Stability Enhancement of the Microgrid under High-depth of Penetration of Electronically-coupled Resources
This thesis introduces, develops, and evaluates an on-line (real-time) methodology to optimize (adjust) a set of pre-specified microgrid parameters, e.g., those of local controllers, to maintain stability of a microgrid subsequent to each discrete-event and a small-signal perturbation. A discrete-event changes the states and necessitates a new state-space formulation and a small-signal perturbation changes the operating point of the microgrid. The focus of this work is primarily on small-signal dynamics.A hierarchical supervisory control (SC) system, which provides power management for the microgrid, embeds the algorithms of the proposed method and enables parameter adjustment. The SC (i) identifies discrete-events and small-signal perturbations, (ii) activates and executes the corresponding algorithms accordingly, and (iii) commands the required parameters adjustment to the local controllers. The embedded tools within the SC are a Newton-based power-flow analysis, a modular state-space formulation, a cluster eigen analysis, a steepest-descent optimization, and a discrete-event supervisor. An off-grid microgrid and a multi-microgrid system, are used for the reported studies. Feasibility of the SC real-time algorithms is demonstrated based on their implementation on an FPGA hardware platform. The study results show that the proposed method can effectively enhance the microgrid stability subsequent to a set of single contingencies.
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