Hybrid system modeling and supervisory control of a microgrid

A new approach to designing a microgrid supervisory controller based on a hybrid automaton is described. A microgrid is defined as a small-scale local grid, comprised of various distributed energy resources (DERs), loads, and energy storage systems. Due to the intermittency of renewable generation, microgrid controllers play a vital role maintaining microgrid stability and integrity in case of an energy shortage (surplus) or when subjected to any disturbances. These controllers should be designed to provide proper control of voltage and frequency. Supervisory controllers are high level control systems that perform optimization, faults detection, protection, and energy management based on their observation from the microgrid. Supervisory controllers define set points to the local controllers for DERs and loads. In this paper, the joint continuous and discrete behavior of the supervisory controller is addressed using a hybrid controller. A complete model of the hybrid automaton (HA) is formalized and tested through one case study of a microgrid using DIgSILENT PowerFactory software. According to the results, the controller can thoroughly manage the load flow within and outside the microgrid.