A method for controlling a high bypass valve to realize energy saving and consumption reduction of a high-low bypass heating unit

Abstract

The application discloses a method for controlling a high bypass valve to realize energy saving and consumption reduction of a high-low bypass heat supply unit. The high-low bypass heat supply system high bypass valve hysteresis function control method is introduced, the high bypass valve opening process curve and the high bypass valve closing process curve distinguish the working conditions of the high bypass valve opening from 0 and the working conditions of the high bypass valve closing from the opening state to 0, the low bypass valve opening degree is controlled according to the heat supply, and the low bypass desuperheating water is simultaneously fed; when the low bypass valve opening degree increases, the high bypass valve opening degree is controlled according to the high bypass valve opening process curve, and the high bypass desuperheating water is simultaneously fed; when the low bypass valve opening degree decreases, the high bypass valve opening degree is controlled according to the high bypass valve closing process curve, and the high bypass desuperheating water is simultaneously fed. The method can avoid the frequent opening and closing of the high bypass valve caused by the fluctuation of the low bypass valve opening degree near the low bypass valve opening process threshold value, ensures the long-term safe operation of the high bypass valve, prolongs the service life of the high bypass valve and reduces the energy consumption of the heat supply unit system.

Description

Technical Field

[0001] This invention relates to the field of power generation technology, and in particular to a method for controlling a high-voltage bypass valve to achieve energy saving and consumption reduction in high- and low-voltage bypass heating units. Background Technology

[0002] The flexibility retrofits implemented in thermal power units have enabled them to achieve deep peak shaving capabilities. Key technologies include low-load stable combustion of boilers, low-load denitrification, zero output of low-pressure cylinders, and bypass heating. Among these, bypass heating offers advantages such as lower investment, more flexible operation, and superior thermoelectric decoupling characteristics, making it a crucial technology for thermoelectric decoupling retrofits of thermal power units. It plays a significant role in enhancing power plant heating capacity and achieving deep peak shaving.

[0003] However, bypass heating alters the original ratio of steam entering the high- and intermediate-pressure cylinders, deviating from the design value. This directly affects the unit's axial thrust. Excessive axial thrust leads to excessive thrust bearing temperature, axial displacement, and differential expansion between the high- and intermediate-pressure cylinders, impacting the safe and stable operation of the unit. A typical high- and low-pressure bypass heating system diagram is shown below. Figure 1 As shown. The existing solution to this problem is as follows: The high bypass valve flow rate and low bypass valve flow rate are obtained based on mass balance and energy balance. Then, the opening degree of the high bypass valve is controlled based on the calculated one-to-one correspondence between the two and the low bypass valve flow rate. The control strategy is to first adjust the low bypass valve opening to meet the heating demand, and then, when the low bypass valve opening reaches a "threshold," open the high bypass valve to maintain the axial thrust balance of the high and medium pressure rotors, ensuring safe operation of the unit.

[0004] A simplified diagram of a high (low) bypass system is shown below. Figure 2 As shown, F1+F2=F3; F1·H1+F2·H2=F3·H3; H1=f(P1,T1); H2=f(P2,T2); H3=f(P3,T3), where F1, P1, and T1 are the flow rate (t / h), pressure (MPa), and temperature (°C) of the bypass steam before the desuperheater; F2, P2, and T2 are the flow rate (t / h), pressure (MPa), and temperature (°C) of the desuperheating water; F3, P3, and T3 are the flow rate (t / h), pressure (MPa), and temperature (°C) of the bypass steam after the desuperheater; H1 is the enthalpy of the bypass steam before the desuperheater; H2 is the enthalpy of the desuperheating water; and H3 is the enthalpy of the bypass steam after the desuperheater. For high-pressure or low-pressure bypass: F2, P1, P2, P3, T1, T2, and T3 can be measured in real time. Then, F1 and F3 can be obtained according to the above formula. Based on the relationship between F1 of the high-pressure and low-pressure bypasses (calculated from the heat balance diagram and the axial thrust of the high-pressure and intermediate-pressure rotors), the high-pressure bypass valve is controlled to adjust the high-pressure bypass F1 to match the low-pressure bypass F1, so that the axial thrust of the high-pressure and intermediate-pressure rotors is within a safe range, ensuring the safe and stable operation of the unit.

