Research On Undesired Harmonic Current Suppression Strategy Of Single-phase Shunt Active Power Filter

As one of the main forms of energy in today's society,electric energy plays an irreplaceable role in our daily life.With more and more non-linear power equipments connecting to the grid system,the power quality of the grid system is seriously threatened.Active power filter,as an important device to improve power quality,the quality of output current has a great effect on the compensation effect.In this thesis,the undesired harmonic current suppression strategy of single-phase shunt active power filter is studied.Firstly,the continuous domain and discrete domain mathematical models of single-phase shunt active power filter are established,and the accuracy of the related mathematical models is verified.Then,the mechanism of harmonic current generated by dead-time effect is analyzed.Compensation strategies based on eliminating disturbance source and controller are proposed,and the applicable scope of corresponding methods is summarized.The characteristics of PCPR controller are analyzed emphatically,and a compensation phase design method based on the placement of closed-loop zero-poles is proposed to increase frequency range of compensated harmonic current and improve system dynamic performance.Besides,the distribution of switching harmonic current under different modulation modes is studied.The filtering performance of L,LCL,LLCL,LTCL switching harmonic filters is compared and analyzed,parallel RC passive damping is used to suppress the resonant peak.And the phase-shifting mechanism of switching harmonic elimination under different modulation modes is deduced in detail and the general law of phase-shifting angle is summarized.Finally,simulation circuit and physical experimental platform for single-phase shunt active power filter are built,and replication experiments are carried out according to the relevant conclusions in this thesis.The results show that the proposed strategies for suppressing harmonic current caused by dead-time effect and harmonic current caused by switches are effective.