Real-time interharmonics detection and measurement based on FFT algorithm

The modern power systems are supplying an increasing number of non-linear loads like: double conversion systems, arc furnaces, arc discharging, high power cycloconverter (CCV) etc. These loads are harmonics and interharmonics sources. Therefore, it is important to measure interharmonics accurately. The Fast Fourier Transform (FFT) is used for signal processing because of its computational efficiency. Most power quality meters and digital relays adopt FFT-Based algorithm to characterize harmonics of the measured signals. The International Electrotechnical Commission (IEC) standards on power quality have defined the terminology, limits and measurements guidelines for interharmonics. This paper shows effects on windowing in the interharmonics detection based on IEC technique. Simulations and experimental results based on the real-time platforms are discussed.