The Research Of Power System Harmonic Analysis Based On SRFFT Algorithm

Recently, along with the broad application of Power Electronics Technology, many non-linear loads are used continuously in power systems, which make harmonic content rising rapidly, voltage shape distorting badly and power quality descending. The harmonics bring huge harm to equipment's safe and reliable run. As the same time, these make a series of influence on traditional measure methods and common instrument in 50Hz.If all harmonic parameters are measured exactly, electro-equipments go into power systems effectively on base of satisfying power quality harmonic standard. So power systems harmonic analysis is a significant aspect of power systems research.Power system harmonic analysis was realized usually with fast Fourier Transform (FFT),but the method exits spectrum leakage, and can not analyse all harmonic parameters exactly, such as frequency, amplitude and phase, in particular has big phase error. The paper analyses the advantages and disadvantages of a large number of harmonic analysis methods and puts forward to a new algorithm in order to improve precision of FFT, which is plural list and interpolating windowed split-radix FFT(SRFFT).The simulating result shows that the algorithm can meet precision of harmonic parameters. Moreover a example makes know, it can calculate lesser even harmonics exactly. Especially it is more obvious to improve the pricision for calculating their phases.The paper designs a data gather circuit aimed at the require of power system harmonic measure . Industrial computer(PIII800EB) processes the fact sampling value, also with its LPT1 transmits fastly data to reduce the measure time , to improve velocity and anti-disturbance. The paper designs a more LPF and a numberical filter to eliminate the error, and a frequency tracing tache because system frequency fluctuatesceaselessly. This guarantes synchronization sampling. Moreover the result realizes Real-time power system hamonic analysis based on A/D conversion drivers, control programme and algorithm sub-programme.