Impact of fuel cells on load-frequency control in power distribution systems

This paper describes a concept of a distribution system that has enough generation to track its load without the help of a substation. Specifically, it addresses the presence of solid-oxide fuel cells in the distributed generation mix. Two control loops are proposed: 1) to guarantee that the fuel cell is protected by maintaining its cell utilization within its admissible range and 2) to track load changes and regulate the frequency. The two respective loops are called primary and secondary loops. The primary loop maintains constant the ratio of stack current to input fuel flow, and the secondary loop tracks the load and regulates the frequency. A distribution area error (DSE) is introduced to formulate the frequency-control problem. The secondary loop feeds back this DSE signal. Tuning of the parameters is performed using genetic algorithms.