[0005] However, the following problems arise during actual unit operation: The relationship between F1 of the high and low bypasses is calculated based on the heat balance diagram and the axial thrust of the high and medium pressure rotors. In actual operation, the high bypass steam flow rate F1 is relatively large, which ensures safe unit operation but results in poor economic efficiency. When the low bypass valve opening is low (below the "threshold"), the high bypass valve does not need to be opened, and the unit can operate within a safe range. When the low bypass valve opens to the "threshold", the high bypass valve begins to open and further increases its opening as the low bypass valve opening increases. However, if the low bypass heat supply fluctuates around the "threshold", the high bypass valve needs to be opened and closed continuously according to the control logic. This will affect the lifespan of the high bypass valve itself and is detrimental to equipment safety. Summary of the Invention

[0006] The present invention aims to at least partially solve one of the technical problems in the related art.

[0007] Therefore, embodiments of the present invention propose a method for controlling the high bypass valve to achieve energy saving and consumption reduction in high and low bypass heating units.

[0008] This invention proposes a method for controlling a high-voltage bypass valve to achieve energy saving and consumption reduction in high- and low-voltage bypass heating units, comprising the following steps:

[0009] (1) The energy-saving optimization opening curves of the high and low bypass valves of the high and low bypass heating system were obtained through simulation experiments: G=f(D), where G is the opening of the high bypass valve and D is the opening of the low bypass valve;

[0010] (2) Introduce the high bypass valve hysteresis function control method of high and low bypass heating system, and divide the energy-saving optimization opening curves of the high and low bypass valves into high bypass valve opening process curves and high bypass valve closing process curves.

[0011] (3) Control the opening of the low bypass valve according to the heating control, and simultaneously add low bypass desuperheating water. When the opening of the low bypass valve increases, control the opening of the high bypass valve according to the opening process curve of the high bypass valve, and simultaneously add high bypass desuperheating water. When the opening of the low bypass valve decreases, control the opening of the high bypass valve according to the closing process curve of the high bypass valve, and simultaneously add high bypass desuperheating water.

[0012] In some embodiments, during the closing process of the low bypass valve, when the opening degree of the low bypass valve reaches the low bypass valve closing process threshold, the high bypass valve is reduced to 0.

[0013] In some embodiments, during the opening process of the low bypass valve, when the opening degree of the low bypass valve reaches the low bypass valve opening process threshold, the opening degree of the high bypass valve increases from 0.

[0014] In some embodiments, when the low bypass valve opening is greater than the low bypass valve saturation opening, the high bypass valve opening no longer increases.

[0015] In some embodiments, the high-voltage bypass valve opening process curve and the high-voltage bypass valve closing process curve distinguish the operating condition where the high-voltage bypass valve opening degree is 0 and the operating condition where the high-voltage bypass valve opening degree is 0 from the open state.

[0016] In some embodiments, obtaining the energy-saving optimized opening curves of the high and low bypass valves in the high and low bypass heating system includes the following steps:

[0017] (1) Put the high and low bypass heating system into operation, and gradually increase the opening of the low bypass valve starting from 0 with a certain opening value interval;

[0018] (2) Stable operation under each of the low bypass valve opening conditions makes the high and low bypass heating system tend to be stable;

[0019] (3) When the low bypass valve is running under a certain opening value, the unit operation status is monitored. If the monitoring data exceeds the alarm range, the high bypass valve opening is increased. If the monitoring data does not exceed the alarm range, the high bypass valve opening is kept unchanged.

[0020] (4) Record the opening degree of the high bypass valve and the opening degree of the low bypass valve under stable operating conditions.

[0021] In some embodiments, after step (4), the method further includes: processing and analyzing the high bypass valve opening data and the low bypass valve opening data to obtain the energy-saving optimized opening curves of the high and low bypass valves.

[0022] In some embodiments, the monitoring data are the axial displacement of the high-pressure and intermediate-pressure rotor of the unit, the temperature of the thrust bearing, and the differential expansion of the high-pressure and intermediate-pressure cylinder.

