A tee valve step and variable frequency pump cooperative control system based on temperature difference change rate

Abstract

The application discloses a three-way valve stepping and variable frequency pump collaborative control system based on temperature difference change rate, and belongs to the thermal management technical field of wind power generation equipment. The three-way valve stepping and variable frequency pump collaborative control system comprises a pump station, a radiator, a heat generating device to be cooled and a control end. The heat generating device to be cooled is a component needing heat dissipation in a wind turbine generator unit. The pump station is communicated with the heat generating device through a water cooling loop, is used for realizing heat generating device cooling, and is communicated with the radiator through a built-in three-way valve for selecting, is used for completing medium temperature control in the water cooling loop, and the control end completes variable frequency water pump and three-way valve control in the pump station based on collected environmental temperature information, cooling loop monitoring parameters and a preset control algorithm, so as to complete heat generating device temperature control. Through the control system, environmental temperature information is effectively utilized, predictive regulation of cooling capacity is realized, and the response time of the system to environmental temperature mutation and unit power change is significantly shortened.

Description

Technical Field

[0001] This application belongs to the field of thermal management technology for wind power generation equipment, and particularly relates to a three-way valve stepper and variable frequency pump coordinated control system based on the rate of change of temperature difference. Background Technology

[0002] In current wind power environmental control water cooling systems, water pumps operate at a fixed speed using industrial frequency, and the heat dissipation capacity of the radiators is significantly affected by ambient temperature, easily leading to overcooling. Common countermeasures include controlling the flow direction using three-way valves and employing logic to start and stop the water pumps to control the system water temperature.

[0003] Using only start-stop logic will cause the water pump to be frequently subjected to the impact of starting and stopping, thus greatly reducing the life of the water pump;

[0004] When only the three-way valve is switched, the microswitch inside the three-way valve, which is used to provide feedback position signals, will be frequently switched on and off. This will accelerate the oxidation of its contact surface, leading to poor contact and resulting in the inability to receive signals and triggering an alarm.

[0005] When only the three-way valve is switched, the three-way valve will continuously open and close according to the logic control to adjust the opening degree of the three-way valve. Its internal transmission gear will rotate frequently in a certain small range. The gear in this range will wear out due to frequent rotation, which will cause the three-way valve to fail prematurely.

[0006] Simply switching the three-way valve may cause a sudden drop in temperature due to residual coolant in the radiator.

[0007] When only the three-way valve is switched, it is in a half-open state within a certain ambient temperature range (such as 20-30℃). In the half-open state, part of the system flow does not pass through the heat exchanger. The kinetic energy of this part of the flow is converted into heat in the system and lost, resulting in serious energy waste.

[0008] If the pump is operated solely by frequency converter, the pump frequency will be too low under low temperature conditions, which will lead to a serious lack of pump efficiency, making it unable to provide a stable flow rate or even causing it to stop working.

[0009] If the pump is operated by frequency converter only, the pump may deviate from the high-efficiency operating range, and the efficiency will be greatly reduced. In order to compensate for insufficient heat dissipation, the high-load operation time needs to be extended, and the total energy consumption will increase.

[0010] If the water pump is operated solely by frequency converter control, the temperature difference between the inlet and outlet of the heating element will increase, resulting in condensation due to excessively low inlet temperature.

[0011] Existing methods require constant temperature adjustments and monitoring, making it difficult to quickly adapt to changes in the unit's power generation.

[0012] In summary, existing wind power environmental control water cooling systems suffer from two major contradictions:

[0013] The inherent limitations of single-method approaches: relying solely on three-way valve regulation (leading to frequent operation, wear, and energy waste) or solely on water pump frequency conversion (resulting in insufficient low-temperature efficiency, condensation due to excessive temperature differences, and increased energy consumption when deviating from the high-efficiency zone) cannot achieve efficient, reliable, and long-life temperature control under all operating conditions (especially when there are drastic changes in ambient temperature and fluctuations in unit power). Simply combining the two methods (such as opening the valve first and then using frequency conversion) still cannot avoid the above problems and lacks synergistic optimization.

[0014] Lack of proactive adjustment: Existing control mainly relies on feedback from the outlet temperature (T_liquid) of the cooled equipment, and only uses the ambient temperature (T_ambient) as an auxiliary reference or does not make full use of it, which is a key disturbance source. This results in a lag in system response and difficulty in quickly adapting to sudden changes in the environment and changes in unit power.

