A hybrid PI and PD type fuzzy logic controller for automatic voltage regulation of the small alternator

Traditionally the automatic voltage regulator (AVR) of small salient-pole alternators has been implemented using analogue electronic circuitry, typically employing PID control. However, for new generator set operating modes, found in a deregulated environment, more sophisticated control is sought. Digital technology can facilitate these new control algorithms. This paper concerns itself primarily with the development of such a control algorithm. Fuzzy logic is applied here to offer PID type control. This control structure enables conventional PID design techniques to be used, which aids scaling parameter selection. Results of tests carried out on three different alternators, rated at 30 kVA, 45 kVA and 450 kVA, are provided. The tests performed include load application and rejection, and start-up.