Control system and method for nitrogen constant pressure system of hot water storage tank

Abstract

The invention discloses a hot water storage tank nitrogen constant pressure system control system and method.The system comprises a cold water tank and a hot water tank, one end of the hot water tank is connected with the first end of the cold water tank, and the second end of the cold water tank is connected with a cold water tank liquid level control module; an air temperature control module is connected between the third end of the cold water tank and the other end of the hot water tank; the cold water tank is provided with a first nitrogen heater, the hot water tank is provided with a second nitrogen heater, and the first nitrogen heater and the second nitrogen heater are respectively connected with an external heat source; and the cold water tank and the hot water tank are respectively provided with an overpressure deflation valve.

Description

Technical Field

[0001] The present invention belongs to the technical field of energy storage, and in particular relates to a control system and method for a nitrogen constant pressure system in a hot water storage tank. Background Art

[0002] Advanced adiabatic compressed air energy storage (AA-CAES) is a relatively mature and widely used non-regenerative compressed air energy storage method. It primarily uses a heat exchanger to store the heat of compression during air compression in a heat storage device. During power generation, the heat in the heat storage device heats high-pressure air, which then drives an air turbine to generate power. Currently, heat storage systems in compressed air energy storage power plants mostly use high-temperature hot water to store heat, typically at 160-190°C. To prevent the hot water from vaporizing and affecting system operation, it must be maintained at a stable pressure. Currently, nitrogen is the most common constant-pressure medium in hot water storage tanks.

[0003] The nitrogen constant pressure system uses the compressibility of inert gas to compensate for changes in water volume in the hot water storage system and maintain a constant pressure system. During the hot water storage and heat release process, the pressurized water in the storage tank is circulated for heating and cooling. The nitrogen in the hot water storage system is affected by the temperature in the water tank, resulting in large pressure fluctuations in the hot water storage tank. If you are not careful, it will cause the hot water storage tank system to overpressure. Summary of the Invention

[0004] The purpose of the present invention is to overcome the problem of pressure fluctuation in hot water storage tanks of compressed air energy storage power stations, and proposes a control system and method for a hot water storage tank nitrogen constant pressure system.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions: In a first aspect, the present invention provides a hot water storage tank nitrogen constant pressure system control system, comprising: A cold water tank and a hot water tank, wherein one end of the hot water tank is connected to the first end of the cold water tank, the second end of the cold water tank is connected to a cold water tank liquid level control module, and the third end of the cold water tank is connected to the other end of the hot water tank to an air temperature control module; The cold water tank is equipped with a first nitrogen heater, and the hot water tank is equipped with a second nitrogen heater. The first nitrogen heater and the second nitrogen heater are respectively connected to an external heat source; and an overpressure relief valve is installed on both the cold water tank and the hot water tank.

[0006] Furthermore, a first electric shut-off valve is connected between one end of the hot water tank and the first end of the cold water tank, a nitrogen filling point is set between the first electric shut-off valve and the first end of the hot water tank, and a hot water tank overpressure relief valve, a hot water tank temperature gauge, and a hot water tank pressure gauge are installed on the hot water tank.

[0007] Furthermore, the cold water tank level control module includes a working fluid pressure pump, a normal pressure water tank and a cold water tank level gauge, one end of the working fluid pressure pump and one end of the normal pressure water tank are connected to the second end of the cold water tank, the other end of the working fluid pressure pump is connected to the other end of the normal pressure water tank, and the cold water tank level gauge is installed on the cold water tank; A fourth electric shut-off valve is provided between one end of the working fluid pressure pump and the second end of the cold water tank, a fifth electric shut-off valve is provided between the other end of the working fluid pressure pump and the other end of the atmospheric pressure water tank, and a sixth electric shut-off valve is provided between one end of the atmospheric pressure water tank and the second end of the cold water tank; The cold water tank is equipped with a cold water tank overpressure relief valve, a cold water tank temperature gauge and a cold water tank pressure gauge.

[0008] Furthermore, the air temperature control module includes a working fluid pressure pump group, a common heat exchanger, an air duct, a first temperature meter, a second temperature meter, a flow meter and a hot water tank level meter; One end of the working fluid pressurizing pump group is connected to the hot water tank, the other end of the working fluid pressurizing pump group is connected to the first end of the shared heat exchanger, the second end of the shared heat exchanger is connected to the third end of the cold water tank, the third end of the shared heat exchanger is connected to one end of the air pipe, a first thermometer is installed between the third end of the shared heat exchanger and one end of the air pipe, the fourth end of the shared heat exchanger is connected to the other end of the air pipe, a second thermometer and a flow meter are installed between the fourth end of the shared heat exchanger and the other end of the air pipe, and the hot water tank liquid level gauge is installed on the hot water tank.

[0009] Furthermore, one end of the seventh electric shut-off valve is connected between one end of the working fluid pressure pump group and the hot water tank, and the other end of the seventh electric shut-off valve is connected between the other end of the working fluid pressure pump group and the first end of the shared heat exchanger; A second electric shut-off valve is connected between one end of the working fluid pressurizing pump group and one end of the seventh electric shut-off valve, a third electric shut-off valve is connected between the other end of the working fluid pressurizing pump group and the other end of the seventh electric shut-off valve, and an eighth electric shut-off valve is connected between the second end of the shared heat exchanger and the third end of the cold water tank; The working fluid booster pump group, the second electric shut-off valve, the third electric shut-off valve, the seventh electric shut-off valve, and the eighth electric shut-off valve are interlocked with the cold water tank level gauge; The working medium pressure pump group, the second electric shut-off valve, the third electric shut-off valve, the seventh electric shut-off valve, and the eighth electric shut-off valve are interlocked with the hot water tank liquid level gauge.

