Method for setting opening of draft tube feed valve

Abstract

To provide a method for setting opening of a draft tube feed valve that performs water turbine efficiency testing process in addition to a draft tube feed valve opening measurement process to achieve optimum states of both draft tube feed valve opening and water turbine efficiency.SOLUTION: A method for setting opening of a draft tube feed valve includes: a draft tube feed valve opening measurement step of setting opening of a draft tube feed valve relative to opening of a predetermined guide vane; and a water turbine efficiency testing step of calculating water turbine efficiency at the opening of the draft tube feed valve and performed together with the draft tube feed valve opening measurement step.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] An embodiment of the present invention relates to a method for setting the opening degree of a draft pipe air intake valve. [Background technology]

[0002] One type of water turbine installed in a hydroelectric power plant is the Francis turbine. A conventional configuration of a Francis turbine, which is a type of water turbine, will be described with reference to FIG. 5. In a Francis turbine 50, water guided from a penstock 1 through an inlet valve 2 flows into a casing 3, and the amount of water is adjusted through stay vanes and guide vanes (both not shown) installed in the casing 3. When the water whose amount has been adjusted flows into a runner 4, the runner 4 receives water pressure from the water and rotates. When this rotational energy is transmitted to a generator (not shown) through a water turbine shaft 5 of the runner 4, the generator (not shown) generates electricity. The water passing through the runner 4 flows from the outside to the inside (the water turbine shaft 5 side) in the axial direction of the runner 4, and is then discharged to the outside through a draft pipe 6.

[0003] Here, it is known that a phenomenon called cavitation occurs inside the runner 4 and the draft pipe 6, in which a vacuum part generated in the water collides with a part of high water pressure, generating a shock wave. Cavitation increases turbine vibration and noise, erodes the turbine, and reduces turbine efficiency and generator output. Therefore, it is necessary to reduce cavitation in order to operate a hydroelectric power plant efficiently. In particular, in order to suppress the generation of a vacuum part inside the draft pipe 6, a draft pipe air intake pipe 7 is provided on the draft pipe 6 in the conventional Francis turbine 50, and air is supplied from the outside to the inside of the draft pipe. At that time, the amount of air supplied is controlled by adjusting the opening of a draft pipe air intake valve 8 provided on the draft pipe air intake pipe 7. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 10-103211 Summary of the Invention [Problem to be solved by the invention]

[0005] Conventionally, the opening of the draft pipe air intake valve 8 is set qualitatively in a test carried out before the turbine is put into operation, by varying the opening of the draft pipe air intake valve 8 relative to the opening of a predetermined guide vane (not shown) and measuring the turbine vibration, shaft runout, noise, and the like. In addition, it is common to carry out a draft pipe air intake valve opening measurement process, which is a test for setting the opening of the draft pipe air intake valve 8, and a turbine efficiency test process for measuring the final turbine efficiency, separately. However, efficient operation of a hydroelectric power plant can only be achieved by setting both the opening of the draft pipe air intake valve 8 and the turbine efficiency to optimal values, and therefore, with the conventional method, it may be difficult to set both of these values ​​to optimal values.

[0006] Therefore, the problem that the present invention aims to solve is to provide a method for setting the draft pipe air intake valve opening, which performs a turbine efficiency test process in conjunction with the draft pipe air intake valve opening measurement process, and which can optimize both the draft pipe air intake valve opening and the turbine efficiency. [Means for solving the problem]

[0007] In order to achieve the above object, the method for setting the opening of the draft pipe air intake valve of an embodiment includes a draft pipe air intake valve opening measurement process for setting the opening of the draft pipe air intake valve relative to a predetermined guide vane opening, and a turbine efficiency testing process for calculating the turbine efficiency at the opening of the draft pipe air intake valve, the turbine efficiency testing process being carried out together with the draft pipe air intake valve opening measurement process. [Brief description of the drawings]

