A PC-Based Wattmeter for Accurate Measurements in Sinusoidal and Distorted Conditions: Setup and Experimental Characterization

Abstract

This paper presents the development of a highaccuracy sampling wattmeter, which can be employed with both sinusoidal and distorted input signals. The proposed personal computer (PC)-based system is a simple, portable, and low-cost solution because it is based on two commercial data acquisition boards connected to a common PC. Owing to this solution, the voltage is sensed directly, avoiding expensive voltage dividers, while the current is sensed by means of a noninductive current shunt. Commercial software is also used for data processing and implementation of the virtual instrument. The setup of the PC-based wattmeter is described, with a detailed description of the correction strategy of systematic contributions to the measurement uncertainty of analog-to-digital converter conversion. An experimental evaluation of its metrological performances is made by means of several experimental tests, with both sinusoidal and distorted voltages and currents, which were carried out with an electric power standard and a high-performance multifunction calibrator

A DAQ-based sampling wattmeter for IEEE Std. 1459-2010 powers measurements. Uncertainty evaluation in nonsinusoidal conditions

“…After the correction, for both DAQs the offset and gain specifications were reduced and the values shown in Table 1 were obtained. The experimental comparisons presented in [31] showed the effectiveness of the correction. Obviously the approximation of the 50 Hz transfer characteristic to the static transfer characteristic was not rigorous (even more in the presence of harmonics); in [33] this was taken into account for the evaluation of the uncertainty of the instrument in sinusoidal conditions [33].…”

“…In [31] offset and gain correction was implemented by using the static transfer characteristic for both DAQs, which was obtained from a least squares method (with 40 points and 22 points for NI 9239 and NI 9225, respectively). A Fluke 5720A high performance multifunction calibrator was used as a reference [41].…”

“…In [31] the authors proposed a DAQ-based sampling wattmeter (DAQ-SW) for power measurements according to the IEEE Std. 1459-2010, to be used in the presence of both sinusoidal and non-sinusoidal voltage and current signals (frequencies up to 2.5 kHz were considered, i.e.…”

“…The comparison was carried out with sinusoidal signals and the obtained results confirmed that high accuracies can be reached also with such DAQsbased solutions. As regards the characterization in the presence of distorted voltages and currents, in [31,32] it was shown that the uncertainties of generated values of the Fluke 6100A/E power calibrator were high if compared to the error values (i.e. the differences between the values provided by the power calibrator and the values measured by the DAQ-SW) and the related standard deviations, which were obtained for active and reactive power.…”

Development, implementation and characterization of a DSP based data acquisition system with on-board processing

“…For example, they are used in power quality monitoring [10,11], in impedance measurement and spectroscopy devices [12], in the characterization of energy-harvesting devices [13], in environment monitoring [14], in real-time reflectometry diagnostic [15], in fusion experiments [16], in power metering [17] and many other applications.…”