Geothermal heating and power generation combined system

Abstract

The invention relates to the technical field of geothermal heating, in particular to a geothermal heating and power generation combined system which comprises a geothermal heating end. A heating user and a generator set end; the heating and power generation combined unit is used for providing a small flow of heating medium water in a non-heating season and a large flow of heating medium water in a heating season to meet heat energy required by a generator set and heating users, and the pressure and the temperature in a heating pipeline are stable during heating, so that normal heating is realized; the heating and power generation combined unit comprises a plurality of heat exchangers connected in series, an intelligent adjusting valve and a temperature balance adjusting unit. The input ends of the heat exchangers connected in series are connected with a geothermal heat supply end, the output ends of the heat exchangers connected in series are connected with a heating user and a generator set end through a heat supply pipeline and a pump, and the heat supply pipeline is provided with an intelligent adjusting valve, a flow meter and a pressure transmitter. The requirements for small flow of the heating medium water in the non-heating season and large flow of the heating medium water in the heating season are met, and meanwhile, the pressure and the temperature in the heating pipeline are stable during heating, so that normal heating is achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of geothermal heating, and specifically relates to a combined geothermal heating and power generation system. Background Art

[0002] Geothermal energy is a clean, low-carbon and widely distributed renewable energy source with high utilization value. The utilization methods of geothermal energy are mainly divided into two types: co-utilization and upgrading utilization. Co-utilization includes district heating, pipeline tracing, etc., while upgrading utilization includes power generation, refrigeration, seawater desalination, etc. District heating can effectively reduce the installation of heating boilers in the area, reduce the consumption of coal and natural gas, thereby saving energy and reducing environmental pressure.

[0003] However, the existing geothermal heating systems have the following problems:

[0004] Waste of heat energy in non-heating seasons: In non-heating seasons, the heat medium water is cooled by a cooler, increasing the cooling cost and wasting heat energy resources;

[0005] The unstable temperature in the heating pipeline during the heating season affects the normal heating of users;

[0006] Low power generation efficiency: For heat medium water with a temperature between 50°C and 70°C, the economy of power generation is poor, and it is difficult to effectively utilize geothermal energy for power generation.

[0007] There is a need to design a combined geothermal heating and power generation system to improve the above problems. Summary of the Invention

[0008] The purpose of the present invention is to overcome the defects of the prior art and provide a combined geothermal heating and power generation system.

[0009] The present invention provides a combined geothermal heating and power generation system, including a geothermal heating end;

[0010] Heating users and a generator set end;

[0011] A heating and power generation combined unit for providing a small flow rate of heat medium water in non-heating seasons and a large flow rate of heat medium water in heating seasons to meet the heat energy required by the generator set and heating users, and at the same time stabilizing the pressure and temperature in the heating pipeline during heating to achieve normal heating;

[0012] The heating and power generation combined unit includes a plurality of serially connected heat exchangers, intelligent regulating valves and a temperature balance regulating unit;

[0013] The temperature balance regulating unit is used to make the heat exchange process between the geothermal heating end and the heating user end proceed smoothly;

[0014] The input ends of several series-connected heat exchangers are connected to the geothermal heating end, and the output ends of the several series-connected heat exchangers are connected to the heating users and the generator set end through a heat supply pipeline via a pump. An intelligent regulating valve, a flow meter, and a pressure transmitter are installed on the heat supply pipeline. The control device is respectively connected to the intelligent regulating valve, the flow meter, and the pressure transmitter through signal lines, and the control device adopts cascade dual-loop closed-loop control for jointly controlling the pressure and flow in the heat supply pipeline, converting the pressure difference between the heat supply end and the heat extraction end of the heat supply pipeline into a corresponding flow value to control the opening degree of the intelligent regulating valve, and realizing the switching between the small flow of the heat medium water in the non-heating season and the large flow of the heat medium water in the heating season.