[0015] The existing national standard for wind power cooling systems, GB / T 19960-2024 "General Technical Conditions and Test Methods for Wind Turbine Generator Sets in Wind Power Generation Systems," states in clause 5.1.7 that for rotating parts, electrical systems, or bearings within the unit that have specific requirements regarding operating temperature and ambient temperature, a more suitable cooling system should be configured to meet the temperature control requirements. The cooling medium can be air-cooled, water-cooled, or other cooling media. Cooling systems are divided into active cooling and passive cooling; the selection of components within an active cooling system should meet design requirements. For systems with cooling systems, the temperature of the cooling medium should be monitored, and the unit should have corresponding protection measures if the temperature is too high. The following are not covered: the gradual opening adjustment method for three-way valves; the control architecture using ambient temperature as a feedforward input; and the energy-saving and anti-freezing strategy of pump-valve coordination.

[0016] Therefore, there is an urgent need in this field for a control strategy that can overcome the shortcomings of the above-mentioned single means and make full use of T-ring information for forward-looking and collaborative optimization, so as to achieve adaptive, highly reliable, long-life and efficient operation of the cooling system under complex working conditions. Summary of the Invention

[0017] The purpose of this application is to overcome the problems of the prior art by disclosing a three-way valve stepper and variable frequency pump coordinated control system based on the rate of change of temperature difference. Through the setting of this control system, the ambient temperature information is effectively utilized to realize the predictive adjustment of cooling capacity and significantly shorten the system's response time to sudden changes in ambient temperature and unit power.

[0018] The objective of this application is achieved through the following technical solution:

[0019] A three-way valve stepper motor and variable frequency pump coordinated control system based on temperature difference change rate, the three-way valve stepper motor and variable frequency pump coordinated control system includes: pump station, radiator, heat-generating equipment to be cooled and control terminal; the heat-generating equipment to be cooled is the component in the wind turbine that needs heat dissipation;

[0020] The pump station is connected to the heating equipment through a water cooling circuit for cooling the heating equipment, and the pump station is connected to the radiator through an internal three-way valve to control the temperature of the medium in the water cooling circuit.

[0021] The control terminal controls the variable-frequency water pump and the three-way valve in the pump station based on the collected ambient temperature information, cooling circuit monitoring parameters, and a preset control algorithm to control the temperature of the heating equipment.

[0022] According to a preferred embodiment, the control terminal uses the following control algorithm to control the variable-frequency water pump and the three-way valve, including:

[0023] In the initial state, the three-way valve is switched to the internal circulation, that is, the water inlet end AB is responsible for water inlet, the water outlet end B is responsible for water outlet, the water outlet end A is shut off, and the variable-frequency water pump is controlled to operate at the lowest frequency, and the liquid temperature of the cooling water cooling circuit is detected.

[0024] If the medium T_liquid at the inlet end of the heating equipment in the cooling circuit ≤ 23°C, the heater is started until the medium temperature is greater than 23°C, and the wind turbine operates; if the liquid temperature T_liquid > 23°C, the wind turbine operates.

[0025] According to a preferred embodiment, the control algorithm further includes: initial heating and valve opening trigger.

[0026] When T_liquid > 25°C and T_liquid continues to rise, that is, when the liquid temperature change ΔT_liquid ≥ ΔT_threshold °C in each measurement cycle, the control terminal sends a valve opening pulse command to the actuator of the three-way valve, and opens the water outlet end A according to the pulse.

[0027] And the process of judging the liquid temperature and sending pulses is repeated until the water outlet end A of the three-way valve reaches the fully open state.

[0028] Among them, after the three-way valve actuator receives 15 pulses, the water outlet end A of the three-way valve reaches the fully open state, and the valve opening runs 6° for each pulse received by the actuator.

[0029] According to a preferred embodiment, the control algorithm further includes: collaborative control based on the real-time temperature difference ΔT(real) between the liquid temperature T_liquid and the ambient temperature T_env, including:

[0030] Based on the real-time temperature difference ΔT(real) and the designed temperature difference ΔT(designed), calculate the required frequency f_demand of the variable-frequency water pump to make ΔT(real) ≈ ΔT(designed) ± tolerance:

[0031] 1) When ΔT(real) < ΔT(designed), or T_liquid < T_set_low,

[0032] If the pump demand frequency f_demand ≤ f_min_safe, then set the pump frequency f = f_min_safe.

