The Control Of Flux Of Transformer In Dynamic Voltage Restorer

Dynamic Voltage Restorer (DVR) is mainly used to protect sensitive loads from theeffect of power voltage drop, usually through a coupling transformer connected in seriesbetween the grid and the sensitive load. This leads to easy to make a transformer saturationwhich will cause inrush current problems when DVR starts.To solve this problem, it isusually twice the rated transformer core design, which will make greatly increased the sizeand cost of transformer.In order to better suppress the inrush current generation, this article make anembedded analysis for the transformer flux observer program, comparing the accuracy ofthe observation schemes and chose a suitable scheme for transformer flux observation. Atthe same time, the traditional techniques for inrush current mitigation are compared and animproved method of inrush current mitigation is proposed to solve the limitations oftraditional methods. This method which is verified by the experiment is a good solution fortransformer inrush current suppression, and can effectively regulate the DC component ofthe transformer flux. Finally, based on observation of transformer flux, drawing on thevoltage and current loop control system, the three loops control strategy is designedincluding voltage, current, flux as state variables, by adopting the limiter of flux and thefeed-forward of flux to control the transformer flux. Simulation results show that thesystem achieved a good suppressive effect of inrush current and can effectively regulate theDC component of the transformer flux, and the stability and dynamic performance,robustness of the System is capable to the requirement of voltage compensation of DVR.