[0015] Further, the control device includes a main control unit and a secondary control unit;

[0016] The main control unit consists of a main controller and a pressure-flow conversion module, and the secondary control unit consists of a secondary controller and a limiting module; the main control unit and the pressure transmitter form a main loop, and the secondary control unit, the intelligent regulating valve, and the flow meter form a secondary loop;

[0017] The main controller is used to receive the pressure value after the intelligent regulating valve collected by the pressure transmitter, compare it with the pressure set value to obtain a pressure difference, and output the pressure difference to the pressure-flow conversion module;

[0018] The pressure-flow conversion module is used to receive the pressure difference output from the main controller, convert the pressure difference into a corresponding flow value and output it to the secondary controller as the flow set value of the secondary loop;

[0019] The secondary controller is used to receive the flow value of the heat supply pipeline collected by the flow meter, compare it with the flow set value output from the pressure-flow conversion module, calculate the flow output value and output it to the limiting module;

[0020] The limiting module is used to receive the flow output value output from the secondary controller, perform limiting processing on it and then output it to the intelligent regulating valve to control the opening degree of the intelligent regulating valve.

[0021] Further, the main controller is a reverse-acting position-type PID controller.

[0022] Further, the intelligent regulating valve is an automatic flow regulating valve, and the secondary controller is a proportional-integral controller.

[0023] Further, the intelligent regulating valve is close to the heat medium water inlet end of the heat supply pipeline, the flow meter is close to the heat medium water outlet end of the heat supply pipeline, and the pressure transmitter is installed on the heat supply pipeline and communicated with the heat medium water outlet end of the heat supply pipeline.

[0024] Furthermore, the geothermal heating end includes a production well and a reinjection well. The production well is used for extracting heat from geothermal energy storage, and the reinjection well is used for reinjecting the heat energy after heat exchange.

[0025] The input ends of a number of serially connected heat exchangers are connected to the production well to meet the demand for a large flow rate of heat medium water during the heating season.

[0026] Furthermore, an evaporation heater is installed near the heat medium water outlet end of the heating pipeline to meet the heat energy requirements of the generator set and heating users.

[0027] Furthermore, the temperature balance adjustment unit includes:

[0028] A time controller for providing timing information to ensure the synchronous operation of the entire system and adapting to the temperature requirements at different time periods;

[0029] An input unit for inputting a temperature preset value;

[0030] A temperature measurement unit for real-time detection of the temperature at the heating user end and using the temperature at the heating user end as a temperature feedback value;

[0031] A judgment unit for analyzing and judging based on the temperature feedback value and the temperature preset value at the current moment. When the temperature feedback value at the current moment is greater than the temperature preset value, the temperature feedback value at the current moment is output;

[0032] An output unit for adjusting the power output at the corresponding temperature according to the temperature feedback value at the current moment. The power output at the corresponding temperature refers to the heat exchange efficiency of the heat exchanger and the opening degree of the intelligent regulating valve 7;

[0033] Among them, the time controller issues timing information, the temperature measurement unit detects the temperature at the heating user end in real time according to a preset frequency, and the judgment unit makes a judgment based on the temperature feedback value and the temperature preset value at the current moment, thereby realizing temperature control;

[0034] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0035] The geothermal heating and power generation combined system of the present invention includes a heating and power generation combined unit. The heating and power generation combined unit includes a number of serially connected heat exchangers, an intelligent regulating valve, and a temperature balance adjustment unit. The opening degree of the intelligent regulating valve on the heating pipeline is controlled by using a cascade double-loop closed-loop combined with the temperature balance adjustment unit, realizing the switching between a small flow rate of heat medium water in the non-heating season and a large flow rate of heat medium water in the heating season, and at the same time ensuring the stability of the pressure and temperature in the heating pipeline during heating to achieve normal heating at the user end. Description of the Drawings

[0036] The following drawings are only schematic illustrations and explanations of the present invention, and are not used to limit the scope of the present invention, where:

[0037] Figure 1 : Schematic diagram of the geothermal heating and power generation combined system of the present invention;

[0038] Figure 2 : Connection diagram of the geothermal heating and power generation combined system of the present invention;

[0039] Figure 3 : Overall control block diagram of the heating and power generation combined unit of the present invention;

