Research On Power Quality Detection Method Of Voltage Fluctuation And Flicker In Digital Substation

Voltage fluctuation and flicker of electric energy quality is important as long as one of them. In order to adapt to the digital substation construction and advanced measurement system needs, and improve power quality detection, sync and test signals of digital substation voltage fluctuation and flicker detection method was studied.Firstly, introduces the power quality monitoring processes, development of digital substation, voltage fluctuations and flicker detection status, defined the importance of voltage fluctuation and flicker detection of digital substation. Introduces the concept of voltage fluctuation and flicker, and harm, and flicker test methods IEC advance, introducing statistical methods depending on the sensitivity of transient flicker flicker worthy statistics. Describes the characteristics and difficulties of digital substation, digitalized substation is different from traditional transformer substations, introduces the digital substation data acquisition structure, test data is different from traditional transformer substations, and synchronization of digital substation, clock synchronization and synchronization with the test data.Secondly, aiming at a wide range of voltage fluctuation signal detection, envelope detection method was introduced, the whole principle of voltage fluctuation and flicker detection, detection models, comparing the existing fluctuation signal detection method, Analysis square detection method, detection method, full-wave rectification method, Hilbert transform and Teager energy operator, Prony analysis methods as well as Pisarenko harmonic analysis, frequency and spectral estimation of noise subspace, and describes the advantages and disadvantages of each method. Filters are the basis of voltage fluctuation and flicker detection to detect an important part, describes the filter design, and had a small range of optimization and improvement. And that digital with pass filter bands number upgrade to six bands, filtering range extended to0.05-45Hz, will as frequency backward moved, settlement has due to six bands Butterworth low pass filter site frequency characteristics of transition with had narrow, attenuation rate had fast, caused instantaneous Flash changed depending on sense degrees not accurate of problem, and looked at each other sense degrees output curve for frequency transition coefficient correction, through simulation validation has its method of effectiveness.Thirdly, test signals needed for digital substation synchronization issues, presents a heterogeneous signal synchronization method based on maximum similarity principle, test signal synchronized with the standard, which can be used for detection of voltage fluctuation and flicker. For calculation of complicated envelope detection process, the Hilbert-Huang transform and mixed base DFT method improvement of combined detection method, you can reduce the computational steps, improving the computational efficiency, without affecting the accuracy of calculation. By optimizing the band-pass and order of digital filter sets parameters, an expansion of passband to band-pass filter. The promotion adds correction factor of turning frequency to the visual sensitivity weighting filter, and hoists optimization of a smoothed average filter order voltage flicker.