[0008] [Figure 1] A flow chart showing an example of a conventional hydroelectric power plant field testing process 100. [Diagram 2] FIG. 1 is a schematic diagram showing an example of the positional relationship between a measurement means and a Francis turbine 50 when performing the draft pipe air intake valve opening measurement process 120. [Diagram 3]FIG. 1 is a schematic diagram showing an example of the positional relationship between a measurement means and a Francis turbine 50 when performing a turbine efficiency test process 150 using an ultrasonic method. [Figure 4] 1 is a flowchart showing an example of a hydroelectric power plant on-site testing process 200 according to an embodiment, where (a) is a flowchart showing an example of a hydroelectric power plant on-site testing process 200 in which the measurement of the turbine operating state in the draft pipe air inlet valve opening measurement process 120 and the calculation of the turbine efficiency in the turbine efficiency testing process 250 are carried out in parallel, and (b) is a flowchart showing an example of a hydroelectric power plant on-site testing process 200 in which the turbine efficiency testing process 250 is carried out following the draft pipe air inlet valve opening measurement process 120. [Diagram 5] Schematic diagram showing an example of a Francis turbine 50 DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, a method for setting the opening degree of a draft pipe air intake valve according to an embodiment of the present invention will be described in detail with reference to the drawings. Note that the embodiment shown below is an example of an embodiment of the present invention, and is not intended to limit the scope of the invention. In addition, in order to more clearly distinguish the difference between the embodiment of the present invention and the conventional one, a conventional on-site test process of a hydroelectric power plant will be described first as a comparative example, and then the on-site test process of a hydroelectric power plant of this embodiment will be described. In this case, the same parts or parts having similar functions will be given the same or similar symbols, and their description may be omitted. Also, the dimensional ratios of the drawings may differ from the actual ratios, and part of the configuration may be omitted from the drawings.

[0010] (Comparative Example) A conventional hydroelectric power plant field test process 100 will be described with reference to Fig. 1. Fig. 1 is a flowchart showing an example of the conventional hydroelectric power plant field test process 100. As shown in Fig. 1, the conventional hydroelectric power plant field test process 100 includes a waterless test process 110, a draft pipe air inlet valve opening measurement process 120, an output opening test process 130, a load test process 140, and a water turbine efficiency test process 150.

[0011] The waterless test process 110 refers to various tests carried out before the first rotation test in the hydroelectric power plant field test process, such as the guide vane opening / closing force measurement process, servo motor opening / closing time test process, alarm display test process, and pressure oil pump discharge amount test process. In contrast, the draft pipe air intake valve opening measurement process 120, output opening test process 130, load test process 140, and water turbine efficiency test process 150, which will be described later, are various tests carried out from the first rotation test to the pre-use inspection, and these are collectively called wet tests. Note that the hydroelectric power plant field test process is carried out based on the hydroelectric power plant field test guidelines, and test processes that are subject to safety management review must be carried out, and test processes that are desirable to be carried out can be selected after considering the necessity for ensuring quality and the risks of omission, and test processes that can be omitted can be omitted at the discretion of the tester.

[0012] The draft pipe air intake valve opening measurement process 120 is carried out for the purpose of setting the opening of the draft pipe air intake valve 8 that does not cause turbine vibration, axial vibration, noise, etc. by changing the opening of the draft pipe air intake valve 8 with respect to a predetermined guide vane opening and measuring the turbine's operating conditions such as turbine vibration, axial vibration, noise, etc. The draft pipe air intake valve opening measurement process 120 is not a test process subject to safety management review, but is a test process that is desirable to carry out, and is actually incorporated into the on-site test processes of many hydroelectric power plants.

[0013] Here, the draft tube air inlet valve opening measuring process 120 will be described in detail with reference to Fig. 2. Fig. 2 is a schematic diagram showing an example of the positional relationship between the measuring means and the Francis turbine 50 when performing the draft tube air inlet valve opening measuring process 120. As shown in Fig. 2, in the draft tube air inlet valve opening measuring process 120, a vibration meter 121, an axial vibration sensor 122, and a sound level meter 123 are used as the measuring means.

[0014] The vibrometer 121 is attached to, for example, the upper cover of the casing 3 or the bearing stand 9 , and measures the vibration of the upper cover of the casing 3 or the bearing stand 9 .

[0015] The shaft runout sensor 122 is attached to, for example, the water turbine shaft 5 and measures the shaft runout of the water turbine shaft 5 .

