Power and heat combined supply system based on graded heat storage, control method and optimization regulation and control method

Abstract

The invention discloses an electricity and heat combined supply system based on graded heat storage, a control method and an optimization regulation and control method. The system comprises a photovoltaic heat module which comprises a photovoltaic assembly used for converting solar energy into electric energy and a heat exchange assembly used for collecting heat generated in the working process of the photovoltaic assembly; the heat storage module is used for storing heat collected by the heat exchange assembly by using a first heat storage box when the temperature of a heat exchange medium at the outlet of the heat exchange assembly is not higher than a first set temperature value, and storing heat collected by the heat exchange assembly by using a second heat storage box when the temperature of the heat exchange medium at the outlet of the heat exchange assembly is higher than the first set temperature value; the second heat storage box is further used for supplying heat to the outside. And the heat pump module is used for absorbing heat from the first heat storage box and transferring the absorbed heat into the second heat storage box, so that the second heat storage box stably supplies heat to the outside. During photovoltaic power generation, heat generated in the power generation process is recycled and stored, the solar energy utilization rate is increased, and heat loss in the utilization process is reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of comprehensive utilization of solar energy, and in particular to a combined heat and electricity supply system based on graded heat storage, a control method and an optimization and regulation method. Background Art

[0002] Solar energy is a clean, renewable and almost inexhaustible energy source. Currently, there are various ways to utilize solar energy. The most common one is photovoltaic power generation, which directly converts sunlight into electrical energy through solar panels. However, the current photoelectric conversion efficiency is about 22%, which means that only 22% of solar radiation energy is converted into electrical energy, and the remaining 78% is converted into thermal energy. This part of thermal energy is not efficiently used for heating or other thermal energy needs, but is lost into the air. Therefore, how to improve the utilization rate of solar energy is an urgent problem to be solved. Summary of the invention

[0003] The problem to be solved by the present invention is to overcome the defects of the prior art and provide a combined heat and power generation system based on graded heat storage, a control method and an optimization and regulation method, which can recover and store the heat generated in the power generation process while generating photovoltaic power, thereby improving the utilization rate of solar energy and reducing heat loss in the process of solar energy utilization.

[0004] To solve the above technical problems, the present invention provides, on one hand, a combined heat and power generation system based on graded heat storage, comprising: a photovoltaic heat module, comprising a photovoltaic component for converting solar energy into electrical energy and a heat exchange component for collecting heat generated during the operation of the photovoltaic component; a heat storage module, used to use a first heat storage tank to store the heat collected by the heat exchange component when the temperature of the heat exchange medium at the outlet of the heat exchange component is not higher than a first set temperature value, and to use a second heat storage tank to store the heat collected by the heat exchange component when the temperature of the heat exchange medium at the outlet of the heat exchange component is higher than the first set temperature value; the second heat storage tank is also used to supply heat to the outside; a heat pump module, used to absorb heat from the first heat storage tank and transfer the absorbed heat to the second heat storage tank.

[0005] In the above-mentioned combined heat and electricity generation system based on graded heat storage, the heat generated by the photovoltaic module can be recovered while the photovoltaic module is generating electricity through the heat exchange component and the heat storage module, thereby improving the utilization rate of solar energy; and the heat storage module grades the recovered heat through the first set temperature value, and uses the first heat storage tank and the second heat storage tank to gradiently recover and store it, thereby realizing graded heat storage and effectively reducing the loss of recovered heat; in addition, the heat pump module can convert the low-grade heat in the first heat storage tank into high-grade heat, which is stored in the second heat storage tank, and finally the second heat storage tank is used to supply heat to the outside, thereby realizing full utilization of the recovered heat, and further solving the problem of low comprehensive utilization rate of solar energy and large loss during utilization. The system can provide high-grade thermal energy within a certain range to the outside, such as buildings, to meet the needs of building hot water, heating or industrial heating. Compared with traditional photovoltaic systems, it can greatly improve the utilization rate of solar energy, and is one of the important solutions to achieve near-zero energy consumption buildings.

[0006] Preferably, the electricity generated by the photovoltaic module can be supplied to the combined heat and power generation system based on graded heat storage, so as to realize self-production and self-use of electricity. Phase change material is arranged in the first heat storage tank to improve the energy storage density.

[0007] As an improvement of the electric heat and power combined supply system based on graded heat storage of the present invention, the heat storage module also includes: a three-way valve A, a first heat exchanger, a second heat exchanger, a three-way valve B, and a first circulation pump connected through a pipeline; the first heat exchanger is used to exchange heat with the first heat storage tank; the second heat exchanger is used to exchange heat with the second heat storage tank; the inlet of the three-way valve A is connected to the heat storage medium outflow outlet of the heat exchange component, one outlet is connected to the inlet of the first heat exchanger, and the other outlet is connected to the inlet of the second heat exchanger; the outlet of the three-way valve B is connected to the inlet of the first circulation pump, one inlet is connected to the outlet of the first heat exchanger, and the other inlet is connected to the outlet of the second heat exchanger; the outlet of the first circulation pump is connected to the heat storage medium reflux port of the heat exchange component.

[0008] The first heat exchanger and the second heat exchanger are arranged in parallel through two three-way valves, so that in the actual process of heat transfer and storage, in the face of constantly fluctuating real-time heat, they can respond quickly and switch working states quickly, storing part of the heat in the first heat storage tank and the other part of the heat with high temperature in the second heat storage tank. The pipeline layout of the entire system is ingenious and reasonable.

