Research On Voltage Sag Source Location Method Based On Comprehensive Criterion

With the development of power electronics and computer technology,more and more sensitive loads are connected to the power system,which makes higher demands on the power quality of the power grid.Voltage sag is one of the most serious power quality problems of voltage sag source of accurate positioning is helpful to discover and eliminate the disturbance source in time,can also provide the basis for both sides responsibility involved is defined.This article first introduces several classic voltage sag source locating method of upstream and downstream,including the disturbance power and disturbance energy method,the system trajectory slope method,the current real component polarity method,the equivalent impedance of polarity method impedance relay and distance method,and analyzes the application scope of various methods.The single power radiation network is used to verify the simulation.Secondly,in view of several classic sag source locating method it is limited in scope,this paper extracted sag information of multiple characteristics as sample,in combination with the thought of RBF neural network classification,build a classifier,and through the gradient descent method to optimize,realize to the upstream and downstream of voltage sag source localization.Simulation results show that the accuracy of this method is significantly higher than that of several classical positioning methods.Finally,this paper combines the upstream and downstream positioning of voltage sag source with the idea of fault location to realize more accurate positioning of voltage sag source.This paper introduces the concept of node observable domain and uses YALMIP toolbox in MATLAB to optimize the configuration of monitoring points.A method of fault resistance prediction is introduced to reduce the influence of fault resistance change on the location of transient source.According to the observation area and the estimated fault resistance of the upstream and downstream location and monitoring points of the transient source,possible fault lines are determined.The virtual fault point is set on the possible fault line,and the accurate location of the transient source is realized according to the error analysis results of the calculated voltage amplitude and the actual value of the monitoring point.In this paper,IEEE9 node model is used for simulation verification.Simulation results show that this method can accurately locate the voltage sag source.