Research On A New Type Of Electronic Hybrid Voltage/Current Transformer

High quality and stable operation of power system is an important foundation for the healthy and rapid development of national economy.Electronic transformer is the key device for energy measurement and relay protection in the electric power system.Because of the rapidly development of power electronics,electronic transformer has substituted for the conventional electromagnetic transformer gradually in the view of its many kinds of merits,and play an important role in high voltage intelligence power network.Based on the consideration of equipment integration,combined electronic transformer has been developed of a high degree in recent years.But there are still many problems in integrated,intelligent devices and programs to supply energy to high voltage side.Based on the existing power supply programs of electronic transformer high voltage side,combined with the actual application situation,a new way to supply power to high voltage side based on capacitor divider is proposed in this paper.The parameters’calculation formula of capacitor divider was derived through theoretical analysis,and then parameters were calculated with a 220kV transformer as sample.The design was verified through electronic circuit simulation.The function of transformer include monitoring the active power and waveform of voltage and current,measurement RMS of voltage and current.In this paper electric parameters measurement module was designed,electronic measurement circuit of cable parameters located in the high voltage side of the transformer.Voltage signal is gotten from capacitor divider and current signal from Rogowski coil.The high voltage side measurement circuit is composed of ASIC ADE7753 and SCM STC89C52,and the SPI communication between ASIC and SCM realized by programming.An experiment circuit board was made in view of the measurement module,which can communicate with the host computer through serial interface.To realize the measurement and waveform display,a virtual instrument was designed by graph language software LabVIEW.Optical fiber transmission system was used in practical application of electronic transformer to complete data transmission between high voltage side and low voltage side.At the end of this paper,optical fiber transmission system has introduced briefly,optical transmission system hardware and interface circuit was designed.Through case analysis and simulation,the proposed scheme to supply power to transformer high voltage side was proved to be correct.The measurement module was verified to be effective in measurement of bus parameters and communication with computer.