A method and device for identifying rotational stall of a pump turbine

Abstract

The present invention relates to the technical field of water turbines, and discloses a method and device for identifying rotational stall of a water pump turbine, the method comprising: obtaining basic information and working state of the water pump turbine; based on the basic information, obtaining a first head difference, a second head difference and a third head difference, wherein the first head difference is the head difference of the water pump turbine inlet section, the second head difference is the head difference of the water pump turbine runner section, and the third head difference is the head difference of the water pump turbine outlet section; based on the first head difference, the second head difference and the third head difference, determining the overall head difference of the water pump turbine; based on the overall head difference, determining the critical point of the flow field disturbance stable state of the water pump turbine; based on the working state and the critical point of the flow field disturbance stable state, determining whether the water pump turbine is rotationally stalled. The present invention can obtain the starting point of the rotational stall.

Description

Technical Field

[0001] The invention relates to the technical field of water turbines, and in particular to a method and a device for identifying rotational stall of a water pump turbine. Background Art

[0002] The core equipment of a pump-turbine pumped-storage power station is different from a general turbine that is only used for power generation. It needs to have the bidirectional operation capability of the pump and turbine. According to the change of the grid load, it is necessary to frequently switch between power generation and pumping conditions. This complex operating condition and transition process lead to unstable internal flow characteristics.

[0003] In the related art, non-steady numerical calculation methods or model test methods are mainly used to determine in which operating range of the pump-turbine the rotational stall phenomenon exists, but the starting point of the rotational stall cannot be identified and determined.

[0004] In view of this, a rotating stall identification method for a pump turbine is needed that can obtain the rotating stall starting point. Summary of the invention

[0005] In view of this, the present invention provides a method for identifying rotational stall of a pump-turbine, which can obtain the rotational stall starting point of the pump-turbine to improve the stability of the operation of the pump-turbine.

[0006] In a first aspect, the present invention provides a method for identifying rotational stall of a pump-turbine, the method comprising: obtaining basic information and an operating state of the pump-turbine, wherein the basic information comprises fluid density in the pump-turbine and structural information of the pump-turbine; based on the basic information, obtaining a first head difference, a second head difference and a third head difference, wherein the first head difference is the head difference at an inlet section of the pump-turbine, the second head difference is the head difference at a runner section of the pump-turbine, and the third head difference is the head difference at an outlet section of the pump-turbine; based on the first head difference, the second head difference and the third head difference, determining an overall head difference of the pump-turbine; based on the overall head difference, determining a critical point of a stable state of a flow field disturbance of the pump-turbine; and based on the operating state and the critical point of a stable state of a flow field disturbance, determining whether the pump-turbine is rotationally stalled.

[0007] In the embodiment of the present disclosure, by acquiring basic information of the pump-turbine, determining the head difference of the pump-turbine, and determining the critical point of the stable state of the flow field disturbance that is a precursor to the rotational stall of the pump-turbine based on the head difference, the accuracy of identifying the critical point of the stable state of the flow field disturbance that is a precursor to the rotational stall can be improved, and the occurrence of the rotational stall can be predicted.

[0008] In an optional embodiment, based on the basic information, obtaining the first head difference includes: based on the basic information, determining the inlet section pressure information of the pump turbine, wherein the inlet section pressure information includes the inlet section inlet pressure, the undisturbed inlet section outlet pressure and the disturbed inlet section outlet pressure; based on the inlet section pressure information, determining the first head difference.

[0009] In the embodiment of the present disclosure, by obtaining the pressure information of the inlet section of the pump-turbine and determining the first head difference, the head difference of the inlet section of the pump-turbine can be accurately obtained to improve the accuracy of determining the critical point of the stable state of the flow field disturbance that serves as a precursor to the rotating stall.

[0010] In an optional embodiment, obtaining the second head difference includes: determining the degree of hysteresis of the pump-turbine based on basic information; determining a first pressure difference and a second pressure difference of the runner section of the pump-turbine based on the hysteresis degree, wherein the first pressure difference is the inlet and outlet pressure difference of the runner section of the pump-turbine with no disturbance, and the second pressure difference is the inlet and outlet pressure difference of the runner section of the pump-turbine with disturbance; determining the second head difference based on the first pressure difference and the second pressure difference.

[0011] In the disclosed embodiment, the first pressure difference and the second pressure difference of the runner section of the pump-turbine are determined according to the degree of hysteresis of the pump-turbine, and then the second head difference is determined, which can improve the accuracy of the second head difference and improve the identification accuracy of the critical point of the stable state of the flow field disturbance which is the precursor of the rotational stall.

[0012] In an optional embodiment, determining the second head difference based on the first pressure difference and the second pressure difference includes: determining a first runner section head expression based on basic information and the first pressure difference, wherein the first runner section head expression is a steady-state characteristic expression of the pump-turbine runner; determining a second runner section head expression based on the basic information and the second pressure difference, wherein the second runner section head expression is a steady-state characteristic expression and a hysteresis characteristic expression of the pump-turbine runner; determining the second head difference based on the first runner section head expression and the second runner section head expression.

[0013] In the embodiment of the present disclosure, the first runner section water head expression and the second runner section water head expression are determined through the basic information, the first pressure difference and the second pressure difference, and then the second water head difference is determined. The steady-state characteristics and hysteresis characteristics of the pump turbine are comprehensively considered to improve the accuracy of the second water head difference.

[0014] In an optional implementation, the hysteresis characteristic expression is the product of the hysteresis characteristic function and the radial velocity change rate.

[0015] In the embodiment of the present disclosure, the product of the hysteresis characteristic and the radial velocity change rate is used as the hysteresis characteristic expression to improve the robustness of the method.

