An Integrated Security-constrained Model-based Dynamic Power Management Approach for Isolated Microgrid Power Systems



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Microgrid power systems draw lots of interests in marine, aerospace, and electric vehicle applications and are drawing increased attention for terrestrial applications. These power systems, however, are prone to large frequency and voltage deviations, when disturbances happen. Therefore, an effective power management method is needed to operate microgrids optimally, while satisfying operating and security constraints.

In this dissertation, a new Integrated Security-Constrained Power Management (ISCPM) method is presented for isolated microgrid power systems during normal/alert operating states. The new ISCPM method was formulated as a multi-objective optimal control problem, in which set-points of several system control methods are minimally adjusted, subject to operating and security constraints, over a period in the future. To solve the ISCPM multi-objective optimal control problem, an evolutionary algorithm based on the Nondominated Sorting GA II (NSGA-II) was developed, in which the optimization solver is linked to a fast simulation core. A fuzzy membership based method was developed to identify the best compromise solution.

The new power management method was implemented on a notional computer model for an all-electric ship. The NSGA-II was developed in MATLAB, by adapting a general purpose GA toolbox, IlliGAL. To conduct transient simulations during the GA iterations, the simulation core of the TSAT Tool of Tools TM software package was used. The best compromise solution identification method was developed in MATLAB.

To illustrate how the new ISCPM method works in the notional all-electric ship model, several case studies were presented. Also, to evaluate the performance of the new ISCPM method, extensive studies were conducted. For these studies, a detailed electromagnetic transient model of the system in PSCAD was used. The performance analysis addressed quality of the new method from power system operation and multi-objective optimization perspectives. The results indicated that the new ISCPM method could effectively operate the system in an overall near-optimal condition, in which security and operating constraints are also satisfied.

The application of the new power management method is not limited to all-electric shipboard power systems and it has great potential to be extended to other types of isolated microgrid power systems.