Design And Implementation Of Software For High Precision Power Analyzer

With the development of the power electronics,the measurement of power indices is becoming more and more important.Ordinary power meter is difficult to meet the needs of measurement with high accuracy,which under the conditions of voltage distortion,current distortion,unbalanced supply and other occasions.Multiple instruments can accomplish the testing task together,but the testing system is complex and difficult to build.It is necessary to use a multi-channel high precision power analyzer to measure all the key power parameters,and it can analyze high order harmonic,measure various power parameters with high accuracy,display real-time waveform of voltage and current.High precision power analyzer has wide application and high value of research,while there is a big distance between domestic high-precision power analyzer and foreign high-end products.Firstly,the overall software scheme of high precision power analyzer is designed,and OMAP-L138 dual-core chip is selected as the main control chip in this project.The DSP program is responsible for the calibration and parameter calculation of data,which is sent by the FPGA.The ARM program is responsible for the design and implementation of the human-computer interaction.Calibration of sampling data is a method to achieve high measuring accuracy of voltage and current.In this paper,a nonlinear algorithm of calibration based on sinusoidal excitation and DFT is adopted.Combined with the actual situation of the project,the interval of calibration is designed.When the interval of calibration is one period,compared with half period,the simulative result shows that the error of calibration is reduced from?6?10^-4 to?1?10^-4,while the input has stochastic white noises with 5%amplitude?26dB?.For the measurement of harmonic,Cooley-Tukey algorithm is adopted because of radix-2 FFT algorithm is limited by the number of sampling points,which can calculate the harmonic content of each order accurately after simulation.For the measurement of power parameters,based on IEC standard,the measuring methods of calculation is determined under different mode of connection.After realizing the interaction of data and management of events,the human-computer interaction of prototype can not only display waveforms in real time,but also display power parameters in a variety of ways.Finally,a complete high-precision power analyzer is tested on the actual platform.The testing results show that all functions of measurement are working normally;By using the algorithm of calibration,the measuring accuracy of voltage and current is improved from 0.088%to 0.04%.The measuring accuracy of frequency,reactive power and harmonic also meet the requirements.