[0016] In an optional embodiment, obtaining the third head difference includes: constructing a flow equation of the outlet section of the pump-turbine based on basic information; determining a first outlet section head expression and a second outlet section head expression based on the flow equation; determining the third head difference based on the first outlet section head expression and the second outlet section head expression.

[0017] In the embodiment of the present disclosure, the flow equation is constructed to determine the hydraulic head expression of the outlet section, thereby obtaining the third hydraulic head difference, which can improve the calculation precision and accuracy of the method.

[0018] In an optional embodiment, based on the overall head difference, determining the critical point of the flow field disturbance stable state of the pump-turbine includes: performing complex decomposition on the overall head difference to obtain the real part of the overall head difference and the imaginary part of the difference; based on the real part of the difference and the imaginary part of the difference, obtaining the critical point of the flow field disturbance stable state of the pump-turbine.

[0019] In the embodiment of the present disclosure, the overall head difference is divided into a real part and an imaginary part for processing, and a critical point of a flow field disturbance stable state as a precursor of a rotating stall is obtained, which can improve the efficiency of the method.

[0020] In a second aspect, the present invention provides a rotational stall identification device for a pump-turbine, the device comprising: an information acquisition module, used to acquire basic information and working status of the pump-turbine, wherein the basic information includes fluid density in the pump-turbine and pump-turbine structural information; a segmented head difference acquisition module, used to acquire a first head difference, a second head difference and a third head difference based on the basic information, wherein the first head difference is the head difference of an inlet section of the pump-turbine, the second head difference is the head difference of a runner section of the pump-turbine, and the third head difference is the head difference of an outlet section of the pump-turbine; an overall head difference acquisition module, used to determine the overall head difference of the pump-turbine based on the first head difference, the second head difference and the third head difference; a critical point determination module, used to determine the critical point of a flow field disturbance stable state of the pump-turbine based on the overall head difference; and a rotational stall determination module, used to determine whether the pump-turbine is rotationally stalled based on the working status and the critical point of a flow field disturbance stable state.

[0021] In a third aspect, the present invention provides a computer device, comprising: a memory and a processor, the memory and the processor being communicatively connected to each other, the memory storing computer instructions, and the processor executing the method for identifying rotational stall of a pump turbine according to the first aspect or any corresponding embodiment thereof by executing the computer instructions.

[0022] In a fourth aspect, the present invention provides a computer-readable storage medium having computer instructions stored thereon, the computer instructions being used to enable a computer to execute the method for identifying rotational stall of a pump-turbine according to the first aspect or any corresponding embodiment thereof. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0024] Figure 1 is a schematic flow chart of a method for identifying a rotating stall of a pump turbine according to an embodiment of the present invention;

[0025] Figure 2 is a flow chart of another method for identifying rotating stall of a pump-turbine according to an embodiment of the present invention;

[0026] Figure 3 is a flow chart of another method for identifying rotating stall of a pump-turbine according to an embodiment of the present invention;

[0027] Figure 4 is a structural block diagram of a rotating stall identification device for a pump turbine according to an embodiment of the present invention;

[0028] Figure 5 It is a schematic diagram of the hardware structure of a computer device according to an embodiment of the present invention. DETAILED DESCRIPTION

[0029] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present invention.

[0030] An embodiment of the present invention provides a method for identifying rotational stall of a pump-turbine. By constructing a pump-turbine runner model including an inlet section, a runner section and an outlet section, the head differences of the inlet section, the runner section and the outlet section are obtained respectively, so as to obtain the overall head difference of the pump-turbine, thereby improving the accuracy of obtaining the subsequent rotational stall starting point.

[0031] According to an embodiment of the present invention, an embodiment of a method for identifying rotating stall of a pump turbine is provided. It should be noted that the steps shown in the flowchart of the accompanying drawings can be executed in a computer system such as a set of computer executable instructions, and although a logical order is shown in the flowchart, in some cases, the steps shown or described can be executed in an order different from that shown here.

[0032] In this embodiment, a method for identifying rotational stall of a pump turbine is provided. Figure 1 FIG. 4 is a flow chart of a method for identifying a rotating stall of a pump turbine according to an embodiment of the present invention. Figure 1 As shown, the process includes the following steps:

[0033] Step S101, obtaining basic information and working status of the pump-turbine, wherein the basic information includes fluid density in the pump-turbine and structural information of the pump-turbine.

[0034] The fluid density in the pump turbine can be directly measured by a density meter, and the structural information can be obtained from the design manual of the pump turbine. The working state of the pump turbine can be obtained in any way. It can be monitored in real time by a relevant state monitoring system, or by installing a sensor in the pump turbine and analyzing the data collected by the sensor to obtain the working state of the pump turbine. The choice of sensor is not limited, and temperature sensors, pressure sensors, flow sensors, etc. can be selected according to actual conditions.

[0035] Step S102, based on the basic information, obtain the first head difference, the second head difference and the third head difference, wherein the first head difference is the head difference at the inlet section of the pump-turbine, the second head difference is the head difference at the runner section of the pump-turbine, and the third head difference is the head difference at the outlet section of the pump-turbine.

[0036] Among them, the method of obtaining the first head difference, the second head difference and the third head difference is not restricted. The internal flow of the pump turbine can be simulated through relevant software, and then the head difference of the turbine can be obtained in sections, where the simulation includes weak disturbance flow simulation and undisturbed flow simulation. It is also possible to construct a theoretical simplified model of the turbine, assuming that the flow field without rotating stall is circumferentially uniform and smooth with several blades, and the weak disturbance is expressed in the form of waves. By analyzing the theoretical simplified model, the head difference of the inlet section, runner section and outlet section can be obtained.

