Hierarchical control vacuum system and transformer oil supplementing system

Abstract

The embodiment of the utility model discloses a hierarchical control vacuum system and a transformer oil supplementing system, the system comprises an evacuation pipeline communicated with a transformer, two or more vacuum pumps communicated with the evacuation pipeline, two or more roots pumps positioned between the vacuum pumps and the transformer, and a vacuum pump communicated with the evacuation pipeline. The vacuum pump is matched with the roots pump to pump out the transformer, the pumping speed measuring device is communicated with the pumping pipeline and is used for measuring the pumping speed in the pumping pipeline, and the controller is electrically connected with the pumping speed measuring device and the roots pump and is used for receiving pumping speed data sent by the pumping speed measuring device. And when the pumping speed data is smaller than or equal to a preset pumping speed threshold value, part of the roots pumps and part of the vacuum pumps are controlled to be closed, and at least one vacuum pump and at least one roots pump are maintained to be vacuumized for a long time. The system can effectively reduce the energy consumption of long-time evacuation of the transformer.

Description

Technical Field

[0001] This utility model belongs to the field of transformer technology, specifically relating to a graded control vacuum system and a transformer oil replenishment system. Background Technology

[0002] In the transformer industry, due to product structure requirements, the vacuuming and dehydration measures after the transformer absorbs moisture after being assembled from the furnace are extremely important. All high-voltage and high-capacity products need to be evacuated to a full vacuum of 133Pa or below and maintained for a relatively long time in order to meet normal insulation and electrical performance requirements.

[0003] Currently, when evacuating transformers, the vacuum pumps used require a long evacuation time. Each vacuum pump consumes a lot of energy, and since there are many vacuum pumps, the energy consumption is even greater. Utility Model Content

[0004] The technical problem to be solved by this utility model is to address the above-mentioned deficiencies in the existing technology by providing a graded control vacuum system and a transformer oil replenishment system. This graded control vacuum system can effectively reduce the energy consumption of long-term evacuation of transformers.

[0005] According to an embodiment of the first aspect of this utility model, a graded control vacuum system is provided, comprising: a evacuation pipeline, a vacuum pump, a Roots pump, a pumping speed measuring device, and a controller; the evacuation pipeline is connected to a transformer; the number of vacuum pumps is two or more, and the vacuum pumps are connected to the evacuation pipeline; the number of Roots pumps is two or more, and the Roots pumps are located between the vacuum pumps and the transformer, and are sequentially connected to the evacuation pipeline; the vacuum pumps and the Roots pumps cooperate to evacuate the transformer; the pumping speed measuring device is connected to the evacuation pipeline and is used to measure the pumping speed within the evacuation pipeline; the controller is electrically connected to the pumping speed measuring device and the Roots pumps respectively, and is used to receive the pumping speed data sent by the pumping speed measuring device, and when the pumping speed data is less than or equal to a preset pumping speed threshold, control some of the Roots pumps and some of the vacuum pumps to shut down, and maintain at least one vacuum pump and at least one Roots pump for long-term evacuation.

[0006] In this embodiment of the invention, the vacuum pumps and Roots pumps of the graded control vacuum system work together to evacuate the transformer. As the vacuum level increases, the pumping speed naturally decreases. Therefore, in the initial stage of evacuation, more pumps are needed to maintain the pumping speed; however, as evacuation continues and the vacuum level increases, only a small number of pumps need to continue operating to meet the evacuation requirements. This system monitors the pumping speed in the evacuation pipeline in real time through a pumping speed measuring device. Then, based on the pumping speed data from the pumping speed measuring device, the controller dynamically adjusts the pump group's operating status. Specifically, when the pumping speed is lower than a preset threshold, redundant Roots pumps and some vacuum pumps are shut down, while at least one vacuum pump and at least one Roots pump are maintained for long-term evacuation. In other words, as the vacuum level increases and the pumping speed naturally decreases, the controller gradually cuts off unnecessary downstream Roots pumps and redundant vacuum pumps according to the pumping speed threshold, retaining only the minimum pump group combination that meets the current pumping speed requirements. This avoids high-power equipment from continuously operating under inefficient conditions, thereby effectively reducing the energy consumption of long-term transformer evacuation.

[0007] Optionally, the evacuation pipeline is provided with a main passage and evacuation branches. There are multiple evacuation branches, which are connected in parallel and all connected to the main passage. The number of evacuation branches is the same as the number of vacuum pumps, and each parallel branch is equipped with a vacuum pump.

[0008] Optionally, the evacuation pipeline also includes a first control valve. The number of first control valves is the same as the number of evacuation branches. Each evacuation branch is provided with a first control valve. The first control valve is connected to the gas inlet end of the vacuum pump. The controller is electrically connected to the first control valve and is used to control part of the vacuum pump to shut down when the pumping speed data is less than or equal to a preset pumping speed threshold, and to control the corresponding first control valve to close, thereby shutting down the corresponding evacuation branch.

[0009] Optionally, two or more Roots pumps may be connected in series in the main passage.

[0010] Optionally, the Roots pump includes a primary Roots pump and a secondary Roots pump. There is one primary Roots pump and at least one secondary Roots pump. The evacuation pipeline also includes bypass branches, the number of which is equal to the number of secondary Roots pumps. Each bypass branch is connected in parallel to one secondary Roots pump, and both ends of the bypass branch are connected to the inlet and outlet of the secondary Roots pump, respectively. Each bypass branch is equipped with a second control valve.

[0011] Optionally, the controller is also electrically connected to the second control valve to control the second control valve to open when the pumping speed data is less than or equal to a preset pumping speed threshold, thereby enabling the corresponding bypass branch to be connected.

[0012] Optionally, the graded control vacuum system also includes a vacuum probe connected to the evacuation pipeline. The vacuum probe is used to measure the vacuum level in the evacuation pipeline. The controller is electrically connected to the vacuum probe and is used to receive the vacuum level data emitted by the vacuum probe. The controller is also used to control the start of each vacuum pump and each Roots pump according to the vacuum level data and the preset vacuum level allowable start value.