[0040] In the figure: 1 - production well, 2 - reinjection well, 3 - heat supply pipeline, 4 - pressure transmitter, 5 - inlet end of heat transfer medium water, 6 - outlet end of heat transfer medium water, 7 - intelligent regulating valve, 8 - flowmeter, 9 - steam heater, 10 - pump, 11 - control device, 12 - heat exchanger, 13 - main controller, 14 - pressure - flow conversion module, 15 - sub - controller, 16 - amplitude - limiting module. Detailed implementation manners

[0041] In order to make the purpose, technical solutions, design methods and advantages of the present invention clearer and more understandable, the present invention will be further described in detail below through specific embodiments with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0042] As Figures 1 - 3 shown, the present invention provides a geothermal heating and power generation combined system, including a geothermal heating end;

[0043] heating users and a generator set end;

[0044] a heating and power generation combined unit for providing a small flow rate of heat transfer medium water in the non - heating season and a large flow rate of heat transfer medium water in the heating season to meet the power generation needs of the generator set and the heating needs of heating users;

[0045] The heating and power generation combined unit includes a plurality of heat exchangers 12, intelligent regulating valves 7 and a temperature equalization regulating unit connected in series;

[0046] a temperature equalization regulating unit for enabling the heat exchange process between the geothermal heating end and the heating user end to proceed smoothly;

[0047] Among them, the temperature equalization regulating unit includes:

[0048] a time controller for providing timing information to ensure the synchronous operation of the entire system and adapting to the temperature requirements in different time periods;

[0049] an input unit for inputting a temperature preset value;

[0050] A temperature measurement unit, which is used to detect the temperature of the heating user end in real time and use the temperature of the heating user end as a temperature feedback value;

[0051] A judgment unit, which is used to analyze and judge according to the temperature feedback value and the temperature preset value at the current moment. When the temperature feedback value at the current moment is greater than the temperature preset value, the temperature feedback value at the current moment is output;

[0052] An output unit, which is used to adjust the power output of the corresponding temperature according to the temperature feedback value at the current moment. The power output of the corresponding temperature refers to the heat exchange efficiency of the heat exchanger and the opening degree of the intelligent regulating valve 7;

[0053] Among them, the time controller issues timing information, the temperature measurement unit detects the temperature of the heating user end in real time according to a preset frequency, and the judgment unit makes a judgment according to the temperature feedback value and the temperature preset value at the current moment, so as to realize temperature control;

[0054] The input ends of a number of serially connected heat exchangers 12 are connected to the geothermal heating end. The output ends of a number of serially connected heat exchangers 12 are connected to the heating users and the generator set end through a heating pipeline 3 via a pump 10. The heating pipeline 3 is equipped with an intelligent regulating valve 7, a flow meter 8 and a pressure transmitter 4. The control device 11 is respectively connected to the intelligent regulating valve 7, the flow meter 8 and the pressure transmitter 4 through signal lines, and the control device 11 adopts a cascade double-loop closed-loop control to jointly control the pressure and flow in the heating pipeline, and converts the pressure difference between the heating end and the heat extraction end of the heating pipeline 3 into a corresponding flow value to control the opening degree of the intelligent regulating valve 7, so as to realize the switching between the small flow of the heat medium water in the non-heating season and the large flow of the heat medium water in the heating season;

[0055] It should be noted that the heating and power generation combined unit is used to provide the small flow of the heat medium water in the non-heating season and the large flow of the heat medium water in the heating season to meet the heat energy required by the generator set and heating users. At the same time, when heating, the pressure and temperature in the heating pipeline are stabilized to realize normal heating; among them, a number of serially connected heat exchangers 12 are used to meet the demand for the large flow of the heat medium water in the heating season. The control device 11 adopts a cascade double-loop closed-loop control to convert the pressure difference between the heating end and the heat extraction end into a corresponding flow value to better control the pressure of the heating pipeline, so that the pressure in the heating pipeline is stable; This application adopts a cascade double-loop closed-loop combined with a temperature equalization adjustment unit to control the opening degree of the intelligent regulating valve 7 on the heating pipeline, realizes the switching between the small flow of the heat medium water in the non-heating season and the large flow of the heat medium water in the heating season, and at the same time, when heating, the pressure and temperature in the heating pipeline are stabilized to realize normal heating;

