Load-level-sensitive governor gains for speed control of hydrogenerators

The application of load-level-sensitive gains to proportional-plus-integral speed control of hydrogenerators is discussed. Appropriate root configuration gain functions of wicket gate position are derived for isolated resistive loads. Computer programs are used to calculate these gains from model turbine data and system parameters. Root locus tuning is used to determine appropriate gains for infinite bus loads. Simulations are presented which compare the use of constant gains to the use of these variable gains for isolated resistive and infinite bus loads. Additional resistive load simulations show the effect of a one-second digital filter on the gain function. Results indicate that the variable gain responses resemble 0.707 damping at each load level. Sample speed-transient comparisons between variable and constant gains show decreases of up to 45% in speed peak overshoot and 80% in power settling time. Load and pressure time-responses are included.<
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