A Virtual Instrument for the Electric Power Monitoring in the Distributing Network

This work proposes a virtual instrument (VI) for the electric power quality monitoring aiming to act in real-time for detecting, monitoring and recording all typical disturbances superimposed on the ideal signal; it is based on both IEC standards 61000-4-30 and 61000-4-7 [1] [2] and on the directive for the Consultation of the Italian Authority for the Electric Power and Gas of April 6, 2005. The latter presents the peculiar features of an experimental monitoring system for the mid voltage electric energy distribution network whose experimentation should lead the distributing companies to the respect of the Voltage Quality (VQ) monitoring obligation. According to the bove mentioned regulations, the proposed VI acquires both line voltage and current waveforms and carries out the innovating power quality indexes calculations in times comparable with those of other commercially available nstruments; in order to obtain an accurate estimation of the parameters of interest a suitable Fast Fourier Transform interpolation algorithm is implemented in the VI. The laboratory prototype is based on a low cost data cquisition card equipped with suitable current and voltage sensors; the VI code is developed using National Instruments LabVIEW Professional Development System and Mathworks MATLAB and achieves very interesting performances.