A method and system for identifying risk areas during wide-load operation of mixed-flow turbines

Abstract

This invention relates to the field of mixed-flow turbine technology, specifically to a method and system for identifying risk areas during wide-load operation of mixed-flow turbines. The method includes: acquiring unit operating status parameters and pressure pulsation signals from the draft tube and bladeless zone; decomposing the signals based on variational mode decomposition, filtering vortex band components within a preset frequency band, and calculating the effective amplitude value; obtaining the pressure wave velocity by querying the wave velocity characteristic curve using the guide vane opening, calculating the pressure wave wavelength and geometric position difference, and obtaining the phase resonance risk coefficient; calculating the draft tube vortex band intensity index based on the operating head and the effective amplitude value; comparing the phase resonance risk coefficient and vortex band intensity index with preset thresholds to determine the risk area type of the current operating condition. This invention eliminates the interference of head on amplitude determination through dimensionless processing and corrects the pressure wave velocity, achieving accurate identification of risk areas under wide-load, full-condition operation of mixed-flow turbines.

Description

Technical Field

[0001] This invention relates to the field of mixed-flow turbine technology, and more specifically, to a method and system for identifying risk areas during wide-load operation of mixed-flow turbines. Background Technology

[0002] With the construction of new power systems, mixed-flow turbines need to undertake more frequent peak-shaving tasks, expanding their operating range from a single rated load to a wide range of operating conditions. During wide-load operation, turbines face drastically different hydraulic stability issues. In the low-load region, they are mainly affected by the helical vortex zone in the draft tube, which easily induces low-frequency pressure pulsations. In the high-load and specific opening regions, they are mainly affected by the dynamic and static interference between the runner and guide vanes. When the pressure wave wavelength matches the flow channel geometry, phase resonance occurs, leading to highly destructive high-frequency vibrations.

[0003] The existing technology has the following technical defects in identifying these risks: (1) The existing methods usually monitor the absolute amplitude of low-frequency and high-frequency signals respectively. However, the absolute amplitude is greatly affected by the water head. Directly using the absolute value threshold will lead to false alarms for high water head and missed alarms for low water head. (2) The occurrence of phase resonance depends on the pressure wave velocity. The wave velocity is not a constant, but a variable that is significantly affected by the guide vane opening. When calculating the resonance risk, the existing technology often ignores the correction effect of the guide vane opening on the wave velocity, resulting in a large prediction deviation of the resonance frequency and failing to identify the hidden resonance condition before the vibration diverges.

[0004] Therefore, accurately identifying the high-risk areas of wide-load operation of mixed-flow turbines is a technical problem that urgently needs to be solved. Summary of the Invention

[0005] The purpose of this invention is to provide a method and system for identifying the risk area of ​​wide-load operation of mixed-flow turbines, so as to solve the technical problem of how to accurately identify the risk area of ​​wide-load operation of mixed-flow turbines.

[0006] This invention is achieved through the following technical solution: a method for identifying risk areas during wide-load operation of a mixed-flow turbine, comprising the following steps:

[0007] The unit operating status parameters and dynamic signals of the mixed-flow turbine at the current sampling time are obtained. The operating status parameters include the unit speed, guide vane opening and upstream and downstream water levels. The dynamic signals are pressure pulsation signals arranged in the tailrace and bladeless zone. The pressure pulsation signal is decomposed using variational mode decomposition to obtain several intrinsic mode components. The unit rotational frequency is calculated using the unit speed. Based on the unit rotational frequency, the vortex band component located within a preset frequency band is selected from the several intrinsic mode components, and the effective value of the amplitude of the vortex band component is calculated. ; By querying the preset wave velocity characteristic curve using the guide vane opening, the pressure wave velocity at the current opening is obtained. Based on the pressure wave velocity and the unit speed, the pressure wave wavelength is calculated. Based on the wavelength of the pressure wave and the geometric position difference of the pressure wave propagation when two adjacent excitation events occur. The phase resonance risk coefficient was calculated. ,in, Represents the floor function; The current working head is calculated based on the upstream and downstream water levels. Based on the current working head The tailrace vortex intensity index was calculated from the effective value of the amplitude. ,in, This indicates the density of water. Represents gravitational acceleration; The phase resonance risk coefficient and tailrace vortex strength index The current operating condition is compared with the corresponding preset threshold, and the risk area type is determined based on the comparison result.

