A generator shaft voltage detection device and a detection method

Abstract

The present invention provides a generator shaft voltage detection device and a detection method. The detection device includes an insulating block, a metal bracket, and a metal contact piece. The insulating block is fixedly connected to one side of the generator body; the metal bracket is detachably connected to the insulating block through a grounding terminal, and the grounding terminal is grounded through a lead wire. A guiding block for inserting an insulating guiding plate is fixedly connected to the metal bracket; the metal contact piece is detachably connected to the metal bracket through a bolt, and the lower end of the metal contact piece is attached to the upper surface of the generator large shaft, and the insulating guiding plate separates the metal contact piece from the generator large shaft. By using the detection device and detection method of this case, it does not affect the normal grounding performance of the shaft voltage during the daily process, and there is no need to add operating switches such as circuit breakers; the impact on normal grounding during the annual shaft voltage measurement work process is minimized. After the shaft voltage measurement work is completed, the shaft voltage grounding immediately returns to normal, and there will be no additional interfaces and actions on the operation and management.

Description

Technical Field

[0001] The present invention relates to the technical field of shaft voltage detection, and particularly to a generator shaft voltage detection device and a detection method. Background Art

[0002] The shaft current caused by the generator shaft voltage can lead to serious electrocorrosion of bearings, turbine worm wheels, etc. In order to cut off the path of the shaft current, insulating pads should be placed under the bearings on the excitation side of the generator, under the exciter bearings, and at each oil pipe joint of the bearings. During operation, the insulating pads may lose their function due to oil stain accumulation, damage, or aging, etc., enabling the shaft current to flow through and causing equipment damage. In order to check the insulation condition between the generator bearings and the base during operation, the shaft voltage of the generator should be measured regularly.

[0003] Grounding carbon brushes are installed on the large shaft on the turbine side of the generator. The static charges generated by the friction between the high-speed steam and the blades on the turbine side are transmitted to the generator side through the rotating shaft. By installing grounding carbon brushes on the large shaft between the turbine and the generator, the shaft current can be guided to the ground through the carbon brushes, thus avoiding the threat of electrocorrosion to the generator journal and bearing bush. The type selection of the grounding carbon brush should ensure that its allowable circumferential speed is greater than the linear speed of the rotating shaft surface. The hardness of the carbon brush material should be moderate, the pressing force should be appropriate, to ensure reliable contact between the carbon brush and the large shaft, and the carbon brush should be able to withstand the maximum discharge current. Increasing the number of carbon brush groups can improve the contact reliability.

[0004] A key issue regarding the shaft voltage as a generator condition monitoring signal is how to measure the shaft voltage, regularly evaluate the value of the shaft voltage, and ensure that the shaft voltage is at a reasonable low level. This is an important generator test item during the power station operation process.

[0005] In the past, when measuring the shaft voltage, the shaft voltage was measured at the permanent carbon brush grounding part installed for the generator. A circuit breaker switch was set at the carbon brush grounding position. When it was necessary to measure the shaft voltage, the grounding switch was disconnected, and then a voltmeter was connected through the carbon brush for measurement.

[0006] The above method has a drawback: This carbon brush part is permanently grounded, and adding a circuit breaker switch increases an operation risk to the daily operation management of the power station. During daily operation, in order to ensure that the shaft voltage is at a low potential level, it must be in a permanently grounded state. And the measurement of the shaft voltage is generally carried out several times a year. Therefore, the measurement of the shaft voltage is an operation risk point during the operation of the generator. Moreover, this type of solution requires installing a circuit breaker switch on the original grounding device, which not only has a complex manufacturing process, belongs to a technical transformation, but also requires modifying the generator operation regulations. Summary of the Invention

[0007] The present invention aims to solve at least one of the technical problems in the related technologies to a certain extent.

[0008] The object of the present invention is to provide a generator shaft voltage detection device and a detection method, which do not affect the normal grounding performance of the shaft voltage during the daily process, and do not require the addition of operating switches such as circuit breakers; the impact of the annual shaft voltage measurement work on normal grounding is minimized, and after the shaft voltage measurement work is completed, the shaft voltage grounding immediately returns to normal. It will not generate additional interfaces and actions for operation and management.

[0009] An embodiment of one aspect of the present application provides a generator shaft voltage detection device, including an insulating block, a metal bracket and a metal contact piece. The insulating block is detachably and fixedly connected to one side of the generator body facing the generator shaft to be measured; the metal bracket is detachably and fixedly connected to the insulating block through a grounding terminal, the grounding terminal is grounded through a lead wire, and a guiding block for inserting an insulating guiding plate is fixedly connected to the metal bracket; the metal contact piece is detachably connected to the metal bracket through a bolt, the lower end of the metal contact piece fits on the upper surface of the generator shaft, and the insulating guiding plate after being inserted into the guiding block is padded between the metal contact piece and the generator shaft to isolate the metal contact piece and the generator shaft.