[0033] Simultaneously triggering the three-way valve closing logic judgment, including: if the liquid temperature (T_liquid) drops and the temperature drop is ≥ΔT_threshold ℃ within a preset period, send a valve closing pulse command to the three-way valve actuator, and repeat this judgment and pulse sending process until the outlet A of the three-way valve reaches the fully closed state or T_liquid ≤ 25℃. During the valve closing process, after the three-way valve actuator receives 15 pulses, the outlet A of the three-way valve reaches the fully closed state. For each pulse received by the actuator, the valve closing degree moves by 6°.

[0034] If the pump demand frequency f_demand > f_min_safe, set the pump frequency f = f_demand;

[0035] 2) When ΔT (real-time) > ΔT (design)

[0036] If the outlet A of the three-way valve is not fully open, the valve opening logic is triggered, and the outlet A of the three-way valve is opened by pressing the pulse until the outlet A of the three-way valve is fully open.

[0037] If the outlet A of the three-way valve is fully open, and ΔT (real-time) is still greater than ΔT (design) + tolerance, then the frequency f of the variable frequency pump is increased according to f_demand.

[0038] According to a preferred embodiment, the control algorithm further includes: an over-temperature alarm.

[0039] When ΔT (real-time) > ΔT (design), the frequency of the variable frequency water pump f >= 50Hz, the water end A of the three-way valve is fully open and the liquid temperature T continues to rise, an over-temperature alarm signal is output.

[0040] According to a preferred embodiment, the three-way valve includes an inlet end AB, an outlet end A, and an outlet end B, wherein the inlet end AB is connected to the pump station output pipe, the outlet end A is connected to the radiator inlet, the radiator outlet is connected to the heating device, and the outlet end B is connected to the heating device.

[0041] According to a preferred embodiment, the pumping station includes: a frequency converter, a frequency converter water pump, a first pressure sensor, a second pressure sensor, a first temperature sensor, and a second temperature sensor;

[0042] The second pressure sensor and the second temperature sensor are located upstream of the variable frequency water pump and downstream of the heating device; the first pressure sensor is located upstream of the downstream transmitting device of the variable frequency water pump; the first temperature sensor is located upstream of the downstream heating device of the radiator.

[0043] The frequency converter controls the variable frequency water pump based on the control terminal signal.

[0044] According to a preferred embodiment, the pumping station further includes a buffer tank, which is located upstream of the variable frequency pump.

[0045] According to a preferred embodiment, the pumping station further includes a flow meter disposed downstream of the variable frequency pump.

[0046] The aforementioned main solution and its various further alternative solutions can be freely combined to form multiple solutions, all of which are solutions that can be adopted and are claimed in this application. Those skilled in the art, after understanding the solution of this application, will realize that there are many combinations based on the prior art and common general knowledge, all of which are technical solutions to be protected in this application, and will not be exhaustively listed here.

[0047] The beneficial effects of this application are:

[0048] The "pulse command" mechanism: This application employs discrete, step-by-step pulse commands to control the three-way valve. Each pulse drives the actuator to rotate a fixed small angle (corresponding to a small distance movement of the valve core). This is significantly different from traditional analog continuous regulation or simple on / off control. Its advantages are: greatly reducing the frequent micro-oscillations of the three-way valve in the intermediate opening region (which is the main cause of local wear of gears and frequent on / off switching of microswitches). Valve position adjustment is only triggered when the accumulated temperature change reaches a certain threshold (ΔT_threshold), effectively filtering out small temperature fluctuation interference and greatly reducing the number of valve actions.

[0049] The core role of ambient temperature (T_loop): The T_loop is not only crucial for calculating the effective temperature difference ΔT (in real time), but more importantly, it serves as a feedforward signal. When the T_loop increases, the algorithm predicts a decrease in radiator efficiency and proactively increases the flow rate (by opening valves or increasing frequency); when the T_loop decreases, the algorithm predicts a risk of overcooling and proactively reduces the flow rate (by closing valves or decreasing frequency). This is key to achieving a fast response (approximately 30 seconds), overcoming the hysteresis (approximately 180 seconds) of traditional single feedback control.