[0008] According to a preferred embodiment, the number of modes in the variational mode decomposition is dynamically set, and its calculation expression is as follows: ,in, This indicates the number of modes in the variational mode decomposition. This indicates the rounding up operation. This indicates the highest frequency of interest in signal analysis. This indicates the unit's operating frequency.

[0009] According to a preferred embodiment, the screening of the vortex band components specifically includes: calculating the center frequency of the inherent mode components. ,judge If the frequency band falls within a preset range, then calculate the correlation coefficient between the modal component and the pressure pulsation signal. If the correlation coefficient is greater than a preset value, then determine that the inherent modal component is a vortex band component.

[0010] According to a preferred embodiment, the construction of the preset wave velocity characteristic curve specifically includes: Select guide vane openings covering multiple operating conditions across the full load range. For each opening, establish a full-channel fluid simulation model and calculate the gas phase volume fraction of the fluid in the bladeless region. Based on the gas phase volume fraction, the theoretical pressure wave velocity corresponding to each opening degree is calculated using the gas-liquid two-phase flow sound velocity formula. The guide vane opening is fitted to generate a function with the guide vane opening as the independent variable and the pressure wave velocity as the dependent variable, which serves as the preset wave velocity characteristic curve.

[0011] According to a preferred embodiment, the calculation of the geometric position difference specifically includes: calculating the guide vane distribution arc length corresponding to the angle rotated by the wheel during the rotation of the wheel, within the time interval between two adjacent dynamic-static interference excitation events; if the wheel rotates counterclockwise, then... Take the arc distance between adjacent guide vanes in the counterclockwise direction. If the wheel rotates clockwise, then... Take the arc length distance between adjacent guide vanes in a clockwise direction.

[0012] According to a preferred embodiment, the calculation expression for the pressure wave wavelength is as follows: ,in, This indicates the wave velocity after correction for guide vane opening. Indicates the harmonic order. This indicates the number of rotor blades.

[0013] According to a preferred embodiment, determining the risk zone type of the current operating condition based on the comparison results specifically includes: like and If so, the risk area type is determined to be a stable operating area, where, This represents the first threshold value for vortex zone intensity. Indicates the phase resonance safety threshold; like and If so, the risk area type is determined to be a transitional monitoring zone, where, This represents the second threshold for vortex zone intensity. ; like and If so, the risk area type is determined to be a risk-avoidance area.

[0014] According to a preferred embodiment, the method further includes extracting the frequency characteristics of the measurement point signal in the bladeless zone as the unit rotation frequency when the guide vane opening is less than a set threshold of the rated opening. component amplitude If the component amplitude is detected If the opening of the guide vane increases as the guide vane opening decreases, and the increase exceeds the preset linear slope, then the current operating condition is directly marked as a risk avoidance zone.

[0015] According to a preferred embodiment, the method further includes: constructing a two-dimensional operating plane with guide vane opening as the abscissa and operating head as the ordinate; and drawing and updating the boundary contours of the stable operating zone, the transition monitoring zone, and the risk avoidance zone in the two-dimensional operating plane according to the determined risk zone type.

[0016] This invention also provides a system for identifying risk areas during wide-load operation of mixed-flow turbines, applied to the method for identifying risk areas during wide-load operation of mixed-flow turbines as described above. The system includes: The data synchronization acquisition module is used to acquire the unit operating status parameters and dynamic signals of the mixed-flow turbine at the current sampling time; The signal decomposition module is used to decompose the pressure pulsation signal based on the variational mode decomposition method to obtain several intrinsic mode components, calculate the unit rotation frequency using the unit rotation speed, filter out the vortex band component located in the preset frequency band from the several intrinsic mode components based on the unit rotation frequency, and calculate the effective value of the amplitude of the vortex band component. The first feature calculation module is used to query the preset wave velocity characteristic curve using the guide vane opening, obtain the pressure wave velocity at the current opening, calculate the pressure wave wavelength based on the pressure wave velocity and the unit speed, and calculate the phase resonance risk coefficient based on the pressure wave wavelength and the geometric position difference of the pressure wave propagation when two adjacent excitation events occur. The second feature calculation module is used to calculate the current working head based on the upstream and downstream water levels, and to calculate the tailrace vortex intensity index based on the current working head and the effective value of the amplitude. The risk assessment module is used to compare the phase resonance risk coefficient and the tailrace vortex intensity index with the corresponding preset thresholds, and determine the risk zone type of the current operating condition based on the comparison results.

