In order to eliminate the transient current and ensure the test precision, this paper introduces the principle and the method of phase selection of the AC based on FFT(Fast Fourier Transform Algorithm) .

• 为了消除暂态电流，本文阐述了一种基于快速傅立叶变换(FFT)的交流选相合闸技术的原理以及实现方法，保证了检测精度。