Research On Three-phase Three-wire Shunt Active Power Filter

With the development of modern power electronics technology,more and more power electronic devices have put into our production and life,and help creating a huge benefit to our social life,but it also seriously polluted the power grid.The active power filter can effectively control the power grid harmonics and improve the power supply quality of the grid.Now,active power filter is being widely concerned and studied.Aiming at the three-phase three-wire shunt active power filter,in order to make full use of its characteristics and advantages and expand its application field,its compensation performance is researched in this paper.A new control strategy without harmonic detection is adopted,and this control strategy eliminates the detection of harmonics and reactive current,which directly extracts the current of the grid.It reduces the number of required current transformers and complex harmonic and reactive power unit,it can get higher compensation accuracy and dynamic response speed.This new control strategy consists of two control loops: grid current control loop and DC voltage control loop,and the grid current loop uses to regulate the grid current,the DC voltage loop uses to adjust the DC side voltage.The effectiveness of the control strategy is verified by simulation results.Then,for the public grid application of the general voltage source and current source type of nonlinear load,the harmonic compensation characteristics of these two types of nonlinear loads are analyzed.The unified expression of the harmonic current amplification effect is deduced,and the reason that shunt active power filter is not suitable for compensating the voltage source nonlinear load is found.In this paper,the solution to suppress the harmonic current amplification effect from the control strategy and the system structure is proposed,which ensures good compensation performance for shunt active power filter.The correctness of the theoretical analysis and the proposed solution are verified by simulation results.Finally,the active power filter experimental prototype was built,and the main circuit hardware selection and the system hardware and software of the prototype were introduced and designed.And the experimental results show that the prototype is effective and can improve the current quality of the grid.It is hoped that the research work of this paper will promote the practical application of shunt active power filter.