A novel wedge-shaped temperature measurement structure for generator stator bars

Abstract

This utility model discloses a novel wedge temperature measurement structure for generator stator bars, belonging to the field of generator design and manufacturing. It includes an upper stator bar and a lower stator bar. Multiple upper-level enlarged slots are provided in the core on the side of the upper stator bar, and an upper-level wedge mechanism is installed within each upper-level enlarged slot. Each upper-level wedge mechanism contains at least one upper-level temperature measuring element. Similarly, a lower-level enlarged slot is provided in the core on the side of the lower stator bar, and a lower-level wedge mechanism is installed within each lower-level wedge mechanism. Each lower-level wedge mechanism contains at least one lower-level temperature measuring element. This utility model effectively solves the problem of inaccurate temperature monitoring due to the inability to measure the temperature of stator bars independently.

Description

Technical Field

[0001] This utility model belongs to the field of generator design and manufacturing, specifically relating to a novel wedge temperature measurement structure for generator stator bars. Background Technology

[0002] Stator bars are a key component of generators, and stator bar temperature monitoring is an important guarantee for the safe operation of generators. Existing technologies for temperature monitoring of stator bars in the slots of large steam turbine generators all employ the method of installing temperature sensing elements in the interlayer spacers between the upper and lower stator bars, simultaneously monitoring the average temperature rise of the upper and lower stator bars.

[0003] The internal fixing structure of the stator slots in large generators uses slot bottom pads, interlayer pads, wedge pads, and corrugated plates to radially press the upper and lower layers of stator bars together with slot wedges, reducing vibrations caused by electromagnetic forces generated during generator operation. Tangentially, pads are used to seal the gaps between the stator bars and the core, ensuring a good potential gradient between the stator bars and the stator core to avoid and reduce corona discharge and prevent electrolytic corrosion within the slots.

[0004] Using enlarged slots with paired wedges is a common method for securing stator bars to the sides. The stator core slots are designed axially as multiple segments of unequal width, some of which are wider than normal slots; these are called enlarged slots. Sufficient space is provided between the stator bar sides and the stator core at the enlarged slots, where paired wedges are installed to secure the stator bars.

[0005] Among the existing temperature measurement structures, Chinese Patent Application No. CN112697298A, published on April 23, 2021, entitled "A Passive Wireless Temperature Measurement System for a Hydrogen Generator Stator," discloses a system comprising several temperature measuring devices installed within the slot wedges of the hydrogen generator stator. Each temperature measuring device includes a slot wedge-shaped outer shell, a surface acoustic wave (SAW) temperature sensor placed inside the slot wedge-shaped outer shell for measuring the temperature of the hydrogen generator stator, and a temperature signal receiver. The SAW temperature sensor and the temperature signal receiver communicate wirelessly via pulses. The temperature signal receiver is connected to a monitoring system or an industrial control computer.

[0006] The aforementioned existing technology has the following problems:

[0007] 1. The temperature measuring device inside the stator slot wedge cannot measure the temperature of the upper and lower stator bars separately; it can only measure the temperature of the upper coil. The temperature rise monitoring of the lower bar will be a blind spot for the slot wedge temperature measurement. This structure cannot monitor the operation and cooling effect of the entire stator bar cooling system.

[0008] 2. For large steam turbine generators, the stator bars are cooled by water to remove heat. This can lead to the risk of bar blockage in the stator coils. When the lower bars become blocked and the temperature becomes too high, the temperature rise of the lower bars cannot be monitored by the temperature sensing element of the slot wedge because the lower bars are far from the slot wedge. This may cause the insulation of the bars to break down due to excessive temperature, resulting in a generator grounding fault. Summary of the Invention

[0009] The purpose of this invention is to overcome the aforementioned problems and propose a novel wedge-shaped temperature measurement structure for generator stator bars, which solves the problems in the prior art where the replacement of temperature measuring elements is complicated when they fail, and the temperature measuring elements cannot monitor the upper and lower layers separately.

[0010] To achieve the above objectives, the technical solution adopted by this utility model is as follows:

[0011] A novel wedge temperature measurement structure for generator stator bars is characterized by comprising an upper stator bar and a lower stator bar. The upper stator bar has multiple upper enlarged slots on its side core, each containing an upper wedge mechanism and an upper temperature measuring element. Each upper wedge mechanism contains at least one upper temperature measuring element. Similarly, the lower stator bar has multiple lower enlarged slots on its side core, each containing a lower wedge mechanism and a lower temperature measuring element. Each lower wedge mechanism contains at least one lower temperature measuring element.

[0012] An upper wedge mechanism is provided in one upper expansion groove; a lower wedge mechanism is provided in one lower expansion groove.