[0010] In some embodiments, the metal contact piece has an arc-shaped structure.

[0011] In some embodiments, the metal contact piece is a flexible metal contact piece.

[0012] In some embodiments, the guiding block and the metal contact piece are respectively located on the left and right sides of the metal bracket.

[0013] In some embodiments, the guiding block is arranged on the lower side of the metal bracket, and a jack for inserting an insulating guiding plate is provided on the guiding block.

[0014] In some embodiments, the right end of the jack is inclined downward, and the right end of the insulating guiding plate after being inserted is padded between the metal contact piece and the generator shaft.

[0015] In some embodiments, the insulating guiding plate includes a plug board and a limiting board fixedly connected. The limiting board is fixed at one end of the plug board, and the width of the limiting board is greater than the width of the plug board and the width of the jack.

[0016] In some embodiments, through holes for plugging are provided on the limiting board.

[0017] In some embodiments, the insulating guiding plate is made of an insulating board or a polytetrafluoroethylene material.

[0018] An embodiment of another aspect of the present application provides a generator shaft voltage detection method, which uses the above generator shaft voltage detection device, and includes the following steps:

[0019] S1. Insert the insulating guide plate into the guide block, lift the metal contact piece away from the generator shaft, disconnect the ground connection, short-circuit the shafts on both sides of the generator and the bearings with special carbon brushes, and measure the voltage U1 at both ends of the generator shaft with a voltmeter.

[0020] S2. Withdraw the insulating guide plate, restore the contact between the metal contact piece and the generator shaft, short-circuit the generator exciter bearing and the generator shaft with a special carbon brush, and measure the voltage U2 of the exciter end shaft to the ground with a voltmeter. If the value of U2 is less than 10V and U2≈U1, it indicates that the shaft voltage of the generator meets the standard requirements.

[0021] The beneficial effects of the present invention are as follows:

[0022] 1. By using the detection device and detection method of this case, it does not affect the normal grounding performance of the shaft voltage during daily operation, and there is no need to add operation switches such as circuit breakers.

[0023] 2. The impact of the annual shaft voltage measurement work process on normal grounding is minimized. After the shaft voltage measurement work is completed, the shaft voltage grounding immediately returns to normal, and there will be no additional interfaces and actions on the operation and management.

[0024] 3. In order to improve the quality of the shaft voltage signal, the method of multi-point setting can be adopted. The detection device of this case is evenly arranged around the circumference of the generator shaft to ensure the reliability of contact.

[0025] Additional aspects and advantages of the present invention will be given in part in the following description, will become apparent in part from the following description, or will be understood through the practice of the present invention. Brief Description of the Drawings

[0026] The above-mentioned and / or additional aspects and advantages of the present invention will become apparent and easy to understand from the following description of the embodiments in conjunction with the drawings.

[0027] Wherein:

[0028] Figure 1-2 is a schematic diagram of the application state of the generator shaft voltage detection device according to the embodiment of the present invention;

[0029] Figure 3 is a schematic diagram of the structure of the generator shaft voltage detection device according to the embodiment of the present invention;

[0030] Figure 4 is a schematic diagram of the structure of the jack on the guide block;

[0031] Figure 5 is a schematic diagram of the structure of the insulating guide plate;

[0032] Figure 6 is a circuit diagram of the generator shaft voltage detection method according to the embodiment of the present invention;

[0033] Reference numerals:

[0034] 1 - Insulating block; 2 - Generator body; 3 - Metal contact piece; 4 - Generator large shaft; 5 - Grounding terminal; 6 - Metal bracket; 7 - Bolt; 8 - Guide block; 9 - Insulating guide plate; 91 - Limiting plate; 92 - Insertion plate; 93 - Through hole; 10 - Jack. Specific embodiments

[0035] Embodiments of the present invention will be described in detail below. Examples of the embodiments are shown in the drawings. The embodiments described below with reference to the drawings are exemplary and are intended to explain the present invention and should not be construed as limiting the present invention.

[0036] The generator shaft voltage detection device and detection method according to embodiments of the present invention will be described below with reference to the drawings.

