Impact of Tail Water Fluctuation on Turbine Start-Up and Optimized Regulation

Small hydropower plants are usually run-of-river with a poor adjustment capacity, and, therefore, large tail water fluctuation may be induced during flood discharge. Meanwhile, the turbine units need to be quickly started-up due to the regulation requirements of the power grid. However, failures of the start-up and grid connection are often encountered because of severe tail water fluctuation. In order to achieve the rapid and stable start-up under tail water fluctuations and to reduce the negative effect of start-up on turbine runner blades, the fluctuation law of the tail water from flood discharge model test is introduced as the boundary condition. A multi-objective comprehensive (MOC) index is proposed to optimize the parameters of the governor. Then the impacts of the tail water amplitude and frequency on the start-up are simulated and analyzed. Moreover, the start-up characteristics under the Integral Time Absolute Error (ITAE) index and the MOC index are compared through particle swarm optimization (PSO). The results show that both indices can ensure the rapidity of start-up under tail water fluctuation, whereas the MOC index can achieve a more stable start-up process. Therefore, the MOC index has a better stability and a less negative effect on the turbine runner blades.