Uncertainty Evaluation of a THD Meter based on FPGA platform

In this paper we propose an instrument for the power quality monitoring, through the measure of PQ indexes (in particular we refer in this work to the THD index meter) and its characterization. The realized instrument is able to acquire the signal samples (opportunely conditioned) from the power network, to calculate the THD index and to estimate the uncertainty by which the last result is affected. The implementation makes use of a FPGA (field programmable gate array) Xilinx Virtex-II programmed in VHDL. This electronic device is a valid solution to speed, dissipated power and costs problems, and may be revisited every time the algorithm it implements becomes too obsolete (e.g. when new PQ indexes need to be substituted for old ones) or when one wants (for different needs) vary even one parameter of the structure. The utilized development system traduces the code (VHDL is a universal and highly compatible programming language) into the circuital specification that the platform has to assume