Development And Experimental Research On Metering Performance Calibration Device Of Analog Signal Input Merging Unit

Due to the environment where the analog signal input merging unit runs is very complicated and the entrance testing is not comprehensive, some problems related to the metering performance have emerged in the course of using, such as accuracy is not high enough, inter channel synchronization error is large and so on. Considering the metering performance of the analog signal input merging unit, this paper studies the metering performance test items and method of merging unit according to the Testing Specification for Metering Performance of Merging Unit with Analog Input released by the State Grid Corporation recently, and then proposes the overall scheme of the metering performance calibration of the analog signal input merging unit.The analog signal input merging unit calibration software is the key part of analog signal input merging unit metering performance calibration. This paper studies five aspects of the software development of the analog signal input merging unit metering performance calibration, including the overall software structure design, the design of high accuracy output power source, the design of data acquisition system, the phase error compensation based on Time-to-digital converter and the software algorithm design of calibration system. This paper describes and analyzes the first four problems and designs the corresponding solutions at first. And then studies the software algorithm alone by proposing ordinary FFT algorithm, single line interpolation FFT algorithm with Hanning window and two-line interpolation FFT algorithm with Blackman window. This paper codes, debugs and simulates these three kinds of algorithms by using Lab VIEW language, then compares the advantages and disadvantages of the three algorithms based on the simulation results, and ultimately determines the two-line interpolation FFT algorithm with Blackman window which has the highest computational accuracy as the analog input merging unit calibration system software algorithm.The analog input merging unit metering performance calibration device has been carried out some calibration tests in the national high voltage metering station. The test results show that the overall accuracy can reach 0.05 levels that could be used to check the analog input merging unit which is 0.2 levels or below 0.2 levels.Finally, this paper tests the performance of four different merging units and makes a statistical analysis of the test results by using the analog input merging unit metering performance calibration device, then obtains the relevant conclusions of analog input merging unit metering performance test, including the long-term stability of analog signal input merging unit is poor, there are bad configuration parameters in the configuration, multiple channel between the synchronous sampling accuracy should be improved, there are some problems in the time performance test and so on.