Combined wavelet transform and regression technique for secondary current compensation of current transformers

A technique is proposed to effectively and efficiently compensate for secondary current of current transformers, particularly in the presence of remanent flux. The technique first utilises the wavelet transform to accurately distinguish the distorted section from the healthy section of a secondary current waveform. Secondly the technique uses the regression method to recover the distorted section making use of features extracted from the healthy section, essentially to restore the secondary current to a scaled down replica of the primary system current. The proposed technique is demonstrated on a sample power system, achieving an average compensation error of 1.5% under varying degrees of saturation caused by different levels of remanent flux.