Research On New Technology Of Electric Energy Measurement Under Distortion Signal Condition

With the rapid development of power electronics technology,the wide application of high-voltage,large-capacity nonlinear equipment such as electric arc furnaces,rolling mills and electrified railways has caused severe distortion of power system signals,causing serious fluctuations in power grid signals.Sudden changes,the rationality and accuracy of energy metering are directly affected.Ene rgy metering equipment designed with sinusoidal or non-sinusoidal power theory will not be able to accurately and reasonably measure the electrical energy under distorted signal conditions.Therefore,how to accurately and accurately measure the electric e nergy under the condition of distortion signal has become an urgent problem to be solved in the field of electric energy measurement.The research background and significance of electric energy measurement under the condition of distortion signal is described in this thesis.And the existing measurement standards and measurement algorithms suitable for distortion signals is introduced.The basic structure of analog electronic energy meter and electronic energy meter is studied.The law of phase error of current transformer caused by magnetic saturation,which is caused by distortion signal,is qualitatively analyzed.The influence of harmonic signal in distorted signal on analog multiplier and digital multiplier is quantitatively analyzed,and the expression of power measurement error is obtained.The influence of the non-periodic signal in the distortion signal on the power of the post filter is quantitatively analyzed,and the expression of the energy metering error is obtained,which lays a foundation for the research and device design of the energy metering algorithm.According to the characteristics of the distorted signal,the power mathematical model under the condition of distorted signal is constructed,and the improved FFT based on the new optimization window and fast wavelet transform power algorithm is proposed.A power metering algorithm based on K-N mutual convolution window for three-line interpolation FFT is proposed for steady-state signals,and the accuracy of the algorithm is verified by steady-state signal simulation.A power measurement algorithm based on improved fast wavelet transform is proposed for the unsteady signal,and the accuracy of the algorithm is verified by the unsteady signal simulation.The working principle of single-phase half-wave rectification circuit,electric arc furnace and high-speed rail traction is deeply studied.The simulink model is built in each case,and the distorted voltage and current signals are generated.The distorted voltage and current signals are generated through MATLAB.The power is calculated by the improved FFT based on the new optimized window and fast wavelet transform power algorithm.The simulation results show that the improved FFT based on the new optimized window and fast wavelet transform distortion energy metering algorithm can accurately measure the power of the grid distortion signal.Based on the improved window optimization FFT and fast wavelet transform distortion energy measurement algorithm,the energy metering device of ADC+DSP+ARM structure is designed,and the hardware design circuit of signal acquisition module,data processing module and data management module is introduced in detail.And the software design of the main program of the device,the energy metering and the data transmission,and the human-computer interaction module of the touch screen are also designed accordingly.Finally,the actual test of the energy metering device was carried out to verify the accuracy and effectiveness of the proposed method.