Calibration System For The Digital Output Of Electronic Transformer

As one of the major electrical equipments of a digital substation, electronictransformers have been widely used. According to output modes, Electronic transformersare divided into analog output and digital output electronic transformer. As a transitionalform, Analog output is to use the existing interface in the substation. Digital output willeventually be replaced with analog output. Therefore, the digital output of electronictransformer has become a new hot spot. The widely used of digital output electronictransformers develop the research of calibration system for electronic transformer withdigital output. The research of calibration system is important to the accuracy and stabilityof the digital output of electronic transformer.In this paper, electronic transformer’s digital output characteristics and communicationcharacteristics are first introduced. Then, a high accuracy (accuracy of0.05) calibrationsystem which meet the requirement of digital output electronic transformer and on-siteverification is designed by verify principle of the direct comparison. The portablehigh-precision(24-bit resolution) data acquisition card of U.S. NI’S is used as a standardacquisition unit of calibration system, ensure the accuracy of calibration system. Developedby the PCI card which generate synchronization pulse, it ensures synchronous sampling oftwo-channel of calibration system. In this paper, mainly study on sampled values packetsbased on IEC61850-9-1communication protocol and the data frame structure. In the part ofcalibration system software design introduce data reception, obtaining synchronoussampling point, error calculation and so on. then we describes accuracy test of thecalibration system. In the end, we discuss the error analysis and data processing methodsapplication in test data of calibration system. and to conduct error analysis and stochasticprocesses eigenvalue estimates for the test data of calibration system. At last, theuncertainty of the calibration system is analyzed.The calibration system meet the design requirements, through the accuracy test innational high-voltage measurement station, with the overall calibration method, Theaccuracy of calibration system reaches0.05accuracy.