Analysis and study on the law of the simultaneous load rejection and rejection of one machine under different S Characteristics

Abstract In order to explore the variation law of the full characteristic curve S of pumpturbine under different shutdown laws on the adjustment and protection parameters under the condition of simultaneously rejecting the operation of one unit, based on the numerical model of a proposed pumped storage power station, the approximate full characteristic curve of the head section was adopted to simulate the variation trend of the unit’s running track line and the position of the extreme point by giving the shutdown law interval and changing the shape of the S zone. The corresponding rule characteristics are obtained by summarizing and analyzing the calculation results. The results show that the extreme value of the regulating parameters related to the unit in the running process of both the rejector unit and the normally closed unit will still be affected by the shape of the S zone near the opening line. Regardless of the position of the escape point, with or without the rejector, the influence on the maximum speed rise rate is very small as the slope of the S zone increases. However, the maximum volute pressure and the minimum draft tube pressure of the unit are optimized correspondingly, which are very sensitive to the change of S characteristics, and also verify the accuracy and applicability of the corresponding law under the condition of successive rejection.