Novel Transmission-Line Pilot Protection Based on Frequency-Domain Model Recognition

Accurate frequency components of fault transient signals can be analyzed by the Matrix Pencil algorithm. By means of the Matrix Pencil algorithm, a new pilot protection principle for transmission lines based on frequency-domain model recognition is presented in this paper. First, the frequency-domain models at the internal and external state are built. Then, two model errors are defined for the two models to distinguish internal faults from external faults since the characteristics of the two frequency-domain models are opposite. For an internal fault, the fault data satisfy the internal fault model, and the internal fault-based model error is equal to zero. While for an external fault, the fault data satisfy the external fault model, and the external fault-based model error is equal to zero. Thus, the fault can be distinguished easily by model recognition. Besides the fundamental frequency component, an aperiodic component and other frequency components extracted by the Matrix Pencil algorithm are also applied in the protection to make the principle suitable in fault steady and fault transient state. Eventually, data from both Electromagnetic Transients Program simulation and dynamic physical simulation demonstrate that the novel pilot principle can detect the internal fault quickly and reliably, immune to the impacts of capacitive current and transition resistances.