Control and Protection for Distribution Networks with Distributed Generators

Abstract

The connection of distributed generators to distribution networks greatly influences the performance and stability of such networks. The purpose of the dissertation has been to investigate and attempt to resolve the impacts of connecting distributed generators to distribution networks. Two main problems were defined and studied, which are the effect of distributed generators on the feeder voltage regulation and on the feeder protection schemes.

A central supervisory controller designed to regulate the feeder's voltage is presented, and the architecture of the controller is shown along with test results illustrating the ability of the controller to regulate the voltage along a feeder with distributed generators with minimum cost. In an attempt to regulate the feeder's voltage without the need for the feeder's explicit model, a multi-agent based distributed controller is proposed. The multi-agent system structure and design are illustrated, and test results comparing the performance of the two proposed controllers are shown.

The dissertation then presents an approach to extend conventional fault analysis studies to include inverter interfaced distributed generators. Such an approach is essential for the proper selection and coordination of protective devices for a feeder with distributed generators.

Finally, the dissertation illustrates the extent of deterioration a DG can cause on the overcurrent protective relay performance. An approach to solve this problem and restore the overcurrent relay performance is presented.