[0056] Further, the intelligent regulating valve 7 is close to the hot medium water inlet end 5 of the heating pipeline 3, the flowmeter 8 is close to the hot medium water outlet end 6 of the heating pipeline 3, and the pressure transmitter 4 is installed on the heating pipeline 3 and communicated with the hot medium water outlet end 6 of the heating pipeline 3;

[0057] Further, the geothermal heating end includes a production well 1 and a reinjection well 2. The production well 1 is used for geothermal energy storage and heat extraction, and the reinjection well 2 is used for heat reinjection after heat exchange;

[0058] The input ends of a number of series-connected heat exchangers 12 are connected to the production well 1 to meet the demand for a large flow rate of hot medium water during the heating season;

[0059] Further, an evaporation heater 9 is installed at the hot medium water outlet end 6 of the heating pipeline 3 to meet the heat energy requirements of the generator set and heating users;

[0060] It should be noted that when the heat absorbed by the hot medium water after flowing through the heat exchanger 12 cannot meet the requirements of the generator set and heating users, the steam heater 9 with saturated steam with a heating medium of 1.0 MPa can be used to heat the hot medium water. Since the temperature range of the hot medium water required for residential heating is generally 50°C - 70°C, and when the return water temperature is too low, the power generation efficiency will be affected. Generally, the temperature of the hot medium water supplied to the generator set needs to be higher than 90°C. Therefore, to meet the specific requirements of residential heating and the generator set, a temperature control switch is also provided on the steam heater 9. During the heating season, when the return water temperature of the hot medium water monitored by the temperature control switch is lower than 50°C, the above-mentioned steam heater 9 is turned on. During the non-heating season, when the return water temperature of the hot medium water monitored by the temperature control switch is lower than 90°C, the above-mentioned steam heater 9 is turned on.

[0061] In addition, it should be noted that the geothermal energy mentioned in this system mainly refers to the temperature range generally between 70°C - 120°C. When designing the specific connection form of the geothermal energy heating and power generation combined system, the parameter information of the geothermal energy resources and the range of heating users are generally combined so that during the heating season, the feed water temperature of the hot medium water is controlled at 50°C - 70°C, and the return water temperature is controlled at 40°C - 50°C. During the non-heating season, the feed water temperature of the hot medium water is controlled at 90°C - 120°C, and the return water temperature is controlled at 70°C - 90°C, so that the entire system can operate stably and continuously, and at the same time meet the requirements of power generation efficiency and user heating.

[0062] Further, the control device 11 includes a main control unit and a sub-control unit;

[0063] The main control unit consists of a main controller 13 and a pressure-flow conversion module 14, and the secondary control unit consists of a secondary controller 15 and a limiting module 16; the main control unit and the pressure transmitter 4 form a main loop, and the secondary control unit, the intelligent control valve 7 and the flowmeter 6 form a secondary loop;

[0064] The main controller 13 is used to receive the pressure value after the intelligent control valve 7 collected by the pressure transmitter 4, compare it with the pressure set value to obtain a pressure difference, and output the pressure difference to the pressure-flow conversion module 14;

[0065] The pressure-flow conversion module 14 is used to receive the pressure difference output from the main controller 13, convert the pressure difference into a corresponding flow value and output it to the secondary controller 15 as the flow set value of the secondary loop;

[0066] The secondary controller 15 is used to receive the flow value of the heating pipeline 3 collected by the flowmeter 6, compare it with the flow set value output from the pressure-flow conversion module 14, calculate the flow output value and output it to the limiting module 16;

[0067] The limiting module 16 is used to receive the flow output value output from the secondary controller 15, perform a limiting process on it and then output it to the intelligent control valve 7 to control the opening degree of the intelligent control valve 7.

