Harmonics Measurement with a Modulated Sliding DFT Algorithm

ORALLO, C.; CARUGATI, I.; MAESTRI, S.; DONATO, P. G.; CARRICA, D.; BENEDETTI, M.

IEEE TRANSACTIONS ON INSTRUMENTATION AND MEASUREMENT

IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC

Lugar: New York; Año: 2014 vol. 63 p. 781 - 793

0018-9456

Accurate harmonics estimation has become a key issue in power quality assessment. This paper deals with a DFT-(Discrete Fourier Transform) based measurement technique, which can be easily employed to accurately determine the harmonic components of a distorted signal, i.e., voltage or current. The proposed method is based on a mSDFT (Modulated Sliding DFT) algorithm, which is unconditionally stable and does not accumulate errors due to finite precision representation, and a Variable Sampling Period Technique (VSPT) to achieve a frequency adaptive mechanism. It is worth noting that the VSPT changes the sampling period for a variable grid frequency condition, leading to a constant sampling frequency under steady-state conditions. The proposed method provides (i) high degree of accuracy, (ii) structural/performance robustness, and (iii) frequency adaptability. Given the modular nature of the method, it is implemented on a Field Programmable Gate Array (FPGA). Simulations and experimental tests are shown to verify the performance of the proposed method