Large bandwidth compensation of current transformers

Power quality analyses in the last years has assumed more and more heaviness in industrial environments, due to the presence of non-linear and unbalanced loads: they require measuring instrumentation with large bandwidth. Since voltage and current transducers are the first part of a measurement chain, they must have frequency bandwidth sufficient for analyzing conducted disturbances on power system. Voltage and current transformers (VT and CT), which are the most installed transducers in electrical power system, are typically constructed to operate at industrial frequency, 50/60 Hz, but it is clear that their substitution would require an unsustainable cost. Therefore in this paper the realization and metrological characterization of and electronic device for extension of CT operating frequency bandwidth is presented. It is based on field programmable gate array, which implements in real time a digital compensation technique. The compensated CT continues to be an analog device since the FPGA board is opportunely equipped with analog to digital and digital to analog converters.