Study Of Dynamic Voltage Compensation Technology For Distribution Network End Based On DVR

As the end of whole power system,the power quality of distribution network is the key for the electric equipment of the user to run normally.Especially,the dynamic voltage quality,for instance voltage sags,voltage instantaneous interruption,voltage swell and so on,seriously affects the normal work of the sensitive load and then cause huge economic loss to production.As a result,in order to guarantee the normal operation of the sensitive load,the dynamic voltage compensation technology for distribution network based on dynamic voltage restorer(DVR)has a great significance.As a power electronic device,DVR has great impact on solving voltage quality,compensate the voltage accurately and quickly and guarantee the normal operation of the load.This dissertation proposes a new topology of DVR and modified software phase-locked loop(SPLL)based on double second order generalized integrator(DSOGI)and studies its theory in-depth.The simulation platform has been built based on the new topology of DVR.Considering the practical application fully,in case of voltage sag with phase jump,harmonic or unbalanced three-phase voltage,conduct some experiments.The simulation results proved that the voltage signal can be detected accurately and quickly according to the modified SPLL.Meanwhile,the harmonic distortion rate of output voltage of new DVR is lower and more close to the standard sine wave.This dissertation establishes the mathematical model of DVR.Firstly,analyzing the advantages and disadvantages of feed-forward control in DVR control system;secondly,analyzing the advantages of composite control in DVR control system.Through theoretical analysis and simulation,the composite control strategy can perfectly realize the dynamic voltage compensation of DVR for distribution network.Finally,based on the modified software phase locked loop,this dissertation uses reactive power based DQ transform to detect voltage sag.Based on the whole DVR simulation platform,it verified that DVR can achieve voltage compensation quickly and accurately under unbalanced three-phase voltage or harmonic condition.On the basis of theoretical analysis and simulation,designed the whole plan of the system;taking the control chip TMS320F28335 as the core,designed the control circuit and main circuit;gave the algorithm flow chart relying on the practical hardware circuit and completed relative experiments.The experimental results show that the new topology of the DVR can reduce the voltage level of the DC-link and the harmonic distortion rate of output voltage.