[0068] Among them, the limiting link in the limiting module 16 of the present invention is characterized in that when it detects that the flow reaches the threshold value, instead of keeping the opening degree of the intelligent control valve 7 unchanged, it changes the parameters of the secondary controller 16 to make the intelligent control valve 7 act in the opposite direction, so that it can not only avoid the flow exceeding the threshold value, but also enable the system to reach stability faster; therefore, the limiting module 16 can ensure that the pipeline flow will not be too small or too large regardless of how the control valve acts;

[0069] It should be noted that as Figure 1 shown, in the figure, Q_in is the flow rate of the heating medium water at the inlet of the intelligent control valve 7, Q_out is the flow rate of the heating medium water at the outlet of the intelligent control valve 7, and P1, P2, and P3 are the pressures of the heating medium water before the intelligent control valve 7, after the intelligent control valve 7, and at the detection point of the pressure transmitter 4 respectively. In the present invention, the pressure-flow conversion module is used to obtain the relationship between the pressure difference output by the main controller 13 and the flow set value of the secondary loop. When in use, for the pressure difference output by the main controller 13, through the pressure difference and flow calculation formula: flow Q = P / ρg, where P represents the pressure difference of the flowing medium, ρ represents the density of the flowing medium, and g represents the acceleration due to gravity, the flow set value of the secondary loop can be obtained;

[0070] The main controlled object of the present invention is the pressure of the heating medium water after the intelligent regulating valve 7. The secondary loop is to more timely and accurately control the pipeline pressure by controlling the flow rate to obtain a better control effect. Therefore, the pressure-flow conversion module is a model that converts pressure into flow rate, and can obtain the corresponding relationship between the system pressure and the flow rate according to the characteristics of the intelligent regulating valve 7 and the heating pipeline;

[0071] Further, the main controller 13 is a reverse-acting position type PID controller;

[0072] Main controller 13: Adopts a reverse-acting position type PID controller, which is used to receive the pressure value after the intelligent regulating valve 7 collected by the pressure transmitter 4, compare it with the pressure set value to obtain a pressure difference, and output the pressure difference to the pressure-flow conversion module 14;

[0073] Pressure-flow conversion module 14: It is used to receive the pressure difference output from the main controller 13, convert the pressure difference into a corresponding flow rate value and output it to the secondary controller as the flow rate set value of the secondary loop; in the present invention, the pressure difference output by the main controller 13 cannot be directly used as the flow rate set value for the flow rate control of the secondary loop. It is necessary to add a pressure-flow conversion module 13 to convert the pressure difference into a corresponding flow rate value. The value after being converted by the pressure-flow conversion module 14 is output to the secondary loop as the flow rate set value of the secondary loop;

[0074] Further, the intelligent regulating valve 7 is an automatic flow regulating valve, and the secondary controller 15 is a proportional-integral controller, which is used to accurately control the input and output of the liquid flow rate;

[0075] Working principle: During the heating season, the heating and power generation combined unit provides a large flow rate of heating medium water to meet the heat energy requirements of heating users and the generator set. The control device makes the temperature in the heating pipeline stable through cascade dual-loop closed-loop control and the temperature equalization adjustment unit to meet the demand for stable heating at the user end.

[0076] During the non-heating season, the heating and power generation combined unit provides a small flow rate of heating medium water to meet the requirements of the generator set. The control device ensures the stability of the flow rate and pressure of the heating medium water by controlling the opening of the intelligent regulating valve 7 to avoid waste of heat energy.

[0077] It should be noted that the combined heating and power generation unit provided in the geothermal heating and power generation combined system of the present invention includes an intelligent regulating valve 7. The control device 11 is respectively connected to the intelligent regulating valve 7, the flowmeter 8, and the pressure transmitter 4 through signal lines. The control device 11 adopts a cascade dual-loop closed-loop control method to convert the pressure difference between the heat supply end and the heat extraction end into a corresponding flow value to better control the pressure of the heating pipeline, and jointly control the pressure and flow in the heat supply pipeline. The main loop in the control device 11 collects the pressure value after the intelligent regulating valve 7 through the pressure transmitter 4. The main controlled object is the heat medium water pressure after the intelligent regulating valve 7. When the flow of the heat medium water in the heat supply pipeline changes, in order to keep the heat medium water pressure after the intelligent regulating valve 7 stable near the set value, the flow is controlled through the secondary loop in the control device 11 to more timely and accurately control the pipeline pressure, obtaining a better control effect. Thus, during heating, the pressure of the heat medium water entering the heating user end in the heat supply pipeline is stable near the set value, realizing normal heating;

