Voltage Sag Application Algorithm And Improved Topology For Dynamic Voltage Restorer

Due to the development of modern society and the progress of science andtechnology, the electric equipment of power and more complex sensitive load to beused, the power quality problems have become a more general issue in the grid.Dynamic Voltage Restorer (DVR) has good performance and lower prices. It is notonly compensate the voltage sag on the grid voltage, but also can help to solve theproblems about voltage processes, compensation for unbalanced three-phase gridharmonic pollution in series and etc on power quality.Dynamic Voltage Restorer (DVR) has widely used to compensation when thegrid voltage sag. But it is still need to improve. This paper introduces the basicconcepts of power quality, dynamic voltage restorer (DVR) structure andcompensation of the voltage sag. By analysis compensation method of dynamicvoltage restorer, Such as, effective value compensation method, the wavelettransform method, missing voltage technique and d-q transform method. Foundmissing voltage technique with a simple calculation, fast response. And then itimproved this method to make up its compensation limitations. A key lies in theimproved method is compare each sampling site and the theoretical voltage duringthe voltage sag. And this article is still improved full-bridge inverter topology ofDVR and push-pull inverter topology of DVR. The biggest advantages of thismethod is that no need to obtain the instantaneous phase angle and amplitude andable to compensate for unpredictable distortion of voltage sag, compared with othermethods, it has a great significance.To prove the feasibility of this approach, a simulation model of the simulationis builded in the simulat by SIMULINK. The simulation results show that thismethod can better solve the real-time and accuracy needed in the DVR. Thismethod has better practical significance to improve the power quality problems.