[0017] The technical solution of the method and system for identifying risk areas during wide-load operation of a mixed-flow turbine provided by this invention has at least the following advantages and beneficial effects: This invention achieves accurate identification of risk areas under wide-load full-condition operation of a mixed-flow turbine; on the one hand, by using real-time upstream and downstream water levels to calculate the working head, the pressure pulsation of the tailrace vortex band is processed dimensionlessly, eliminating the interference of head variation on the absolute amplitude determination, and establishing a unified vortex band evaluation standard applicable to the entire water level range; on the other hand, by using guide vane opening to correct the pressure wave velocity in the bladeless zone, the dynamic and static interference phase resonance risk coefficient is calculated, which can effectively identify the implicit resonance risk caused by wave velocity drift due to changes in the physical properties of the flow field under low load, overcoming the limitation of traditional methods that only rely on amplitude alarms; in addition, by incorporating the vortex band index characterizing fluid instability and the phase resonance coefficient characterizing acoustic resonance risk into a unified decision, a complete operation map including the stable zone, monitoring zone, and avoidance zone is constructed, providing a quantitative, intuitive, and physically interpretable decision basis for the safe scheduling of the unit under deep peak shaving and wide-load scenarios. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the overall process of the method for identifying the risk area of ​​wide-load operation of a mixed-flow turbine provided in Embodiment 1 of the present invention; Figure 2 This is a structural block diagram of the mixed-flow turbine wide-load operation risk area identification system provided in Embodiment 1 of the present invention. Detailed Implementation

[0019] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0020] Example 1 This invention provides a method for identifying risk areas during wide-load operation of mixed-flow turbines. Figure 1 This is a schematic diagram of the overall process for identifying the risk area of ​​wide-load operation of the mixed-flow turbine. (See attached diagram) Figure 1 As shown, the method for identifying risk areas during wide-load operation of a mixed-flow turbine includes the following steps: Step S1: Data synchronization and acquisition; In this embodiment, the step aims to obtain the unit operating status parameters and dynamic signals of the mixed-flow turbine at the current sampling time; in some embodiments, the operating status parameters include the unit speed, guide vane opening and upstream and downstream water levels, and the dynamic signals are pressure pulsation signals arranged in the tailrace and bladeless zone.

[0021] Step S2: Signal decomposition; In this embodiment, this step aims to decompose the pressure pulsation signal based on the variational mode decomposition method to obtain several intrinsic mode components.

[0022] To adapt to changes in unit speed, such as start-up, shutdown, or load shedding, the number of modes in the variational mode decomposition is dynamically set in this embodiment, and its calculation expression is as follows: ,in, This indicates the number of modes in the variational mode decomposition. This indicates the rounding up operation. This indicates the highest frequency of interest in signal analysis. This indicates the unit's operating frequency.

[0023] It should be noted that, compared to empirical mode decomposition, variational mode decomposition can effectively avoid mode aliasing, while dynamic... The value ensures sufficient frequency resolution at different rotational speeds, guaranteeing the integrity of feature extraction.

[0024] Step S3: Screening of vortex components; In this embodiment, the unit rotational frequency is calculated using the unit's rotational speed, and based on this rotational frequency, vortex band components located within a preset frequency band are selected from several inherent mode components. In some implementations, the selection of vortex band components specifically includes: calculating the center frequency of the inherent mode components. ,judge If the frequency band falls within a preset range, then calculate the correlation coefficient between the modal component and the pressure pulsation signal. If the correlation coefficient is greater than a preset value, then determine that the inherent modal component is a vortex band component.

[0025] Furthermore, the effective values ​​of the amplitudes of the selected vortex band components are calculated. , representing the absolute pressure intensity generated by the vortex under the current operating conditions.

[0026] Step S3: Calculate the guide vane opening; In this embodiment, this step identifies potential phase resonance risks by querying a preset wave velocity characteristic curve using the guide vane opening to obtain the pressure wave velocity at the current opening. In some implementations, the construction of the preset wave velocity characteristic curve specifically includes: selecting guide vane openings covering multiple operating conditions across the full load range; for each opening, establishing a full-channel fluid simulation model and calculating the gas phase volume fraction of the fluid in the bladeless region; based on the gas phase volume fraction, calculating the theoretical pressure wave velocity corresponding to each opening using the gas-liquid two-phase flow sound velocity formula; and fitting each opening to generate a functional relationship with the guide vane opening as the independent variable and the pressure wave velocity as the dependent variable as the preset wave velocity characteristic curve. It should be noted that the above design can accurately capture the resonance point shift caused by wave velocity drift.

