The Research Of Non-series Transformer Dynamic Voltage Restorer In Voltage Sags Detection And Control Strategies

With the advances of high technology and the development of the information industry, a large number of equipments which are sensitive to power quality are put into use, and these devices require high quality of power supply. Among many kinds of dynamic power quality problems, the voltage drop is a category that occurs most frequently and leads to most serious harm. Dynamic Voltage Restorer(DVR) has been considered to be a costeffective custom power device, which alleviates voltage sags. Based on the DVR, the paper do some research on the voltage sag detection and control method for inverter.Based on the analysis the principle and main circuit of DVR, the paper studied several common strategy for the voltage compensation of DVR. Then, the paper discusses and designs the main components of the DVR, and confirms the main circuit of no-series dynamic voltage restore for research.Secondly, this paper analysis the methods used in voltage sag detection, and points out their deficiencies. According to the boundary effect problem of the Hilbert-Huang transform(HHT), the improved HHT is applied to deal with the non-stationary voltage sag signals. The detecting effect is proved to be satisfactory and better than HHT.Finally, this paper established UDVR S equivalent circuit and math model. By reason of shortage of the voltage, current double closed loop PI control, a model-free control was used as a compensation to form a multiplexed control method. In the MATIAB/SIMUUNK to create simulation model, the simulation results show that the composite control method has great speed and excellent steady accuracy.