[0013] Optionally, the vacuum pump is set to a first permissible start value, the first-stage Roots pump to a second permissible start value, and the secondary Roots pump to a third permissible start value, with the first, second, and third permissible start values ​​decreasing sequentially. The controller is used to start the vacuum pump when the vacuum level data is less than or equal to the first permissible start value, start the first-stage Roots pump when the vacuum level data is less than or equal to the second permissible start value, and start the secondary Roots pump when the vacuum level data is less than or equal to the third permissible start value.

[0014] Optionally, the graded control vacuum system also includes a transition tank located between the evacuation pipeline and the transformer, with the evacuation pipeline connected to the transformer via the transition tank.

[0015] According to a second aspect of the present invention, a transformer oil replenishment system is provided, comprising: an oil replenishment device and the aforementioned graded control vacuum system. The controller of the graded control vacuum system is electrically connected to the oil replenishment device and is used to control a portion of the Roots pump and a portion of the vacuum pump to shut down when the pumping speed data is less than or equal to a preset pumping speed threshold, thereby maintaining at least one vacuum pump and at least one Roots pump to perform long-term evacuation, and sending a start signal to the oil replenishment device. The oil replenishment device is used to replenish oil to the transformer according to the start signal. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the structure of a graded control vacuum system in some embodiments of this utility model.

[0017] In the diagram: 1. Evacuation pipeline; 11. Main passage; 12. Evacuation branch; 13. Bypass branch; 14. Airflow direction; 2. Vacuum pump; 21. First vacuum pump; 22. Second vacuum pump; 3. Roots pump; 31. First-stage Roots pump; 32. Secondary Roots pump; 4. First control valve; 41. First branch valve; 42. Second branch valve; 5. Second control valve; 6. First main passage valve; 7. Second main passage valve; 8. Vacuum gauge; 9. Pumping speed measuring device; 10. Transition tank; 110. Transformer. Detailed Implementation

[0018] The technical solutions of this utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some, not all, of the embodiments of this utility model. All other embodiments obtained by those skilled in the art based on the embodiments of this utility model without creative effort are within the scope of this utility model.

[0019] In the description of the embodiments of this utility model, it should be noted that the terms "upper", "lower", "upstream", "downstream", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings. They are only for the convenience and simplification of the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the embodiments of this utility model.

[0020] In the description of the embodiments of this utility model, the terms "first", "second", and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0021] In the description of the embodiments of this utility model, it should be noted that, unless otherwise explicitly specified and limited, the terms "connection," "setting," "installation," "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in the embodiments of this utility model according to the specific circumstances.

[0022] First, it should be noted that in this application, vacuum level refers to the absolute pressure value of the vacuum system; the smaller the value, the higher the vacuum level (i.e., closer to an absolute vacuum state). Pumping speed refers to the volume of gas removed from the evacuated container by the vacuum pump per unit time, measured in m³ / h. Since gas density decreases as vacuum level increases (pressure decreases), pumping speed exhibits a natural decay characteristic.

[0023] It should also be noted that in the transformer industry, due to product structure requirements, the evacuation and dehydration measures after transformer assembly and moisture absorption are extremely important. All high-voltage, high-capacity products need to be evacuated to a full vacuum of 133 Pa or below and maintained for a considerable period of time to meet normal insulation and electrical performance requirements. However, this prolonged evacuation process consumes a significant amount of time for the vacuum equipment. Since the vacuum pumps used are typically composed of two or more stages, resulting in a large number of pumps, the continuous operation of these high-power pumps throughout the evacuation process inevitably leads to substantial energy consumption and equipment wear, increasing unnecessary waste. Therefore, it is necessary to analyze, study, and improve the working characteristics and structural features of the vacuum pumps, pumping speed, vacuum level, and their interrelationships during the transformer vacuum process to solve and improve the aforementioned issues.

[0024] To address the unreasonableness and unnecessaryness of requiring all vacuum pumps in the existing vacuum system to operate continuously during long-term full vacuum evacuation, technical enhancements, structural adjustments, and control improvements are made to ensure that the system can meet the working characteristics of each vacuum pump stage, as well as the evacuation requirements and quality requirements, while achieving the most economical operating conditions.

[0025] This application proposes a graded vacuum control system, which is applicable to various scenarios requiring long-term evacuation, especially in the field of transformer manufacturing technology; more specifically, it is applicable to large transformers that require full vacuum for vacuum oil injection.

[0026] Example 1

[0027] Please see Figure 1 This utility model discloses a graded control vacuum system, which is mainly used in transformer systems. It includes: evacuation pipeline 1, vacuum pump 2, Roots pump 3, pumping speed measuring device 9, and controller.

[0028] The evacuation pipeline 1 is connected to the transformer 110. Two or more vacuum pumps 2 are connected to the evacuation pipeline 1. Two or more Roots pumps 3 are located between the vacuum pumps 2 and the transformer 110 and are connected to the evacuation pipeline 1. The vacuum pumps 2 and Roots pumps 3 work together to evacuate the transformer 110. A pumping speed measuring device 9 is connected to the evacuation pipeline 1 and is used to measure the pumping speed within the evacuation pipeline 1. The pumping speed measuring device 9 can be an existing flow meter. A controller is electrically connected to the pumping speed measuring device 9 and the Roots pumps 3, respectively. It receives the pumping speed data from the pumping speed measuring device 9 and, when the pumping speed data is less than or equal to a preset pumping speed threshold, controls some of the Roots pumps 3 and some of the vacuum pumps 2 to shut down, while maintaining at least one vacuum pump 2 and at least one Roots pump 3 for prolonged evacuation.

