Synchronization-Based Differential Protection for CT Saturation in Marine Systems with Validation

In marine electrical systems, differential protection is essential for safeguarding electrical equipment from internal faults. However, current transformer (CT) saturation can cause false operations, especially under high fault currents. This paper introduces a Synchronization-Based Differential Protection (SBDP) method to improve reliability. The method uses the 4–5 millisecond delay before CT saturation, utilizing transient changes in current and voltage as operating signals to ensure fault response while the CT is in its linear region. Upon detecting transient signals, the differential protection relay is opened for 3–4 milliseconds to check for differential signals. If detected, protection is triggered; if not, it is locked to prevent false trips due to CT saturation. Theoretical analysis and practical validation show that this method effectively reduces false operations caused by CT saturation, enhancing the differential protection system's accuracy and reliability. This provides an effective solution for CT saturation in marine electrical systems, ensuring stability under extreme fault conditions.