Research On Voltage Sags Evaluation Method Based On Energy Function

Automation devices such as computer systems and microprocessors are widely used in actual production.These devices have increased productivity,but the requirements for power quality have become more stringent,especially for voltage sags.The voltage dip as one of the power quality problems has brought huge economic losses to the manufacturing industry and has received increasing attention from people.It is particularly important to correctly understand voltage dips and accurately assess voltage sags.Based on the existing research on voltage sags event evaluation methods,this paper proposes a method to evaluate the effect of voltage sags on the basis of energy function.This paper analyzes the mechanism under the influence of voltage sags on three typical sensitive devices.In this paper,the equivalent circuit of the AC contactor is given,and the influence of the sag amplitude,duration,and the starting point of the sag on the tolerance of the contactor is analyzed;the circuit structure of switching power supply and frequency conversion governor is given.The influence of the starting point of sags,load capacity and voltage and current protection on DC capacitor storage is analyzed.Based on the analysis of the mechanism of the above typical sensitive equipment,this paper proposes a method for assessing the effect of voltage sags on the basis of the energy function.Energy-sensitive devices are defined.The representation of the energy function is given.The energy function is used to represent the voltage sag waveform and the corresponding device tolerance curve.By comparing the energy function curves,the influence status of the voltage sag event is evaluated.Simulation analysis illustrates the correctness of this method for assessing voltage sags.Aiming at the method of voltage dips assessment proposed in this paper,the experiment of the effect of voltage dips on the contactor and switching power supply was carried out to verify the correctness of this method.An experimental platform for testing the actual tolerance curve of sensitive equipment was set up,and an experimental scheme was formulated.According to the experimental scheme,the study was conducted on the actual withstand curve of the voltage sags of the contactor and the switching power supply under the influence of different parameters of temporary sagging.Falling characteristic parameters influence the actual tolerance curve of the contactor and the switching power supply;the voltage sag in the simulation example was tested on the experimental platform,and the contactor,switching power supply and programmable controller were tested experimentally.The results were compared with the evaluation results and the correctness of the evaluation method was further illustrated.