suppress signal oscillation and further improve the control performance of the controller.Through MATLAB simulation,the voltage and current waveforms of grid connected system are obtained.the results show that the improved algorithm can achieve the effect of suppressing high-frequency oscillations,and has a good control effect in accelerating control speed and suppressing external interference.The current fluctuation caused by voltage drop is also effectively solved,which realizes the operation of photovoltaic power plant without off grid and enhances the safety performance of grid connected system.On the basis of MATLAB simulation,a hardware experiment platform is used to verify the practical application effect of the algorithm on current fluctuation suppression.First,the PSIM software is used to connect the analog circuit in Simcode mode,and export the circuit to the.C language.control program.Then,the CCS software is used to import the program into the three-phase inverter hardware experimental cabinet with DSP chip as the controller,observe the experimental waveform,and study the control effect.The experimental results show that the waveforms obtained by the control strategy designed in the hardware equipment is basically the same as the those of the simulated waveforms,and the control effect is almost the same,which indicates that the control algorithm studied in this paper has certain theoretical and practical significance.Figure[54]Table[3]Reference[70]...