Fitting of hydro turbine torque characteristic curves based on load rejection test

Abstract: In hydropower station transient process calculation, the hydro turbine characteristic curve had a very important impact on the calculation results. At present, the torque characteristic curve of hydro turbine is extended and fitted by the experience and mathematical methods. The simulation results are different from the test results, and it is unable to meet the requirements of accurate simulation of load shedding transient process. In this article, the treatment method of hydro turbine torque characteristic curve was studied based on load shedding test. The torque characteristic of the zero guide vane opening was identified by the shedding test data, and the whole torque characteristic curves were extended and fitted combined with the least square method. The curves were compared with the torque characteristic curves obtained by the traditional method. The results showed that the two characteristic curves are basically coincided under the large guide vane opening and relatively high efficiency, and different in the small guide vane opening. The characteristic curve obtained in this article was used to calculate the load shedding transient process under the different governor parameters, and the influence of the governor parameters on the load shedding transient process was analyzed. Two characteristic curves were used to simulate the load shedding transient process of a hydropower unit, and the simulation results are compared with the test results. Through the analysis, it is found that the characteristic curve obtained by this article can reflect the moment characteristic of the unit more accurately than the traditional method under the small guide vane opening, it is used to simulate the load shedding transition process, and the calculated results were compared with the test results, the maximum deviation of the calculated frequency is 1.05%, and the maximum deviation of the guide blade opening is 9.74%, and the simulation accuracy of the transient process is greatly improved. The research of this article can effectively guide the safe operation of hydroelectric unit.