Phase detection algorithm and precision analysis based on all phase FFT

In the phase measurement of three-phase electricity signal, the measurement accuracy based on traditional FFT algorithm is restricted by harmonic components. Even though it can be corrected by some spectrum correction algorithm, such as FFT+DFT spectrum continuous refining method, phase difference method and so on, these correction algorithms are based on FFT results. So the precision is very limited. Aiming at the deficiency of traditional phase measurement methods, this paper applies digital phase measurements based on the all phase FFT algorithm. This algorithm has the characteristic of initial phase invariability and can prevent the spectrum leakage effectively. Using all phase FFT algorithm can solve the problem of non-synchronous sampling frequency spectrum correction, and improve the phase measurement accuracy obviously. In addition, it can forecast the precision of phase, and greatly reduce the computation. All of these characteristics make it helpful to achieve the phase real-time measurement.