Design and challenges of current sensing and harmonic extraction for active power filtering for an industrial drive in oil and gas industry

The shunt active filters are highly effective in filtering the current harmonics originated from the nonlinear loads. The performance of the active filters depends very much on the accurate sensing of the voltage and current signals. Even though high performance active filters are proven in the literature, these require high bandwidth hall sensor current transformers (CT). These hall sensor CTs are not suitable for high power systems. This paper explores the options of using the existing conventional current sensors in the industrial systems. The data acquisition circuit is designed for three different types of current sensors. The harmonic current and fundamental components are extracted from these signals. The problems and limitation of the conventional CTs are studied and compared with the CTs based on Rogowski coil and hall sensor CTs. The suitability of these signals for active filtering is verified experimentally.