Study On The Tracing Method And Device Of Analog-input Merging Unit Testing Equipment

With the wide use of analog input merging unit in intelligent substation,in order to avoid the measurement error caused by the poor performance of analog input merging unit,various kinds of merging unit testing equipment have been widely used.In order to establish a reliable value transfer system for merging units,it is of great significance to verify the functional reliability and traceability of the merging unit testing equipment by using reasonable and reliable traceability methods and detection devices.In this paper,the existing traceability methods of merging unit testing equipment are studied.It is found that the current traceability methods for merging unit testing equipment following the traditional transformer calibration are obvious limitations in theory and method.Therefore,referring to the new"Technical Specification for Merging Unit Testing Equipment",this paper studies the testing items and traceability methods of existing analog input merging unit testing equipment,and proposes a general scheme for performance testing and accuracy traceability of analog input merging unit testing equipment.In this paper,two parts of analog merging unit traceability experiment are studied including analog traceability and time performance experiment,and the corresponding test scheme is designed.For the analog traceability,a traceability method based on digital differential method for merging unit testing equipment is proposed.Compared with the existing traceability method,it has the advantages of higher theoretical accuracy,better accuracy stability and simpler structure.In the part of time performance traceability,three test schemes are designed.On this basis,a virtual standard merging unit is constructed based on virtual instrument technology.As a traceability device of merging unit testing equipment,it can complete traceability calibration test conveniently and quickly.Considering that the existing calibration tests generally do not consider the risk of uncertainty of standard instruments to the reliability of test results,in order to establish a reliable system of traceability,this paper establishes a probability model for reliability analysis of calibration results,which can use the uncertainty ratio between the tested instrument and the standard test equipment to calculate the reliability of the test results while giving the test results,and it is conducive to the establishment of a more reliable quantities chain.Finally,the test device proposed is verified.The measurement accuracy of the analog test platform built in this paper meets the level of 0.02,the expanded uncertainty of the magnitude difference is 1.2×10^-4,and the expanded uncertainty of the angle difference is0.4?.It can trace the source of the analog input merging unit tester with the accuracy level of 0.05 or less.At the same time,the basic analog measurement and time performance test of an analog input merging unit tester are carried out,and the reliability of the test results is analyzed,which proves that the traceability method and device have important application value.