Frequency modulation method, system, device and medium for geothermal unit

Abstract

This invention provides a frequency regulation method, system, equipment, and medium for geothermal units, belonging to the field of renewable energy power generation and power system automatic control. The method includes: real-time acquisition of temperature, pressure, and flow parameters at the geothermal wellhead; prediction of geothermal fluid characteristics over a future period using a multiphysics coupling model; calculation of the maximum frequency regulation capacity, ramp rate, and regulation accuracy of the geothermal unit under current and predicted operating conditions based on these parameters; and adjustment of the power generation control strategy and controller parameters according to the predicted values, adaptively switching on and off the automatic power generation control mode. By combining the multiphysics coupling model to predict fluid change trends, online evaluation of the unit's frequency regulation capability, and dynamic adjustment of the AGC control strategy and interaction method with the dispatching system, accurate evaluation and adaptive control of the geothermal unit's actual frequency regulation capability are achieved.

Description

Technical Field

[0001] This invention relates to the field of renewable energy power generation and power system automatic control technology, specifically to a frequency regulation method, system, equipment and medium for geothermal units. Background Technology

[0002] Automatic generation control (AGC) is a key technology for maintaining frequency stability and tie-line power exchange balance in power systems. With the increasing proportion of renewable energy generation, especially the integration of resource-dependent power sources such as geothermal power into the grid, new challenges are posed to AGC systems. Geothermal energy, as a stable, renewable, and clean energy source, plays an important role in the global energy structure. However, the output characteristics of geothermal power plants are significantly affected by geothermal fluid parameters (such as wellhead temperature, pressure, and flow rate), which decay or fluctuate with changes in operating time or geothermal reservoir conditions. For example, a decrease in the production temperature of the geothermal reservoir directly affects the net output power of the system, thereby altering the power generation cost and investment payback period of the geothermal unit.

[0003] Existing AGC systems typically rely on one of two modes to achieve frequency regulation of geothermal units: Fixed parameter reporting mode: Geothermal power plants report fixed regulation capacity and ramp rate to the dispatch system based on unit nameplate parameters or historical test data. This mode does not consider the time-varying nature of geothermal fluid parameters. When wellhead temperature / pressure naturally decays or fluctuates, the actual regulation capacity of the unit is lower than the reported value, resulting in unqualified AGC response and facing dispatch assessment. Permanent withdrawal from AGC mode: To avoid assessment risks, many geothermal power plants choose not to participate in AGC, operating only as baseload, thus losing ancillary service market revenue and wasting grid regulation resources.

[0004] In recent years, some studies have attempted to transplant the AGC (Automatic Generative Control) strategy of thermal power plants to geothermal units, but the following technical drawbacks exist: The lack of a dynamic mapping model between geothermal fluid parameters and unit frequency regulation capability makes it impossible to conduct online assessments of regulation capacity; the lack of predictive ability for geothermal fluid variation trends results in control strategies lagging behind parameter fluctuations; and the one-way, static information exchange between the unit and the dispatching system makes it impossible to dynamically report the true adjustable capacity. Summary of the Invention

[0005] The purpose of this invention is to provide a frequency regulation method, system, equipment, and medium for geothermal units. By collecting geothermal wellhead parameters in real time and combining them with a multiphysics coupling model to predict fluid change trends, the frequency regulation capability of the unit is evaluated online, and the AGC control strategy and interaction mode with the scheduling system are dynamically adjusted, thereby achieving accurate evaluation and adaptive control of the actual frequency regulation capability of the geothermal unit.

[0006] To achieve the above objectives, embodiments of the present invention provide a frequency regulation method for a geothermal unit, comprising: The temperature, pressure, and flow parameters at the geothermal wellhead are collected in real time; and the geothermal fluid characteristics are predicted over a period of time using a multiphysics coupling model. Based on the predicted geothermal fluid characteristics, the maximum frequency regulation capacity, ramp rate, and regulation accuracy of the geothermal unit under current and predicted operating conditions are calculated. Based on the maximum frequency regulation capacity, ramp rate, regulation accuracy index, and equipment safety constraints of the geothermal unit under current and predicted operating conditions, an adaptive switching automatic power generation control mode is implemented.

[0007] Optionally, the multiphysics coupling model includes at least the coupling of Fourier's heat conduction law and Darcy's fluid law, and integrates one or more of a two-phase flow model or a heat-fluid-solid coupling model to describe the heat transfer, seepage and phase change processes of geothermal fluids in reservoirs and wellbores.

[0008] Optionally, predict inland thermal fluid properties over a future period using a multiphysics coupling model, including: A heat conduction equation is established based on Fourier's law of heat conduction to describe the temperature field distribution of thermal reservoirs. A seepage equation is established based on Darcy's fluid law to describe the pressure field distribution of geothermal fluids in the porous medium of geothermal reservoirs. By coupling the heat conduction equation and the seepage equation, a heat-fluid coupling relationship is established; A two-phase flow model for the wellbore was established, and the pressure gradient inside the wellbore was calculated using the Orkiszewski method to describe the vapor-liquid two-phase flow and phase change process inside the wellbore. Using the pressure and temperature at the geothermal wellhead as the upper boundary conditions of the multiphysics coupling model, and the reservoir boundary pressure and reservoir boundary temperature as the lower boundary conditions, the multiphysics coupling model is discretized and solved using the finite difference method, and the predicted values ​​of wellhead pressure and wellhead temperature are output for a future period of time. The enthalpy of the geothermal fluid is calculated based on the predicted pressure and temperature at the wellhead.

[0009] Optionally, the enthalpy of the geothermal fluid can be calculated using the following formula:

[0010] In the formula, This indicates the predicted wellhead temperature. Indicates the specific enthalpy of saturated water. Indicates the latent heat of vaporization. Indicates the dryness of steam.

[0011] Optionally, the maximum frequency modulation capacity includes the maximum up-frequency modulation capacity and the maximum down-frequency modulation capacity; The maximum up-modulation capacity is calculated according to the following formula:

[0012] In the formula, η is the unit's heat-to-work conversion efficiency. The predicted enthalpy of the geothermal fluid at the wellhead. The predicted wellhead fluid flow rate is determined by the pressure gradient within the wellbore calculated based on a two-phase flow model. The lower limit of the fluid enthalpy required to maintain minimum stable operation of the unit. The minimum fluid mass flow rate required to maintain stable operation of the unit. For safety margin coefficient, This is the maximum capacity limit that can be increased.

[0013] The maximum down-regulation capacity is determined based on one or more of the following constraints: the lower limit flow rate constraint for safe operation of geothermal wellhead anti-scaling, the lower limit exhaust pressure constraint for safe operation of turbine, and the lower limit speed constraint for safe operation of working fluid pump. The lower limit flow rate constraint for safe operation of geothermal wellhead anti-scaling is determined based on the product of the predicted enthalpy of geothermal fluid and the lower limit flow rate for safe operation of anti-scaling.

[0014] Optionally, the adaptive automatic power generation control mode includes: The relationship between the unit's frequency regulation capability index and equipment safety constraints is determined in real time, and the determination result is obtained. The unit's frequency regulation capability index includes the maximum frequency regulation capacity, ramp rate, and regulation accuracy index. Based on the judgment result, it will automatically switch to one of the following modes: full-function participation mode, limited-amplitude participation mode, send-only-no-adjustment mode, or exit AGC mode. The current mode identifier is sent to the scheduling system, and the control strategy under the corresponding mode is executed.

[0015] Optionally, based on the judgment result, the system can automatically switch to one of the following modes: full-function participation mode, limited participation mode, send-only-no-adjustment mode, or exit AGC mode, including: The equipment safety constraints include a first threshold characterizing the upper limit of the maximum up-frequency modulation capacity, a second threshold characterizing the upper limit of the maximum down-frequency modulation capacity, a third threshold characterizing the upper limit of the ramp rate, and a fourth threshold characterizing the upper limit of the ramp rate adjustment accuracy. When the maximum up-frequency modulation capacity is greater than or equal to the first threshold, the maximum down-frequency modulation capacity is greater than or equal to the second threshold, the ramp rate is greater than or equal to the third threshold, and the adjustment accuracy is less than or equal to the fourth threshold, switch to full-function participation mode. When any of the following indicators—maximum up-frequency modulation capacity, maximum down-frequency modulation capacity, ramp rate, or adjustment accuracy—is lower than the corresponding threshold but higher than the corresponding lower limit, switch to amplitude limiting participation mode. When the maximum up-modulation capacity or the maximum down-modulation capacity is lower than the corresponding lower limit, switch to transmit-only mode; When wellhead parameters drop suddenly or the turbine trips, switch to exit AGC mode.

[0016] Secondly, the present invention also provides a frequency regulation system for a geothermal unit, comprising: The data acquisition module is used to collect temperature, pressure and flow parameters at the geothermal wellhead in real time; and to predict geothermal fluid characteristics over a period of time through a multiphysics coupling model. The frequency regulation capability assessment module is used to calculate the maximum frequency regulation capacity, ramp rate, and regulation accuracy of the geothermal unit under current and predicted operating conditions based on the predicted geothermal fluid characteristic values. The parameter adjustment module is used to adaptively switch on and off automatic power generation control modes based on the maximum frequency regulation capacity, ramp rate, regulation accuracy index, and equipment safety constraints of the geothermal unit under current and predicted operating conditions.

[0017] Thirdly, the present invention also provides an electronic device, including a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the program to implement the steps of the frequency regulation method of the geothermal unit described above.

[0018] Fourthly, the present invention also provides a storage medium storing a computer program thereon, which, when executed by a processor, implements the steps of the frequency regulation method for the geothermal unit described above.

[0019] The above technical solution involves real-time monitoring of key parameters at the geothermal wellhead, combined with a multiphysics coupling model to predict the changing trends of geothermal fluid characteristics, and online calculation of the maximum frequency regulation capacity and ramp-up rate of the geothermal unit. Based on the prediction results, the AGC controller dynamically adjusts the control strategy and parameters, and adaptively reports the unit's adjustable capacity to the power dispatching system, thereby improving the stability of power generation and the accuracy of grid frequency regulation.

[0020] Other features and advantages of the embodiments of the present invention will be described in detail in the following detailed description section. Attached Figure Description

[0021] The accompanying drawings are provided to further illustrate embodiments of the present invention and form part of the specification. They are used together with the following detailed description to explain the embodiments of the present invention, but do not constitute a limitation thereof. In the drawings: Figure 1This is a flowchart of a frequency regulation method for a geothermal unit provided in an embodiment of the present invention; Figure 2 This is a schematic diagram of the structure of a frequency regulation system for a geothermal unit provided in an embodiment of the present invention; Figure 3 This is a schematic diagram of the hardware structure of an electronic device provided in an embodiment of the present invention. Detailed Implementation

[0022] Various embodiments of this disclosure will be described more fully in the following detailed description. This disclosure may have various embodiments, and adjustments and changes may be made therein. However, it should be understood that there is no intention to limit the various embodiments of this disclosure to the specific embodiments disclosed herein, but rather this disclosure should be understood to cover all adjustments, equivalents, and / or alternatives falling within the spirit and scope of the various embodiments of this disclosure.

[0023] In the following, the terms “comprising” or “may include”, which may be used in various embodiments of this disclosure, indicate the presence of the disclosed functions or operations and do not limit the addition of one or more functions or operations. Furthermore, as used in various embodiments of this disclosure, the terms “comprising,” “having,” and their cognates are intended only to indicate a specific feature, number, step, operation, or combination of the foregoing and should not be construed as primarily excluding the presence of one or more other features, numbers, steps, operations, or combinations of the foregoing, or the possibility of adding one or more features, numbers, steps, operations, or combinations of the foregoing.

[0024] In various embodiments of this disclosure, the expression "or" or "at least one of A and / or B" includes any combination or all combinations of the words listed simultaneously. For example, the expression "A or B" or "at least one of A and / or B" may include A, may include B, or may include both A and B.

[0025] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0026] See Figure 1 The diagram shows a flowchart of a frequency regulation method for a geothermal unit in a specific embodiment, including the following execution steps: Step 100: Real-time acquisition of temperature, pressure, and flow parameters at the geothermal wellhead; and prediction of geothermal fluid characteristics over a future period using a multiphysics coupling model.

[0027] The multiphysics coupling model includes at least the coupling of Fourier's heat conduction law and Darcy's fluid law, and integrates one or more of a two-phase flow model or a heat-fluid-solid coupling model to describe the heat transfer, seepage and phase change processes of geothermal fluids in reservoirs and wellbores.

[0028] Key parameters for geothermal wellheads also include: wellhead steam / hot water temperature (°C), steam dryness (applicable to flash power plants), and non-condensable gas content.

[0029] Specifically, when executing step 100, the following steps can be performed: S1000: Based on Fourier's law of heat conduction, a heat conduction equation is established to describe the temperature field distribution of thermal reservoirs.

[0030] Specifically, the heat conduction equation is as follows:

[0031] In the formula, ρ represents rock density, c represents rock specific heat capacity, T represents reservoir temperature, t represents time, λ represents thermal conductivity, and Q represents the heat source term, which characterizes the influence of geothermal fluid convection heat transfer on the temperature field.

[0032] S1001: Based on Darcy's fluid law, a seepage equation is established to describe the pressure field distribution of geothermal fluids in the porous medium of the geothermal reservoir.

[0033] Specifically, the seepage equation is as follows:

[0034] In the formula, k represents reservoir permeability, μ represents hydrodynamic viscosity, P represents reservoir pressure, Φ represents porosity, and c t This represents the overall compression coefficient.

[0035] S1002: By coupling the heat conduction equation and the seepage equation, a heat-flow coupling relationship is established.

[0036] Specifically, the heat-fluid coupling relationship is as follows:

[0037] In the formula, For fluid density, Specific heat capacity of the fluid It is the dot product of the pressure gradient and the temperature gradient, characterizing the thermal transport effect of pressure-driven fluid flow on the temperature field.

[0038] S1003: Establish a two-phase flow model in the wellbore and use the Orkiszewski method to calculate the pressure gradient inside the wellbore to describe the vapor-liquid two-phase flow and phase change process inside the wellbore.

[0039] Specifically, the two-phase flow model in the wellbore is as follows:

[0040] In the formula, P represents the wellbore pressure, and z represents the wellbore depth. Indicates frictional resistance. Let g represent the density of the two-phase mixture, g represent the acceleration due to gravity, and θ represent the wellbore inclination angle. Indicates the flow rate of the mixture. This indicates the apparent flow rate in the gas phase.

[0041] S1004: Using the pressure and temperature at the geothermal wellhead as the upper boundary conditions of the multiphysics coupling model, and the reservoir boundary pressure and temperature as the lower boundary conditions, the multiphysics coupling model is discretized and solved using the finite difference method, and the predicted values ​​of the wellhead pressure and temperature are output for a future period of time.

[0042] In one specific embodiment, the multiphysics coupling model adopts a one-dimensional radial thermal reservoir-wellbore coupling model, which is spatially discretized along the geothermal fluid flow direction (reservoir radial to wellbore axial direction). The finite difference method is used to numerically solve the governing equations. The specific steps are as follows: S10040: Spatial discretization and mesh generation.

[0043] Specifically, the thermal reservoir is divided radially into There are 1 grid node, with a node spacing of 1. The wellbore is divided along the axial direction (depth direction) into... There are nodes, and the distance between the nodes is . The reservoir and wellbore are coupled at the bottom of the well, forming a unified discretized computational domain. For the reservoir region, the control volume method in radial coordinates is used for discretization; for the wellbore region, axial one-dimensional discretization is used.

[0044] S10041: Set boundary conditions.

[0045] Specifically, the upper boundary condition (wellhead): The real-time collected wellhead pressure and temperature are used as the upper boundary condition of the model and applied to the top nodes of the wellbore axial mesh.

[0046]

[0047] In the formula, Indicates wellhead pressure, This indicates the wellhead temperature.

[0048] Lower boundary conditions (reservoir boundary): Reservoir boundary pressure and reservoir boundary temperature are used as the lower boundary conditions of the model and applied to the outer boundary of the reservoir radial grid.

[0049]

[0050] In the formula, Pres is the reservoir boundary pressure and Tres is the reservoir boundary temperature.

[0051] The multiphysics coupling model is as follows:

[0052] S10042: Discretization of the governing equations.

[0053] Specifically, the heat conduction equation is discretized using an implicit scheme to discretize the heat conduction equation over time, in order to avoid time step limitations:

[0054] Discretize the spatial derivative term using the central difference scheme:

[0055] The seepage equation is discretized using an implicit scheme and central difference:

[0056] The spatially discrete form is similar to the heat conduction equation, forming a system of linear equations about the pressure field.

[0057] Coupling terms Explicit processing is used, utilizing the pressure and temperature fields from the previous time step for calculation, thus avoiding the solution complexity caused by nonlinear coupling:

[0058] Discretization of the wellbore two-phase flow model, for the wellbore two-phase flow pressure gradient equation:

[0059] The forward Euler method is used to integrate along the wellbore axis, advancing from the bottom of the well to the wellhead. At each spatial step Δz, the pressure drop ΔP within that step is calculated based on the pressure, temperature, and steam dryness of the current node, and the process is iteratively updated until convergence.

[0060] S10043: Time progression and solution process.

[0061] A time step Δt is set, and a fully implicit sequential coupling method is used for time advancement: the pressure field and temperature field at the current moment are used as initial conditions, the real-time wellhead parameters are used as upper boundary conditions, and the reservoir boundary parameters are used as lower boundary conditions. The seepage equation is solved to obtain the pressure field at the next moment; the heat-fluid coupling term is calculated based on the new pressure field, and the heat conduction equation is solved to obtain the temperature field at the next moment. The bottom hole pressure, temperature, and dryness obtained from the reservoir calculation are used as boundary conditions, and the wellbore two-phase flow model is solved by integrating upwards along the wellbore to update the wellbore pressure and temperature distribution; convergence is checked, and if the convergence condition is not met, the above steps of solving the heat conduction equation are returned for iteration until the prediction time endpoint. S1005: Calculate the enthalpy of the geothermal fluid based on the predicted pressure and temperature at the wellhead.

[0062] Specifically, the enthalpy of the geothermal fluid is calculated using the following formula:

[0063] In the formula, This indicates the predicted wellhead temperature. Indicates the specific enthalpy of saturated water. Indicates the latent heat of vaporization. Indicates the dryness of steam.

[0064] Step 101: Based on the predicted geothermal fluid characteristic values, calculate the maximum frequency regulation capacity, ramp rate, and regulation accuracy of the geothermal unit under the current and predicted operating conditions.

[0065] Specifically, the maximum frequency modulation capacity includes the maximum up-frequency modulation capacity and the maximum down-frequency modulation capacity; The maximum up-modulation capacity is calculated according to the following formula:

[0066] In the formula, η is the unit's heat-to-work conversion efficiency. The predicted enthalpy of the geothermal fluid at the wellhead. The predicted wellhead fluid flow rate is determined by the pressure gradient within the wellbore calculated based on a two-phase flow model. The lower limit of the fluid enthalpy required to maintain minimum stable operation of the unit. The minimum fluid mass flow rate required to maintain stable operation of the unit. For safety margin coefficient, This is the maximum capacity limit that can be increased.

[0067] The maximum down-regulation capacity is determined based on one or more of the following constraints: the lower limit flow rate constraint for safe operation of geothermal wellhead anti-scaling, the lower limit exhaust pressure constraint for safe operation of turbine, and the lower limit speed constraint for safe operation of working fluid pump. The lower limit flow rate constraint for safe operation of geothermal wellhead anti-scaling is determined based on the product of the predicted enthalpy of geothermal fluid and the lower limit flow rate for safe operation of anti-scaling.

[0068] The ramp rate includes the upward ramp rate: the rate at which the unit's output can be increased per unit time, and the downward ramp rate: the rate at which the unit's output can be decreased per unit time. In one specific implementation, the ramp rate R_up(t) is adjusted by the margin between the current valve opening V(t) and the maximum valve opening V_max. R_up(t) = min(R_up_nom, (V_max - V(t)) × K_v) Where R_up_nom is the rated ramp rate (1.8%Pn / min), K_v is the valve-power gain coefficient, and Pn represents the rated active power.

[0069] Adjustment accuracy ε(t): The root mean square deviation between the AGC command and the actual power output over the past 30 minutes is taken, with a target value ε≤1.0%Pn.

[0070] Step 102: Based on the maximum frequency regulation capacity, ramp rate, regulation accuracy index and equipment safety constraints of the geothermal unit under current and predicted operating conditions, adopt an adaptive switching automatic power generation control mode.

[0071] Specifically, the adaptive automatic power generation control mode includes: The system can determine the relationship between the unit's frequency regulation capability indicators and equipment safety constraints in real time and obtain the determination results. The unit's frequency regulation capability indicators include maximum frequency regulation capacity, ramp rate, and regulation accuracy indicators. Based on the determination results, the system can automatically switch to one of the following modes: full-function participation mode, limited-amplitude participation mode, power generation without regulation mode, or exit AGC mode. The system can send the current mode identifier to the dispatching system and execute the control strategy under the corresponding mode.

[0072] The equipment safety constraints include a first threshold representing the upper limit of the maximum up-frequency modulation capacity, a second threshold representing the upper limit of the maximum down-frequency modulation capacity, a third threshold representing the upper limit of the ramp rate, and a fourth threshold representing the upper limit of the ramp rate adjustment accuracy. When the maximum up-frequency modulation capacity is greater than or equal to the first threshold, the maximum down-frequency modulation capacity is greater than or equal to the second threshold, the ramp rate is greater than or equal to the third threshold, and the adjustment accuracy is less than or equal to the fourth threshold, the system switches to full-function participation mode A. When any one of the indicators of maximum up-frequency modulation capacity, maximum down-frequency modulation capacity, ramp rate, or adjustment accuracy is lower than the corresponding threshold but greater than the corresponding lower limit, the system switches to amplitude-limited participation mode B. When the maximum up-frequency modulation capacity or maximum down-frequency modulation capacity is lower than the corresponding lower limit, the system switches to transmission-only mode C. When the wellhead parameters drop sharply or the turbine trips, the system switches to exit AGC mode D.

[0073] For example, the ramp rate limiter: The AGC target power issued by the scheduler is processed through a first-order inertial element, and the inertial time constant τ is dynamically calculated based on the ramp rate R_up(t). τ = (P_target - P_cur) / R_up(t) When P_target - P_cur > 0, R_up(t) is used; otherwise, R_down(t) is used.

[0074] Wellhead pressure feedforward compensator: When the wellhead main pipe pressure drop rate dP / dt is detected to be less than -0.005 MPa / min and the duration exceeds 30 seconds, the regulating valve opening feedforward increment ΔV is automatically set to +2% to maintain stable steam flow.

[0075] In this embodiment, the AGC mode switching threshold is as follows: Mode A: ΔP_up ≥ 3MW and ΔP_down ≥ 3MW and R_up ≥ 0.3MW / min and ε ≤ 1.0%Pn; Mode B: 3MW>ΔP_up ≥ 1.5MW, 3MW>ΔP_down ≥ 1.5MW, but R_up or ε does not satisfy the conditions of Mode A; Mode C: ΔP_up < 1.5MW or ΔP_down < 1.5MW; Mode D: Wellhead pressure is below 0.45 MPa or turbine trips.

[0076] Every 5 minutes, the system sends a data packet on the unit's adjustable capacity to the provincial dispatch AGC master station via the IEC 60870-5-104 protocol. The data packet includes: increase standby capacity, decrease standby capacity, increase ramp rate, decrease ramp rate, and current AGC mode.

[0077] In this embodiment, by real-time monitoring of key parameters at the geothermal wellhead and combining this with a multiphysics coupling model to predict the changing trends of geothermal fluid characteristics, the maximum frequency regulation capacity and ramp-up rate of the geothermal unit are calculated online. Based on the prediction results, the AGC controller dynamically adjusts the control strategy and parameters, and adaptively reports the unit's adjustable capacity to the power dispatching system, thereby improving the stability of power generation and the accuracy of grid frequency regulation.

[0078] It should be understood that the sequence number of each step in the above embodiments does not imply the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present invention.

[0079] The technical effects achieved by this application are as follows: Precise assessment: For the first time, a multiphysics coupling model was introduced into the assessment of the frequency regulation capability of geothermal units, enabling accurate prediction of the time-varying nature of geothermal fluid parameters and real-time calculation of parameters such as maximum frequency regulation capacity, ramp rate, and regulation accuracy; Advanced compensation: Based on the prediction results, the AGC feedforward compensation strategy shortens the response delay of the geothermal unit to wellhead parameter fluctuations; Dynamic reporting: Enables two-way intelligent interaction between geothermal units and the dispatch system, allowing units to dynamically update and report their true adjustable capacity, thus improving accuracy.

[0080] like Figure 2 As shown, the following are embodiments of the frequency regulation system of the geothermal unit provided in this disclosure. The frequency regulation method of the geothermal unit in the above embodiments belongs to the same inventive concept. For details not described in detail in the embodiments of the frequency regulation system of the geothermal unit, please refer to the embodiments of the frequency regulation method of the geothermal unit described above.

[0081] A frequency regulation system for a geothermal unit, comprising: The data acquisition module is used to collect temperature, pressure and flow parameters at the geothermal wellhead in real time; and to predict geothermal fluid characteristics over a period of time through a multiphysics coupling model. The frequency regulation capability assessment module is used to calculate the maximum frequency regulation capacity, ramp rate, and regulation accuracy of the geothermal unit under current and predicted operating conditions based on the predicted geothermal fluid characteristic values. The parameter adjustment module is used to adaptively switch on and off automatic power generation control modes based on the maximum frequency regulation capacity, ramp rate, regulation accuracy index, and equipment safety constraints of the geothermal unit under current and predicted operating conditions.

[0082] Figure 3 This is a schematic diagram of the hardware structure of an electronic device that implements various embodiments of the present invention.

[0083] The frequency regulation method for geothermal units provided in this application can be applied to electronic devices. Those skilled in the art will understand that the electronic device structure involved in the embodiments of this invention does not constitute a limitation on the electronic device. An electronic device may include more or fewer components than illustrated, or combine certain components, or have different component arrangements. In the embodiments of this invention, the electronic device includes, but is not limited to, laptop computers, desktop computers, workbenches, personal digital assistants, servers, blade servers, mainframe computers, and other suitable computers. The electronic device may also represent various forms of mobile devices, such as personal digital processors, cellular phones, smartphones, wearable devices, and other similar computing devices. The components shown herein, their connections and relationships, and their functions are merely examples and are not intended to limit the implementation of the embodiments of this application described and / or claimed herein.

[0084] Electronic devices may include processors, external memory interfaces, internal memory, universal serial bus (USB) interfaces, charging management modules, power management modules, batteries, wireless communication modules, audio modules, speakers, microphones, sensor modules, buttons, cameras, displays, and SIM card interfaces, etc.

[0085] It is understood that the structures illustrated in the embodiments of this application do not constitute a specific limitation on the electronic device. In other embodiments of this application, the electronic device may include more or fewer components than illustrated, or combine some components, or split some components, or have different component arrangements. The illustrated components may be implemented in hardware, software, or a combination of software and hardware.

[0086] A processor may include one or more processing units, such as: a central processing unit (CPU), an application processor (AP), a modem processor, a graphics processing unit (GPU), an image signal processor (ISP), a controller, memory, a video codec, a digital signal processor (DSP), a baseband processor, and / or a neural network processing unit (NPU). Different processing units may be independent devices or integrated into one or more processors.

[0087] The processor can serve as the nerve center and command center of an electronic device. The controller can generate operation control signals based on the instruction opcode and timing signals to control the fetching and execution of instructions.

[0088] The processor may also include memory for storing instructions and data. In some embodiments, the memory in the processor is a cache memory. This memory can store instructions or data that the processor has just used or that are used repeatedly. If the processor needs to use the instruction or data again, it can retrieve it directly from this memory. This avoids repeated accesses, reduces processor latency, and thus improves system efficiency.

[0089] An external storage interface (ESI) can be used to connect external memory cards, such as microSD cards, to expand the storage capacity of electronic devices. The external memory card communicates with the processor through the ESI to perform data storage functions, such as saving music and video files on the external memory card.

[0090] Internal memory can be used to store computer executable program code, which includes instructions. The processor executes various functional applications and data processing of electronic devices by running the instructions stored in internal memory. Internal memory can include a program storage area and a data storage area. Internal memory can include high-speed random access memory, and can also include non-volatile memory, such as at least one disk storage device, flash memory device, universal flash storage (UFS), etc.

[0091] Wireless communication functionality in electronic devices can be achieved through antennas, wireless communication modules, modem processors, and baseband processors.

[0092] Wireless communication modules can provide solutions for wireless communication applications in electronic devices, including wireless local area networks (WLANs) (such as wireless fidelity (Wi-Fi) networks), Bluetooth (BT), global navigation satellite system (GNSS), frequency modulation (FM), near field communication (NFC), and infrared (IR) technologies.

[0093] Electronic devices can implement audio functions through audio modules, speakers, receivers, microphones, headphone jacks, and application processors.

[0094] Electronic devices can achieve shooting functions through ISPs, cameras, video codecs, GPUs, displays, and application processors.

[0095] Electronic devices can achieve display functions through GPUs, displays, and application processors.

[0096] A GPU is a microprocessor for image processing, connected to the display screen and application processor. GPUs are used to perform mathematical and geometric calculations for graphics rendering. A processor may include one or more GPUs, which execute program instructions to generate or modify display information.

[0097] A display screen is used to display images, videos, etc. A display screen includes a display panel.

[0098] The storage medium provided in this application stores a program product capable of implementing a frequency regulation method for geothermal units.

[0099] The frequency regulation method for geothermal units includes: real-time acquisition of temperature, pressure, and flow parameters at the geothermal wellhead; prediction of geothermal fluid characteristics over a future period using a multiphysics coupling model; calculation of the maximum frequency regulation capacity, ramp rate, and regulation accuracy of the geothermal unit under current and predicted operating conditions based on the predicted geothermal fluid characteristics; and adaptive switching of automatic power generation control mode based on the maximum frequency regulation capacity, ramp rate, regulation accuracy, and equipment safety constraints of the geothermal unit under current and predicted operating conditions.

[0100] In some possible implementations, the subject matter of this disclosure, namely the frequency regulation method and system for geothermal units, can be implemented as a program product including program code that, when the program product is run on a terminal device, causes the terminal device to perform the steps described in the "Exemplary Methods" section of this specification according to various exemplary embodiments of this disclosure.

[0101] The storage medium disclosed herein may be any combination of one or more readable media. A readable medium may be a readable signal medium or a readable storage medium. A readable storage medium may be, for example, but not limited to, an electrical, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any combination thereof. More specific examples (a non-exhaustive list) of readable storage media include: an electrical connection having one or more wires, a portable disk, a hard disk, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM or flash memory), optical fiber, portable compact disk read-only memory (CD-ROM), optical storage device, magnetic storage device, or any suitable combination thereof.

[0102] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method of frequency regulation of a geothermal unit, characterized in that, include: Real-time acquisition of temperature, pressure, and flow parameters at the geothermal wellhead; And predict the thermal fluid characteristics of the inland area in the near future using a multiphysics coupling model; Based on the predicted geothermal fluid characteristics, the maximum frequency regulation capacity, ramp rate, and regulation accuracy of the geothermal unit under current and predicted operating conditions are calculated. Based on the maximum frequency regulation capacity, ramp rate, regulation accuracy index, and equipment safety constraints of the geothermal unit under current and predicted operating conditions, an adaptive switching automatic power generation control mode is implemented.

2. The frequency modulation method of the geothermal unit according to claim 1, wherein, The multiphysics coupling model includes at least the coupling of Fourier's heat conduction law and Darcy's fluid law, and integrates one or more of a two-phase flow model or a heat-fluid-solid coupling model to describe the heat transfer, seepage and phase change processes of geothermal fluids in reservoirs and wellbores.

3. The frequency regulation method for a geothermal unit according to claim 2, characterized in that, Predicting inland thermal fluid properties over a future period using a multiphysics coupling model, including: A heat conduction equation is established based on Fourier's law of heat conduction to describe the temperature field distribution of thermal reservoirs. A seepage equation is established based on Darcy's fluid law to describe the pressure field distribution of geothermal fluids in the porous medium of geothermal reservoirs. By coupling the heat conduction equation and the seepage equation, a heat-fluid coupling relationship is established; A two-phase flow model for the wellbore was established, and the pressure gradient inside the wellbore was calculated using the Orkiszewski method to describe the vapor-liquid two-phase flow and phase change process inside the wellbore. Using the pressure and temperature at the geothermal wellhead as the upper boundary conditions of the multiphysics coupling model, and the reservoir boundary pressure and reservoir boundary temperature as the lower boundary conditions, the multiphysics coupling model is discretized and solved using the finite difference method, and the predicted values ​​of wellhead pressure and wellhead temperature are output for a future period of time. The enthalpy of the geothermal fluid is calculated based on the predicted pressure and temperature at the wellhead.

4. The frequency regulation method for a geothermal unit according to claim 3, characterized in that, Calculate the enthalpy of geothermal fluids using the following formula: In the formula, This indicates the predicted wellhead temperature. Indicates the specific enthalpy of saturated water. Indicates the latent heat of vaporization. Indicates the dryness of steam.

5. The frequency regulation method for a geothermal unit according to claim 4, characterized in that, The maximum frequency modulation capacity includes the maximum up-frequency modulation capacity and the maximum down-frequency modulation capacity; The maximum up-modulation capacity is calculated according to the following formula: In the formula, η is the unit's heat-to-work conversion efficiency. The predicted enthalpy of the geothermal fluid at the wellhead. The predicted wellhead fluid flow rate is determined by the pressure gradient within the wellbore calculated based on a two-phase flow model. The lower limit of the fluid enthalpy required to maintain minimum stable operation of the unit. The minimum fluid mass flow rate required to maintain stable operation of the unit. For safety margin coefficient, This is the maximum capacity limit that can be increased. The maximum down-regulation capacity is determined based on one or more of the following constraints: the lower limit flow rate constraint for safe operation of geothermal wellhead anti-scaling, the lower limit exhaust pressure constraint for safe operation of turbine, and the lower limit speed constraint for safe operation of working fluid pump. The lower limit flow rate constraint for safe operation of geothermal wellhead anti-scaling is determined based on the product of the predicted enthalpy of geothermal fluid and the lower limit flow rate for safe operation of anti-scaling.

6. The frequency regulation method for a geothermal unit according to claim 5, characterized in that, The adaptive automatic power generation control mode includes: The relationship between the unit's frequency regulation capability index and equipment safety constraints is determined in real time, and the determination result is obtained. The unit's frequency regulation capability index includes the maximum frequency regulation capacity, ramp rate, and regulation accuracy index. Based on the judgment result, it will automatically switch to one of the following modes: full-function participation mode, limited-amplitude participation mode, send-only-no-adjustment mode, or exit AGC mode. The current mode identifier is sent to the scheduling system, and the control strategy under the corresponding mode is executed.

7. The frequency regulation method for a geothermal unit according to claim 6, characterized in that, Based on the judgment result, it automatically switches to one of the following modes: full-function participation mode, limited participation mode, send-only-no-adjustment mode, or exits AGC mode, including: The equipment safety constraints include a first threshold characterizing the upper limit of the maximum up-frequency modulation capacity, a second threshold characterizing the upper limit of the maximum down-frequency modulation capacity, a third threshold characterizing the upper limit of the ramp rate, and a fourth threshold characterizing the upper limit of the ramp rate adjustment accuracy. When the maximum up-frequency modulation capacity is greater than or equal to the first threshold, the maximum down-frequency modulation capacity is greater than or equal to the second threshold, the ramp rate is greater than or equal to the third threshold, and the adjustment accuracy is less than or equal to the fourth threshold, switch to full-function participation mode. When any of the following indicators—maximum up-frequency modulation capacity, maximum down-frequency modulation capacity, ramp rate, or adjustment accuracy—is lower than the corresponding threshold but higher than the corresponding lower limit, switch to amplitude limiting participation mode. When the maximum up-modulation capacity or the maximum down-modulation capacity is lower than the corresponding lower limit, switch to transmit-only mode; When wellhead parameters drop suddenly or the turbine trips, switch to exit AGC mode.

8. A frequency regulation system for a geothermal unit, characterized in that, include: The data acquisition module is used to collect temperature, pressure, and flow parameters at the geothermal wellhead in real time. And predict the thermal fluid characteristics of the inland area in the near future using a multiphysics coupling model; The frequency regulation capability assessment module is used to calculate the maximum frequency regulation capacity, ramp rate, and regulation accuracy of the geothermal unit under current and predicted operating conditions based on the predicted geothermal fluid characteristic values. The parameter adjustment module is used to adaptively switch on and off automatic power generation control modes based on the maximum frequency regulation capacity, ramp rate, regulation accuracy index, and equipment safety constraints of the geothermal unit under current and predicted operating conditions.

9. An electronic device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that, When the processor executes the program, it implements the steps of the frequency regulation method for the geothermal unit as described in any one of claims 1 to 7.

10. A storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by the processor, it implements the steps of the frequency regulation method for the geothermal unit as described in any one of claims 1 to 7.

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