Research On Power Quality Test System Based On Virtual Instrument

The traditional Power parameters measuring system mainly based on hardware is single-function and high-budget, so it is unsuitable gradually for complicated and multiparameter test. Recent years, with rapid progress of electronic technology and computer technology, new testing theory and method, new instrument structure is appearing. Function and application of measuring instruments has changed a lot. One marked characteristic is appearance and development of Virtual Instrument with the advantage of simple hardware structure, user-defined, powerful data processing and analysis function. Besides, Virtual Instrument can achieve the function of history data management and graphical representation.Therefore, by analyzing the status of powe quality testing set home and abroad, in connection with the problems being falled across during testing of power quality, a power quality testing system based on Virtual Instrument is studyed and exploited in this thesis. The testing system can measure power parameter, such as voltage, current, frequency, three-phase degree of unbalancedness, voltage hunting and harmonic. These parameters slao can be analyzed real-time and saved in LabVIEW SQL corresponding databases, against inquairation and reanalyzation. In term of instrumentation development, LabVIEW and 16bit high degree of accuracy data acqusiton named PCI-6220 are selected in this paper, both of them are manufactured by National Instrument. In arithmetic respect, wavelet transform with synchronous detection is proposed and used to analyze voltage hunting. It has been proved that this method can detect and analyze voltage hunting exactly.Firstly,basic conception and strueture development of Virtual Instrument are introduced generally,also development Platform LabVIEW and Programming languageare.In connection with study state of Virtual Instrument and powe quality testing, the necessity that makes Virtual Instrument technology apply to powe quality testing is exposited. Then, measurement principles and gross structure of the testing system also be introduced.Secondly, the design and testing of system are xpounded particularly. The content mainly contains three parts, hardware design, software relized and result test. In part of hardware design, presented the parameters and characteristic of the data acqusiton card selected, finished the design of signal condiction circuit. In software part, development platform LabVIEW and programming language are introdueed, discussed total software structure and flow of work, introduced four function modual in detail such as date acqusiton, power quality basic parameters testing, date analyzation and date storge.In the part of result testing, test the signal which need to measure, and performs analysis of results.This testing system has many characteristics, such as good expansibility, strong reusability, and it can dramatically improve the automation of power qualituy testing. For this reason, It will be a trend that using Virtual Instrument to studying, designing and testing in test area of power system.At last, the shortage and some aspects needed improving of the system are given. The outlook of future research is put forward, too.