[0010] In a second aspect, the present invention provides a method for controlling a hot water storage tank nitrogen constant pressure system, using the hot water storage tank nitrogen constant pressure system control system, comprising the following steps: During the heat storage and heat release process, the air temperature control module adjusts the temperature of the hot water tank, controls the nitrogen temperature in the cold water tank through the first nitrogen heater, and controls the nitrogen temperature in the hot water tank through the second nitrogen heater; When there is insufficient water in the cold water tank, the cold water tank liquid level control module is used to control the liquid level of the cold water tank. When the pressure of the cold water tank or the hot water tank reaches a first overpressure value, the cold water tank liquid level control module is disconnected. When the pressure of the cold water tank or the hot water tank reaches a second overpressure value, the overpressure relief valve of the cold water tank or the hot water tank is opened.

[0011] Furthermore, the control method of the first nitrogen heater and the second nitrogen heater is: The pressure setting value of the cold water tank and the first fine-tuning signal are summed as the SP value of the first PID controller. The measured value of the cold water tank pressure gauge is processed by the filter block LEADLAG and used as the PV value of the first PID controller. The SP value of the first PID controller and the PV value of the first PID controller are used as the SP value of the second PID controller after the control operation of the first PID controller; The measured value of the cold water tank temperature meter is processed by the filter block LEADLAG and used as the PV value of the second PID controller; The SP value of the second PID controller and the PV value of the second PID controller are used as the output value of the actuator of the first nitrogen heater after the control operation of the second PID controller; The pressure setting value of the hot water tank and the second fine-tuning signal are summed as the SP value of the third PID controller. The measured value of the hot water tank pressure gauge is processed by the filter block LEADLAG and used as the PV value of the third PID controller. The SP value of the third PID controller and the PV value of the third PID controller are used as the SP value of the fourth PID controller after the control operation of the third PID controller; The measured value of the hot water tank temperature meter is processed by the filter block LEADLAG and used as the PV value of the fourth PID controller; The SP value and the PV value of the fourth PID controller are used as the actuator output value of the second nitrogen heater after being subjected to control calculation by the fourth PID controller.

[0012] Furthermore, the control method of the working fluid pressurizing pump group is: The measured value of the second temperature meter is processed by the filter block LEADLAG as the PV value of the fifth PID controller, and the measured value of the first temperature meter is processed by the filter block LEADLAG as the PV value of the sixth PID controller; The temperature setting value of the air duct and the third fine-tuning signal are summed as the SP value of the fifth PID controller. The SP value of the fifth PID controller and the PV value of the fifth PID controller are subjected to a control operation by the fifth PID controller to obtain an output value of the fifth PID controller. The temperature setting value of the air duct and the fourth fine-tuning signal are summed as the SP value of the sixth PID controller. The SP value of the sixth PID controller and the PV value of the sixth PID controller are subjected to a PID control operation to obtain an output value of the sixth PID controller. The measured value of the first temperature meter, the measured value of the second temperature meter and the measured value of the flow meter are used as the feedforward value of the fifth PID controller after being calculated by the first function; The measured value of the first temperature meter, the measured value of the second temperature meter and the measured value of the flow meter are used as the feedforward value of the sixth PID controller after being calculated by the second function; The first and second functions are specifically:

[0013]

[0014] in, represents the first function, represents the second function, Indicates the measured value of the flow meter, represents the measured value of the second thermometer, represents the measured value of the first thermometer, 、 、 、 、 、 represents a constant; The measured value of the cold water tank level meter is processed by the filter block LEADLAG and used as the switching value after the sum of the output value of the fifth PID controller and the feedforward value of the fifth PID controller. When the measured value of the cold water tank level meter is less than the preset threshold value of the cold water tank level, the output of the working fluid pressurizing pump group is 0; The measured value of the hot water tank level gauge is processed by the filter block LEADLAG and used as the switching value after the sum of the output value of the sixth PID controller and the feedforward value of the sixth PID controller. When the measured value of the hot water tank level gauge is less than the preset threshold of the cold water tank level, the output of the working fluid booster pump group is 0; The final outputs of the fifth PID controller and the sixth PID controller are selected by the switching block. When the system is in the heat storage mode, the output of the working fluid pressurizing pump group is the output instruction of the fifth PID controller. When the system is in the heat release mode, the output of the working fluid pressurizing pump group is the output instruction of the sixth PID controller.

[0015] Furthermore, the method further comprises the following steps: The cold water tank liquid level control module controls the liquid level of the cold water tank. When the water volume in the normal pressure water tank is lower than the preset water volume threshold, the liquid level of the cold water tank is controlled by the working fluid booster pump, the fourth electric shut-off valve, the fifth electric shut-off valve, and the cold water tank liquid level gauge of the cold water tank liquid level control module; when the pressure of the cold water tank exceeds the preset pressure threshold, the cold water tank liquid level control module releases the pressure.

[0016] Furthermore, the control method of the working fluid booster pump is: The measured value of the cold water tank level meter is processed by the filter block LEADLAG and used as the PV value of the PID controller; The liquid level setting value of the cold water tank and the fine-tuning signal are summed as the SP value of the PID controller; The PV value and the SP value of the PID controller are subjected to PID calculation by the PID controller to obtain the output value of the actuator of the working fluid booster pump for regulating the liquid level of the cold water tank by the cold water tank level control module.

[0017] Compared with the prior art, the present invention has the following beneficial technical effects: The present invention proposes a hot water storage tank nitrogen constant pressure system control system, which controls the nitrogen temperature of the hot and cold water tanks, the liquid level of the cold water tank, and the air temperature, thereby ensuring the safe, stable, and efficient operation of the entire process system. For a specific nitrogen constant pressure system, the stable operation of the nitrogen constant pressure system ensures the pressure of the hot water storage tank, ensuring that the pressure of the hot water storage tank fluctuates within a reasonable range, which can effectively prevent the situation of reserving too much pressure margin when designing the storage tank, and effectively reduce the engineering cost of the pressurized water storage tank.

