Design And Verification Of Energy Measurement Module In Three-Phase Electric Meter

Electric energy is the main energy of the national economy and people’s lives.As a special instrument for measuring electric energy,electric meters are widely used in all aspects of power generation,transmission,distribution and electricity consumption.As the core of the meter,the energy measurement module’s hardware circuits and metering algorithms directly affect the accuracy of the meter,which has been an important topic for meter companies to research.This thesis primarily studies the electrical energy measurement module in the three-phase meter project of the internship company.The electrical energy measurement module primarily realizes the full-wave energy metering function and the synchronous sampling function.Firstly,this thesis introduces the theoretical calculation formula of electric parameters and the fast Fourier transform algorithm.Then the problems of spectrum aliasing,spectrum leakage and picket fence effect of FFT algorithm in harmonic detection are studied.And the characteristics of common window function and bispectral interpolation algorithm are analyzed.Secondly,in order to realize the full-wave energy metering function,this thesis designs a full-wave energy metering algorithm.Then this thesis introduces the design process,structure and characteristics of each digital filter in the full-wave energy metering algorithm,and uses MATLAB software to build a simulation model.MATLAB simulation shows that the reactive power measurement error of the algorithm is less than 0.03%,and the active power measurement error is less than 0.022%,which meets the design requirements.Thirdly,in order to realize the synchronous sampling function,this thesis proposes a synchronous sampling algorithm based on the sampling rate converter.The principle,structure and design process of frequency measurement circuit and sampling rate converter in the algorithm are introduced in detail,and the errors of the algorithm are analyzed.Then using MATLAB to build a simulation model,the simulation results show that the measurement error of each harmonic is less than 0.08%,which meets the design requirements.Finally,this thesis analyzes the length of the register under the finite word length effect,and uses Verilog HDL to implement the full-wave energy metering algorithm and the synchronous sampling algorithm.Then the author uses VCS software to simulate the design and verify the correctness of the function,uses DC synthesis tool to synthesize the design,uses the XC3S2000 FPGA chip of Xilinx’s Spartan3 series to build a verification platform to verify the correctness of the design.The measurement results show that the active power measurement error is less than 0.032%,the reactive power measurement error is less than 0.04%,and the FFT result error after synchronous sampling is less than 0.2%,which ensures the consistency between the algorithm and the design,and satisfies the design requirements.