[0009] Furthermore, the heat storage module also includes a first control unit, a first temperature sensor, a second temperature sensor and a third temperature sensor, the first temperature sensor is used to obtain the temperature of the heat exchange medium at the outlet of the heat exchange component; the second temperature sensor is used to obtain the temperature of the heat storage medium at the outlet of the first heat storage tank for heat exchange with the heat pump module; the third temperature sensor is used to obtain the temperature of the heat storage medium at the outlet of the second heat storage tank for supplying heat to the outside; the first control unit is used to control the working states of the three-way valve A, the three-way valve B and the first circulation pump according to the temperature values ​​obtained by the first temperature sensor, the second temperature sensor and the third temperature sensor.

[0010] The heat storage process is controlled by the first control unit, and the collected heat is accurately transferred and stored in two gradients according to various temperature sensors.

[0011] Furthermore, the control process of the first control unit includes:

[0012] When T a ≤T0 and T a -T b ≥ΔT1, first control the three-way valve A and the three-way valve B to connect the first heat exchanger and disconnect the second heat exchanger, and then start the first circulation pump until T a >T0 or T a -T b When <ΔT2, the first circulation pump is stopped;

[0013] When T a >T0 and T a -T c ≥ΔT3, first control the three-way valve A and the three-way valve B to disconnect the first heat exchanger and connect the second heat exchanger, and then start the first circulation pump until T a ≤T0 or T a -T b When <ΔT4, the first circulation pump is stopped;

[0014] T a is the temperature of the heat exchange medium at the outlet of the heat exchange component; T b is the temperature of the heat storage medium at the outlet of the first heat storage tank for heat exchange with the heat pump module; T c is the temperature of the heat storage medium at the outlet of the second heat storage tank supplying heat to the outside; T0 is the first set temperature value; ΔT1, ΔT2, ΔT3 and ΔT4 are all given values.

[0015] As another improvement of the electric heat and power combined supply system based on graded heat storage of the present invention, the heat pump module includes a heat pump unit, a second control unit and a third temperature sensor, the third temperature sensor is used to obtain the temperature of the heat storage medium at the heat storage medium flow outlet of the second heat storage tank for supplying heat to the outside; the second control unit is used to control whether the heat pump unit is working according to the temperature value obtained by the third temperature sensor; when the heat pump unit is working, it absorbs heat from the first heat storage tank and transfers the absorbed heat to the second heat storage tank.

[0016] The second control unit controls the heat extraction process of the second heat storage tank from the first heat storage tank, and takes the heating temperature of the second heat storage tank as a reference to ensure that the heat outlet temperature of the second heat storage tank is within a set range, that is, to ensure stable heating.

[0017] Furthermore, the control process of the second control unit includes:

[0018] When T c ≤T1, start the heat pump unit and continue to work until T c When ≥T2, the heat pump unit is stopped;

[0019] Among them, T c is the temperature of the heat storage medium at the outlet of the second heat storage tank supplying heat to the outside; T1 and T2 are both given values.

[0020] The second control unit maintains the temperature of the heat storage medium supplied to the outside by the second heat storage tank within the range of T1-T2, thereby stably supplying heat to the outside. The second heat storage tank stably supplies heat to the outside, which means that the temperature of the heat storage medium at the heat storage medium outflow outlet of the second heat storage tank supplying heat to the outside is maintained within the set temperature range.

[0021] Furthermore, there are multiple heat pump units, and the heat-releasing sides of the evaporators of the multiple heat pump units are connected in series between the heat storage medium inlet and outlet of the first heat storage tank, and the heat-absorbing sides of the condensers of the multiple heat pump units are connected in series between the heat storage medium inlet and outlet of the second heat storage tank, thereby realizing gradient absorption of the heat of the heat storage medium in the first heat storage tank and gradient increase of the temperature of the heat storage medium in the second heat storage tank.

[0022] When the heat pump module is working, by setting up multiple heat pump units in series, the heat gradient recovery and gradient improvement of the heat storage medium in the first heat storage tank can be achieved, and the heat storage medium in the second heat storage tank can be gradient heated, reducing heat loss during heat recovery and transfer.

[0023] Furthermore, the heat storage medium inlet and outlet of the first heat storage tank are connected by pipelines and are provided with: a second circulation pump, a first valve and a heat release side of the evaporators of the plurality of the heat pump units; the second circulation pump is used to drive the heat storage medium in the first heat storage tank to circulate in the pipeline; the first valve is used to control the on-off of the pipeline; and in the pipeline, along the flow direction of the heat storage medium in the first heat storage tank, the operating temperature range of the heat absorption side of the evaporators of the respective heat pump units gradually decreases.

[0024] Furthermore, the second heat storage tank is provided with two groups of heat storage medium inlets and outlets, one group is used for supplying heat to the outside; the heat storage medium inlets and outlets of the other group are connected by pipelines and are provided with: a third circulation pump, a second valve and a heat absorption side of the condensers of the plurality of the heat pump units; the third circulation pump is used to drive the heat storage medium in the second heat storage tank to circulate in the pipeline; the second valve is used to control the on-off of the pipeline; along the flow direction of the heat storage medium in the second heat storage tank, the operating temperature range of the heat release side of the condensers of the respective heat pump units gradually increases.

[0025] In order to solve the above technical problems, the present invention provides, on the other hand, a control method for the above-mentioned combined heat and power generation system based on hierarchical heat storage, comprising:

[0026] When the temperature of the heat exchange medium at the outlet of the heat exchange component is not higher than the first set temperature value, the first heat storage tank is used to store the heat collected by the heat exchange component; when the temperature of the heat exchange medium at the outlet of the heat exchange component is higher than the first set temperature value, the second heat storage tank is used to store the heat collected by the heat exchange component.

