Research On Power Quality Control Strategy Incorporating Distributed Generation

With the global energy crisis and environmental issues have become increasingly prominent,distributed power more and more importance to social,such as photovoltaic power generation.Most distributed power through grid inverter access to the power grid,due to distributed power has the characteristics of randomness and volatility,the capacity of grid inverter is often designed according the maximum power,this makes the capacity of the inverter underutilized to a large extent.On the other hand,with the continuous development of modern industry,more and more non-linear and impact load access to the grid,harmonic and reactive current pollution to the grid more and more serious.In this situation,traditional power quality control devices have been increasingly unable to meet the requirements of power quality,active power filter became an effective means of solving harmonic problem,while APF is difficult to widely used because its high cost and single function.For their shortcomings,and considering the similarity in structures,using functions and control methods of the grid-connected inverter and active power filter,a unified control strategy is proposed.Firstly,a detailed analysis is made to structure and working principle of the unified control system,analysis and comparison the inverter mathematical model under various forms of coordinates.Based on this,synchronization technology,harmonic and reactive current detection,voltage and current control method,command current synthesis method based capacity limitation are designed for the system.Through above design,the system can be controlled in the revolving coordinate reference frame.Using this unified control strategy,grid-connected generation,harmonics suppression and reactive power compensation are achieved at the same device,which exerts the advantage of distributed generation,and improves grid power quality.Then,switching frequency,DC voltage and capacitance values and parameters of LCL filter circuit are designed.In this process,parameter design of LCL filter circuit are depth analysis.Finally,in order to verify the validity of the control strategy and accuracy of the selected parameters,using MATLAB / Simulink build simulation model,simulation analysis are made in different working mode of the system.