Voltage Sag And Simulation Of Detection Method

With the extensive application of modern power electronic devices, voltage sag has become important power quality problems power sectors and users increasingly concerned, which sets higher requests to the voltage quality of power supply system. Interruption or voltage sag of several cycles will impact normal work of these equipments and bring great damage. So it has become the most concerned power quality problem. Therefore, the exact, timely and fast detection of the characteristics of voltage sags can bring tremendous economic benefits and have a very important practical significance.This paper described the basic requirements, characteristics and classification of power quality and enormous significance of improving the power quality. In addition, this paper focused on one important aspect of the power quality problems——voltage sag, including its concept, causes, harms, monitoring and prediction and suppression methods and so on. On this basis, through analysing and comparing several kinds of voltage sag detection algorithms, we summed up the advantages and disadvantages of various algorithms and their applicable scope.At present, DVR (Dynamic Voltage Restorer) is an effective way to solve the problem of voltage sag. This paper introduced dq transformation andαβtransformation method used in the DVR commonly and an improved derivation detection method. Simulation results of two detection methods showed that the improved detection method had shorter delay and better waveform of detection and met the requirements of accuracy and timeliness better.