[0027] Further, when the temperature of the heat exchange medium at the outlet of the heat exchange component is not higher than the first set temperature value, the first heat storage tank is used to store the heat collected by the heat exchange component; when the temperature of the heat exchange medium at the outlet of the heat exchange component is higher than the first set temperature value, the second heat storage tank is used to store the heat collected by the heat exchange component, including:

[0028] When T a ≤T0 and T a -T b ≥ΔT1, the heat exchange component and the first heat storage tank are allowed to exchange heat;

[0029] When T a >T0 and T a -T c ≥ΔT3, the heat exchange component and the second heat storage tank are allowed to exchange heat;

[0030] Among them, T a is the temperature of the heat exchange medium at the outlet of the heat exchange component; T b is the temperature of the heat storage medium at the outlet of the first heat storage tank for heat exchange with the heat pump module; Tc is the temperature of the heat storage medium at the outlet of the second heat storage tank supplying heat to the outside; T0 is the first set temperature value; ΔT1 and ΔT3 are both given values.

[0031] Preferably, the method for making the heat exchange assembly and the first heat storage tank perform heat exchange includes: first controlling the three-way valve A and the three-way valve B to connect the first heat exchanger and disconnect the second heat exchanger, and then starting the first circulation pump until T a >T0 or T a -T b When ΔT2 is less than ΔT2, the first circulation pump is stopped. ΔT2 is a given value.

[0032] Preferably, the method for making the heat exchange assembly and the second heat storage tank perform heat exchange includes: first controlling the three-way valve A and the three-way valve B to disconnect the first heat exchanger and connect the second heat exchanger, and then starting the first circulation pump until T a ≤T0 or T a -T b When ΔT4 is less than ΔT4, the first circulation pump is stopped. ΔT4 is a given value.

[0033] Furthermore, when T c ≤T1, the heat pump module is started to work until T c ≥T2, the heat pump unit is stopped; wherein, T c is the temperature of the heat storage medium at the outlet of the second heat storage tank supplying heat to the outside; T1 and T2 are both given values.

[0034] In order to solve the above technical problems, the present invention also provides an optimization control method based on the above control method, comprising:

[0035] When the first circulating pump, the second circulating pump and the third circulating pump are actually in operation, the operation state of the hierarchical heat storage combined heat and electricity supply system at the previous moment is simulated and analyzed, and a multi-objective particle swarm optimization algorithm is used to determine the optimal matching flow rates of the first circulating pump, the second circulating pump and the third circulating pump, respectively, with the maximum net power production capacity, the maximum load guarantee rate and the maximum heat collection amount of the hierarchical heat storage combined heat and electricity supply system as the optimization objective function, and the first circulating pump, the second circulating pump and the third circulating pump are controlled and adjusted to actually operate at their respective optimal matching flow rates at the current moment;

[0036] Among them, the heat exchange component drives the internal heat exchange medium to flow through the first circulation pump to achieve heat transfer with the first heat storage tank or the second heat storage tank; the first heat storage tank drives the internal heat storage medium to flow through the second circulation pump to achieve heat transfer with the heat pump module; the second heat storage tank drives the internal heat storage medium to flow through the third circulation pump to achieve heat transfer with the heat pump module.

[0037] Through the coupling of simulation software and optimization algorithm, the optimal matching flow at each moment in the operation process is explored and analyzed, and the circulation pump flow of the graded heat storage combined heat and power generation system is actually optimized and controlled based on the exploration and analysis results, so that the operating performance of the entire system: system heat production, power production, load guarantee rate, etc. are all in the optimal state.

[0038] In summary, the above-mentioned combined heat and power supply system, control method and optimization regulation method based on graded heat storage are adopted to recover and store heat gradients, and realize low-temperature thermal energy gradient extraction and gradient grade improvement through multi-stage heat pump components, so as to effectively reduce heat loss, solve the problems of low comprehensive utilization rate of solar energy and large losses in the utilization process, and have significant energy saving and economy. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] In the attached picture:

[0040] Figure 1 This is a structural diagram of the combined heat and power generation system based on graded heat storage according to the present invention.

[0041] In the figure, 1, photovoltaic component; 21, heat exchange component; 22, first heat storage tank; 23, second heat storage tank; 24, three-way valve A; 25, first heat exchanger; 26, second heat exchanger; 27, three-way valve B; 28, first circulation pump; 31, second circulation pump; 32, first valve; 33, third circulation pump; 34, second valve; 311, first evaporator; 312, first condenser; 313, first compressor; 314, first expansion valve; 321, second evaporator; 322, second condenser; 323, second compressor; 324, second expansion valve; 35, fourth circulation pump; 36, third valve; 37, user end; 41, first temperature sensor; 42, second temperature sensor; 43, third temperature sensor. DETAILED DESCRIPTION

[0042] The specific embodiments of the present invention are further described below in conjunction with the accompanying drawings. It should be noted that the description of these embodiments is used to help understand the present invention, but does not constitute a limitation of the present invention.

[0043] Example 1

[0044] Figure 1The present invention shows a combined heat and power generation system based on graded heat storage, which is used during the day, specifically when there is sunlight. Figure 1 As shown, the combined heat and electricity supply system based on graded heat storage includes a photovoltaic heat module, a heat storage module and a heat pump module. The photovoltaic heat module converts solar energy into electrical energy and thermal energy; then the thermal energy is recovered and stored in two gradients through the thermal storage module, that is, a part of the thermal energy with a low temperature is stored in the first thermal storage tank 22 to form a low-temperature heat source, and a part of the thermal energy with a high temperature is stored in the second thermal storage tank 23 to form a high-temperature heat source. The heat energy in the high-temperature heat source can be used directly, so the second thermal storage tank 23 can directly supply heat to the outside; the heat in the low-temperature heat source needs to be upgraded by the heat pump module before it can be stored in the second thermal storage tank 23, and then used to supply heat to the outside. In short, the entire system recovers and utilizes heat energy while generating photovoltaic power, thereby improving the comprehensive utilization rate of solar energy. In addition, a step-by-step extraction strategy is adopted for heat recovery, which greatly improves the efficiency of heat recovery and reduces heat loss during the recovery process. The heat pump system is used to upgrade the quality of the recovered low-temperature heat energy, which can ultimately provide high-quality heat energy to buildings within a certain range to meet the needs of building hot water, heating or industrial heating, and further solve the problem of low comprehensive utilization rate of solar energy and large losses during the utilization process.

