Guide-Vane Closing Schemes for Pump-Turbines Based on Transient Characteristics in S-shaped Region

2016 ◽  
Vol 138 (5) ◽  
Author(s):  
Wei Zeng ◽  
Jiandong Yang ◽  
Jinhong Hu ◽  
Jiebin Yang
Keyword(s):  
Water Column ◽  
Guide Vane ◽  
Water Hammer ◽  
Rate Of Change ◽  
Transient Processes ◽  
Transient Characteristics ◽  
Storage Station ◽  
Transitional Processes ◽  
Pumped Storage ◽  
Column Pressure

During the transitional processes of load rejection in a pumped-storage station, the S-shaped characteristics of the pump-turbines can result in relatively large water-hammer and pulsating pressures. These pressures and the high runaway speed during transient processes may directly damage the penstocks and shorten the life of the turbine. In this study, different guide-vane closing schemes for reducing the maximum transient pressures, including the water-hammer and pulsating pressures, and runaway speed were investigated, and the principles for improving the closing schemes were theoretically analyzed based on the transient characteristics in the S-shaped region. First, an analytical expression for the rate of change of relative water head during the transitional processes was deduced based on a simplified mathematical model. It reveals the relationship between the slopes of the trajectory at the pump-turbine operating points (defined as trajectory slopes) and the rigid water-column pressure, which approximates the water-hammer pressure considering compressibility. Then, based on the characteristics of the rigid water-column pressure during the transient process and the effects of guide-vane closure on the trajectory slopes, the selection method for a two-phase guide-vane closing scheme was proposed. The method included the technique for choosing the coordinates of the turning point and the closing speed of the guide vane. Furthermore, the pulsating pressures of pump-turbines were discussed under different working regions and guide-vane openings (GVOs). Considering the characteristics of the pulsating pressures and the runaway speed during the transient processes, the advantage of three-phase valve-closing schemes in controlling the pulsating pressures and the runaway speed was clarified. Finally, a series of model tests were conducted on a pumped-storage station model and the measured data fully validated the correctness of our analyses in this work.

scholarly journals Optimization of Pump Turbine Closing Operation to Minimize Water Hammer and Pulsating Pressures During Load Rejection

Energies ◽  
2020 ◽  
Vol 13 (4) ◽  
pp. 1000 ◽  
Author(s):  
Jiawei Ye ◽  
Wei Zeng ◽  
Zhigao Zhao ◽  
Jiebin Yang ◽  
Jiandong Yang
Keyword(s):  
Guide Vane ◽  
Water Hammer ◽  
Nsga Ii ◽  
Pump Turbine ◽  
Guide Vanes ◽  
Multi Objective ◽  
Spiral Case ◽  
Transitional Processes ◽  
Pumped Storage ◽  
Load Rejection Process

In load rejection transitional processes in pumped-storage plants (PSPs), the process of closing pump turbines, including guide vane (GVCS) and ball valve closing schemes (BVCS), is crucial for controlling pulsating pressures and water hammer. Extreme pressures generated during the load rejection process may result in fatigue damage to turbines, and cracks or even bursts in the penstocks. In this study, the closing schemes for pump turbine guide vanes and ball valves are optimized to minimize water hammer and pulsating pressures. A model is first developed to simulate water hammer pressures and to estimate pulsating pressures at the spiral case and draft tube of a pump turbine. This is combined with genetic algorithms (GA) or non-dominated sorting genetic algorithm II (NSGA-II) to realize single- or multi-objective optimizations. To increase the applicability of the optimized result to different scenarios, the optimization model is further extended by considering two different load-rejection scenarios: full load-rejection of one pump versus two pump turbines, simultaneously. The fuzzy membership degree method provides the best compromise solution for the attained Pareto solutions set in the multi-objective optimization. Employing these optimization models, robust closing schemes can be developed for guide vanes and ball valves under various design requirements.

scholarly journals Optimization of Guide Vane Closing Schemes of Pumped Storage Hydro Unit Using an Enhanced Multi-Objective Gravitational Search Algorithm

2017 ◽  
Author(s):  
Jianzhong Zhou ◽  
Yanhe Xu ◽  
Yang Zheng ◽  
Yuncheng Zhang
Keyword(s):  
Rotational Speed ◽  
Search Algorithm ◽  
Guide Vane ◽  
Gravitational Search Algorithm ◽  
Water Hammer ◽  
Multi Objective ◽  
Mechanical Constraints ◽  
Rise Rate ◽  
Gravitational Search ◽  
Pumped Storage

The optimization of guide vane closing schemes (OGVCS) of pumped storage hydro unit (PSHU) is the research field of cooperative control and optimal operation of pumped storage, wind power and solar power generation. This paper presents a OGVCS model of PSHU considering the rise rate of the unit rotational speed and the specific node pressure of each hydraulic unit, as well as various complicated hydraulic and mechanical constraints. OGVCS model is formulated as a multi-objective optimization problem to optimize conflictive objectives, i.e., unit rotational speed and water hammer pressure criteria. In order to realize the efficient solution of the OGVCS model, an enhanced multi-objective bacterial-foraging chemotaxis gravitational search algorithm (EMOBCGSA) is proposed to solve this problem, which adopts population reconstruction, adaptive selection chemotaxis operator of local searching strategy and Elite archive set to efficiently solve the multi-objective problem. Especially, novel constraints-handling strategy with eliminating and local search based on violation ranking is used to balance various hydraulic and mechanical constraints. Finally, simulation cases of complex extreme operating conditions (i.e., load rejection and pump outage) of ‘single tube-double units’ type PSHU system are conducted to verify the feasibility and effectiveness of the proposed EMOBCGSA in solving OGVCS problem. The simulation results indicate that the proposed EMOBCGSA can provide lower rise rate of the unit rotational speed and smaller water hammer pressure than other method established recently while considering various complex constraints in OGVCS problem.

