Abstract:

Jinping II power station is located on the lower Yalong River mainstream with an installed capacity of 4800 MW, and its first unit was put into power generation in December 2012. It has four water diversion tunnels of average length 16.67km, a water diversion and power generation system that is featured with super-long tunnels and huge tunnel cross sections. At the stage of feasibility study on this system, a lot of computation and analysis have been done; at the bidding and construction drawing stages, major adjustments are made on the tunnel structures for a variety of reasons, resulting in a hydraulic transient process extremely complicated to compute. To ensure the safety and reliability of the tunnel system under hydraulic transients, a large amount of computation, analysis and model test has been conducted in previous studies. This paper summarizes the main characteristics of the system and its modification during construction, compares the calculations by different research institutions, and estimates the extreme values of system parameters for the power plant in large fluctuation conditions, the system operation stability in small fluctuation conditions, and the amplitude of generation output in hydraulic disturbance conditions by comprehensive analysis. These results are very useful for safe and stable operation of the project.