[0013] The upper wedge mechanism is fixed in the upper enlarged groove by wedge tightening; the lower wedge mechanism is fixed in the lower enlarged groove by wedge tightening.

[0014] The upper temperature measuring element consists of three elements, which are installed in the upper wedge mechanisms corresponding to the beginning, end, and middle of the stator bar; the lower temperature measuring element consists of three elements, which are installed in the lower wedge mechanisms corresponding to the beginning, end, and middle of the stator bar.

[0015] The upper and lower expansion slots are located on the same side of the stator bars.

[0016] The number of upper and lower expansion slots is the same.

[0017] The upper wedge mechanism includes a first upper wedge and a second upper wedge, which are fixed together. A boss is provided on the first upper wedge, and an upper temperature measuring element is embedded on the boss.

[0018] The lower wedge mechanism includes a first lower wedge and a second lower wedge, which are fixed together. A boss is provided on the first lower wedge, and a lower temperature measuring element is embedded on the boss.

[0019] The top of the first upper wedge is wedged into the bottom of the second upper wedge, and the top of the second upper wedge is wedged into the bottom of the first upper wedge to form a matching fixation; the top of the first lower wedge is wedged into the bottom of the second lower wedge, and the top of the second lower wedge is wedged into the bottom of the first lower wedge to form a matching fixation.

[0020] Both the upper and lower temperature sensing elements are equipped with temperature sensing leads. The temperature sensing leads run from the gap between the ventilation slot plates at the bottom of the corresponding first upper and lower wedges to the back of the generator core, and then are led out to connect to an external temperature monitoring device.

[0021] The advantages of using this utility model are:

[0022] Compared with existing technologies, temperature sensing elements are embedded in the upper and lower wedges, which not only enables the wedge tightening of the stator bars, but also allows for individual temperature monitoring of the upper and lower stator bars, changing the original method of monitoring the average temperature of the upper and lower stator bars.

[0023] Compared with existing technologies, if the lower coil is blocked, the wedge temperature sensor will sensitively report the temperature rise of the lower coil, promptly reminding maintenance personnel to reduce the load and ensure the safe operation of the generator.

[0024] Compared with existing technologies, setting multiple temperature sensing elements can not only effectively monitor the cooling effect of stator bars, but also monitor the uniformity of temperature rise and the operation of the cooling system.

[0025] Compared with existing technologies, the installation and replacement are convenient by wedging the wedge into the enlarged groove, and the temperature sensing element can be replaced without removing the stator bar.

[0026] Compared with existing technologies, by setting temperature measuring elements in multiple wedges, multi-point measurement is achieved for stator bars that adopt external cooling. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of the groove wedge temperature measuring structure of this utility model;

[0028] Figure 2 This is a schematic diagram of the inclined wedge of this utility model;

[0029] Figure 3 This is the front view of the present utility model.

[0030] The markings in the diagram are as follows: 1. Upper stator bar, 2. Lower stator bar, 3. Upper expansion slot, 4. Lower expansion slot, 5. Upper wedge mechanism, 6. Lower wedge mechanism, 7. Upper temperature sensing element, 8. Lower temperature sensing element, 9. Temperature sensing lead wire, 10. First upper wedge, 11. Second upper wedge, 12. First lower wedge, 13. Second lower wedge, 14. Boss. Detailed Implementation

[0031] Example 1

[0032] A novel wedge temperature measurement structure for generator stator bars includes an upper stator bar 1 and a lower stator bar 2. The upper stator bar 1 has multiple upper expansion slots 3 on its side core, each upper wedge mechanism 5 containing an upper temperature measuring element 7. Each upper wedge mechanism 5 contains at least one upper temperature measuring element 7. The lower stator bar 2 has multiple lower expansion slots 4 on its side core, each lower expansion slot 4 containing a lower wedge mechanism 6, each lower wedge mechanism 6 containing at least one lower temperature measuring element 8.

[0033] An upper wedge mechanism 5 is provided in one upper expansion groove 3; a lower wedge mechanism 6 is provided in one lower expansion groove 4.

[0034] The upper wedge mechanism 5 is fixed in the upper expansion groove 3 by wedge tightening; the lower wedge mechanism 6 is fixed in the lower expansion groove 4 by wedge tightening.

[0035] The upper temperature measuring element 7 consists of three elements, which are installed in the upper wedge mechanism 5 corresponding to the beginning, end and middle of the stator bar; the lower temperature measuring element 8 consists of three elements, which are installed in the lower wedge mechanism 6 corresponding to the beginning, end and middle of the stator bar.

[0036] The upper expansion groove 3 and the lower expansion groove 4 are located on the same side of the stator bars.

[0037] The number of upper expansion slots 3 and lower expansion slots 4 is the same.

