Research On Voltage Fluctuation And Flicker Measurement Algorithm And Analysis Method

In recent years, with the increasing of nonlinear、volatility and impact load in the powersystem, the voltage fluctuation and flicker problems become more and more serious, causeselectrical equipment damage and the user production loss. In this thesis, the parameterdetection method and disturbance source location method on the voltage fluctuation andflicker are discussed, providing the basis for the management of the power quality problems.First, the reason and harm of the voltage fluctuation and flicker are introduced, thecommonly used method of voltage fluctuation and flicker detection are summarized; Threekey links, the flicker measurement fluctuating signals extraction, instantaneous flicker valueacquisition, and short-term flicker value realization method of calculation are researched, thesynchronous detection method, the effective value detection method and rectifier detectionmethod’s characteristics on signal extraction are analyzed; Develop the IEC detector model byMATLAB/SIMLINK, and use this model to verify the accuracy of other algorithms.Then, this thesis proposes a fast Fourier transform (FFT) voltage flicker correctionalgorithm. The flicker detection method based on fast Fourier transform (FFT) is muchsimpler than the IEC method, and has been widely used in flicker measuring instrument, butexist measurement error. Using the single-frequency modulation wave and double-frequencyone for flicker detection input signal, this paper compared each processing step between theFFT-based method and the IEC method, found out the error of the FFT-based method, andthen proposed correction method. The correction method was also applied to flickerestimation containing three-frequency modulation wave. The simulations results show that theflicker estimating results by the modified FFT-based method are consistent with the IECmethod, and meet the requirements of IEC standard.Finally, this thesis studied the positioning method of flicker source. The commonlyflicker source location method, such as voltage current correlation method and flicker powermethod’s characteristic are analyzed. Voltage current correlation method is simulated. UsingPSIM as a simulation tool, the nonlinear resistor as the flicker source, by comparing thepublic join point’s voltage waveform correlation to current of each branch to determine theflicker source, the correctness of the flicker detection method is verified.