[0050] Collaborative decision-making logic: Based on the magnitude and trend of the ΔT (real-time) deviation, the algorithm intelligently selects the most effective adjustment method (priority valve, priority pump, or a combination of both) and the adjustment range (fine step or large range), aiming to always push the system towards the stable state of the three-way valve fully open / fully closed and the efficient operating range of the pump. Attached Figure Description

[0051] Figure 1 This is a schematic diagram of the system structure of this application.

[0052] Among them, 1-buffer tank, 2-variable frequency water pump, 3-air vent valve, 4-pressure gauge, 51-first pressure sensor, 52-second pressure sensor, 61-first temperature sensor, 62-second temperature sensor, 7-flow meter, 8-three-way valve, 9-radiator. Detailed Implementation

[0053] The following specific examples illustrate the implementation of this application. Those skilled in the art can easily understand other advantages and effects of this application from the content disclosed in this specification. This application can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of this application. It should be noted that, unless otherwise specified, the following embodiments and features in the embodiments can be combined with each other.

[0054] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0055] In the description of this application, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product of this application is in use. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on this application. In addition, the terms "first," "second," and "third," etc., are only used to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0056] Furthermore, terms such as "horizontal," "vertical," and "sag" do not imply that components must be absolutely horizontal or suspended, but rather that they can be slightly tilted. For example, "horizontal" simply means that its direction is more horizontal relative to "vertical," and does not mean that the structure must be completely horizontal, but can be slightly tilted.

[0057] In the description of this application, it should also be noted that, unless otherwise expressly specified and limited, the terms "set up," "install," "connect," and "link" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0058] Furthermore, it should be noted that unless otherwise specified in this application, the specific structures, connections, positions, power sources, etc. involved are all things that a person skilled in the art can know without creative effort based on the prior art.

[0059] Example

[0060] refer to Figure 1 As shown, this application discloses a three-way valve stepper and variable frequency pump coordinated control system based on the rate of change of temperature difference.

[0061] The three-way valve stepper motor and variable frequency pump coordinated control system includes: pump station, radiator, heat-generating equipment to be cooled, and control terminal; the heat-generating equipment to be cooled is the component in the wind turbine that needs heat dissipation;

[0062] The pump station is connected to the heat-generating equipment via a water-cooling circuit to cool the equipment. The pump station also has a built-in three-way valve that selectively connects to a radiator to control the temperature of the medium in the water-cooling circuit.

[0063] The control terminal controls the variable frequency water pump and three-way valve in the pump station based on the collected ambient temperature information, cooling circuit monitoring parameters and preset control algorithms, so as to control the temperature of the heat-generating equipment.

[0064] Preferably, the three-way valve includes an inlet end AB, an outlet end A, and an outlet end B, wherein the inlet end AB is connected to the pump station output pipe, the outlet end A is connected to the radiator inlet, the radiator outlet is connected to the heating device, and the outlet end B is connected to the heating device.

[0065] In this embodiment, the pump station includes: a frequency converter, a frequency converter water pump, a first pressure sensor, a second pressure sensor, a first temperature sensor, and a second temperature sensor. The second pressure sensor and the second temperature sensor are located upstream of the frequency converter water pump and downstream of the heat-generating equipment, respectively. The first pressure sensor is located upstream of the heat-generating equipment downstream of the frequency converter water pump, and the first temperature sensor is located upstream of the heat-generating equipment downstream of the radiator. The frequency converter outputs three-phase AC power of a corresponding frequency based on the control terminal signal to complete the control of the frequency converter water pump. The first temperature sensor and the second temperature sensor are used to measure and detect the temperature of the medium in the water-cooling circuit, and the first pressure sensor and the second pressure sensor are used to monitor the pressure in the water-cooling circuit.

[0066] In this embodiment, the variable frequency water pump is typically a centrifugal pump or other pump suitable for variable frequency drive, driven by a frequency converter. Its rotational speed (N) is proportional to the output frequency (f) of the frequency converter (N ≈ k * f, k is a constant). Flow rate (Q_liquid) ∝ rotational speed (n), and correspondingly, flow rate (Q_liquid) ∝ frequency (f). Head (H) is proportional to the square of the rotational speed, H ∝ n. 2 ∝f 2 Power (P) is directly proportional to the cube of the rotational speed: P∝n 3 ∝f 3 .

