The Compensation of Current Transformer Saturation for Proper Protection Operation

The article describes practical approach for compensation of current transformer saturation in terms of proper relay protection operation. Proposed algorithm is based on industrial controller operation structure manufactured by Prosoft Systems with built-in Rogowsky coil as current sensors. Thus, based on features of Rogowski coil, initial data for this approach is not a second current, but its derivate. The basic idea is to identify discontinuity points in the collected data, where signal goes from saturated to unsaturated part and in the reverse direction, and apply the short window effective value calculation algorithm, to the segment of unsaturated current curve instead of the whole window Fourier transformation. The data for this study is collected during Hardware-in-the-loop (HIL) simulation on eMEAGASIM OPAL-RT complex with Doble F6350e amplifiers. The short window approach results in accuracy increasing in effective value calculation, which can further be used in protection and control algorithms without time delay.