[0037] As Figure 1-4 shown, an embodiment of one aspect of the present application provides a generator shaft voltage detection device, including an insulating block 1, a metal bracket 6, and a metal contact piece 3. The insulating block 1 is detachably and fixedly connected to one side of the generator body 2 facing the generator large shaft 4 to be measured through a fastening bolt; the metal bracket 6 is detachably and fixedly connected to the insulating block 1 through a grounding terminal 5. At this time, the grounding terminal 5 also functions as a bolt. The grounding terminal 5 is grounded through a lead wire. A guide block 8 for inserting the insulating guide plate 9 is fixedly connected to the metal bracket 6; the metal contact piece 3 is detachably connected to the metal bracket 6 through a bolt 7. The lower end of the metal contact piece 3 is attached to the upper surface of the generator large shaft 4. The insulating guide plate 9 after being inserted into the guide block 8 is placed between the metal contact piece 3 and the generator large shaft 4 to isolate the metal contact piece 3 and the generator large shaft 4.

[0038] In some specific embodiments, the end of the bolt 7 can also be connected to a grounding lead wire, and the bolt and the grounding terminal 5 are at the same potential.

[0039] In some specific embodiments, the metal contact piece 3 has an arc-shaped structure. The convex side of the arc-shaped structure is attached to the generator large shaft 4.

[0040] In some specific embodiments, the metal contact piece 3 is a flexible metal contact piece, such as flexible metals like iron and aluminum, so that the metal contact piece 3 can automatically fit onto the generator large shaft 4 after the insulating guide plate 9 is pulled out.

[0041] In some specific embodiments, the guide block 8 is integrally formed with the metal bracket 6, and the guide block 8 and the metal contact piece 3 are located on the left and right sides of the metal bracket 6 respectively.

[0042] In some specific embodiments, the guide block 8 is provided on the lower side of the metal bracket 6, and the guide block 8 is provided with a jack 10 for inserting the insulating guide plate 9, asFigure 4 As shown, the insulating guide plate 9 is inserted through the jack 10 and placed at the contact position between the metal contact piece 3 and the generator large shaft 4 to isolate the metal contact piece 3 from the generator large shaft 4.

[0043] In some specific embodiments, such as Figure 5 As shown, the insulating guide plate 9 includes a plug plate 92 and a limit plate 91 which are fixedly connected. The limit plate 91 is fixed at one end of the plug plate 92. The width of the limit plate 91 is greater than the width of the plug plate 92 and the width of the jack 10. The right end of the jack 10 is inclined downward. After the insulating guide plate 9 is inserted, the limit plate 91 can be stuck outside the jack 10 to prevent the insulating guide plate 9 from falling off.

[0044] In some specific embodiments, such as Figure 5 As shown, through holes 93 for plugging and unplugging are formed in the limit plate 91, and an operator can insert a finger or a rod-like tool into the through holes 93 to pull the insulating guide plate 9.

[0045] In some specific embodiments, the insulating guide plate 9 is made of an insulating material such as an insulating board or a polytetrafluoroethylene material.

[0046] In some specific embodiments, the metal contact piece 3 can also be replaced with a carbon brush, and the function is the same.

[0047] In some specific embodiments, the upper right side of the metal contact piece 3 is fixed to the metal bracket 6 by a bolt 7, and a rectangular metal gasket can also be provided at the bolt fixing position. The metal gasket can be used to provide a force for the metal contact piece 3 to fit against the generator large shaft 4.

[0048] In some specific embodiments, in order to improve the quality of the shaft voltage signal, a multi-point setting method can be adopted. The present detection device is arranged around the circumferential position of the generator large shaft 4, and multiple ones can be evenly arranged to ensure the reliability of contact.

[0049] In some specific embodiments, the present detection device can also be only arranged at the upper end of the generator large shaft 4 for easy inspection and maintenance.

[0050] The static electricity generated by the friction between the high-speed steam on the steam turbine side and the blades is transmitted to the generator side through the rotating shaft. The present detection device is installed on the large shaft between the steam turbine and the generator, and the shaft current is guided to the ground through the lead wire of the grounding terminal 5, thus avoiding the threat of electro-corrosion to the generator journal and bearing bush. The material of the metal contact piece 3 should be moderately hard and soft, and the pressing force should be appropriate to ensure the reliable contact between the metal contact piece 3 and the generator large shaft 4. The metal contact piece 3 should be able to withstand the maximum discharge current. Increasing the number of groups of the metal contact piece 3 can improve the reliability of contact.

