New smart multi-ended differential: Solution for power networks

Current differential protection works based on the Kirchhoff's current law. The old technique analyse the vector sum of the measured currents and detect faults in the protected area, but for that, we need to rely in an asymmetrical sampling using a ping-pong delay measurement technique or an external equipment to provide a time source referenced (e.g., GPS-synchronized). The new smart Multi-Ended Differential Protection presented in this paper uses new techniques to solve the problems presented previously, and includes a New CT Saturation Technique, a New Capacitive Current Compensation, and a New Multi-Ended Fault Locator, which make the IED scalable for any topology of the transmission system including Hybrid Lines. Based on samples, that makes the protection immune to frequency variations, is a Subcycle tripping Differential with a typically tripping time of 7ms, including 2ms of propagation delay between ends. Generic technique for differential protection immune to CT saturation without CT saturation detection, determine the internal and external fault based on samples. The correction of the distorted signature is using average and DC offset filters and a correlation technique is employed for phase comparison. As result of those new elements in differential function, a decreasing up to 2 times on CT requirements is achieved. Using a more accurate algorithm for Capacitance Current Compensation with distributed parameter line model, where only the impedance and admittance per unit are required, and this technique has an error less than 1% even considering transients in the algorithm. The Multi-Ended Protection has also a scalable algorithm for multi-ended fault location for any number of terminals or junctions in your power line system. Based on both voltage and currents is immune to DC offsets that make the function more accurate, less than 2%. The need to provide new equipment's with different requirements and constraints has pushed for the development of new transport networks. This new smart concept will be a step forward towards utilities moving to a reliable, cost effective and integrated protection relay to be implemented in any power networks.