[0023] In some embodiments, the stable operation time under each of the low bypass valve opening conditions is 20-60 minutes.

[0024] In some embodiments, the spacing between the opening values ​​is less than 10%.

[0025] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0026] This invention introduces a hysteresis function control method for the high bypass valve in a high-low bypass heating system. The high bypass valve opening process curve and the high bypass valve closing process curve distinguish between the operating condition where the high bypass valve opening degree is 0 and the operating condition where the high bypass valve opening degree is closed from the open state to 0. This can avoid the frequent opening and closing of the high bypass valve caused by the low bypass valve opening degree fluctuating near the low bypass valve opening process threshold, ensuring the long-term safe operation of the high bypass valve, improving the service life of the high bypass valve, and reducing the energy consumption of the heating unit system.

[0027] This invention controls the opening degree of the high-pressure bypass valve based on the opening process curve and the closing process curve of the high-pressure bypass valve. Under the premise of safe operation of the unit, reducing the flow rate of the high-pressure bypass valve can reduce the amount of main steam that does not enter the high-pressure cylinder, thereby increasing the unit's electrical power and reducing the unit's thermal energy consumption. Attached Figure Description

[0028] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the following description of the embodiments taken in conjunction with the accompanying drawings, wherein:

[0029] Figure 1 This is a typical high-low bypass heating system diagram;

[0030] Figure 2 A simplified diagram of a high (low) bypass system;

[0031] Figure 3 This is a schematic diagram of the energy-saving optimization opening curves for high and low bypass valves;

[0032] Figure 4 This is a schematic diagram of the opening process curve and the closing process curve of the high-voltage bypass valve, which are examples.

[0033] Figure 5 This is a schematic diagram of the energy-saving optimization opening curves of high and low bypass valves in one embodiment.

[0034] Figure 6 This is a schematic diagram of the high-pressure bypass valve closing process curve and the high-pressure bypass valve opening process curve of one embodiment. Detailed Implementation

[0035] Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0036] The following describes, with reference to the accompanying drawings, a method for controlling the high-voltage bypass valve to achieve energy saving and consumption reduction in high- and low-voltage bypass heating units according to an embodiment of the present invention.

[0037] The method for controlling the high-voltage bypass valve to achieve energy saving and consumption reduction in high- and low-voltage bypass heating units according to the present invention includes the following steps:

[0038] (1) The energy-saving optimization opening curves of the high and low bypass valves of the high and low bypass heating system were obtained through simulation experiments: G = f(D), where G is the opening of the high bypass valve and D is the opening of the low bypass valve.

[0039] (2) Introduce the high bypass valve hysteresis function control method of high and low bypass heating system, and divide the energy-saving optimization opening curve of high and low bypass valve into high bypass valve opening process curve and high bypass valve closing process curve;

[0040] (3) According to the heating control low bypass valve opening degree, low bypass deheating water is introduced at the same time. When the low bypass valve opening degree increases, the high bypass valve opening degree is controlled according to the high bypass valve opening process curve, and high bypass deheating water is introduced at the same time. When the low bypass valve opening degree decreases, the high bypass valve opening degree is controlled according to the high bypass valve closing process curve, and high bypass deheating water is introduced at the same time.

[0041] Step (1) involves obtaining the energy-saving optimization opening curves of the high and low bypass valves in the high and low bypass heating system through simulation experiments, including the following steps:

[0042] S1: Activate the high and low bypass heating system, and gradually increase the opening of the low bypass valve starting from 0 with a certain interval of opening value;

[0043] S2: Stable operation under each low bypass valve opening condition makes the high and low bypass heating system tend to be stable;

[0044] S3: When the low bypass valve is running under a certain opening value, the unit's operating status is monitored. If the monitored data exceeds the alarm range, the high bypass valve opening is increased. If the monitored data does not exceed the alarm range, the high bypass valve opening remains unchanged.

[0045] S4: Record the high and low bypass valve openings under stable operating conditions;

[0046] S5: Process and analyze high and low bypass valve opening data to obtain high and low bypass valve energy-saving optimization opening curves.

