The Power Quality Measurement Instrument Based On Virtual Instrument

With the development of science, technology and economy, power quality problems are concerned by both power supply enterprises and customers, and the detection of power quality parameters becomes more and more important. Combining the latest virtual instrument technique with power quality measurement, a power quality detecting system with richer function but less cost in hardware is developed in this paper.In order to get suitable algorithms which are accuracy, feasible, practical and convenient to be realized by virtual instrument, this paper firstly analyzes measuring algorithms of major power quality parameters, such as voltage, current, frequency, harmonics, flicker, unbalance factor etc. Then two algorithms, the one for basic power quality parameters measurement based on spectrum correction and the other one for flicker measurement based on FFT, are presented. Both of algorithms adopt asynchronous sampling, which can save hardware expenses and make the best of the advantages of software. The algorithms, as well as the factors that impacts the measuring accuracy, are analyzed and tested by the simulations on LabVIEW platform; at the same time, the feasibility of the algorithms on LabVIEW platform is verified.Based on the above study, a power quality measurement instrument is designed. The method of hardware type selection and design of software module is detailed. The instrument not only can realize real-time sampling of voltages and currents in power system, but also can calculate the power quality parameters with the presented algorithms. With friendly interface, the device has various functions such as data saving, analysis, report forms print etc. It is convenient to use, and has extensive promotion prospects too. Practical operation proves that its performance can meet the various needs of power quality measurement.