[0018] The present invention combines a typical hot water heat storage nitrogen constant pressure process system and specifically proposes a complete control method to ensure a good control effect of the nitrogen constant pressure system and ensure the safe and stable operation of the power station; it is conducive to achieving the stable operation of the constant pressure system, ensuring that the water tank pressure is within a reasonable range, ensuring control accuracy, and realizing precise control of the pressures of the hot and cold water tanks, so that the minimum margin can be selected when selecting the pressure of the hot and cold water storage tanks, effectively reducing the engineering cost of pressurized hot and cold water storage tanks, and effectively ensuring the safe and stable operation of pressurized hot and cold water tanks in compressed air energy storage power stations, further promoting the development of compressed air energy storage technology, and ensuring the absorption of new energy base power stations, which has positive social significance. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The drawings described herein are for illustrative purposes only and are not intended to limit the scope of the present invention in any way. In addition, the shapes and proportional dimensions of the components in the drawings are only schematic and are used to help understand the present invention, and are not intended to specifically limit the shapes and proportional dimensions of the components of the present invention. In the drawings: Figure 1 This is a schematic diagram of the process configuration of a nitrogen constant pressure system for a hot water storage tank according to the present invention.

[0020] Figure 2 This is a control logic diagram of the first nitrogen heater and the second nitrogen heater.

[0021] Figure 3 This is the control logic diagram of the working fluid pressurizing pump group.

[0022] Figure 4 This is the control logic diagram of the working fluid pressure pump.

[0023] Among them, 1 - cold water tank, 2 - first nitrogen heater, 3 - second nitrogen heater, 4 - hot water tank, 5 - working fluid pressure pump group, 6 - shared heat exchanger, 7 - working fluid pressure pump, 8 - normal pressure water tank, 9 - cold water tank overpressure release valve, 10 - cold water tank temperature gauge, 11 - cold water tank pressure gauge, 12 - first electric shut-off valve, 13 - nitrogen filling point, 14 - hot water tank temperature gauge, 15 - hot water tank pressure gauge, 16 - hot water tank Overpressure release valve, 17—hot water tank liquid level gauge, 18—second electric shut-off valve, 19—third electric shut-off valve, 20—first temperature gauge, 21—second temperature gauge, 22—flow meter, 23—cold water tank liquid level gauge, 24—fourth electric shut-off valve, 25—fifth electric shut-off valve, 26—sixth electric shut-off valve, 27—external heat source, 28—air pipe, 29—seventh electric shut-off valve, 30—eighth electric shut-off valve. DETAILED DESCRIPTION

[0024] In order to enable those skilled in the art to better understand the solutions of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts should fall within the scope of protection of the present invention.

[0025] It should be noted that when an element is referred to as being "disposed on" another element, it may be directly on the other element or there may be an element centered thereon. When an element is referred to as being "connected to" another element, it may be directly connected to the other element or there may be an element centered thereon. The terms "vertical," "horizontal," "left," "right," and similar expressions used herein are for illustrative purposes only and do not represent the only embodiments.

[0026] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one skilled in the art to which this invention pertains. The terms used in this specification of the present invention are for the purpose of describing specific embodiments only and are not intended to limit the present invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0027] It should be noted that the terms "first", "second", etc. in the description and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that the numbers used in this way can be interchanged where appropriate, so that the embodiments of the present invention described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions. For example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0028] Example 1 See also Figure 1 , a hot water storage tank nitrogen constant pressure system control system, comprising: A cold water tank 1 and a hot water tank 4, one end of the hot water tank 4 is connected to the first end of the cold water tank 1, the second end of the cold water tank 1 is connected to a cold water tank level control module, and an air temperature control module is connected between the third end of the cold water tank 1 and the other end of the hot water tank 3; The cold water tank 1 is equipped with a first nitrogen heater 2, and the hot water tank 4 is equipped with a second nitrogen heater 3. The first nitrogen heater 2 and the second nitrogen heater 3 are respectively connected to an external heat source 27; and both the cold water tank 1 and the hot water tank 4 are equipped with an overpressure relief valve.

[0029] A first electric shut-off valve 12 is connected between one end of the hot water tank 4 and the first end of the cold water tank 1. A nitrogen filling point 13 is set between the first electric shut-off valve 12 and the first end of the hot water tank 4. A hot water tank overpressure relief valve 16, a hot water tank thermometer 14, and a hot water tank pressure gauge 15 are installed on the hot water tank 4.

[0030] The cold water tank level control module includes a working fluid pressure pump 7, a normal pressure water tank 8 and a cold water tank level gauge 23. One end of the working fluid pressure pump 7 and one end of the normal pressure water tank 8 are connected to the second end of the cold water tank 1, and the other end of the working fluid pressure pump 7 is connected to the other end of the normal pressure water tank 8. The cold water tank level gauge 23 is installed on the cold water tank 1. A fourth electric shut-off valve 24 is provided between one end of the working fluid pressure pump 7 and the second end of the cold water tank 1, a fifth electric shut-off valve 25 is provided between the other end of the working fluid pressure pump 7 and the other end of the atmospheric pressure water tank 8, and a sixth electric shut-off valve 26 is provided between one end of the atmospheric pressure water tank 8 and the second end of the cold water tank 1; The cold water tank 1 is equipped with a cold water tank overpressure relief valve 9, a cold water tank temperature gauge 10 and a cold water tank pressure gauge 11.

[0031] The air temperature control module includes a working fluid pressure pump group 5, a shared heat exchanger 6, an air pipe 28, a first temperature meter 20, a second temperature meter 21, a flow meter 22 and a hot water tank level meter 17; One end of the working fluid pressurizing pump group 5 is connected to the hot water tank 3, the other end of the working fluid pressurizing pump group 5 is connected to the first end of the shared heat exchanger 6, the second end of the shared heat exchanger 6 is connected to the third end of the cold water tank 1, the third end of the shared heat exchanger 6 is connected to one end of the air pipe 28, a first thermometer 20 is installed between the third end of the shared heat exchanger 6 and one end of the air pipe 28, the fourth end of the shared heat exchanger 6 is connected to the other end of the air pipe 28, a second thermometer 21 and a flow meter 22 are installed between the fourth end of the shared heat exchanger 6 and the other end of the air pipe 28, and the hot water tank liquid level meter 17 is installed on the hot water tank 3.

