Method for evaluating fault risk of rotor winding of deep peak regulation steam turbine generator
By calculating the relative displacement of the rotor winding and core of the deep peak shaving turbine generator, and evaluating the fault risk, the problem of rotor winding failure risk assessment during the deep peak shaving process is solved, and timely and accurate assessment of fault risks and real-time monitoring of health status is achieved.
Patent Information
- Application Number
- CN202411689792.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-11-25
- Publication Date
- 2025-03-11
AI Technical Summary
During the deep peak shaving process, the temperature difference between the rotor winding of the turbine generator and the core leads to an increase in the relative expansion amount, increasing the risk of failure. The existing technology lacks effective fault risk assessment methods.
By obtaining the excitation current multiple of the generator, calculating the average temperature of the rotor winding and the core, further calculating the axial deformation and relative displacement, and evaluating the failure risk.
It realizes a timely and accurate assessment of the failure risk of generator rotor windings, and can monitor health status in real time, reduce unplanned downtime, and improve power generation efficiency and economy.
Smart Images
Figure CN119596141A_ABST
Abstract
Description
Technical Field
[0001] The present application belongs to the field of renewable energy power generation technology, and specifically, relates to a method for assessing the risk of rotor winding failure of a deep peak-shaving steam turbine generator. Background Art
[0002] With the continuous development of the power system, traditional coal-fired power units are more involved in flexible operation modes such as peak load regulation, voltage regulation, and frequency regulation. As an important operation mode, deep peak load regulation often exceeds the minimum stable combustion load of the power plant boiler, and has a particularly significant impact on the stator and rotor windings and cores of the generator.
[0003] During the deep peak-shaving process, the generator needs to adjust the load frequently, and the excitation current changes greatly. At this time, the heat exchange and heat balance speed between the rotor winding and the rotor core is much slower than the winding temperature change speed, so there is a significant temperature difference between the winding and the core, resulting in an increase in the relative expansion of the rotor winding and the core. Considering the mutual constraints between the materials, the rotor winding will be subject to the friction resistance of the slot insulation and the end obstruction during the expansion and contraction process, causing the rotor winding to bear internal stress. Long-term stress and friction displacement may cause rotor insulation failures, such as slot insulation wear, dislocation, and rotor winding inter-turn short circuit. These faults will not only affect the normal operation of the generator, but may also pose a threat to the stable operation of the power grid. Therefore, it is particularly important to conduct fault risk assessment on the rotor winding of deep peak-shaving steam turbine generators. Summary of the invention
[0004] The technical problem solved by the present application is: how to timely and accurately evaluate the failure risk of the rotor of a deep peak-shaving steam turbine generator.
[0005] The present application provides a method for assessing the risk of rotor winding failure of a deep peak-shaving steam turbine generator, the method comprising:
[0006] Obtain the excitation current multiple of the generator;
[0007] The average temperature of the rotor winding and the average temperature of the rotor core are calculated according to the excitation current multiple;
[0008] The axial deformation of the rotor winding is calculated according to the average temperature of the rotor winding, and the axial deformation of the rotor core is calculated according to the average temperature of the rotor core;
[0009] The relative displacement is calculated according to the axial deformation of the rotor winding and the axial deformation of the rotor core;
[0010] The failure risk of the generator rotor is evaluated according to the relative displacement.
[0011] Optionally, the method for obtaining the excitation current multiple of the generator includes:
[0012] The actual excitation current is obtained through the generator monitoring system, and the excitation current multiple is calculated according to the following formula:
[0013]
[0014] In the formula, I f Indicates the measured excitation current, I fN Indicates the rated excitation current, K f Indicates the excitation current multiple.
[0015] Optionally, the method of respectively calculating the average temperature of the rotor winding and the average temperature of the rotor core according to the excitation current multiple includes:
[0016] Based on finite element simulation and curve fitting, the relationship function between the steady-state average temperature of the generator rotor winding and the rotor core and the excitation current multiple is established, and the average temperature of the rotor winding and the average temperature of the rotor core during the operation of the generator is calculated in real time through the relationship function. The calculation formula is as follows:
[0017]
[0018] Where, T Cu is the average temperature of the rotor winding, a1, a2, a3, a4 are the fitting coefficients of the functional relationship between the average temperature of the rotor winding and the excitation current multiple, T Fe is the average temperature of the rotor core, b1, b2, b3, and b4 are the fitting coefficients of the functional relationship between the average temperature of the rotor core and the excitation current multiple.
