Microgrids have different protection schemes than the main grid; therefore, miscoordination is likely to occur. This is because it has possibilities of creating isolated outages in the main grid during microgrid faults.
Microgrid protection may be incompatible with the main grid protection, for example, fast acting protection in microgrids may interfere with the time delay protection and cause either unintentional tripping or delayed fault isolation.
Islanding protection is essential but not easy to achieve on the MVAC system. Synchronization between the microgrid's islanding system and the main grid's fault detection may lead to delay in islanding or reconnection at the wrong time, thus posing a threat to fault propagation.
Renewable energy based microgrids add variability in the system which makes the system dynamics challenging. The fact that it is a dynamic system for protection coordination makes it even harder to accurately model for protection.
Microgrid fault current contributions are uncertain especially with distributed generation sources. This uncertainty results in difficulties in defining the best relay setting, thus exposing the system to inadequate fault protection.
The integration of microgrids with the main grid requires real-time data sharing between the microgrids and the main grid. However, this data flow may be disrupted by failures in the communication infrastructure leading to mis-coordination between protection systems.
Delays in communication hinder observation of microgrid activities or response to problems that may arise, or protection settings that may lead to delayed fault responses or even failure in protection systems.
With the increasing number of microgrids, protection system coordination is a critical issue that needs further development in protection schemes and modeling techniques.
Effective communication network is crucial for real time operation and synchronization of the system.
Mitigating these risks is important in making smart grids of today and the future dependable and robust, especially with the growing incorporation of renewable energy.