Optimal PID gain schedule for hydrogenerators-design and application

The development and testing of a digital gain switching governor for hydrogenerators are described. Optimal gains are found at different load points by minimizing a quadratic performance criterion prior to controller operation. During operation, the gain sets are switched in depending on gate position and speed error magnitude. It is shown that, with gain switching operating, the digital governor has a substantial reduction of noise on the command signal and up to 42% faster responses to power requests. Nonlinear control strategies enable the digital governor to have a 2.5% to 2% reduction in speed overshoot on start-ups and an 8% to 1% reduction in undershoot on load rejections as compared to the analog