[0078] The relationship between the pressure difference output by the main controller 13 and the flow set value of the secondary loop is obtained through the pressure-flow conversion module. When in use, for the pressure difference output by the main controller 13, the flow set value of the secondary loop can be obtained through the pressure-difference and flow calculation formula. The secondary loop is to more timely and accurately control the pipeline pressure through the control of the flow, obtaining a better control effect. The main controlled object in this application is the heat medium water pressure after the intelligent regulating valve 7. The pressure-flow conversion module is a model that converts pressure into flow, and obtains the corresponding relationship between the system pressure and flow according to the characteristics of the intelligent regulating valve 7 and the heat supply pipeline; the pressure difference output by the main controller 13 is converted into a corresponding flow value to control the opening of the intelligent regulating valve 7, realizing the switching between large flow and small flow of the heat medium water in the heating season and non-heating season.

[0079] In the above, a main-secondary loop transfer function is set in the control device to construct the coupling relationship and control relationship between the main loop and the secondary loop, and an accurate pressure-flow conversion model is established based on the fluid mechanics equation. The coupling relationship and control relationship between the main loop and the secondary loop are written into the main controller 13 in the form of logical control, and the main controller 13 and the pressure-flow conversion model are coupled, where the pressure-flow conversion model is set in the pressure-flow conversion module.

[0080] In the above, main loop (pressure control): P(s) = G_p(s)·V(s) + D_p(s), where: G_p(s) = K_p / (τ_p s + 1) (pressure transfer function);

[0081] D_p(s): pipeline disturbance term;

[0082] Secondary loop (flow control):

[0083] Q(s) = G_q(s)·u(s);

[0084] G_q(s)=K_q e^{-T_d s} / (τ_q s+1)(flow-valve opening transfer function)

[0085] The above symbols have the following meanings:

[0086]

[0087]

[0088] In the heating and power generation combined unit, a target heat medium water flow demand level is generated according to the real-time seasonal (heating season / non-heating season) demand model, and a pressure-flow cascade dual-circuit closed-loop control mode is set according to the target heat medium water flow demand level. A large flow mode is set in the heating season to simultaneously meet the basic load of the generator set and the peak heat demand of the heating users. A small flow mode is set in the non-heating season to maintain only the minimum heat medium water circulation volume of the generator set to prevent the pipe from freezing.

[0089] During the heat exchange process, the temperature balance adjustment unit performs the following operations: collect the heat medium water temperature (T_out) at the heat exchanger outlet and the feedback temperature (T_user) at the heating user end; if |T_out-T_user|>threshold, the heat compensation allocation strategy between the multi-stage heat exchangers is triggered: adjust the diversion ratio of the series heat exchanger, or inject buffer medium to smooth temperature fluctuations; adjust the opening of the intelligent regulating valve in linkage to compensate for the impact of fluid viscosity differences caused by temperature changes on flow control. Automatically switch between large / small flow modes according to the preset schedule or ambient temperature sensor signal, and use a ramp function to smoothly transition the flow setting value during the switching process to avoid water hammer effect.

[0090] In the above, the pressure-flow conversion model is constructed based on the following method: based on the pipeline fluid mechanics equation (modified form of Bernoulli equation), an accurate conversion relationship between ΔP and Q is established.

[0091]

[0092] Among them, ρ is the density of heat medium water, A is the cross-sectional area of ​​the pipe, f is the friction coefficient, L / D is the aspect ratio of the pipe, g is the gravitational acceleration, and h is the elevation difference.

[0093] The above equation is discretized and written into the pressure-flow conversion module, real-time sensor data (temperature, density, pipeline parameters) is input, and the mapping relationship between ΔP and Q is output; the main controller 13 calls this module to dynamically correct the main loop transfer function parameters to eliminate the influence of fluid property changes on control accuracy.

[0094] In the above, control logic implementation and dynamic optimization include:

[0095] Calibrate the initial parameters of the transfer function through a step response experiment, and use the genetic algorithm to optimize the parameters of the main-secondary loop controller, so that the overshoot of the system response is <5%, and the steady-state time is <30 s. When it is detected that the change in the temperature of the heating medium water exceeds ±5°C or the density fluctuation exceeds ±3%, trigger the recalculation of the pressure-flow conversion model and update the transfer function of the main loop; the secondary loop adopts a fuzzy PID algorithm to dynamically adjust the secondary loop according to the flow deviation to form an adaptive regulation.

[0096] Through the deep integration of the dynamic coupling of the main-secondary loop and the hydrodynamic model, this application realizes the precise decoupling and collaborative optimization of the pressure-flow control of the geothermal system, significantly improves the control stability and energy efficiency under variable working conditions, and is especially suitable for the high-dynamic management requirements of the heating medium water in the combined geothermal heating and power generation system.

[0097] This application realizes the dynamic regulation of the pressure and flow of the heating medium water through the following steps:

[0098] Step S1: Construct a cascade pressure-flow cascade dual-loop closed-loop control mode:

[0099] (1.1) Establish a cascade architecture of the main pressure control loop and the secondary flow control loop;

[0100] (1.2) Set the pressure at the rear end of the intelligent regulating valve as the controlled parameter for the main loop;

[0101] (1.3) Configure the secondary loop with the real-time flow rate of the heating medium water as the adjustment parameter;

[0102] (1.4) Realize the data interaction of the dual-loop through the signal transmission channel;

[0103] Step S2: Model the dynamic conversion of pressure-flow:

[0104] (2.1) Establish a differential pressure-flow conversion equation based on the hydrodynamic characteristics of the pipeline;

[0105] (2.2) Develop a conversion algorithm adaptable to multi-condition parameters;

[0106] (2.3) Set the switching threshold of the seasonal mode:

[0107] Heating season mode: Q ≥ Q_max (large flow rate condition);

[0108] Non-heating season mode: Q ≤ Q_min (small flow rate condition).

[0109] Step S3: Execute the cascade closed-loop control:

[0110] (3.1) The main controller receives the real-time monitoring data of the pressure transmitter;

[0111] (3.2) Calculate the dynamic deviation ΔP between the actual pressure and the set value;

[0112] (3.3) Generate the set value Q_set of the secondary loop flow rate through the conversion model;

[0113] (3.4) The secondary controller performs PID operation on the measured value of the flowmeter;

[0114] (3.5) Output the adjustment signal to the intelligent control valve actuator

[0115] Step S4: Dynamic parameter optimization:

[0116] (4.1) Establish a pressure volatility feedback mechanism: δ = ΔP_max / P_set × 100%;

[0117] (4.2) Set the double-threshold adjustment interval:

[0118] When the warning threshold δ ≥ 5%, trigger parameter recalibration

[0119] When the safety threshold δ ≥ 10%, start the emergency adjustment mode;

[0120] (4.3) Implement the valve characteristic self-learning algorithm: Update K = f(valve opening, medium temperature, pipe resistance characteristic) in real time.

[0121] Through the differential pressure-flow conversion model, realize the decoupling control of two parameters, adopt the feedforward-feedback composite regulation strategy, shorten the system response time by 40%, reduce the pressure fluctuation amplitude to within ±2.5%, and significantly improve the operation stability of the geothermal system under different load conditions.

[0122] The embodiments of the present invention have been described above. The above description is exemplary, not exhaustive, and is not limited to the disclosed embodiments. Many modifications and variations are obvious to those of ordinary skill in the art in the technical field without departing from the scope and spirit of the described embodiments. The selection of the terms used herein is intended to best explain the principles of the embodiments, the practical application, or the improvement of the technology in the market, or to enable other ordinary technical personnel in the technical field to understand the disclosed embodiments.