[0032] One end of the seventh electric shut-off valve 29 is connected between one end of the working fluid pressure pump group 5 and the hot water tank 3 , and the other end of the seventh electric shut-off valve 29 is connected between the other end of the working fluid pressure pump group 5 and the first end of the shared heat exchanger 6 ; A second electric shut-off valve 18 is connected between one end of the working fluid pressurizing pump group 5 and one end of the seventh electric shut-off valve 29, a third electric shut-off valve 19 is connected between the other end of the working fluid pressurizing pump group 5 and the other end of the seventh electric shut-off valve 29, and an eighth electric shut-off valve 30 is connected between the second end of the shared heat exchanger 6 and the third end of the cold water tank 1; The working medium booster pump group 5, the second electric shut-off valve 18, the third electric shut-off valve 19, the seventh electric shut-off valve 29, and the eighth electric shut-off valve 30 are interlocked with the cold water tank level gauge 23; The working medium booster pump group 5 , the second electric shut-off valve 18 , the third electric shut-off valve 19 , the seventh electric shut-off valve 29 , and the eighth electric shut-off valve 30 are interlocked with the hot water tank level gauge 17 .

[0033] A method for controlling a hot water storage tank nitrogen constant pressure system, using a hot water storage tank nitrogen constant pressure system control system, comprises the following steps: During the heat storage and heat release process, the air temperature control module adjusts the temperature of the hot water tank 4, controls the nitrogen temperature in the cold water tank 1 through the first nitrogen heater 2, and controls the nitrogen temperature in the hot water tank 4 through the second nitrogen heater 3; When there is insufficient water in the cold water tank 1, the cold water tank liquid level control module is used to control the liquid level of the cold water tank 1. When the pressure of the cold water tank 1 or the hot water tank 4 reaches a first overpressure value, the cold water tank liquid level control module is disconnected. When the pressure of the cold water tank 1 or the hot water tank 4 reaches a second overpressure value, the overpressure relief valve of the cold water tank 1 or the hot water tank 4 is opened.

[0034] The control method of the first nitrogen heater 2 and the second nitrogen heater 3 is: The pressure setting value of the cold water tank 1 and the first fine-tuning signal are summed as the SP value of the first PID controller, and the measurement value of the cold water tank pressure gauge 11 is processed by the filter block LEADLAG and used as the PV value of the first PID controller; The SP value of the first PID controller and the PV value of the first PID controller are used as the SP value of the second PID controller after the control operation of the first PID controller; The measured value of the cold water tank thermometer 10 is processed by the filter block LEADLAG and used as the PV value of the second PID controller; The SP value and the PV value of the second PID controller are used as the output value of the actuator of the first nitrogen heater 2 after the control operation of the second PID controller; The pressure setting value of the hot water tank 4 and the second fine-tuning signal are summed as the SP value of the third PID controller, and the measurement value of the hot water tank pressure gauge 15 is processed by the filter block LEADLAG and used as the PV value of the third PID controller; The SP value of the third PID controller and the PV value of the third PID controller are used as the SP value of the fourth PID controller after the control operation of the third PID controller; The measured value of the hot water tank temperature meter 14 is processed by the filter block LEADLAG and used as the PV value of the fourth PID controller; The SP value and the PV value of the fourth PID controller are used as the actuator output value of the second nitrogen heater 3 after being subjected to control calculation by the fourth PID controller.

[0035] The control method of the working fluid booster pump group 5 is: The measurement value of the second temperature meter 21 is processed by the filter block LEADLAG and used as the PV value of the fifth PID controller. The measurement value of the first temperature meter 20 is processed by the filter block LEADLAG and used as the PV value of the sixth PID controller. The temperature setting value of the air duct 28 and the third fine-tuning signal are summed to serve as the SP value of the fifth PID controller. The SP value of the fifth PID controller and the PV value of the fifth PID controller are subjected to a control operation by the fifth PID controller to obtain an output value of the fifth PID controller. The temperature setting value of the air duct 28 and the fourth fine-tuning signal are summed to serve as the SP value of the sixth PID controller. The SP value of the sixth PID controller and the PV value of the sixth PID controller are subjected to a PID control operation to obtain an output value of the sixth PID controller. The measured value of the first temperature meter 20, the measured value of the second temperature meter 21 and the measured value of the flow meter 22 are used as the feedforward value of the fifth PID controller after being calculated by the first function; The measured value of the first temperature meter 20, the measured value of the second temperature meter 21 and the measured value of the flow meter 22 are used as the feedforward value of the sixth PID controller after being calculated by the second function; The first and second functions are specifically:

[0036]

[0037] in, represents the first function, represents the second function, Indicates the measured value of flow meter 22, represents the measured value of the second thermometer 21, represents the measured value of the first thermometer 20, 、 、 、 、 、 represents a constant; The measured value of the cold water tank level meter 23 is processed by the filter block LEADLAG and used as the switching value after the sum of the output value of the fifth PID controller and the feedforward value of the fifth PID controller. When the measured value of the cold water tank level meter 23 is less than the preset threshold value of the cold water tank level, the output of the working fluid booster pump group 5 is 0; The measured value of the hot water tank level gauge 17 is processed by the filter block LEADLAG and used as the switching value after the sum of the output value of the sixth PID controller and the feedforward value of the sixth PID controller. When the measured value of the hot water tank level gauge 17 is less than the preset threshold value of the cold water tank level, the output of the working fluid booster pump group 5 is 0; The final outputs of the fifth PID controller and the sixth PID controller are selected by the switching block. When the system is in the heat storage mode, the output of the working fluid pressurizing pump group 5 is the output instruction of the fifth PID controller. When the system is in the heat release mode, the output of the working fluid pressurizing pump group 5 is the output instruction of the sixth PID controller.