[0067] Preferably, the core processing unit of the control terminal in this embodiment is a PLC, a dedicated control board, an industrial computer, etc., and has: analog / digital input interface: used to receive signals from the T_liquid and T_ring sensors; analog / digital output interface: used to send frequency control signals (such as 0-10V, 4-20mA, Modbus RTU, etc.) to the frequency converter; data processing and logic operation capabilities: to execute the core control algorithm; human-machine interface (HMI) (optional): used for parameter setting and status display; communication interface (optional): used to communicate with the wind turbine main control system, report status, and receive instructions.

[0068] Preferably, in this embodiment, the radiator is the core heat dissipation component of the water-cooled system (such as an air-cooled chiller or a liquid-liquid heat exchanger). Its heat dissipation power (P_dissipation) is related to factors such as the flow rate of the coolant flowing through it (Q_liquid), the airflow at the cold end of the radiator (Q_air), and the temperature difference between the coolant and the ambient air (ΔT = T_liquid - T_ambient). The flow rate Q_liquid is approximately proportional to the pump speed N (Q_liquid ≈ C * N, where C is a constant related to the pump and piping characteristics).

[0069] Preferably, the heat-generating device in this embodiment is the component in the wind power equipment that needs heat dissipation, such as the converter, generator bearing, gearbox oil cooler, etc.

[0070] Preferably, the pumping station further includes a buffer tank and a flow meter, wherein the buffer tank is located upstream of the variable frequency pump and the flow meter is located downstream of the variable frequency pump.

[0071] In this example, the control terminal uses the following control algorithm to control the variable frequency water pump and the three-way valve, including the following steps.

[0072] Step 1: In the initial state, the three-way valve switches to internal circulation, meaning the inlet AB is responsible for water intake, the outlet B is responsible for water output, the outlet A is closed, and the variable frequency water pump is controlled to operate at the lowest frequency to monitor the cooling water circuit liquid temperature.

[0073] If the medium temperature \(T_{liquid}\) at the inlet end of the heating device in the cooling circuit is less than or equal to \(23^{\circ}C\), start the heater until the medium temperature is greater than \(23^{\circ}C\), and the wind turbine operates; if the liquid temperature \(T_{liquid}>23^{\circ}C\), the wind turbine operates.

[0074] Step 2: Initial temperature rise and valve opening trigger.

[0075] When \(T_{liquid}>25^{\circ}C\) and \(T_{liquid}\) continues to rise, that is, when the liquid temperature change \(\Delta T_{liquid}\geq\Delta T_{threshold}\) °C in each measurement period, the control terminal sends an open valve pulse command to the actuator of the three-way valve 8, and opens the water outlet end A according to the pulse;

[0076] And repeat the process of judging the liquid temperature and sending the pulse until the water outlet end A of the three-way valve reaches the fully open state;

[0077] Among them, after the three-way valve actuator receives 15 pulses, the water outlet end A of the three-way valve reaches the fully open state. For each pulse received by the actuator, the valve opening runs \(6^{\circ}\).

[0078] Step 3: Perform coordinated control based on the real-time temperature difference \(\Delta T\) (real-time) between the liquid temperature \(T_{liquid}\) and the ambient temperature \(T_{ambient}\), including:

[0079] Based on the real-time temperature difference \(\Delta T\) (real-time) and the designed temperature difference \(\Delta T\) (designed), calculate the required frequency \(f_{demand}\) of the variable-frequency water pump to make \(\Delta T\) (real-time) \(\approx\Delta T\) (designed) \(\pm\) tolerance:

[0080] Case A: When \(\Delta T\) (real-time) < \(\Delta T\) (designed), or \(T_{liquid}<T_{set\_low}\)

[0081] If the required frequency \(f_{demand}\) of the water pump is less than or equal to \(f_{min\_safe}\), that is, lower than the safe speed, set the water pump frequency \(f = f_{min\_safe}\), that is: when the temperature decreases and the calculated water pump frequency is lower than the minimum frequency, the water pump operates at the minimum frequency at this time to ensure the stable operation of the pump.

[0082] At the same time, trigger the three-way valve closing logic judgment, including: if \(T_{liquid}\) drops and the dropped temperature is greater than or equal to \(\Delta T_{threshold}\) °C within the preset period, send a closing valve pulse command to the three-way valve actuator, and repeat this judgment and pulse sending process until the water outlet end A of the three-way valve reaches the fully closed state or \(T_{liquid}\leq25^{\circ}C\). After the three-way valve actuator receives 15 pulses during the closing valve process, the water outlet end A of the three-way valve reaches the fully closed state. For each pulse received by the actuator, the valve closing runs \(6^{\circ}\);

[0083] If the required frequency \(f_{demand}\) of the water pump is greater than \(f_{min\_safe}\), set the water pump frequency \(f = f_{demand}\).

[0084] Scenario B: When ΔT (real-time) > ΔT (design)

[0085] If the outlet A of the three-way valve is not fully open, the valve opening logic is triggered, and the outlet A of the three-way valve is opened by pressing the pulse until the outlet A of the three-way valve is fully open. At this time, the valve is opened first to utilize the radiator's potential.

[0086] If the outlet A of the three-way valve is fully open, and ΔT (real-time) is still greater than ΔT (design) + tolerance, then the frequency f of the variable frequency pump is increased according to f_demand.

[0087] Step 4: Over-temperature alarm. When ΔT (real-time) > ΔT (design), the frequency of the variable frequency water pump f >= 50Hz, the water end A of the three-way valve is fully open and the liquid temperature T continues to rise, an over-temperature alarm signal is output.

[0088] This application dynamically selects an adjustment strategy based on the comparison results and trends of the real-time calculated temperature difference ΔT(real-time) = T_liquid - T_loop and the preset target temperature difference ΔT(design). When the heat dissipation demand decreases, it prioritizes fine-step closing (until possible full closure) by sending discrete "valve closing" pulse commands to the three-way valve actuator, and only reduces the pump frequency to the minimum safe speed (f_min_safe) when necessary. When the heat dissipation demand increases, it prioritizes fine-step opening (until fully open) by sending discrete "valve opening" pulse commands to the three-way valve actuator, and only increases the pump frequency when the valve is fully open and the demand is still insufficient.

[0089] In this application, the valve opening is adjusted only by receiving discrete pulse commands, with each pulse corresponding to a fixed, small change in the valve core position. A pulse command is only triggered when the change in coolant temperature (T_coolant) within a specific time window (Δt) exceeds a preset threshold (ΔT_threshold). This mechanism aims to minimize the number of ineffective valve movements at intermediate openings. This application utilizes changes in the T_loop to predict the changing trend of heat dissipation demand, thereby triggering the adjustment actions (valve opening / closing / frequency adjustment) in step 2 in advance, significantly shortening the system response time.

[0090] Specifically, the technical effects of this application can be reflected in:

[0091] 1. Revolutionary improvement in response speed

[0092] For changes in heat dissipation demand caused by sudden changes in ambient temperature (e.g., ±10℃ / min) or sudden changes in unit power (>10%), the system flow rate is generally twice the system volume, and one cycle time is 30 seconds. The impact of these environmental changes on temperature does not exceed one cycle time. This application can accurately calculate the response scheme with a single set of data, thus controlling the temperature stabilization time to within 30 seconds. In contrast, the traditional industrial frequency pump three-way valve scheme requires approximately 5-7 cycles (average 6 cycles) for the system temperature to stabilize, resulting in a stabilization time of approximately 180 seconds. Furthermore, due to the limitation of the three-way valve's step distance, it is impossible to accurately control the final temperature, and repeated adjustments are even required near the target value. In contrast, the single frequency converter scheme requires approximately 3-5 cycles (average 4 cycles) for the system temperature to stabilize, resulting in a stabilization time of approximately 120 seconds. By comparison, this application far surpasses what can be achieved by simply optimizing the frequency converter pump or three-way valve. It is a direct result of the combined effect of feedforward mechanisms and collaborative decision-making, effectively avoiding performance degradation or protective shutdown of equipment due to excessive temperature fluctuations.

[0093] 2. Lifespan of key components doubled

[0094] The number of three-way valve actuations (open / close pulses) is reduced by more than 60%. More importantly, it completely eliminates frequent micro-oscillations in the intermediate opening range (the main cause of severe local wear of gears and oxidation failure of microswitch contacts in existing technologies). Taking a 6MW unit in a CGN wind farm in Xinjiang as an example, the three-way valve actuates 748 times / day during peak periods (approximately 4 months) and 50 times / day during off-peak periods (approximately 5 months), resulting in more than 118,000 actuations per year and an average service life of about 2 years. This patent, combined with frequency conversion control, reduces the operating temperature of the three-way valve, thereby reducing the number of actuations and the peak period. The number of actuations during peak periods can be reduced to less than 150 times (the time can be shortened to less than 4 months), and the number of actuations during off-peak periods can be reduced to 50 times / day (which can be increased to 8 months), resulting in less than 30,000 actuations per year and an increased service life of up to 7 years. The overall effect significantly improves its theoretical average service life.

