A vibration cooperative suppression control method and system for a multi-unit hydropower station

Abstract

The application discloses a kind of multi-unit hydroelectric power station's vibration synergic inhibition control method and system, it is related to data processing technical field, method includes: obtaining unit, obtains the vibration data sequence of unit;According to vibration data sequence obtains the i target time period, obtains the i target time point;Obtain comparison data sequence, obtain the i comparison time period, obtain the first end time point of the i comparison time period and as the i comparison time point of adjacent unit;According to the i target time point and the i comparison time point of each adjacent unit of the i target unit, obtain the transfer coefficient between the i target unit and each adjacent unit of the i target unit;Obtain the real-time vibration amplitude of the i target unit, and according to the real-time vibration amplitude of the i target unit and transfer coefficient, obtain the synergic inhibition control strategy of the i target unit and the adjacent unit of the i target unit.The present application has the advantages of transmission intensity identification, transmission phase compensation and multi-unit cooperation.

Description

Technical Field

[0001] This invention relates to the field of data processing technology, specifically to a method and system for coordinated vibration suppression control in multi-unit hydropower stations. Background Technology

[0002] When multiple units of a hydropower station are operating in parallel, vibrations caused by hydraulic disturbances (such as vortex belts and pressure pulsations) can be transmitted between adjacent units through shared flow channels, foundation structures, or power grid coupling, forming a vibration energy transmission chain. This can affect the efficiency and effectiveness of existing vibration suppression and control systems.

[0003] Specifically, independent regulation by each unit (e.g., adjusting guide vane opening only based on its own vibration amplitude) ignores the vibration transmission effect, leading to regulation lag (e.g., unit B only initiates suppression after vibration transmission arrives, missing the optimal intervention opportunity) and cascading deterioration (e.g., load reduction and vibration mitigation operations of unit A may exacerbate the vibration of unit B, and flow redistribution induces vortex bands), resulting in vibration transfer phenomena between units. Furthermore, existing technologies rely on fixed thresholds for spectral analysis to determine the source of vibration, but cannot dynamically quantify the transmission intensity and direction, nor can they quickly and effectively distinguish between their own hydraulic resonance and adjacent transmission. More importantly, the lack of a quantitative mechanism for the degree of transmission leads to collaborative strategies relying solely on experience to allocate regulation intensity, resulting in over-regulation (units are excessively suppressed, sacrificing power generation efficiency) or under-regulation (insufficient unit suppression, and vibration continues to spread). Finally, vibration transmission has strict temporal characteristics, but existing methods fail to capture the temporal logic of the vibration rise edge. Regulation commands lose phase coordination due to a lack of temporal alignment, and may even amplify vibration due to reverse superposition. Summary of the Invention

[0004] To address the technical problems of existing technologies that cannot accurately quantify transmission relationships and cannot dynamically coordinate the regulation of multiple generating units, this invention provides a vibration coordinated suppression control method and system for multi-generator hydropower stations.

[0005] A vibration collaborative suppression control method for a multi-unit hydropower station includes: acquiring multiple units arranged sequentially, and acquiring vibration data sequences of each unit in the previous monitoring cycle; acquiring an i-th target time period representing the increase in vibration intensity of the i-th unit based on the vibration data sequence of the i-th unit, and acquiring the first time point of the i-th target time period as the i-th target time point; acquiring vibration data sequences of adjacent units of the i-th unit as comparison data sequences, and acquiring an i-th comparison time period representing the increase in vibration intensity of adjacent units based on the comparison data sequences after the i-th target time point, and acquiring the first time point of the i-th comparison time period as the i-th comparison time point of adjacent units; acquiring the transmission coefficient between the i-th unit and each of the adjacent units of the i-th unit based on the i-th target time point and the i-th comparison time points of each of the adjacent units of the i-th unit; acquiring the real-time vibration amplitude of the i-th unit, and acquiring a collaborative suppression control strategy between the i-th unit and its adjacent units based on the real-time vibration amplitude and the transmission coefficient of the i-th unit.

[0006] Optionally, obtaining the i-th target time period representing the increase in vibration intensity of the i-th unit based on the vibration data sequence of the i-th unit includes: obtaining the first change between the next vibration amplitude and the previous vibration amplitude in the vibration data sequence of the i-th unit; dividing the vibration data sequence of the i-th unit into multiple continuously increasing data segments, wherein each continuously increasing data segment contains at least two vibration amplitudes, and the first change between each adjacent vibration amplitude in each continuously increasing data segment is greater than zero; obtaining the continuously increasing data segment containing the most vibration amplitudes and taking the continuous time range corresponding to the continuously increasing data segment as the i-th target time period.

[0007] Optionally, obtaining the i-th comparison time period representing the increase in vibration intensity of adjacent units based on the comparison data sequence after the i-th target time point includes: taking the comparison data sequence after the i-th target time point as the i-th valid data sequence, and obtaining the second change between the next vibration amplitude and the previous vibration amplitude in the i-th valid data sequence; dividing the i-th valid data sequence into multiple continuously increasing data segments, wherein each continuously increasing data segment contains at least two vibration amplitudes, and the second change between each adjacent vibration amplitude in each continuously increasing data segment is greater than zero; obtaining the continuously increasing data segment containing the most vibration amplitudes and taking the continuous time range corresponding to the continuously increasing data segment as the i-th comparison time period.

[0008] Optionally, obtaining the transmission coefficient between the i-th unit and each of the i-th adjacent units based on the i-th target time point and the i-th comparison time point of each of the i-th unit's adjacent units includes: obtaining a standard transmission time difference range, and obtaining the minimum transmission time gap and the maximum transmission time gap based on the standard transmission time difference range; obtaining the transmission coefficient between the i-th unit and the j-th adjacent unit of the i-th unit based on the i-th target time point, the i-th comparison time point of the j-th adjacent unit of the i-th unit, the minimum transmission time gap, and the maximum transmission time gap.

[0009] Optionally, the transfer coefficient between the i-th unit and its j-th adjacent unit is expressed as: ;in, Let be the transfer coefficient between the i-th unit and its j-th adjacent unit. For the i-th comparison time point of the j-th adjacent unit of the i-th unit, For the i-th target time point, To minimize the transmission time gap, This represents the maximum transmission time interval.

[0010] Optionally, obtaining the coordinated suppression control strategy for the i-th unit and its adjacent units based on the real-time vibration amplitude and transmission coefficient of the i-th unit includes: obtaining a first suppression command for the i-th unit based on the real-time vibration amplitude of the i-th unit, wherein the first suppression command includes a first adjustment item and first adjustment data corresponding to the first adjustment item; obtaining a second suppression command for the adjacent units of the i-th unit, wherein the second suppression command includes a second adjustment item and second adjustment data corresponding to the second adjustment item, wherein the second adjustment item is the same as the first adjustment item, and the second adjustment data is obtained through the transmission coefficient of the adjacent units of the i-th unit and the first adjustment data; and forming a coordinated suppression control strategy based on the first suppression command of the i-th unit and the second suppression command of the adjacent units of the i-th unit.

[0011] A vibration collaborative suppression control system for a multi-unit hydropower station is also provided. The system includes: a data acquisition module for acquiring multiple units arranged sequentially, and acquiring the vibration data sequence of each unit in the previous monitoring cycle of the current monitoring cycle; a first data processing module for acquiring the i-th target time period representing the increase in vibration intensity of the i-th unit based on the vibration data sequence of the i-th unit, and acquiring the beginning time point of the i-th target time period as the i-th target time point; and a second data processing module for acquiring the vibration data sequences of adjacent units of the i-th unit as comparison data sequences, and acquiring the vibration data sequence representing the vibration of adjacent units based on the comparison data sequence after the i-th target time point. The intensity enhancement occurs during the i-th comparison time period. The first time point of the i-th comparison time period is obtained and used as the i-th comparison time point of the adjacent units. The third data processing module is used to obtain the transmission coefficient between the i-th unit and each of the i-th unit's adjacent units based on the i-th target time point and the i-th comparison time points of each of the i-th unit's adjacent units (the closer the i-th target time point and the i-th comparison time point are, the faster the transmission speed between the adjacent units and the higher the degree of influence). The suppression control module is used to obtain the real-time vibration amplitude of the i-th unit and obtain the cooperative suppression control strategy between the i-th unit and its adjacent units based on the real-time vibration amplitude and transmission coefficient of the i-th unit.

[0012] Optionally, the first data processing module is further configured to: obtain the first change between the vibration amplitude of the next vibration and the previous vibration in the vibration data sequence of the i-th unit; divide the vibration data sequence of the i-th unit into multiple continuously increasing data segments, wherein each continuously increasing data segment contains at least two vibration amplitudes, and the first change between each adjacent vibration amplitude in each continuously increasing data segment is greater than zero; obtain the continuously increasing data segment containing the most vibration amplitudes and take the continuous time range corresponding to the continuously increasing data segment as the i-th target time period.

[0013] Optionally, the second data processing module is further configured to: take the comparison data sequence after the i-th target time point as the i-th valid data sequence, and obtain the second change between the next vibration amplitude and the previous vibration amplitude in the i-th valid data sequence; divide the i-th valid data sequence into multiple continuous lifting data segments, wherein each continuous lifting data segment contains at least two vibration amplitudes, and the second change between each adjacent vibration amplitude in each continuous lifting data segment is greater than zero; obtain the continuous lifting data segment containing the most vibration amplitudes and take the continuous time range corresponding to the continuous lifting data segment as the i-th comparison time period.

[0014] Optionally, the third data processing module is also used to: obtain the standard transmission time difference range, and obtain the minimum transmission time gap and the maximum transmission time gap according to the standard transmission time difference range; and obtain the transmission coefficient between the i-th unit and the j-th adjacent unit of the i-th unit according to the i-th target time point, the i-th comparison time point of the j-th adjacent unit of the i-th unit, the minimum transmission time gap and the maximum transmission time gap.

[0015] The beneficial effects of this invention are reflected in:

[0016] In the vibration collaborative suppression and control method of the entire multi-unit hydropower station, firstly, a dynamic identification framework for transmission effect is constructed based on the spatiotemporal calibration of the physical structure and the capture of the vibration rising edge. The direction, intensity and timing of vibration transmission are quantified, so that the transmission relationship is transformed from qualitative judgment to data-quantified representation of the transmission coefficient, eliminating the defects of the threshold method in misjudging self-resonance and transmission interference. Furthermore, in the source and transmission difference adjustment mechanism in the collaborative strategy generation, preventive control is implemented on adjacent units based on the transmission coefficient with dynamic weight correction. Units with strong transmission relationship receive a high proportion of adjustment to block the energy chain, while units with weak transmission relationship perform micro-prevention to avoid over-adjustment. Phase compensation and timing delay can also be injected to ensure that the adjustment command is strictly aligned with the vibration wave propagation phase, thereby physically destroying the coherent superposition condition of vibration transmission. Attached Figure Description

[0017] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the accompanying drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. In all the drawings, similar elements or parts are generally identified by similar reference numerals. In the drawings, the elements or parts are not necessarily drawn to scale.

[0018] Figure 1 This is a partial flowchart of the vibration coordinated suppression and control method for multi-unit hydropower stations of the present invention;

[0019] Figure 2 This is a schematic diagram of another part of the vibration coordinated suppression and control method for multi-unit hydropower stations of the present invention;

[0020] Figure 3 This is a schematic diagram of another part of the vibration coordinated suppression and control method for multi-unit hydropower stations of the present invention;

[0021] Figure 4 This is a schematic diagram of the steps of the vibration coordinated suppression and control method for multi-unit hydropower stations of the present invention;

[0022] Figure 5 This is a schematic diagram of part of step S2 in the vibration collaborative suppression control method for multi-unit hydropower stations of the present invention;

[0023] Figure 6 This is a schematic diagram of part of step S3 in the vibration collaborative suppression and control method for multi-unit hydropower stations of the present invention;

[0024] Figure 7 This is a schematic diagram of a portion of step S4 in the vibration collaborative suppression and control method for multi-unit hydropower stations of the present invention;

[0025] Figure 8 This is a schematic diagram of part of step S5 in the vibration collaborative suppression and control method for multi-unit hydropower stations of the present invention. Detailed Implementation

[0026] 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.

[0027] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0028] It should be noted that similar reference numerals and letters in the following figures indicate similar items; therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures. Furthermore, the terms "first," "second," etc., are used only to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0029] like Figure 1 , Figure 2 , Figure 3 and Figure 4 As shown, a vibration collaborative suppression and control method for a multi-unit hydropower station is provided. In one embodiment, the method includes:

[0030] S1. Obtain multiple units set sequentially, and obtain the vibration data sequence of each unit in the previous monitoring cycle of the current monitoring cycle;

[0031] S2. Based on the vibration data sequence of the i-th unit, obtain the i-th target time period to represent the increase in vibration intensity of the i-th unit, and obtain the first time point of the i-th target time period as the i-th target time point;

[0032] S3. Obtain the vibration data sequence of the adjacent units of the i-th unit and use it as the comparison data sequence. Based on the comparison data sequence after the i-th target time point, obtain the i-th comparison time period to represent the increase in vibration intensity of the adjacent units. Obtain the first time point of the i-th comparison time period and use it as the i-th comparison time point of the adjacent units.

[0033] S4. Obtain the transfer coefficients between the i-th unit and its neighboring units based on the i-th target time point and the i-th comparison time point of each neighboring unit of the i-th unit;

[0034] S5. Obtain the real-time vibration amplitude of the i-th unit, and obtain the cooperative suppression control strategy of the i-th unit and its adjacent units based on the real-time vibration amplitude and transmission coefficient of the i-th unit.

[0035] In this embodiment, it should be noted that the "i" appearing in S2, S3, S4 and S5 all represent i in the i-th unit. The i-th unit can be any unit, i is a positive integer and does not exceed the maximum number of units.

[0036] In S1, a spatiotemporal baseline for vibration event analysis is established. This step requires acquiring two key dimensions: First, the spatial topology information of the generating units, i.e., clarifying the physical arrangement order of each generating unit in the hydropower station (such as their series connection along the water flow direction), which is crucial for subsequent identification of vibration transmission paths; second, time series data, which requires collecting the historical vibration intensity records of each unit within a complete monitoring period (e.g., the first 10 minutes). These vibration amplitude data are continuously recorded at fixed sampling intervals, forming a traceable fluctuation curve. For example, if the hydropower station has three units A, B, and C connected in series, it is necessary to obtain the vibration amplitude values ​​of each unit sampled every 5 seconds in the previous monitoring period (e.g., 08:00-08:10), forming three time series containing 120 data points each.

[0037] Furthermore, spatiotemporal calibration lays the foundation for subsequent analysis: spatially, the unit sequence identifies potential channels for vibration transmission (such as the transmission direction A→B→C); temporally, historical vibration sequences provide a complete evolutionary trajectory of vibration fluctuations. For example, when unit B experiences sudden high-frequency vibration at 08:05, comparing the vibration data of units A and C during the same time period allows for a preliminary judgment on whether it is due to its own hydraulic resonance or interference transmitted from unit A. This is the fundamental condition for accurately identifying the transmission effect.

[0038] In S2, the most critical growth phase of vibration intensity is located from historical vibration data. This process first extracts the local trend of the vibration sequence through differential analysis (subtracting the previous value from the subsequent value of adjacent data points), screening all continuous data segments exhibiting a "strictly monotonically increasing" amplitude—meaning each data point within a segment must be strictly higher than the previous one, ensuring a continuous increase in vibration intensity (e.g., a unit's vibration amplitude forms a continuous segment from 20→25→30µm, while 20→25→22µm is excluded due to its decreasing trend). Subsequently, the longest continuous segment is selected as the target time period, representing the most significant and sustained vibration enhancement process (e.g., a unit experiences six consecutive increases within 3 minutes, while other segments only experience 1-3 increases; this 3-minute segment is selected). Finally, its starting moment is taken as the target time point, marking the turning point where vibration enters a rapid increase phase, providing a benchmark anchor for subsequent transmission timeliness analysis.

[0039] Furthermore, to illustrate with an example, consider the vibration fluctuations of a hydroelectric power station unit C within a 10-minute monitoring cycle: a brief increase followed by a decrease from 08:01 to 08:02, a continuous increase from 08:03 to 08:06 (with the amplitude gradually increasing from a low value), and stabilization after 08:07. The system will automatically divide the vibration into two increasing segments: 08:01-08:02 and 08:03-08:06. Since the 08:03-08:06 segment covers four consecutive growth points (the longest time span), it is selected as the target time period, with its starting time of 08:03 being the target time point. This indicates that unit C initiates the main vibration enhancement process at 08:03, while the brief fluctuation segment is ignored due to insufficient duration. This design filters out transient interference and focuses on the growth phase that is indicative of the transmitted effect.

[0040] In S3, the temporal response characteristics of vibration transmission are captured. Using the vibration rise point (target time point i) of the target unit (i-th unit) as the benchmark, only the vibration data sequence of adjacent units after that time point is analyzed. Through second-order processing of the vibration data of adjacent units: first, the amplitude increment between adjacent sampling points is calculated (requiring the subsequent value to be strictly greater than the previous value), filtering out all data segments with a continuous growth trend; then, the segment with the longest duration among these rising segments is selected as the critical response interval (i.e., the i-th comparison time period). This design includes a dual filtering mechanism: 1) Time window filtering eliminates irrelevant fluctuations before the target unit's vibration enhancement; 2) Continuous growth determination ensures that the vibration enhancement process caused by the transmission effect, which has inertia, is locked in, avoiding misjudging brief disturbances as a transmission response.

[0041] Furthermore, for example, when unit A is identified as experiencing a significant increase in vibration starting at time t0 (determined by S2), only the vibration curve of the adjacent unit B after time t0 is analyzed. If unit B experiences brief fluctuations during the period [t1, t2] and then shows a stable increase across 5 consecutive sampling points (with progressively increasing amplitude) during the period [t3, t4], the former will be automatically ignored, and [t3, t4] will be selected as the comparison period, with t3 as the comparison time point. The time difference between this time point t3 and t0 reflects the transmission time of vibration from A to B. It is worth noting that if an adjacent unit does not exhibit a continuous upward segment that meets the conditions after t0, it is determined that the unit is not affected by the transmission (e.g., if unit C only fluctuates without growth after t0, it is directly excluded from subsequent coordinated control). This mechanism improves the noise resistance of transmission path identification.

[0042] In S4, a precise quantification mechanism for vibration transmission relationships is established. S4 uses the pre-determined target time point (the onset of vibration enhancement) and the comparison time point (the onset of response from adjacent units) as key inputs, and constructs a quantification model of the transmission coefficient through time difference analysis. In specific implementation, physical constraints are first preset: based on the unit's structural characteristics (such as flow channel length and material rigidity), reasonable time range boundary values ​​for vibration transmission (minimum time gap a, maximum time gap b) are determined. These two boundary values ​​form a standard transmission time frame, ensuring that the quantification results conform to engineering reality (for example, water hammer effect transmission is typically within the range of 1-60 seconds).

[0043] Furthermore, the time difference between the response time of each adjacent unit and the target time of the vibration source is calculated, and this time difference is mapped to a preset boundary value range for dynamic evaluation. The mapping principle reflects three-order characteristics: 1) When the time difference is less than the minimum time interval 'a', it is determined to be instantaneous transmission (assigned the highest coefficient); 2) When the time difference is greater than the maximum time interval 'b', it is determined to be weakly correlated transmission (assigned the lowest coefficient); 3) When the time difference is between 'a' and 'b', it is mapped to an intermediate value through a monotonically decreasing function. For example, in a hydropower station, 'a' is set to 3 seconds (shortest transmission time in the flow channel) and 'b' to 30 seconds (maximum attenuation time of structural damping). If unit B responds 5 seconds after unit A vibrates, then the time difference of 5 seconds is within the effective range, obtaining a medium transmission coefficient; if another unit C responds after 50 seconds (exceeding the value of 'b'), it is considered a non-transmissible fluctuation (assigned the lowest coefficient).

[0044] Furthermore, for example, suppose three generator units are arranged in series (A→B→C direction). Generator unit A begins to vibrate significantly at time t0 (S2 determines the target time point). Analysis in S3 shows that generator unit B exhibits a stable increasing response at time t1 (time difference 1 = t1 - t0 = 4 seconds), and generator unit C exhibits a stable increasing response at time t2 (time difference 2 = t2 - t0 = 25 seconds). The transmission coefficient is calculated using preset boundary values ​​(a = 3 seconds, b = 30 seconds): the time difference 1 (4 seconds) for generator unit B is greater than a but much less than b, corresponding to a medium-high transmission coefficient, reflecting a relatively fast transmission speed; the time difference 2 (25 seconds) for generator unit C is close to the upper limit of b, corresponding to a medium-low transmission coefficient, reflecting a decaying transmission effect; if generator unit D responds after 35 seconds (time difference > 30 seconds), it is directly determined as an irrelevant disturbance. In summary, this quantification mechanism identifies generator unit B as the direct transmission target (requiring key control), distinguishes the weak correlation of generator unit C (avoiding over-adjustment), and eliminates invalid interference sources (such as generator unit D). This ultimately forms a spatially distributed transmission coefficient matrix, providing a quantitative basis for collaborative control.

[0045] In S5, the quantified results of vibration transmission are transformed into a spatially linked dynamic control strategy to address the timing misalignment and cascading deterioration problems caused by existing independent regulation. Specifically, firstly, a first suppression command is generated based on the real-time vibration amplitude of the i-th unit. This command includes specific regulation items (such as guide vane opening, blade angle, and power generation load) and precise regulation data. The key is to establish a nonlinear mapping relationship between vibration intensity and regulation strength: if the vibration approaches the critical threshold, high-intensity regulation is initiated (such as a significant load reduction to disrupt vortex band formation); if it is a low-amplitude vibration, a gradual fine-tuning is adopted (such as a 0.5% adjustment of the guide vane opening). This step is entirely customized based on its own vibration characteristics, avoiding under-regulation or over-regulation caused by experience-based judgment. For example, when unit A experiences a sudden high-frequency pressure pulsation, its vibration energy distribution is monitored in real time. If it is determined that the tailrace vortex band is dominant, a command is generated to "reduce guide vane opening by X% and simultaneously reduce load by Y%" (the X / Y value is dynamically calculated based on the vibration amplitude), rather than triggering a fixed threshold.

[0046] Secondly, a second suppression command is generated for adjacent units, with adjustment items identical to those of the source unit (e.g., both involving guide vane opening adjustment). However, the adjustment data needs to be dynamically corrected using the transmission coefficient. A strong transmission relationship (transmission coefficient > 0.8) indicates that the adjustment intensity is close to that of the source unit (e.g., if unit B experiences 90% of the transmission effect of unit A, then 95% of the source unit's adjustment amount is used); a weak transmission relationship (transmission coefficient < 0.3) indicates that only preventative fine-tuning is initiated (e.g., if unit C has a transmission coefficient of 0.2, the adjustment amount is reduced to 20% of the source unit's). In summary, by introducing the principle of reverse phase compensation, when the transmission coefficient shows rapid transmission (e.g., time difference < 5 seconds), a phase advance compensation term is added to the command, causing the adjustment action to be executed half a vibration cycle in advance, physically blocking the energy transmission chain.

[0047] Ultimately, the strategy integrates all instructions from the source unit and adjacent units, injects key timing constraints, and sorts the units along the water flow direction (e.g., A→B→C) so that the instruction from the downstream unit is delayed by half the time difference from the upstream unit (e.g., unit B executes 2 seconds later than unit A). Simultaneously, the vibration transmission coefficient is monitored in real time after execution. If the vibration of a unit does not attenuate, a second collaborative iteration is automatically triggered (e.g., if the vibration of unit C continues after adjustment, the transmission coefficient is recalculated and further adjustments are made).

[0048] In summary, the vibration collaborative suppression and control method for the entire multi-unit hydropower station firstly constructs a dynamic identification framework for transmission effects based on the spatiotemporal calibration of the physical structure and the capture of vibration rising edges, and realizes the quantification of vibration transmission direction, intensity, and timing, transforming the transmission relationship from qualitative judgment to data-quantified representation of transmission coefficients, thus eliminating the defects of the threshold method in misjudging self-resonance and transmission interference. Furthermore, in the source and transmission difference adjustment mechanism in the collaborative strategy generation, preventive control is implemented on adjacent units based on the transmission coefficient with dynamic weight correction. Units with strong transmission relationships receive a high proportion of adjustment to block the energy chain, while units with weak transmission relationships perform minor prevention to avoid over-adjustment. Phase compensation and timing delay can also be injected to ensure that the adjustment command is strictly aligned with the vibration wave propagation phase, thereby physically disrupting the coherent superposition condition of vibration transmission.

[0049] like Figure 5 As shown, in one embodiment, S2, obtaining the i-th target time period representing the increase in vibration intensity of the i-th unit based on the vibration data sequence of the i-th unit includes:

[0050] S21. Obtain the first change between the vibration amplitude of the next vibration and the previous vibration in the vibration data sequence of the i-th unit.

[0051] S22. Divide the vibration data sequence of the i-th unit into multiple continuously increasing data segments, wherein each continuously increasing data segment contains at least two vibration amplitudes, and the first change between each adjacent vibration amplitude in each continuously increasing data segment is greater than zero.

[0052] S23. Obtain the continuous lifting data segment containing the largest number of vibration amplitudes and take the continuous time range corresponding to the continuous lifting data segment as the i-th target time period.

[0053] In this embodiment, it should be noted that in S21, by calculating the vibration amplitude increment (the latter value minus the former value) between adjacent sampling points, the basic quantitative analysis of the vibration change trend is realized. This operation is essentially the discretized implementation of differentiation. By capturing the vibration amplitude difference between adjacent time points, a data basis is established for subsequent judgment of the growth trend. For example, in the vibration sequence of a certain unit, there are consecutive records of amplitude A → amplitude B → amplitude C. If B > A and C > B, two positive change amounts are obtained, reflecting the continuous enhancement of the vibration intensity; conversely, if C < B, the corresponding change amount is negative, revealing the interruption of growth.

[0054] In S22, the change amount sequence is subjected to segmented processing. By identifying continuous strictly increasing intervals (requiring that each adjacent change amount is strictly greater than zero), the original vibration sequence is divided into several continuous ascending segments with clear monotonicity. This processing contains two key mechanisms: one is to exclude any negative growth or zero growth points, ensuring that the vibration within the segment is in a pure enhancement state; the other is to enforce that the segment length contains at least two data points to avoid interference from isolated fluctuations. For example, in the 20-minute monitoring data of a certain unit, there may be 3 consecutive growth periods: the first period (continuous growth for 5 minutes), the second period (brief growth for 1 minute), and the third period (stable growth for 8 minutes), and finally 3 independent ascending segments are extracted.

[0055] In S23, importance ranking is performed on the segmented results of S22, and the segment containing the most consecutive growth points is selected as the target time period. This strategy is essentially to identify the growth process with the strongest vibration energy and the most significant persistence, because it is most indicative of the transmission effect. In implementation, the maximum value is determined by comparing the number of continuous sampling points (not the time span) of each ascending segment. For example, in the aforementioned case, the third segment contains 16 consecutive growth points, far exceeding 10 points in the first segment and 4 points in the second segment, so the corresponding time period is determined as the target time period.

[0056] As Figure 6 shown, in one embodiment, in S3, obtaining the i-th comparison time period for representing the vibration intensity enhancement of adjacent units according to the comparison data sequence after the i-th target time point includes:

[0057] S31. Taking the comparison data sequence after the i-th target time point as the i-th valid data sequence, and obtaining the second change amount between the latter vibration amplitude and the former vibration amplitude in the i-th valid data sequence;

[0058] S32. Dividing the i-th valid data sequence into multiple continuous ascending data segments, where each continuous ascending data segment contains at least two vibration amplitudes, and the second change amount between each adjacent vibration amplitude in each continuous ascending data segment is greater than zero;

[0059] S33. Obtain the continuous lifting data segment containing the largest number of vibration amplitudes and use the continuous time range corresponding to the continuous lifting data segment as the i-th comparison time period.

[0060] In this embodiment, it should be noted that in S31, the vibration increment calculation (subtracting the previous value from the later value) is performed on the adjacent unit data within the observation window after the target time point, just as in S21. Its core innovation lies in the time window filtering mechanism: it only focuses on the data of adjacent units after the target unit begins to vibrate significantly (the starting point is determined by S23). For example, if target unit A triggers enhancement at t0, then only the vibration sequence of unit B after t0 is extracted for change calculation, avoiding interference from historically irrelevant fluctuations.

[0061] In S32, the segmented logic of S22 is reproduced under the time window constraint, but the inertial characteristic judgment of the physical transmission response is introduced: only when the adjacent units show a continuous increase after the target time point (each change > 0) is it considered a valid transmission response segment. This design effectively distinguishes between autonomous vibration and transmission-induced vibration. For example, if unit B shows a continuous increase for 2 minutes after t0 (forming 10 positive changes), while interspersed with 3 brief fluctuations within 1 minute (changes alternating between positive and negative), only the former is identified as a valid boost segment.

[0062] In S33, the selection strategy of S23 is followed, but the temporal correlation of the response is emphasized: the longest-lasting continuously growing segment is selected from the multiple segments divided in S32 as the response marker. The starting time of this segment is used for comparison, reflecting the time required for vibration energy to be transferred from the source to the target unit. For example, if unit B forms three effective segments (containing 5 / 8 / 12 growth points) after t0, the longest segment containing 12 points is selected, and the time difference between its starting time t1 and t0 quantifies the transmission speed. If no segment meets the criteria, it is determined that there is no transmission effect.

[0063] like Figure 7 As shown, in one embodiment, S4, obtaining the transfer coefficients between the i-th unit and its neighboring units based on the i-th target time point and the i-th comparison time point of each of the i-th unit's neighboring units includes:

[0064] S41. Obtain the standard transmission time difference range, and obtain the minimum transmission time gap and the maximum transmission time gap based on the standard transmission time difference range;

[0065] S42. Obtain the transmission coefficient between the i-th unit and the j-th adjacent unit of the i-th unit based on the i-th target time point, the i-th comparison time point of the j-th adjacent unit of the i-th unit, the minimum transmission time gap, and the maximum transmission time gap.