[0038] The cold water tank liquid level control module controls the liquid level of the cold water tank 1. When the water volume in the normal pressure water tank 8 is lower than the preset water volume threshold, the liquid level of the cold water tank 1 is controlled by the working fluid booster pump 7, the fourth electric shut-off valve 24 and the fifth electric shut-off valve 25, and the cold water tank liquid level meter 23 of the cold water tank liquid level control module; when the pressure of the cold water tank 1 exceeds the preset pressure threshold, the cold water tank liquid level control module releases the pressure.

[0039] The control method of the working fluid booster pump 7 is: The measured value of the cold water tank level meter 23 is processed by the filter block LEADLAG and used as the PV value of the PID controller; The liquid level setting value of the cold water tank 1 and the fine-tuning signal are summed as the SP value of the PID controller; The PV value and the SP value of the PID controller are subjected to PID calculation by the PID controller to obtain the output value of the actuator of the working fluid booster pump 7 for adjusting the liquid level of the cold water tank 1 by the cold water tank level control module.

[0040] Example 2 See also Figure 1 The working process of the process system of this embodiment is as follows: During the heat storage and release process of the unit, the working fluid pressurizing pump group 5 and the electric shut-off valves 18, 19, 23, and 29 are used to jointly control the air temperature 20 and the air temperature 21 of the air pipe 28. The nitrogen temperature in the cold and hot water tanks is controlled by the first nitrogen heater 2 and the second nitrogen heater 3, thereby ensuring the nitrogen pressure in the cold and hot storage tanks. The interlocking control of the working fluid pressurizing pump group 5 and the electric shut-off valves 18, 19, 23, and 29 is achieved through the cold water tank liquid level measuring instrument 23 and the hot water tank liquid level measuring instrument 17. When the amount of water in the water tank is insufficient, the working fluid booster pump 7, the electric shut-off valves 25 and 26, and the cold water tank liquid level measuring instrument 23 jointly realize the liquid level control of the cold water tank to ensure that there is sufficient water in the system; in particular, when the pressure of the cold water tank or the hot water tank reaches a first overpressure value, the pressure measuring instruments 11, 15 and the electric shut-off valve 26 jointly realize pressure relief; when the pressure of the cold water tank or the hot water tank reaches a second overpressure value, the overpressure relief valves 9 and 16 respectively realize pressure relief to ensure system safety.

[0041] The nitrogen temperature control scheme of this nitrogen constant pressure system is as follows, see Figure 2 : The hot water heat storage system uses a nitrogen constant pressure system to maintain a certain storage tank pressure to ensure that the hot water in the hot water storage tank does not vaporize during the heat storage and release process of the unit, and at the same time ensure that the pressure of the cold and hot water storage tanks is maintained within a certain range. The nitrogen temperature in the cold and hot water tanks is adjusted through nitrogen heaters 2 and 3 in the cold and hot water tanks, so that the pressure in the water tank does not exceed the pressure during the heat storage and release process, ensuring the safe operation of the cold and hot water tanks themselves; The pressure setting value of the hot and cold water storage tanks is obtained by combining the maximum pressure resistance and safety margin originally designed for the storage tanks. The pressure setting value of the cold water storage tank is summed with the input signal A1 of the operator in the control system as the input value of the set value input terminal SP of the PID1 controller. The function of the input signal A1 here is mainly to facilitate the operator to make minor adjustments to the operating pressure value of the hot water storage tank. The logic here will impose certain restrictions on the value of the input signal A1 in combination with the design margin of the hot water storage tank pressure; the measurement value of the cold water storage tank pressure measuring instrument 11 installed on the hot water storage tank body is processed by the filter block LEADLAG and used as the input value of the process value input terminal PV of the PID1 controller. The function of the filter block LEADLAG here is to Its main function is to prevent signal jitter during pressure measurement; the output value of the PID1 controller is used as the input value of the set value input terminal SP of the PID2 controller, and the measurement value of the cold water tank temperature measuring instrument 10 installed on the hot water tank body is processed by the filter block LEADLAG and used as the input value of the process value input terminal PV of the PID2 controller. The function of the filter block LEADLAG here is mainly to prevent signal jitter during temperature measurement; through the series control of pressure and temperature, the pressure of the hot and cold water storage tanks is ultimately guaranteed to be within a reasonable range; the control scheme of the nitrogen heater 3 in the hot water storage tank is consistent with the control scheme of the nitrogen heater 2 in the cold water storage tank, only some parameters are selected inconsistently, which will not be repeated here.

