Time-frequency transform-based differential scheme for microgrid protection

• Published in: IET generation, transmission & distribution Vol. 8; no. 2; pp. 310 - 320
• Main Authors: Kar, Susmita, Samantaray, Subhransu Rajan
• Format: Journal Article
• Language: English
• Published: Stevenage The Institution of Engineering and Technology 01.02.2014; Institution of Engineering and Technology; The Institution of Engineering & Technology
• Subjects: Applied sciences; Connection and protection apparatus; Contours; differential energy‐based protection scheme; Distributed generation; distributed power generation; Electrical engineering. Electrical power engineering; Electrical power engineering; Exact sciences and technology; fault current signal; fault currents; fault inception; fault pattern; Faults; grid connected mode; high‐impedance fault; islanded mode; loop structure; Mathematical analysis; microgrid protection; Miscellaneous; power generation faults; power generation protection; power generation reliability; power grids; Power networks and lines; power system interconnection; radial structure; Registers; shunt fault; Spectra; spectral energy content; S‐transform; Thresholds; time‐frequency analysis; time‐frequency contour; time‐frequency transform‐based differential scheme; Transforms; wavelet transforms; wide area protection; time-frequency transform-based differential scheme; wavelet transforms; fault currents; distributed power generation; fault current signal; power generation protection; fault pattern; wide area protection; time-frequency analysis; power system interconnection; time-frequency contour; power generation faults; grid connected mode; shunt fault; power grids; differential energy-based protection scheme; microgrid protection; high-impedance fault; power generation reliability; islanded mode; spectral energy content; fault inception; loop structure; radial structure; S-transform; Electrical network; Shunt; Spectral energy; Differential protection; Protective device; Grid-connected system; Distributed system; Differential method; Damage prevention; Distribution network; High impedance; Fault currents
• ISSN: 1751-8687; 1751-8695
• DOI: 10.1049/iet-gtd.2013.0180

The study presents a differential scheme for microgrid protection using time-frequency transform such as S-transform. Initially, the current at the respective buses are retrieved and processed through S-transform to generate time-frequency contours. Spectral energy content of the time-frequency contours of the fault current signals are calculated and differential energy is computed to register the fault patterns in the microgrid at grid-connected and islanded mode. The proposed scheme is tested for different shunt faults (symmetrical and unsymmetrical) and high-impedance faults in the microgrid with radial and loop structure. It is observed that a set threshold on the differential energy can issue the tripping signal for effective protection measure within four cycles from the fault inception. The results based on extensive study indicate that the differential energy-based protection scheme can reliably protect the microgrid against different fault situations and thus, is a potential candidate for wide area protection.