[0016] The sound level meter 123 is provided, for example, away from the draft tube, and measures the noise of the draft tube 6. When the sound level meter 123 measures the noise, it also records the changes and state of the noise.

[0017] As an example of a specific measurement method of the draft tube air intake valve opening measurement process 120, the opening of the guide vane is changed from the no-load opening to the full-load opening at 10% intervals, and the opening of the draft tube air intake valve 8 is changed from fully closed to fully open at each guide vane opening. At each opening of the draft tube air intake valve 8, vibration measurement is performed by a vibration meter 121, axial vibration measurement is performed by an axial vibration sensor 122, and noise measurement is performed by a sound level meter 123. Based on the results of these measurements of the operating state of the turbine, the opening of the draft tube air intake valve 8 for each guide vane opening is set qualitatively. Note that, in the draft tube air intake valve opening measurement process 120 of FIG. 2, the measurement means are exemplified by vibration measurement, axial vibration measurement, and noise measurement, but are not limited thereto. For example, the measurement of the intake air volume of the draft tube air intake valve 8 and the measurement of the water level change of the draft tube 6 may be further performed. Furthermore, the above-mentioned measurements can be arbitrarily combined with the draft pipe air intake valve opening measurement process, and the combination can be omitted, replaced, or modified in various ways.

[0018] The output opening test process 130 is carried out for the purpose of determining the relationship between the output during the power generation operation of the hydroelectric turbine and the opening of the guide vanes, and verifying that the relationship is appropriate and that stable operation is possible within the specified possible output range. Although the output opening test process 130 is not a test process subject to safety management review, it is a test process that is desirable to carry out, and is actually incorporated into the on-site test process of many hydroelectric power plants.

[0019] The load test process 140 is carried out to operate the turbine while maintaining the turbine rotation speed, voltage, load, and power factor at rated values, and to check that there are no abnormalities such as vibration, shaft runout, oil leakage, water leakage, abnormal noise, or abnormal odor in each part of the turbine during continuous operation. The load test process 140 is a test process that is subject to safety management review, and is incorporated into the hydroelectric power plant on-site test process.

[0020] The hydraulic turbine efficiency test process 150 is carried out for the purpose of measuring the efficiency of the final hydraulic turbine. The hydraulic turbine efficiency test process 150 is not a test process that is subject to the safety management review, and is not a test process that is desirable to carry out, so it can be omitted.

[0021] The turbine efficiency testing process 150 will now be described in detail with reference to Fig. 3. Fig. 3 is a schematic diagram showing an example of the positional relationship between the measurement means and the Francis turbine 50 when carrying out the turbine efficiency testing process 150 using the ultrasonic method. As shown in Fig. 3, in the turbine efficiency testing process 150 using the ultrasonic method, an ultrasonic flowmeter 151, a pressure gauge 152, a water temperature gauge 153, and a water level gauge 154 are used as the measurement means.

[0022] The ultrasonic flowmeter 151 is attached to, for example, the penstock 1 and measures the average flow velocity of water flowing through the penstock 1 on an ultrasonic path.

[0023] The pressure gauge 152 is attached to the casing inlet short pipe 10, for example, between the downstream side of the inlet valve 2 and the upstream side of the inlet of the casing 3, and measures the water pressure (turbine inlet hydrostatic pressure) near the turbine inlet.

[0024] The water temperature gauge 153 is attached to the casing inlet short pipe 10, for example, between the downstream side of the inlet valve 2 and the upstream side of the inlet of the casing 3, and measures the water temperature.

[0025] The water level gauge 154 is attached, for example, near the turbine outlet of the draft pipe 6, and measures a vertical distance 154c from a measurement reference position 154a to a water surface 154b near the turbine outlet.

[0026] In a turbine efficiency test using the ultrasonic method, the average flow velocity measured by the ultrasonic flowmeter 151 is the average flow velocity of the ultrasonic flow path, so the flow velocity coefficient is used to calculate the average flow velocity of the measured cross section, and then this is integrated by the cross-sectional area (design value) of the measured cross section to calculate the effective flow rate in the penstock. Next, the effective head is calculated from the turbine inlet hydrostatic pressure measured by the pressure gauge 152 and the vertical distance 154c measured by the water level gauge 154. Next, the water density is calculated from the water temperature measured by the water temperature gauge 153. The turbine efficiency is calculated from the effective flow rate, effective head, and water density calculated by the above-mentioned methods, as well as the generator output measured by a wattmeter (not shown) and the generator efficiency (design value or generator efficiency test result).