[0042] For the control description of the working medium pressure pump group 5 in this embodiment, see Figure 3 : The control function of the working fluid booster pump group 5 is mainly to ensure that the air temperature at the air pipe outlet is within a reasonable range during the heat storage and heat release process of the unit, and at the same time ensure the safe and stable operation of the first working fluid pump; In the system heat storage mode, the air duct temperature set value and the operator's input signal A3 in the control system are summed and used as the input value of the set value input terminal SP of the PID5 controller. The function of the input signal A3 here is mainly to facilitate the operator to make minor adjustments to the air duct temperature operating value; the measurement value of the air duct temperature measuring instrument 21 is processed by the filter block LEADLAG and used as the input value of the process value input terminal PV of the PID5 controller. The function of the filter block LEADLAG here is mainly to prevent signal jitter during the air duct temperature measurement process; in the system heat release mode, the air duct temperature set value and the operator's input signal A4 in the control system are summed and used as the input value of the set value input terminal SP of the PID6 controller. The function of the input signal A3 here is mainly to facilitate the operator to make minor adjustments to the air duct temperature operating value; the measurement value of the air duct temperature measuring instrument 20 is processed by the filter block LEADLAG and used as the input value of the process value input terminal PV of the PID6 controller. The function of the filter block LEADLAG here is mainly to prevent signal jitter during the air duct temperature measurement process; The measured values ​​of the air duct temperature measuring instrument 20, the measured values ​​of the air duct flow measuring instrument 22 and the measured values ​​of the air duct temperature measuring instrument 21 are calculated by the function After the operation, it is used as the feedforward value output by the PID5 controller to ensure the rapid response of the air duct temperature during the heat storage process; the measured values ​​of the air duct temperature measuring instrument 20, the measured values ​​of the air duct flow measuring instrument 22 and the measured values ​​of the air duct temperature measuring instrument 21 are measured by the function After the calculation, it is used as the feedforward value output by the PID5 controller to ensure the rapid response of the air duct temperature during the heat release process; The measured value of the cold water tank liquid level measuring instrument 23 is processed by the filter block LEADLAG and used as the switching value after the output value of the PID5 controller and the feedforward value are summed. When the value of the liquid level measuring instrument 23 is less than 50, it can be adjusted according to the actual situation on site, and the output of the working fluid pressurizing pump group 5 is 0; the measured value of the hot water tank liquid level measuring instrument 17 is processed by the filter block LEADLAG and used as the switching value after the output value of the PID6 controller and the feedforward value are summed. When the value of the liquid level measuring instrument 17 is less than 50, the output of the working fluid pressurizing pump group 5 is 0, thereby ensuring the safe and stable operation of the unit during heat storage and heat release; function and Combined with the temperature rise and flow rate of the air duct, the feedforward values ​​of the PID5 and PID6 controllers are calculated to ensure that the control accuracy and speed meet the system operation requirements; function and The basic formula is as follows:

[0043] Where: —Measured value of flow measuring instrument 22, t / h; —Measured value of temperature measuring instrument 21, °C; —Measured value of the temperature measuring instrument 20, °C; , , —Constant, given according to the operating conditions during on-site commissioning, dimensionless;

[0044] Where: —Measured value of flow measuring instrument 22, t / h; —Measured value of temperature measuring instrument 21, °C; —Measured value of the temperature measuring instrument 20, °C; , , —Constant, given according to the operating conditions during on-site commissioning, dimensionless; The final outputs of the PID5 controller and the PID6 controller are subjected to mode judgment by the switching block T. When the system is in the heat storage mode, the output of the working fluid pressurizing pump group is the output instruction of the PID5 controller. When the system is in the heat release mode, the output of the working fluid pressurizing pump group is the output instruction of the PID6 controller. Through the implementation of the above control scheme, the temperature of the air medium can be controlled within a reasonable range during the heat storage and release process, while ensuring the safety of the system operation, thus safeguarding the safe and stable operation of the compressed air energy storage power station.

[0045] For the control description of the working medium pressure pump 7 in this embodiment, see Figure 4 : In order to ensure that the liquid level value in the cold water tank is maintained within a reasonable range, in this embodiment, the system maintains the liquid level of the cold water tank through the working fluid pressure pump 7; the measurement value of the cold water tank liquid level measuring instrument 23 is processed by the filter block LEADLAG and used as the input value PV of the PID controller. The cold water tank liquid level setting value SP and the input signal A of the operator in the control system are summed and used as the input value of the setting value input terminal SP of the PID controller. The role of the input signal A here is mainly to facilitate the operator to fine-tune the cold water tank liquid level setting value according to the actual operating conditions. The cold water tank liquid level setting value SP and the PV value are used as the input values ​​of the PID controller together. After the operation of the PID controller, the output value of the working fluid pressure pump 7 actuator for adjusting the cold water tank liquid level is obtained to ensure that the cold water tank liquid level is within a reasonable range.

[0046] Control instructions for each electric shut-off valve in this embodiment: The control of each electric shut-off valve mentioned in this embodiment is mainly to ensure that the regulation, protection and other functions of the unit during the heat storage and heat release process meet the on-site operation requirements. Combined with the operating procedures under each working state of this embodiment, the control scheme of each electric shut-off valve mentioned in this embodiment is relatively simple, so it will not be repeated here.

[0047] The working process of this embodiment is as follows: The working process of this embodiment mainly includes the following operating processes: a) Initial working fluid replenishment process of pressurized water energy storage system Electric shut-off valves 12, 18, 19, 24, 25, and 26 are closed, and electric shut-off valves 23 and 29 are opened. Nitrogen enters the system from nitrogen filling point 13 and is pressurized by an external compressor and transported to the cold water tank 1 and the hot water tank 4.

[0048] After nitrogen filling is completed, electric shut-off valves 12, 23, and 26 are closed, and electric shut-off valves 24 and 25 are opened. The system working fluid booster pump 7 replenishes water to the pressurized cold water tank; after the water replenishment is completed, the system's initial working fluid replenishment process is completed.

[0049] b) Heat storage process of pressurized water energy storage system Electric shut-off valves 24, 25, 26, and 29 are closed, and electric shut-off valves 12, 18, 19, and 23 are opened. Cold water flows out of the cold water tank 1, is heated by the air in the shared heat exchanger 6, and then enters the hot water tank 2 after being pressurized by the working fluid pressurizing pump group 5. Since the nitrogen temperature remains stable, the pressure fluctuation at this time is only caused by the change in the pressurized water volume.

[0050] c) Heat release process of pressurized water energy storage system Electric shut-off valves 24, 25, 26, and 29 are closed, and electric shut-off valves 12, 18, 19, and 23 are opened. Hot water flows out of the hot water tank 4, is pressurized by the working fluid pressurizing pump group 5, and enters the shared heat exchanger 6. It is cooled by air in the shared heat exchanger 6 and then enters the cold water tank 1. Since the nitrogen temperature remains stable, the pressure fluctuation at this time is only caused by the change in the pressurized water volume.

[0051] d) Overpressure relief process of pressurized water energy storage system After the pressure of the cold water tank 1 or the hot water tank 4 exceeds the first set value, the electric shut-off valves 24 and 25 are closed, and the electric shut-off valve 26 is opened, and the cold water in the cold water tank is discharged into the normal pressure water tank 7; After the pressure of the cold water tank 1 or the hot water tank 4 exceeds the second set value, the overpressure relief valve 9 or 16 opens to release the nitrogen in the tank into the atmosphere to protect the safety of the cold water tank and hot water tank equipment.

[0052] Many embodiments and applications beyond the examples provided will be apparent to those skilled in the art upon reading the foregoing description. Therefore, the scope of the present teachings should be determined not with reference to the foregoing description, but rather with reference to the preceding claims, along with the full scope of equivalents to which such claims are entitled. For the purpose of completeness, all articles and references, including the disclosures of patent applications and publications, are incorporated herein by reference. The omission of any aspect of the subject matter disclosed herein from the preceding claims is not a disclaimer of such subject matter, nor should it be interpreted that the applicants did not consider such subject matter to be part of the disclosed inventive subject matter.

[0053] The above content is a further detailed description of the present invention, and it cannot be considered that the specific implementation methods of the present invention are limited to these. For ordinary technicians in the technical field to which the present invention belongs, they can make several simple deductions or substitutions without departing from the concept of the present invention, which should be regarded as belonging to the scope of protection of the present invention determined by the submitted claims.

Claims

1. A hot water storage tank nitrogen constant pressure system control system, characterized in that: include: A cold water tank (1) and a hot water tank (4), wherein one end of the hot water tank (4) is connected to the first end of the cold water tank (1), the second end of the cold water tank (1) is connected to a cold water tank liquid level control module, and the third end of the cold water tank (1) is connected to the other end of the hot water tank (3) to an air temperature control module; The cold water tank (1) is equipped with a first nitrogen heater (2), and the hot water tank (4) is equipped with a second nitrogen heater (3). The first nitrogen heater (2) and the second nitrogen heater (3) are respectively connected to an external heat source (27). Both the cold water tank (1) and the hot water tank (4) are equipped with an overpressure relief valve.

2. A hot water storage tank nitrogen constant pressure system control system according to claim 1, characterized in that: A first electric shut-off valve (12) is connected between one end of the hot water tank (4) and the first end of the cold water tank (1); a nitrogen filling point (13) is provided between the first electric shut-off valve (12) and the first end of the hot water tank (4); and a hot water tank overpressure relief valve (16), a hot water tank temperature gauge (14), and a hot water tank pressure gauge (15) are installed on the hot water tank (4).

3. A hot water storage tank nitrogen constant pressure system control system according to claim 1, characterized in that: The cold water tank liquid level control module comprises a working fluid pressure pump (7), a normal pressure water tank (8) and a cold water tank liquid level gauge (23), one end of the working fluid pressure pump (7) and one end of the normal pressure water tank (8) are connected to the second end of the cold water tank (1), the other end of the working fluid pressure pump (7) is connected to the other end of the normal pressure water tank (8), and the cold water tank liquid level gauge (23) is installed on the cold water tank (1); A fourth electric shut-off valve (24) is provided between one end of the working fluid pressure pump (7) and the second end of the cold water tank (1), a fifth electric shut-off valve (25) is provided between the other end of the working fluid pressure pump (7) and the other end of the normal pressure water tank (8), and a sixth electric shut-off valve (26) is provided between one end of the normal pressure water tank (8) and the second end of the cold water tank (1); The cold water tank (1) is equipped with a cold water tank overpressure relief valve (9), a cold water tank temperature gauge (10) and a cold water tank pressure gauge (11).

4. A hot water storage tank nitrogen constant pressure system control system according to claim 3, characterized in that: The air temperature control module includes a working fluid pressure pump group (5), a shared heat exchanger (6), an air pipe (28), a first temperature meter (20), a second temperature meter (21), a flow meter (22), and a hot water tank level meter (17); One end of the working fluid pressurizing pump group (5) is connected to the hot water tank (3), the other end of the working fluid pressurizing pump group (5) is connected to the first end of the shared heat exchanger (6), the second end of the shared heat exchanger (6) is connected to the third end of the cold water tank (1), the third end of the shared heat exchanger (6) is connected to one end of the air pipe (28), a first thermometer (20) is installed between the third end of the shared heat exchanger (6) and one end of the air pipe (28), a fourth end of the shared heat exchanger (6) is connected to the other end of the air pipe (28), a second thermometer (21) and a flow meter (22) are installed between the fourth end of the shared heat exchanger (6) and the other end of the air pipe (28), and the hot water tank level meter (17) is installed on the hot water tank (3).

5. A hot water storage tank nitrogen constant pressure system control system according to claim 4, characterized in that: One end of the seventh electric shut-off valve (29) is connected between one end of the working fluid pressurizing pump group (5) and the hot water tank (3), and the other end of the seventh electric shut-off valve (29) is connected between the other end of the working fluid pressurizing pump group (5) and the first end of the shared heat exchanger (6); A second electric shut-off valve (18) is connected between one end of the working fluid pressurizing pump group (5) and one end of the seventh electric shut-off valve (29), a third electric shut-off valve (19) is connected between the other end of the working fluid pressurizing pump group (5) and the other end of the seventh electric shut-off valve (29), and an eighth electric shut-off valve (30) is connected between the second end of the shared heat exchanger (6) and the third end of the cold water tank (1); The working fluid booster pump group (5), the second electric shut-off valve (18), the third electric shut-off valve (19), the seventh electric shut-off valve (29), and the eighth electric shut-off valve (30) are interlocked with the cold water tank level gauge (23); The working fluid booster pump group (5), the second electric shut-off valve (18), the third electric shut-off valve (19), the seventh electric shut-off valve (29), and the eighth electric shut-off valve (30) are interlocked with the hot water tank level gauge (17).

6. A method for controlling a hot water storage tank nitrogen constant pressure system, using a hot water storage tank nitrogen constant pressure system control system according to any one of claims 1 to 5, characterized in that: The following steps are involved: During the heat storage and heat release process, the air temperature control module adjusts the temperature of the hot water tank (4), controls the nitrogen temperature in the cold water tank (1) through the first nitrogen heater (2), and controls the nitrogen temperature in the hot water tank (4) through the second nitrogen heater (3); When the amount of water in the cold water tank (1) is insufficient, the liquid level of the cold water tank (1) is controlled by the cold water tank liquid level control module. When the pressure of the cold water tank (1) or the hot water tank (4) reaches a first overpressure value, the cold water tank liquid level control module is disconnected. When the pressure of the cold water tank (1) or the hot water tank (4) reaches a second overpressure value, the overpressure relief valve of the cold water tank (1) or the hot water tank (4) is opened.

7. A hot water storage tank nitrogen constant pressure system control system according to claim 6, characterized in that: The control method of the first nitrogen heater (2) and the second nitrogen heater (3) is: The pressure setting value of the cold water tank (1) and the first fine-tuning signal are summed to serve as the SP value of the first PID controller, and the measured value of the cold water tank pressure gauge (11) is processed by the filter block LEADLAG to serve as the PV value of the first PID controller; The SP value of the first PID controller and the PV value of the first PID controller are used as the SP value of the second PID controller after the control operation of the first PID controller; The measured value of the cold water tank temperature meter (10) is processed by the filter block LEADLAG and used as the PV value of the second PID controller; The SP value of the second PID controller and the PV value of the second PID controller are used as the output value of the actuator of the first nitrogen heater (2) after the control operation of the second PID controller; The pressure setting value of the hot water tank (4) and the second fine-tuning signal are summed to serve as the SP value of the third PID controller, and the measurement value of the hot water tank pressure gauge (15) is processed by the filter block LEADLAG to serve as the PV value of the third PID controller; The SP value of the third PID controller and the PV value of the third PID controller are used as the SP value of the fourth PID controller after the control operation of the third PID controller; The measured value of the hot water tank temperature meter (14) is processed by the filter block LEADLAG and used as the PV value of the fourth PID controller; The SP value of the fourth PID controller and the PV value of the fourth PID controller are used as the output value of the actuator of the second nitrogen heater (3) after the control operation of the fourth PID controller.

8. A hot water storage tank nitrogen constant pressure system control method according to claim 6, characterized in that: The control method of the working fluid pressurizing pump group (5) is: The measured value of the second temperature meter (21) is processed by the filter block LEADLAG and used as the PV value of the fifth PID controller, and the measured value of the first temperature meter (20) is processed by the filter block LEADLAG and used as the PV value of the sixth PID controller; The temperature setting value of the air duct (28) and the third fine-tuning signal are summed as the SP value of the fifth PID controller, the SP value of the fifth PID controller and the PV value of the fifth PID controller are subjected to a control operation of the fifth PID controller to obtain an output value of the fifth PID controller, the temperature setting value of the air duct (28) and the fourth fine-tuning signal are summed as the SP value of the sixth PID controller, the SP value of the sixth PID controller and the PV value of the sixth PID controller are subjected to a PID control operation to obtain an output value of the sixth PID controller; The measured value of the first temperature meter (20), the measured value of the second temperature meter (21) and the measured value of the flow meter (22) are used as feedforward values ​​of the fifth PID controller after being operated by the first function; The measured value of the first temperature meter (20), the measured value of the second temperature meter (21) and the measured value of the flow meter (22) are used as the feedforward value of the sixth PID controller after being operated by the second function; The first function and the second function are specifically: in, represents the first function, represents the second function, represents the measured value of the flow meter (22), represents the measured value of the second thermometer (21), represents the measured value of the first thermometer (20), 、 、 、 、 、 represents a constant; The measured value of the cold water tank level meter (23) is processed by the filter block LEADLAG and used as the switching value after the sum of the output value of the fifth PID controller and the feedforward value of the fifth PID controller. When the measured value of the cold water tank level meter (23) is less than the preset threshold value of the cold water tank level, the output of the working fluid pressurizing pump group (5) is 0; The measured value of the hot water tank level meter (17) is processed by the filter block LEADLAG and used as the switching value after the sum of the output value of the sixth PID controller and the feedforward value of the sixth PID controller. When the measured value of the hot water tank level meter (17) is less than the preset threshold value of the cold water tank level, the output of the working fluid booster pump group (5) is 0; The final outputs of the fifth PID controller and the sixth PID controller are subjected to mode selection by the switching block. When the system is in the heat storage mode, the output of the working fluid pressurizing pump group (5) is the output instruction of the fifth PID controller. When the system is in the heat release mode, the output of the working fluid pressurizing pump group (5) is the output instruction of the sixth PID controller.

9. A hot water storage tank nitrogen constant pressure system control method according to claim 6, characterized in that: The following steps are also included: The cold water tank liquid level control module controls the liquid level of the cold water tank (1). When the water volume in the normal pressure water tank (8) is lower than a preset water volume threshold, the liquid level of the cold water tank (1) is controlled by the working fluid pressure pump (7), the fourth electric shut-off valve (24), the fifth electric shut-off valve (25), and the cold water tank liquid level gauge (23) of the cold water tank liquid level control module. When the pressure of the cold water tank (1) exceeds a preset pressure threshold, the cold water tank liquid level control module releases the pressure.

10. A hot water storage tank nitrogen constant pressure system control method according to claim 6, characterized in that: The control method of the working fluid booster pump (7) is: The measured value of the cold water tank level meter (23) is processed by the filter block LEADLAG and used as the PV value of the PID controller; The liquid level setting value of the cold water tank (1) and the fine-tuning signal are summed to serve as the SP value of the PID controller; The PV value of the PID controller and the SP value of the PID controller are subjected to PID calculation by the PID controller to obtain the output value of the actuator of the working fluid pressure pump (7) for regulating the liquid level of the cold water tank (1) by the cold water tank liquid level control module.

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