Claims

1. A geothermal heating and power generation combined system, characterized in that: Including geothermal heating end; Geothermal heating end; Heating users and generator sets; The heating and power generation combined unit is used to provide a small flow of heat medium water in the non-heating season and a large flow of heat medium water in the heating season to meet the heat energy required by the generator set and heating users, and at the same time stabilize the pressure and temperature in the heating pipeline to achieve normal heating during heating; The heating and power generation combined unit includes a plurality of heat exchangers, an intelligent regulating valve and a temperature balancing regulating unit connected in series; The temperature balance adjustment unit is used to ensure that the heat exchange between the geothermal heating end and the heating user end proceeds smoothly; The input ends of several series-connected heat exchangers are connected to the geothermal heating end, and the output ends of several series-connected heat exchangers are connected to the heating user and the generator set end through a heating pipeline via a machine pump. The heating pipeline is installed with an intelligent regulating valve, a flow meter and a pressure transmitter. The control device is respectively connected to the intelligent regulating valve, the flow meter and the pressure transmitter through signal lines, and the control device adopts a cascade double-circuit closed-loop control for jointly controlling the pressure and flow in the heating pipeline, converting the pressure difference between the heating end and the heat extraction end of the heating pipeline into a corresponding flow value to control the opening of the intelligent regulating valve, thereby realizing the switching between a small flow of heat medium water in the non-heating season and a large flow of heat medium water in the heating season.

2. A geothermal heating and power generation combined system according to claim 1, characterized in that: The control device comprises a main control unit and a sub-control unit; The main control unit is composed of a main controller and a pressure-flow conversion module, and the sub-control unit is composed of a sub-controller and a limiting module; the main control unit and the pressure transmitter constitute a main loop, and the sub-control unit, the intelligent regulating valve and the flow meter constitute a sub-loop; The main controller is used to receive the pressure value after the intelligent regulating valve collected by the pressure transmitter, compare it with the pressure setting value to obtain a pressure difference, and output the pressure difference to the pressure-flow conversion module; The pressure-flow conversion module is used to receive the pressure difference value outputted from the main controller, convert the pressure difference value into a corresponding flow value and output it to the sub-controller as a flow setting value of the sub-circuit; The sub-controller is used to receive the flow value of the heating pipeline collected by the flow meter, and compare it with the flow setting value output from the pressure flow conversion module, calculate and obtain the flow output value and output it to the limiting module; The limiting module is used to receive the flow output value from the sub-controller, perform limiting processing on it, and then output it to the intelligent regulating valve to control the opening of the intelligent regulating valve.

3. A geothermal heating and power generation combined system according to claim 2, characterized in that: The main controller is a reaction position PID controller.

4. A geothermal heating and power generation combined system according to claim 1 or 2, characterized in that: The intelligent regulating valve is an automatic flow regulating valve, and the sub-controller is a proportional-integral controller.

5. A geothermal heating and power generation combined system according to claim 1, characterized in that: The intelligent regulating valve is close to the heat medium water inlet end of the heating pipe, the flow meter is close to the heat medium water outlet end of the heating pipe, and the pressure transmitter is installed in the heating pipe and is connected to the heat medium water outlet end of the heating pipe.

6. A geothermal heating and power generation combined system according to claim 1, characterized in that: The geothermal heating end includes a production well and a reinjection well, wherein the production well is used for geothermal energy storage and heat extraction, and the reinjection well is used for reinjecting heat energy after heat exchange; The input ends of several series-connected heat exchangers are connected to production wells to meet the large flow demand of heat medium water during the heating season.

7. A geothermal heating and power generation combined system according to claim 5, characterized in that: An evaporative heater is installed near the outlet end of the heat medium water in the heating pipeline to meet the heat energy needs of the generator set and heating users.

8. A geothermal heating and power generation combined system according to claim 1, characterized in that: The temperature balance adjustment unit comprises: Time controller, used to provide timing information to ensure synchronous operation of the entire system and adapt to temperature requirements in different time periods; An input unit, used for inputting a preset temperature value; A temperature measuring unit, used to detect the temperature of the heating user end in real time and use the temperature of the heating user end as a temperature feedback value; A judgment unit, used for analyzing and judging according to the temperature feedback value at the current moment and the temperature preset value, and outputting the temperature feedback value at the current moment when the temperature feedback value at the current moment is greater than the temperature preset value; An output unit, used to adjust the power output of the corresponding temperature according to the temperature feedback value at the current moment, wherein the power output of the corresponding temperature refers to the heat exchange efficiency of the heat exchanger and the opening and closing degree of the intelligent regulating valve 7; Among them, the time controller sends out timing information, the temperature measuring unit detects the temperature of the heating user end in real time according to the preset frequency, and the judgment unit makes a judgment based on the temperature feedback value and the temperature preset value at the current moment, thereby realizing temperature control.

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