[0027] In the water turbine efficiency testing process 150, an ultrasonic method is used as an example of the water turbine efficiency testing process, but the water turbine efficiency testing process only needs to measure the efficiency of the water turbine, and for example, the efficiency of the water turbine may be measured by a pressure time method that measures the change in water pressure when the guide vanes are opened and closed. Furthermore, the measurement of the efficiency of the water turbine is not limited to the measurement of the efficiency of the water turbine, and the relative efficiency of the water turbine may be measured by a differential pressure method that measures the differential pressure between side pressure holes provided on the inner and outer peripheries of the casing 3. Furthermore, the above-mentioned methods can be arbitrarily combined with the water turbine efficiency testing process, and the combination can be variously omitted, replaced, or changed.

[0028] (Embodiment) The hydroelectric power plant field test process 200 of the embodiment will be described with reference to FIG. 4. FIG. 4 is a flowchart showing an example of the hydroelectric power plant field test process 200 of the embodiment. FIG. 4(a) is a flowchart showing an example of the hydroelectric power plant field test process 200 in the case where the measurement of the operation state of the water turbine in the draft tube air inlet valve opening measurement process 120 and the calculation of the water turbine efficiency in the water turbine efficiency test process 250 are performed in parallel. FIG. 4(b) is a flowchart showing an example of the hydroelectric power plant field test process 200 in the case where the water turbine efficiency test process 250 is performed following the draft tube air inlet valve opening measurement process 120. As shown in FIG. 4(a) or (b), the hydroelectric power plant field test process 200 of the embodiment includes a waterless test process 110, a draft tube air inlet valve opening measurement process 120, a water turbine efficiency test process 250, an output opening test process 130, and a load test process 140. That is, the hydroelectric power plant on-site testing process 200 of this embodiment differs from the conventional hydroelectric power plant on-site testing process 100 in that the turbine efficiency testing process 250 is performed in conjunction with the draft pipe air inlet valve opening measurement process 120. Performing the turbine efficiency testing process 250 in conjunction with the draft pipe air inlet valve opening measurement process 120 here includes cases where the measurement of the turbine operating state in the draft pipe air inlet valve opening measurement process 120 and the calculation of the turbine efficiency in the turbine efficiency testing process 250 are performed in parallel (as shown in FIG. 4(a)), and cases where the turbine efficiency testing process 250 is performed following the draft pipe air inlet valve opening measurement process 120 (as shown in FIG. 4(b)). Furthermore, the term "measurement of the turbine operating state in the draft pipe air inlet valve opening measurement step 120 and calculation of the turbine efficiency in the turbine efficiency test step 250 are carried out in parallel" refers to cases where the measurement results of the turbine operating state in the draft pipe air inlet valve opening measurement step 120 and the calculation results of the turbine efficiency in the turbine efficiency test step 250 can be obtained simultaneously or with a time lag. Furthermore, the present invention is not limited to these, so long as a similar effect is achieved.

[0029] The turbine efficiency test process 250 is carried out in conjunction with the draft tube air intake valve opening measurement process 120, for the purpose of adding the turbine efficiency to the decision factors for setting the opening of the draft tube air intake valve 8 at a predetermined guide vane opening. Specifically, in the draft tube air intake valve opening measurement process 120, the guide vane opening is changed from the no-load opening to the full-load opening at 10% intervals, and the opening of the draft tube air intake valve 8 is changed from fully closed to fully open at each guide vane opening. At each opening of the draft tube air intake valve 8, the vibration is measured by the vibration meter 121, the shaft vibration is measured by the shaft vibration sensor 122, and the noise is measured by the sound level meter 123. In conjunction with this draft tube air intake valve opening measurement process 120, the turbine efficiency test process 250 carries out a test process using, for example, a method similar to the ultrasonic method in the above-mentioned turbine efficiency test process 150, and the turbine efficiency at each opening of the draft tube air intake valve 8 is calculated. Based on the measurement results of the operating state of the turbine and the calculation results of the turbine efficiency, the opening degree of the draft pipe air intake valve 8 relative to the opening degree of each guide vane is quantitatively set.

