This paper summarizes different efforts to overcome the modern challenges of over-current protection coordination in distribution systems. A brief background is introduced from a general perspective and then specifically describing in detail the problem of equipment coordination with a thorough link among mathematical concepts and fundamentals in practice. The operation challenges and ideas to avoid incorrect performance are discussed. Finally, the research proposes a new optimization method based on the combination of firefly algorithm and target remedy to overcome such challenges. The method is described and validated in the IEEE 242.2001 to meet existing regulation of protection coordination. Further research is expected to assess the performance of the proposed method under different fault scenarios with complex coordination of time current curves.