Accurate protection current transformer parameters determination method under high noise immunity

Protection current transformers (CTs) should be tested both before installation and during a maintenance program to assure their correct operation. Realizing the existence of a high number of installed CTs in an interconnected power grid would make this procedure costly and time consuming. This paper describes how to develop an economic, accurate, and time-efficient microprocessor-based CT test set. A full-bridge inverter is utilized to generate a novel time-efficient voltage signal to measure the required CT parameters. Using a fast discrete wavelet denoising algorithm empowers the test set to be used for actual on-site application where the measured signals are highly contaminated with the plant noise. The validity of the proposed method is verified against a wide range of real experimental results. The results emphasize that the method is effective, reliable, and accurate.