Metrology and Measurement Systems

With the diffusion of non-linear and unbalanced loads, which often cause unacceptable quality level of energy, energy quality monitoring represents an increasing need. Analyzing conducted disturbances requires measuring instrumentation, and thus voltage and current transducers, with large bandwidth. Voltage and current transformers (CT) are the most often installed transducers in electrical power system and typically they are 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 a digital technique for the compensation of CT, based on field programmable gate array, is presented: it implements a digital filter with a frequency response equal to the inverse one of the CT. The compensated CT continues to be an analog device since the FPGA board is opportunely equipped with analog-to-digital and digitalto-analog converters.