[0037] Step S103, determining the overall water head difference of the pump turbine based on the first water head difference, the second water head difference and the third water head difference.

[0038] The sum of the first head difference, the second head difference and the third head difference can be directly used as the overall head difference of the pump turbine. After obtaining the overall head difference, the overall head difference can also be adjusted considering the situation that friction, local resistance, etc. may affect the head change.

[0039] Step S104, determining the critical point of the flow field disturbance stable state of the pump-turbine based on the overall water head difference.

[0040] Among them, the overall head difference is the head difference between the presence of a weak disturbance and the absence of a disturbance inside the turbine. When the overall head difference of the turbine is zero, the weak disturbance inside the turbine is the weak disturbance that can develop into a rotating stall, and the operating point of the turbine is the critical point of the rotating stall. Therefore, by setting the overall head difference to zero, the relationship between the critical point of the stable state of the flow field disturbance, which is the predecessor of the rotating stall, can be obtained.

[0041] Step S105, determining whether the pump turbine is in rotational stall based on the working state and the critical point of the flow field disturbance stable state.

[0042] Among them, the operating point of the turbine is determined according to the working state of the turbine. If the operating point of the turbine is a critical point of the flow field disturbance stable state that is a precursor of the rotating stall, it can be determined that the pump turbine has a rotating stall phenomenon.

[0043] The method for identifying rotational stall of a pump-turbine provided in this embodiment obtains basic information of the pump-turbine, determines the head difference of the pump-turbine, and determines the critical point of the stable state of the flow field disturbance of the pump-turbine as a precursor to the rotational stall based on the head difference. This can improve the accuracy of identifying the critical point of the stable state of the flow field disturbance as a precursor to the rotational stall and prevent the occurrence of rotational stall.

[0044] In this embodiment, a method for identifying rotational stall of a pump turbine is provided. Figure 2 FIG. 4 is a flow chart of a method for identifying a rotating stall of a pump turbine according to an embodiment of the present invention. Figure 2 As shown, the process includes the following steps:

[0045] Step S201, obtaining basic information and working status of the pump-turbine, wherein the basic information includes fluid density in the pump-turbine and structural information of the pump-turbine.

[0046] For details, please see Figure 1 Step S101 of the illustrated embodiment will not be described in detail here.

[0047] Step S202, based on the basic information, obtain the first head difference, the second head difference and the third head difference, wherein the first head difference is the head difference at the inlet section of the pump-turbine, the second head difference is the head difference at the runner section of the pump-turbine, and the third head difference is the head difference at the outlet section of the pump-turbine.

[0048] Specifically, the above step S202 includes:

[0049] Step S2021, obtaining a first water head difference based on basic information.

[0050] The method for obtaining the first water head difference is not limited. In the actual operation of the pump turbine, a corresponding sensor can be installed to detect the water head. Then, the sensor data under normal working conditions without disturbance and under disturbance test are recorded respectively. By comparing the water head data under the conditions of no disturbance and disturbance, and obtaining the difference between the two, the first water head difference can be obtained.

[0051] In some optional implementations, the above step S2021 includes:

[0052] Step a1, based on the basic information, determine the inlet section pressure information of the pump turbine, wherein the inlet section pressure information includes the inlet section inlet pressure, the undisturbed inlet section outlet pressure and the disturbed inlet section outlet pressure.

[0053] There is no restriction on the method of obtaining the inlet section pressure information, and a pressure sensor can be placed inside the pump turbine to obtain the inlet section pressure information. The location of the pressure sensor is not restricted and can be selected according to the actual situation and the internal structure of the pump turbine.

[0054] The outlet pressure of the pump-turbine with a disturbed inlet section can be measured by introducing a disturbance factor.

[0055] Step a2: determining a first water head difference based on the inlet section pressure information.

[0056] The water heads of the pump-turbine inlet section with and without disturbance can be obtained respectively first, and then the water head difference between the water head with and without disturbance is used as the first water head difference.

[0057] In a practical application, the expression of the head change in the inlet section of a pump-turbine with disturbance is as follows:

[0058]

[0059] in, is the head change at the inlet section of the pump-turbine with disturbance, is the inlet pressure of the inlet section, is the outlet pressure of the disturbed inlet section, is the density of the fluid, g is the acceleration due to gravity.

[0060] The expression of the head change at the inlet section of the pump turbine without disturbance is as follows:

[0061]

[0062] in, is the head change at the undisturbed inlet section of the pump-turbine, is the inlet pressure of the inlet section, is the outlet pressure of the undisturbed inlet section, is the density of the fluid, g is the acceleration due to gravity.

[0063] The difference between the expression of the head change of the inlet section with disturbance and the expression of the head change of the inlet section without disturbance is taken as the first head difference, where the first head difference is shown as follows:

[0064]

[0065] in, and is the first head difference, is the outlet pressure of the disturbed inlet section, is the outlet pressure of the undisturbed inlet section, is the density of the fluid, g is the acceleration due to gravity.

[0066] By obtaining the pressure information of the inlet section of the pump-turbine and determining the first head difference, the head difference of the inlet section of the pump-turbine can be accurately obtained to improve the accuracy of determining the critical point of the subsequent flow field disturbance stable state as a precursor of rotating stall.

[0067] Step S2022: obtaining a second water head difference based on the basic information.

[0068] The method for obtaining the second water head difference is not limited, and a corresponding sensor can be installed to detect the water head during the actual operation of the pump turbine. Then, the sensor data in the undisturbed state and the disturbed state are recorded for analysis, and the water heads of the runner section of the pump turbine in the undisturbed state and the disturbed state are obtained, and the difference between the water heads in the disturbed state and the undisturbed state is used as the second water head difference.

