Pump turbine phase resonance risk identification method, equipment, medium and product

Abstract

The invention discloses a pump turbine phase resonance risk identification method and device, a medium and a product, and relates to the field of hydroelectric generation. The method comprises the following steps: firstly, carrying out a pressure pulsation test on the water-turbine generator set to determine each-order dominant frequency of an excitation source; calculating the wavelength of a pressure wave corresponding to each order of dominant frequency according to the working condition of the pump turbine; according to the working condition of the pump turbine, the position difference of two pressure wave transmission during two adjacent excitation is calculated; substituting the wavelength of the pressure wave corresponding to the dominant frequency of each order and the position difference under different pump turbine working conditions into a phase resonance risk coefficient calculation formula, and calculating to obtain a phase resonance risk coefficient of the pressure wave corresponding to the dominant frequency of each order; and comparing the phase resonance risk coefficient of the pressure wave corresponding to the dominant frequency of each order with the risk judgment coefficient, and identifying the harmonic order with the phase resonance risk. By adopting the method, the judgment precision of phase resonance can be improved, and the application range of the phase resonance judgment method is expanded.

Description

Technical Field

[0001] The present application relates to the technical field of hydropower generation, and in particular to a method, equipment, medium and product for identifying phase resonance risks of a pump turbine. Background Art

[0002] In the design and operation of pump turbines used in hydropower station units, dynamic-static interference and phase resonance are common problems, which may cause the vibration of the unit to intensify, affect the service life of the unit, and even cause safety accidents. Phase resonance is a simple hydraulic phenomenon, which is mainly caused by the propagation and superposition of pressure waves generated by dynamic-static interference in the volute and high-pressure side pipeline. In particular, when the number of blades and guide vanes is not properly matched, the phase of the pressure wave may be the same, resulting in the superposition of amplitudes and the formation of high-intensity hydraulic excitation force. This excitation force will not only cause the vibration of the pressure steel pipe and generate high-decibel noise, but also cause high-intensity pressure pulsation and plant vibration, which seriously threatens the safe operation of the power station. At present, domestic and foreign experts and scholars have conducted research on this, but the research results are only applicable to conventional turbines, and cannot distinguish the frequency components of pressure waves that may cause phase resonance risks. Summary of the invention

[0003] The purpose of this application is to provide a method, device, medium and product for identifying the risk of phase resonance of a pump-turbine so as to improve the accuracy of determining phase resonance and expand the scope of application of the phase resonance determination method.

[0004] To achieve the above objectives, this application provides the following solutions.

[0005] In a first aspect, the present application provides a method for identifying phase resonance risk of a pump-turbine, comprising:

[0006] Carry out pressure pulsation test on hydro-generator set to determine the dominant frequencies of each order of excitation source;

[0007] Calculate the pressure wave wavelength corresponding to each order of dominant frequency according to the pump turbine operating conditions;

[0008] According to the pump-turbine operating conditions, the position difference between the two pressure waves transmitted when two adjacent excitations occur is calculated;

[0009] Substitute the pressure wave wavelength corresponding to each order of dominant frequency and the position difference under different pump-turbine operating conditions into the phase resonance risk coefficient calculation formula to calculate the phase resonance risk coefficient of the pressure wave corresponding to each order of dominant frequency;

[0010] The phase resonance risk coefficient of the pressure wave corresponding to each order of dominant frequency is compared with the risk determination coefficient to identify the harmonic order with phase resonance risk.

[0011] Optionally, the pressure pulsation test on the hydro-generator set to determine the dominant frequencies of each order of the excitation source specifically includes:

[0012] Differential pressure sensors are arranged at the measuring points of the volute inlet of the hydro-turbine generator set, the +X and +Y directions between the impeller and the movable guide vane, and the +X and +Y directions between the top cover and the impeller, and the collected pressure pulsation signals are connected to the data acquisition system, and the signals are Fourier transformed to obtain the spectrum diagram;

[0013] The frequency spectra at different measuring points are analyzed to obtain the main dominant frequencies of the pressure pulsation between the runner and the movable guide vane and at the volute inlet, which are used as the dominant frequencies of each order of the excitation source.

[0014] Optionally, the step of calculating the pressure wave wavelength corresponding to each order of dominant frequency according to the operating condition of the pump turbine specifically includes:

[0015] When the pump turbine is in pumping condition, the formula λ k =a a / f k Calculate the dominant frequency f of each order k The corresponding pressure wave wavelength λ k ; where a a is the pressure wave transmission speed in counterclockwise condition; f k = k·f n ;f n is the unit rotation frequency; k is the harmonic order;

[0016] When the pump turbine is in turbine operation, the formula λ k =a c / f k Calculate the dominant frequency f of each order k The corresponding pressure wave wavelength λ k ; where a c is the pressure wave transmission speed in clockwise condition.

