A nonlinear evaluating function dealing with wicketgate closing rate optimization was presented, and the multioperation point optimization method is proposed based on genetic algorithm. The wicketgate closing rate of a real hydropower station was optimized by utilizing the proposed function and optimization model and the results were compared with those optimized by means of the existing linear evaluating function. For the optimized closing rate by using the linear evaluation function, the maximum speed rise is 49.4%, which is near the control value (50%), and the safe margin is 0.6% only; but the safe margins of both the maximum pressure at the end of spiral casing and the minimum pressure at the inlet of draft tube are 4.717 and 2.812 m, which are relatively high. For the closing rate optimized with the proposed nonlinear evaluation function, however, although the safe margins of both the maximum pressure at the end of spiral casing and the minimum one at the inlet of draft tube drop to 2.501 and 1.765 m, the maximum speed rise is 46.1% and the safe margin rises to 3.9%. The simulated results show that the optimized wicketgate closing rate with the just proposed nonlinear evaluating function can keep safety margin in a proper range for every optimization objective. Multioperation point optimization method is proven to be accurate and the optimized closing rate is universal to different hydrotransient cases. Such a method plus the proposed nonlinear evaluating function can achieve a relatively equalized distribution of safety margin for every optimization objective in different cases.
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