Nonpilot directional protection of a microgrid

• Published in: Journal of engineering (Stevenage, England) Vol. 2023; no. 12
• Main Authors: Mohammadhassani, Ardavan, Mehrizi‐Sani, Ali
• Format: Journal Article
• Language: English
• Published: London John Wiley & Sons, Inc 01-12-2023; Wiley
• Subjects: Communication; Contingency; Controllers; Current injection; Design; Distributed generation; Electricity distribution; fault diagnosis; Fault location; Faults; Inverters; Neural networks; Relay; Support vector machines; Wavelet transforms
• ISSN: 2051-3305; 2051-3305
• DOI: 10.1049/tje2.12334

Protection of an islanded inverter‐based microgrid is challenging because of variable and small fault current contribution of inverter‐based resources (IBR) and the absence of sequence currents. This paper proposes a fast and robust nonpilot directional protection scheme to address this challenge. This scheme relies on support vector machines (SVM) and the harmonic current injection capability of IBRs. Examining the harmonic currents measured by a relay during a fault shows that harmonic currents have similar magnitudes but different orientation under forward and reverse faults. Additionally, harmonic currents have similar orientation but different magnitudes under forward faults at different locations along the protected line. Using this, six SVMs are trained for each relay, given that there are three main types of faults (three‐phase‐to‐ground, line‐to‐line, and line‐to‐ground): three as directional elements and three as zone detection elements. A fault is detected and classified by the undervoltage element of a relay. Then, the measured harmonic currents are routed to the appropriate directionality and zone detection SVMs to facilitate proper relay coordination. The performance of the proposed method is evaluated on the CIGRE North American MV distribution benchmark system under various types of contingency scenarios using PSCAD/EMTDC software.
Protection of an inverter‐based microgrid is challenging due to the lower available fault current and the absence of sequence components. This paper proposes a nonpilot directional protection scheme for inverter‐based microgrids that uses support vector machines to implement fast and reliable protection coordination in case of microgrid faults.