Spillway Gate Research Articles

Evolutionary algorithm-based fuzzy PD control of spillway gates of dams

In this paper, an evolutionary algorithm (EA)-based fuzzy proportional-derivative (PD)-type controller is employed to reservoir control of dams with the purpose of operating spillway gates during any flood of any magnitude, which is not predictable beforehand. EA is used to evolve the main parameters of the fuzzy PD controller. The use of the EA, in conjunction with a systematic neighborhood structure for the determining of fuzzy rule-base parameters, leads to a significant improvement in the performance of the controller. The major objective of the controller is to achieve better system performance over the conventional control methods. In order to demonstrate the high performance of the presented method, we simulate the control system using different probable inflow hydrographs of various magnitudes. The simulation results indicate that the EA-based fuzzy PD controller not only performs an accurate and efficient solution, but also exhibits more desirable and reliable results than the conventional approaches.

Dam overtopping risk assessment considering inspection program

Safety inspection of large dams in Taiwan is conducted every 5 years. The practice does not take into consideration uncertainty of dam conditions. The goal of this study is to determine the optimal dam inspection interval under the consideration of overtopping risk incorporating uncertainty gate availability. In earlier studies, assessment of overtopping risk only considered the uncertainties in reservoir properties and natural randomness of hydrologic events without giving much thought to the availability of spillway gates. As a result, the overtopping risk could be underestimated. In this study, an innovative concept is proposed to evaluate dam overtopping by taking into account spillway gate availability. The framework consists of three parts: (1) evaluation of conditional overtopping risk for different numbers of malfunctioning spillway gates; (2) evaluation of spillway gate availability; and (3) dam inspection scheduling. Furthermore, considerations are given to overtopping risk, inspection cost, and dam break cost for determining the optimal inspection schedule. The methodology is applied to the Shihmen Reservoir in Taiwan and to evaluate its time-dependent overtopping risk. Results show that overtopping risk considering the availability of the spillway gates is higher than the one without considering the availability of the spillway gates.

Controlling spillway gates of dams by using fuzzy logic controller with optimum rule number

Reservoir operation of dams during floods is a complex, nonlinear, nonstationary control process and is significantly affected by hydrological conditions which are not predictable beforehand. In this paper, an operation method based on fuzzy logic control is presented for the operation of spillway gates of reservoirs during floods. The rule base of fuzzy logic controller is optimally determined by using tabu search algorithm which is a modern popular heuristic algorithm. Simulation results demonstrate that the proposed approach based on fuzzy logic controller designed by using tabu search produces an accurate and efficient solution for the reservoir operation of dams.

Review of Hydraulics of Spillways and Energy Dissipators by R. M. KhatsuriaHydraulics of Spillways and Energy DissipatorsMarcel Dekker0-8247-5789-0$199.95/£115

In the past decade, a number of books were written for hydraulic engineering, including Hydraulics of Open Channel Flow by Sergio Montes 1998 , Dam Hydraulics by Daniel L. Vischer and Willi H. Hager 1998 , Hydraulic Structures by Pavel Novak et al. 2001 , and The Hydraulics of Stepped Chutes and Spillways by Hubert Chanson 2002 . The present book is a welcomed addition to engineering knowledge because a number of topics relevant in the design of hydraulic structures related to dam engineering are highlighted, and issues developed mainly in India are now internationally available. The book contains four sections: “Spillways,” with 18 chapters; “Energy Dissipators,” with 7; “Cavitation and Air Entrainment” with 3; and “Hydraulic Modeling,” with 1 chapter. Section one covers over half of the book; whereas, Section two has 25%, Section three has 10%, and Section four contains 30 pages. Section one opens with introductionary chapters relating to spillways in general and their selection for a particular spillway type in terms of site conditions, design flood, and cost. The relevant knowledge on the Ogee spillways is presented in Chapter 4 including crest shape, discharge characteristics, and crest pressures. The side channel spillway is highlighted in Chapter 5, with the determination of the free surface profile, shock waves due to chute contractions and bends, and the effect of piers. Chapter 6 relates to stepped spillways with the possible three flow regimes, the hydraulic features of skimming flow, air entrainment, and energy dissipation. Siphon spillways are treated in Chapter 7 with a description of the hydraulic action, design considerations and the discharge capacity, effects of waves, and the stability aspects of those structures. Shaft spillways are then described in Chapter 8, with particular attention to the free intake flow type, both the water and air entrainment characteristics along the shaft and the downstream tunnel, air release systems, and the main aspects of vortex drops. In Chapter 9, labyrinth spillways are accounted for in terms of the various design parameters, discharge characteristics, and practical issues. Tunnel spillways are investigated in Chapter 10, yet the important aspects of the air-water flow are not discussed. Chapter 11 relates to the free jet and straight drop spillways with a particular emphasis on the air entrainment characteristics of falling water jets, the use of nappe splitters, and the development of plunge-pool scour. Fuse plugs are described in Chapter 12, including some design guidelines in terms of discharge. Chapter 13 relates to spillways used for flood and sediment disposal and Chapter 14 to unlined spillways, thereby accounting for rock erosion. Inflatable rubber weirs are treated in Chapter 15 by accounting for hydraulic and the structural design aspects. Means to protect spillways from overtopping are discussed in Chapter 16, and spillway crest gates receive attention in