Seepage regime of structures of the Zagorsk pumped-storage station

1992 ◽  
Vol 26 (9) ◽  
pp. 578-582
Author(s):  
L. E. Kanygin ◽  
V. N. Chernenko ◽  
A. P. Yanovskii ◽  
I. S. Ronzhin
Keyword(s):  
Storage Station ◽  
Pumped Storage

Experience in operating the Zagorsk pumped-storage station

1997 ◽  
Vol 31 (2) ◽  
pp. 130-131
Author(s):  
A. P. Kuleshov ◽  
V. I. Magruk ◽  
S. I. Mart’yanov ◽  
V. G. Rodionov ◽  
S. A. Khutoryanskii
Keyword(s):  
Storage Station ◽  
Pumped Storage

scholarly journals Optimal Model for Complementary Operation of a Photovoltaic-Wind-Pumped Storage System

2018 ◽  
Vol 2018 ◽  
pp. 1-9 ◽  
Author(s):  
Jinjin Gao ◽  
Yuan Zheng ◽  
Jianming Li ◽  
Xiaoming Zhu ◽  
Kan Kan
Keyword(s):  
Wind Power ◽  
Storage System ◽  
Optimal Solution ◽  
Multiobjective Problems ◽  
Storage Station ◽  
Compromise Optimal Solution ◽  
Pumped Storage ◽  
Economic Objective ◽  
Single Objective

An optimization model for the complementary operation of a photovoltaic-wind-pumped storage system is built to make full use of solar and wind energy. Apart from ensuring the maximum economic benefit which is normally used as the only objective, the stable objectives of minimizing the output fluctuation and variation of load and output difference are added to form the multiobjective problems because of lack of study on access capacity of photovoltaic and wind power. The model aims to increase the power benefit and reduce the output fluctuation and variation of load and output difference under the constraints of station, output balance, and transmission limitation. In a case study, four schemes including single-objective independent operation, single-objective complementary operation, and multiobjective complementary operation are compared to discuss the effect of pumped storage station on economic objective and stable objectives. Furthermore, the opposite trend of the two objectives is proved and a compromise optimal solution is given. The results indicate that the pumped storage station can effectively increase power benefit and access capacity of photovoltaic and wind power. The study can provide references to the complementary optimization of the pumped storage station and the intermittent renewable energy.

scholarly journals Impact pressure on an orifice plate by a rising water column driven by an air pocket in a vertical riser

2020 ◽  
Vol 81 (5) ◽  
pp. 1029-1038 ◽  
Author(s):  
Yu Qian ◽  
David Z. Zhu
Keyword(s):  
Water Column ◽  
Peak Pressure ◽  
Current Model ◽  
Strong Relationship ◽  
Water Hammer ◽  
Orifice Plate ◽  
Minor Effect ◽  
Initial Water ◽  
Air Pocket ◽  
Riser Height

Abstract Occurrences of storm geyser events have attracted significant attention in recent years. Previous studies suggest that using an orifice plate can reduce the intensity of a geyser event but may induce a water-hammer type of pressure on the orifice plate. This study was conducted to explore the factors that influence the pressure transients when an orifice plate was installed in a vertical riser. A novel model was developed to simulated the movement of a rising water column driven by an air pocket in a vertical riser with an orifice plate on the top. Water-hammer type of pressure occurs when the water column reaches the orifice plate. The current model accurately simulates the dynamics of the water column considering its mass loss due to the flow along the wall of the riser (film flow) and the existence of the orifice plate. It was found that the initial water column length and the driving pressure, as well as the riser material, have a strong relationship with the peak pressure. The riser diameter and riser height have minor effect on the peak pressure. The water-hammer induced peak pressure reaches the maximum when the orifice opening is around 0.2 times the diameter of the vertical riser.

scholarly journals Internal Structure of a Jet Nozzle for Coalbed Methane Mining Based on Airfoil Curves

2018 ◽  
Vol 2018 ◽  
pp. 1-17
Author(s):  
Jian Chen ◽  
Liwen Guo ◽  
Yanwei Hu ◽  
Yong Chen
Keyword(s):  
Water Column ◽  
Coalbed Methane ◽  
Pressure Fluctuations ◽  
Axial Direction ◽  
Shock Pressure ◽  
Conical Nozzle ◽  
Small Pressure ◽  
Jet Nozzle ◽  
Column Pressure ◽  
Variation Rule

Based on airfoil curves that can effectively balance the rectification and drag reduction effects in flight hydrodynamics, we designed an internal streamline structure of jet nozzle for coalbed methane (CBM) mining. The three types of nozzles originating from three typical airfoil curves are compared with the conical nozzle. Results showed that the thin-type streamlined nozzle had the largest effective shock range and least radial divergence and was thus selected as the best nozzle. Moreover, the pressure distribution at the outlet of the nozzle was found to be related to the range and number of small-pressure fluctuations near the wall. A larger number of small-pressure fluctuations and a larger range caused faster pressure of the jet water column to decay along the axial direction. Rectification with a concentrated effect also slowed down the attenuation velocity of the jet-water-column pressure between the concentration point and the nozzle. The variation rule of shock pressure with range was further determined experimentally. We found that the shock pressure of jet water column initially increased within a short distance and then decreased rapidly. The effective shock range of the thin-type streamlined nozzle in air was 1.417 times that of the conical nozzle, and the effective reaming area was 1.104 times greater. Thus, the effect of reaming was effectively improved. The length of the water column at high pressure was larger than that of the conical nozzle, and the shock efficiency was relatively high.

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