Research About Frequency Conversion Measuring System Of Dielectric Loss Based On DSP

The dielectric loss measurement of electric equipnent is a test of high delicacywhich can tell insulation state effectively. On the basis of analysis and comparation of conventional and some morden dielectric loss measurementmethods, considering the interference of strong electric field of the power grid in local measurement, a frequency conversion measurement method of dielectric loss is presented.In local dielectric loss measurement, thestrong interference of the industrial power grid is a same-frequency interference comparative to the useful signalsThe frequency conversion measurement method is the ultimate methodto eliminate it.That is to say we can use a test voltage whose frequency is different to 50Hz,then the same frequency interference becomes different-freqquency interference which can be easily eliminated.Based on this theory,and combined with Fourier transform frequency spectrum analysis and curve fitting ,the formula and arithmetic of equivalent mainfrequency for the frequency conversion measurement are derived. As to hardware, the manufacture scheme of the minitype frequency conversion measurement system of dielectric loss is introduced. The controlling and processing center of the hardware system are TMS320LE2407 DSP and MSP430F149 SCM. The hardware of this system mainly includes variable frequency powe,rvoltage/current signal sampling LCD, switching output/input and communication etc. As to software, modularized C and assembler language programs are designd to realize data samplingprocessing(include FIR digital filter FFT and arithmetic of dielectric loss parameter),variable frequency power and display keyboard processing etc, which make the system have the functions of control,measuring,display,man-machine conversation and communication etc.Anti-interference problem is fully considered in the design, and the advantage of DSP in digital signal processing and controlling is taken full use of, which makes the whole measuring system has a simple structure, good anti-jamming performance and high measurement precision.