Design And Optimization Of Harmonic Detection Algorithm For Three-Level Parallel Active Power Filter

With the developments of new power transmission systems and electric vehicles industry,the requirements of current harmonics in industrial production is extreamly strict.Therefore,the filter that has a good performance will have a wide range of markets.The traditional passive filter has higher operating voltage level and relatively large compensation capacity.The active filter is generally 500V and below,the compensation capacity of which is relatively low.The active power filter can compensate for the size and frequency of harmonic changes,so there is a good potential market.In the low-voltage system,the load fluctuates more frequently and it fluctuates in a large range.At the same time,the compensation performance of the active filter is affected by the device parameters.Therefore,the aim of this paper is to optimize detection and control,and then to improve the performance when the filter's actual compensation capacity is lower than the rated capacity.Details of optimization are as follows.Firstly,if the system needs to correct power factor,the active filter improves its performance by increasing the actual compensation capacity,the added part is the reactive power of the specified capacity needed to be increased.Secondly,if the system only needs to compensate the harmonic current,the active filter reduces the effect of the ripple current caused by the small inductance of the grid through on-line optimization of system parameters.The performance is improved.In the three-level structure,for the control of the mid-point potential of the DC side,this paper proposes the mid-point average current of the DC side based on the existing research.And then re-design,optimize,to simplify the algorithm and improve the control effect.Finally,use MATLAB to build a simulation model to verify the optimization scheme proposed in this paper,and further validate the actual compensation effect through the physical model.