[0051] Another embodiment of the present application provides a method for detecting the shaft voltage of a generator, which uses the above-mentioned generator shaft voltage detection device, such as Figure 6 shown, and includes the following steps:

[0052] S1. Insert the insulating guide plate 9 into the guide block 8, lift the metal contact piece 3 away from the generator shaft 4 to disconnect the ground connection, short-circuit the shafts on both sides of the generator and the bearings with special carbon brushes, and use a voltmeter PV1 to measure the voltage U1 at both ends of the generator shaft 4.

[0053] S2. Withdraw the insulating guide plate 9, restore the metal contact piece 3 to contact with the generator shaft 4, short-circuit the generator exciter end bearing and the generator shaft with a special carbon brush, and use a voltmeter PV2 to measure the voltage U2 of the exciter end shaft to the ground. If the value of U2 is less than 10V and U2≈U1, it indicates that the shaft voltage of the generator shaft 4 meets the standard requirements. After the measurement, restore to normal.

[0054] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc. indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present invention.

[0055] In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include at least one of such features. In the description of the present invention, "a plurality" means at least two, such as two, three, etc., unless otherwise specifically defined.

[0056] In the present invention, unless otherwise clearly defined and limited, the terms "installed", "connected", "connected", "fixed", etc. should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or integrated; it can be a mechanical connection, an electrical connection, or communication with each other; it can be directly connected, or indirectly connected through an intermediate medium, and can be the internal communication of two elements or the interaction relationship between two elements, unless otherwise clearly limited. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0057] In the present invention, unless otherwise clearly specified or limited, a first feature being "on" or "under" a second feature may mean that the first and second features are in direct contact, or the first and second features are indirectly in contact via an intermediate medium. Further, a first feature being "above", "over" and "on top of" a second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the horizontal height of the first feature is higher than that of the second feature. A first feature being "under", "below" and "beneath" a second feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the horizontal height of the first feature is less than that of the second feature.

[0058] In the present invention, the terms "an embodiment", "some embodiments", "example", "specific example", or "some examples", etc. mean that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, without conflicting with each other, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples.

[0059] Although the embodiments of the present invention have been shown and described above, it can be understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those of ordinary skill in the art can make changes, modifications, substitutions, and variations to the above embodiments within the scope of the present invention.

Claims

1. A generator shaft voltage detection device, characterized in that, Comprising: An insulating block, which is detachably and fixedly connected to one side of the generator body facing the generator shaft to be measured; A metal bracket, which is detachably and fixedly connected to the insulating block through a grounding terminal. The grounding terminal is grounded through a lead wire. A guiding block for inserting an insulating guiding plate is fixedly connected to the metal bracket; A metal contact piece, which is detachably connected to the metal bracket by bolts. The lower end of the metal contact piece is attached to the upper surface of the generator shaft. After the insulating guiding plate is inserted into the guiding block, it is placed between the metal contact piece and the generator shaft to isolate the metal contact piece from the generator shaft; The guiding block is arranged on the lower side of the metal bracket, and a jack for inserting the insulating guiding plate is arranged on the guiding block; The right end of the jack is arranged to incline downward, and the right end of the inserted insulating guiding plate is placed between the metal contact piece and the generator shaft; The metal contact piece has an arc-shaped structure; The metal contact piece is a flexible metal contact piece.

2. The generator shaft voltage detection device according to claim 1, characterized in that, The guiding block and the metal contact piece are respectively located on the left and right sides of the metal bracket.

3. The generator shaft voltage detection device according to claim 1, wherein, The insulating guiding plate includes a plug board and a limiting board fixedly connected. The limiting board is fixed at one end of the plug board, and the width of the limiting board is greater than the width of the plug board and the width of the jack.

4. The generator shaft voltage detection device according to claim 3, wherein, A through hole for plugging is opened on the limiting board.

5. The generator shaft voltage detection device according to claim 1, characterized in that, The insulating guiding plate is made of an insulating board or a polytetrafluoroethylene material.

6. A method for detecting the shaft voltage of a generator, characterized in that, Using the generator shaft voltage detection device according to any one of claims 1-5, comprising the following steps: S1. Insert the insulating guiding plate into the guiding block, lift the metal contact piece away from the generator shaft, disconnect the ground connection, short-circuit the shafts on both sides of the generator and the bearings with special carbon brushes, and measure the voltage U1 at both ends of the generator shaft with a voltmeter; S2. Withdraw the insulating guiding plate, the metal contact piece resumes contact with the generator shaft, short-circuit the generator exciting end bearing and the generator shaft with a special carbon brush, and measure the voltage U2 of the exciting end shaft to the ground with a voltmeter. If the value of U2 is less than 10V and U2≈U1, it indicates that the shaft voltage of the generator shaft meets the standard requirements.

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