Research On Voltage Sag Influence The Sensitive Load And Control Measures

With the rapid development of economy, all kinds of sensitive load are used more and more widely in the industry. These loads require high quality of electric power, especially the voltage of the amplitude. The influence of these load always need higher quality of voltage amplitude than usual load. Voltage sag almost can say is the most important reason that made those sensitive loads cannot use as usual. Voltage sag being unpredictability, it can be started by a large induction motor startup, transformer put into operation and power system fault. What’s more, electric power system short circuit fault is the main reason that cause of voltage sag. With more and more industrial production affected by the voltage sag, many power sector has deeply researched on susceptibility problems between electrical equipment and voltage sag.The research are significant in both theory and practice. This article has introduced the research on the voltage sag influence on the sensitive load in detail. This article mainly analysis the cause of voltage sag, how the voltage sag influence the sensitive load and study on the degree of sensitive load affected by voltage sag. At last, we choose the Dynamic Voltage Restorer (DVR) to restrain the voltage sag according to comparing with the measure in home and abroad.Dynamic Voltage Restorer cost little and it work quickly that proved it to be the most important device to restrain voltage sag by the global power industry attention.This paper has research on the Dynamic Voltage Restorer. This paper also discussed the DVR working principle and its research meaning. At the same time the part of the energy storage device, inverter device, transformer and filter of DVR are introduced in this paper.The time of voltage sag is short, so the fast detection is the key to restrain the voltage sag. This paper has discussed the development and application of test method in detail, and also has introduced some new detection methods. Finally, the designs decide to adopt a single-phase to three-phase dqO of virtual transform method which has used maturely in the engineering application, and use the MATLAB simulation proves the validity of the test method work.The voltage sag is always happen in single phase, this article has used the MATLAB/SIMULINK software to establish the model of single-phase DVR which based on the study of the theory. In this design single-phase DVR simulation model, we use the rapid feed-forward control, and the minimum voltage compensation method to compensate the load voltage. Then the simulation experiment also has proved DVR can restrain the load voltage sag well. In order to have better result on the side of the load voltage compensation, this paper use the dynamic voltage restorer with other compensation methods to restrain the voltage sag, and finally adopted two DVR in series as the method to restrain the voltage sag. The simulation results prove that the two DVR in series has the good detection method and the control strategy, and achieved in the good compensation at last.At last this design has analysis in the simulation results.and make some improvement measures to achieve better result. We make the detection system interlock to control the DVR when it begin to put into operation in the first one sixth of power frequency time.in order to prevent the DVR caused the load voltage too high when the detection system was just put into operation within the3.3ms, so we delay the detection measure control the DVR, and the simulation results the effectiveness of the method.