[0038] The upper wedge mechanism 5 includes a first upper wedge 10 and a second upper wedge 11, which are fixed together. The first upper wedge 10 and the second upper wedge 11 are provided with a boss 14, and an upper temperature measuring element 7 is embedded in the boss 14 of the first upper wedge 10.

[0039] The lower wedge mechanism 6 includes a first lower wedge 12 and a second lower wedge 13, which are fixed together. A boss 14 is provided on the first lower wedge 12, and a lower temperature measuring element 8 is embedded on the boss 14 of the first lower wedge 12.

[0040] The top of the first upper wedge 10 is wedged into the bottom of the second upper wedge 11, and the top of the second upper wedge 11 is wedged into the bottom of the first upper wedge 10 to form a matching fixation; the top of the first lower wedge 12 is wedged into the bottom of the second lower wedge 13, and the top of the second lower wedge 13 is wedged into the bottom of the first lower wedge 12 to form a matching fixation.

[0041] Both the upper temperature measuring element 7 and the lower temperature measuring element 8 are provided with temperature measuring lead wires 9. The temperature measuring lead wires 9 run from the gap between the bottom ventilation slot plates of the corresponding first upper wedge 10 and the first lower wedge 12 to the back of the generator core, and then lead out to connect to the external temperature monitoring device.

[0042] like Figure 1-2 As shown, temperature sensing elements are embedded in the bosses 14 within the upper wedge mechanism 5 and the lower wedge mechanism 6. This enables the wedge tightening of the stator bars while simultaneously allowing for independent temperature monitoring of the upper and lower stator bars, changing the original method of monitoring the average temperature of the upper and lower stator bars. If the lower stator bars become blocked, the wedge temperature sensor will sensitively report the temperature rise of the lower coil, promptly alerting maintenance personnel to reduce the load and ensure the safe operation of the generator.

[0043] The number of enlarged slots on the side of the generator stator core depends on the length of the stator bars and the number of wedges needed to fix them. The upper and lower enlarged slots are connected as a whole and are continuous. Temperature sensing elements are installed on the wedge mechanisms of the enlarged slots where the stator bar temperature needs to be measured. These elements are securely fixed within the enlarged slots by two paired wedges. Temperature sensing elements are embedded in the wedge mechanisms, and the temperature sensing lead 9 on the element is led through the gap in the ventilation slot plate at the enlarged slot to the back of the generator core, and then out of the generator. During generator operation, the temperature sensing elements at the corresponding positions can dynamically monitor the temperature of the corresponding upper stator bar 1 or lower stator bar 2 online.

[0044] If the temperature sensing element is damaged and needs to be replaced, there is no need to damage the generator stator end fixing structure or remove the stator conductors; simply remove the wedge for replacement. The operation is simple and convenient, with a short replacement cycle.

[0045] Inclined wedges with temperature sensing elements can be installed in different expansion slots, enabling multi-point measurement at different positions of the stator bars that adopt external cooling, making the temperature monitoring of the stator bars more accurate and reliable.

[0046] Example 2

[0047] For generators with externally cooled stator bars and a fully exhaust ventilation structure:

[0048] When there is one temperature sensing element in both the upper stator bar 1 and the lower stator bar 2, the temperature in the middle of the upper stator bar 1 and the lower stator bar 2 is relatively the highest. The temperature sensing element is set in the middle to independently measure the temperature of the upper stator bar 1 and the lower stator bar 2.

[0049] Preferably, when there are three temperature measuring elements in both the upper stator bar 1 and the lower stator bar 2, the generator air zone of the full-exhaust ventilation structure adopts a symmetrical design, with similar temperatures at the beginning and end, and the highest temperature in the middle. The temperature measuring elements are set at the beginning, the middle, and the middle position between the beginning and the middle. The temperature in the middle of the upper stator bar 1 and the lower stator bar 2 is relatively the highest. The temperature measuring elements set in the middle measure the temperature of the upper stator bar 1 and the lower stator bar 2. The temperature measuring elements set at the beginning, end, and middle, plus the temperature measuring element set at the middle position between the beginning and the middle, can monitor the uniformity of the temperature rise of the stator bars and the operation of the stator bar cooling system.

[0050] For generators with externally cooled stator windings and a ventilation structure with air distribution zones:

[0051] Set one or more temperature sensing elements at the theoretically calculated high temperature points of the rod, according to the required number.

[0052] If the generator set has 5 hot air zones, then 5 temperature sensing elements can be installed accordingly.

[0053] According to the number of hot air zones of the generator set, a corresponding number of inclined wedges with temperature measuring elements are installed.