[0029] First, the operating characteristics of vacuum pump 2 and Roots pump 3 need to be explained: Vacuum pump 2 can start at atmospheric pressure, while Roots pump 3 requires a pre-pump to a certain vacuum level before it can start; otherwise, it may be overloaded and damaged. Roots pump 3 is more efficient in the high vacuum stage, and vacuum pump 2 needs to work in conjunction with Roots pump 3 to meet the high vacuum evacuation requirements. Therefore, this staged vacuum control system requires the cooperation of vacuum pump 2 and Roots pump 3 to ultimately achieve a high vacuum, as the pumping speed and ultimate vacuum level of vacuum pump 2 alone cannot meet the evacuation requirements.

[0030] Furthermore, multiple vacuum pumps 2 and Roots pumps 3 are configured in the evacuation pipeline 1, and a pumping speed measuring device 9 is set up to monitor the pipeline pumping speed in real time. The controller dynamically adjusts the pump group operation status based on the pumping speed data. When the pumping speed is lower than a preset threshold, the redundant Roots pumps 3 and vacuum pumps 2 are shut down sequentially. Specifically, in the initial stage of evacuation, all vacuum pumps 2 and Roots pumps 3 operate in coordination to quickly establish a high pumping speed to shorten the initial evacuation time. As the vacuum level increases and the pumping speed naturally decreases, the controller gradually cuts off unnecessary downstream Roots pumps 3 and redundant vacuum pumps 2 according to the pumping speed threshold, retaining only the minimum pump group combination that meets the current pumping speed requirements, such as a single vacuum pump 2 and a single Roots pump 3 (first-stage Roots pump 31), thereby avoiding continuous operation of high-power equipment under inefficient conditions. This dynamic control mechanism enables the system to maintain a high vacuum while significantly reducing the operating time and energy consumption of downstream Roots pumps 3 and redundant vacuum pumps 2, ultimately achieving a comprehensive energy efficiency improvement during long-term evacuation processes.

[0031] It should also be noted that this graded vacuum control system is based on the following principle: Within the system, as the vacuum level increases, the pumping speed exhibits a natural decay characteristic. Specifically, as the vacuum level increases (the pressure within the space decreases), the gas density decreases exponentially, causing the volume of gas that can be pumped out per unit time to decrease synchronously. The relationship between the effective pumping speed Q and the theoretical pumping speed S of the pump is: Q = S × P. Clearly, in the high vacuum stage (e.g., P < 1000 Pa), the actual effective pumping speed Q will be significantly lower than the theoretical maximum value of the pump. This scheme avoids energy waste by dynamically reducing the number of redundant pumps in operation, ensuring that the system's pumping speed demand always matches the current Q value.

[0032] Furthermore, during the vacuuming process of transformer 110, through the development of a graded adaptive vacuum system, combined with the pre-set characteristics of the permissible pumping speed and vacuum level changes of each stage of the vacuum system during operation, and the participation of the control system, as transformer 110 is evacuated from atmospheric pressure to high vacuum, each time a combined pumping speed control point of vacuum pump 2 is reached, the associated vacuum pump 2 (or Roots pump 3) is automatically disconnected, and so on, until the vacuuming process under a single combination matching at the minimum pumping speed. This newly developed graded control vacuum system provides structural improvements and technological advancements for the long-term high-vacuum evacuation process of large transformer 110, while also offering an economical and long-life solution, making it extremely important and significant in the production process of transformer 110.

[0033] In this embodiment, the pumping speed threshold is 99% of the rated pumping speed of the secondary Roots pump 32, which can be adjusted appropriately (it should be determined after debugging based on the actual usage). For example, when the measured pumping speed is lower than 99% of the effective pumping speed of the secondary Roots pump 32 (for example, a rated pumping speed of 2000 m³ / h corresponds to a threshold of 1980 m³ / h), the bypass pipeline is switched to prevent misoperation caused by the measurement deviation between the displayed pumping speed and the actual pumping speed.

[0034] In summary, this graded vacuum control system monitors the pumping speed in the evacuation pipeline 1 and gradually cuts off unnecessary downstream Roots pump 3 and redundant vacuum pump 2 according to the pumping speed threshold, retaining only the minimum pump group combination that meets the current pumping speed requirements, thereby effectively reducing the energy consumption of evacuating the transformer 110 for a long time.

[0035] The graded vacuum control system in this embodiment combines the characteristics and relationship curves of pumping speed and vacuum level changes as the gas inside the transformer 110 decreases during operation. Specifically, the lower the vacuum level, the lower the pumping speed (here, lower vacuum level refers to lower gas pressure; lower gas pressure means higher vacuum level, i.e., the transformer 110 approaches a vacuum state). It also considers the vacuum requirements that vacuum pump 2 and Roots pump 3 must meet during startup and operation, and the changes measured by pumping speed measuring device 9. This is achieved through structural analysis of existing large transformer 110 evacuation systems configured with at least three stages of vacuum pumps (i.e., vacuum pump 2, primary Roots pump 31, and secondary Roots pump 32). The overall innovative technology adopted is as follows:

[0036] 1. The transformer 110 uses a graded adaptive vacuum system consisting of: vacuum pumps (two or more), primary Roots pump 31, secondary Roots pump 32 (including: secondary Roots pump 3, tertiary or multi-stage Roots pump 3), bypass pipelines and control valves, pumping speed measuring device 9, vacuum gauge 8, control cabinet, etc.

[0037] 2. Add a pumping speed measuring device 9 and a vacuum probe to the inlet of the vacuum system to meet the pumping speed and vacuum degree detection during the evacuation process of transformer 110, so as to collect relevant data and participate in control.

[0038] 3. In accordance with the evacuation requirements of the vacuum system, the backing vacuum pump should be combined by using at least two or more vacuum pumps operating in parallel. At the same time, isolation control valves should be added to the vacuum pumps to facilitate reasonable switching and economical operation during subsequent staged control.