[0019] Optionally, the calculation formula for obtaining the axial deformation of the rotor winding according to the average temperature of the rotor winding is as follows:
[0020] Δl Cu (t) = α Cu ·l Cu ·[T Cu (t)-T Cu0 ]
[0021] In the formula, Δl C u(t) is the axial deformation of the straight length of the rotor winding at time t, α Cu is the linear thermal expansion coefficient of the rotor winding material, l Cu is the original length of the straight section of the rotor winding, Tcu(t) is the average temperature of the rotor winding at time t during operation, T Cu0 is the rotor winding temperature at the initial moment.
[0022] Optionally, the calculation formula for obtaining the axial deformation of the rotor core according to the average temperature of the rotor core is as follows:
[0023] Δl Fe (t) = α Fe ·l Fe ·[T Fe (t)-T Fe0 ]
[0024] In the formula, Δl F e(t) is the axial deformation of the rotor core length at time t, α Fe is the linear thermal expansion coefficient of the rotor core material, l Fe is the original length of the rotor core, T F e(t) is the rotor core temperature at time t during operation, T Fe0 is the rotor core temperature at the initial moment.
[0025] Optionally, the calculation formula for the relative displacement is calculated according to the axial deformation of the rotor winding and the axial deformation of the rotor core as follows:
[0026]
[0027] Where Δl represents the relative displacement.
[0028] The present application provides a method for assessing the risk of rotor winding failure of a deep peak-shaving steam turbine generator, which has the following technical effects:
[0029] The cumulative value of the relative displacement between the rotor winding and the rotor core can be used to effectively assess the risk of rotor winding failure. The above fault assessment method can monitor and predict the health of the generator rotor winding in real time, detect and handle faults in a timely manner, reduce unplanned downtime, and improve power generation efficiency and economy. BRIEF DESCRIPTION OF THE DRAWINGS
[0030] Figure 1 A flow chart of main steps of a method for assessing rotor winding failure risk of a deep peak-shaving steam turbine generator according to one or more embodiments;
[0031] Figure 2 A 300MW steam turbine generator rotor temperature field simulation model according to one or more embodiments;
[0032] Figure 3 The excitation current variation of a 300MW steam turbine generator from June to August according to one or more embodiments;
[0033] Figure 4is the average temperature of the rotor winding and the rotor core at different excitation current multiples according to one or more embodiments;
[0034] Figure 5 The temperature variation of the rotor winding of a 300MW steam turbine generator from June to August according to one or more embodiments;
[0035] Figure 6 is the axial deformation of the rotor winding of a 300MW steam turbine generator from June to August according to one or more embodiments;
[0036] Figure 7 The temperature variation of the rotor core of a 300MW steam turbine generator from June to August according to one or more embodiments;
[0037] Figure 8 is the axial deformation of the rotor core of a 300MW steam turbine generator from June to August according to one or more embodiments;
[0038] Fig. 9 is the integral of the relative displacement (absolute value) between the rotor winding and the core within three months according to one or more embodiments. DETAILED DESCRIPTION
[0039] In order to make the purpose, technical solution and advantages of the present application more clearly understood, the present application is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.
[0040] Before describing in detail the various embodiments of the present application, the technical concept of the present application is first briefly described: Currently, when deep peak regulation is performed, a significant temperature difference occurs between the winding and the core, resulting in an increase in the relative expansion of the rotor winding and the core, which leads to the risk of rotor failure. At this stage, there is no effective monitoring method. To this end, the present application provides a method for assessing the risk of rotor winding failure of a deep peak-shaving steam turbine generator. According to the obtained excitation current multiples, the average temperature of the rotor winding and the average temperature of the rotor core are calculated respectively, and the axial deformation of the rotor winding and the axial deformation of the rotor core are calculated respectively according to each temperature, and the relative displacement of the two is obtained to assess the risk of rotor failure. This method can monitor the operating status of the generator rotor in a timely and accurate manner to ensure the safety of the deep peak regulation process. The specific principles of the method for assessing the risk of rotor winding failure of a deep peak-shaving steam turbine generator of the present application are described in combination with more embodiments below.