Selective opening of hydroelectric dam spillway gates for downstream migrant eels in New Zealand

Abstract Selective opening of the Patea hydroelectric dam spillway gates was examined for its potential to provide safe downstream passage for sexually mature (silver) eels in New Zealand. During autumn 2000, one of the spillway gates at the 82‐m high Patea Dam was opened for 2.5 h and a large fyke net set across the river about 1.5 km below the dam. Fifty one live endemic longfin eels Anguilla dieffenbachii (Gray), 60 live shortfin eels Anguilla australis (Richardson), and eight dead shortfin eels were captured. All but three of the eels caught were downstream migrants, and aside from the dead eel, only a small portion (5%) had external signs of injury. It was likely that the majority of the eels captured passed over the spillway, but some may have originated from the section of river between the dam and the net or gone through the turbines. To further test the ability of eels to survive passage over the spillway, three controlled spills were made in autumn 2001 and 102 eels released immediately upstream of the partially opened spillway gates. A net stretched across the base of the concrete spillway was used to recover the eels. Most of the eels recovered from the spillway had low levels of injury. However, during the third controlled spill, 10 wild migrant eels were also caught with none showing any external signs of injury. This indicated that the damage noted on the recovered eels were the result of handling rather than passage over the spillway. It was concluded that selective opening of hydroelectric dam spillway gates can provide safe downstream passage for migrant eels.

Evaluation of the Flood Mitigation Function of an Agricultural Dam with Spillway Gates

Evaluation of the Flood Mitigation Function of an Agricultural Dam with Spillway Gates

Fuzzy Logic Based Operation of Spillway Gates of Reservoirs during Floods

In this technical note, a new and efficient control method based on fuzzy logic is proposed for the real-time operation of spillway gates of a reservoir during any flood of any magnitude up to the probable maximum flood. To demonstrate the performance of the proposed method, we simulate the control system using different probable overflow hydrographs. The results of the proposed control method are compared with the results of the conventional control methods. The results from the simulations indicate that the proposed method exhibits superior performance over conventional reservoir flood operation with much more reliable results.

Artificial neural networks and fuzzy logic based control of spillway gates of dams

AbstractIn this paper a new and efficient control method based on fuzzy logic is proposed for real‐time operation of spillway gates of a reservoir during any flood of any magnitude up to the probable maximum flood. Artificial neural networks are used to model the non‐linear relationship among the main variables of the reservoir under consideration. In order to demonstrate the performance of the proposed method, we simulate the control system using different probable overflow hydrographs. The results of the proposed control method are compared with the results of the conventional control methods. The results obtained from the simulations indicate that the proposed method exhibits superior performance over the conventional reservoir flood operation, with much more flexible results. Copyright © 2004 John Wiley & Sons, Ltd.

Determining fuzzy membership functions with tabu search—an application to control

This paper presents a new approach for the optimum determination of membership functions for a fuzzy logic controller based on the use of tabu search algorithm. To demonstrate the efficiency of the suggested approach, a specific control problem—operation of spillway gates of reservoirs during floods is selected. Simulation results showed that the proposed approach could be employed as a simple and effective optimization method for achieving optimum determination of membership functions.

Ice Adhesion to Locks and Dams: Past Work; Future Directions?