[0039] 4. In addition to the backing vacuum pump, the second, third or more Roots vacuum pumps (i.e., Roots pumps) in the vacuum system should have a bypass pipeline and control valve structure to gradually reduce the number of vacuum pumps required during the vacuuming process, taking into account changes in vacuum level and pumping speed.

[0040] 5. When the graded control vacuum system evacuates the main body of transformer 110, under the configuration of the pre-stage vacuum pump, the first-stage Roots vacuum pump (i.e., the first-stage Roots pump), and the second-stage Roots vacuum pump (i.e., the second-stage Roots pump), during evacuation, all isolation valves of the pre-stage vacuum pump 2 are first opened, and all bypass pipelines of the subsequent Roots vacuum pumps (i.e., Roots pumps) are closed. During normal startup and evacuation, all vacuum pumps 2 are started sequentially to evacuate transformer 110. As the evacuation process continues, the vacuum level of the vacuum system decreases (the decrease in vacuum level is referred to here). The lower the gas pressure, the higher the vacuum level (i.e., the transformer 110 gets closer and closer to a vacuum state), and the lower the pumping speed. When the system pumping speed is lower than a certain effective pumping speed of the first-stage Roots pump 31, the bypass valve of the second-stage Roots pump 3 is automatically opened and the operation of the second-stage Roots pump 3 is stopped, and the inlet valve is closed. Correspondingly, the forestage vacuum pump 2 is automatically matched to the structure of vacuum pump 2 + first-stage Roots pump 31 according to the pumping speed requirements of the first-stage Roots pump 31, and then the vacuum pumping process continues to operate normally in the most economical way.

[0041] 6. The graded control vacuum system can be used directly for vacuum oil replenishment of transformer 110 and vacuuming of small space components. When needed, simply switch the program to vacuum oil replenishment mode, which will automatically close the valve at the front end of one of the two vacuum pumps 2 (the correspondence can be set in advance), open the bypass valve of the secondary Roots pump 3, and close its inlet valve. After startup, a vacuum system with only one vacuum pump 2 and one primary Roots pump 31 running can be achieved, thus meeting the needs of vacuum oil replenishment and allowing the secondary Roots pump 3 to be in a state where it does not need to participate in the work, thereby saving energy and reducing losses.

[0042] 7. Implementation of the Control Process: The above-mentioned process is set, displayed, and controlled in real time through a control system, which also has data storage and transmission functions to meet the needs of digital production. To ensure the smooth operation of the above process, a set of effective technical solutions for mutual recognition of vacuum degree and rotation speed is developed through special verification, taking into account the product structure requirements. This is mainly reflected in the following aspects.

[0043] 7.1 The correlation control of the vacuum pumps 2 at each stage during startup, operation, and shutdown with the corresponding pumping speed, vacuum level, and branch and bypass control valves. The control system is programmed and configured based on the above control process to ultimately achieve automatic operation of the graded control vacuum system and evacuation application for various transformers 110.

[0044] 7.2 Under the above conditions, establish a control system. The vacuum level, pumping speed, valves, etc., which are set in advance by the control system, can be switched in stages according to the above control process to achieve the predetermined evacuation requirements of transformer 110 and the economical operation of the vacuum system.

[0045] Please continue reading Figure 1 In some embodiments, the evacuation pipeline 1 is provided with a main passage 11 and evacuation branches 12. There are multiple evacuation branches 12, which are connected in parallel and are all connected to the main passage 11. The number of evacuation branches 12 is the same as the number of vacuum pumps 2, and each parallel branch is provided with a vacuum pump 2.

[0046] In other words, in this embodiment, multiple vacuum pumps 2 are connected in parallel on the evacuation pipeline 1. For example, Figure 1 The diagram illustrates the scenario of two vacuum pumps 2 operating in parallel. By setting up multiple parallel evacuation branches 12, the same number as the number of vacuum pumps 2, each vacuum pump 2 can be independently configured in a single branch and controlled by an isolation valve. In the initial stage of evacuation, the parallel operation of all pumps can provide a superimposed pumping speed (e.g., a pumping speed of 2000 m³ / h for dual pumps), quickly completing the high-flow-rate evacuation in the foreground. In the later stages of vacuum improvement, by closing redundant branches (e.g., keeping only a single pump running), the current low pumping speed requirement (e.g., 500 m³ / h) can be precisely matched, thus avoiding energy waste caused by inefficient operation of multiple pumps.

[0047] Furthermore, it should be noted that compared to directly using a high-speed vacuum pump 2, this system configures multiple parallel vacuum pumps 2 on the evacuation pipeline 1. The advantage is that it dynamically adapts to different pumping speed requirements, achieving efficient operation under all conditions. Specifically, vacuum pump 2 has an efficient operating range (e.g., its operating efficiency is better within 80-100% of its rated power). In the low-speed phase, if a single high-speed pump is used for frequency conversion to match the system's required pumping speed, it means the high-speed pump can only operate at idle, resulting in a significant drop in pump efficiency. However, multiple pumps operating in parallel can run at full power (e.g., a combined pumping speed of 2000 m³ / h) during high-speed demand phases (such as the initial vacuuming phase), while only a single pump (500 m³ / h) is used during low-speed phases (such as the vacuum maintenance phase), ensuring each pump always operates within its efficient load range.

[0048] In addition, the independent control characteristics of parallel branches enable the corresponding branch to be quickly isolated when a single pump fails, ensuring that the remaining pump sets continue to work, which significantly improves the reliability of system operation and the convenience of maintenance.

[0049] Furthermore, the evacuation pipeline 1 also includes a first control valve 4. The number of first control valves 4 is the same as the number of evacuation branches 12. Each evacuation branch 12 is provided with a first control valve 4. The first control valve 4 is connected to the gas inlet end of the vacuum pump 2. The controller is electrically connected to the first control valve 4 and is used to control part of the vacuum pump 2 to shut down when the pumping speed data is less than or equal to a preset pumping speed threshold, and to control the corresponding first control valve 4 to close, so that the corresponding evacuation branch 12 is shut off.

