Synchronous power output fluctuations for an experimental open-cycle OTEC plant

A 210 kW experimental open-cycle ocean thermal energy conversion plant was completed in Hawaii in 1993, and equipped with a synchronous generator to test its connection to the local power grid. During shakedown tests, large power output fluctuations were observed. Linear mathematical models of the system were developed and numerical simulations reproduced observations well, for a given line frequency input, confirming in particular the resonant nature of a massive turbine rigidly connected to a small generator. The frequency-domain algorithm was extended to analyze the effect of inserting a fluid coupler between the turbine and the generator to eliminate large power output fluctuations. The actual installation of a fluid coupler in early 1994 allowed a validation of the model predictions.