[0066] In this embodiment, it should be noted that in S41, a physical criterion for the rationality of the transmission effect is established. This step, based on the hydraulic and mechanical characteristics of the hydropower station unit structure (such as the flow channel geometry, unit spacing, and structural material damping coefficient), determines the reasonable time range boundary required for the transmission of vibration energy between units. Through engineering practice data and fluid dynamics models, a minimum transmission time gap (a) is set to reflect the shortest theoretical propagation time of the vibration wave (e.g., the sound speed propagation limit of pressure pulsation in a steel flow channel), while a maximum transmission time gap (b) is set to characterize the effective attenuation time window of vibration energy due to fluid viscosity damping and structural dissipation (exceeding this time is considered as complete dissipation of vibration energy). These two boundary values ​​constitute a rigid physical constraint framework. For example, for a specific hydropower station layout, if the unit spacing in the water flow direction is 80 meters and the pressure wave velocity is 1200 m / s, then the minimum gap a must not be less than 67 milliseconds; if the structural damping test shows that the vortex energy attenuates by 90% in 30 seconds, then the maximum gap b is set to 30 seconds.

[0067] In S42, the focus is on implementing a dynamic quantitative assessment mechanism for transmission effects. This process first calculates the actual time difference between the response start time of each adjacent unit (the i-th comparison time point) and the vibration source enhancement start time (the i-th target time point). Then, a three-threshold strategy is used for hierarchical mapping: 1) When the time difference is less than 'a', it is determined to be ultra-high-speed transmission (such as direct mechanical coupling of the structure), and a high transmission coefficient is assigned; 2) When the time difference is in the 'ab' interval, a progressive decay mapping function is used, causing the transmission coefficient to decrease non-linearly as the time difference increases; 3) When the time difference is greater than 'b', it is determined to be an independent random disturbance, and a baseline coefficient approaching zero is assigned. The mapping principle accurately reflects the time-sensitive characteristics of the transmission intensity: upstream units in the flow channel typically receive a high coefficient for adjacent downstream units (e.g., a coefficient of 0.85 from unit A to B), while assigning a low coefficient to distant units (e.g., only 0.15 from unit A to D). This quantitative result can generate a vibration transmission heatmap, visually indicating strongly coupled unit pairs (requiring key intervention) and weakly correlated unit pairs (which can be safely downgraded for control).

[0068] In one implementation, the transfer coefficient between the i-th unit and its j-th adjacent unit obtained in S4 or S42 is expressed as:

[0069] ;in,

[0070] Let be the transfer coefficient between the i-th unit and its j-th adjacent unit. For the i-th comparison time point of the j-th adjacent unit of the i-th unit, For the i-th target time point, To minimize the transmission time gap, This represents the maximum transmission time interval.

[0071] In this embodiment, it should be noted that in the whole expression, For the time difference benchmarking process, it is ensured that the time difference is not lower than the physical minimum transfer time (set threshold a). When the actual time difference < a, it is forced to be increased to a to avoid outliers beyond the physical limit. For example, when the actual vibration transfer takes 0.2 seconds (a = 0.3 seconds), it is still calculated as 0.3 seconds.

[0072] Furthermore, min{result of the previous step, b} is for the control of the attenuation of the transfer effect. The maximum effective transfer time b (such as 3 seconds) is set. When the time difference > b, the value of b is forced to be taken and marked as a negligible weak transfer. Example: If unit C responds after 4 seconds (b = 3), it is regarded as a non-transitive fluctuation.

[0073] Furthermore, e^(-processed time difference) is the attenuation mapping. As the time difference increases → the exponential value decays → the transfer coefficient decreases, and a continuous coefficient space of (0, 1] is naturally formed. Example: 0.3-second difference → e^(-0.3) ≈ 0.74 (strong transfer), 3-second difference → e^(-3) ≈ 0.05 (weak transfer)

[0074] In summary, the transfer speed is objectively reflected by the response time difference, and the exponential mapping avoids subjective empirical assignment. If unit B responds 2 seconds faster than unit C → a higher coefficient is automatically assigned. At the same time, coordinated regulation accurately distributes (eliminates overshoot / undershoot). For a strong transfer relationship (coefficient > 0.7), 95% of the adjustment amount of the source unit is executed, and for a weak transfer relationship (coefficient < 0.2), only 20% of the preventive fine-tuning is started. Units in the same area obtain different coefficients due to differences in concrete foundations. Furthermore, the exponential decay characteristic captures the transfer speed, and when the transfer is fast (time difference < 5 seconds), an advanced compensation is automatically injected; the guide vane adjustment instruction is executed half a cycle in advance to block the energy transfer chain.

[0075] As Figure 8 shown, in one embodiment, S5 obtains the cooperative suppression control strategy for the i-th unit and the adjacent unit of the i-th unit according to the real-time vibration amplitude and transfer coefficient of the i-th unit, including:

[0076] S51. Obtain the first suppression instruction for the i-th unit according to the real-time vibration amplitude of the i-th unit, where the first suppression instruction includes a first adjustment item and first adjustment data corresponding to the first adjustment item;

[0077] S52. Obtain the second suppression instruction for the adjacent unit of the i-th unit, where the second suppression instruction includes a second adjustment item and second adjustment data corresponding to the second adjustment item. Among them, the second adjustment item is the same as the first adjustment item, and the second adjustment data is obtained through the transfer coefficient of the adjacent unit of the i-th unit and the first adjustment data;

[0078] S53. A coordinated suppression control strategy is formed based on the first suppression command of the i-th unit and the second suppression command of the adjacent units of the i-th unit.

[0079] In this embodiment, it should be noted that in S51, the first suppression command is dynamically generated based on the real-time vibration amplitude of the i-th unit. This process converts the vibration intensity into precise adjustment parameters through a nonlinear mapping mechanism: if high-frequency pressure pulsation or vortex band resonance characteristics are detected, high-intensity adjustment is triggered (such as significantly reducing the load to destroy the vortex band structure); if it is a low-frequency small-amplitude vibration, a gradual fine-tuning is adopted (such as adjusting the guide vane opening by 0.5%).

[0080] For example, when Unit A experiences vortex-dominated vibration in the tailrace tube, the vibration mode is automatically decoupled, generating a combined command of "guide vane opening reduced by X% + load reduced by Y%" (the X / Y value is dynamically calculated based on the vibration energy gradient), instead of triggering with a fixed threshold. This adaptive mechanism completely avoids under-adjustment (continuous vibration) or over-adjustment (loss of power generation efficiency) caused by empiricism.

