Research On Energy Metering Technology Under The Influence Of Voltage Fluctuation And Flicker

As the signal distortion of the power grid becomes increasingly serious,the problem of electric energy measurement in the case of distortion has attracted widespread attention from experts and scholars.How to measure electric energy accurately on condition of distortion has become an urgent problem to be solved in the field of electric energy measurement.In the modern power system,there are many reasons for the waveform distortion of the power grid.Voltage fluctuation and flicker not only cause the signal waveform of the power grid to be distorted seriously,but also cause measurement errors or even equipment failures of the power meter.Nonlinear loads and impact load are increasing rapidly,voltage fluctuation and flicker of grid signal are becoming gradually serious.It have seriously affected the accuracy of the electric energy measurement,which caused electric energy measurement devices to suffer from the problems of power loss,miscalculation.Meanwhile,it also caused serious harm to industrial production and social life.The research background and significance of this thesis is proposed and the current research status of the existing electric energy measurement technology under steady state and non-steady state conditions is analyzed.It is pointed out that existing electric energy measurement devices and the methods of electric energy measurement cannot accurately measure under the influence of voltage fluctuation and flicker.In order to study the problem of electric energy measurement under the influence of voltage fluctuation and flicker.The measurement error law of inductive power meter and electronic power meter under the influence of voltage fluctuation and flicker is studied at first to establish the error model of the two.Then,the limitation of the full energy metering method and the fundamental energy metering method is discussed,and the applicability of the existing electric energy measurement standard IEEE Std 1459-2010 is researched.The voltage and current signal models under the influence of voltage fluctuation and flicker are constructed,which is to realize measurement of electric energy accurately.The power mathematical model is deduced and simplified under the circumstances of voltage fluctuation and flicker.It is verified the accuracy and rationality of the simplified model through simulation.At the same time,the theory of time-frequency analysis of wavelet packet transform is deeply studied,and a new method of electric energy measurement under the influence of voltage fluctuation and flicker is proposed based on wavelet packet transform.In order to verify the accuracy and rationality of the algorithm in this thesis,the wavelet packet algorithm is deeply studied,and wavelet basis function that is suitable for voltage fluctuation and flicker measurement is selected.And a large number of simulation experiments on the energy measurement method proposed in this thesis are carried out by using MATLAB tool.The active energy metering under the influence of voltage fluctuation and flicker is also simulated.In addition,the effect of voltage fluctuations and flicker signals on energy metering under steady state and non-steady state conditions is studied.The simulation results show that the power measurement method based on wavelet packet transform proposed in this paper can effectively separate the fundamental wave component and the distortion component of the grid signal,and can accurately and effectively realize the accurate measurement of energy under the influence of voltage flicker.A new electric energy measurement devices based on a new ADC+DSP+ARM architecture is established.The hardware circuit designs of the data acquisition unit with the core of ADS1278,the data processing unit with the core of TMS320C6745,and the management unit with the core of K60 are completed.Based on the error of the novel electric energy measurement devices under the influence of voltage fluctuations and flicker caused by wavelet packet transform.The methods of the ratio and angle difference correction under the influence of voltage fluctuation and flicker are proposed.