[0069] In some optional implementations, the above step S2022 includes:

[0070] Step b1, based on the basic information, determining the hysteresis degree of the pump turbine.

[0071] There is no restriction on the method of obtaining the hysteresis degree of the pump turbine, and the hysteresis degree can be obtained by simulation through relevant software.

[0072] Step b2, based on the degree of hysteresis, determine the first pressure difference and the second pressure difference of the runner section of the pump-turbine, wherein the first pressure difference is the inlet and outlet pressure difference of the runner section of the pump-turbine without disturbance, and the second pressure difference is the inlet and outlet pressure difference of the runner section of the pump-turbine with disturbance.

[0073] The first pressure difference and the second pressure difference of the pump turbine runner can be obtained by the pressure sensor, and then the pressure change curve of the pump turbine runner can be obtained according to the hysteresis degree. According to the pressure change curve, the pressure change caused by the hysteresis phenomenon in the first pressure difference and the second pressure difference can be removed.

[0074] Step b3, determining a second water head difference based on the first pressure difference and the second pressure difference.

[0075] The first pressure difference and the second pressure difference can be substituted into the water head expression respectively to obtain the water head expression of the turbine under undisturbed and disturbed conditions, and the difference between the two water head expressions is taken as the second water head difference.

[0076] According to the hysteresis degree of the pump-turbine, the first pressure difference and the second pressure difference of the runner section of the pump-turbine are determined, and then the second head difference is determined, which can improve the accuracy of the second head difference and improve the recognition accuracy of the critical point of the stable state of the flow field disturbance as a precursor of the rotating stall.

[0077] In some optional implementations, the above step b3 includes:

[0078] Step b31, based on the basic information and the first pressure difference, determine the first runner section water head expression, wherein the first runner section water head expression is the steady-state characteristic expression of the pump turbine runner.

[0079] The first pressure difference can be directly substituted into the water head calculation formula to determine the water head expression of the first runner section. The water head expression of the first runner section is the water head expression of the runner section in the absence of disturbance, so it can be expressed as the steady-state characteristic expression of the pump turbine runner.

[0080] Step b32, based on the basic information and the second pressure difference, determine the second runner section water head expression, wherein the second runner section water head expression is the steady-state characteristic expression and the hysteresis characteristic expression of the pump turbine runner.

[0081] Among them, the second pressure difference can be directly substituted into the water head calculation formula to determine the water head expression of the second runner section. The water head expression of the second runner section is the water head expression of the runner section in the presence of weak disturbances, which is not only related to the steady-state characteristics of the runner, but also to the hysteresis phenomenon in the runner, and can be expressed as the sum of the steady-state characteristic expression and the hysteresis characteristic expression of the pump-turbine runner.

[0082] Step b33, determining the second water head difference based on the first runner section water head expression and the second runner section water head expression.

[0083] Among them, the difference between the water head expression of the second impeller section and the water head expression of the first impeller section can be directly used as the second water head difference.

[0084] In a practical application, the water head expression of the first runner section is as follows:

[0085]

[0086] in, is the water head of the first runner section, is the runner inlet pressure without disturbance, is the runner outlet pressure without disturbance, is the density of the fluid, g is the acceleration due to gravity, is the steady-state characteristic expression.

[0087] The water head expression of the second runner section is as follows:

[0088]

[0089] in, is the water head of the second runner section, is the runner inlet pressure under disturbance, is the outlet pressure of the runner section under disturbance, is the density of the fluid, g is the acceleration due to gravity, is the steady-state characteristic expression, is the flow rate in the runner and the pump turbine The associated hysteresis function, is the sum of the average radial velocity coefficient and the radial velocity coefficient disturbance, for The rate of change is shown below:

[0090]

[0091] in, is the rate of change of the axial rotation of the flow disturbance, is the angular rate of change of axial rotation, is the angular velocity, which can be obtained by the following formula:

[0092]

[0093] in, U is the high-pressure side speed of the runner, D is the diameter of the wheel, f is the wheel rotation frequency.

[0094] Therefore, the second head difference is as follows:

[0095]

[0096] in, is the second head difference.

[0097] The first runner section water head expression and the second runner section water head expression are determined through the basic information, the first pressure difference and the second pressure difference, and then the second water head difference is determined. The steady-state characteristics and hysteresis characteristics of the pump turbine are comprehensively considered to improve the accuracy of the second water head difference.

[0098] In some optional embodiments, the hysteresis characteristic expression is the product of the hysteresis characteristic function and the radial velocity change rate.

[0099] The product of hysteresis characteristic and radial velocity change rate is used as the hysteresis characteristic expression to improve the robustness of the method.

[0100] Step S2023: obtaining a third water head difference based on the basic information.

[0101] There is no restriction on the method of obtaining the third water head difference. The pressure difference of the outlet section under different conditions can be obtained by installing a sensor, and the third water head difference can be obtained according to the pressure difference.

[0102] In some optional implementations, the above step S2023 includes:

[0103] Step c1, constructing the flow equation of the outlet section of the pump turbine based on the basic information.

[0104] There is no restriction on the way of constructing the flow equation, and relevant platforms or software can be used to select a suitable model to construct the flow equation.

[0105] Step c2, based on the flow equation, determine the first outlet section water head expression and the second outlet section water head expression.

[0106] The hydraulic head expression of the first outlet section is the hydraulic head expression under undisturbed conditions, and the hydraulic head expression of the second outlet section is the hydraulic head expression under weak disturbance conditions. The flow equation can be used to obtain the change in water energy under undisturbed conditions and under weak disturbance conditions, and the hydraulic head expressions under the two conditions can be obtained based on the change in water energy.