[0047] In step S1, the opening value interval is less than 10%. This means that the smaller the interval, the more low bypass valve opening data under stable operating conditions are obtained, resulting in more high bypass valve opening data corresponding to the low bypass valve opening data, and consequently, more reliable energy-saving optimized opening curves for the high and low bypass valves. Preferably, the opening value interval is 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, or 10%.

[0048] The stable operation time under each low bypass valve opening condition is 20-60 minutes. The purpose of stable operation for a certain period of time is to ensure that the high and low bypass heating system tends to a stable operating state, specifically, to make the temperature, pressure and flow data of the high and low bypass heating system tend to a stable state.

[0049] Under each set low bypass valve opening condition, the unit's operation is monitored. The monitored data includes the axial displacement of the intermediate and high-pressure rotors, thrust bearing temperature, and differential expansion between the intermediate and high-pressure cylinders. If these values ​​are within the turbine's design alarm range (alarm value ± δ, where δ is selected based on the actual unit operation), the high bypass valve opening remains unchanged. If the monitored data exceeds the alarm range, the high bypass valve opening is increased to ensure it remains within the turbine's design alarm range, and the high bypass valve opening under stable operating conditions is recorded. It is important to note that the increase in the high bypass valve opening should be gradual, aiming to meet safety requirements with a relatively small opening.

[0050] Processing and analyzing high and low bypass valve opening data yields energy-saving optimization opening curves for both high and low bypass valves. For example, the energy-saving optimization opening curves for high and low bypass valves are shown below. Figure 3 As shown, from Figure 3 It can be seen that when the low bypass valve opening is lower than the low bypass valve threshold, the high bypass valve opening is 0; when the low bypass valve opening is higher than the low bypass valve threshold, the high bypass valve opening gradually increases from 0.

[0051] In step (2), the high bypass valve hysteresis function control method of the high and low bypass heating system is introduced. The high bypass valve opening process curve and the high bypass valve closing process curve distinguish the working condition when the high bypass valve opening degree is 0 and the working condition when the high bypass valve opening degree is closed from the open state to 0. This can avoid the high bypass valve frequently opening and closing due to the fluctuation of the low bypass valve opening degree near the threshold D0 of the low bypass valve opening process, and ensure the long-term safe operation of the high bypass valve.

[0052] The opening and closing process curves of the high-pressure bypass valve are as follows: Figure 4 As shown, during the closing process of the low-side bypass valve, when the opening degree of the low-side bypass valve reaches the low-side bypass valve closing process threshold D0', the high-side bypass valve closes to 0; during the opening process of the low-side bypass valve, when the opening degree of the low-side bypass valve reaches the low-side bypass valve opening process threshold D0, the opening degree of the high-side bypass valve increases from 0; the low-side bypass valve opening degree is greater than the low-side bypass valve saturation opening degree D. max When the high bypass valve opening is no longer increased, the low bypass valve opening increases when the low bypass heating flow needs to be increased, and the high bypass valve opening follows the high bypass valve opening process curve. When the low bypass heating flow needs to be reduced, the low bypass valve opening decreases, and the high bypass valve opening follows the high bypass valve closing process curve.

[0053] In one specific embodiment, the high- and low-side bypass heating system is activated. Starting from 0, the low-side bypass valve opening is gradually increased to 5%, 10%, ..., 90%, 95%, and 100%, respectively. Each operating condition is maintained for 60 minutes to ensure that the system's temperature, pressure, and flow data tend to stabilize. Under each operating condition, the axial displacement of the intermediate and high-pressure rotor, thrust bearing temperature, and differential pressure of the intermediate and high-pressure cylinders are monitored. If these values ​​are within the turbine's design alarm range, the high-side bypass valve opening remains unchanged. If the monitored data exceeds the alarm range, the high-side bypass valve opening is increased to ensure it remains within the turbine's design alarm range, and the high-side bypass valve opening under stable operating conditions is recorded. It is important to note that the increase in the high-side bypass valve opening should be slow, aiming to meet safety requirements with a smaller opening as much as possible. The opening data for the low-side and high-side bypass valves are shown in Table 1.

