Inter-harmonics/sub-harmonics analysis based on odd points interpolation correction

摘要

Inter-harmonics/sub-harmonics is a kind of harmonics that are not an integer of the fundamental frequency component. The inter-harmonics/sub-harmonics has serious impacts on the design of harmonics compensation equipments and serious damage to the power system as same as the integer harmonics. So it is important to measure them accurately. The Fast-Fourier-Transform (FFT) has been widespread used in electric power harmonic analysis. But the asynchronous sampling will make harmonic analysis incorrect by use this algorithm. This paper will introduce a new method which is presented to reduce the leakage while interpolating. According to the FFT results, the phase angles of adjacent lines of side lodes could be against by phase rotation adjustment. Then use interpolation method to work out the frequency, amplitude and phase. Then removal every component that has being worked out in 100Hz from original sample, one can get the dc voltage directly. At the end of this paper, the data from a wind power station are calculated on Matrix Laboratory (Matlab).The results prove this method has a desirable accuracy.