Simulation Research On Voltage Sag Source Identifying

With the wide application of modern power electronics equipments, more and more attention from both electrical engineers and customers is increasingly paid to the voltage sags as one of the power quality problems. There is great deal of significance on changing the relationship between the customers and utilities together with improving power quality to identify the sources of voltage sag accurately.In this paper, the characteristics of voltage sags are generalized based on the analysis of the three causes which are short circuit faults, induction motor starting and transformer saturation. With the theoretical analysis and the simulation results of MATLAB/ SIMULINK, researches are done for the propagation characteristics of sags among different voltage levels, and a method to identify the disturbance source of sag is proposed based on voltage sag energy and the correlativity of busbar voltage and current. A method of identifying the cause of sag is also presented by introducing second harmonics voltage, sag-ending amplitude information and aerial-mode of fault current. Simulation tests verify the feasibility of proposed methods.