Research On Calibration Technology Of Electronic Transformers

With the rapid development of digital substation, its electronic transformer to overcome the advantages of the traditional electromagnetic transformer's insulation and magnetic saturation occupy an important place in the digital substation. How to accurately test electronic transformers is of great significance for electric power system protective relaying, metering and control system.This paper first introduces the electronic transformer and check system and the basic principles of their development. In accordance with IEC60044-7/-8 and IEC61850-9 standards, a detailed analysis about the digital output of the electronic transformer was introduced, and the design of check system hardware and software was proposed. In terms of the use of virtual instrument technology, the author developed the check system engineering on the basis of the LabVIEW8.6 software. The high-accuracy multimeter, Agilent3458A, is the basis of hardware design, which completing signal acquisition, conditioning and data upload etc. On that basis, the paper focused on analysis of the following aspects:1. About communication, the check system analysed IEC61850 9-1 standards and GPIB communication protocol, at the same time introduced the connection between the multimeter and the check systems.2. The author Introduced IIR, FIR digital filter design and their application in the check system, and then analysed electrical parameters computational method about amplitude, phase and frequency. According to the characteristics of signal detection and system design requirements, the author designed zero-phase shift filter and DFT interpolation method based on the Hanning window to calculate the electrical parameters, and analyze their characteristics and simulation results.3. Using of more high-precision equipment FLUKE 5720A, BHE-type transformer standard to test the design of check system, and according to the simulation results, the author demonstrated the feasibility of the check system.4. The author introduced the practical applications in the Field test, and analysed its error in accordance with the result of Field testing.The purpose of check system is testing electronic transformers'phase and amplitude, heightening the reliability of digital substations, and providing the basis for relaying, monitoring and control system, and to achieve stable operation of power systems. With the development of IEC61850 standards and the electronic transformer and its check system standards, the system should make the necessary updates and further study, in order to adapt to the development of power system.