"Three-point" Arithmetic for Amendment AC Sampling of Fundamental Wave Frequency in Power System

In modern power system,digital real time measurement is widely used in electric measurement,terminal end of distribution power automation;relay protection;fault oscilloscope and other automatic equipments.Consequently,the precision of system voltage,current and other electric parameters' accurate measurement is very important to the automatic operation of power system.The variation of frequency in power system would bring some errors both in data acquisition and measurement;so,the sampling frequency must be amended during the process of data sampling.There are two methods of hardware and software common used in frequency measuring and tracing,while,each method has its advantages and disadvantages respectively.On the side of hardware,"Three-Point" arithmetic is proposed to amend AC sampling of fundamental wave frequency in power system.Principle of this arithmetic is deduced,static simulation is made,its merits and faults are analyzed too.The precision of frequency measurement is analyzed,and the comparison is made with hardware method and other software methods,conclusion can be drawn that this method is very effective in amending fundamental wave frequency.Singular points and random data's elimination of the function is pointed out too,which is related to the frequency emendation.Finally,a simple example in practical engineering project is produced and analyzed,and engineering need can be satisfied.Analysis results show that this arithmetic can improve the measurement accuracy of system fundamental wave voltage and current.Working with suitable wave filters,it can be used at some places where data measurement strictly need in real time.