Adhesion of ice to surfaces creates problems for many industries, including aviation, hydropower, telecommunications, navigation, electrical distri- bution, and all forms of transportation. Specific problems at locks and dams include ice buildup on lock walls and miter gates, and spillway gate freeze up, preventing opening on short notice. At present, ice removal techniques are both costly and time-consuming. In an effort to reduce the cost, time, and physical labor associated with ice removal, much research on ice adhesion has been done. This work ranges from theoretical studies to microscopic investigations and full- scale field tests. The main focus of all of these studies is how to lower ice's adhesive strength, thus easing ice removal. Three principal methods to lower ice's adhesive strength have been pursued—electrical, chemical, and mechanical. Of the three methods, the mechanical removal of ice has received the least amount of attention. Three approaches have been taken with regard to electrical methods. They are using heaters, creating an electrical pulse that mechanically breaks the ice, and applying a direct current bias to change the ice's adhesion. The search for a low adhesive coating or material has by far received the most attention of any method pursued for lowering ice's adhesive strength. A class of chemicals con- taining polysiloxanes has shown promise in providing a low adhesion surface. Based on this review, we recommend that an electroexpulsion method developed for the space shuttle and a newly formulated polysiloxane be tested as to their feasibility in the lock and dam environment.

Two-dimensional elastica analysis of equilibrium shapes of single-anchor inflatable dams

Several types of inflatable dams are considered. These are long, air-inflated, cylindrical structures on a rigid foundation. Sometimes one of the long edges of a sheet is folded back to the other edge, and then the two edges are clamped to the foundation along a single anchoring line. A second configuration can be modeled as two sheets attached along two long edges, with one edge anchored and the other free to lift as air pressure is applied between the sheets. Another device treated here is a hinged spillway gate lifted by an inflatable bladder. The cross section of the dam or bladder is analyzed as an inextensible elastica. The governing equations and boundary conditions are formulated for each case, and shooting methods are utilized to obtain numerical solutions for the equilibrium shapes. The effects of the internal air pressure and the external water height are investigated.

FINITE ELEMENT ANALYSIS OF FREE SURFACE FLOW THROUGH GATES

Two-dimensional finite element analyses of two types of gate—(i) a conduit gate with pressure flow upstream of the gate and free surface flow downstream of the gate and (ii) a sluice gate with free surfaces both upstream and downstream of the gate—are done using ideal fluid theory. The conduit gate problem is solved using both Φ- and Ψ- formulations. Various methods of satisfying the boundary conditions were tested for both formulations. The ψ-formulation developed in the present study is found to converge faster for flows with Froude numbers less than 4, which are common in sluice gates. The results obtained from the present study are compared with results from analytical and experimental techniques available in the literature. The ψ-formulation developed in the present study is then used to solve the spillway gate problem, for which no analytical solution is available.

FINITE ELEMENT ANALYSIS OF FREE SURFACE FLOW THROUGH GATES

Two-dimensional finite element analyses of two types of gate—(i) a conduit gate with pressure flow upstream of the gate and free surface flow downstream of the gate and (ii) a sluice gate with free surfaces both upstream and downstream of the gate—are done using ideal fluid theory. The conduit gate problem is solved using both Φ- and Ψ- formulations. Various methods of satisfying the boundary conditions were tested for both formulations. The ψ-formulation developed in the present study is found to converge faster for flows with Froude numbers less than 4, which are common in sluice gates. The results obtained from the present study are compared with results from analytical and experimental techniques available in the literature. The ψ-formulation developed in the present study is then used to solve the spillway gate problem, for which no analytical solution is available.

Design Guidelines for Spillway Gates

This article discusses the most common types of spillway gates including radial gates, vertical lift gates, and flap gates including inflatable gates, and their application. Design considerations for each type are explained. Design and application considerations for different types of spillway gate operators are also included. Items covered for gates include gate geometry, gate proportions, location of gate hoists, location of gate trunnions, trunnion anchorage arrangements, gate seals and sealing arrangements, use of dogging devices, wave deflectors, flow splitters, corrosion protection including use of cathodic protection, and ice problems associated with spillway gates. Items covered for hoists include selection criteria for hydraulic and mechanical hoists, functional requirements of the hoists, use and type of position indicators, normal speed of opening and closing, use of automatic controls, the need for maximizing the minimum opening, and automatic stopping of the gates at set intervals to prevent unintentional spilling. Permissible leakage rate through the gates is also included.

Finite element analysis of cast iron spillway gate wheels

A number of failures involving cast iron wheels on control gates at various hydro-electric generating stations in Manitoba prompted Manitoba Hydro to undertake an investigation to determine their failure capacity under static loading. The function of these wheels is to allow vertical lift gates at hydro-electric generating stations to open and close under hydrostatic load with minimal resistance. The investigation involved an extensive experimental program, where eleven 685 mm diameter wheels were tested to failure. Also, a detailed finite element analysis of the wheels was performed. This paper deals with the results from the finite element analysis.