[0027] Furthermore, the pressure wave wavelength is calculated based on the corrected pressure wave velocity and the unit speed. The expression for calculating the wavelength of the pressure wave is as follows: ,in, This indicates the wave velocity after correction for guide vane opening. Indicates the harmonic order. This indicates the number of rotor blades.

[0028] Furthermore, the geometric position difference of pressure wave propagation at two adjacent excitation events is calculated. In some embodiments, the calculation of the geometric position difference specifically includes: calculating the guide vane distribution arc length corresponding to the angle rotated by the rotor during the rotation of the rotor, within the time interval between two adjacent dynamic-static interference excitation events; if the rotor rotates counterclockwise, then... Take the arc distance between adjacent guide vanes in the counterclockwise direction. If the wheel rotates clockwise, then... Take the arc length distance between adjacent guide vanes in a clockwise direction.

[0029] Furthermore, based on the wavelength of the pressure wave and the geometric position difference of the pressure wave propagation at the occurrence of two adjacent excitation events... The phase resonance risk coefficient was calculated. ,in, This represents the floor function; it should be noted that when near When it is an integer multiple of, Approaching zero means that the pressure waves generated by different flow channels are highly overlapping in phase, resulting in constructive interference and causing huge destructive force. The smaller the value, the greater the risk of resonance.

[0030] It should be noted that this embodiment uses the guide vane opening to correct the pressure wave velocity in the bladeless region and calculates the dynamic-static interference phase resonance risk coefficient. This can effectively identify the hidden resonance risk caused by wave velocity drift due to changes in the physical properties of the low-load flow field, overcoming the limitation of traditional methods that rely solely on amplitude alarms.

[0031] Step S4: Calculate the upstream and downstream water levels; In this embodiment, this step aims to eliminate the interference of head changes on risk assessment by calculating the current working head based on upstream and downstream water levels. Based on the current working head The tailrace vortex intensity index was calculated from the effective value of the amplitude. ,in, This indicates the density of water. This represents gravitational acceleration. It should be noted that the absolute amplitude of pressure pulsations is proportional to the water head. Under high water heads, even normal pulsations may have an absolute value exceeding the fault value under low water heads. This embodiment addresses this by dividing by... By converting absolute pressure into relative pressure fluctuation values, a unified evaluation standard applicable to the entire water level range was established, avoiding false alarms of high head and missed alarms of low head.

[0032] It should be noted that the above method of calculating the working head using real-time upstream and downstream water levels, and performing dimensionless processing on the pressure pulsation of the tailrace vortex, eliminates the interference of head variation on the determination of absolute amplitude, and establishes a unified vortex evaluation standard applicable to the entire water level range.

[0033] Step S5: Risk Assessment; In this embodiment, this step aims to convert the calculated physical indicators into an intuitive operational guidance area; specifically, this embodiment uses the phase resonance risk coefficient... and tailrace vortex strength index The current operating condition is compared with the corresponding preset threshold, and the risk area type is determined based on the comparison result.

[0034] In some implementations, the risk zone type of the current operating condition is determined based on the comparison results, specifically including: like and If so, the risk area type is determined to be a stable operating area, where, This represents the first threshold value for vortex zone intensity. Indicates the phase resonance safety threshold; like and If so, the risk area type is determined to be a transitional monitoring zone, where, This represents the second threshold for vortex zone intensity. ; like and If so, the risk area type is determined to be a risk-avoidance area.

[0035] In a preferred embodiment, when the guide vane opening is less than a set threshold of the rated opening, the frequency characteristics of the measurement point signal in the bladeless zone are extracted as the unit rotation frequency. component amplitude If the component amplitude is detected If the slope increases as the guide vane opening decreases, and the increase exceeds the preset linear slope, then the current operating condition is directly marked as a risk avoidance zone, without relying on... value.

[0036] Furthermore, to intuitively demonstrate the risk identification results, this embodiment constructs a two-dimensional operating plane with guide vane opening as the horizontal axis and operating head as the vertical axis. Based on the determined risk area type, the boundary contours of the stable operating area, the transition monitoring area, and the risk avoidance area are drawn and updated within the two-dimensional operating plane.

