The Research Of High Accuracy Electric Network Harmonics Measure And Analysis System

Power system harmonics affect the normal operation of power equipment, so the accurate measurement of the power system is important to power system. The fundamental signal and the harmonic signal are measured separately to improve the measurement accuracy of harmonics. The main frequency trap circuit whose trap bandwidth is wide is designed and analysis detailed. A lot of simulation is made and the simulation results show: the designed trap circuit has good frequency characteristics and phase characteristics. The attenuation of fundamental signal is large. The filtering effect is good even when the fundamental is between 49 .5Hz~50.5Hz. The designed frequency Notch circuit is used when measuring the voltage and current signals, and the fundamental signal in the measured signal can be filtered and the content of harmonic signal became large. The precision of harmonic measurement is improved.The measurement method of grid fundamental frequency is studied. Because many frequency measurement methods have poorly anti-interference capability and the frequency measurement accuracy reduced when the signal has many low-frequency oscillation signal and harmonic signal, therefore the filter is designed based on the bell-shaped pulse function. The sampling data is filtered to filter out other signal except the fundamental. Simulation is made based on the designed filter. Simulation results show: the filtering capacity of this method is strong. The good fundamental signal is obtained ever when the sampling signal has many low-frequency oscillation signal and harmonic signal. The existing frequency measurement methods based on sample date band-pass filtering is used to measure frequency. This can be assured of high frequency measurement accuracy.The fundamental frequency is measured accurately and the synchronous sampling is guaranteed. The accuracy of Fourier analysis is improved and the accuracy of harmonic analysis is also improved.According to the characteristics of the power system harmonics and the development of processor, the harmonic measurement system is built using ARM Forward channel and the ARM control circuit is designed. The performance of harmonic measurement system, circuit diagram, hardware flow chart and software flow chart is given.