Hybrid control for micro-grid based on hybrid system theory
With the rapid increase in the rate of distributed generation ((DG) penetration depth, the issues of improving micro-grid transient become more significant. This paper investigates a two-level hierarchical hybrid control consists of continuous local controller for each DG unit at the first level coordinated by discrete supervisory control strategies at the secondary level for transients performance enhancement of micro-grid with various DG units following pre-planned or accidental switching events. The discrete supervisory control strategies are established based on information fusion technique by using wide-area measurements (WAM) in order to coordinate switching each DG subsystem into apposite operation mode following large disturbances. The continuous local controller for each DG unit is designed based on multiple Lyapunov stability theory incorporating linear matrix inequality (LMI) techniques in order to regulate the set point of each DG subsystem to reach the best performance and acceptable operation indexes. The effectiveness of the proposed hybrid control is demonstrated through simulation examples.