[0054] Table 1: Opening data of low-side bypass valve and high-side bypass valve.

[0055] project Low bypass valve opening (%) High bypass valve opening (%) Operating Condition 1 5％ 0 Operating Condition 2 10％ 0 Operating Condition 3 15％ 0 Operating Condition 4 20％ 0 Operating Condition 5 25％ 0 Operating Condition 6 30％ 10％ Operating Condition 7 35％ 12.5％ Operating Condition 8 40％ 15％ Operating Condition 9 45％ 17.5％ Operating Condition 10 50％ 20％ Operating Condition 11 55％ 22.5％ Operating Condition 12 60％ 25％ Operating Condition 13 65％ 27.5％ Operating Condition 14 70％ 30％ Operating Condition 15 75％ 32.5％ Operating Condition 16 80％ 35％ Operating Condition 17 85％ 37.5％ Operating Condition 18 90％ 40％ Operating Condition 19 95％ 40％ Operating Condition 20 100％ 40％

[0056] The energy-saving optimization opening curves for high and low bypass valves are obtained from the data in Table 1, as follows: Figure 5 As shown, when the high and low bypass heating systems of the unit are put into operation, the opening of the low bypass valve is controlled according to the heating supply, and low bypass desuperheating water is simultaneously introduced. Based on the energy-saving optimization opening curves of the high and low bypass valves, the opening of the high bypass valve is automatically controlled, and high bypass desuperheating water is simultaneously introduced, enabling energy-saving operation of the high and low bypass heating systems. However, when the low bypass valve opening is low, below 25% of the low bypass valve threshold, the high bypass valve does not need to open. When the low bypass valve opens to 25% of the low bypass valve threshold, the high bypass valve begins to open, and its opening further increases as the low bypass valve opening increases. However, if the low bypass heating supply fluctuates around the low bypass valve threshold of 25%, according to the automatic control logic, the high bypass valve needs to be continuously opened and closed. This will affect the lifespan of the high bypass valve itself and is detrimental to equipment safety.

[0057] This invention, based on the energy-saving optimization opening curves of high and low bypass valves, divides these curves into a high bypass valve opening process curve and a high bypass valve closing process curve. The low bypass valve opening is controlled according to the heating supply control, while simultaneously introducing low bypass desuperheating water. When the low bypass valve opening increases, the high bypass valve opening is controlled according to the high bypass valve opening process curve, and high bypass desuperheating water is introduced simultaneously. Conversely, when the low bypass valve opening decreases, the high bypass valve opening is controlled according to the high bypass valve closing process curve, and high bypass desuperheating water is introduced simultaneously. The opening data of the high and low bypass valves during the low bypass valve opening process are shown in Table 2, and the opening data of the high and low bypass valves during the low bypass valve closing process are shown in Table 3.

[0058] Table 2: Opening degree data of low bypass valve and high bypass valve during the opening process of low bypass valve.

[0059]

[0060] Table 3: Opening data of low bypass valve and high bypass valve during the low bypass valve closing process.

[0061]

[0062] The high-pressure bypass valve closing process curve and the high-pressure bypass valve opening process curve are obtained from Tables 2 and 3, as follows: Figure 6 As shown, during the closing process of the low-side bypass valve, when the opening degree of the low-side bypass valve reaches 15% of the low-side bypass valve closing threshold, the high-side bypass valve closes to 0. During the opening process of the low-side bypass valve, when the opening degree of the low-side bypass valve reaches 25% of the low-side bypass valve opening threshold, the opening degree of the high-side bypass valve increases from 0. When the opening degree of the low-side bypass valve exceeds 90% of its saturation opening degree, the opening degree of the high-side bypass valve no longer increases. When the low-side bypass heating flow needs to increase, the low-side bypass valve opening increases, and the high-side bypass valve opening follows the high-side bypass valve opening curve. When the low-side bypass heating flow needs to decrease, the low-side bypass valve opening decreases, and the high-side bypass valve opening follows the high-side bypass valve closing curve.

