EP2832930A1

EP2832930A1 - Redundant system for operating spillway gates

Info

Publication number: EP2832930A1
Application number: EP13179070.1A
Authority: EP
Inventors: Hans Ingfält
Original assignee: Fortum Oyj
Current assignee: Fortum Oyj
Priority date: 2013-08-02
Filing date: 2013-08-02
Publication date: 2015-02-04
Anticipated expiration: 2033-08-02
Also published as: EP2832930B1

Abstract

The invention relates to a redundant system for operating spillway gates in a dam (1). The spillway gates (2) are provided by hydraulic cylinders (3) connected through a hydraulic circuit to a pump (17) arranged to feed hydraulic fluid through hydraulic pipelines from a tank (19) to the hydraulic cylinders (3) of the spillway gates (2) to open said spillway gates (2) when necessary. The hydraulic pump (17) is mechanically connected to a water turbine (15) to which water from the dam (1) is arranged to be fed when the water level (W) behind the dam (1) rises above an accepted level. The water flowing to the turbine (15) starts to rotate said turbine (15) and therewith the hydraulic pump (17) feeding the hydraulic cylinders (3) with hydraulic pressure to lift and open the spillway gates (2).

Description

FIELD OF THE INVENTION

The present invention relates to spillway gates used for dams, especially regulation dams for hydro power plants, water reservoirs etc. More precisely the present invention relates to a redundant system for operating spillway gates in a dam in which the spillway gates are provided by hydraulic cylinders connected through a hydraulic circuit to a pump arranged to feed hydraulic fluid through hydraulic pipelines from a fluid tank to the hydraulic cylinders of the spillway gates to open said spillway gates when necessary. The major goal of the invention is how the spillway can be opened in an emergency situation so that a dam failure is avoided.

BACKGROUND OF THE INVENTION

The production of power, in particular electric power is the main purpose and most important in hydro power plants. However, it can be said that it is as important to handle water inflow to the dam so that the dam will not be damaged or break down. The handling of water inflow is put into practice by operating the spillway gates. At present the redundant function for this generally contains complicated AC and DC backup systems including a number of failure possibilities. Existing backup power systems comprising e.g. diesel generators, battery systems etc. are inspected from time to time and during inspections faults have been detected, the worst fault being naturally that the backup system does not function at all and is not operational. The durability of existing systems is not good. They have to be refueled and in case of battery systems DC power ends rather quickly etc. Complicated systems involve high risk for failure.
Attempts have been made to improve the reliability of the operating systems for spillway gates or floodgates. Publication KR 2008099950A describes a system for floodgates in which system the gate is moved by one or two hydraulic motors engaged to transferring elements provided at the side edges of the gate. The gate may be arranged to operate automatically and/or manually.
Also other types of gates for automatic operation have been designed and constructed. One example of these can be found at Lenthalls Dam in Queensland, Australia. The spillway gates of Lenthalls Dam were designed to operate automatically in a progressive manner. The gates are provided with buoyance tanks which form the downstream skinplate of the gates. Water is led into and out of the buoyance tank depending on the water level in the dam. The gates are opening and closing according to water filling or draining from the buoyance tank. The reliability of this system has not been at a satisfied level because problems have occurred in the operation of the gates.

SUMMARY

The objective of the present invention is to provide a novel and improved redundant system for operating spillway gates. To this end the invention is mainly characterized in that the hydraulic pump is mechanically connected to a water turbine to which water from the dam is arranged to be led when the water level behind the dam rises above an accepted level, whereby the water flowing to the turbine starts to rotate said turbine and therewith the hydraulic pump feeding the hydraulic cylinders with hydraulic pressure to lift and open the spillway gates.
According to one preferred embodiment the system for feeding water to the turbine comprises a well arranged in connection with the spillway gates, the interior of which well is provided with a vertical wall dividing the well into an inlet section connected to the water in the dam through a pipeline and a discharge section from which water is discharged through a discharge channel, whereby the turbine is arranged in the discharge channel to be rotated by the discharging water.
In such embodiment the height of the vertical wall is set to the accepted water level in the dam, whereby water flows over the vertical wall from the inlet section of the well to the discharge section to rotate the turbine only when the water level in the dam is above the accepted water level.
In another embodiment water is fed from the dam to the turbine through a pipeline provided with a manually operated shut-off valve. The pipeline is further provided with a pipe loop bypassing the shut-off valve. Said pipe loop extends in the vertical direction up to the accepted water level in the dam.
The hydraulic pump and the water turbine may be directly connected one to another by their shafts. On the other hand the hydraulic pump and the water turbine may be connected one to another through a fixed gear assembly arranged between the shafts of said pump and turbine.
The present invention provides considerable advantages over prior art. As it is clear an excess water inflow to the dam has to be discharged to avoid damages. This has to be done whether or not any current power and/or backup power is available. The inventive redundant system for operating spillway gates brings along an opportunity for this.
Other advantages and characteristic features of the invention are set out below by detailed disclosure of the invention, wherein the invention is described with reference to the figures of the accompanying drawing, to the details of which the invention is not exclusively limited.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are included to provide a further understanding of the invention and constitute a part of this specification, illustrate embodiments of the invention and together with the description help to explain the principles of the invention. In the drawings:

Figure 1 is a schematic side view of the first embodiment of the inventive redundant system for operating a spillway gate.
Figure 2 is a schematic side view of the second embodiment of the inventive redundant system for operating a spillway gate.

DETAILED DESCRIPTION

Fig. 1 shows a dam 1 which is provided with a hydraulic operated spillway gate 2. The type of the shown gate 2 is a radial gate provided with radial arms 5 rotatable on a horizontal axis or trunnions 6. The gate 2 is rotated by the aid of hydraulic cylinders 3 the cylinder shafts 4 of which are fixed to the gate by articulated joints. When the gate 2 is closed water bears on the convex side of the gate. When the gate 2 is rotated the flow or actually rush of water passing under the gate 2 helps to open and close the gate 2. The rounded face of the gate 2, long radial arms 5 and trunnion bearings allow the gate to be closed with a reasonable force and power.
In accordance with the embodiment of the invention shown in Fig. 1 a well 10 or a corresponding vertical container is arranged in connection with the spillway gate 2. The well 10 is connected to water behind the dam 1 through a pipeline 11 through which water has access to the well 10. The well 10 is divided into two parts 13, 14 or sections by a vertical wall 12 so that the first part 13 of the well 10 is an inlet section 13 into which water flows through the pipeline 11. The second part 14 of the well 10 is a discharge section 14 from which water is discharged through a discharge channel 16. Water can flow in the well 10 from the inlet section 13 to the discharge section 14 only over the vertical wall 12. The height of the vertical wall 12 is in each case set to match the accepted water level W in the dam 1. So water will flow over the vertical wall 12 from the inlet section 13 to the discharge section 14 only when the water level in the dam 1 rises over the accepted water level W.
The discharge channel 16 is provided with a water turbine 15 so that the water discharging from the well 10 will rotate said turbine 15. The hydraulic cylinders 3 of the spillway gate 2 are provided with a hydraulic circuit comprising at least a tank 19 containing hydraulic fluid, a hydraulic pump 17 and necessary hydraulic pipelines connecting the tank 19, pump 17 and cylinders 3 with each other. For rotation the hydraulic pump 17 naturally needs power and therefore the shaft 18 of the turbine 15 is directly connected to the shaft of the pump 17 so that the rotation of the turbine 15 will rotate the pump 17. There may also be a fixed gear assembly between the shafts of the turbine 15 and the pump 17.
The water level behind the dam 1 is marked with W. An accepted level for the water behind the dam 1 is defined and when the water level W rises higher water starts to flow over the vertical wall 12 in the well 10 from the inlet section 13 to the discharge section 14 and further out of the well 10 through the discharge channel 16. The discharging water starts to rotate the turbine 15 and therewith the hydraulic pump 17 which feeds the hydraulic cylinders 3 of the spillway gate 2 with hydraulic pressure so that the cylinders 3 start to lift and open the spillway gate 2. To limit the hydraulic pressure to an acceptable and allowed working pressure level for the hydraulic system air is or can be mixed to the draft tube side of the water turbine. The gate 2 will open and it stays open until the water level W behind the dam 1 decreases to the accepted level whereby water will no longer flow over the vertical wall 12 in the well 10. At that point the flow amount of water discharging from the well starts to decrease and finally said flow is no longer rotating the turbine 15 and the hydraulic pump 17 wherefore due to the weight of the spillway gate 2 it starts to go down towards the closed position and simultaneously it forces the hydraulic fluid to flow in an opposite direction which makes also the hydraulic pump 17 and the turbine 15 to rotate in an opposite direction. This will go on until the spillway gate 2 is totally closed.
Fig. 1 shows further that the pipeline for the hydraulic fluid may be provided with a back pressure valve 20 before the hydraulic cylinders 3. If so is the matter the spillway gate 2 naturally cannot automatically go down even though the hydraulic pump 17 is no longer feeding the cylinders 3 with hydraulic fluid. In such case where the back pressure valve is a simple non-return valve the spillway gate 2 will stay open until the back pressure valve 20 is manually released. However, if the hydraulic circuit is provided with a back pressure valve 20, said valve may be provided with a throttling restriction so that the valve unit allows free flow in one direction, i.e. towards the cylinders 3, but a restricted flow in the other direction, i.e. towards the pump 17. This type of a back pressure valve 20 may be used, especially if there is a risk that the spillway gate might fall down to the closed position too rapidly and uncontrollably when the pump 17 is no longer feeding the cylinders 3.
Fig. 2 shows a variation of the dam 1 of Fig. 1 provided with a hydraulic operated spillway gate 2. In the embodiment of Fig. 2 the operating system of the spillway gate 2 is not provided with any well, but instead a pipeline 21, 24 is provided to connect the water behind the dam 1 to the turbine 15. A manually operated shut-off valve 22 with a valve adjusting wheel 23 is provided in the pipeline 21, 24. The pipeline 21, 24 is further provided with a pipe loop 25 bypassing the shut-off valve 22. The pipe loop 25 is arranged to extend in the vertical direction up to the accepted level W of water behind the dam 1, so that when the water level rises higher water starts to flow through the pipe loop 25 to the turbine. The system may be provided with a pipe-and-valve assembly (not shown) connected to atmosphere. By said assembly operating personnel can add air to the pipe loop 25 and stop the siphon function at a safe water level in the dam. Operating personnel can at different water levels and whenever they want open the shut-off valve 22 and thereby open the spillway gate 2 and control the opening position of the spillway gate 2. By opening manually the shut-off valve 22 the operating personnel can always get hydraulic power as back up for other hydraulic systems.
It is obvious to a person skilled in the art that with the advancement of technology, the basic idea of the invention may be implemented in various ways. The invention and its embodiments are thus not limited to the examples described above, instead they may vary within the scope of the claims.

