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Adaptive protection coordination which realizes using communication links is an efficient method to solve problems in microgrid protection coordination. An issue that can affect the efficiency of this method is uncertainty in communication links. In order to evaluate the effectiveness of uncertainty in communication links on adaptive protection and reliability of microgrids, a new Markov Chain Monte Carlo (MCMC) is proposed. In the proposed method, the probability of correct operation of circuit breakers (CBs) and communication links is not considered to be constant; it can vary according to the fault current flowing through CBs and the latency of communication links, respectively. The performance of the proposed method is tested on a sample microgrid equipped by central server and communication links. In order to assess the impact of uncertainty in communication links on the reliability of the microgrid, System Average Interruption Duration (SAIDI), Expected Energy Not Supplied (EENS), and Expected COST of Interruption (ECOST) indices are used. Results prove that the traditional protection coordination schemes have more effectiveness of the uncertainty in communication links compare to schemes which use global decisions.

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The uncertainty in connection status of distributed generation and network structure complicates the adjustment of the overcurrent relays in distributing network. With the increase in number of modes of operation, the investigation area faces limitations and becomes even pointless, making it almost impossible to reach a unified host of setting applicable for all possible modes. Yet, the conditional situations could be overlooked and the investigation could be objective-oriented once the differential protection is maintained and the faults are taken care of instantly. The differential protections must be installed with the minimum number and in the proper places so that the incompatible conditions would be eliminated. As such, a new approach based on additional methods with regard to the nature of differential protection and its impact on identifying incompatible conditions is recommended. The outcome of such approach is a set of candid lines for installing the differential protections and thus the convergence of protective coordination of overcurrent relays. This approach has been simulated for the ringed distributed active network and, as the outcome reveals, the recommended approach with the proper placement of differential protections along with the unified setting for all relays makes the constant protection coordination possible.

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The changes in configurations of distribution networks due to the outages of any upstream substations or distributed generations (DGs) is one of the essential challenges in the design of distribution systems. The changes in topologies of the network affect the protective schemes and might lead to coordination constraint violations in different operation modes and configurations. It is inevitable to appear some coordination constraint violation if only the base grid-connected operation mode and configuration is considered in the optimal protection settings. The adaptive protective schemes have several advantages compared to those using only one setting group, and their speed would be more desired. Although different research works have been done in the literature in adaptive protective schemes, there is a research gap about considering the limited number of setting groups for directional overcurrent relays (DOCRs), besides other aspects of active distribution networks and adaptive schemes. This research tries to fill such a research gap by proposing a new optimized adaptive protection system, considering various network configurations, by the limited number of setting groups. Since the proposed optimal settings for DOCRs are applied to a limited number of setting groups, it would be practical. Optimizing the standard relay characteristics in the proposed method is another contribution. Test results of applying the introduced method on the distribution portion of the IEEE 30-bus test system highlight the advantages of this study. Simulation results infer that 54.27% improvement in operating time of the protection system is achievable through applying the proposed method compared to available adaptive ones because of optimizing the relay characteristics.