[0063] A hysteresis function control method for the high-side bypass valve in a high- and low-side bypass heating system is introduced. The opening and closing process curves of the high-side bypass valve distinguish between the condition where the valve opens from 0 and the condition where it closes from open to 0. Based on the heating control, the opening of the low-side bypass valve is adjusted according to... Figure 6 The control curve shown controls the opening degree of the high bypass valve, enabling energy-saving operation of both high and low bypass heating systems. It also avoids frequent opening and closing of the high bypass valve caused by fluctuations in the low bypass valve opening degree near the threshold during the low bypass valve opening process, ensuring long-term safe operation of the high bypass valve, improving its service life, and reducing the energy consumption of the heating unit system.

[0064] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms may refer to different embodiments or examples. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0065] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0066] Although embodiments of the invention have been shown and described, those skilled in the art will understand that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the claims and their equivalents.

Claims

1. A method for controlling a high-voltage bypass valve to achieve energy saving and consumption reduction in a high- and low-voltage bypass heating unit, characterized in that, Includes the following steps: (1) The energy-saving optimization opening curves of the high and low bypass valves of the high and low bypass heating system were obtained through simulation experiments: G = f(D), where G is the opening of the high bypass valve and D is the opening of the low bypass valve. (2) Introduce the high bypass valve hysteresis function control method of high and low bypass heating system, and divide the energy-saving optimization opening curves of the high and low bypass valves into high bypass valve opening process curves and high bypass valve closing process curves. (3) Based on the heating control, the opening degree of the low bypass valve is controlled, and low bypass desuperheating water is simultaneously introduced. When the opening degree of the low bypass valve increases, the opening degree of the high bypass valve is controlled according to the opening process curve of the high bypass valve, and high bypass desuperheating water is simultaneously introduced. When the opening degree of the low bypass valve decreases, the opening degree of the high bypass valve is controlled according to the closing process curve of the high bypass valve, and high bypass desuperheating water is simultaneously introduced. Obtaining the energy-saving optimized opening curves of the high and low bypass valves in the high and low bypass heating system includes the following steps: (1) Put the high and low bypass heating system into operation, and gradually increase the opening of the low bypass valve starting from 0 with a certain opening value interval; (2) Stable operation under each of the low bypass valve opening conditions makes the high and low bypass heating system tend to be stable; (3) When the low bypass valve is running under a certain opening value, the unit operation status is monitored. If the monitoring data exceeds the alarm range, the high bypass valve opening is increased. If the monitoring data does not exceed the alarm range, the high bypass valve opening is kept unchanged. (4) Record the opening degree of the high bypass valve and the opening degree of the low bypass valve under stable operating conditions.

2. The method as described in claim 1, characterized in that, During the closing process of the low bypass valve, when the opening degree of the low bypass valve reaches the threshold of the low bypass valve closing process, the high bypass valve is reduced to 0.

3. The method as described in claim 1, characterized in that, During the opening process of the low bypass valve, when the opening degree of the low bypass valve reaches the threshold of the low bypass valve opening process, the opening degree of the high bypass valve increases from 0.

4. The method as described in claim 1, characterized in that, When the opening degree of the low bypass valve is greater than the saturation opening degree of the low bypass valve, the opening degree of the high bypass valve will no longer increase.

5. The method as described in claim 1, characterized in that, The opening process curve and the closing process curve of the high-voltage bypass valve distinguish the working condition where the opening degree of the high-voltage bypass valve is opened from 0 and the working condition where the opening degree of the high-voltage bypass valve is closed from the open state to 0.

6. The method as described in claim 1, characterized in that, After step (4), the method further includes: processing and analyzing the high bypass valve opening data and the low bypass valve opening data to obtain the energy-saving optimization opening curves of the high and low bypass valves.

7. The method as described in claim 1, characterized in that, The monitoring data includes the axial displacement of the high-pressure and intermediate-pressure rotor, the temperature of the thrust bearing, and the differential expansion of the high-pressure and intermediate-pressure cylinders.

8. The method as described in claim 1, characterized in that, The stable operating time under each of the low bypass valve opening conditions is 20-60 minutes.

9. The method as described in claim 1, characterized in that, The interval between the opening values ​​is less than 10%.

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