An enhanced automatic and autonomous excitation control for dispersed generators

The increasing presence of dispersed generators in utility networks creates problems with regards to the operation and control of the distribution system. In many cases a large part of dispersed generation is not included in communication based control systems making it difficult to coordinate the operation of these generators. This paper introduces an automatic and autonomous control strategy for intelligent control of the excitation system of the dispersed generator. It uses an expert system technique to provide voltage support and voltage following modes of excitation control as necessary. The implication of the control strategy is that the dispersed generator can be used to support the network during power system perturbations but is operated as a voltage follower under normal conditions when the network is grid connected. The expert system also makes it possible for the dispersed generator to operate isolated from the grid following the sudden loss of the connection. Simulation studies are used to demonstrate the effectiveness of the expert system under a variety of abnormal operating conditions.