Phase angle-based fault detection and classification for protection of transmission lines

Fault detection in transmission network is conventionally done by distance relays. Generally, these relays maloperate during power swings, load encroachment, and High Impedance Faults (HIFs). A novel phase anglebased approach for fault detection and classification of transmission lines is proposed in this paper. Instantaneous Phase Angles (IPAs) of local ends voltage and current measurements are estimated. These, with Discrete Fourier transform (DFT), are used to calculate Derived Phase Mean Indices (DPMIs), and Phase Mean Indices (PMIs) of each phase voltage and current of the line. A Global Fault Detector (GFD) setting is proposed for the evaluated indices to detect and classify the fault. The proposed approach is tested on a hybrid test signal and the Western System Coordinating Co uncil (WSCC) 9 bus system in Real-Time Digital Simulator (RTDS) with different fault resistances, inception points and locations, including HIFs, power swings, topology changes, load and capacitor switching. The effects of the presence of noise, asymmetry, harmonics and phase unbalance in the test signals on the proposed method are also investigated. The results obtained from RTDS and a simulation based comparison of the proposed method with a previous method prove the efficacy of the proposed approach to detect and classify faults and also act as an inherent power swing blocker and de-blocker.