[0050] like Figure 1 As shown, by installing a first control valve 4 at the gas inlet end of the vacuum pump 2 in each evacuation branch 12 and subjecting it to a controller, this scheme achieves precise shutdown of redundant vacuum pump 2 branches. Specifically, when the pumping speed data is lower than a preset threshold, the controller simultaneously shuts down the vacuum pump 2 of the corresponding branch and the first control valve 4 installed at its gas inlet end, completely cutting off the airflow channel of that branch. This design avoids the idling loss of the vacuum pump 2 after shutdown due to the backflow of residual gas in the pipeline, and on the other hand, it prevents the shut-down branch from interfering with the flow field of the main passage 11 through physical isolation, ensuring that the remaining operating pumps are always in the high-efficiency operating range.

[0051] Please see Figure 1 In some embodiments, two or more Roots pumps 3 are connected in series on the main passage 11.

[0052] As mentioned above, vacuum pump 2 can be started at atmospheric pressure, while Roots pump 3 requires a backing pump to be pre-evacuated to a certain vacuum level before it can be started; otherwise, it may be overloaded and damaged. Roots pump 3 is more efficient in the high vacuum stage, and vacuum pump 2 needs to be used in conjunction with Roots pump 3 to meet the evacuation requirements of high vacuum.

[0053] By connecting multiple Roots pumps 3 in series on the main passage 11, this system constructs a multi-stage compression gradient pumping structure. Specifically, the front-stage Roots pump 3 pre-compresses the gas to an intermediate pressure range (e.g., 5000-1000 Pa), and the rear-stage Roots pump 3 further compresses the gas to a high vacuum target value (e.g., <133 Pa) based on the output pressure of the front-stage pump.

[0054] This series design ensures that each stage of the Roots pump 3 always operates within its efficient pressure range (e.g., the first-stage Roots pump 31 achieves 85% efficiency at 5000-1000 Pa, and the second-stage pump achieves 80% efficiency at 1000-100 Pa). Compared to the single-stage Roots pump 3 directly compressing to the ultimate vacuum (where efficiency drops sharply to below 50%), the overall system energy efficiency is improved by 30%-40%. Furthermore, the series structure reduces the load on a single pump through pressure grading (e.g., the inlet pressure of the second-stage pump drops from atmospheric pressure to 1000 Pa, reducing power consumption by 25%), while avoiding the risk of single-pump overload and significantly extending the equipment's service life.

[0055] Furthermore, the Roots pump 3 includes a primary Roots pump 31 and a secondary Roots pump 32. There is one primary Roots pump 31 and at least one secondary Roots pump 32. The evacuation pipeline 1 also includes a bypass branch 13. The number of bypass branches 13 is equal to the number of secondary Roots pumps 32, and each bypass branch 13 is connected in parallel with one secondary Roots pump 32. The two ends of the bypass branch 13 are connected to the inlet and outlet ends of the secondary Roots pump 32, respectively. Each bypass branch 13 is equipped with a second control valve 5.

[0056] It should be noted that the term "secondary Roots pump" here includes the next-second stage Roots pump (i.e., the second-stage Roots pump), the next-second stage Roots pump (i.e., the third-stage Roots pump), ..., and even the final stage Roots pump. Taking a four-stage Roots pump as an example, from the direction gradually moving away from the vacuum pump, the four stages are the first-stage Roots pump, the next-second stage Roots pump (i.e., the second-stage Roots pump), the next-second stage Roots pump (i.e., the third-stage Roots pump), and the final stage Roots pump (i.e., the fourth-stage Roots pump). For ease of description, in this embodiment, the next-second stage Roots pump, the next-second stage Roots pump, and the final stage Roots pump are collectively referred to as "secondary Roots pump."

[0057] In this embodiment, the controller is also electrically connected to the second control valve 5, and is used to control the second control valve 5 to open when the pumping speed data is less than or equal to a preset pumping speed threshold, so that the corresponding bypass branch 13 is connected.

[0058] By configuring a bypass branch 13 and a second control valve 5 for each secondary Roots pump 32, this system can achieve dynamic cut-off of the subsequent Roots pump 3 and optimization of the airflow path.

[0059] Specifically, when the pumping speed decreases below the effective operating range of the secondary Roots pump 32, the controller opens the second control valve 5 of the bypass branch 13 and shuts down the secondary Roots pump 32, allowing the airflow to bypass the pump body directly. On the one hand, this eliminates flow resistance losses after the secondary pump stops operating; on the other hand, it avoids rotor wear caused by gas backflow in the stopped pump.

[0060] Furthermore, the independent control characteristics of the bypass branch 13 ensure that during the high vacuum stage, the staged vacuum control system can still maintain a stable pumping speed through the back pump and the first-stage Roots pump 31, while completely avoiding the ineffective operation of the secondary pump in the inefficient range, thereby achieving a synergistic improvement in energy efficiency and equipment life.

[0061] In some embodiments, the graded control vacuum system further includes a vacuum probe connected to the evacuation pipeline 1. The vacuum probe is used to measure the vacuum level in the evacuation pipeline 1. The controller is electrically connected to the vacuum probe and is used to receive the vacuum level data emitted by the vacuum probe. The controller has preset permissible vacuum level start values ​​for each vacuum pump 2 and each Roots pump 3. The controller is also used to control each vacuum pump 2 and each Roots pump 3 to start sequentially according to the vacuum level data and the preset permissible vacuum level start values.

[0062] Furthermore, the vacuum degree permissible start value of vacuum pump 2 is set to a first permissible start value, the vacuum degree permissible start value of primary Roots pump 31 is set to a second permissible start value, and the vacuum degree permissible start value of secondary Roots pump 32 is set to a third permissible start value. The first permissible start value, the second permissible start value, and the third permissible start value decrease sequentially. The controller is used to start vacuum pump 2 when the vacuum degree data is less than or equal to the first permissible start value, start primary Roots pump 31 when the vacuum degree data is less than or equal to the second permissible start value, and start secondary Roots pump 32 when the vacuum degree data is less than or equal to the third permissible start value.

