*1.3. Contribution of The Paper*

It can be seen that there are some drawbacks or imperfect points that create a research gap. There is a significant need to find an alternative to the NI standard curve for more flexible and dynamic protection coordination schemes for radial and ring distribution networks (DNs) and MGs, especially at far-end faults (minimum faults). In addition, ensuring the CTI selectivity between OCRs and minimizing the tripping time in different operating modes are required. For filling this discussed research gap, optimal OCR coordination based on a new nonstandard time–current characteristic (NSTCC) with dynamic coefficients to provide a fast and reliable response in different network scenarios is proposed. An optimization task to present the OCR coordination problem has been solved by applying two optimization techniques, namely GA and GSA–SQP algorithms. The main and key contributions of this article are ordered as follows:

