Hydropower station tail water system simulation method and ultralow frequency oscillation detection method

Abstract

The invention belongs to the field of hydropower station simulation, and particularly relates to a hydropower station tail water system simulation method and an ultralow frequency oscillation detection method.The simulation method comprises the steps that a flow channel structure of a hydropower station tail water system is obtained, and the flow channel structure comprises pipelines and connecting points; constructing an equivalent circuit topological graph according to the flow channel structure of the hydropower station tail water system; setting dynamic characteristic models of the pressure pipeline and the non-pressure open channel, and establishing an association relationship with the telegraph model; equivalently converting the structure parameters of the pipeline into pipeline circuit parameters of the circuit topology according to the incidence relation; equivalently converting the structure parameters of the connection points into connection point circuit parameters of the circuit topology, and taking the pipeline circuit parameters and the connection point circuit parameters as circuit topology parameters; and according to the circuit topological parameters and the circuit topological graph, establishing an equivalent simulation model of the hydropower station tail water system. The method has the effect of simply and accurately performing simulation calculation on the hydraulic model.

Description

Technical Field

[0001] The present invention belongs to the field of hydropower station simulation, and particularly relates to a simulation method for the tail water system of a hydropower station and a method for detecting ultra-low frequency oscillation. Background Art

[0002] Hydropower energy is a typical renewable energy, and its core development component is a hydropower unit. The tail water system of a hydropower unit is a key part of a hydropower station, mainly responsible for guiding the water flow that has passed through the water turbine back to the river or reservoir. Precise modeling through the tail water system is of great significance for analyzing the formation mechanism of the ultra-low frequency oscillation phenomenon of a hydropower station caused by the tail water system and engineering treatment measures for optimizing the hydropower unit.

[0003] Traditional hydraulic models are usually based on mathematical equations, which describe the hydrodynamic characteristics of water flow, the characteristic curves of water turbines, and the water conveyance characteristics of the tail water system, etc. These models are often complex and difficult to integrate with other systems. At the same time, these models may have limitations when dealing with complex working conditions and non-linear characteristics, and cannot accurately simulate and calculate the hydraulic model. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a simulation method for the tail water system of a hydropower station and a method for detecting ultra-low frequency oscillation, which can accurately and more simply simulate and calculate the hydraulic model, and detect whether there is ultra-low frequency oscillation in the hydropower station through this simulation model.

[0005] A simulation method for the tail water system of a hydropower station includes:

[0006] Obtain the flow channel structure of the tail water system of the hydropower station, where the flow channel structure includes pipelines and connection points;

[0007] Construct an equivalent circuit topology diagram according to the flow channel structure of the tail water system of the hydropower station;

[0008] Set the dynamic characteristic models of the pressure pipeline and the open channel without pressure, and establish an association relationship with the telegraph model;

[0009] According to the association relationship, equivalently convert the structural parameters of the pipeline into the pipeline circuit parameters of the circuit topology;

[0010] Equivalently convert the structural parameters of the connection point into the connection point circuit parameters of the circuit topology, and use the pipeline circuit parameters and the connection point circuit parameters as the circuit topology parameters;

[0011] Establish an equivalent simulation model for the tail water system of the hydropower station according to the circuit topology parameters and the circuit topology diagram.

[0012] Optionally, a dynamic characteristic model of a pressurized pipeline and an open channel is set, and the establishment of the correlation relationship with the telegraph model includes:

[0013] The dynamic characteristic model of the pressurized pipeline is expressed as:

[0014]

[0015] In the formula, g is the acceleration of gravity, and n c is the equivalent pipeline roughness corresponding to the comprehensive hydraulic loss after the local hydraulic loss on this section of the pipeline

[0016] n is the pipeline roughness corresponding to the frictional hydraulic loss of the pipeline, η is the local hydraulic loss coefficient, L is the pipeline length, S0 is the area of the bottom slope, R is the hydraulic radius, A is the cross-sectional area of flow, a is the water hammer wave velocity, H is the water pressure, Q is the water flow rate, x is the length variable, and t is the time variable;

[0017] The dynamic characteristic model of the open channel is expressed as:

[0018]

[0019] In the formula, B is the water surface width, v is the flow velocity, and H1 represents the water depth in the channel;

[0020] According to the telegraph model, the telegraph equation for the propagation of electromagnetic waves in a conductor is obtained, and the telegraph equation is expressed as:

[0021]

[0022] In the formula, R e , L e and C e are the resistance, inductance, and capacitance of the wire per unit length dx, U is the voltage, and I is the current;

[0023] According to the telegraph equation and the structural forms of the dynamic characteristic models of the pressurized pipeline and the open channel, a correlation relationship is established.

[0024] Optionally, according to the correlation relationship, the structural parameters of the pipeline are equivalently converted into pipeline circuit parameters of the circuit topology, including:

[0025] According to the correlation relationship, substituting the structural parameters of the pipeline into the telegraph equation, the equivalent circuit parameters of the pressurized pipeline and the equivalent circuit parameters of the open channel are obtained. The equivalent circuit parameters of the pressurized pipeline are:

[0026]

[0027] Among them, R e is the resistance, C e is the capacitance, and Le is an inductor;

[0028] The equivalent circuit parameters of an open channel without pressure are:

[0029]

[0030] C e = B

[0031]

[0032] Take the equivalent circuit parameters of the pressure pipeline and the equivalent circuit parameters of the open channel without pressure as the pipeline circuit parameters of the circuit topology.

[0033] Optionally, converting the structural parameters of the connection point into the connection point circuit parameters of the circuit topology includes:

[0034] The connection point includes a series connection point and a confluence connection point. The series connection point is the connection point where two pipelines are connected, and the confluence connection point is the connection point where three or more pipelines are connected;

[0035] According to the flow channel structure of the hydropower station tailrace system, obtain the continuity equation and the energy conservation equation of the two-side series openings;

[0036] The continuity equation and the energy conservation equation of the two-side series openings are expressed as:

[0037] Q1 = Q2

[0038]

[0039] In the formula, Q1, H1, and V1 are the flow rate, water pressure, and flow velocity at the outlet node of one side of the pipeline respectively, and Q2, H2, and V2 are the flow rate, water pressure, and flow velocity at the inlet node of the other side of the pipeline respectively;

[0040] Equivalent the continuity equation and the energy conservation equation of the two-side series openings to a two-port circuit, and calculate the equivalent resistance of the connection point;

[0041] The equivalent resistance of the connection point is expressed as:

[0042]

[0043] Among them, A1 and A2 respectively represent the flow-through areas of the outlet of one side of the pipeline and the inlet of the other side of the pipeline;

[0044] According to the flow channel structure of the hydropower station tailrace system, obtain the continuity equation and the energy conservation equation of the confluence point boundary of adjacent tailrace branch tunnels;

[0045] The continuity equation and the energy conservation equation of the confluence point boundary of adjacent tailrace branch tunnels are expressed as:

[0046]

[0047] Q1 = Q2 + Q3

[0048]

[0049] Wherein, H1 and H2 are the water pressures at the ends of two tailrace branch tunnels respectively, Q1 and Q2 are the flow rates at the ends of two tailrace branch tunnels respectively, V1 and V2 are the water flow velocities at the ends of two tailrace branch tunnels respectively, and H3, Q3 and V3 are the water pressure, flow rate and water flow velocity at the head of the main canal at the confluence point respectively;

[0050] Equivalent the continuity equation and energy conservation equation of the boundary of the confluence point of adjacent tailrace branch tunnels to two parallel branches, and the branch resistances R T1 and branch resistance R T2 After converging at the common node, and then passing through a series resistance R T3 represent;

[0051] The equivalent resistance calculation of its confluence point is:

[0052]

[0053] Regard the two-port circuit and the parallel branch as an equivalent circuit;

[0054] Regard the equivalent resistance of the connection point and the equivalent resistance of the confluence point as the connection point circuit parameters.

[0055] Optionally, according to the flow channel structure of the hydropower station tailrace system, constructing an equivalent circuit topology diagram includes:

[0056] According to the flow channel structure of the hydropower station tailrace system, obtain the connection point positions, pipeline positions and equivalent components corresponding to the connection points and pipelines;

[0057] Construct an equivalent circuit topology diagram according to the connection point positions, pipeline positions and equivalent components corresponding to the connection points and pipelines.

[0058] A hydropower station tailrace system simulation system, comprising:

[0059] An acquisition module, configured to acquire the flow channel structure of the hydropower station tailrace system, and the flow channel structure includes pipelines and connection points;

[0060] A construction module, configured to construct an equivalent circuit topology diagram according to the flow channel structure of the hydropower station tailrace system;

[0061] An association module, configured to set dynamic characteristic models of pressure pipelines and open channels without pressure, and establish an association relationship with the telegraph model;

[0062] A first conversion module, configured to equivalently convert the structural parameters of the pipeline into the pipeline circuit parameters of the circuit topology according to the association relationship;

[0063] A second conversion module, configured to convert the structural parameters of the connection point into the connection point circuit parameters of the circuit topology, and use the pipeline current parameters and the connection point circuit parameters as the circuit topology parameters;

[0064] A building module, configured to build an equivalent simulation model of the hydropower station tailrace system according to the circuit topology parameters and the circuit topology diagram.

[0065] A method for detecting ultra-low frequency oscillation of a hydropower station tailrace system, comprising:

[0066] Obtaining the initial parameters of the equivalent simulation model of the hydropower station tailrace system, and converting the initial parameters into circuit parameters, where the initial parameters include the stable flow rate of the pipeline, the water pressure at each part of the pipeline, and the pipeline resistance, and the equivalent simulation model of the hydropower station tailrace system is the equivalent simulation model of the hydropower station tailrace system obtained by the hydropower station tailrace system simulation method according to any one of claims 1-5;

[0067] Setting a simulation step size and a simulation solver;

[0068] Running the equivalent simulation model according to the set initial parameters, simulation step size and simulation solver to obtain the voltage waveform of the tailrace gate chamber section, where the tailrace gate chamber section is one of the water flow sections;

[0069] Determining whether ultra-low frequency oscillation occurs in the hydropower station tailrace system according to the voltage waveform of the tailrace gate chamber section.

[0070] Optionally, the determining whether ultra-low frequency oscillation occurs in the hydropower station tailrace system according to the voltage waveform of the tailrace gate chamber section includes:

[0071] Performing frequency domain analysis on the voltage waveform to obtain a frequency spectrum;

[0072] Searching for frequencies in the frequency spectrum and determining whether there are frequencies lower than a preset frequency;

[0073] If there are frequencies lower than the preset frequency, it is determined that ultra-low frequency oscillation occurs in the hydropower station tailrace system.

[0074] A terminal device, comprising a memory and a processor, where the memory stores a computer program capable of running on the processor, and when the processor loads and executes the computer program, a hydropower station tailrace system simulation method is adopted.

[0075] A computer-readable storage medium stores a computer program. When the computer program is loaded and executed by a processor, a simulation method for a hydropower station tailwater system is adopted.

[0076] The beneficial effects of the present invention are as follows:

[0077] 1. According to the flow channel structure of the hydropower station tailwater system, the actual hydraulic model is transformed into an equivalent circuit topology diagram. Then, dynamic characteristic models of pressure pipelines and open channels are set up and associated with the telegraph model. According to the association relationship, the structural parameters of the flow channel structure are equivalently transformed into circuit parameters of the circuit topology. Based on the circuit parameters and the circuit topology diagram, an equivalent simulation model of the hydropower station tailwater system is established. By introducing the circuit equivalence theory and using circuit elements in the Simscape circuit module library, the modeling process of the hydropower station tailwater system can be simplified. This method reduces the complex mathematical equations involved in the traditional hydraulic model, making the modeling more intuitive and efficient. Moreover, compared with the traditional mathematical equations, the simulation with the converted circuit model has more accurate simulation results.

[0078] 2. By selecting appropriate circuit elements and setting corresponding parameters, this method can capture the dynamic characteristics in the tailwater system, such as water head, flow rate, pressure, etc. This helps to improve the simulation accuracy, thereby more accurately evaluating the impact of the tailwater system on the operation of the hydropower station;

[0079] 3. It is applicable to different types of tailwater flow channels, including pressure pipelines and open channels, etc. This means that this method has wide applicability and can be applied to the modeling and simulation of various hydropower station tailwater systems.

[0080] 4. By performing simulation analysis on the tailwater system model based on Simscape circuits, the impact of the tailwater system on the operation of the hydropower station can be better understood. This helps to optimize the operation strategy, improve the power generation efficiency, and thus improve the economy and reliability of the hydropower station; this method can simulate the performance of the tailwater system under different working conditions, which helps to analyze the potential causes and impacts of faults. Through the analysis of the simulation results, potential problems can be discovered and prevented in advance, improving the safe operation of the hydropower station. Description of the Drawings

[0081] Figure 1 It is a schematic flow chart of a simulation method for a hydropower station tailwater system of the present invention;

[0082] Figure 2 It is an equivalent circuit schematic diagram of the flow channel structure of the hydropower station tailwater system of the present invention;

[0083] Figure 3 It is an equivalent circuit diagram of the transmission line of the present invention;

[0084] Figure 4 It is the equivalent circuit diagram of the connection point of the pipe (channel) boundary;

[0085] Figure 5 It is the equivalent circuit diagram of the confluence point;

[0086] Figure 6 It is the comparison curve of the water pressure oscillation in the tail gate chamber corresponding to two units in the tail water system;

[0087] Figure 7 It is the schematic diagram of the water pressure oscillation curve of the water pressure oscillation obtained by simulation and the measured curve. Specific implementation manner

[0088] This application uses Simscape for equivalent simulation. Simscape is a physics-based modeling tool that allows users to build models of multi-domain systems using a component-based approach. Simscape Electrical is a subset of Simscape dedicated to electrical system modeling. Using Simscape Electrical, it is convenient to model, simulate, and optimize multi-domain systems. This method uses circuit elements (such as resistors, inductors, capacitors, etc.) to simulate the dynamic characteristics of the hydraulic system, such as head, flow rate, pressure, etc. Such a method can not only simplify the construction and simulation of the model but also achieve seamless integration with other domains (such as mechanical, electrical, etc.).

[0089] A simulation method for the tail water system of a hydropower station, as Figure 1 shown, includes:

[0090] S1. Obtain the flow channel structure of the tail water system of the hydropower station, where the flow channel structure includes pipes and connection points.

[0091] Specifically, the tail water system of the hydropower station has multiple water flow segments. Each water flow segment includes a pipe and a connection point. The water flow segment itself is equivalent to a pipe, and the connection structure between adjacent water flow segments is equivalent to a connection point. In this embodiment, the water flow segments of the tail water system of the hydropower station include, from left to right, the tail water pipe outlet, the tail water connection section, the tail water gate chamber section, the type A lining section of the tail water branch canal, the branch canal connection point, the type B lining section of the tail water branch canal, the tail water confluence point, the tail water main canal, and the downstream river channel.

[0092] S2. Construct an equivalent circuit topology diagram according to the flow channel structure of the tail water system of the hydropower station.

[0093] Specifically, convert the flow channel structure of the physical tail water system of the hydropower station into a corresponding circuit structure to form a circuit topology diagram. If the flow channel structure is two side-by-side series openings, it is converted into a two-port circuit. If it is the confluence point of adjacent tail water branch tunnels, it is converted into two parallel branches. Using an analogical method, map the corresponding relationships between parameters such as pressure, flow rate, and resistance in the hydraulic system and parameters such as voltage, current, and resistance in the circuit.

[0094] S3. Set up the dynamic characteristic models of pressurized pipelines and open channels without pressure, and establish the correlation with the telegraph model.

[0095] Specifically, the telegraph model is the propagation law model of electromagnetic waves in conductors. The propagation law follows the famous telegraph equation and can be expressed by a system of partial differential equations.

[0096] Setting up the dynamic characteristic models of pressurized pipelines and open channels without pressure and establishing the correlation with the telegraph model includes:

[0097] Taking the water pressure H and the flow rate Q as state variables, the hydraulic dynamic characteristics of a pressurized pipe (tunnel) with an arbitrary cross-sectional shape can be expressed by a system of partial differential equations (i.e., the dynamic characteristic model of the pressurized pipeline):

[0098]

[0099] In the formula, g is the acceleration due to gravity, n c is the equivalent roughness coefficient of the comprehensive hydraulic loss after the local hydraulic loss on this section of the pipeline n is the roughness coefficient of the pipeline corresponding to the frictional hydraulic loss along the pipeline, η is the local hydraulic loss coefficient, L is the pipeline length, S0 is the area of the bottom slope, R is the hydraulic radius, A is the cross-sectional area of flow, a is the water hammer wave velocity, H is the water pressure, Q is the water flow rate, x is the length variable, and t is the time variable;

[0100] Taking the water pressure H and the flow rate Q as state variables, the hydraulic dynamic characteristics of an open channel (tunnel) with a rectangular, trapezoidal or lower rectangular section of the horseshoe-shaped cross-section can be deduced from the continuity equation and momentum equation of the open channel and can be expressed by a system of partial differential equations (i.e., the dynamic characteristic model of the open channel without pressure): It is expressed as:

[0101]

[0102] In the formula, B is the water surface width, v is the flow velocity, and H1 in this formula represents the water depth in the channel;

[0103] According to the telegraph model, obtain the telegraph equation for the propagation of electromagnetic waves in conductors. The telegraph equation is expressed as:

[0104]

[0105] In the formula,, R e , L e and C e are the resistance, inductance and capacitance of the wire per unit length dx respectively, U is the voltage, and I is the current;

[0106] Replace U and I in the circuit with H and Q, then the hydraulic dynamic characteristic equations of the pressure pipe and the open channel have the same structural form as the telegraph equation. Therefore, the hydraulic structure model can be transformed into a circuit model.

[0107] Establish the correlation relationship according to the structural forms of the telegraph equation, the dynamic characteristic models of the pressure pipe and the open channel.

[0108] Specifically, replace H and Q in the dynamic characteristic models of the pressure pipe and the open channel with U and I.

[0109] S4. Equivalently transform the structural parameters of the pipe into the pipe circuit parameters of the circuit topology according to the correlation relationship.

[0110] Specifically, when performing parameter transformation, different equivalent circuits will be converted according to different flow channel structures. Therefore, the equivalent parameters in different equivalent circuits are different.

[0111] Equivalently transforming the structural parameters of the pipe into the circuit parameters of the circuit topology according to the correlation relationship includes:

[0112] According to the correlation relationship, substitute the structural parameters of the pipe into the telegraph equation to obtain the equivalent circuit parameters of the pressure pipe and the open channel. The equivalent circuit parameters of the pressure pipe are:

[0113]

[0114] Among them, R e is the resistance, C e is the capacitance, L e is the inductance;

[0115] The equivalent circuit parameters of the open channel are:

[0116]

[0117] C e = B

[0118]

[0119] Take the equivalent circuit parameters of the pressure pipe and the open channel as the pipe circuit parameters of the circuit topology.

[0120] S5. Transform the structural parameters of the connection point into the connection point circuit parameters of the circuit topology, and take the pipe circuit parameters and the connection point circuit parameters as the circuit topology parameters.

[0121] Transforming the structural parameters of the connection point into the connection point circuit parameters of the circuit topology includes:

[0122] Based on the flow channel structure of the hydropower station tailrace system, the continuity equation and the energy conservation equation for the two-side series-connected openings are obtained;

[0123] The continuity equation and the energy conservation equation for the two-side series-connected openings are expressed as:

[0124] Q1 = Q2

[0125]

[0126] Where Q1, H1, and V1 are the flow rate, water pressure, and flow velocity at the outlet node of one side of the pipeline, respectively, and Q2, H2, and V2 are the flow rate, water pressure, and flow velocity at the inlet node of the other side of the pipeline, respectively;

[0127] The continuity equation and the energy conservation equation for the two-side series-connected openings are equivalent to a two-port circuit, and the equivalent resistance of the connection point is calculated;

[0128] The equivalent resistance of the connection point is expressed as:

[0129]

[0130] Where A1 and A2 represent the flow-through areas of the outlet of one side of the pipeline and the inlet of the other side of the pipeline, respectively;

[0131] Based on the flow channel structure of the hydropower station tailrace system, the continuity equation and the energy conservation equation for the confluence point boundary of adjacent tailrace branch tunnels are obtained; the continuity equation and the energy conservation equation for the confluence point boundary of adjacent tailrace branch tunnels are expressed as:

[0132]

[0133] Q1 = Q2 + Q3

[0134]

[0135] Where H1 and H2 are the water pressures at the ends of the two tailrace branch tunnels, Q1 and Q2 are the flow rates at the ends of the two tailrace branch tunnels, V1 and V2 are the flow velocities of the water at the ends of the two tailrace branch tunnels, and H3, Q3, and V3 are the water pressure (water head), flow rate, and flow velocity of the main channel at the confluence point, respectively;

[0136] The continuity equation and the energy conservation equation for the confluence point boundary of adjacent tailrace branch tunnels are equivalent to two parallel branches, and the branch resistances R T1 and the branch resistance R T2 After converging at the common node, and then passing through a series resistance R T3 are represented;

[0137] The equivalent resistance of its confluence point is calculated as:

[0138]

[0139] Take the two-port circuit and the parallel branch as an equivalent circuit.

[0140] Take the equivalent resistance of the connection point and the equivalent resistance of the confluence point as the circuit parameters of the connection point.

[0141] Specifically, the equivalent circuit after transformation is as Figure 2 shown.

[0142] According to the flow channel structure of the hydropower station tailrace system, construct an equivalent circuit topology diagram including:

[0143] According to the flow channel structure of the hydropower station tailrace system, obtain the connection point positions, pipeline positions, and equivalent components corresponding to the connection points and pipelines;

[0144] According to the connection point positions, pipeline positions, and equivalent components corresponding to the connection points and pipelines, construct an equivalent circuit topology.

[0145] Specifically, the connection points are the boundary connection points of the pipe (channel), and in addition to the connection points and confluence points, it also includes transmission lines. Figure 3 is the equivalent circuit diagram of the transmission line. Figure 4 is the equivalent circuit diagram of the boundary connection point of the pipe (channel). Figure 5 is the equivalent circuit diagram of the confluence point.

[0146] S6. According to the circuit topology parameters and the circuit topology diagram, establish an equivalent simulation model of the hydropower station tailrace system.

[0147] Since the equivalent parameters of different circuits have been calculated previously and the equivalent circuit diagram of the flow channel structure has been constructed, the circuit elements to be selected in the Simscape module library now include basic elements such as resistors, inductors, capacitors, and voltage sources. Select the SeriesRLCBranch element in the Simscape / Electrical / SpecializedPowerSystems / Passives directory of the Simulink component library and add it to Simulink. Then select the type of this element as "R", and the modeling selection of the resistor is completed. Select the SeriesRLCBranch element in the Simscape / Electrical / SpecializedPowerSystems / Passives directory of the Simulink component library and add it to Simulink. Then select the type of this element as "L", and the modeling selection of the inductor is completed; Select the SeriesRLCBranch element in the Simscape / Electrical / SpecializedPowerSystems / Passives directory of the Simulink component library and add it to Simulink. Then select the type of this element as "C", and the modeling selection of the capacitor is completed; Select the DCVoltageSource element in the Simscape / Electrical / SpecializedPowerSystems / Sources directory of the Simulink component library and add it to Simulink, and the modeling selection of the voltage source is completed.

[0148] Then connect the selected components in the order of the equivalent circuit topology diagram. At this time, the simulation model is established.

[0149] An ultra-low frequency vibration detection method for the tail water system of a hydropower station, including:

[0150] Obtain the initial parameters of the equivalent simulation model of the tail water system of the hydropower station and convert the initial parameters into circuit parameters. The initial parameters include the stable flow rate of the pipeline, the water pressure at each part of the pipeline, and the pipeline resistance. The equivalent simulation model of the tail water system of the hydropower station is obtained from the simulation method of the tail water system of the hydropower station;

[0151] Specifically, use the established equivalent simulation model of the tail water system of the hydropower station, set the initial parameters and then perform simulation operations. The initial parameters are the stable flow rate of the pipeline, the water pressure at each part of the pipeline, and the pipeline resistance during the actual operation of the hydropower station, and need to be converted into corresponding circuit parameters, and the circuit parameters are voltage, current, resistance, etc.

[0152] Set the simulation step size and the simulation solver;

[0153] Run the equivalent simulation model according to the set initial parameters, simulation step size, and simulation solver to obtain the voltage waveform of the tailrace gate chamber section;

[0154] Specifically, after setting the component parameters in each circuit, start the simulation to obtain the voltage waveform of the tailrace gate chamber section.

[0155] Determine whether ultra-low frequency oscillation occurs in the hydropower station tailrace system according to the voltage waveform of the tailrace gate chamber section.

[0156] Determining whether ultra-low frequency oscillation occurs in the hydropower station tailrace system according to the voltage waveform of the tailrace gate chamber section includes:

[0157] Conduct a frequency domain analysis of the voltage waveform to obtain the frequency spectrum;

[0158] Specifically, filter the collected water pressure signal to remove high-frequency noise and other interferences to highlight the low-frequency components, observe the time-domain waveform of the water pressure signal, look for signs of periodic changes, apply the fast Fourier transform (FFT) to the time-domain signal to convert the signal into the frequency domain, identify the frequency components, and search for the low-frequency components in the frequency spectrum, especially in the frequency range below 1 Hz, to determine whether ultra-low frequency oscillation exists.

[0159] Search for the frequencies in the frequency spectrum and determine whether there are frequencies below the preset frequency;

[0160] Specifically, the preset frequency is the minimum frequency for judging whether there is ultra-low frequency oscillation. In this embodiment, the preset frequency is 1 Hz.

[0161] If there are frequencies below the preset frequency, it is determined that ultra-low frequency oscillation occurs in the hydropower station tailrace system.

[0162] Specifically, to verify the simulation results, substitute the parameters in the structural view of the tailrace system of a large hydropower station into the embodiment. Solve the Simsacpe model of the equivalent circuit model built by Simulink through ode23t.

[0163] Simulation results Figure 6 As shown, through the comparison curve of the water pressure oscillation in the tailrace chambers corresponding to the two units in the tailrace system, it can be found that after the simulation reaches the preset stable operating condition through iterative calculation, the water pressure at the two tailrace chambers starts to oscillate periodically with equal amplitude centered around 7 m, the oscillation amplitude is about 0.1 m, the oscillation frequency is 0.043635 Hz, and the phase difference between the water pressure oscillations at the two tailrace chambers is about 180 degrees;

[0164] From Figure 7It can be seen that the water pressure oscillation obtained by simulation is compared with the water pressure oscillation of the measured curve. The water pressure oscillation frequency of the simulation is about 0.06 Hz and that of the measured curve is about 0.065 Hz, with a difference of 0.005 Hz between the two; the amplitudes of the water pressure oscillation in the simulation and the measured water pressure oscillation are about 0.11 m and 0.16 m respectively, with a difference of 0.05 m between the two. From these two sets of data, the simulation error is below 10%. Therefore, the model constructed based on Simscape can accurately reflect the hydraulic dynamic characteristics of the system and lay a model foundation for further analyzing the formation mechanism of the oscillation and seeking strategies to suppress the oscillation.

[0165] The simulation results show that the equivalent circuit modeling of the hydropower station tailrace system circuit constructed in this paper based on Simscape circuit can accurately reflect the hydraulic dynamic characteristics of the system and reproduce the periodic hydraulic oscillation phenomenon in the hydropower station tailrace system, laying a model foundation for further analyzing the formation mechanism of the oscillation and exploring oscillation suppression strategies, thus proving the correctness of the modeling method proposed in the embodiments of the present invention.

[0166] A simulation method for a hydropower station tailrace system, comprising:

[0167] An acquisition module, configured to acquire the flow channel structure of the hydropower station tailrace system;

[0168] A construction module, configured to construct an equivalent circuit topology diagram according to the flow channel structure of the hydropower station tailrace system, where the flow channel structure includes pipelines and connection points;

[0169] An association module, configured to set dynamic characteristic models for the pressurized pipeline and the open channel without pressure and establish an association relationship with the telegraph model;

[0170] A first conversion module, configured to equivalently convert the structural parameters of the pipeline into pipeline circuit parameters of the circuit topology according to the association relationship;

[0171] A second conversion module, configured to convert the structural parameters of the connection point into connection point circuit parameters of the circuit topology, and use the pipeline current parameters and the connection point circuit parameters as circuit parameters;

[0172] An establishment module, configured to establish an equivalent simulation model of the hydropower station tailrace system according to the circuit parameters and the circuit topology diagram.

[0173] An embodiment of the present application also discloses a terminal device, including a memory and a processor. The memory stores a computer program that can run on the processor. When the processor loads and executes the computer program, a simulation method for a hydropower station tailrace system is adopted.

[0174] Among them, the terminal device can be a computer device such as a desktop computer, a laptop computer, or a cloud server. Moreover, the terminal device includes, but is not limited to, a processor and a memory. For example, the terminal device may also include input / output devices, network access devices, and a bus, etc.

[0175] Among them, the processor can adopt a central processing unit (CPU). Of course, according to the actual usage situation, other general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. can also be adopted. The general-purpose processor can adopt a microprocessor or any conventional processor, etc. This application does not make any restrictions on this.

[0176] Among them, the memory can be an internal storage unit of the terminal device. For example, the hard disk or memory of the terminal device, or it can also be an external storage device of the terminal device. For example, a plug-in hard disk, a smart media card (SMC), a secure digital card (SD), or a flash card (FC), etc. equipped on the terminal device. Moreover, the memory can also be a combination of the internal storage unit and the external storage device of the terminal device. The memory is used to store computer programs and other programs and data required by the terminal device. The memory can also be used to temporarily store the data that has been output or will be output. This application does not make any restrictions on this.

[0177] Among them, through this terminal device, a simulation method for a hydropower station tailwater system in the above embodiment is stored in the memory of the terminal device, and is loaded and executed on the processor of the terminal device, which is convenient for use.

[0178] The embodiment of this application also discloses a computer-readable storage medium. Moreover, the computer-readable storage medium stores a computer program. Among them, when the computer program is executed by the processor, a simulation method for a hydropower station tailwater system in the above embodiment is adopted.

[0179] Among them, the computer program can be stored in a computer-readable medium. The computer program includes computer program code. The computer program code can be in the form of source code, object code, an executable file, or some middleware form, etc. The computer-readable medium includes any entity or device that can carry the computer program code, a recording medium, a USB flash drive, a mobile hard disk, a magnetic disk, an optical disc, a computer memory, a read-only memory (ROM), a random access memory (RAM), an electrical carrier signal, a telecommunication signal, and a software distribution medium, etc. It should be noted that the computer-readable medium includes, but is not limited to, the above components.

[0180] Among them, through this computer-readable storage medium, a simulation method for a hydropower station tail water system in the above embodiments is stored in the computer-readable storage medium, and is loaded and executed on a processor to facilitate the storage and application of the above method.

[0181] Those of ordinary skill in the art should understand that the discussion of any of the above embodiments is only exemplary and is not intended to imply that the scope of protection of this application is limited to these examples; under the concept of this application, the technical features in the above embodiments or different embodiments can also be combined, the steps can be implemented in any order, and there are many other variations in different aspects of one or more embodiments in this application as described above, and they are not provided in detail for the sake of brevity.

[0182] One or more embodiments of this application are intended to cover all such substitutions, modifications, and variations that fall within the broad scope of this application. Therefore, any omissions, modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of one or more embodiments of this application shall be included within the scope of protection of this application.

Claims

1. A method for simulating a tailwater system of a hydropower station, characterized in that: include: Acquire a flow channel structure of a tailwater system of a hydropower station, wherein the flow channel structure includes pipelines and connection points; According to the flow channel structure of the tailwater system of the hydropower station, an equivalent circuit topology diagram is constructed; Set up dynamic characteristic models of pressurized pipelines and unpressurized open channels, and establish correlations with telegraph models; According to the association relationship, the structural parameters of the pipeline are equivalently converted into pipeline circuit parameters of the circuit topology; Converting the structural parameters of the connection points into equivalent circuit parameters of the connection points of the circuit topology, and using the pipeline circuit parameters and the connection point circuit parameters as circuit topology parameters; According to the circuit topology parameters and the circuit topology diagram, an equivalent simulation model of the tailwater system of the hydropower station is established.

2. The hydropower station tailwater system simulation method according to claim 1, characterized in that: Setting up the dynamic characteristic model of the pressurized pipeline and the unpressurized open channel and establishing the relationship with the telegraph model includes: The dynamic characteristic model of the pressurized pipeline is expressed as: Where g is the acceleration due to gravity, n is c is the equivalent pipeline roughness corresponding to the comprehensive hydraulic loss after the local hydraulic loss on this section of the pipeline n is the pipeline roughness corresponding to the hydraulic loss along the pipeline, η is the local hydraulic loss coefficient, L is the pipeline length, S0 is the area of ​​the bottom slope, R is the hydraulic radius, A is the flow area, a is the water hammer wave velocity, H is the water pressure, Q is the water flow rate, x is the length variable, and t is the time variable; The dynamic characteristic model of the unpressured open channel is expressed as: In the formula, B is the width of the water surface, v is the flow velocity, and H1 represents the water depth in the channel; According to the telegraph model, the telegraph equation for the propagation of electromagnetic waves in a conductor is obtained, which is expressed as: In the formula, R e , L e and C e are the resistance, inductance and capacitance of the wire per unit length dx, U is the voltage, and I is the current; An association relationship is established based on the telegraph equation, the structural form of the dynamic characteristic model of the pressurized pipeline and the unpressurized open channel.

3. The hydropower station tailwater system simulation method according to claim 2, characterized in that: According to the association relationship, the pipeline structural parameters are equivalently converted into pipeline circuit parameters of the circuit topology, including: According to the association, the structural parameters of the pipeline are substituted into the telegraph equation to obtain the equivalent circuit parameters of the pressurized pipeline and the equivalent circuit parameters of the unpressurized open channel. The equivalent circuit parameters of the pressurized pipeline are: Among them, R e is the resistance, C e is the capacitance, L e is the inductor; The equivalent circuit parameters of the unpressurized open channel are: C e =B The equivalent circuit parameters of the pressurized pipeline and the equivalent circuit parameters of the unpressurized open channel are used as the pipeline circuit parameters of the circuit topology.

