A PC-based three-phase system analyser

Abstract

As the use of power electronics and inductive loads on electrical supplies increases, the requirement to monitor power system quality becomes an increasingly common practice. The negative effects these loads have on supply balance and frequency can be reflected in the efficiency, and therefore the running costs, of said loads. With demand for analysis techniques in industry increasing, and the PC becoming a more popular tool for such applications, a low-cost PC-based electrical system analyser was proposed to demonstrate a cost-effective, accurate alternative to the expensive market-leading products. This study researches the problem at hand, the technology available, and the development and testing of the analyser in a laboratory environment. The success of this study was determined by the accuracy, cost, functionality and features of the analyser compared with those of an existing product. The final product was to be a virtual instrument (VI) PC application implemented using the industry-leading LabVIEW software package by National Instruments. Two major challenges of the study were the correct measurement of the fundamental voltage and current waveforms, and the appropriate/accurate reconstruction, manipulation and display of these signals within the software. Identification, and minimisation or correction, of measurement errors was an important factor in achieving maximum accuracy prior to software interpretation of the data. Testing and calibration were carried out with the aim of providing the most accurate signal measurement prior to data acquisition and rescaling by the software program. Industry-standard design and manufacture techniques were implemented to produce a high-quality hardware package featuring a printed circuit board, ingress protection (IP) rated enclosure and screened multicore signal cabling. The potential uses and benefits of the analyser include monitoring loads in factory floor or manufacturing environments where production costs are of significant importance; in this instance, multiple analysers could be in place over the floor to aid operators. Smaller companies using smaller amounts of large machinery may implement a PC-based system as a cheaper alternative to an expensive all-in-one unit. The study concluded that a reasonably accurate PC-based analyser could be produced on a small budget; it also highlighted the many advantages of a PC-based system in terms of usability, customisation and flexibility. A critical evaluation of the system’s performance compared to a benchmark model and further suggestions for improvement are included.