scholarly journals Hydraulic Transients in the Long Diversion-Type Hydropower Station with a Complex Differential Surge Tank

2014 ◽  
Vol 2014 ◽  
pp. 1-11 ◽  
Author(s):  
Xiaodong Yu ◽  
Jian Zhang ◽  
Ling Zhou
Keyword(s):  
Pressure Difference ◽  
Mathematic Model ◽  
Hydropower Station ◽  
Maximum Pressure ◽  
Surge Tank ◽  
Hydraulic Transients ◽  
Rotating Speed ◽  
Spiral Case ◽  
Two Sides ◽  
Breast Wall

Based on the theory of hydraulic transients and the method of characteristics (MOC), a mathematic model of the differential surge tank with pressure-reduction orifices (PROs) and overflow weirs for transient calculation is proposed. The numerical model of hydraulic transients is established using the data of a practical hydropower station; and the probable transients are simulated. The results show that successive load rejection is critical for calculating the maximum pressure in spiral case and the maximum rotating speed of runner when the bifurcated pipe is converging under the surge tank in a diversion-type hydropower station; the pressure difference between two sides of breast wall is large during transient conditions, and it would be more serious when simultaneous load rejections happen after load acceptance; the reasonable arrangement of PROs on breast wall can effectively decrease the pressure difference.

Influence of Successive Load Rejections on Water Hammer Pressure of Spiral Case in Long Diversion-Type Hydropower Station

2014 ◽  
Vol 607 ◽  
pp. 551-555 ◽  
Author(s):  
Xiao Dong Yu ◽  
Jian Zhang ◽  
Cheng Yu Fan
Keyword(s):  
Numerical Model ◽  
Method Of Characteristics ◽  
Water Hammer ◽  
Hydropower Station ◽  
Maximum Pressure ◽  
Surge Tank ◽  
Hydraulic Transients ◽  
Rotating Speed ◽  
Spiral Case

Based on the theory of hydraulic transients and method of characteristics (MOC), the numerical model of hydraulic transients in water way system was established using the data of a practical hydropower station, and the probable transients were simulated. The influence of successive load rejection conditions on water hammer pressure of spiral case was analyzed. Compared with simultaneous load rejection, successive load rejection can make maximum pressure in spiral case and maximum rotating speed of runner more serious if the bifurcated pipe converging under surge tank in diversion-type hydropower station.

Application of Pressure Regulating Valve in the Hydraulic Transients of Hydropower Plant

2008 ◽  
Author(s):  
Jian Zhang ◽  
Shibo Ma ◽  
Jianyong Hu ◽  
Xiaodong Yu ◽  
Fulin Cai
Keyword(s):  
Guide Vane ◽  
Sudden Change ◽  
Pressure Rise ◽  
Hydropower Plant ◽  
Hydropower Station ◽  
Hydraulic Transients ◽  
Effective Measure ◽  
Spiral Case ◽  
Water Conveyance ◽  
Turbine Guide Vane

In the operation of the hydropower station, the sudden change of load in the large range often happen, the emergency closing law of turbine guide vane is difficult to control speed-rise and pressure-rise to the extent permitted for the length of pressure pipeline longer and discharge larger. With the development of the surge chamber of alternative technique, the pressure regulating valve is used to reduce the large pressure and speed-rise of the unit in hydraulic transients as the effective measure to saving investments. The layout of water conveyance system and process of hydraulic transients of a certain hydropower in China are analyzed, and the pressure regulating valve is installed in the spiral case inlet to meet the hydraulic regulation calculation guarantee after technical and economic comparison, for the joint action of valve and turbine guide vane, the pipeline water hammer pressure and unit speed-rise are reduced effectively. The pressure regulating valve diameter and opening and closing law in combination with the turbine guide vane are discussed in the power station, as well as the possible problems may be caused by the using of the pressure regulating valve is pointed out in theory. The achievements to scheme decision of adopting the pressure regulating valve to replace the surge chamber in high-head hydropower station with longer pressure water conveyance system can be for reference and provide the certain technological supply.

scholarly journals Study on Selection of Pressure Regulating Valve for Hydropower Station with Both Surge Tank and Pressure Regulating Valve

2018 ◽  
Vol 246 ◽  
pp. 01033
Author(s):  
Tianchi Zhou ◽  
Gaohui Li ◽  
Yimin Chen
Keyword(s):  
Transient Process ◽  
Maximum Flow ◽  
Hydropower Station ◽  
Surge Tank ◽  
Calculation Results ◽  
Practical Engineering ◽  
Spiral Case ◽  
Unit Speed ◽  
Working Principle ◽  
Selection Of

The transient process in the hydropower station with both surge tank and pressure regulating valve is quite complicated and also critical to operation safety. According to the pressure regulating valve working principle, the influence of the valve diameter on the unit speed and spiral case pressure was analyzed theoretically. Mathematical models of the surge tank and pressure regulating valve in the hydropower station were established based on the characteristic method. In a practical engineering, numerical simulation of large fluctuation and hydraulic disturbance transient process are conducted, verifying the correctness of the theoretical analysis. Based on the calculation results, three principles for selecting the valve diameter are concluded: first, making sure the unit speed meet the regulating guarantee requirements when guide vanes fast close; second, the maximum spiral case pressure of two times should be approximate to each other by controlling the superposition of surge wave and water hammer; third, the maximum flow of the valve should be as close to the rated flow of the turbine as possible. The principles are helpful for selecting the valve diameter in similar hydropower station.

scholarly journals Study on control mode of operation parameter in hydropower air chamber

