The Electric Parameters Measurement Instrument Based On Virtual Instrument

Electric parameter is an important support for the automatic monitoring, control and protection of the power systems. The prompt and accurate measurement of electric parameters is of great significance for realizing the automation of the power network dispatch as well as assuring the safe and economical operation of the power network. The increasingly severe pollution of the electric environment, due to the increase of the proportion of non-linear, fluctuant and unbalanced load in the power system, has caused wave distortion and noise, which may greatly affect the precision of electric parameters' measurement. Meanwhile, the presentation of the power quality problem has further broadened the scope and intension of electric parameters' measurement while improving higher requirements on the measurement of electric parameters. The research of this thesis is carried out under the former background.This thesis, based on the technical characteristics of virtual instrument and electric parameter testing, puts forward a digital algorithm for the electric signals by DFT spectrum correction. The algorithm is suit for measurement of various electric parameters, and makes the best of the advantages of software by simplifying the procedure's structure. Simulation on the LabVIEW software development platform shows that this algorithm features itself in low calculating volume, quick response, high accuracy and stability in the final results.This thesis also probes into the detailed technical rules of 'Common Format for Transient Data Exchange for Power Systems' (COMTRADE), and then goes further into the design of a system of analyzing and reproducing the fault wave record. This system may convert the files of wave record into files in accordance with the standard COMTRADE format.The thesis combines the technology of virtual instrument with the algorithm of measurement of electric parameters and proposes a project plan of the hardware and software for the testing instrument aiming to meet the specific requirements of performance of the electric parameter testing instrument. A portable electric parameter testing instrument, which is multifunctional, easy to handle, convenient to maintain and upgrade and enjoys high performance-price ratio, is also developed on the LabVIEW platform through the application of USB date collection module. This instrument has undergone the inspection by the Hunan Electric Power Experimentation Institute successfully. The result of the inspection proves that the precision of the measurement of the instrument satisfies with the relevant national standards and the measurement requirements of the power systems' electric parameters as well.