[0017] Optionally, the calculating, according to the pump-turbine operating condition, the position difference between two pressure waves transmitted when two adjacent excitations occur, specifically includes:

[0018] When the pump turbine is in pumping condition, the formula is used. Calculate the transmission position difference ΔS of adjacent excitation pressure waves in counterclockwise condition a , as the position difference ΔS between the two pressure waves when two adjacent excitations occur; where Δg a is the number of guide vane excitation intervals when rotating counterclockwise; Z g is the number of active guide vanes; D sp is the equivalent diameter of the volute; Z r is the number of runner blades; (Z r ,Zg ) is Z r and Z g The greatest common divisor of;

[0019] When the pump turbine is in turbine operation, the formula Calculate the transmission position difference ΔS of adjacent excitation pressure waves in clockwise condition c , as the position difference ΔS between the two pressure waves when two adjacent excitations occur; where Δg c It is the number of guide vane excitation intervals when rotating clockwise.

[0020] Optionally, the wavelength of the pressure wave corresponding to each order dominant frequency and the position difference under different pump-turbine operating conditions are substituted into the phase resonance risk coefficient calculation formula to calculate the phase resonance risk coefficient of the pressure wave corresponding to each order dominant frequency, specifically including:

[0021] The dominant frequencies f k The corresponding pressure wave wavelength λ k Substitute the position difference ΔS under different pump-turbine operating conditions into the phase resonance risk coefficient calculation formula Calculate the dominant frequency f of each order k The corresponding pressure wave phase resonance risk factor RF k ; where [] is the rounding symbol.

[0022] Optionally, comparing the phase resonance risk coefficient of the pressure wave corresponding to each order of dominant frequency with the risk determination coefficient to identify the harmonic order with phase resonance risk specifically includes:

[0023] The dominant frequencies f k The corresponding pressure wave phase resonance risk factor RF k Compared with the risk determination coefficient σ; when RF k <σ, the corresponding harmonic order k is determined to be the harmonic order k' with a phase resonance risk.

[0024] Optionally, the pump-turbine phase resonance risk identification method further includes:

[0025] According to the harmonic order k' with the risk of phase resonance, the frequency component f is k′ Perform frequency staggered design.

[0026] In a second aspect, the present application provides a computer device, comprising: a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the computer program to implement the pump-turbine phase resonance risk identification method.

[0027] In a third aspect, the present application provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the method for identifying the risk of phase resonance of a pump-turbine.

[0028] In a fourth aspect, the present application provides a computer program product, including a computer program, which implements the pump-turbine phase resonance risk identification method when executed by a processor.

[0029] According to the specific embodiments provided in this application, this application discloses the following technical effects.

[0030] The present application provides a method, device, medium and product for identifying the risk of phase resonance of a pump turbine. Based on the law and sequence of pressure wave excitation, the application considers that the excitation intervals of the runner blades and guide vanes are different in turbine working conditions and pump working conditions, and therefore the position difference and phase difference of the excited pressure waves propagating to the volute are also different. Therefore, the turbine working conditions and pump working conditions are considered separately, which improves the accuracy of determining the phase resonance under the two different working conditions. In addition, for the long and short blade units that have emerged in recent years, considering that the pressure pulsation between the runner and the guide vanes often presents multi-component frequency components, the present application considers the possibility of phase resonance caused by pressure waves of different harmonic orders, i.e., different frequency components, which is not only applicable to traditional turbines, but also to new units, expanding the scope of use of the phase resonance determination method. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0032] Figure 1 A schematic diagram of a process flow of a method for identifying phase resonance risk of a pump-turbine according to the present application;

[0033] Figure 2 Schematic diagram of the volute transmission of pressure pulsation between the runner and the movable guide vanes. DETAILED DESCRIPTION

[0034] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0035] The present application proposes a method, device, medium and product for identifying the risk of phase resonance of a pump-turbine to improve the accuracy of determining phase resonance and expand the scope of application of the phase resonance determination method.

[0036] In order to make the above-mentioned objects, features and advantages of the present application more obvious and easy to understand, the present application is further described in detail below in conjunction with the accompanying drawings and specific implementation methods.

[0037] In an exemplary embodiment, Figure 1 As shown, a method for identifying phase resonance risk of a pump-turbine is provided, comprising the following steps 1 to 5.

[0038] Step 1: Conduct pressure pulsation test on the hydro-generator set to determine the dominant frequencies of each order of the excitation source.

[0039] The installation and positioning procedure of the pump turbine is to first determine the installation center line and elevation point of the turbine based on the measurement reference point of the hydraulic structure. The center line of the turbine is represented by the horizontal plane coordinates X and Y axes. The Y axis is the water flow direction line of the upstream and downstream of the unit, the upstream side is +Y direction, and the downstream side is -Y direction. The X axis is the horizontal direction line running through the plant, the left side is +X direction, and the right side is -X direction. The intersection of the X and Y axes is the center point of the turbine, and the vertical line through the center point is the vertical center line of the turbine. When the present application carries out a pressure pulsation test on the hydro-generator set, a measuring point is arranged at the +X direction of the volute inlet, two measuring points in the +X and +Y directions between the runner and the movable guide vane (referred to as the guide vane), and two measuring points in the +X and +Y directions between the top cover and the runner, for a total of 5 measuring points. Of course, in actual applications, other measuring points can also be arranged at other excitation sources, such as measuring points at the plant volute layer, turbine layer, busbar layer and generator layer. The volute layer, turbine layer, busbar layer and generator layer are the structures of the hydropower plant from bottom to top. The measuring points between the top cover and the runner, between the runner and the movable guide vane, and the volute inlet are the measuring points of the runner. Usually, the pressure pulsation in the runner is the excitation source of the plant vibration. The arrangement of measuring points on the runner can understand the amplitude-frequency characteristics of the vibration source.

[0040] Differential pressure sensors are arranged at the measuring points of the volute inlet, +X and +Y directions between the impeller and the movable guide vane, and +X and +Y directions between the top cover and the impeller of the hydro-turbine generator set. The collected pressure pulsation signal (current value) is connected to the data acquisition system, and the corresponding spectrum diagram can be obtained by Fourier transforming the signal. Then, the spectrum diagrams at different measuring points are analyzed to obtain the main dominant frequency of the pressure pulsation at each measuring point. The main dominant frequency is the main frequency, because the pressure pulsation between the impeller and the movable guide vane is the main hydraulic factor that produces dynamic and static interference (from an optical point of view, interference will produce waves). The dominant frequency of each measuring point is obtained here mainly to determine whether the pressure pulsation (i.e., pressure wave) between the impeller and the movable guide vane is transmitted upstream and downstream. Therefore, it is necessary to measure multiple main dominant frequencies of the pressure pulsation between the impeller and the movable guide vane and the volute inlet, as the dominant frequencies of each order of the excitation source, denoted as f k = k·f n ; where f n is the unit rotation frequency; k is the harmonic order; therefore, it can also be called the k-order dominant frequency f k .

[0041] The main dominant frequencies of the measured pressure pulsation are compared and analyzed to find out the same frequency components at the volute inlet measuring point and between the runner and the movable guide vane, that is, the pressure wave transmitted upstream (towards the volute) by the dynamic and static interference pressure pulsation (pressure wave) between the runner and the movable guide vane.

[0042] Specifically, the frequency spectrum of the time domain signal of each measuring point can be obtained after Fourier transformation. From the frequency spectrum, it can be seen that the volute inlet measuring point and the impeller and the movable guide vane have the same dominant frequency component (main frequency), so it can be determined that the pressure pulsation between the impeller and the movable guide vane is transmitted upstream to the volute. The pressure wave is the pressure pulsation vibration mode.

[0043] According to the dynamic-static interference pressure pulsation generation mechanism, the dynamic-static interference pressure wave between the runner and the movable guide vane is the superposition of the pressure pulsations of the flow frequencies of blades of different orders. Combined with the number of runner blades and the number of movable guide vanes (here, the number of runner blades is 9 and the number of movable guide vanes is 20 as an example), the phase resonance risk analysis is carried out by taking the counterclockwise rotation of the runner (water pump working condition) as an example. For the hydro-generator set, the guide vanes are fixed, and the runner rotates counterclockwise for the water pump working condition, and the runner rotates clockwise for the water turbine working condition.

[0044] like Figure 2As shown, it is assumed that at t=0, during the rotation of the runner, the 1# (No. 1) runner blade (referred to as the blade) is at the 0° position and the relative position with the tail of the 1# active guide vane reaches the minimum value (also the position where the head of all blades is closest to the tail of the guide vane), and a pressure wave is excited here, which is assumed to be the first "excitation". The runner rotates counterclockwise. After a period of △t, the 1# runner blade rotates to the 2° position. During this period, the 5# runner blade rotates from the 160° position to the 162° position. At this time, among all the relative positions of the 9 runner blades and the 20 guide vanes, the 5# runner blade is closest to the 10# guide vane. At this time, an "excitation" also occurs. At the same time as the new "excitation" occurs, the pressure wave of the previous "excitation" has begun to propagate in the flow channel at a wave speed a. Similarly, after another period of △t, the 1# runner blade rotates to the 4° position, and the 9# blade and the 19# blade are "excited" at the 324° position. During the rotation of the impeller blade #1 from the guide vane #1 to the guide vane #2 (rotation angle 18°), blades #1 to #9 are "excited" once respectively. During one rotation of the impeller, there are a total of 180 "excitations", with each impeller blade being excited 20 times and each guide vane being excited 9 times.

[0045] When the runner rotates clockwise (turbine operating condition), similar excitation rules can be obtained, as shown in Table 1 below.

[0046] Table 1 Law of pressure pulsation excitation in bladeless area of ​​9+20 cascade combination

[0047]

[0048] In Table 1, when the impeller rotates counterclockwise, it is a water pump working condition, and when the impeller rotates clockwise, it is a water turbine working condition. The blade excitation interval means that after blade No. 1 and guide vane No. 1 are excited, blade No. 5 and guide vane No. 10 begin to be excited after a period of △t, then the blade excitation interval is 5-1=4; the guide vane excitation interval is the same. The guide vane is fixed, and the impeller rotates. Counterclockwise (clockwise) refers to the rotation direction of the impeller. Since the blades and guide vanes are numbered, the guide vanes excited are different when the impeller rotates counterclockwise and clockwise, and the corresponding excitation intervals are also different.

[0049] For the uniform distribution of runner blades and water guide blades (i.e. guide vanes), the following rules can be summarized from Table 1 regarding the relevant parameters:

[0050]

[0051] Z r =(Δr a +Δr c )·(Z r , Z g ) (2)

[0052] Z g =(Δg a +Δg c )·(Z r , Z g ) (3)

[0053]

[0054] Among them, Z g is the number of active guide vanes; Z r is the number of impeller blades; Δθ is the excitation interval step length, in radians (rad); Δr a Δg is the number of intervals of excitation of the impeller blades when rotating counterclockwise; a Δr is the number of guide vane excitation intervals when rotating counterclockwise; c Δg is the number of excitation intervals of the impeller blades when rotating clockwise; c is the number of excitation intervals of the guide vane when rotating clockwise; Δt is the duration of the excitation interval, in seconds; ω n is the angular velocity of the wheel, rad / s; f n is the wheel rotation frequency, i.e. the unit rotation frequency, in Hz; (Z r , Z g ) is Z r and Z g The greatest common divisor of ; [] is the integer symbol (rounding off).

[0055] For the counterclockwise condition, formula (8) is the time difference between two adjacent "excitations". At the time of the second excitation, the pressure wave of the first excitation has propagated outward along the flow channel. Assume that the wave speed of the pressure wave of the first excitation transmitted in the counterclockwise direction is a a ,for Figure 2 For the simplified model shown, the position difference of the two pressure waves when the second "excitation" occurs is:

[0056]

[0057] The angular deviation (radian) relative to the equivalent diameter of the volute is:

[0058]

[0059] Similarly, in the clockwise case, the position difference is:

[0060]

[0061] The angular deviation (radian) relative to the equivalent diameter of the volute is:

[0062]

[0063] Among them, ΔS aΔS is the transmission position difference of adjacent excitation pressure waves in counterclockwise working condition; c is the transmission position difference of adjacent excitation pressure waves in clockwise condition; Δθ a is the phase difference of adjacent excited pressure waves in counterclockwise condition; Δθ c is the phase difference of adjacent excited pressure waves in clockwise condition; a a is the pressure wave transmission speed in counterclockwise working condition (referred to as wave speed); a c D is the pressure wave transmission speed in clockwise condition. sp The above formulas (1) to (12) are summarized based on the excitation law of pressure waves. In engineering practice, a a ≈a c .

[0064] The pressure pulsation between the runner and the movable guide vane is the superposition of the pressure pulsations of the flow frequencies of the blades of different orders. When the excitation interval ΔS (clockwise, ΔS = ΔS) with a relatively fixed position difference is faced, c ; Counterclockwise, take ΔS=ΔS a ), the ratio of the wavelength to the spacing of pressure pulsation components of different frequencies is different, and the amplification factor is significantly different after superposition in the volute. When ΔS is an integer multiple of the wavelength λ of a certain order of harmonics, the peaks and troughs of the harmonics excited at each measuring point are close to superposition, and the pressure pulsation amplitude of the volute is amplified by a large factor, resulting in phase resonance.

[0065] Formulas (1) to (12) are derived from the excitation law fitting formulas based on pressure pulsation tests on different combinations of multiple sets of runner blades and guide vane cascades. Phase resonance occurs when the excitation interval is an integer multiple of the wavelength. Therefore, the judgment formula (13) is introduced. When the following formula (13) is established, the determined k-order blade current frequency harmonic has a phase resonance risk.

[0066]

[0067] Among them, RF k is the phase resonance risk coefficient; σ is the risk determination coefficient, which is usually less than or equal to 0.2. ΔS is the position difference of adjacent excitation pressure waves, that is, the position difference of two pressure waves when two adjacent excitations occur; clockwise (turbine working condition), ΔS=ΔS c ; Counterclockwise (water pump working condition), take ΔS=ΔS a . k is the wavelength of the water pressure wave at the k-order blade frequency, that is, the dominant frequency f of each order k The corresponding pressure wave wavelength; [ ] is the integer symbol (rounded off). That is, when the phase resonance risk factor RF of the k-order blade flow frequency harmonic k When it is less than the risk determination coefficient σ, it is determined that the k-order blade overcurrent frequency harmonic has a phase resonance risk.

[0068] Step 2: Calculate the pressure wave wavelength corresponding to each order of dominant frequency according to the pump-turbine operating conditions.

[0069] The signals obtained by the data acquisition system are all time domain signals. In order to find out the propagation direction of pressure pulsation and its frequency characteristics, it is necessary to perform Fourier transform on the signal to obtain the frequency signal. The dominant frequency (main frequency) of each measuring point can be intuitively seen from the transformed spectrum diagram. Usually, the main frequency component of the pressure pulsation between the runner and the guide vane is the blade flow frequency and its multiple frequency, which is the source of vibration of the unit and the plant.

[0070] When the pump turbine is in pumping condition, the formula λ k =a a / f k Calculate the dominant frequency f of each order k The corresponding pressure wave wavelength λ k . Among them a a is the pressure wave transmission speed in counterclockwise condition; f k = k·f n ;f n is the unit rotation frequency; k is the harmonic order.

[0071] When the pump turbine is in turbine operation, the formula λ k =ac / f k Calculate the dominant frequency f of each order k The corresponding pressure wave wavelength λ k ; where a c is the pressure wave transmission speed in clockwise condition.

[0072] Step 3: Calculate the position difference between the two pressure waves transmitted when two adjacent excitations occur according to the pump-turbine operating conditions.

[0073] Since the impellers rotate in different directions in turbine and pump conditions, the blade excitation interval and guide vane excitation interval are different, and the distance difference produced by the two excitations is different, so the determination of phase resonance is also different.

[0074] When the pump turbine is in pumping condition, the formula is used. Calculate the transmission position difference ΔS of adjacent excitation pressure waves in counterclockwise condition a , as the position difference ΔS between the two pressure waves when two adjacent excitations occur. Where Δg a is the number of guide vane excitation intervals when rotating counterclockwise; Z g is the number of active guide vanes; D sp is the equivalent diameter of the volute; Z r is the number of runner blades; (Z r ,Z g) is Z r and Z g The greatest common divisor of .

[0075] When the pump turbine is in turbine operation, the formula Calculate the transmission position difference ΔS of adjacent excitation pressure waves in clockwise condition c , as the position difference ΔS between the two pressure waves when two adjacent excitations occur. Where Δg c It is the number of guide vane excitation intervals when rotating clockwise.

[0076] Step 4: Substitute the wavelength of the pressure wave corresponding to each order of dominant frequency and the position difference under different pump-turbine operating conditions into the phase resonance risk coefficient calculation formula to calculate the phase resonance risk coefficient of the pressure wave corresponding to each order of dominant frequency.

[0077] The dominant frequencies f k The corresponding pressure wave wavelength λ k Substitute the position difference ΔS under different pump-turbine operating conditions into the phase resonance risk coefficient calculation formula Calculate the dominant frequency f of each order k The corresponding pressure wave phase resonance risk factor RF k ; where [] is the rounding symbol.

[0078] Step 5: Compare the phase resonance risk coefficient of the pressure wave corresponding to each order of dominant frequency with the risk determination coefficient to identify the harmonic order with phase resonance risk.

[0079] The dominant frequencies f k The corresponding pressure wave phase resonance risk factor RF k Compared with the risk determination coefficient σ; when RF k <σ, the corresponding harmonic order k is determined to be the harmonic order k' with phase resonance risk, then f k′ This is a frequency component that has a risk of phase resonance.

[0080] For a newly designed power station, the frequency component f with phase resonance risk calculated in step 5 should be calculated during the turbine and powerhouse design stage. k′ Consider staggered frequency design.

[0081] In order to verify the accuracy of the phase resonance risk identification method of the present application, for the power station that has been put into operation, the phase resonance risk coefficient RF calculated by formula (13) is kField tests were carried out in power stations with a value less than σ = 0.2. Differential pressure sensors and acceleration sensors were arranged in the +X and +Y directions between the top cover and the runner, in the +X and +Y and -X and -Y directions of the volute inlet, in the volute layer of the plant, in the turbine layer, in the bus layer and in the generator layer. The signals of the measuring points were connected to the data acquisition system, and it was found that their vibration response and noise were usually large. After Fourier transformation, it can be obtained that the dominant frequency of the measuring point with a large vibration response includes the k'-order blade flow frequency corresponding to the phase resonance risk coefficient calculated by formula (13) of the present application being less than 0.2, which shows the effectiveness of the phase resonance risk identification method of the present application. Based on this, targeted treatment measures can be proposed. For example, according to the harmonic order k' with phase resonance risk, the frequency component f k′ Conduct frequency mismatch design. For power plants with phase resonance risks, the natural frequency of the plant can be changed by changing the plant structure (such as thickening the floor or changing the floor material). Or the vibration source frequency can be changed by changing the shape of the blades to achieve the purpose of frequency mismatch.

[0082] Compared with the prior art, the advantage of the present application is that the phase resonance risk identification method based on the pressure wave excitation law and excitation sequence not only distinguishes the differences in harmonics of different orders of the flow frequency of the impeller blades after transmission in the volute, but also distinguishes the differences in phase resonance between water pump operating conditions and water turbine operating conditions, thereby improving the accuracy of phase resonance determination and expanding the scope of application of the phase resonance determination method.

[0083] Specifically, by λ k =a / f k It can be seen that the wavelengths of pressure waves of different frequencies are different. It can be seen from the phase resonance determination formula (13) that the phase resonance risk identification method of the present application takes into account the possibility of phase resonance caused by pressure waves of different harmonic orders, i.e. different frequency components. In recent years, the pressure pulsation between the runner and the guide vane of the newly emerged long and short blade units often presents multi-component frequency components. Therefore, the method of the present application is not only applicable to traditional turbines, but also to new units, which expands the scope of application of the phase resonance determination method.

[0084] It can be seen from the pressure wave excitation law derived in this application that the excitation intervals of the impeller blades and guide vanes in the turbine operating condition and the water pump operating condition are different. Therefore, the position difference and phase difference of the excited pressure waves propagating to the volute are also different (assuming the wave speed is the same). This application considers the two operating conditions separately, which can improve the accuracy of determining phase resonance under the two different operating conditions.

[0085] The phase resonance risk identification method of the present application has guiding significance for the frequency error design in the rotor and plant design stages of new power plants, as well as the cause analysis and treatment of abnormal vibration and noise in power plants that have been put into operation.

[0086] A specific implementation process of the method for identifying the risk of phase resonance of a pump-turbine described in this application is provided below.

[0087] The speed of a pumped storage power station unit is 500r / min, and the number of movable guide vanes is Z. g The number of runner blades is 16. r is 5+5 (5 long and 5 short), the diameter of the circumscribed circle of the fixed guide vane of the unit is D SV The diameter of the volute inlet section is 7232.8 mm. SC It is 2098mm.

[0088] S1: Carry out pressure pulsation test on the unit to determine the dominant frequencies of each order of excitation source.

[0089] Differential pressure sensors are arranged at the volute inlet, between the impeller and the movable guide vane in the +X and +Y directions, and between the top cover and the impeller in the +X and +Y directions. The collected pressure pulsation signal (current value) is connected to the data acquisition system, and the signal is Fourier transformed to obtain a spectrum diagram. After analysis, it can be known that the main dominant frequencies of the pressure pulsation between the impeller and the movable guide vane and the volute inlet are: 10f n , 15f n , 5f n and 20f n .

[0090] S2: Calculate the pressure wave wavelength corresponding to each order of dominant frequency according to the operating conditions of the pump turbine.

[0091] Unit frequency f n =500 / 60=8.33Hz. In order to consider the risk of phase resonance caused by several harmonics, 25f is also calculated here. n and 30f n Phase resonance risk factor of harmonics.

[0092] The following calculations are based on the case where the impeller rotates counterclockwise, i.e., the pump operating condition. Figure 2 According to the excitation law shown in Table 1, when the runner rotates counterclockwise, the excitation interval Δg of the guide vane combination of 5+5+16 blades is a =5, because for a 10-blade impeller, the blade spacing angle is 36°, and the 16 guide vanes are placed at an angle of 22.5°. Assuming that at time 0, the distance between blade 1 and guide vane 1 is the smallest, generating one excitation, then after the impeller rotates counterclockwise for a period of time, the distance between blade 4 and guide vane 6 is the smallest, generating the second excitation, so the guide vane excitation interval Δg a 6-1=5.5f n , 10f n , 15f n , 20f n , 25f n and 30fn The corresponding harmonic frequencies are: 41.67Hz, 83.33Hz, 125Hz, 166.67Hz, 208.33Hz and 250Hz. a Usually 1200m / s is taken, then according to the formula λ k =a a / f k , the wavelengths corresponding to each frequency order can be calculated as shown in Table 2.

[0093] Table 2 Pressure wave wavelength corresponding to each order of dominant frequency

[0094] Frequency (Hz) <![CDATA[5f n ]]> <![CDATA[10f n ]]> <![CDATA[15f n ]]> <![CDATA[20f n ]]> <![CDATA[25f n ]]> <![CDATA[30f n ]]> Wavelength(m) 28.80000 14.40058 9.60000 7.2 5.76009 4.80000

[0095] S3: Calculate the position difference between the two pressure waves transmitted when two adjacent excitations occur according to the pump-turbine operating conditions.

[0096] The position difference ΔS between the two pressure waves transmitted when two adjacent excitations occur is:

[0097]

[0098] Where the guide vane excitation interval Δg a =5, the equivalent diameter of the volute is D sp =D SV +D SC =8.2818m, we can get ΔS a =6.329919m.

[0099] S4: Substitute the wavelength of the pressure wave corresponding to each order of dominant frequency and the position difference under different pump-turbine operating conditions into the phase resonance risk coefficient calculation formula to calculate the phase resonance risk coefficient of the pressure wave corresponding to each order of dominant frequency.

[0100] When the position difference ΔS is an integer multiple of a certain order wavelength, the peaks and troughs of the harmonics excited at each measuring point are close to superposition, and the pressure pulsation amplitude of the volute is amplified by a large factor, resulting in phase resonance. According to the optimized phase resonance risk coefficient calculation formula (13), the phase resonance risk coefficients of the pressure waves corresponding to each order frequency are calculated and shown in Table 3 below.

[0101] Table 3 Phase resonance risk coefficient calculated for pump operating conditions

[0102]

[0103] The harmonics corresponding to the phase oscillation (short for phase resonance) risk coefficient less than 0.2 in Table 3 are the harmonic orders that may produce phase resonance.

[0104] Similarly, when the runner rotates clockwise, that is, when the turbine is operating, the calculation results of the phase resonance risk coefficient are shown in Table 4 below.

[0105] Table 4 Phase resonance risk coefficient calculated for turbine operating conditions

[0106]

[0107] S5: Compare the phase resonance risk coefficient of the pressure wave corresponding to each order of dominant frequency with the risk determination coefficient to identify the harmonic order with phase resonance risk.

[0108] From the calculation results in Table 3, it can be seen that under the pump working condition, 20f n and 25f n Frequency pressure pulsation may produce phase resonance. From the calculation results in Table 4, it can be seen that under the turbine operating condition, 5f n , 25f n and 30f n Frequency pressure pulsation may produce phase resonance. It is necessary to focus on these frequency component pressure pulsations.

[0109] S6: For newly designed power plants, since pressure pulsations will be transmitted upstream to the powerhouse, staggered frequency design should be considered for the above-mentioned frequency components that may cause phase resonance during the runner design and powerhouse design.

[0110] For power stations that have been put into operation, synchronous on-site tests including the plant can be carried out. Acceleration sensors and differential pressure sensors are arranged in the +X and +Y directions between the top cover and the runner, in the +X and +Y and -X and -Y directions of the volute inlet, and in the volute layer of the plant, the turbine layer, the busbar layer and the generator layer. When processing data, focus on the vibration acceleration values ​​and frequency amplitudes of several frequency components that may produce phase resonance in the S4 calculation results, analyze the causes of their occurrence, and propose targeted treatment measures.

[0111] This application analyzes the multi-component frequency pressure waves between the runner and the movable guide vanes from the aspects of the excitation mechanism, excitation sequence, blade combination and experimental test of the dynamic-static interference pressure waves under turbine operating conditions and water pump operating conditions, which has important guiding significance for the design of new power plants and the analysis of the causes of abnormal vibrations in power plants that have been put into operation.

[0112] The method of the present application can determine which order of pressure pulsation is more likely to produce phase resonance. The order of the pressure wave is directly related to the number of runner blades and guide vanes. By changing the combination of the guide vanes and the runner blades, or changing the volute inlet cross-sectional diameter and / or changing the guide vane circumscribed circle diameter (to change the volute equivalent diameter D sp ), the pressure pulsation order k that may produce phase resonance can be changed. The purpose of frequency deviation can also be achieved by changing the natural frequency of the plant, thereby effectively reducing the level of abnormal vibration and noise in the plant.

[0113] In an exemplary embodiment, the present application also provides a computer device, which may be a server or a terminal. The computer device includes a processor, a memory, an input / output interface, and a communication interface. The processor, the memory, and the input / output interface are connected via a system bus, and the communication interface is connected to the system bus via the input / output interface. The processor of the computer device is used to provide computing and control capabilities. The memory of the computer device includes a non-volatile storage medium and an internal memory. The non-volatile storage medium stores an operating system, a computer program, and a database. The internal memory provides an environment for the operation of the operating system and the computer program in the non-volatile storage medium. The input / output interface of the computer device is used to exchange information between the processor and an external device. The communication interface of the computer device is used to communicate with an external terminal via a network connection. When the computer program is executed by the processor, the pump-turbine phase resonance risk identification method is implemented.

[0114] In an exemplary embodiment, the present application also provides a computer-readable storage medium having a computer program stored thereon, and when the computer program is executed by a processor, the method for identifying the risk of phase resonance of a pump-turbine is implemented.

[0115] In an exemplary embodiment, the present application also provides a computer program product, including a computer program, which implements the pump-turbine phase resonance risk identification method when executed by a processor.

[0116] It can be understood by a person of ordinary skill in the art that all or part of the processes in the above-mentioned embodiment method can be completed by hardware related to computer program instructions, and the computer program can be stored in a non-volatile computer-readable storage medium, and the computer program can include the process of the embodiment of the above-mentioned method when executed. Among them, any reference to memory or other media in each embodiment provided in the present application can include at least one of non-volatile and volatile memory. Non-volatile memory can include read-only memory (ROM), magnetic tape, floppy disk, flash memory, optical memory, high-density embedded non-volatile memory, resistive random access memory (ReRAM), magnetic random access memory (MRAM), ferroelectric random access memory (FRAM), phase change memory (PCM), graphene memory, etc. Volatile memory can include random access memory (RAM) or external cache memory, etc. By way of illustration and not limitation, RAM may be in various forms, such as static random access memory (SRAM) or dynamic random access memory (DRAM).

[0117] It should be noted that the information (including but not limited to user device information, user personal information, etc.) and data (including but not limited to data used for analysis, stored data, displayed data, etc.) involved in this application are all information and data authorized by the user or fully authorized by all parties, and the collection, use and processing of relevant data must comply with relevant regulations.

[0118] The technical features of the above embodiments may be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0119] This article uses specific examples to illustrate the principles and implementation methods of this application. The description of the above embodiments is only used to help understand the method and core ideas of this application. At the same time, for those skilled in the art, according to the ideas of this application, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as limiting this application.

Claims

1. A method for identifying phase resonance risk of a pump-turbine, characterized in that: include: Carry out pressure pulsation test on hydro-generator set to determine the dominant frequencies of each order of excitation source; Calculate the pressure wave wavelength corresponding to each order of dominant frequency according to the pump turbine operating conditions; According to the pump-turbine operating conditions, the position difference between the two pressure waves transmitted when two adjacent excitations occur is calculated; Substitute the pressure wave wavelength corresponding to each order of dominant frequency and the position difference under different pump-turbine operating conditions into the phase resonance risk coefficient calculation formula to calculate the phase resonance risk coefficient of the pressure wave corresponding to each order of dominant frequency; The phase resonance risk coefficient of the pressure wave corresponding to each order of dominant frequency is compared with the risk determination coefficient to identify the harmonic order with phase resonance risk.

2. The method for identifying the risk of phase resonance of a pump-turbine according to claim 1, characterized in that: The pressure pulsation test on the hydro-generator set is carried out to determine the dominant frequencies of each order of the excitation source, specifically including: Differential pressure sensors are arranged at the measuring points of the volute inlet of the hydro-turbine generator set, the +X and +Y directions between the impeller and the movable guide vane, and the +X and +Y directions between the top cover and the impeller, and the collected pressure pulsation signals are connected to the data acquisition system, and the signals are Fourier transformed to obtain the spectrum diagram; The frequency spectra at different measuring points are analyzed to obtain the main dominant frequencies of the pressure pulsation between the runner and the movable guide vane and at the volute inlet, which are used as the dominant frequencies of each order of the excitation source.

3. The method for identifying the risk of phase resonance of a pump-turbine according to claim 2, characterized in that: The step of calculating the pressure wave wavelength corresponding to each order of dominant frequency according to the working condition of the water pump turbine specifically includes: When the pump turbine is in pumping condition, the formula λ k =a a / f k Calculate the dominant frequency f of each order k The corresponding pressure wave wavelength λ k ; where a a is the pressure wave transmission speed in counterclockwise condition; f k = k·f n ;f n is the unit rotation frequency; k is the harmonic order; When the pump turbine is in turbine operation, the formula λ k =a c / f k Calculate the dominant frequency f of each order k The corresponding pressure wave wavelength λ k ; where a c is the pressure wave transmission speed in clockwise condition.

4. The method for identifying phase resonance risk of a pump-turbine according to claim 3, characterized in that: The calculating, according to the pump turbine operating condition, the position difference between the two pressure waves transmitted when two adjacent excitations occur specifically includes: When the pump turbine is in pumping condition, the formula is used. Calculate the transmission position difference ΔS of adjacent excitation pressure waves in counterclockwise condition a , as the position difference ΔS between the two pressure waves when two adjacent excitations occur; where Δg a is the number of guide vane excitation intervals when rotating counterclockwise; Z g is the number of active guide vanes; D sp is the equivalent diameter of the volute; Z r is the number of runner blades; (Z r , Z g ) is Z r and Z g The greatest common divisor of; When the pump turbine is in turbine operation, the formula Calculate the transmission position difference ΔS of adjacent excitation pressure waves in clockwise condition c , as the position difference ΔS between the two pressure waves when two adjacent excitations occur; where Δg c It is the number of guide vane excitation intervals when rotating clockwise.

5. The method for identifying the risk of phase resonance of a pump-turbine according to claim 4, characterized in that: Substituting the pressure wave wavelength corresponding to each order of dominant frequency and the position difference under different pump-turbine working conditions into the phase resonance risk coefficient calculation formula, the phase resonance risk coefficient of the pressure wave corresponding to each order of dominant frequency is calculated, specifically including: The dominant frequencies f k The corresponding pressure wave wavelength λ k Substitute the position difference ΔS under different pump-turbine operating conditions into the phase resonance risk coefficient calculation formula Calculate the phase resonance risk coefficient RF of the pressure wave corresponding to each order dominant frequency fk k ; where [] is the rounding symbol.

6. The method for identifying the risk of phase resonance of a pump-turbine according to claim 5, characterized in that: The step of comparing the phase resonance risk coefficient of the pressure wave corresponding to each order of dominant frequency with the risk determination coefficient to identify the harmonic order with phase resonance risk specifically includes: The phase resonance risk coefficient RF of the pressure wave corresponding to each order dominant frequency fk k Compared with the risk determination coefficient σ; when RF k <σ, the corresponding harmonic order k is determined to be the harmonic order k' with a phase resonance risk.

7. The method for identifying the risk of phase resonance of a pump-turbine according to claim 6, characterized in that: Also includes: According to the harmonic order k' with the risk of phase resonance, the frequency component f is k′ Perform frequency staggered design.

8. A computer device comprising: A memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the computer program to implement the pump-turbine phase resonance risk identification method according to any one of claims 1 to 7.

9. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the method for identifying the risk of phase resonance of a pump-turbine according to any one of claims 1 to 7 is implemented.

10. A computer program product, comprising a computer program, characterized in that When the computer program is executed by a processor, the method for identifying the risk of phase resonance of a pump-turbine according to any one of claims 1 to 7 is implemented.

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