[0107] Step c3, determining a third water head difference based on the first outlet section water head expression and the second outlet section water head expression.

[0108] Among them, the difference between the water head expression of the second outlet section and the water head expression of the first outlet section can be directly used as the third water head difference.

[0109] In a practical application, the flow at the outlet of a pump turbine satisfies axisymmetric flow, and the flow in this section is characterized by the stream function and the head coefficient, as shown in the following formula:

[0110]

[0111] Among them, u is the flow velocity of the liquid in the outlet section of the turbine in the x direction, v is the flow velocity of the liquid in the outlet section of the turbine in the x direction, U is the high-pressure side velocity of the runner, is the stream function of the liquid in the outlet section in the y direction, is the stream function of the liquid in the x direction at the outlet, is the pressure at the outlet of the outlet section, is the pressure at the outlet of the outlet section, is the water head at the outlet section.

[0112] Then the NS (Navier-Stokes) equation of the outlet section of the water turbine is obtained, and the NS equation of the outlet section of the pump turbine is simplified, where the equation simplification includes ignoring second-order infinitesimals, etc. After the simplification, the first outlet condition of the pump turbine is entered, and the liquid flow expression with and without disturbance at the outlet section of the pump turbine can be obtained. In a practical application, the outlet condition is that the pressure disturbance in the pump turbine is zero.

[0113] The expression of liquid flow with disturbance in the outlet section is as follows:

[0114]

[0115] in, is the stream function of the liquid in the outlet section in the y direction when there is a disturbance in the outlet section, is the stream function of the outlet head in the y direction when there is a disturbance in the outlet section, is the wheel rotation frequency, is the average radial velocity coefficient of the pump-turbine runner, is the axial velocity disturbance at the inlet of the pump-turbine outlet section, is the axial velocity coefficient, is the circumferential velocity disturbance at the inlet of the pump-turbine outlet section, is the head change at the outlet section.

[0116] The expression of undisturbed liquid flow at the outlet section is as follows:

[0117]

[0118] in, is the stream function of the liquid in the outlet section in the y direction when there is no disturbance in the outlet section, is the stream function of the outlet head in the y direction when the outlet is disturbed, is the average radial velocity coefficient of the pump-turbine runner, is the axial velocity coefficient, is the head change at the outlet section.

[0119] The difference between the liquid flow expression with disturbance and the liquid flow expression without disturbance in the outlet section is obtained to obtain the third head difference, where the third head difference is shown in the following formula:

[0120]

[0121] in, is the third head difference, is the wheel rotation frequency, is the average circumferential velocity coefficient of the pump-turbine runner, is the axial velocity disturbance at the inlet of the pump-turbine outlet section.

[0122] By constructing the flow equation, the head expression of the outlet section is determined, and then the third head difference is obtained, which can improve the calculation precision and accuracy of the method.

[0123] Step S203: determining the overall water head difference of the pump turbine based on the first water head difference, the second water head difference and the third water head difference.

[0124] For details, please see Figure 1 Step S103 of the illustrated embodiment will not be described in detail here.

[0125] Step S204: determining the critical point of the flow field disturbance stable state of the pump-turbine based on the overall water head difference.

[0126] For details, please see Figure 1 Step S104 of the illustrated embodiment will not be described in detail here.

[0127] Step S205, determining whether the pump turbine is in rotational stall based on the working state and the critical point of the flow field disturbance stable state.

[0128] For details, please see Figure 1 Step S105 of the illustrated embodiment will not be described in detail here.

[0129] The method for identifying rotating stall of a pump-turbine provided in this embodiment analyzes the head difference between the presence and absence of disturbance in the pump-turbine in sections according to the characteristics of the internal structure of the pump-turbine, thereby improving the accuracy of rotating stall identification.

[0130] In this embodiment, a method for identifying rotational stall of a pump turbine is provided. Figure 3 FIG. 4 is a flow chart of a method for identifying a rotating stall of a pump turbine according to an embodiment of the present invention. Figure 3 As shown, the process includes the following steps:

[0131] Step S301, obtaining basic information and working status of the pump-turbine, wherein the basic information includes fluid density in the pump-turbine and structural information of the pump-turbine.

[0132] For details, please see Figure 1 Step S101 of the illustrated embodiment will not be described in detail here.

[0133] Step S302, based on the basic information, obtain the first head difference, the second head difference and the third head difference, wherein the first head difference is the head difference at the inlet section of the pump-turbine, the second head difference is the head difference at the runner section of the pump-turbine, and the third head difference is the head difference at the outlet section of the pump-turbine.

[0134] For details, please see Figure 1 Step S102 of the illustrated embodiment will not be described in detail here.

[0135] Step S303: determining the overall water head difference of the pump turbine based on the first water head difference, the second water head difference and the third water head difference.

[0136] For details, please see Figure 1 Step S103 of the illustrated embodiment will not be described in detail here.

[0137] Step S304: determining the critical point of the flow field disturbance stable state of the pump-turbine based on the overall water head difference.

[0138] Specifically, the above step S304 includes:

[0139] Step S3041, performing complex decomposition on the overall water head difference to obtain the real part and imaginary part of the overall water head difference.

[0140] Among them, the method of complex number decomposition is not restricted. The signal can be decomposed by Fourier transform, or the normal modulus method can be used to separate variables of the overall head difference.

[0141] Step S3042: based on the real part of the difference and the imaginary part of the difference, obtain the critical point of the flow field disturbance stable state of the pump-turbine.

[0142] Among them, by setting the real part of the difference and the imaginary part of the difference to zero, we can obtain a set of equations about the overall head difference, where the set of equations includes equations with zero real part of the difference and equations with zero imaginary part of the difference. The set of equations is the critical condition for the stability of the system in the pump-turbine. The operating point where the set of equations is established is the starting point of the pump-turbine rotational stall.