[0041] Specifically, Figure 1 As shown, the method for evaluating the rotor winding failure risk of a deep peak-shaving steam turbine generator in the first embodiment includes:
[0042] Step S10: obtaining the excitation current multiple of the generator;
[0043] Step S20: Calculate the average temperature of the rotor winding and the average temperature of the rotor core according to the excitation current multiple;
[0044] Step S30: Calculate the axial deformation of the rotor winding according to the average temperature of the rotor winding, and calculate the axial deformation of the rotor core according to the average temperature of the rotor core;
[0045] Step S40: Calculate the relative displacement according to the axial deformation of the rotor winding and the axial deformation of the rotor core;
[0046] Step S50: Evaluate the fault risk of the generator rotor according to the relative displacement.
[0047] In one or more embodiments, the method for obtaining the excitation current multiple of the generator in step S10 includes:
[0048] The actual excitation current is obtained through the generator monitoring system, and the excitation current multiple is calculated according to the following formula:
[0049]
[0050] In the formula, I f Indicates the measured excitation current, I fN Indicates the rated excitation current, K f Indicates the excitation current multiple.
[0051] In one or more embodiments, in step S20, the method of respectively calculating the average temperature of the rotor winding and the average temperature of the rotor core according to the excitation current multiple includes:
[0052] Based on finite element simulation and curve fitting, the relationship function between the steady-state average temperature of the generator rotor winding and the rotor core and the excitation current multiple is established, and the average temperature of the rotor winding and the average temperature of the rotor core during the operation of the generator is calculated in real time through this relationship function. The calculation formula is as follows:
[0053]
[0054] Where, T Cu is the average temperature of the rotor winding, a1, a2, a3, a4 are the fitting coefficients of the functional relationship between the average temperature of the rotor winding and the excitation current multiple, T Fe is the average temperature of the rotor core, b1, b2, b3, b4 are the fitting coefficients of the functional relationship between the average temperature of the rotor core and the excitation current multiple. The numerical fitting method here includes finite element simulation and curve fitting method.
[0055] Specifically, the turbine generator is usually heated by passing the excitation current through the rotor winding when it is started and rotating, causing the rotor winding and the rotor core to rise in temperature and expand. Since the winding is the main heat source, its average temperature is higher than the temperature of the core slot, and the linear expansion coefficient of copper (16.6×10 -6 m / m℃) is higher than the linear expansion coefficient of steel (12×10 -6 m / m℃), so when the motor is running with load, the rotor winding will tend to stretch more than the rotor core. Under deep peak load conditions, the load changes more frequently and the load change rate is also greater. At this time, there is a significant temperature difference between the winding and the core, and the relative displacement between the two increases further. The generator rotor winding will be subjected to greater mechanical and thermal stress, increasing the risk of failure.
[0056] In one or more embodiments, in step S30, the calculation formula for obtaining the axial deformation of the rotor winding according to the average temperature of the rotor winding is as follows:
[0057] Δl Cu (t) = α Cu ·l Cu ·[T Cu (t)-T Cu0 ]
[0058] In the formula, Δl C u(t) is the axial deformation of the straight length of the rotor winding at time t, α Cu is the linear thermal expansion coefficient of the rotor winding material, l Cu is the original length of the straight section of the rotor winding, Tcu(t) is the average temperature of the rotor winding at time t during operation, T Cu0 is the rotor winding temperature at the initial moment.
[0059] In one or more embodiments, the calculation formula for calculating the axial deformation of the rotor core according to the average temperature of the rotor core is as follows:
[0060] Δl Fe (t) = α Fe ·l Fe ·[T Fe (t)-T Fe0 ]
[0061] In the formula, Δl F e(t) is the axial deformation of the rotor core length at time t, α Fe is the linear thermal expansion coefficient of the rotor core material, l Fe is the original length of the rotor core, T F e(t) is the rotor core temperature at time t during operation, T Fe0 is the rotor core temperature at the initial moment.
[0062] In one or more embodiments, the calculation formula for the relative displacement is calculated according to the axial deformation of the rotor winding and the axial deformation of the rotor core as follows:
[0063]
[0064] In the formula, Δl represents the relative displacement. The meaning of the above formula is to determine the relative displacement between the rotor winding and the rotor core according to the deformation of the two, take its absolute value, and integrate the absolute value over time. The numerical form of the above calculation formula is as follows:
[0065]
[0066] Under deep peak load conditions, the integral value is positively correlated with the degree of rotor winding performance degradation, which can be used to effectively evaluate the risk of rotor winding failure.
