Novel protection scheme for EHV transmission line based on traveling wave energy

This article presents a novel protection scheme for extra high voltage (EHV) transmission line, aiming to address the problem of low reliability associated with the traditional protection methods relying on traveling wave or transient characteristics. When the fault traveling wave (TW) reaches the bus, a portion of the energy propagates to other lines through refraction, while the remaining energy is reflected back to the fault line. This phenomenon ensures the conservation of traveling wave energy at the bus. Within a specified time window, the incident TW is replaced with the reverse TW, and the reflected TW is replaced by the forward TW. This approach introduces a directional energy conservation property. The ratio of reverse TW energy to the combined energy of the forward TW and refracted TW was employed as a criterion to identify whether the fault is within the protection zone. PSCAD/EMTDC simulations show that this scheme can identify the internal faults and external faults quickly and reliably, which is not affected by the fault resistance, the sampling rates, the time windows, fault types, and have excellent adaptability to small fault inception angle. A practical case demonstrates the feasibility of the protection scheme proposed in this article.