[0143] In a practical application, the difference in overall head in a pump-turbine runner with and without disturbance is given by:

[0144]

[0145] in, is the overall head difference, is the water wheel difference of the pump turbine inlet section, is the flow rate in the runner and the pump turbine The associated hysteresis function, is the rate of change of radial velocity coefficient disturbance, U is the high-pressure side speed of the runner, D is the diameter of the wheel, f is the wheel rotation frequency, is the average radial velocity coefficient of the pump-turbine runner, is the axial velocity disturbance at the inlet of the pump-turbine outlet section.

[0146] Among them, the axial velocity disturbance at the inlet of the pump-turbine outlet section is expressed as follows:

[0147]

[0148] in, is the rate of change of the axial velocity disturbance at the inlet of the pump-turbine outlet section, is the ratio of the inlet and outlet flow areas of the pump-turbine runner section, is the radial velocity coefficient disturbance.

[0149] Then use the regular modulus method to separate the variables, as shown below:

[0150]

[0151]

[0152] in, is the radial velocity coefficient disturbance, R (1) is the amplitude of the radial velocity coefficient disturbance at the runner inlet. is the exponential property of complex numbers, n is the harmonic order, and 𝜃 is the phase angle. is the head difference with and without disturbance at the pump-turbine inlet, and P(1) is the pressure disturbance at the pump-turbine inlet.

[0153] In the right P(1) After Euler decomposition, we can get the following formula:

[0154]

[0155] in, for The real part of for The imaginary part of .

[0156] Then, substituting the decomposed variables back into the formula of the overall head difference, setting the real and imaginary parts of the overall head difference to zero, the critical condition for the pump-turbine rotating stall can be obtained, as shown in the following formula:

[0157]

[0158] Where n is the period of the pump turbine runner, is the ratio of the inlet and outlet flow areas of the pump-turbine runner section, It is the head change rate of the pump-turbine under undisturbed conditions, wherein the head change of the pump-turbine can be directly obtained by obtaining the ratio of the overall pressure difference to the density of the fluid working medium in the pump-turbine and the acceleration of gravity, and the overall pressure difference is the difference between the pressure at the inlet of the pump-turbine inlet section and the pressure at the outlet of the outlet section.

[0159] Step S305, determining whether the pump turbine is in rotational stall based on the working state and the critical point of the flow field disturbance stable state.

[0160] For details, please see Figure 1 Step S105 of the illustrated embodiment will not be described in detail here.

[0161] The rotating stall identification method of the pump turbine provided in this embodiment divides the overall head difference into real part and imaginary part for processing, and obtains the critical point of the flow field disturbance stable state, which can improve the efficiency of the method.

[0162] In this embodiment, a rotational stall identification device for a pump turbine is also provided, which is used to implement the above-mentioned embodiments and preferred implementation modes, and the descriptions that have been made will not be repeated. As used below, the term "module" can be a combination of software and / or hardware that implements a predetermined function. Although the device described in the following embodiments is preferably implemented in software, the implementation of hardware, or a combination of software and hardware, is also possible and conceivable.

[0163] This embodiment provides a rotational stall identification device for a pump turbine, such as Figure 4 As shown, including:

[0164] The information acquisition module 401 is used to acquire basic information and working status of the pump-turbine, wherein the basic information includes the fluid density in the pump-turbine and the structure information of the pump-turbine.

[0165] The segmented head difference acquisition module 402 is used to obtain the first head difference, the second head difference and the third head difference based on the basic information, wherein the first head difference is the head difference of the pump-turbine inlet section, the second head difference is the head difference of the pump-turbine runner section, and the third head difference is the head difference of the pump-turbine outlet section.

[0166] The overall water head difference acquisition module 403 is used to determine the overall water head difference of the pump-turbine based on the first water head difference, the second water head difference and the third water head difference.

[0167] The critical point determination module 404 is used to determine the critical point of the flow field disturbance stable state of the pump-turbine based on the overall head difference.

[0168] The rotating stall determination module 405 is used to determine whether the pump turbine is rotating stalled based on the working state and the critical point of the flow field disturbance stable state.

[0169] In some optional implementations, the segmented water head difference acquisition module 402 includes:

[0170] The first water head difference obtaining unit is used to obtain the first water head difference.

[0171] The second water head difference obtaining unit is used to obtain the second water head difference.

[0172] The third water head difference obtaining unit is used to obtain the third water head difference.

[0173] In some optional implementations, the first water head difference acquisition unit includes:

[0174] The pressure information determination subunit is used to determine the inlet section pressure information of the pump turbine based on the basic information, wherein the inlet section pressure information includes the inlet section inlet pressure, the undisturbed inlet section outlet pressure and the disturbed inlet section outlet pressure.

[0175] The first water head difference determination subunit is used to determine the first water head difference based on the inlet section pressure information.

[0176] In some optional implementations, the second water head difference acquisition unit includes:

[0177] The hysteresis degree determination subunit is used to determine the hysteresis degree of the pump turbine based on the basic information.

[0178] The impeller section pressure difference determination subunit is used to determine the first pressure difference and the second pressure difference of the impeller section of the pump-turbine based on the degree of hysteresis, wherein the first pressure difference is the inlet and outlet pressure difference of the impeller section of the pump-turbine without disturbance, and the second pressure difference is the inlet and outlet pressure difference of the impeller section of the pump-turbine with disturbance.

[0179] The second water head difference determining subunit is used to determine a second water head difference based on the first pressure difference and the second pressure difference.