[0045] Photovoltaic thermal modules are similar to conventional photovoltaic thermal systems, usually referred to as PV / T systems. In the process of converting solar energy into electrical energy, photovoltaic cells will generate a certain amount of heat. Traditional photovoltaic power generation systems often only focus on the output of electrical energy and ignore the use of this part of thermal energy. However, in photovoltaic thermal systems, not only does it convert solar energy into electrical energy, but it also collects the generated heat through heat pipes or other heat exchange equipment, lowering the operating temperature of the battery, increasing the service life of the photovoltaic cell, and also realizing the recycling of thermal energy, greatly improving the comprehensive utilization rate of solar energy.

[0046] The photovoltaic heat module of the present invention comprises a photovoltaic component 1 and a heat exchange component 21 . The photovoltaic component 1 is used to convert solar energy into electrical energy; the heat exchange component 21 is used to collect heat generated during the operation of the photovoltaic component 1 .

[0047] Photovoltaic module 1 is a common solar panel, which is the core part of the photovoltaic power generation system. Its main function is to convert solar energy into electrical energy. Photovoltaic module 1 cooperates with other components of the photovoltaic power generation system, such as inverters, energy storage devices such as batteries, photovoltaic brackets, etc., to supply household, commercial and industrial electrical appliances. Of course, the electrical energy generated by photovoltaic module 1 can also be supplied to the combined heat and electricity supply system based on graded heat storage, such as driving various circulation pumps, valves, heat pump components, etc., to improve the energy saving and economy of the entire combined heat and electricity supply system based on graded heat storage.

[0048] The heat exchange component 21 is used to collect the heat generated during the operation of the photovoltaic component 1, that is, it can collect the heat generated by the photovoltaic component 1 in the process of converting solar energy into electrical energy. The structure of the heat exchange component 21 is diverse. For example, it can be a heat pipe structure laid on the back of the photovoltaic component 1. The heat exchange medium inside the heat pipe structure can collect and take away the heat generated by the photovoltaic component. In addition, the heat exchange component 21 is usually filled with a heat exchange medium as a carrier of thermal energy to transfer and exchange heat; it should be noted that: the temperature of the heat exchange medium at the outlet of the heat exchange component 21 refers to the temperature of the heat exchange medium at the heat exchange medium outlet of the heat exchange component 21 when the heat exchange component 21 is transferring heat with the first heat storage tank 22 or the second heat storage tank 23.

[0049] The heat storage module is a heat exchange circuit that can automatically select a heat storage location according to the temperature of the heat exchange medium at the outlet of the heat exchange component 21. First, the heat exchange component 21 is used to exchange heat with the photovoltaic component 1 to collect heat, and then it is determined whether the temperature of the heat exchange medium at the outlet of the heat exchange component 21 is higher than the first set value. If it is higher, it is stored in the second heat storage tank 23, and if it is lower, it is stored in the first heat storage tank 22, so that the heat generated by the photovoltaic component 1 is recovered and stored in two gradients.

[0050] The main reasons for recycling and storing heat in two gradients are as follows: First, two heat storage tanks are arranged in parallel, and heat is recycled in two different temperature ranges, respectively. The temperature range of recycled heat is more precise and extensive, and more heat is finally recycled. Second, due to reasons such as light fluctuations, the heat generated by the photovoltaic module 1 during operation also fluctuates. For example, when the light is strong and the ambient temperature is high, the heat generated by the photovoltaic heat module is more, and the corresponding heat exchange medium temperature is high. These heats are similar to the concept of high-grade heat sources in the heat pump system, and recycling, storage and subsequent use are relatively easy, so they are stored in the second heat storage tank 23 and directly supplied to the outside for heat supply; on the contrary, when the light is weak and the ambient temperature is low, although heat is also generated, the corresponding heat exchange medium temperature is low, and these heats are similar to the concept of low-grade heat sources in the heat pump system, and recycling, storage and subsequent use are relatively difficult, so they need to be recycled and stored in the first heat storage tank 22. The low-grade heat energy in the first heat storage tank 22 needs to be upgraded by the subsequent heat pump module before it can be stored in the second heat storage tank 23 and supplied to the outside.

[0051] The first heat storage tank 22 and the second heat storage tank 23 are conventional heat storage thermal energy structures, such as both are hot water storage tanks. In addition, due to light fluctuations, the heat exchange component 21 usually collects more low-temperature heat than high-temperature heat. In order to improve the heat storage capacity of the first heat storage tank 22, not only is the heat storage medium water filled in the tank, but phase change materials such as low-temperature paraffin are also placed at the bottom of the tank to form a phase change hot water storage tank, thereby improving the energy storage density.