2018 ◽  
Vol 246 ◽  
pp. 01038
Author(s):  
Tingyu Xu ◽  
Jian Zhang
Keyword(s):  
Water Level ◽  
Mathematic Model ◽  
Control Mode ◽  
Maximum Pressure ◽  
Initial Condition ◽  
Level Control ◽  
Reservoir Water ◽  
Air Chamber ◽  
Spiral Case ◽  
Maximum Minimum

This paper makes a deep analysis on PL control mode and static water level control mode, which could control operation parameters more conveniently and ensure safety and stability of hydropower water conveyance system. Considering the physical circumstance of monitoring parameters of the air chamber, the mathematic model of air chamber is built. On the basis of two basic criteria which are the maximum pressure at the end of spiral case and the down surge of the air chamber in hydraulic transient process, one hydropower station with air chamber is taken as an example. Determined by the effects of the upper reservoir water level on monitoring parameters, the allowable ranges of PL and air height could be consulted to control actuating and impeding the air compressor and the exhaust valve in an appropriate way. It is put forward that the maximum (minimum) product of the pressure and air height under dynamic initial condition, the maximum (minimum) air height under dynamic initial condition and static initial condition are determined by the criteria of down surge in the air chamber with large volume air (the criteria of the maximum pressure at the end of the spiral case with small volume air).

scholarly journals Numerical Modeling and Hydraulic Optimization of a Surge Tank Using Particle Swarm Optimization

Water ◽  
2019 ◽  
Vol 11 (4) ◽  
pp. 715 ◽  
Author(s):  
Khem Prasad Bhattarai ◽  
Jianxu Zhou ◽  
Sunit Palikhe ◽  
Kamal Prasad Pandey ◽  
Naresh Suwal
Keyword(s):  
Particle Swarm Optimization ◽  
Particle Swarm ◽  
Pressure Head ◽  
Transient Behavior ◽  
Maximum Pressure ◽  
Surge Tank ◽  
Hydraulic Transients ◽  
Pressurized Water ◽  
Swarm Optimization ◽  
Prime Concern

In a pressurized water conveyance system, such as a hydropower system, during hydraulic transients, maximum and minimum pressures at various controlling sections are of prime concern for designing a safe and efficient surge tank. Similarly, quick damping of surge waves is also very helpful for the sound functioning of the hydro-mechanical system. Several parameters like diameter of the surge tank, diameter of the orifice, operating discharge, working head, etc., influence the maximum/minimum surge, damping of surge waves in the surge tank, and the difference of maximum pressure head at the bottom tunnel and maximum water level in the surge tank. These transient behaviors are highly conflicting in nature, especially for different diameters of orifices (DO) and diameters of surge tanks (DS). Hence, a proper optimization method is necessary to investigate the best values of DO and DS to enhance the safety and efficiency of the surge tank. In this paper, these variables are accurately determined through numerical analysis of the system by the Method of Characteristics (MOC). Furthermore, the influence on the transient behavior with changing DO and DS is investigated and finally, optimum values of DO and DS are determined using Particle Swarm Optimization (PSO) to minimize the effects of hydraulic transients on the system without compromising the stability and efficiency of the surge tank. The obtained results show significant improvements over the contemporary methods of finding DO and DS for surge tank design.

Numerical Simulation of Hydraulic Transients in Long Corridor Surge Tank

2010 ◽  
Author(s):  
Xiaodong Yu ◽  
Jian Zhang ◽  
Arash Hazrati ◽  
Sheng Chen
Keyword(s):  
Numerical Simulation ◽  
Numerical Model ◽  
Nonlinear Partial Differential Equations ◽  
Scientific Basis ◽  
Hydropower Station ◽  
Surge Tank ◽  
Hydraulic Transients ◽  
Tank Model ◽  
New Model ◽  
Fluid Transients

A numerical model of fluid transients in long corridor surge tank, based on the equations of Saint-Venant, is developed. The implicit method of Preissman, with appropriate boundary conditions, is used to solve these two nonlinear partial differential equations. The hydraulic transients with new model and normal surge tank model are simulated and compared with model experiments. It is clarified that the new numerical model can simulate the changes of water level in long corridor surge tank and pressure along penstock realistically. The new model provides scientific basis for studying hydraulic transients of hydropower station with long corridor surge tank.

Mechanism of air-trapped vertical vortices in long-corridor-shaped surge tank of hydropower station and their elimination

2017 ◽  
Vol 29 (5) ◽  
pp. 845-853 ◽  
Author(s):  
Fang Cai ◽  
Yong-guang Cheng ◽  
Lin-sheng Xia ◽  
Yong-qi Jiang
Keyword(s):  
Hydropower Station ◽  
Surge Tank

Oscillations in Closed Surge Tanks

1943 ◽  
Vol 10 (4) ◽  
pp. A183-A186
Author(s):  
A. M. Binnie
Keyword(s):  
Small Scale ◽  
Maximum Pressure ◽  
Surge Tank ◽  
Compression And Expansion ◽  
Made In

Abstract The existing methods of predicting the oscillations in a closed surge tank are very lengthy unless drastic simplifications are made. In this paper a new and quick procedure is explained for calculating the maximum pressure and expansion of the air, which result from a sudden shutdown of the plant. Friction is taken into account, both in the pipe and also in any arrangement placed between the pipe and the tank to damp the oscillations, but the compression and expansion of the air must be assumed isothermal. Small-scale experiments confirmed the expectation that the observed maximum pressures would be greater than the theoretical. The shutdown of a big plant is, however, not instantaneous, and the theory may be expected to yield results sufficiently accurate for the purpose in view.

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