| With the continuous adjustment of the energy structure,the transformation of renewable energy such as wind energy and solar energy to replace fossil energy is steadily advancing,and in this context,the improvement of the energy peak shaving system cannot be delayed.Pumped storage power stations play a key role in grid peak shaving with their unique advantages,and the "Pumped Storage Medium and Long-term Development Plan" proposes that by 2025,the total scale of pumped storage will reach more than 62 million kilowatts;By2030,the total scale of pumped storage capacity will reach about 120 million kilowatts.In the construction of pumped storage power stations,the calculation of hydraulic transition process is a key issue related to the operation safety of power stations.Its calculation accuracy has attracted much attention,and it has important academic and engineering value to study the calculation model of hydraulic transition process of pumped storage power station.In this paper,the hydraulic transition process of pumped storage power station is calculated based on the wave tracking calculation method,the theoretical equation of the wave tracking calculation method is first given,the calculation model of the boundary of typical pipeline and the boundary of the pressure regulating well is derived,and the full characteristic curve of the pump turbine is modified by the Suter conversion method,the interpolation expression of the full characteristic curve is obtained by the linear interpolation method,and the calculation model of the boundary of the pump turbine is established by combining the head balance equation and the inertia equation of the unit.Secondly,the hydraulic experimental model of the diversion power generation system of Nyerere Hydropower Station was built,and the formulation and implementation of the experimental working conditions were completed,and the comparison between the calculation results of the experimental working conditions and the experimental results showed that the calculation results were consistent with the experimental results,and the calculation error was reduced by considering the difference in wave velocity of different branch pipes.By adding nodes inside the pressure pipeline,the hydraulic parameters at any one position can be changed.Wave parameters visually show the connection between flow rate,pressure changes within the water transmission system,and surge fluctuations in the regulator well throughout the hydraulic transition.Finally,based on the relevant parameters of Hongping pumped storage power station,the large fluctuation transition process is calculated by Excel VBA compilation program,and the following conclusions are obtained:(1)The calculation model of pumped storage power station established based on wave tracking method is suitable for the load dumping condition of the turbine and the pumping and power off condition of the water pump and has good accuracy,and the calculation results can reflect the extreme value of the transition process and reflect the trend of hydraulic transients in the whole process,and the calculation error is mainly caused by the limitations of the calculation data and one-dimensional calculation.(2)After the load of the turbine power generation condition,the volute pressure rises,the tailwater pressure decreases,and the water hammer effect is obvious,but it tends to stabilize quickly under the regulation of the surge tank;The surge water level fluctuation time of the pressure regulating well is long and periodic,and the fluctuation amplitude decreases with time.During the whole transition process,the unit experienced the turbine zone,the braking regime and the reverse pump zone,and finally reached the turbine area with a small opening;The transition process line of the unit after the Suter conversion is smoother,which shows that the Suter conversion is effective.(3)When the guide vane is normally closed,the unit experiences the pump zone,the pump braking regime,the turbine zone,and the turbine braking regime,and the unit reverses about 1 times the rated speed;When the guide vane refuses,the unit experiences the pump condition,the pump brake condition,the turbine condition,the water turbine mechanism,and the reverse pump condition,and the final working condition point moves back and forth in the "S" area,the hydraulic parameters change sharply,and the maximum reversal speed is greater,about 1.2 times the rated speed. |
