Study On Data Acquisition System Of GIS Electronic Transformer

With the improvement of the transmission line voltage level and construction of the“strong and smart grid”, transformer, which plays an important role of the power system incontrol, protection and measurement, has been proposed a higher demand. Traditionaltransformer, which has shortcomings of the narrow band, the smaller linear range and thecomplex insulation, will not adapt to a digital, intelligent power system in the future; However,the newly electronic transformer can not only overcome the shortcomings of the traditionaltransformer, but also has some advantages, such as better safety, lower cost and higheraccuracy.For those reasons, the newly electronic transformer has become the hot point ofcurrent intelligent electrical equipment research in this filed. Thus, the electronic transformerwill be bound to replace the traditional electromagnetic transformer and play an importantrole in the power system.In this paper, the designer took advantage of a successfully developed GIS electronictransformer prototype as the secondary side signal input, and based on the requestments ofnational institude standards of GB/T20840.7-2007and GB/T20840.8-2007to achieve thefunction of data acquisition.The main work includes two aspects: the hardware design andsoftware processing.The hardware circuit design includes signal anti-aliasing filter circuit (AAF), the voltagefollower circuit, analog integrator circuit, A/D control circuit, FPGA peripheral circuit design,etc.In order to save costs and improve design efficiency and shorten the design cycle, thepaper firstly used the OrCad Capture software to simulate the function of the circuits; andthen made PCB printed board to test actually.In this process, the paper also tookelectromagnetic compatibility (EMC) into account.The software design includes the Fir-type anti-aliasing, digital integrator, asynchronousserial port communication (UART), the CRC checksum, etc.Firstly, the paper used QuartusⅡsoftware of Altera Corporation to write description language, and use DSP Builder softwareand Modelsim software to simulate and debug; Lastly, download the configuration file toFPGA chip to actually run and use SignalTapⅡ logic analyzer or digital storage oscilloscopeto observe actually.Finally,the author has used calibration device to calibrate the function and itsaccuracy.The results show that the GIS voltage electronic transformer prototype sensor couldmeet the requirement of GB/T20840.7-2007,the measuring accuracy class could reach0.2andthe protective accuracy class could reach3P;The GIS current electronic transformer prototypesensor could meet the requirement of GB/T20840.8-2007,the measuring accuracy class couldreach0.1and the protective accuracy class could reach5P.