ADAPTIVE CONTROL OF EMBEDDED GENERATORS

摘要

The potential of a significant amount of dispersed generation operating in the distribution system creates the need to ensure that they can maintain supply even when isolated from the main power grid. When operating in parallel to the grid the excitation and governor systems have to be controlled in a manner that reduces their impact on the overall control and operation of the distribution system. However, this control requirement is unsuitable for isolated operation and can lead to the deterioration of quality of supplies when the grid connection is lost. It is therefore desirable that the control strategy is one that would automatically adapt the dispersed generator to the current operating situation be it in parallel with or isolated from the grid supply. Although communication of information between the dispersed generators offers an immediate solution, in most circumstances it is impractical. Essentially the requirements call for control strategies that utilise local information derived from terminal quantities. This paper introduces an automatic control strategy which autonomously adapts the dispersed generator's control system for parallel or isolated operation. It consists of an expert system technique for the control of the excitation system and an automatic governor control system. The control strategy is such that the dispersed generator uses a voltage follower system and regulates active power in the parallel mode of operation, but regulates the voltage and frequency in the isolated mode. Simulation results obtained from a small distribution system with dispersed generation are presented to demonstrate the effectiveness of the control strategy under a variety of operating conditions.