The Research And Application Of Flicker Measurement Algorithm Based On Improved K-value Energy Operator And Multispectral Improved CZT

Voltage flicker is one of the most serious power quality problems of power system.The safe operation of electrical equipment and the normal operation of electronic equipment are severely affected by flicker,causing light flashing to make people prone to fatigue,vision loss and distraction.With the development of new energy and power electronic equipment,various non-linear and impact load increasing,voltage flicker becomes more and more serious of power system.The research background and significance of voltage flicker measurement are expounded in this thesis.The basic concepts and flicker evaluation indexes of voltage fluctuation and flicker are introduced,and the voltage fluctuation and flicker detection methods and voltage flicker detector are introduced at home and abroad.Aiming at the extraction method of voltage flicker envelope,several commonly used methods of voltage flicker envelope extraction are analyzed and compared.In order to extract the voltage flicker envelope quickly and accurately,an improved k-value energy operator demodulation method is proposed on the basis of deeply studying the Teager energy operator.The method not only quickly and effectively overcomes the interference of noise,but also deduces the process of extracting the voltage flicker envelope by deducing the improved k-value energy operator,and the voltage flicker envelope amplitude correction factor Ci is established.The simulation results show that the improved k-value energy operator algorithm can effectively extract the flicker envelope signal of single modulation frequency and the flicker envelope signal with multiple modulation frequency in the presence of noise.In order to build a fast,on-line measurement method for voltage flicker parameters and follow the IEC recommended flicker detection principle,through the analysis of IEC flicker measurement method,the voltage flicker measurement process recommended in the IEC standard is simplified.With the voltage flicker envelope extraction method with the improved k-value energy operator,an algorithm based on the improved k-value energy operator and Rife-Vincent window multi-spectrum-lines improved Chirp-Z transform(CZT)is proposed to analyze the discrete flicker measurement method.Five-term one-order Rife-Vincent window is adopted to perform weighted correction on the results extracted with the improved k-value energy operator,then the corrected results are analyzed and corrected with multi-spectrum-lines improved CZT,and the applicated correction formulas for the amplitudes and frequencies extracted from the voltage flicker envelope are deduced.Finally,the instantaneous flicker sensitivity and flicker values are calculated.The simulation analysis show that this approach has the high accuracy of measurement and can effectively overcome the influencys of the harmonic&inter-harmonic,grid fundamental frequency fluctuation and white noise on flicker measurement results.To verify the real time and effectiveness of the proposed method with the improved k-value energy operator and multi-spectrum-lines improved CZT,a flicker online measurement platform based on synchronous ADC+high-speed DSP+high performance ARM is built.The data acquisition module with the core of ADS 1178,the data processing module with the core of TMS320C6745 and the data management module with the core of K60 are introduced in detail.Then the software flow of flicker measurement unit modules is presented.The voltage flicker online detect platform is built.The experiment results show that the proposed method can achieve the online and precise measurement of the voltage flicker envelope amplitude,frequency and flicker value,and meet the real time and accuracy of voltage flicker parameters in embedded system.