Research On Instrument For Measurement Of Voltage Flicker

Voltage flicker is one of the most important indexs to assess power quality. With the widely used of electrical equipment with the impactive load and non-linear load, voltage flicker caused more and more serious harm. It caused damage to electrical equipment, affected the safe operation of power grid, maked a serious impact on power quality.This paper analyzes of the voltage flicker demodulation methods detailed. Based on the basic principle of several voltage flicker demodulation methods, such as the square demodulation method, full-wave recetifier demodulation method, the RMS demodulation method, wavelet transform demodulation method, Hilbert transform demodulation method, the voltage flicker demodulation method based on energy operator is proposed, and the discretization formula of the method of the voltage flicker demodulation based on energy operator is derived. It is vertified that the energy operator algorithm is applied to voltage flicker measurement feasibility not only with the singel-frequency amplitude flicker signal but also with the multi-frequency amplitude flicker signal by the simulation software of MATLAB.The simulation analysis is proved that the voltage flicker method based on energy operator is accurate and reasonably by comparing with the detection results of square demodulation method and Hilbert transform demodulation method. The method to calculate the flicker severity used by the IEC recommended flicker meter is introduced and simulated in the simulink simulation. In order to get voltage flicker index accurately, based on the analysis of the method to calculate the flcker severity used by the IEC recommended flicker meter, a method based on FFT to calculate the flicker severity is advanced, and the calculating steps of the method is given.Simulation results concluded that the method based on FFT is more simple and convenient by compared with the method used by the IEC recommended flicker meter.Based on the analysis of voltage flicker demodulation method and the method to calculate the flicker severity, a instrument for measurement of voltage flicker with a human machine interface and network communication functions. It can measure basic electrical parameters and voltage flicker parameters, immediately test and store the failure envent. The hardware system of this instrument used TMS320F2812 from TI as the core, and the each hardware component of the system is described in detail. We apply modular program design method to the design of the software of each module in the system.Finally through the experimental test, we verify the feasibility of the voltage flicker measurement method and the flicker value calculation method applied in this paper.