Current Transformer Saturation Compensator by Using Negative Voltage Feedback

Current Transformers (CTs) saturation leads to distortion of current waveform and operational malfunction of protection relays. This paper introduces a practical and simple method to prevent CTs saturation. The method uses a negative voltage feedback and applies it to CT secondary side. The injected voltage opposes the excitation voltage of CT in a manner that the magnetic flux of CT remains almost constant under saturation level for any faults. The method is categorized as a hardware solution, does not need to detect the CT saturation time and works either for digital or non-digital relays. The method is verified in a wide range of simulations and experimental results. The obtained results show that the method is reliable, effective, and accurate.