[0030] In the conventional hydroelectric power plant on-site test process 100, the turbine efficiency test process 150 is a test process that can be omitted from the hydroelectric power plant on-site test process 100 according to the hydroelectric power plant on-site test guidelines. Therefore, the turbine efficiency test process 150 is not considered to be a priority due to the time and effort required for preparation, and the test is often omitted or postponed. In the draft tube air intake valve opening measurement process 120, which is performed as a separate process, the opening of the draft tube air intake valve 8 at a specified guide vane opening is set qualitatively based on the measurement results of the turbine vibration, shaft runout, and noise. This makes it difficult to optimize both the opening of the draft tube air intake valve 8 and the turbine efficiency to realize efficient operation of the hydroelectric power plant.

[0031] In contrast, in the hydroelectric power plant field test process 200 of the present embodiment described above, the draft tube air intake valve opening measurement process 120 and the water turbine efficiency test process 250 are performed together, so that the time required for at least the two processes can be shortened compared to performing the draft tube air intake valve opening measurement process 120 and the water turbine efficiency test process 150 separately. Furthermore, by performing the water turbine efficiency test process 250 together with the draft tube air intake valve opening measurement process 120, the opening of the draft tube air intake valve 8 at a predetermined guide vane opening can be quantitatively set from the measurement results of the operating state of the water turbine, such as the vibration, shaft vibration, and noise of the water turbine, and the calculation results of the water turbine efficiency. As a result, it is possible to eliminate the actual situation in which the implementation of the water turbine efficiency test process 150 must be omitted or postponed due to the effort and time required for preparation, and it is possible to optimize both the opening of the draft tube air intake valve 8 and the water turbine efficiency.

[0032] Although some embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their modifications are included in the scope and spirit of the invention, and are included in the scope of the invention and its equivalents described in the claims. [Explanation of symbols]

[0033] 1... hydraulic steel pipe, 2... inlet valve, 3... casing, 4... runner, 5... turbine shaft, 6... draft pipe, 7... draft pipe air intake piping, 8... draft pipe air intake valve, 9... bearing stand, 10... casing inlet short pipe, 50... Francis turbine, 100... hydroelectric power plant field test process, 110... waterless test process, 120... draft pipe air intake valve opening measurement process, 121... vibration meter, 122... shaft runout sensor, 123... sound level meter, 130... output opening test process, 140... load test process, 150... turbine efficiency test process, 151... ultrasonic meter, 152... pressure meter, 153... water temperature meter, 154... water level meter, 154a... measurement reference position, 154b... water surface, 154c... vertical distance, 200... hydroelectric power plant field test process, 250... turbine efficiency test process

Claims

1. a draft pipe intake valve opening measurement step for setting an opening of the draft pipe intake valve for a predetermined guide vane opening; a water turbine efficiency testing step of calculating a water turbine efficiency at an opening degree of the draft tube air inlet valve, the water turbine efficiency testing step being carried out together with the draft tube air inlet valve opening degree measuring step; A method for setting the opening of a draft pipe air intake valve, comprising:

2. In the draft pipe air intake valve opening measuring step, an operating state of the water turbine is measured by a measuring means capable of measuring the operating state of the water turbine, In the water turbine efficiency testing step, the water turbine efficiency is calculated by a measuring means capable of calculating the water turbine efficiency, 2. A method for setting an opening degree of a draft pipe air intake valve according to claim 1, further comprising the step of setting the opening degree of the draft pipe air intake valve based on the measurement results of the operating state and the calculation results of the turbine efficiency.

3. 3. The method for setting the opening of a draft pipe air intake valve according to claim 2, wherein the operating condition is turbine vibration, shaft runout, noise, or a combination thereof.

4. 4. The method for setting the opening of a draft pipe air intake valve according to claim 2 or 3, wherein the hydraulic turbine efficiency is calculated by an ultrasonic method, a pressure time method, a differential pressure method, or a combination thereof.

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