[0052] In order to realize the transfer and storage of heat in two gradients, the heat exchange pipeline is designed as follows Figure 1 As shown, the heat storage module also includes: a three-way valve A24, a first heat exchanger 25, a second heat exchanger 26, a three-way valve B27, and a first circulation pump 28 connected by pipelines. The first heat exchanger 25 is arranged inside the first heat storage tank 22, and is used to exchange heat with the first heat storage tank 22, that is, it can transfer heat to the first heat storage tank 22. The second heat exchanger 26 is arranged inside the second heat storage tank 23, and is used to exchange heat with the second heat storage tank 23, that is, it can transfer heat to the second heat storage tank 23. The inlet of the three-way valve A24 is connected to the heat storage medium outflow port of the heat exchange component 21, one outlet is connected to the inlet of the first heat exchanger 25, and the other outlet is connected to the inlet of the second heat exchanger 26. The outlet of the three-way valve B27 is connected to the inlet of the first circulation pump 28, one inlet is connected to the outlet of the first heat exchanger 25, and the other inlet is connected to the outlet of the second heat exchanger 26. The outlet of the first circulation pump 28 is connected to the heat storage medium return port of the heat exchange component 21.

[0053] The first circulation pump 28 drives the heat exchange medium in the heat exchange assembly 21 to circulate through the first heat exchanger 25 or the second heat exchanger 26, so as to transfer the heat generated by the photovoltaic assembly 1 to the first heat storage tank 22 or the second heat storage tank 23. In addition, the three-way valve A24 and the three-way valve B27 can control the on-off of the parallel pipe branch where the first heat exchanger 25 and the second heat exchanger 26 are located, so as to switch the first heat storage tank 22 and the second heat storage tank 23 when storing heat, so as to store heat in two gradients. In addition, the heat exchange medium in the heat exchange assembly 21 is also water.

[0054] In order to realize the transfer and storage of heat in two gradients, the corresponding control design is as follows: Figure 1 As shown, the heat storage module also includes a first control unit, a first temperature sensor 41, a second temperature sensor 42 and a third temperature sensor 43. The first temperature sensor 41 is used to obtain the temperature of the heat exchange medium at the outlet of the heat exchange component 21; the second temperature sensor 42 is used to obtain the temperature of the heat storage medium at the outlet of the first heat storage tank 22 for heat exchange with the heat pump module; the third temperature sensor 43 is used to obtain the temperature of the heat storage medium at the outlet of the second heat storage tank 23 for supplying heat to the outside; the first control unit is used to control the working states of the three-way valve A24, the three-way valve B27 and the first circulation pump 28 according to the temperature values ​​obtained by the first temperature sensor 41, the second temperature sensor 42 and the third temperature sensor 43.

[0055] For the convenience of description, let’s record: T a is the temperature of the heat exchange medium at the outlet of the heat exchange component 21; T b T is the temperature of the heat storage medium at the outlet of the first heat storage tank 22 for heat exchange with the heat pump module; cis the temperature of the heat storage medium at the outlet of the second heat storage tank 23 supplying heat to the outside; T0 is the first set temperature value; ΔT1, ΔT2, ΔT3 and ΔT4 are all given values.

[0056] The first control unit is the control brain of the heat storage module. Through three temperature sensors, if the outlet temperature of the heat exchange component 21 is T a >T0, at which point the outlet fluid temperature is high enough to be used directly for heating, so it is directly fed into the heat exchange coil in the second heat storage tank 23 connected to the user side. a ≤T0, at this time, the outlet temperature is lower than the heating temperature, and the energy grade needs to be improved by the heat pump system, so the heat exchange coil in the first thermal storage tank 22 is passed to transfer the heat to the fluid in the tank. Finally, part of the heat generated by the photovoltaic thermal module is stored in the first thermal storage tank 22, and the other part with high temperature is stored in the second thermal storage tank 23, so that the heat generated by the photovoltaic thermal module is transferred and stored in two gradients. The specific control process of the first control unit includes the following two situations ①②.

[0057] ①When T a ≤T0 and T a -T b ≥ΔT1, first control the three-way valve A24 and the three-way valve B27 to connect the first heat exchanger 25 and disconnect the second heat exchanger 26, and then start the first circulation pump 28 until T a >T0 or T a -T b When <ΔT2, the first circulation pump 28 is stopped.

[0058] When T a ≤T0, it is determined that the first heat storage tank 22 needs to be used to store the heat collected by the heat exchange component 21, that is, the first heat exchanger 25 works and the second heat exchanger 26 does not work. At this time, it is also necessary to determine whether the first heat storage tank 22 can receive a temperature of T a The heat carried by the heat exchange medium is only a In order to achieve heat exchange, the higher the temperature difference, the better the heat exchange effect.

[0059] The real-time temperature in the first heat storage tank 22 may be uneven, so the output port of the first heat storage tank 22 is used as an approximate reference, that is, the temperature T of the heat storage medium at the outlet of the first heat storage tank 22 for heat exchange with the heat pump module is b Approximately replace the real-time temperature in the first heat storage tank 22, so the following conditions must be met: T a -T b ≥ΔT1, the first heat storage tank 22 can be used to store heat; until the above two conditions change and T a >T0 or T a -Tb Stop when ΔT1 is a given temperature difference, usually about 3°C; ΔT2 is a given temperature difference, usually about 1°C, and the T0 value range is usually 45-55°C, with the best being 50°C.

[0060] The specific execution process is: control the three-way valve A24 and the three-way valve B27, and start the first circulation pump 28, so that the heat exchange medium in the heat exchange component 21 flows through the three-way valve A24, the first heat exchanger 25, the three-way valve B27, the first circulation pump 28 in sequence, and finally returns to the heat exchange component 21, and the real-time collected heat is transferred through the first heat exchanger 25 and stored in the first heat storage tank 22; until T a >T0 and T a -T b When one of the conditions in <ΔT2 is satisfied, the first circulation pump 28 is stopped, and the heat collected in real time is stopped from being transferred through the first heat exchanger 25 and stored in the first heat storage tank 22.

