A protection method for microgrids based on information sharing

Microgrid is a low-voltage network with distribution generation which can be operated in parallel to the utility grid or in an islanded condition. The protection of microgrid faces a real challenge due to its changable operating conditions. Under islanded mode, large fault current in-feed from the network is no longer available. In addition, most of the renewable energy sources are connected to the microgrid through inverter interfaces with fault-current limiting capability, thus simple overcurrent protection will not be sufficient. The ability of the protection to adapt to the realtime operating conditions of the microgrid is therefore an essential requirement, which in turn requires high speed communications to ensure information can be shared by the protection devices within a microgrid. This paper presents a fault analysis of a practical university campus microgrid and proposes a protection scheme based on information sharing technology. A microgrid management centre (MMC) is available which communicates with all the devices within the microgrid and reconfigures the protection under different operating conditions. In addition, protection devices also have the ability to communicate with each other to share their local information. The scheme is developed through studies and fault analysis of this specific microgrid.