15. Hierarchical Control in Microgrid

It is required to utilize several control loops together to increase reliability and performance of microgrids. The current and voltage magnitudes, frequency and angle information, active and reactive power data provide the involved feedback for normal and island mode operations of microgrid. The hierarchical control structure of microgrid is responsible for microgrid synchronization, optimizing the management costs, control of power share with neighbor grids and utility grid in normal mode while it is responsible for load sharing, distributed generation, and voltage/frequency regulation in both normal and islanding operation modes. The load control of microgrid is performed by using more sophisticated electronic devices as well as regular circuit breakers. This regulation capacity could be improved since the ESS decreases the dependency to primary power sources. Although several improvements have been experienced in microgrid control strategies, the most intensive research areas are listed as decreasing the structural instability, improving the system performance to increase reliability, monitoring the harmonic contents, scaling the control infrastructure, enhancing the operation characteristics in error states, and implementing new control algorithms for normal and islanding operation. The microgrid system has hierarchical control infrastructure in different levels similar to conventional grids. The microgrid requires enhanced control techniques to manage any level of system. Safe operation of microgrid in both operation modes and connection and disconnection between microgrid and utility grid are depended to microgrid control techniques. The controllers should ensure to operate the system regarding to predefined circumstances and efficiency requirements. The hierarchical control methods and applications of microgrid infrastructure are presented in the proposed chapter.