Predictive Analytic to Supervise Zone 1 of Distance Relay Using Synchrophasors

• Published in: IEEE transactions on power delivery Vol. 31; no. 4; pp. 1844 - 1854
• Main Authors: Lavand, Swati A., Soman, S. A.
• Format: Journal Article
• Language: English
• Published: New York IEEE 01.08.2016; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Distance relay; phasor measurement unit (PMU); Phasor measurement units; power-swing blocking; Proposals; Protective relaying; Security; Transient analysis
• ISSN: 0885-8977; 1937-4208
• DOI: 10.1109/TPWRD.2016.2521784

Distance relays are the workhorses of transmissi-online protection systems. But those close to the electrical center will pickup even during transient instability. To identify them, we introduce a new coordinate system with normalized minimum magnitude of positive-sequence voltage on the line (V(min pu )) as the y-coordinate and angular separation of positive-sequence voltage phasors at line terminals (δ SR ) as the x-coordinate. We show that in the δ SR - V(min pu ) plane, the electrical center has a strong separation from a three-phase fault and stable disturbances. Subsequently, we propose a combined out-of-step prediction and relay blocking scheme. It uses line-end phasor measurement unit inputs for detecting vulnerable relays and blocking their zone 1 trip for a limited time interval before ingression into zone 1. We also show that it is possible to detect a line fault during the block state and consequently rescind the block decision. Extension of the proposed scheme to zone 2 and zone 3 is also described. Simulations considering noisy data and round robin delays demonstrate efficacy of the proposal.