An optimization method of harmonic analysis in IEC framework

FFT is a commonly used method of harmonic analysis in power system. IEC61000-4-7-2002 recommends using the FFT method with rectangular window for synchronous sampling data, and Hanning window for non-synchronous sampling data. Currently, most of the power wave recording equipment are sampling at fixed frequency, which is a nonsynchronous sampling method. Large error will be caused when directly using the FFT. This paper propose the method to synchronization the data using the interpolation method on non - synchronous data in time-domain and then using recommend method processing synchronous re-sampling data recommend by IEC61000-4-7-2002 to calculate the magnitude of harmonics and inter-harmonics. This algorithm is developed on C# platform and the results were compared with the result using the IEC recommended method for non-synchronous data, which proved the effectiveness of the algorithm.