[0037] It should be noted that this embodiment incorporates the vortex band index, which characterizes fluid instability, and the phase resonance coefficient, which characterizes acoustic resonance risk, into a unified decision-making process. This constructs a complete operational map that includes a stable zone, a monitoring zone, and a avoidance zone. This provides a quantitative, intuitive, and physically interpretable decision-making basis for the safe scheduling of the unit under deep peak shaving and wide load scenarios. In turn, it enables accurate identification of risk areas of mixed-flow turbines under wide load and full operating conditions.

[0038] Example 2 This embodiment, based on the technical solution provided in Embodiment 1, provides a wide-load operation risk area identification system for mixed-flow turbines. This system applies the wide-load operation risk area identification method for mixed-flow turbines described in Embodiment 1. (See also...) Figure 2 As shown, the system includes: The data synchronization acquisition module is used to acquire the unit operating status parameters and dynamic signals of the mixed-flow turbine at the current sampling time; The signal decomposition module is used to decompose the pressure pulsation signal based on the variational mode decomposition method to obtain several intrinsic mode components, calculate the unit rotation frequency using the unit rotation speed, filter out the vortex band component located in the preset frequency band from the several intrinsic mode components based on the unit rotation frequency, and calculate the effective value of the amplitude of the vortex band component. The first feature calculation module is used to query the preset wave velocity characteristic curve using the guide vane opening, obtain the pressure wave velocity at the current opening, calculate the pressure wave wavelength based on the pressure wave velocity and the unit speed, and calculate the phase resonance risk coefficient based on the pressure wave wavelength and the geometric position difference of the pressure wave propagation when two adjacent excitation events occur. The second feature calculation module is used to calculate the current working head based on the upstream and downstream water levels, and to calculate the tailrace vortex intensity index based on the current working head and the effective value of the amplitude. The risk assessment module is used to compare the phase resonance risk coefficient and the tailrace vortex intensity index with the corresponding preset thresholds, and determine the risk zone type of the current operating condition based on the comparison results.

[0039] The functions of each module of the mixed-flow turbine wide-load operation risk area identification system in this embodiment are the same as those in the embodiment of the mixed-flow turbine wide-load operation risk area identification method, and the technical effects are the same, so they will not be repeated here.

[0040] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for identifying risk areas during wide-load operation of a mixed-flow turbine, characterized in that, Includes the following steps: The unit operating status parameters and dynamic signals of the mixed-flow turbine at the current sampling time are obtained. The operating status parameters include the unit speed, guide vane opening and upstream and downstream water levels. The dynamic signals are pressure pulsation signals arranged in the tailrace and bladeless zone. The pressure pulsation signal is decomposed using variational mode decomposition to obtain several intrinsic mode components. The unit rotational frequency is calculated using the unit speed. Based on the unit rotational frequency, the vortex band component located within a preset frequency band is selected from the several intrinsic mode components, and the effective value of the amplitude of the vortex band component is calculated. ; By querying the preset wave velocity characteristic curve using the guide vane opening, the pressure wave velocity at the current opening is obtained. Based on the pressure wave velocity and the unit speed, the pressure wave wavelength is calculated. Based on the wavelength of the pressure wave and the geometric position difference of the pressure wave propagation when two adjacent excitation events occur. The phase resonance risk coefficient was calculated. ,in, Represents the floor function; The current working head is calculated based on the upstream and downstream water levels. Based on the current working head The tailrace vortex intensity index was calculated from the effective value of the amplitude. ,in, This indicates the density of water. Represents gravitational acceleration; The phase resonance risk coefficient and tailrace vortex strength index The current operating condition is compared with the corresponding preset threshold, and the risk area type is determined based on the comparison result.

2. The method for identifying risk areas during wide-load operation of a mixed-flow turbine as described in claim 1, characterized in that, The number of modes in the variational mode decomposition is dynamically set, and its calculation expression is as follows: ,in, This indicates the number of modes in the variational mode decomposition. This indicates the rounding up operation. This indicates the highest frequency of interest in signal analysis. This indicates the unit's operating frequency.

3. The method for identifying risk areas during wide-load operation of a mixed-flow turbine as described in claim 1, characterized in that, The selection of the vortex band components specifically includes: calculating the center frequency of the inherent mode components. ,judge If the frequency band falls within a preset range, then calculate the correlation coefficient between the modal component and the pressure pulsation signal. If the correlation coefficient is greater than a preset value, then determine that the inherent modal component is a vortex band component.