[0054] For stator bar water-cooled generators:

[0055] When there is one temperature sensing element in both the upper stator bar 1 and the lower stator bar 2, the temperature sensing element is positioned close to the water outlet end to independently measure the temperature of the upper stator bar 1 and the lower stator bar 2.

[0056] Preferably, when there are two temperature measuring elements in the upper stator bar 11 and the lower stator bar 2, the temperature measuring elements are set at the beginning and end. While ensuring independent temperature measurement, the temperature difference between the beginning and end temperature measuring elements can reflect the uniformity of the temperature rise of the stator bar and the cooling status of the cooling system.

[0057] Compared to existing technologies, this method embeds temperature sensing elements on the upper and lower wedges, enabling both the wedging of the stator bars and individual temperature monitoring of the upper and lower stator bars. This changes the previous method of monitoring the average temperature of the upper and lower stator bars. If the lower stator bars become blocked, the wedge temperature sensors will sensitively report the temperature rise of the lower coil, promptly alerting maintenance personnel to reduce the load and ensure the safe operation of the generator.

Claims

1. A new type of temperature measurement structure for the wedge of a generator stator bar, characterized by: The stator includes an upper stator bar (1) and a lower stator bar (2). The upper stator bar (1) has multiple upper expansion slots (3) on its side core. An upper wedge mechanism (5) is provided in the upper expansion slot (3). An upper temperature measuring element (7) is provided in the upper wedge mechanism (5). At least one upper temperature measuring element (7) is provided in one upper wedge mechanism (5). The lower stator bar (2) has multiple lower expansion slots (4) on its side core. A lower wedge mechanism (6) is provided in the lower expansion slot (4). A lower temperature measuring element (8) is provided in the lower wedge mechanism (6). At least one lower temperature measuring element (8) is provided in one lower wedge mechanism (6).

2. A temperature measuring structure for a wedge of a stator bar of a new type of generator according to claim 1, characterized in that: Two upper wedge mechanisms (5) are provided in one upper expansion groove (3); two lower wedge mechanisms (6) are provided in one lower expansion groove (4).

3. A temperature measuring structure for a wedge of a stator bar of a new type of generator according to claim 1 or 2, characterized in that: The upper wedge mechanism (5) is fixed in the upper expansion groove (3) by wedge tightening; the lower wedge mechanism (6) is fixed in the lower expansion groove (4) by wedge tightening.

4. A temperature measuring structure for a wedge of a stator bar of a new type of generator according to claim 3, characterized in that: The upper temperature measuring element (7) consists of three elements, which are installed in the upper wedge mechanism (5) corresponding to the beginning, end and middle of the stator bar; the lower temperature measuring element (8) consists of three elements, which are installed in the lower wedge mechanism (6) corresponding to the beginning, end and middle of the stator bar.

5. A temperature measuring structure for a wedge of a stator bar of a new type of generator according to claim 1 or 2 or 4, characterized in that: The upper expansion groove (3) and the lower expansion groove (4) are located on the same side of the stator bar.

6. The novel wedge temperature measuring structure for generator stator bars according to claim 5, characterized in that: The number of upper expansion grooves (3) and lower expansion grooves (4) is the same.

7. A novel wedge-shaped temperature measuring structure for generator stator bars according to claim 1, 2, 4, or 6, characterized in that: The upper wedge mechanism (5) includes a first upper wedge (10) and a second upper wedge (11), which are fixed together. A boss (14) is provided on the first upper wedge (10), and an upper temperature measuring element (7) is embedded on the boss (14) of the first upper wedge (10).

8. The novel wedge temperature measuring structure for generator stator bars according to claim 7, characterized in that: The lower wedge mechanism (6) includes a first lower wedge (12) and a second lower wedge (13), which are fixed together. A boss (14) is provided on the first lower wedge (12), and a lower temperature measuring element (8) is embedded on the boss (14) of the first lower wedge (12).

9. The novel wedge temperature measuring structure for generator stator bars according to claim 8, characterized in that: The top of the first upper wedge (10) is wedged into the bottom of the second upper wedge (11), and the top of the second upper wedge (11) is wedged into the bottom of the first upper wedge (10) to form a matching fixation; the top of the first lower wedge (12) is wedged into the bottom of the second lower wedge (13), and the top of the second lower wedge (13) is wedged into the bottom of the first lower wedge (12) to form a matching fixation.

10. A novel wedge-shaped temperature measuring structure for generator stator bars according to claim 1, 2, 4, 6, or 9, characterized in that: Both the upper temperature measuring element (7) and the lower temperature measuring element (8) are provided with temperature measuring lead wires (9). The temperature measuring lead wires (9) run from the gap between the ventilation slot plates at the bottom of the corresponding first upper wedge (10) and the first lower wedge (12) to the back of the generator core, and then lead out to connect to the external temperature monitoring device.

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