[0067] In order to obtain the temperature data required for calculation, this embodiment takes a 300MW steam turbine generator as an example, selects one slot and two half pitches of the rotor in the circumferential direction, and selects the entire axial section as the research object, and obtains the average temperature of the rotor winding and the rotor core through Ansys Fluent fluid-thermal coupling simulation. The simulation model is as follows: Figure 2 The rated parameters of the steam turbine generator are shown in Table 1.
[0068] Table 1 Basic structural parameters of a 300MW steam turbine generator rotor
[0069] Basic parameters Numeric Rated capacity / MW 300 Rated excitation current / A 2642 Rated speed / (r / min) 3000 Rotor outer diameter / mm 1100 Effective length of rotor / mm 5150 Rotor winding material copper Rotor core material 45 steel
[0070] Combined with the actual operation data of the unit, the rotor winding and rotor core shape variables are calculated. The excitation current data of the unit from June to August are as follows Figure 3 As shown in the figure (sampling interval is 300s), it can be seen that when the unit participates in deep peak regulation, its excitation current changes dramatically between 0.5 and 1 times the rated value. Ignoring the influence of damping thermal effect and rotor iron loss, the rotor winding is regarded as the only heat source. After finite element simulation, the relationship between the average temperature of the generator rotor winding and rotor core and the excitation current multiple is obtained, as shown in Figure 4 As shown. It can be seen that the average temperature of the rotor winding and the rotor core increases nonlinearly with the increase of the excitation current. After curve fitting, the relationship between the two is as follows:
[0071]
[0072] Furthermore, the continuous temperature variation of the rotor winding from June to August is calculated, such as Figure 5From the average temperature variation curve of the winding, it can be seen that the lowest temperature in three months is 63.64℃ and the highest temperature is 107.90℃.
[0073] According to the average temperature of the winding from June to August, the axial deformation of the rotor winding at time t from June to August is calculated by the above formula. The results are as follows: Figure 6 As shown. Figure 6 It can be seen that since the rotor winding is the only heat source of the rotor and the linear thermal expansion coefficient of copper is large, its deformation is large, and the single maximum deformation reaches 0.00703m. The deformation curve of the rotor winding at any time t shows similarity with the change trend of the winding temperature.
[0074] Furthermore, the continuous temperature variation of the rotor core from June to August is calculated, such as Figure 7 The average temperature variation of the rotor core is smaller than that of the winding. The lowest temperature in three months is 61.90℃ and the highest temperature is 96.33℃. Based on the average temperature of the rotor core from June to August, the axial deformation corresponding to time t from June to August is calculated by the above formula. The result is as follows: Figure 8 As shown. Figure 8 It can be seen that since the core temperature change mainly comes from the heat transfer of the winding and the linear thermal expansion coefficient of steel is small, the deformation of the rotor core is relatively small, and the single maximum deformation is 0.00441m. The deformation curve of the rotor core at any time t is also similar to the change trend of its temperature.
[0075] Furthermore, according to the deformation of the rotor winding and the rotor core at time t from June to August, the cumulative relative displacement between the two is calculated using the above formula, and the result is as follows: Fig. 9 As shown. Fig. 9 It can be seen that the cumulative relative displacements of the rotor winding and the rotor core from June to August are 75.17m, 77.5m, and 106.11m respectively. The cumulative relative deformation in the three-month peak load operation is 258.78m.
[0076] Depend on Fig. 9 It can be seen that under the operating conditions of deep peak regulation, frequent temperature fluctuations will cause the rotor winding and the core to experience significant deformation. The cumulative relative displacement between the two gradually accumulates over time, which is the key factor causing the rotor winding insulation failure. It is crucial to ensure that the relative displacement between the rotor winding and the core remains within the specified normal operating range. Considering that the relative displacement between the generator rotor winding and the core accumulates over time, and for generators of different capacities, the temperature rise of the two during operation is different, the normal threshold of the integral can be formulated according to the specific situation. When this threshold is exceeded, it can be considered that the rotor winding has reached a certain degree of deterioration and has a greater risk of failure, which requires key monitoring and fault prevention.