[0095] The effective operating time of the water pump in the low-temperature range (<20℃) (equivalent to the operating time at standard speed) is reduced by 20-30%, and frequent start-stop and long-term high-speed operation at industrial frequency are avoided. Its theoretical average service life is increased from about 3 years in the existing solution to more than 5 years (an increase of 25%), and the increase in service life is significantly greater than expected by applying variable frequency technology alone.

[0096] 3. Significantly reduced energy consumption and efficient operation

[0097] Under conditions of low to medium ambient temperature and low to medium load on the unit for most of the year, the system avoids the significant ineffective flow and bypass energy loss that occurs in existing constant-speed pump systems or simple variable frequency systems (which still require frequent adjustment of the three-way valve) during low demand by prioritizing and finely closing / closing the three-way valve in conjunction with the pump speed reduction. Taking a 6MW unit in a CGN wind farm in Xinjiang as an example, the pump has a rated power of 5.5kW and an annual operating time of approximately 6000 hours. Under traditional power frequency operation, the annual electricity consumption is 33000kWh; with a single variable frequency solution, the annual electricity consumption is 31350kWh, resulting in an annual saving of 1650kWh; and with this application, the annual electricity consumption is 28380kWh, resulting in an annual saving of 4620kWh. Simultaneously, the coordinated control strategy deliberately guides the pump to operate in the high-efficiency range, avoiding the severe pump efficiency degradation that might occur with simple variable frequency systems.

[0098] 4. Enhanced temperature control accuracy and stability: Dual temperature feedback (T_liquid + T_loop) and feedforward-feedback composite control, combined with refined actuator actions, reduce the temperature fluctuation range of the cooled equipment by more than 50%, improving the reliability and lifespan of the equipment.

[0099] 5. The risk of overcooling and condensation is fundamentally reduced: Through T-loop feedforward and coordinated control, the system flow can be reduced in advance and gradually in low-temperature environments (prioritizing valve closure to stabilize flow), effectively avoiding the problem of sudden temperature drop caused by residual coolant in the radiator and condensation caused by excessively low inlet temperature of heat-generating components.

[0100] Taking a 2MW wind turbine unit in a wind farm in Inner Mongolia as an example, the controller uses a Siemens S7-1200 PLC to achieve:

[0101] When the ambient temperature drops sharply from 10℃ to -5℃ (simulating a blizzard): dT_loop / dt = -0.25℃ / s → triggering the anti-freeze mode; the step size S automatically increases to 3 times the normal value, and the three-way valve closes within 30 seconds; the pump frequency compensation factor α=0.5, maintaining the pipeline flow velocity >1.2m / s; result: no freezing alarm, and the system energy consumption is reduced by 37% compared to the single frequency converter solution.

[0102] These effects, particularly the order-of-magnitude improvement in response speed, the doubling of the lifespan of key components (three-way valve), and the significant energy savings achieved while ensuring system performance, are the synergistic effects and unexpected technical benefits brought about by the specific collaborative control logic (fine stepping valve + variable frequency pump + environmental feedforward + temperature difference-based decision-making) proposed in this invention. These effects cannot be naturally obtained by those skilled in the art through simple combinations of existing technologies (such as using a frequency converter to drive the pump and a common controller to switch the three-way valve).