[0180] In some optional embodiments, the second water head difference determining subunit includes:

[0181] The first runner section water head expression determination component is used to determine the first runner section water head expression based on basic information and the first pressure difference, wherein the first runner section water head expression is a steady-state characteristic expression of the pump turbine runner.

[0182] The second runner section water head expression determination component is used to determine the second runner section water head expression based on the basic information and the second pressure difference, wherein the second runner section water head expression is the steady-state characteristic expression and the hysteresis characteristic expression of the pump turbine runner.

[0183] The second water head difference determination component is used to determine the second water head difference based on the first runner section water head expression and the second runner section water head expression.

[0184] In some optional embodiments, the hysteresis characteristic expression determined in the second runner section head expression determination component is the product of the hysteresis characteristic function and the radial velocity change rate.

[0185] In some optional embodiments, the third water head difference unit includes:

[0186] The flow equation construction subunit is used to construct the flow equation of the outlet section of the pump-turbine based on the basic information.

[0187] The outlet section water head expression determination subunit is used to determine the first outlet section water head expression and the second outlet section water head expression based on the flow equation.

[0188] The third water head difference determination subunit is used to determine the third water head difference based on the first outlet section water head expression and the second outlet section water head expression.

[0189] In some optional implementations, the critical point determination module 404 includes:

[0190] The decomposition unit is used to perform complex decomposition on the overall water head difference to obtain the real part and imaginary part of the overall water head difference.

[0191] The flow field disturbance stable state critical point acquisition unit is used to acquire the flow field disturbance stable state critical point of the pump turbine based on the real part of the difference and the imaginary part of the difference.

[0192] The further functional description of each of the above modules and units is the same as that of the above corresponding embodiments and will not be repeated here.

[0193] The rotational stall identification device for the pump-turbine in this embodiment is presented in the form of a functional unit, where the unit refers to an ASIC (Application Specific Integrated Circuit) circuit, a processor and memory that executes one or more software or fixed programs, and / or other devices that can provide the above functions.

[0194] The embodiment of the present invention also provides a computer device having the above Figure 4 The rotating stall identification device of the pump turbine is shown.

[0195] See also Figure 5 , Figure 5 is a schematic diagram of the structure of a computer device provided by an optional embodiment of the present invention, such as Figure 5 As shown, the computer device includes: one or more processors 10, a memory 20, and interfaces for connecting various components, including high-speed interfaces and low-speed interfaces. Various components are connected to each other using different buses for communication, and can be installed on a common mainboard or installed in other ways as needed. The processor can process the instructions executed in the computer device, including instructions stored in or on the memory to display the graphical information of the GUI on an external input / output device (such as, a display device coupled to the interface). In some optional embodiments, if necessary, multiple processors and / or multiple buses can be used together with multiple memories and multiple memories. Similarly, multiple computer devices can be connected, and each device provides some necessary operations (for example, as a server array, a group of blade servers, or a multi-processor system). Figure 5 A processor 10 is taken as an example.

[0196] The processor 10 may be a central processing unit, a network processor or a combination thereof. The processor 10 may further include a hardware chip. The hardware chip may be a dedicated integrated circuit, a programmable logic device or a combination thereof. The programmable logic device may be a complex programmable logic device, a field programmable gate array, a general purpose array logic or any combination thereof.

[0197] The memory 20 stores instructions executable by at least one processor 10, so that at least one processor 10 executes the method shown in the above embodiment.

[0198] The memory 20 may include a program storage area and a data storage area, wherein the program storage area may store an operating system, an application required for at least one function; the data storage area may store data created according to the use of the computer device, etc. In addition, the memory 20 may include a high-speed random access memory, and may also include a non-transient memory, such as at least one disk storage device, a flash memory device, or other non-transient solid-state storage device. In some optional embodiments, the memory 20 may optionally include a memory remotely arranged relative to the processor 10, and these remote memories may be connected to the computer device via a network. Examples of the above-mentioned network include, but are not limited to, the Internet, an intranet, a local area network, a mobile communication network, and combinations thereof.

[0199] The memory 20 may include a volatile memory, such as a random access memory; the memory may also include a non-volatile memory, such as a flash memory, a hard disk or a solid state drive; the memory 20 may also include a combination of the above types of memory.

[0200] The computer device also includes an input device 30 and an output device 40. The processor 10, the memory 20, the input device 30 and the output device 40 may be connected via a bus or other means. Figure 5 The example of connecting through bus is taken in the following.

[0201] The input device 30 can receive input digital or character information, and generate key signal input related to the user settings and function control of the computer device, such as a touch screen, a keypad, a mouse, a track pad, a touch pad, an indicator bar, one or more mouse buttons, a trackball, a joystick, etc. The output device 40 may include a display device, an auxiliary lighting device (e.g., an LED) and a tactile feedback device (e.g., a vibration motor), etc. The above-mentioned display device includes but is not limited to a liquid crystal display, a light emitting diode, a display and a plasma display. In some optional embodiments, the display device may be a touch screen.

[0202] The embodiment of the present invention also provides a computer-readable storage medium. The method according to the embodiment of the present invention can be implemented in hardware, firmware, or can be implemented as a computer code that can be recorded in a storage medium, or can be implemented as a computer code that is originally stored in a remote storage medium or a non-temporary machine-readable storage medium and will be stored in a local storage medium through a network download, so that the method described herein can be stored in such software processing on a storage medium using a general-purpose computer, a dedicated processor, or programmable or dedicated hardware. Among them, the storage medium can be a magnetic disk, an optical disk, a read-only storage memory, a random access memory, a flash memory, a hard disk or a solid-state hard disk, etc.; further, the storage medium can also include a combination of the above types of memories. It can be understood that a computer, a processor, a microprocessor controller, or programmable hardware includes a storage component that can store or receive software or computer code. When the software or computer code is accessed and executed by a computer, a processor, or hardware, the method shown in the above embodiment is implemented.