[0077] The method for evaluating the rotor winding fault risk of a deep peak-shaving steam turbine generator provided in this embodiment can effectively evaluate the rotor winding fault risk of the generator through the cumulative value of the relative displacement between the rotor winding and the rotor core. Through the above fault evaluation method, the health status of the generator rotor winding can be monitored and predicted in real time, faults can be discovered and handled in time, unplanned downtime can be reduced, and power generation efficiency and economy can be improved.
[0078] The specific implementation methods of the present application are described in detail above. Although some embodiments have been shown and described, those skilled in the art should understand that these embodiments can be modified and improved without departing from the principles and spirit of the present application whose scope is defined by the claims and their equivalents. These modifications and improvements should also be within the scope of protection of the present application.
Claims
1. A method for assessing the risk of rotor winding failure of a deep peak-shaving steam turbine generator, characterized in that: The evaluation methods include: Obtain the excitation current multiple of the generator; The average temperature of the rotor winding and the average temperature of the rotor core are calculated according to the excitation current multiple; The axial deformation of the rotor winding is calculated according to the average temperature of the rotor winding, and the axial deformation of the rotor core is calculated according to the average temperature of the rotor core; The relative displacement is calculated according to the axial deformation of the rotor winding and the axial deformation of the rotor core; The failure risk of the generator rotor is evaluated according to the relative displacement.
2. The method for evaluating the risk of rotor winding failure of a deep peak-shaving steam turbine generator according to claim 1, characterized in that: The method for obtaining the excitation current multiple of the generator includes: The actual excitation current is obtained through the generator monitoring system, and the excitation current multiple is calculated according to the following formula: In the formula, I f Indicates the measured excitation current, I fN Indicates the rated excitation current, K f Indicates the excitation current multiple.
3. The method for evaluating the rotor winding failure risk of a deep peak-shaving steam turbine generator according to claim 2 is characterized in that: The method of respectively calculating the average temperature of the rotor winding and the average temperature of the rotor core according to the excitation current multiple comprises: Based on finite element simulation and curve fitting, the relationship function between the steady-state average temperature of the generator rotor winding and the rotor core and the excitation current multiple is established, and the average temperature of the rotor winding and the average temperature of the rotor core during the operation of the generator is calculated in real time through the relationship function. The calculation formula is as follows: Where, T Cu is the average temperature of the rotor winding, a1, a2, a3, a4 are the fitting coefficients of the functional relationship between the average temperature of the rotor winding and the excitation current multiple, T Fe is the average temperature of the rotor core, b1, b2, b3, and b4 are the fitting coefficients of the functional relationship between the average temperature of the rotor core and the excitation current multiple.
4. The method for evaluating the risk of rotor winding failure of a deep peak-shaving steam turbine generator according to claim 3 is characterized in that: The calculation formula for obtaining the axial deformation of the rotor winding according to the average temperature of the rotor winding is as follows: Δl Cu (t)=α Cu ·l Cu ·[T Cu (t)-T Cu0 ] In the formula, Δl C u(t) is the axial deformation of the straight length of the rotor winding at time t, α Cu is the linear thermal expansion coefficient of the rotor winding material, l Cu is the original length of the straight section of the rotor winding, Tcu(t) is the average temperature of the rotor winding at time t during operation, T Cu0 is the rotor winding temperature at the initial moment.
5. The method for evaluating the risk of rotor winding failure of a deep peak-shaving steam turbine generator according to claim 3 is characterized in that: The calculation formula for obtaining the axial deformation of the rotor core according to the average temperature of the rotor core is as follows: Δl Fe (t)=α Fe ·l Fe ·[T Fe (t)-T Fe0 ] In the formula, Δl F e(t) is the axial deformation of the rotor core length at time t, α Fe is the linear thermal expansion coefficient of the rotor core material, l Fe is the original length of the rotor core, T F e(t) is the rotor core temperature at time t during operation, T Fe0 is the rotor core temperature at the initial moment.
6. The method for evaluating the risk of rotor winding failure of a deep peak-shaving steam turbine generator according to claim 3 is characterized in that: The calculation formula for the relative displacement is calculated according to the axial deformation of the rotor winding and the axial deformation of the rotor core as follows: Where Δl represents the relative displacement.