Study On Estimation Algorithm Of Voltage Sag Area Based On The Reconfiguration Method Of Proportional Interpolation Retrieval System

With the progress of modern science and technology and the rapid development of national economy,the power quality problem more and more get the attention of power department and users.Among them,voltage sag caused by all kinds of fault is a major reason why sensitive equipment can not work normally,it will cause severe economic losses.Because voltage sags area can be used as the important judgment of sensitive equipment whether the voltage sag happens under the condition of fault,so now more and more experts and institutions are in studies to the method of determining the area of voltage sags.There are two major categories of the analysis methods of the voltage sags area: the measured statistics method and random forecast method.The measured statistics method has a long cycle,and need to install more measurement equipment so that we have to pay higher cost.Meanwhile,the measured results has a great contingency.With such big shortcomings,the random forecast method is more used in practical.There are four types of sag area estimation method considered feasible: critical distance method,fault point method,the critical distance and fault point method and the interpolation fault point method.For different working conditions,these methods have some shortcomings and deficiencies.Therefore,a method of voltage sag area estimation based on system reconfiguration method with proportional interpolation is put forward.Research and analysis the effectiveness of the method to improve forecast precision of voltage sag area.The main work content is as follows:First of all,the waveform of voltage sag when all kinds of voltage sag source happens is got through the experiment.Analyze each waveform characteristics of voltage sag and its influence to the voltage sag.It is concluded that short circuit is the most serious and the main reason of voltage sag.Secondly,Voltage sag characteristics detection algorithm are discussed and the advantages and disadvantages of various algorithms are pointed out.On the basis of detailed research and analysis of the traditional domain of voltage sag estimation method,the paper points out their respective advantages and disadvantages so that to put forward an improved sag area estimation method.The analysis of the relationship between voltage sag duration and phase jump with the sag area is given.Considering the two characteristics,it gives the modification method of sag area.Again,this paper proposes a method of voltage sag area estimation based on system reconfiguration method with proportional interpolation.The position of the interpolation points is studied in order to get it's influence on the interpolation function.On this basis,the method of choosing the interpolation point(failure point)applied to the forecast for voltage sag area is given.This paper has carried on the system reconstruction method of theoretical derivation and gives the method of combining it with the proportional interpolation method.Finally,in the IEEE-39 node standard test system,the method of voltage sag area estimation based on system reconfiguration method with proportional interpolation is simulated.By contrast with traditional voltage sag area forecast method,this experimental simulation proves the improvement of the new method to sag area forecast accuracy.Considering the voltage sag duration and phase jump,the experiment simulates the forecast of sag area and discusses their influence on eventual forecast results sag.For different fault types and different voltage sag upper limit,the results of voltage sag area estimation are given.These research and analysis have a certain guiding significance for selecting rational power system operation mode and choosing important load's location.