[0061] ②When T a >T0 and T a -T c ≥ΔT3, first control the three-way valve A24 and the three-way valve B27 to disconnect the first heat exchanger 25 and connect the second heat exchanger 26, and then start the first circulation pump 28 until T a ≤T0 or T a -T b When <ΔT4, the first circulation pump 28 is stopped.

[0062] When T a >T0 When the condition is met, it is determined that the second heat storage tank 23 needs to be used to store the heat collected by the heat exchange component 21, that is, the first heat exchanger 25 does not work and the second heat exchanger 26 works. At this time, it is also necessary to determine whether the second heat storage tank 23 can receive the heat with a temperature of T a The heat carried by the heat exchange medium is only a In order to achieve heat exchange, the higher the temperature difference, the better the heat exchange effect.

[0063] The real-time temperature in the second heat storage tank 23 may be uneven, so the heat output port of the second heat storage tank 23 for external heat supply is used as an approximate reference, that is, the heat storage medium temperature T at the outlet of the second heat storage tank 23 for external heat supply is c Approximately replace the real-time temperature in the second heat storage tank 23, so the following conditions must be met: T a -T c ≥ΔT3, the second heat storage tank 23 can be used to store heat until the above two conditions change and T a ≤T0 or T a -T bStop when ΔT4 is less than ΔT3. ΔT3 is a given temperature difference, usually around 3°C; ΔT 34 For a given temperature difference, usually around 1°C.

[0064] The specific execution process is: when T a >T0 and T a -T c When the condition ≥ΔT3 is met, the three-way valve A24 and the three-way valve B27 are controlled, and the first circulation pump 28 is started, so that the heat exchange medium in the heat exchange component 21 flows through the three-way valve A24, the second heat exchanger 26, the three-way valve B27, the first circulation pump 28 in sequence, and finally returns to the heat exchange component 21, and the heat collected in real time is transferred through the second heat exchanger 26 and stored in the second heat storage tank 23; until T a ≤T0 and T a -T b When one of the conditions in <ΔT4 is satisfied, the first circulation pump 28 is stopped, and the heat collected in real time is stopped from being transferred through the second heat exchanger 26 and stored in the second heat storage tank 23 .

[0065] In addition, it should be noted that when the above two situations are not met, the three-way valve A24 and the three-way valve B27 are both in the closed position, that is, the first circulation pump 28 and the first heat exchanger 25 are working and the second heat exchanger 26 is not working.

[0066] In order to utilize the heat stored in the first heat storage tank 22, the heat pump module includes a heat pump unit, a second control unit and a third temperature sensor 43. The third temperature sensor 43 is used to obtain the temperature of the heat storage medium at the heat storage medium flow outlet of the second heat storage tank 23 for supplying heat to the outside; the second control unit is used to control whether the heat pump unit is working according to the temperature value obtained by the third temperature sensor 43; when the heat pump unit is working, it absorbs heat from the first heat storage tank 22 and transfers the absorbed heat to the second heat storage tank 23, so as to supply heat to the outside and utilize the heat stored in the first heat storage tank 22.

[0067] The specific control process of the second control unit includes: c ≤T1, start the heat pump unit and wait until T c When ≥T2, the heat pump unit stops working. c is the temperature of the heat storage medium at the outlet of the second heat storage tank 23 supplying heat to the outside; T1 and T2 are both given values. T1 and T2 are used for heat control, T1 is the minimum water supply temperature, usually in the range of 40-50°C, and the best is 45°C; T2 is the maximum heating temperature, usually in the range of 51-60°C, and the best is 55°C. That is, the outlet temperature T of the second heat storage tank 23 c ≤T1, the heat pump unit needs to be started to heat the water in the tank until the outlet temperature of the second heat storage tank 23 is T cWhen ≥T2, the heat pump unit stops running to keep the temperature in the second heat storage tank 23 stable within the set range, that is, stably supply heat to the outside.

[0068] Heat pump is a common energy-saving device. Its core function is to transfer heat energy from low-temperature heat source to high-temperature heat source, so as to achieve efficient use of energy. Most of its application scenarios are to use low-grade heat energy in natural air, water or soil, and provide people with usable high-grade heat energy after electricity works. The heat pump unit of the present invention has the same technical structure and function as conventional heat pump.

[0069] In order to fully absorb the heat in the first heat storage tank 22 and fully transfer the absorbed heat to the second heat storage tank 23, there are multiple heat pump units, and the evaporator heating sides of the multiple heat pump units are connected in series between the heat storage medium inlet and outlet of the first heat storage tank 22, and the condenser heat absorption sides of the multiple heat pump units are connected in series between the heat storage medium inlet and outlet of the second heat storage tank 23, thereby achieving gradient absorption of the heat of the heat storage medium in the first heat storage tank 22 and gradient increase of the heat storage medium temperature in the second heat storage tank 23.

[0070] Specifically, the heat storage medium inlet and outlet of the first heat storage tank 22 are connected by pipelines and are provided with: a second circulation pump 31, a first valve 32 and the heat release side of the evaporators of multiple heat pump units; the second circulation pump 31 is used to drive the heat storage medium in the first heat storage tank 22 to circulate in the pipeline; the first valve 32 is used to control the on-off of the pipeline; in the pipeline, along the flow direction of the heat storage medium in the first heat storage tank 22, the operating temperature range of the heat absorption side of the evaporator of each heat pump unit gradually decreases.

[0071] like Figure 1 As shown, taking the arrangement structure with two heat pump units as an example, the pipeline connection structure is: the inlet of the second circulation pump 31 is connected to the heat storage medium outlet of the first heat storage tank 22, the outlet of the second circulation pump 31 is connected to the inlet of the first valve 32, the outlet of the first valve 32 is connected to the inlet of the heat release side of the first evaporator 311, the outlet of the heat release side of the first evaporator 311 is connected to the inlet of the heat release side of the second evaporator 321, and the outlet of the heat release side of the second evaporator 321 is connected to the heat storage medium inlet of the first heat storage tank 22.