[0081] In S52, the first suppression command is spatially corrected using the transmission coefficient to generate a second suppression command for adjacent units. The adjustment items are strictly consistent with the source unit (e.g., guide vane opening adjustment), but the adjustment amount is dynamically scaled using the transmission coefficient: strong transmission relationship (transmission coefficient > 0.7) adopts an intervention intensity close to that of the source unit (e.g., when unit B is subjected to 90% transmission effect, the source unit's adjustment amount is executed at 95%); weak transmission relationship (transmission coefficient < 0.2) only initiates preventive fine-tuning (e.g., the adjustment amount of unit C is reduced to 20% of the source unit's). The core physical intervention mechanism is phase compensation. When the transmission time difference is less than a preset critical value (reflecting rapid transmission), a phase advance compensation term is automatically injected, causing the adjustment action to be executed 1 / 2 vibration cycle in advance. For example, when unit B receives the command from unit A, it predicts the direction of vibration wave transmission and counteracts the energy flow in the opposite direction before the vibration energy arrives, physically blocking the transmission chain.

[0082] In S53, all suppression instructions are integrated and spatiotemporal constraints can be injected. Instructions are sorted by direction (e.g., A→B→C). At the same time, downstream instructions are executed with a delay of half the transmission time difference (e.g., unit B is executed 2 seconds later than unit A). Finally, the transmission coefficient is monitored in real time after execution. If the vibration of a certain unit does not decay (e.g., unit C continues to vibrate after adjustment), a second collaborative iteration is automatically triggered.

[0083] A vibration collaborative suppression control system for multi-unit hydropower stations is also provided, the system comprising:

[0084] The data acquisition module is used to acquire multiple units set sequentially, and to acquire the vibration data sequence of each unit in the previous monitoring cycle of the current monitoring cycle;

[0085] The first data processing module is used to obtain the i-th target time period representing the increase in vibration intensity of the i-th unit based on the vibration data sequence of the i-th unit, and to obtain the first time point of the i-th target time period and use it as the i-th target time point.

[0086] The second data processing module is used to obtain the vibration data sequence of the adjacent units of the i-th unit and use it as a comparison data sequence, and to obtain the i-th comparison time period representing the increase in vibration intensity of the adjacent units based on the comparison data sequence after the i-th target time point, and to obtain the first time point of the i-th comparison time period and use it as the i-th comparison time point of the adjacent units.

[0087] The third data processing module is used to obtain the transmission coefficient between the i-th unit and each of the i-th unit's adjacent units based on the i-th target time point and the i-th comparison time point of each of the i-th unit's adjacent units;

[0088] The suppression control module is used to obtain the real-time vibration amplitude of the i-th unit and obtain the cooperative suppression control strategy of the i-th unit and its adjacent units based on the real-time vibration amplitude and transmission coefficient of the i-th unit.

[0089] In one embodiment, the first data processing module is further configured to: obtain a first change between the vibration amplitude of the next vibration and the previous vibration amplitude in the vibration data sequence of the i-th unit; divide the vibration data sequence of the i-th unit into multiple continuously increasing data segments, wherein each continuously increasing data segment contains at least two vibration amplitudes, and the first change between each adjacent vibration amplitude in each continuously increasing data segment is greater than zero; obtain the continuously increasing data segment containing the most vibration amplitudes and take the continuous time range corresponding to the continuously increasing data segment as the i-th target time period.

[0090] In one embodiment, the second data processing module is further configured to: take the comparison data sequence after the i-th target time point as the i-th valid data sequence, and obtain the second change between the next vibration amplitude and the previous vibration amplitude in the i-th valid data sequence; divide the i-th valid data sequence into multiple continuous lifting data segments, wherein each continuous lifting data segment contains at least two vibration amplitudes, and the second change between each adjacent vibration amplitude in each continuous lifting data segment is greater than zero; obtain the continuous lifting data segment containing the most vibration amplitudes and take the continuous time range corresponding to the continuous lifting data segment as the i-th comparison time period.

[0091] In one embodiment, the third data processing module is further configured to: obtain a standard transmission time difference range, and obtain a minimum transmission time gap and a maximum transmission time gap based on the standard transmission time difference range; and obtain the transmission coefficient between the i-th unit and the j-th adjacent unit of the i-th unit based on the i-th target time point, the i-th comparison time point of the j-th adjacent unit of the i-th unit, the minimum transmission time gap, and the maximum transmission time gap.

[0092] In this embodiment, it should be noted that the specific operation method of the vibration coordinated suppression control system for the above-mentioned multi-unit hydropower station has been described in detail in the embodiments of the vibration coordinated suppression control method for multi-unit hydropower stations, and will not be elaborated here.

[0093] The preferred embodiments of the present disclosure have been described in detail above with reference to the accompanying drawings. However, the present disclosure is not limited to the specific details of the above embodiments. Within the scope of the technical concept of the present disclosure, various simple modifications can be made to the technical solutions of the present disclosure, and these simple modifications all fall within the protection scope of the present disclosure.

[0094] It should also be noted that the various specific technical features described in the above embodiments can be combined in any suitable manner without contradiction. To avoid unnecessary repetition, this disclosure will not describe the various possible combinations separately.

[0095] Furthermore, various different embodiments of this disclosure can be combined in any way, as long as they do not violate the spirit of this disclosure, they should also be regarded as the content disclosed in this disclosure.

[0096] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention, and they should all be covered within the scope of the claims and specification of the present invention.

