Microgrid Operation and Control: From Grid-Connected to Islanded Mode

Abstract

AbstractThis chapter discusses the MG operation and control main aspects in islanded mode and its transition between the connected and islanded modes. The MG control focus relies on the hierarchical control structure, in which the primary, secondary, synchronization and autonomous operation control levels are covered. Hierarchical control is necessary to ensure the continuous operation and stability of the MG, when it changes from grid-connected to islanded mode, by an intentional or unintentional island event, during the islanded operation and when MG reconnects to the main grid. The primary control is responsible for voltage and frequency stability and power sharing between the DGs in the islanded mode. The secondary control is responsible for voltage and frequency regulation. The autonomous control is responsible for energy management to maintain the MG autonomy. When the main grid returns to its normal operation conditions, the MG synchronization control is responsible for the connection of the MG with the main grid. Some strategies proposed in the literature for each control level are introduced and simulated under islanding, islanded operation and syncronization events. A MG topology based on the CIGRE benchmark LV distribution network is employed.KeywordsMicrogrid OperationPrimary controlSecondary controlSynchronization control