# The Power System and Microgrid Protection--A Review
## 5 Conclusions  
This paper presented an overview of protection in power systems and microgrids. Protection systems need to be reviewed to consider the integration of distributed generation technologies. The presence of a microgrid causes many challenges in the protection of the power system. This study addressed these challenges and their solutions. Changing the protective relay settings and the optimal replacement of reclosers have been proposed to improve the performance of OC relays in blinding zones. The DOC relays have been used to avoid false tripping in the presence of DGs. Distributed energy resources should be isolated from the grid with fault. Furthermore, during the \begin{table}
\begin{tabular}{c c c} \hline \hline
**Characteristics** & **Traditional Power Grid** & **Smart Grid** \\ \hline Topology & Mainly radial & Network \\ Generation & Centralized (due to the & distributed (due to the private view) \\ Efficiency & Low efficiency & Relatively high efficiency \\ Control & Limited & More extensive \\ Reliability & Based on static, offline models & Real-time predictions \\ Distribution & One-way distribution & Two-way distribution From \\  & & alternative energy \\ Monitoring & Manual (due to the lack of sensors) & Self-monitoring using \\  & & digital technology \\ Response to Disturbances & Response after faults to prevent & Responds to faults by focusing \\  & further damage & on prediction \\ Technology & Electromechanical infrastructure & Digital infrastructure and \\ Restoration & Manual (due to the lack of controller) & Communication \\ Assets Management & Low data relationship with & Self-healing \\ Equipment & Failure and blackout & Planning for an asset with extensive \\ Customer Choices & Fewer choices & monitoring of their information \\ Active Participation Consumer & Consumers do not participate & Adaptive and islanding \\ Provision of Power Quality & Slow response to power quality & Consumers participate actively \\ Resiliency against Cyber-Attack and & Vulnerability to natural and human & Rapid resolution of power quality \\ Natural Disasters & destructive actions & Rapid resilience to cyber-attack and \\ New Products, Services, and Markets & Limited opportunity and the market & Integrated market and the right to \\  & for consumers & choose for customers \\ Reaction Time & Slow reaction time & Extremely quick reaction time \\ System Communications & Limited to power companies & Expanded and real-time \\ Sensors & Few sensors & Multiple sensors throughout \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Comparison of traditional power grids and smart grids. islanding operation of a microgrid, the protection and control are complicated. The presence of the microgrid also affects the recloser/fuse and the short circuit level. In addition, many protection schemes have been proposed to protect the power system against changing the topology in the presence of a microgrid. Various types of protection schemes have been considered to detect faults in microgrids, especially in an inverter-based microgrid in islanded mode. Most studies on microgrid protection in islanded mode were communication-based. Wide-area protection based on measurements obtained from PMU and intelligent protection systems can resolve many issues related to the protection and control of the smart grids in the future. In future protection systems, the wide-area protection can protect the power system with microgrids in proper time, including the time of collecting data, processing, analyzing, and tripping commands during the fault. Future works for completing this review may discuss various parts of adaptive protection schemes, such as digital relays, communication capabilities, and supervisory software. Moreover, discussing PMUs and communication platforms as well as implementing them in the control and protection of microgrids, especially in islanded mode, might be a hot topic.