Research On Passive Theory Control Strategy Based Of Grid-connected PV Inverter In Weak Grid

With the increasing depletion of non-renewable resources and environmental issues,people are paying more and more attention to renewable energ y.Photovoltaic power generation has received extensive attention in the wave of new energy development since it is clean,pollution-free and inexhaustible.In recent years,the photovoltaic power generation industry has continued its explosive growth,pushing the solar power industry to the fast track of rapid development.How to make the inverter still safe and effective in the weak grid environment where the grid environment is relatively harsh has become a research hotspot at this stage.This paper,based on the weak grid environment,takes the single-phase grid-connected inverter as the object and studies the photovoltaic grid-connected inverter control strategy based on the passive theory to improve the power quality and dynamic response speed of photovoltaic power generation systems.First of all,in this paper,the Euler-Lagrange model of the grid-connected inverter is deduced and analyzed for the weak grid environment.An improved passivity-based control strategy based on quasi-PR control is proposed to solve the problem that traditional passive controllers have unfavorable grid-connected current quality and large THD values.Secondly,based on the improved passivity-based control of the current inner loop,the power feedforward link is introduced to the given current in the double closed loop of the inverter.This power feedforward control method can realize fast tracking of the output power of the photovoltaic array and improve the adaptability and response speed of the system to the time-varying pre-stage power output.Furthermore,in view of the voltage instability at the grid-connected point that may occur in a weak grid environment,a power output control method based on grid line impedance ratio is proposed.Under the condition of certain inverter capacity,the active and non-output of the inverter output is reasonably distributed to achieve the maximum support for the grid voltage.This paper sets up a single-phase photovoltaic grid-connected inverter simulation model in MATLAB/Simulink to verify the correctness of the proposed control strategy.Finally,the single-phase grid-connected photovoltaic grid-connected inverter experimental platform was established.The experimental results of the grid-connected inverter control strategy proposed in this paper were verified experimentally,and the improved passive control proposed in this paper was demonstrated.The superiority of strategy,power feed forward double closed loop control strategy and inverter output power control strategy..