Claims

1. A method for coordinated vibration suppression and control in a multi-unit hydropower station, characterized in that, include: Acquire multiple units set sequentially, and acquire the vibration data sequence of each unit in the previous monitoring cycle of the current monitoring cycle; Based on the vibration data sequence of the i-th unit, obtain the i-th target time period to represent the increase in vibration intensity of the i-th unit, and obtain the first time point of the i-th target time period as the i-th target time point; Obtain the vibration data sequence of the adjacent units of the i-th unit and use it as the comparison data sequence. Based on the comparison data sequence after the i-th target time point, obtain the i-th comparison time period to represent the increase in vibration intensity of the adjacent units. Obtain the first time point of the i-th comparison time period and use it as the i-th comparison time point of the adjacent units. Obtain the standard transmission time difference range, and based on the standard transmission time difference range, obtain the minimum transmission time gap and the maximum transmission time gap; The transmission coefficient between the i-th unit and the j-th adjacent unit of the i-th unit is obtained based on the i-th target time point, the i-th comparison time point of the j-th adjacent unit of the i-th unit, the minimum transmission time gap, and the maximum transmission time gap; The transfer coefficient between the i-th unit and its j-th adjacent unit is expressed as: ;in, Let be the transfer coefficient between the i-th unit and its j-th adjacent unit. For the i-th comparison time point of the j-th adjacent unit of the i-th unit, For the i-th target time point, To minimize the transmission time gap, This is the maximum transmission time interval; Obtain the real-time vibration amplitude of the i-th unit; The first suppression command for the i-th unit is obtained based on the real-time vibration amplitude of the i-th unit. The first suppression command includes a first adjustment item and first adjustment data corresponding to the first adjustment item. The second suppression command for the adjacent units of the i-th unit is obtained. The second suppression command includes a second adjustment item and second adjustment data corresponding to the second adjustment item. The second adjustment item is the same as the first adjustment item. The second adjustment data is obtained through the transfer coefficient of the adjacent units of the i-th unit and the first adjustment data. A coordinated suppression control strategy is formed based on the first suppression command of the i-th unit and the second suppression command of the adjacent units of the i-th unit.

2. The vibration coordinated suppression and control method for multi-unit hydropower stations according to claim 1, characterized in that, The step of obtaining the i-th target time period representing the increase in vibration intensity of the i-th unit based on the vibration data sequence of the i-th unit includes: Obtain the first change between the vibration amplitude of the next vibration and the previous vibration amplitude in the vibration data sequence of the i-th unit; The vibration data sequence of the i-th unit is divided into multiple continuously increasing data segments, wherein each continuously increasing data segment contains at least two vibration amplitudes, and the first change between each adjacent vibration amplitude in each continuously increasing data segment is greater than zero. Obtain the continuous lifting data segment containing the most vibration amplitudes and use the continuous time range corresponding to this continuous lifting data segment as the i-th target time period.

3. The vibration coordinated suppression and control method for multi-unit hydropower stations according to claim 1, characterized in that, The process of obtaining the i-th comparison time period, which represents the increase in vibration intensity of adjacent units, based on the comparison data sequence after the i-th target time point includes: The comparison data sequence after the i-th target time point is taken as the i-th valid data sequence, and the second change between the next vibration amplitude and the previous vibration amplitude in the i-th valid data sequence is obtained. The i-th valid data sequence is divided into multiple continuously rising data segments, wherein each continuously rising data segment contains at least two vibration amplitudes, and the second change between each adjacent vibration amplitude in each continuously rising data segment is greater than zero. Obtain the continuous lifting data segment containing the most vibration amplitudes and use the continuous time range corresponding to this continuous lifting data segment as the i-th comparison time period.

4. A vibration collaborative suppression control system for a multi-unit hydropower station, characterized in that, The system is used to implement the vibration coordinated suppression and control method for multi-unit hydropower stations as described in any one of claims 1 to 3, the system comprising: The data acquisition module is used to acquire multiple units set sequentially, and to acquire the vibration data sequence of each unit in the previous monitoring cycle of the current monitoring cycle; The first data processing module is used to obtain the i-th target time period representing the increase in vibration intensity of the i-th unit based on the vibration data sequence of the i-th unit, and to obtain the first time point of the i-th target time period and use it as the i-th target time point. The second data processing module is used to obtain the vibration data sequence of the adjacent units of the i-th unit and use it as a comparison data sequence, and to obtain the i-th comparison time period representing the increase in vibration intensity of the adjacent units based on the comparison data sequence after the i-th target time point, and to obtain the first time point of the i-th comparison time period and use it as the i-th comparison time point of the adjacent units. The third data processing module is used to obtain the transmission coefficient between the i-th unit and each of the i-th unit's adjacent units based on the i-th target time point and the i-th comparison time point of each of the i-th unit's adjacent units; The suppression control module is used to obtain the real-time vibration amplitude of the i-th unit and obtain the cooperative suppression control strategy of the i-th unit and its adjacent units based on the real-time vibration amplitude and transmission coefficient of the i-th unit.

5. The vibration collaborative suppression control system for a multi-unit hydropower station according to claim 4, characterized in that, The first data processing module is also used for: Obtain the first change between the vibration amplitude of the next vibration and the previous vibration amplitude in the vibration data sequence of the i-th unit; The vibration data sequence of the i-th unit is divided into multiple continuously increasing data segments, wherein each continuously increasing data segment contains at least two vibration amplitudes, and the first change between each adjacent vibration amplitude in each continuously increasing data segment is greater than zero. Obtain the continuous lifting data segment containing the most vibration amplitudes and use the continuous time range corresponding to this continuous lifting data segment as the i-th target time period.

6. The vibration collaborative suppression control system for a multi-unit hydropower station according to claim 4, characterized in that, The second data processing module is also used for: The comparison data sequence after the i-th target time point is taken as the i-th valid data sequence, and the second change between the next vibration amplitude and the previous vibration amplitude in the i-th valid data sequence is obtained. The i-th valid data sequence is divided into multiple continuously rising data segments, wherein each continuously rising data segment contains at least two vibration amplitudes, and the second change between each adjacent vibration amplitude in each continuously rising data segment is greater than zero. Obtain the continuous lifting data segment containing the most vibration amplitudes and use the continuous time range corresponding to this continuous lifting data segment as the i-th comparison time period.

7. The vibration collaborative suppression control system for a multi-unit hydropower station according to claim 4, characterized in that, The third data processing module is also used for: Obtain the standard transmission time difference range, and based on the standard transmission time difference range, obtain the minimum transmission time gap and the maximum transmission time gap; The transmission coefficient between the i-th unit and the j-th adjacent unit of the i-th unit is obtained based on the i-th target time point, the i-th comparison time point of the j-th adjacent unit of the i-th unit, the minimum transmission time gap, and the maximum transmission time gap.

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