[0063] For example, the first permissible start-up value (vacuum pump 2) is atmospheric pressure; the second permissible start-up value (first-stage Roots pump 31) is 5000-3000 Pa; and the third permissible start-up value (secondary Roots pump 32, which may include second-stage Roots pump 3, third-stage Roots pump 3, or even multi-stage Roots pump 3) is 2000-800 Pa.

[0064] The following is the startup process of this graded control vacuum system:

[0065] First, the operating characteristics of vacuum pump 2 and Roots pump 3 need to be explained: Vacuum pump 2 can start at atmospheric pressure, while Roots pump 3 requires a pre-pump to a certain vacuum level before it can start; otherwise, it may be overloaded and damaged. Roots pump 3 is more efficient in the high vacuum stage. Vacuum pump 2 needs to work in conjunction with Roots pump 3 to meet the high vacuum evacuation requirements. In other words, vacuum pump 2 and Roots pump 3 need to work together to ultimately achieve a high vacuum; the pumping speed and ultimate vacuum of vacuum pump 2 alone cannot meet the evacuation requirements.

[0066] When this staged vacuum control system starts up, it first evacuates the system using vacuum pump 2. Once the vacuum level in the system reaches the starting requirements of Roots pump 3, each stage of Roots pump 3 is then started sequentially. In other words, the backing pump (vacuum pump 2) creates the starting conditions for Roots pump 3, and Roots pump 3 then takes over to increase the vacuum level.

[0067] In some embodiments, the graded control vacuum system further includes a transition tank 10, which is located between the evacuation pipeline 1 and the transformer 110. The evacuation pipeline 1 is connected to the transformer 110 through the transition tank 10.

[0068] By setting a transition tank 10 between the evacuation pipeline 1 and the transformer 110, airflow buffering and process optimization during the vacuuming process can be achieved. As an intermediate container, the transition tank 10 can temporarily store a large amount of rapidly discharged gas in the early stage of vacuuming, avoiding direct impact of airflow pulses on the vacuum pump set 2, reducing pump inlet pressure fluctuations, and significantly improving the operational stability of the pump set.

[0069] The following provides further explanation of this graded vacuum control system:

[0070] This graded vacuum control system is mainly used in the field of evacuating transformer 110, where the evacuation must be carried out within a full vacuum range and for a certain period of time.

[0071] This novel technology includes two or more vacuum pumps 2, a first-stage Roots pump 31, a second-stage Roots pump 3, a third-stage or multi-stage Roots pump 3, a pumping speed measuring device 9, bypass pipelines and control valves for each subsequent vacuum pump 2, isolation control valves for multiple preceding vacuum pumps 2, a vacuum gauge 8, a control system, and a data transmission system. A pumping speed detection device and a vacuum level detection device are added at the inlet of the vacuum system to continuously monitor pumping speed and vacuum level during operation. In the multi-stage vacuum system, bypass pipelines and control valves are added to the other stage vacuum pumps 2 besides the preceding vacuum pump 2 to allow for step-by-step shut-off and bypass isolation from the rear to the front when necessary for pumping speed and vacuum level. Isolation control valves are added to the branches of the multiple preceding vacuum pumps 2 in the multi-stage vacuum system to correspondingly reduce unnecessary preceding vacuum pumps 2 when pumping speed and high vacuum are achieved after the subsequent vacuum pump 2 is shut off, thus reducing unnecessary losses.

[0072] The graded control vacuum system and its application, combined with the design requirements of the evacuation rate and vacuum degree of transformer 110, rationally matches and designs the structure of the pre-stage and post-stage vacuum pumps 2 according to the requirements of graded and adaptive vacuum technology. Simultaneously, it provides setting parameters for different pumping speeds and vacuum degrees based on the optimized combination relationship of the pre-stage and post-stage vacuum pumps 2. During the evacuation process, considering the relationship curves between vacuum degree and pumping speed, as well as the combined characteristics of the pre-stage and post-stage vacuum pumps, as the evacuation process progresses, the pumping speed and vacuum degree of the vacuum system decrease. During this process, when the system pumping speed falls below a certain effective pumping speed of the final stage Roots pump 3, the bypass valve of the final stage Roots pump 3 is automatically opened, and the operation of the final stage Roots pump 3 is stopped, cutting off that path. Correspondingly, the number of matching pre-stage vacuum pumps 2 is automatically reduced according to the pumping speed requirements of the subsequent stage Roots pump 3, and so on, until the evacuation process under the single combination matching with the minimum pumping speed is reached. The entire process is automatically detected and switched without human intervention, always maintaining the most economical structure and evacuation requirements for continuous normal operation of the evacuation process.

[0073] When the graded control vacuum system is used for vacuum oil replenishment of transformer 110 and vacuuming of small space components, the vacuum oil replenishment mode can be directly adopted. It will automatically close the valve at the front end of one of the two vacuum pumps 2 (the correspondence can be set in advance), open the bypass valve of the last stage Roots pump 3, and close its inlet valve. After starting, a vacuum system with only one vacuum pump 2 and one Roots pump 3 running will be realized.

[0074] Establishment of the control program: Based on the structural characteristics and technical requirements of the adaptive graded vacuum system, the control system is programmed and set up to ultimately satisfy the adaptive matching of graded control, adaptive conversion, and vacuum transformer 110.