[0072] Specifically, two groups of heat storage medium inlets and outlets are provided on the second heat storage tank 23, one group is used to supply heat to the outside; the heat storage medium inlet and outlet of the other group are connected by pipelines and are provided with: a third circulation pump 33, a second valve 34 and the condenser heat absorption side of multiple heat pump units; the third circulation pump 33 is used to drive the heat storage medium in the second heat storage tank 23 to circulate in the pipeline; the second valve 34 is used to control the on-off of the pipeline; along the flow direction of the heat storage medium in the second heat storage tank 23, the operating temperature range of the heat release side of the condenser of each heat pump unit gradually increases.

[0073] like Figure 1 As shown, taking the arrangement structure with two heat pump units as an example, the pipeline connection structure is: the heat storage medium outlet of the second heat storage tank 23 is connected to the heat absorption side inlet of the second condenser 322, the heat absorption side outlet of the second condenser 322 is connected to the heat absorption side inlet of the first condenser 312, the heat absorption side outlet of the first condenser 312 is connected to the inlet of the second valve 34, the outlet of the second valve 34 is connected to the inlet of the third circulation pump 33, and the outlet of the third circulation pump 33 is connected to the heat storage medium inlet of the second heat storage tank 23.

[0074] In addition, the second heat storage tank 23 is provided with a heat storage medium inlet and outlet for supplying heat to the outside, and a fourth circulation pump 35, a third valve 36 and a user end 37 are connected through a pipeline. The fourth circulation pump 35 drives the heat storage medium in the second heat storage tank 23 to flow in the pipeline, circulate through the user end 37, and supply heat to the user end. The third valve 36 is used to control the on-off of the pipeline. A first compressor 313 and a first expansion valve 314 are also provided between the first evaporator 311 and the first condenser 312, forming a heat pump unit. Similarly, a second compressor 323 and a second expansion valve 324 are also provided between the second evaporator 321 and the second condenser 322, forming a second heat pump unit.

[0075] The evaporators and condensers of each heat pump unit have different operating temperature ranges, thereby achieving gradient heat absorption and gradient heating. The above two heat pump unit structures are taken as examples as follows: the inlet temperature of the heat release side of the first evaporator 311 is about 25°C, and the outlet is about 20°C; the inlet temperature of the heat release side of the second evaporator 321 is about 20°C, and the outlet is about 15°C; the outlet temperature of the heat absorption side of the first condenser 312 is about 55°C, and the inlet temperature is about 50°C; the outlet temperature of the heat absorption side condenser of the second condenser 322 is about 50°C, and the inlet temperature is about 45°C.

[0076] It should be noted that the heat release side of the evaporator of the heat pump unit of the present invention refers to the side where the external heat source supplies heat, and the heat absorption side refers to the side where the heat pump working fluid absorbs heat by evaporation; the heat release side of the condenser refers to the side where the heat pump condenses and releases heat, and the heat absorption side refers to the side where heat is taken from the outside.

[0077] In order to simplify the control structure, the first control unit and the second control unit may be integrated into one control module, such as one controller.

[0078] Example 2

[0079] The present invention provides a control method for the above-mentioned electric heat combined supply system based on graded heat storage, including: when the temperature of the heat exchange medium at the outlet of the heat exchange component 21 is not higher than the first set temperature value, the first heat storage tank 22 is used to store the heat collected by the heat exchange component 21; when the temperature of the heat exchange medium at the outlet of the heat exchange component 21 is higher than the first set temperature value, the second heat storage tank 23 is used to store the heat collected by the heat exchange component 21. There are two specific implementation situations:

[0080] ①When T a ≤T0 and T a -T b When ΔT1 or greater, the heat exchange component 21 exchanges heat with the first heat storage tank 22 , and the collected heat is stored in the first heat storage tank 22 .

[0081] ②When T a >T0 and T a -T c When ΔT3 or higher, the heat exchange component 21 exchanges heat with the second heat storage tank 23 , and the collected heat is stored in the second heat storage tank 23 .

[0082] For the convenience of description, let’s record: T a is the temperature of the heat exchange medium at the outlet of the heat exchange component 21; T b T is the temperature of the heat storage medium at the outlet of the first heat storage tank 22 for heat exchange with the heat pump module; c is the temperature of the heat storage medium at the outlet of the second heat storage tank 23 supplying heat to the outside; T0 is the first set temperature value; ΔT1, ΔT2, ΔT3 and ΔT4 are all given values; the values ​​of T0, ΔT1, ΔT2, ΔT3 and ΔT4 refer to the description in the above embodiment 1.

[0083] Optionally, the method for making the heat exchange assembly 21 and the first heat storage tank 22 perform heat exchange includes: first controlling the three-way valve A24 and the three-way valve B27 to connect the first heat exchanger 25 and disconnect the second heat exchanger 26, and then starting the first circulation pump 28 until T a >T0 or T a -T b When <ΔT2, the first circulation pump 28 is stopped.

[0084] Optionally, the method for making the heat exchange assembly 21 and the second heat storage tank 23 perform heat exchange includes: first controlling the three-way valve A24 and the three-way valve B27 to disconnect the first heat exchanger 25 and connect the second heat exchanger 26, and then starting the first circulation pump 28 until T a ≤T0 or T a -T b When <ΔT4, the first circulation pump 28 is stopped.

[0085] Optional, when T c≤T1, start the heat pump module and wait until T c ≥T2, the heat pump unit stops working; where T c It is the temperature of the heat storage medium at the outlet of the second heat storage tank 23 supplying heat to the outside; T1 and T2 are both given values.