[0203] A part of the present invention may be applied as a computer program product, such as a computer program instruction, which, when executed by a computer, can call or provide the method and / or technical solution according to the present invention through the operation of the computer. Those skilled in the art should understand that the existence of the computer program instruction in a computer-readable medium includes, but is not limited to, a source file, an executable file, an installation package file, etc., and accordingly, the way in which the computer program instruction is executed by the computer includes, but is not limited to: the computer directly executes the instruction, or the computer compiles the instruction and then executes the corresponding compiled program, or the computer reads and executes the instruction, or the computer reads and installs the instruction and then executes the corresponding installed program. Here, the computer-readable medium may be any available computer-readable storage medium or communication medium accessible to the computer.

[0204] Although the embodiments of the present invention have been described in conjunction with the accompanying drawings, those skilled in the art may make various modifications and variations without departing from the spirit and scope of the present invention, and such modifications and variations are all within the scope defined by the appended claims.

Claims

1. A method for identifying rotating stall of a pump turbine, characterized in that: The method comprises: Acquire basic information and working status of the pump-turbine, wherein the basic information includes fluid density in the pump-turbine and structural information of the pump-turbine; Based on the basic information, a first water head difference, a second water head difference and a third water head difference are obtained, wherein the first water head difference is the water head difference of the pump-turbine inlet section, the second water head difference is the water head difference of the pump-turbine runner section, and the third water head difference is the water head difference of the pump-turbine outlet section; determining an overall water head difference of the pump turbine based on the first water head difference, the second water head difference and the third water head difference; Based on the overall water head difference, determining a critical point of a flow field disturbance stable state of the pump-turbine; Based on the working state and the critical point of the flow field disturbance stable state, it is determined whether the pump turbine is in rotational stall.

2. The method according to claim 1, characterized in that The obtaining of the first water head difference based on the basic information includes: Based on the basic information, determining the inlet section pressure information of the pump turbine, wherein the inlet section pressure information includes the inlet section inlet pressure, the undisturbed inlet section outlet pressure and the disturbed inlet section outlet pressure; Based on the inlet section pressure information, a first water head difference is determined.

3. The method according to claim 1, characterized in that The acquisition of the second water head difference includes: Based on the basic information, determining the hysteresis degree of the pump turbine; Based on the hysteresis degree, determining a first pressure difference and a second pressure difference of the runner section of the pump-turbine, wherein the first pressure difference is an inlet and outlet pressure difference of the runner section of the pump-turbine without disturbance, and the second pressure difference is an inlet and outlet pressure difference of the runner section of the pump-turbine with disturbance; Based on the first pressure difference and the second pressure difference, a second head difference is determined.

4. The method according to claim 3, characterized in that The determining a second water head difference based on the first pressure difference and the second pressure difference comprises: Based on the basic information and the first pressure difference, determining a first runner section water head expression, wherein the first runner section water head expression is a steady-state characteristic expression of the pump-turbine runner; Based on the basic information and the second pressure difference, determining a second runner section water head expression, wherein the second runner section water head expression is a steady-state characteristic expression and a hysteresis characteristic expression of the pump-turbine runner; Based on the first runner section water head expression and the second runner section water head expression, a second water head difference is determined.

5. The method according to claim 4, characterized in that The hysteresis characteristic expression is the product of the hysteresis characteristic function and the radial velocity change rate.

6. The method according to claim 1, characterized in that The acquisition of the third water head difference includes: Based on the basic information, construct the flow equation of the outlet section of the pump-turbine; Based on the flow equation, determining a first outlet section hydraulic head expression and a second outlet section hydraulic head expression; Based on the first outlet section hydraulic head expression and the second outlet section hydraulic head expression, a third hydraulic head difference is determined.

7. The method according to claim 1, characterized in that Determining the critical point of the flow field disturbance stable state of the pump-turbine based on the overall water head difference comprises: Performing complex decomposition on the overall water head difference to obtain the real part and imaginary part of the overall water head difference; Based on the real part of the difference and the imaginary part of the difference, a critical point of a flow field disturbance stable state of the pump-turbine is obtained.

8. A rotational stall identification device for a pump turbine, characterized in that: The device comprises: An information acquisition module, used to acquire basic information and working status of the pump-turbine, wherein the basic information includes fluid density in the pump-turbine and structural information of the pump-turbine; A segmented water head difference acquisition module, used for acquiring a first water head difference, a second water head difference and a third water head difference based on the basic information, wherein the first water head difference is the water head difference of the pump-turbine inlet section, the second water head difference is the water head difference of the pump-turbine runner section, and the third water head difference is the water head difference of the pump-turbine outlet section; an overall water head difference acquisition module, used for determining an overall water head difference of a pump-turbine based on the first water head difference, the second water head difference and the third water head difference; A critical point determination module, used for determining a critical point of a flow field disturbance stable state of the pump-turbine based on the overall water head difference; The rotating stall determination module is used to determine whether the pump turbine is rotating stalled based on the working state and the critical point of the flow field disturbance stable state.

9. A computer device, characterized in that: include: A memory and a processor, wherein the memory and the processor are communicatively connected to each other, the memory stores computer instructions, and the processor executes the method for identifying rotational stall of a pump-turbine according to any one of claims 1 to 7 by executing the computer instructions.

10. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores computer instructions, and the computer instructions are used to enable a computer to execute the method for identifying rotating stall of a pump-turbine according to any one of claims 1 to 7.

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