[0075] In summary, the system in this embodiment is mainly applicable to the technical improvement and energy efficiency control of vacuum systems used in the vacuuming process of various transformers 110. This technology is based on the corresponding changes in pumping speed and vacuum degree during the operation of the vacuum system. Combined with the existing three-stage or multi-stage vacuum matching structure of the large transformer 110 evacuation system to meet the requirements of high pumping speed and high vacuum, by adding a pumping speed measuring device 9 to the vacuum system and a bypass structure to the subsequent Roots vacuum pump (i.e., Roots pump), the vacuum system can switch the high-speed vacuum pump 2 step by step according to the real-time measured pumping speed and the effective pumping speed and vacuum degree requirements of each stage vacuum pump 2 during operation. This reduces the unnecessary investment of the subsequent Roots vacuum pump (i.e., Roots pump) in the later stage of long-term full vacuum operation, thus reducing the energy consumption and equipment wear during the long-term evacuation process.

[0076] This system solves the unnecessary situation where the original high-power two-stage Roots pump 3 always operates under high vacuum and low pumping speed conditions, effectively reducing the working time of the two-stage Roots pump 3, extending its service life, saving unnecessary energy consumption, and reducing evacuation costs.

[0077] Example 2

[0078] In this embodiment, taking the transformer 110 scenario as an example, the overall working process of the graded control vacuum system in Embodiment 1 is described:

[0079] like Figure 1 As shown, after the transformer 110 is assembled and sealed, the vacuum system needs to be connected to the evacuation port on the upper part of the transformer 110 through a hose for vacuum degassing and dehydration treatment. Depending on the structure and type of the transformer 110, the vacuum system evacuation control is as follows:

[0080] In accordance with the graded control requirements, the pumping speed, vacuum level, and evacuation time corresponding to the switching of each stage vacuum pump 2 during the evacuation process are set on the control cabinet.

[0081] First, with the power on, the first branch valve 41, the second branch valve 42, and the first main passage valve 6 are normally open, and the second control valve 5 is normally closed. Open the pipeline valves (i.e., the second main passage valve 7) connected to the transition tank 10 and the transformer 110, as well as other pipeline valves. After clicking start, the first vacuum pump 21, the second vacuum pump 22, the first-stage Roots pump 31, and the second-stage Roots pump 32 are turned on in stages according to the preset vacuum levels of each stage of the vacuum pump 2 to perform vacuuming on the transformer 110.

[0082] Here are examples of the permissible starting vacuum values ​​for each stage of vacuum pump 2: First permissible starting value (vacuum pump 2): atmospheric pressure; Second permissible starting value (first-stage Roots pump 31): 5000 Pa; Third permissible starting value (secondary Roots pump 32, which may include second-stage, third-stage, or even multi-stage Roots pump 3): 1000 Pa. In other words, vacuum pump 2 can be started at atmospheric pressure; when the vacuum level in the system (evacuation line 1) drops to 5000 Pa, the first-stage Roots pump 31 starts, working in conjunction with vacuum pump 2 to evacuate; when the vacuum level in the system drops to 1000 Pa, the secondary Roots pump 32 starts, working in conjunction with vacuum pump 2 and the first-stage Roots pump 31 to evacuate, achieving the required vacuum level for oil replenishment.

[0083] During the evacuation process, the pumping speed detection device and vacuum gauge 8 monitor the system's pumping speed and vacuum level in real time. As the pumping speed rapidly increases from low to high and then gradually decreases, the vacuum level also continuously changes from high to low. When the pumping speed measuring device 9 detects that the system pumping speed is lower than a certain effective pumping speed of the primary Roots pump 31, it automatically opens the bypass valve (i.e., the second control valve 5) of the secondary Roots pump 32, and then closes the secondary Roots pump 32 and the first main passage valve 6 at the front end. Simultaneously, the first vacuum pump 21 and the second vacuum pump 22 automatically stop according to the preset economic matching relationship with the primary Roots pump 31, and synchronously close the first branch valve 41 or the second branch valve 42 at the inlet end of the corresponding vacuum pump 2. The transformer 110 continues to be evacuated to the corresponding vacuum level and maintained for a specified time before proceeding to the next process. This achieves the goal of cutting off the secondary Roots pump 32, which has the highest power and highest value in the vacuum system, from the working state during the subsequent high vacuum and maintenance time, thereby saving energy and extending its service life.

[0084] Secondly, the high-speed vacuum system used in the existing large transformer 110 is mainly used for evacuating the large space inside the transformer body. In the vacuum oil replenishment stage after the transformer 110 is filled with oil to the top of the tank, the maximum pumping speed is not required to meet the evacuation requirements. Therefore, when using this equipment for this purpose, it is only necessary to switch the program to the vacuum oil replenishment mode, automatically close the valve at the inlet of the first vacuum pump 21 or the second vacuum pump 22 (the correspondence can be set in advance), open the bypass valve of the secondary Roots pump 32 (i.e., the second control valve 5), close the first main passage valve 6, and after the motor starts, a vacuum system with only one vacuum pump 2 and the first-stage Roots pump 31 running is realized. This satisfies the need for vacuum oil replenishment and also saves energy and reduces losses when the secondary Roots pump 32 is not working, effectively extending the life of the core vacuum pump 2.

[0085] This utility model embodiment starts from the technical, quality, cost, and advanced aspects of the manufacturing process of transformer 110. Based on the actual situation that all vacuum pumps 2 in the vacuum system are always running during the long process of evacuating transformer 110 from normal pressure to high vacuum by the existing transformer 110 vacuum pumping unit, through the test and analysis of the working characteristics, pumping speed and vacuum degree of the vacuum pump 2, and the transformation data and curves, a brand-new structural scheme and control scheme are proposed.

[0086] Moreover, this technical solution effectively avoids unnecessary waste in the existing vacuum system of transformer 110 during long-term operation and effectively increases the service life of the high-value core vacuum pump 2.

[0087] Therefore, this technology has high technical value, economic value, application value, and promotion value.

[0088] Example 3

[0089] This utility model embodiment also discloses a transformer oil replenishment system, including: oil replenishment equipment and the graded control vacuum system in embodiment 1.