[0103] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A three-way valve stepper motor and variable frequency pump coordinated control system based on the rate of change of temperature difference, characterized in that, The three-way valve stepper and variable frequency pump coordinated control system includes: a pump station, a radiator, a heat-generating device to be cooled, and a control terminal; the heat-generating device to be cooled is the component in the wind turbine that needs heat dissipation. The pump station is connected to the heat-generating equipment via a water-cooling circuit to cool the equipment. The pump station also connects to a radiator (9) via a built-in three-way valve (8) to control the temperature of the medium in the water-cooling circuit. The control terminal controls the variable frequency water pump (2) and the three-way valve (8) in the pump station based on the collected ambient temperature information, cooling circuit monitoring parameters and preset control algorithm, so as to complete the temperature control of the heat-generating equipment; The three-way valve (8) includes an inlet end AB, an outlet end A and an outlet end B. The inlet end AB is connected to the pump station output pipe, the outlet end A is connected to the inlet of the radiator (9), the outlet of the radiator (9) is connected to the heating device, and the outlet end B is connected to the heating device. The control terminal uses the following control algorithm to control the variable frequency water pump (2) and the three-way valve (8), including: Initially, the three-way valve switches to internal circulation, meaning inlet AB is responsible for water intake, outlet B is responsible for water output, outlet A is closed, and the variable frequency water pump is controlled to operate at the lowest frequency, while the cooling water circuit liquid temperature is monitored. If the medium T_liquid at the inlet of the heating equipment in the cooling circuit is ≤23℃, start the heater until the medium temperature is greater than 23℃, and then the wind turbine will run; if the liquid temperature T_liquid is >23℃, the wind turbine will run. The control algorithm also includes: initial temperature rise and valve opening triggering. When T_liquid > 25℃ and T_liquid continues to rise, that is, when the liquid temperature change ΔT_liquid ≥ ΔT_threshold ℃ in each measurement cycle, the control end sends an opening pulse command to the actuator of the three-way valve (8) to open the outlet A according to the pulse. And repeat the process of judging the liquid temperature and sending pulses until the outlet A of the three-way valve reaches the fully open state; Among them, after the actuator of the three-way valve receives 15 pulses, the outlet A of the three-way valve reaches the fully open state. For each pulse received by the actuator, the valve opening changes by 6°. The control algorithm further includes: real-time coordinated control based on the real-time temperature difference ΔT between the liquid temperature T_liquid and the ambient temperature T_loop, including: Based on the real-time temperature difference ΔTreal-time and the design temperature difference ΔTdesign, calculate the required frequency fdemand of the variable frequency pump to ensure that ΔTreal-time ≈ ΔTdesign ± tolerance. 1) When ΔT_real-time < ΔT_design, or T_fluid < T_set_low, If the pump demand frequency f_demand ≤ f_min_safe, then set the pump frequency f = f_min_safe. Simultaneously triggering the three-way valve closing logic judgment, including: if the liquid temperature (T_liquid) drops and the temperature drop is ≥ ΔT_threshold ℃ within a preset period, send a valve closing pulse command to the three-way valve actuator, and repeat this judgment and pulse sending process until the outlet A of the three-way valve reaches the fully closed state or T_liquid ≤ 25℃. During the valve closing process, after the three-way valve actuator receives 15 pulses, the outlet A of the three-way valve reaches the fully closed state. For each pulse received by the actuator, the valve closing degree moves by 6°. If the pump demand frequency f_demand > f_min_safe, set the pump frequency f = f_demand; 2) When ΔT_real-time > ΔT_design If the outlet A of the three-way valve is not fully open, the valve opening logic is triggered, and the outlet A of the three-way valve is opened by pressing the pulse until the outlet A of the three-way valve is fully open. If the outlet A of the three-way valve is fully open, and ΔT in real time is still greater than ΔT design plus tolerance, then the frequency f of the variable frequency pump should be increased according to f_demand.

2. The three-way valve stepper and variable frequency pump coordinated control system as described in claim 1, characterized in that, The control algorithm also includes: over-temperature alarm, When ΔT_real-time > ΔT_design, the frequency of the variable frequency water pump f >= 50Hz, the water end A of the three-way valve is fully open and the liquid temperature T_ continues to rise, an over-temperature alarm signal is output.

3. The three-way valve stepper and variable frequency pump coordinated control system as described in claim 1, characterized in that, The pump station includes: a frequency converter, a frequency converter water pump (2), a first pressure sensor (51), a second pressure sensor (52), a first temperature sensor (61), and a second temperature sensor (62); The second pressure sensor (52) and the second temperature sensor (62) are located upstream of the variable frequency water pump (2) and downstream of the heating device. The first pressure sensor (51) is located upstream of the downstream transmitting device of the variable frequency water pump. The first temperature sensor (61) is located upstream of the downstream heating device of the radiator (9). The frequency converter controls the frequency converter water pump (2) based on the control terminal signal.

4. The three-way valve stepper and variable frequency pump coordinated control system as described in claim 3, characterized in that, The pumping station also includes a buffer tank (1), which is located upstream of the variable frequency water pump (2).

5. The three-way valve stepper and variable frequency pump coordinated control system as described in claim 3, characterized in that, The pumping station also includes a flow meter (7), which is located downstream of the variable frequency pump (2).

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