Measurement And Analysis Of Voltage Fluctuation And Flicker

Voltage fluctuation and flicker is one of the typical power quality problems. The other aspects of research on flicker are based on the accurate detection of voltage flicker.Flicker envelope extraction is the key of voltage flicker detection. This paper analyzed and compared the ability of flicker envelop tracking using the classical detection methods and Hilbert transform, Teager energy operator method, instantaneous reactive power theory method. These methods have advantages and disadvantages and application range, respectively. A novel envelope extraction method based on LMD was proposed in this paper. The simulation data and field data show the accuracy and effectiveness of the method. Besides the detection precision of LMD method is higher, especially in the scope of low frequencies of flicker. This method can extract envelope of flicker signal containing harmonic without using filters. It makes up for the disadvantage of square demodulation recommended by IEC. Finally, on the basis of accurate detection of flicker, the propagation of voltage flicker in the entire power network was studied. Therefore, this paper deduced a formula for calculating the instantaneous flicker sensation level by fundamental and interharmonic voltage. A method for calculating Pst in the network was introduced by analyzing the propagation of voltage interharmonic. So that the flicker levels at any bus of the network can be determined effectively in this method. The flicker contributions determination at the PCC can be studied on the basis of the propagation algorithm. Finally, an example simulation proved that this flicker propagation algorithm is validity and accuracy by PSCAD/EMTDC.