4. The hydropower station tailwater system simulation method according to claim 1, characterized in that: Converting the structural parameters of the connection point into the connection point circuit parameters of the circuit topology includes: The connection points include a series connection point and a confluence connection point. The series connection point is a connection point where two pipelines are connected, and the confluence connection point is a connection point where three or more pipelines are connected. According to the flow channel structure of the tailwater system of the hydropower station, the continuity equation and energy conservation equation of the series-connected openings on both sides are obtained; The continuity equation and energy conservation equation of the two-side series openings are expressed as: Q1=Q2 Where Q1, H1, and V1 are the flow rate, water pressure, and flow velocity at the outlet node of one side of the pipeline, respectively; Q2, H2, and V2 are the flow rate, water pressure, and flow velocity at the inlet node of the other side of the pipeline, respectively; The continuity equation and energy conservation equation of the holes in series on both sides are equivalent to a two-port circuit, and the equivalent resistance of the connection point is calculated; The equivalent resistance of the connection point is expressed as: Among them, A1 and A2 represent the flow areas of the pipe outlet on one side and the pipe inlet on the other side respectively; According to the flow channel structure of the tailwater system of the hydropower station, the continuity equation and energy conservation equation of the confluence point boundary of adjacent tailwater branch tunnels are obtained; The continuity equation and energy conservation equation of the confluence point boundary of adjacent tailwater tunnels are expressed as: Q1=Q2+Q3 Among them, H1 and H2 are the water pressure at the end of the two tailwater tunnels, Q1 and Q2 are the flow rates at the end of the two tailwater tunnels, V1 and V2 are the water flow rates at the end of the two tailwater tunnels, and H3, Q3 and V3 are the water pressure, flow rate and water flow rate at the head of the main channel of the confluence point respectively; The continuity equation and energy conservation equation of the confluence point boundary of adjacent tailwater branch tunnels are equivalent to two parallel branches. The branch resistance R of the two parallel branches is T1 And the branch resistance R T2 After the common node is connected, a series resistor R T3 express; The equivalent resistance of its confluence point is calculated as: The two-port circuit and the parallel branch are regarded as equivalent circuits; The equivalent resistance of the connection point and the equivalent resistance of the confluence point are used as connection point circuit parameters.

5. The hydropower station tailwater system simulation method according to claim 4, characterized in that: According to the flow channel structure of the tailwater system of the hydropower station, an equivalent circuit topology diagram is constructed including: According to the flow channel structure of the tailwater system of the hydropower station, the connection point position, the pipeline position and the equivalent components corresponding to the connection point and the pipeline are obtained; An equivalent circuit topology diagram is constructed based on the connection point locations, pipeline locations, and equivalent components corresponding to the connection points and pipelines.

6. A hydropower station tailwater system simulation system, comprising: An acquisition module, used to acquire a flow channel structure of a tailwater system of a hydropower station, wherein the flow channel structure includes pipes and connection points; A construction module, used to construct an equivalent circuit topology diagram according to the flow channel structure of the tailwater system of the hydropower station; The association module is used to set the dynamic characteristic model of the pressurized pipeline and the unpressurized open channel and establish an association relationship with the telegraph model; A first conversion module, used for converting the structural parameters of the pipeline into equivalent pipeline circuit parameters of the circuit topology according to the association relationship; A second conversion module is used to convert the structural parameters of the connection point into connection point circuit parameters of the circuit topology, and use the pipeline current parameters and the connection point circuit parameters as circuit topology parameters; A module is established to establish an equivalent simulation model of the tailwater system of the hydropower station according to the circuit topology parameters and the circuit topology diagram.

7. A method for detecting ultra-low frequency oscillation of a tailwater system of a hydropower station, characterized in that: include: Obtaining initial parameters of an equivalent simulation model of a tailwater system of a hydropower station, and converting the initial parameters into circuit parameters, wherein the initial parameters include a stable flow rate of a pipeline, water pressure at various locations in the pipeline, and pipeline resistance, wherein the equivalent simulation model of the tailwater system of a hydropower station is an equivalent simulation model of a tailwater system of a hydropower station obtained by the simulation method of a tailwater system of a hydropower station according to any one of claims 1 to 5; Set the simulation step size and simulation solver; Running the equivalent simulation model according to the set initial parameters, simulation step size and simulation solver to obtain a voltage waveform of a tailwater gate chamber section, wherein the tailwater gate chamber section is one of the water flow sections; According to the voltage waveform of the tailwater gate chamber section, it is determined whether ultra-low frequency oscillation occurs in the tailwater system of the hydropower station.

8. The method for detecting ultra-low frequency oscillation of a tailwater system of a hydropower station as claimed in claim 7, characterized in that: Determining whether ultra-low frequency oscillation occurs in the tailwater system of the hydropower station according to the voltage waveform of the tailwater gate chamber section includes: Performing frequency domain analysis on the voltage waveform to obtain a frequency spectrum; Find the frequency in the spectrum and determine whether there is a frequency lower than the preset frequency; If there is a frequency lower than the preset frequency, it is determined that ultra-low frequency oscillation occurs in the tailwater system of the hydropower station.

9. A terminal device, comprising a memory and a processor, characterized in that: The memory stores a computer program that can be run on the processor, and when the processor loads and executes the computer program, the method according to any one of claims 1 to 5 is adopted.

10. A computer-readable storage medium having a computer program stored therein, characterized in that: When the computer program is loaded and executed by a processor, the method according to any one of claims 1 to 5 is adopted.

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