In order to study the noise problem that affects the measurement accuracy of fiber optic current transformers, a noise analysis method based on Allan variance is proposed. Through calculation and analysis of measured signals, a random error model of fiber-optic current transformers containing 5 noise items is established. The least squares method is used to calculate the noise figure of each noise item, and the noise characteristic is analyzed. The signal noise of the optical current transformer is processed by the wavelet transform soft threshold method. The research results show that the noise analysis method based on Allan variance can effectively identify the noise sources of fiber-optic current transformers, and the noise coefficient can be fitted to quantify the size of each noise error by the least squares method. The use of wavelet transform soft threshold filtering method can effectively filter the signal noise of the fiber optic current transformer.

Allan variance,fiber optical current transformer,Least squares method,noise figure,wavelet transform soft threshold method