**Mustapha Errouha**

Mustapha Errouha received a bachelor's (BTech.) and master's degree (MTech.) in electrical engineering from Sidi Mohamed Ben Abdellah University. He received his Ph.D. Degree in electrical engineering and renewable energy from the Faculty of Sciences and Technologies, Sidi Mohamed Ben Abdellah University, in 2020. He was an assistant researcher at GREEN laboratory of the University of Lorraine, France. He is currently an assistant professor at the Engineering School of Toulouse, "Ecole Nationale Sup ´ erieure d'Electrotechnique, d'Electronique, d'Informatique, d'Hydraulique et ´ des Tel´ ecommunications" (ENSEEIHT). In 2021, he joined the "Laboratoire Plasma et Conversion ´ d'Energie" (LAPLACE), Toulouse, as a researcher. His research interests include motor drives, renewable energy, power electronics, smart grid, artificial intelligence, and embedded systems. He has published several papers in peer-reviewed journals and presented his work at various international conferences. He has served on the technical program committees of several international conferences, and he is a regular reviewer of top-tier scientific journals related to his field.

**Salima Abeid 1,\*, Yanting Hu 1, Feras Alasali <sup>2</sup> and Naser El-Naily <sup>3</sup>**


**Abstract:** The coordination of optimal overcurrent relays (OCRs) for modern power networks is nowadays one of the critical concerns due to the increase in the use of renewable energy sources. Modern grids connected to inverter-based distributed generations (IDGs) and synchronous distributed generations (SDGs) have a direct impact on fault currents and locations and then on the protection system. In this paper, a new optimal OCR coordination scheme has been developed based on the nonstandard time–current characteristics (NSTCC) approach. The proposed scheme can effectively minimize the impact of distributed generations (DGs) on OCR coordination by using two optimization techniques: genetic algorithm (GA) and hybrid gravitational search algorithm–sequential quadratic programming (GSA–SQP) algorithm. In addition, the proposed optimal OCR coordination scheme has successfully employed a new constraint reduction method for eliminating the considerable number of constraints in the coordination and tripping time formula by using only one variable dynamic coefficient. The proposed protection scheme has been applied in IEEE 9-bus and IEC MG systems as benchmark radial networks as well as IEEE 30-bus systems as meshed structures. The results of the proposed optimal OCR coordination scheme have been compared to standard and nonstandard characteristics reported in the literature. The results showed a significant improvement in terms of the protection system sensitivity and reliability by minimizing the operating time (OT) of OCRs and demonstrating the effectiveness of the proposed method throughout minimum and maximum fault modes.

**Keywords:** overcurrent relays; optimum coordination; microgrid; distributed generation; nonstandard time–current characteristics; tripping time