[0090] The controller of the graded vacuum system, electrically connected to the oil replenishment equipment, is used to shut down part of the Roots pump 3 and part of the vacuum pump 2 when the pumping speed data is less than or equal to a preset pumping speed threshold, maintaining at least one vacuum pump 2 and at least one Roots pump 3 for a long period of evacuation, and sending a start signal to the oil replenishment equipment. The oil replenishment equipment is used to replenish oil to the transformer 110 according to the start signal.

[0091] Specifically, the high-speed vacuum system used in the existing large transformer 110 is mainly used for evacuating the large space inside the transformer body. In the vacuum oil replenishment stage after the transformer 110 is filled with oil to the top of the tank, the maximum pumping speed is not required to meet the evacuation requirements. Therefore, when using this equipment for this purpose, it is only necessary to switch the program to the vacuum oil replenishment mode, automatically close the valve at the inlet end of the first vacuum pump 21 or the second vacuum pump 22 (the correspondence can be set in advance), open the bypass valve of the secondary Roots pump 32 (i.e., the second control valve 5), close the first main passage valve 6, and after the motor starts, a vacuum system with only one vacuum pump 2 and the first-stage Roots pump 31 running is realized. This satisfies the need for vacuum oil replenishment and also achieves energy saving and loss reduction when the secondary Roots pump 32 is not working, effectively extending the life of the core vacuum pump 2.

[0092] It is understood that the above embodiments are merely exemplary implementations used to illustrate the principles of the present utility model, and the present utility model is not limited thereto. For those skilled in the art, various modifications and improvements can be made without departing from the spirit and essence of the present utility model, and these modifications and improvements are also considered to be within the protection scope of the present utility model.

Claims

1. A graded vacuum control system, characterized in that, include: Evacuation pipeline (1), vacuum pump (2), Roots pump (3), pumping speed measuring device (9) and controller; The evacuation pipeline (1) is connected to the transformer (110). The number of vacuum pumps (2) is two or more, and the vacuum pumps (2) are connected to the evacuation pipeline (1). The number of Roots pumps (3) is two or more. The Roots pumps (3) are located between the vacuum pump (2) and the transformer (110) and are connected to the evacuation pipeline (1). The vacuum pump (2) and the Roots pumps (3) cooperate to evacuate the transformer (110). The pumping speed measuring device (9) is connected to the evacuation pipeline (1) and is used to measure the pumping speed within the evacuation pipeline (1). The controller is electrically connected to the pumping speed measuring device (9) and the Roots pump (3) respectively. It is used to receive the pumping speed data sent by the pumping speed measuring device (9), and when the pumping speed data is less than or equal to a preset pumping speed threshold, it controls part of the Roots pump (3) and part of the vacuum pump (2) to shut down, and maintains at least one vacuum pump (2) and at least one Roots pump (3) to perform long-term evacuation.

2. The graded control vacuum system according to claim 1, characterized in that, The evacuation pipeline (1) is provided with a main passage (11) and evacuation branch passages (12). There are multiple evacuation branch passages (12), which are connected in parallel and are all connected to the main passage (11). The number of the evacuation branch (12) is the same as the number of the vacuum pumps (2), and each parallel branch is equipped with a vacuum pump (2).

3. The graded control vacuum system according to claim 2, characterized in that, The evacuation pipeline (1) further includes a first control valve (4), the number of which is the same as the number of the evacuation branches (12). Each evacuation branch (12) is provided with a first control valve (4), and the first control valve (4) is connected to the gas inlet end of the vacuum pump. The controller is electrically connected to the first control valve (4) and is used to control the partial vacuum pump (2) to shut down and control the corresponding first control valve (4) to shut down when the pumping speed data is less than or equal to a preset pumping speed threshold, thereby shutting down the corresponding evacuation branch (12).

4. The graded control vacuum system according to claim 2, characterized in that, Two or more of the Roots pumps (3) are connected in series to the main passage (11).

5. The graded control vacuum system according to claim 4, characterized in that, The Roots pump (3) includes a primary Roots pump (31) and a secondary Roots pump (32), wherein there is one primary Roots pump (31) and at least one secondary Roots pump (32). The evacuation pipeline (1) also includes a bypass branch (13), the number of which is equal to the number of the secondary Roots pumps (32), and each bypass branch (13) is connected in parallel with a secondary Roots pump (32). The two ends of the bypass branch (13) are respectively connected to the inlet end and the outlet end of the secondary Roots pump (32). Each of the bypass branches (13) is equipped with a second control valve (5).

6. The graded control vacuum system according to claim 5, characterized in that, The controller is also electrically connected to the second control valve (5) and is used to control the second control valve (5) to open when the pumping speed data is less than or equal to a preset pumping speed threshold, so that the corresponding bypass branch (13) is connected.

7. The graded control vacuum system according to claim 5, characterized in that, The graded control vacuum system also includes a vacuum probe, which is connected to the evacuation pipeline (1). The vacuum probe is used to measure the vacuum level inside the evacuation pipeline (1). The controller is electrically connected to the vacuum probe and is used to receive vacuum level data emitted by the vacuum probe. The controller is also used to control the start of each vacuum pump (2) and each Roots pump (3) according to the vacuum data and the preset vacuum allowable start value.

8. The graded control vacuum system according to any one of claims 1 to 7, characterized in that, The graded control vacuum system also includes a transition tank (10), which is located between the evacuation pipeline (1) and the transformer (110). The evacuation pipeline (1) is connected to the transformer (110) through the transition tank (10).

9. A transformer oil replenishment system, characterized in that, include: The oil replenishment equipment and the graded control vacuum system according to any one of claims 1 to 8 The controller of the graded vacuum system is electrically connected to the oil replenishment device. When the pumping speed data is less than or equal to a preset pumping speed threshold, it controls some of the Roots pumps (3) and some of the vacuum pumps (2) to shut down, maintains at least one vacuum pump (2) and at least one Roots pump (3) for a long time to evacuate, and sends a start signal to the oil replenishment device. The oil replenishment device is used to replenish oil to the transformer (110) according to the start signal.

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