Research On Detection And Suppression Of The Harmoic In Microgrid

With the change of the energy structure and the enhancement of environmental p erception,the traditional p ower grid sy stem encountered a number of diff iculties.therefore the domestic and foreign r esearch ers gradu ally focus on the distributed generation sy stem,which is based on renewable energy.Distributed generation can enhance the reliability and stability of the network,but because of it 's imp act on the large grid,the p romotion and use of distributed p ower generation is restricted.The emergen ce of micro grid eff ectively allev iate the contradiction between the two grids,and the p ower quality and p ower efficien cy of the micro grid are increasin gly attracted worldwide attention.Due to the restriction of natural resource and the demand of environmental p rotection,the research of national micro grid is continuously increasing.Analy zation,detection and supp ression of the harmonic current are mainly studied to imp rove the p ower quality in the microgr id.First of all,the research of the workin g p rincip le of the micro grid inverter is carried out,and the three-p hase inverter is determined to be the main object.The p rincip le and app lication of PQ control,V/f control and SVPWM control are introduced.Based on the three control strategies,the model is built,which lay s a foundation for the d etection and supp ression of harmonics in the micro grid.Second ly,the supp ression scheme of harmonic current is divided into two asp ects: active harmon ic sup p ression and p assive harmonic supp ression.As to the p assive harmonic supp ression,three p hase p arallel vo ltage typ e APF is selected as the main object.Accordin g to the results of the p revious analysis,the control and driving strategies of APF are imp roved.The harmon ic detection method based on instant aneous reactive p ower theory to detect the harmonic curr ent is ap p lied as the instruction current op eration.The comp osite control of PI regulation and RP regulation is used as the curr ent trackin g control p art.The closed-loop control strategy is used to control the voltage of the DC side,and the SVPWM control strategy is used as the signal driv in g strategy,which dr ives the APF to p roduce the harmonic supp ression current.As to the active harmonic sup p ression,the control strategy of the inverter is imp roved,which can p lay a role in filterin g out p artial harmonics.Based on the instantaneous reactive p ower and harmonic d etection theory,the p urp ose of extract different frequency harmonic curr ents is achieved by chan gin g the filter's frequen cy.And then p ut forward the harmonic sy nthesis strategy of p ositive sequence and n egative sequen ce imp edance.The imp rovement of voltage control strategy realized the p urp ose of the active supp ression of harmonic curr ent in micro gr id.At last,the simulation model is used to simu late the h armonic curr ent supp ression scheme in micro gr id by MATLAB/Simulink software.The results show that the active and p assive harmonic current supp ression scheme used can effectively imp rove the current quality of the microgrid,which is feasib le in theory.