Research On The Detection And Control Of Voltage Sag

With the rapid development of industrial technology and national economics, power quality has become an important index that every department of electrical companies pays much attention to. With the forming and boosting of electricity market reformation, the utility must meet the increasing requirement of not only power quantity but also power quality from customer.Voltage sag is one of the most important parts of electrical index, the electrical companies all around nation pay more attention to the voltage sag than the other power quality events. Especially, with the rapid development of high technology and information economy lately five to ten years, all kinds of electrical equipments based on computer have been applied. These electrical equipments are very sensitivity to the voltage sags. For the above reason, it is essential to lucubrate the voltage sags, especially, focusing on the sag detective and control strategies. This research has not only theoretic meaning but also obvious practical value. As the effective and economic means to suppress the voltage sags, Dynamic Voltage Restorer(DVR) is the emphases of this paper. For the better performance of voltage compensation, this paper has do a lot work focusing on the detection and control of DVR.At first, following introducing the d-q transformation based on instantaneous reactive power theory, this paper proposed a novel detection method to voltage sags. The proposed method need to generate reference voltage which is always in-phase with the grid. By this method we can get rid of Phase-Locked-Loop(PLL), and the re-synchronization is not necessary. Using the new space vector coordinate, we also...