Electronic Thesis and Dissertation Repository

Degree

Doctor of Philosophy

Program

Electrical and Computer Engineering

Supervisor

Jin Jiang

Abstract

The focus of this thesis is on developing power management strategies for islanded microgrids, at the primary and the secondary hierarchal control layers. At the Primary Control Layer, the main objective of the proposed strategies is to achieve decentralized power management of Photovoltaic (PV) and battery storage in islanded microgrids. In contrast to the common approach of controlling the PV unit as a current source, in the proposed strategies, the PV unit is controlled as a voltage source that follows a multi-segment adaptive power/frequency characteristic curve. The strategies are implemented locally at the units using multi-loop controllers without relying on a central management system and communications, as most of the existing algorithms do.

At the Secondary Control Layer, strategies are developed to improve reactive power sharing in islanded microgrids. The proposed controllers are shown to still outperform conventional droop technique during communication failures. In addition, the reactive power sharing accuracy based on the proposed strategy is immune to the time delay in the communication channel. The sensitivity of the tuned controller parameters to changes in the system operating point is also explored. The net control action of the proposed controllers is demonstrated to have a negligible effect on the microgrid bus voltage. The proposed strategies are validated using experimental results from a 4.0 kVA prototype microgrid.


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