Behavior of Cast‐Iron Spillway Gate Wheels

The vertical lift fixed‐wheel gate is a common type of control gate found at hydroelectric generating stations. The material used for the wheels of such gates ranges from cast iron for the older vintage stations to alloy and low‐carbon steels in more modern stations. In recent years, several cast‐iron wheels on such gates have failed in service. An experimental program, sponsored by Manitoba Hydro, was undertaken at the University of Manitoba to study the performance characteristics of cast‐iron wheels and to determine their failure capacity under static loading conditions. Eleven 685‐mm‐diameter cast‐iron wheels obtained from a spillway gate at the McArthur Falls Generating Station in Manitoba were tested to failure under radial and a combination of radial and lateral loads. The material properties were obtained from standard coupon testing. In addition to the experimental work, the elastic behavior of cast‐iron gate wheels was investigated using the ANSYS finite‐element (FE) program. The results from the experimental program and the finite‐element analysis were compared to the results predicted by current design criteria and a number of recommendations for improving these criteria were made.

Diversion of stream through hydroelectric stations with high dams during construction

1. The scheme of diverting the flow according to steps of construction of especially high dams is the basis of the site organization plan and also has a substantial effect on the design and layout of the main structures of a hydrostation. 2. The best scheme of constructing a dam is that for which stream diversion is carried out through one level of spillways, which later is used as the service level. If it is impossible to accomplish this scheme, it is necessary to provide the possibility of operating a lower level of spillways until the higher level is completely ready for passing the flow, including floods. Schemes calling for “fleeing from water” should be completely eliminated. 3. Designs of spillway gates of high dams, including the materials used in them, should be tested on simpler and less important structures. The layout of even temporary gates should provide the possibility of repair of the movable parts and seals. 4. The configuration of the spillway channels and the location of the regulating gates should be designated so as to eliminate or limit the possibility of the occurrence of conditions for the development of cavitation processes. The best solution in this case is to locate the regulating gate at the outlet of the pressure part of the spillway. 5. The scheme of dissipating the energy of the flow in a stilling basin at heads of more than 120 (140) m also has substantial shortcomings complicating the preparation of the structures for stream diversion by steps of construction.

Analysis of Flows with Initially Unknown Discharge

Two-dimensional and axisymmetric gravity flows of ideal fluids are calculated by means of the finite element method. A generalized iteration technique is used for the discharge and free-surface determinations. The model can be employed in a versatile manner due to a flexible network structure. Significant principles for the control of the entire network movement are presented for free-surface problems. This yields, apart from theoretical discharge coefficients, the free-surface profiles and the velocity and pressure distributions over the entire flow domain. Solutions for flow under sluice gates, under a spillway gate, over spillway crests, and over a morning-glory shaft spillway are given.

Closure to “Spillway Gate Vibrations on Arkansas River Dams”

Closure to “Spillway Gate Vibrations on Arkansas River Dams”

Experience with the operation of gates at the Lenénnergo hydroelectric plants

1. Among all the different types of spillway gates, the best operating qualities were exhibited by the segmental gate with closed transverse sections. This type of gate may be recommend ed for use undersimilar climatic conditions as an operative gate for regulating the water level in the reservoir. Among the gates which may compete with segmental gates, we may mention the semihhydraulic cylidrical and drum gates. 2. Among the gates kept in storage during the winter and placed only during the high water period, with full opening of the spillway passages, the most satisfactory ones are the vertical-lift gates. 3. A progressive type of maintenance repair gate for spillway openings is that represented by the floating gates installed at the Svetogorsk and Lesogorsk plants; a more refined type of floating gate has been developed by Professor V. G. Gebel. 4. Favorably operating turbine gates have been those flat gates used at the Lesogorsk and Svetogorsk plants. which are characterized by their high degree of watertightness, small weight, compactness of the upper elements owing to the low location of the hoist, and originality of the operation blocking. 5. Excellent operating characteristics are shown by the electric hoists for the maintenance stop logs in the outlet at the Volkhovsk plant. The use of this equipment is to be recommended. 6. The arrangement of the grooves for the maintenance repair gates and the trashracks in dams built across rivers should be established on the basis of the volume and type of trash in the river.