4. The method for identifying risk areas during wide-load operation of a mixed-flow turbine as described in claim 1, characterized in that, The construction of the preset wave velocity characteristic curve specifically includes: Select guide vane openings covering multiple operating conditions across the full load range. For each opening, establish a full-channel fluid simulation model and calculate the gas phase volume fraction of the fluid in the bladeless region. Based on the gas phase volume fraction, the theoretical pressure wave velocity corresponding to each opening degree is calculated using the gas-liquid two-phase flow sound velocity formula. The guide vane opening is fitted to generate a function with the guide vane opening as the independent variable and the pressure wave velocity as the dependent variable, which serves as the preset wave velocity characteristic curve.

5. The method for identifying risk areas during wide-load operation of a mixed-flow turbine as described in claim 1, characterized in that, The calculation of the geometric position difference specifically includes: calculating the guide vane distribution arc length corresponding to the angle rotated by the rotor during the rotation process, within the time interval between two adjacent dynamic-static interference excitation events; if the rotor rotates counterclockwise, then... Take the arc distance between adjacent guide vanes in the counterclockwise direction. If the wheel rotates clockwise, then... Take the arc length distance between adjacent guide vanes in a clockwise direction.

6. The method for identifying risk areas during wide-load operation of a mixed-flow turbine as described in claim 1, characterized in that, The expression for calculating the wavelength of the pressure wave is as follows: ,in, This indicates the wave velocity after correction for guide vane opening. Indicates the harmonic order. This indicates the number of rotor blades.

7. The method for identifying risk areas during wide-load operation of a mixed-flow turbine as described in claim 1, characterized in that, Based on the comparison results, the risk zone type of the current operating condition is determined, specifically including: like and If so, the risk area type is determined to be a stable operating area, where, This represents the first threshold value for vortex zone intensity. Indicates the phase resonance safety threshold; like and If so, the risk area type is determined to be a transitional monitoring zone, where, This represents the second threshold for vortex zone intensity. ; like and If so, the risk area type is determined to be a risk-avoidance area.

8. The method for identifying risk areas during wide-load operation of a mixed-flow turbine as described in claim 7, characterized in that, The method also includes extracting the frequency characteristics of the measurement point signal in the bladeless zone as the unit's operating frequency when the guide vane opening is less than a set threshold of the rated opening. component amplitude If the component amplitude is detected If the opening of the guide vane increases as the guide vane opening decreases, and the increase exceeds the preset linear slope, then the current operating condition is directly marked as a risk avoidance zone.

9. The method for identifying risk areas during wide-load operation of a mixed-flow turbine as described in claim 8, characterized in that, The method also includes: constructing a two-dimensional operating plane with guide vane opening as the abscissa and operating head as the ordinate; and drawing and updating the boundary contours of the stable operating zone, the transition monitoring zone and the risk avoidance zone in the two-dimensional operating plane according to the determined risk zone type.

10. A system for identifying risk areas during wide-load operation of a mixed-flow turbine, characterized in that, The system, applied to the method for identifying risk areas of wide-load operation of mixed-flow turbines as described in any one of claims 1 to 9, comprises: The data synchronization acquisition module is used to acquire the unit operating status parameters and dynamic signals of the mixed-flow turbine at the current sampling time; The signal decomposition module is used to decompose the pressure pulsation signal based on the variational mode decomposition method to obtain several intrinsic mode components, calculate the unit rotation frequency using the unit rotation speed, filter out the vortex band component located in the preset frequency band from the several intrinsic mode components based on the unit rotation frequency, and calculate the effective value of the amplitude of the vortex band component. The first feature calculation module is used to query the preset wave velocity characteristic curve using the guide vane opening, obtain the pressure wave velocity at the current opening, calculate the pressure wave wavelength based on the pressure wave velocity and the unit speed, and calculate the phase resonance risk coefficient based on the pressure wave wavelength and the geometric position difference of the pressure wave propagation when two adjacent excitation events occur. The second feature calculation module is used to calculate the current working head based on the upstream and downstream water levels, and to calculate the tailrace vortex intensity index based on the current working head and the effective value of the amplitude. The risk assessment module is used to compare the phase resonance risk coefficient and the tailrace vortex intensity index with the corresponding preset thresholds, and determine the risk zone type of the current operating condition based on the comparison results.

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