With the evolution of power electronics technologies, DC networks have been considered as promising distribution systems for future grids. This new concept of power systems comes with technical challenges in protection coordination, a result of the no natural current zero- crossing point and very low thermal capacity of semiconductors in power converters. In order to overcome this technological barrier, many researches have been conducted. This paper presents a summary of the state-of-the-art on protection coordination technologies in DC distribution systems considering whole DC protection procedure: fault detection, fault localization, fault isolation and backup protection. In addition, two different protection schemes for low-voltage DC (LVDC) shipboard power systems (SPS) which are commercially viable measures are described.