Design Of A New Type Power Quality Meter Based On FPGA And Sigma-delta Data Acquisition Structure

Power quality measurement in power grids is an important part of power quality problems monitioring and governance.The accurate measurement to each power parameter provides strong data support for power system security management.Based on FPGA,magnetic balance principle of voltage transformer and sigma-delta data acquisition structure,this paper presents a new type power quality meter in view of the existing non isolated power quality metering tools.This meter can not only guarantee the equipment to be protected from the influence of the over-voltage fault,but also can monitor the power parameters of the power system in real time.Firstly,this paper designs a sigma-delta data acquisition module,which uses FPGA as the digital control core.Through over sampling technique and a digital decimation filter algorithm,this module implements the analog to digital conversion process of input voltage and current signals combined with the magnetic balance principle of voltage transformer.This module will not only isolate the power metering tool from the grids side,but also reduce the system costs by not using the AD conversion chip.Secondly,based on the research of power parameters calculation theory,this paper designs and chooses suitable algorithm to measure the signal frequency,voltage and current RMS,active power,reactive power and up to 21 times harmonic content.The reactive power measurement based on Hilbert transform and the measurement of each harmonic content based on FFT transform are narrated.With the help of the IP core of Altera company to complete the design,and the correctness of each function is verified by simulation.Finally,a hardware detection platform based on FPGA and ARM architecture is built,and the development of power measurement tool is completed.The division of labor in these two processors is clear,FPGA completes data acquisition and power parameters calculation,ARM controls the system communication and the results display.At last,this paper develops a precision measurement,real-time display,safe and reliable power quality metering equipment.