Research On Stability Of Turbine In High Load Operating Condition For Goupitan Hydraulic Power Station

Rated output power of Goupitan turbine unit is 600 MW.For such large turbine unit,stability is more important than efficiency in some way.When the units began to work,unusual vibration in high load operation zone of all units was found and the output power is below design.Unusual vibration in high load operation zone of hydraulic turbine is rare,especially for turbine with large output like Goupitan.Based on vibration and noise data,two profile modification plans of runner blade and one profile modification plan of guide vane were proposed.CFD software TascFlow and CFX were used to simulate turbine flow before and after modification.Runner and draft tube flow pattern were analyzed according to the CFD result.Turbulence kinetic energy(TKE)was used to measure turbulence intensity of the flow field.Modified runner would be more stable in operation.Results of modification and CFD simulation were demonstrated in model tests.Efficiency test,pressure pulsation test,cavitation test and runaway speed test were included in analyzing the influence of modification on turbine characters.Modified runner performed better in efficiency and pressure pulsation,and performed the same in runaway speed and cavitation.Based on the model tests results,runner blade modification can be used on prototype turbine to solve the problem of unusual vibration in high load operation zone.Runner blades of Unit 1,Unit 3 and Unit 5 were modified according to the plan based on theory analysis,CFD simulation and model tests.Stability in high load operation zone of Unit 1 was improved after the second modification(plan B of runner blade modification).Pressure pulsation of all measure spots in high load operation zone were below the standard.Problems of unusual vibration in high load operation zone were solved completely by runner blade modification in Goupitan hydropower station.