Claims

Redundant system for operating spillway gates in a dam (1) in which the spillway gates (2) are provided by hydraulic cylinders (3) connected through a hydraulic circuit to a pump (17) arranged to feed hydraulic fluid through hydraulic pipelines from a tank (19) to the hydraulic cylinders (3) of the spillway gates (2) to open said spillway gates (2) when necessary, characterized in that the hydraulic pump (17) is mechanically connected to a water turbine (15) to which water from the dam (1) is arranged to be fed when the water level (W) behind the dam (1) rises above an accepted level, whereby the water flowing to the turbine (15) starts to rotate said turbine (15) and therewith the hydraulic pump (17) feeding the hydraulic cylinders (3) with hydraulic pressure to lift and open the spillway gates (2).
Redundant system for operating spillway gates according to claim 1, characterized in that the system for feeding water to the turbine (15) comprises a well (10) arranged in connection with the spillway gates (2), the interior of which well (10) is provided with a vertical wall (12) dividing the well (10) into an inlet section (13) connected to the water in the dam (1) through a pipeline (11) and a discharge section (14) from which water is discharged through a discharge channel (16), whereby the turbine (15) is arranged in the discharge channel (16) to be rotated by the discharging water.
Redundant system for operating spillway gates according to claim 2, characterized in that the height of the vertical wall (12) is set to the accepted water level (W) in the dam (1), whereby water flows over the vertical wall (12) from the inlet section (13) of the well (10) to the discharge section (14) to rotate the turbine only when the water level in the dam (1) is above the accepted water level (W).
Redundant system for operating spillway gates according to claim 1, characterized in that water is fed from the dam (1) to the turbine (15) through a pipeline (21, 24) provided with a manually operated shut-off valve (22).
Redundant system for operating spillway gates according to claim 4, characterized in that the pipeline (21, 24) is further provided with a pipe loop bypassing the shut-off valve (22).
Redundant system for operating spillway gates according to claim 5, characterized in that the pipe loop (22) extends in the vertical direction up to the accepted water level (W) in the dam (1).
Redundant system for operating spillway gates according to any one of the preceding claims, characterized in that the hydraulic pump (17) and the water turbine (15) are directly connected one to another by their shafts.
Redundant system for operating spillway gates according to any one of claims 1 - 6, characterized in that the hydraulic pump (17) and the water turbine (15) are connected one to another through a fixed gear assembly arranged between the shafts of said pump (17) and turbine (15).