[0086] In summary, the control strategy of the combined heat and power generation system based on hierarchical heat storage during heat storage is as follows:

[0087] ①When T a Lower than the user-set temperature T0 and higher than T b When the temperature difference ΔT1 is set, the three-way valve A24 and the three-way valve B27 are controlled, and the first circulation pump 28 is started, so that the heat exchange medium in the heat exchange component 21 flows through the three-way valve A24, the first heat exchanger 25, the three-way valve B27, the first circulation pump 28 in sequence, and finally returns to the heat exchange component 21, and the heat collected in real time is transferred through the first heat exchanger 25 and stored in the first heat storage tank 22; until T a >T0 and T a -T b When one of the conditions in <ΔT2 is satisfied, the first circulation pump 28 is stopped, and the heat collected in real time is stopped from being transferred through the first heat exchanger 25 and stored in the first heat storage tank 22.

[0088] ②When T a Higher than the user-set temperature T0 and higher than T c When the temperature difference ΔT3 is set, the three-way valve A24 and the three-way valve B27 are controlled to operate, and the first circulation pump 28 is started, so that the heat exchange medium in the heat exchange component 21 flows through the three-way valve A24, the second heat exchanger 26, the three-way valve B27, the first circulation pump 28 in sequence, and finally returns to the heat exchange component 21, and the heat collected in real time is transferred through the second heat exchanger 26 and stored in the first heat storage tank 22; until T a ≤T0 and T a -T b When one of the conditions in <ΔT4 is satisfied, the first circulation pump 28 is stopped, and the heat collected in real time is stopped from being transferred through the second heat exchanger 26 and stored in the first heat storage tank 22.

[0089] ③ When the above two conditions are not met, the first circulation pump 28 and the first heat exchanger 25 work and the second heat exchanger 26 does not work.

[0090] The heating strategy of the combined heat and power generation system based on hierarchical heat storage includes: when T c ≤T1, the heat pump units are started, each heat pump unit is started, and the temperature of the heat storage medium in the second heat storage tank 23 is increased until T cWhen the temperature is greater than or equal to T2, the heat pump unit stops working. In this way, the temperature of the heat storage medium in the second heat storage tank 23 drops and stabilizes within the set range T1-T2, maintaining a stable heat supply to the outside.

[0091] Example 3

[0092] The present invention provides an optimization control method based on the above control method, comprising:

[0093] When the first circulation pump 28, the second circulation pump 31 and the third circulation pump 33 are actually in operation, the operation state of the hierarchical heat storage combined heat and electricity supply system at the previous moment is simulated and analyzed, and a multi-objective particle swarm optimization algorithm is used to determine the optimal matching flow rates of the first circulation pump 28, the second circulation pump 31 and the third circulation pump 33, respectively, with the maximum net power capacity, the maximum load guarantee rate and the maximum heat collection amount of the hierarchical heat storage combined heat and electricity supply system as the optimization objective function, and the first circulation pump 28, the second circulation pump 31 and the third circulation pump 33 are controlled and adjusted to actually operate at their respective optimal matching flow rates at the current moment;

[0094] Among them, the heat exchange component 21 drives the internal heat exchange medium to flow through the first circulation pump 28 to achieve heat transfer with the first heat storage tank 22 or the second heat storage tank 23; the first heat storage tank 22 drives the internal heat storage medium to flow through the second circulation pump 31 to achieve heat transfer with the heat pump module; the second heat storage tank 23 drives the internal heat storage medium to flow through the third circulation pump 33 to achieve heat transfer with the heat pump module.

[0095] In the electric heat and power generation system with graded heat storage, the flow rate of the first circulating pump 28 affects the inlet and outlet water temperature and thermoelectric efficiency of the heat exchange component 21. Too small a flow rate will cause the inlet and outlet water temperature to rise, reducing the heat transfer efficiency and photoelectric efficiency. Too large a flow rate will cause the inlet and outlet water temperature to decrease, the energy grade to decrease, and the subsequent energy consumption of the heat pump component to increase. The flow rate of the second circulating pump 31 affects the inlet and outlet water temperature of the evaporator heating side of the heat pump component, and the flow rate of the third circulating pump 33 affects the inlet and outlet water temperature of the condenser heat absorption measurement of the heat pump component. The flow rate of the fourth circulating pump 35 affects the temperature of the second heating tank 23, thereby causing the change of the inlet water temperature on the load side of the heat pump component. Therefore, the optimization control method of the present invention assumes that the second heat storage tank 23 stably supplies heat to the outside, that is, the flow rate of the fourth circulating pump 35 is fixed. Based on the system operation data at the previous moment, the coupling of simulation software and optimization algorithm is used to explore and analyze the best matching flow rates of the first circulating pump 28, the second circulating pump 31 and the third circulating pump 33 during the current moment of operation.

[0096] First, a simulation model of the hierarchical heat storage combined heat and power generation system is established to simulate the operation of the system. TRNSYS (Transient System Simulation Tool) can be used. TRNSYS is a transient system simulation program that can be used to study the transient operation of energy systems. In addition, the simulation model includes weather data, such as solar irradiance, dry bulb temperature, wind speed, etc.

[0097] Secondly, establish each objective function. Defining the optimization objective function is the most important part of the optimization problem. In this study, three objective functions are optimized, namely: maximum net power capacity (real time), maximum load guarantee rate (real time) and maximum heat collection (real time).

[0098] (1) The objective function for maximizing the net electricity capacity is:

[0099]

[0100] Among them, t0 is the optimization time, that is, the previous time. To optimize the net power capacity of the system at the moment, in kWh; The power consumption of the system at the time of optimization, in kWh, including the total energy consumption of all heat pump components E hp-t0 And the total energy consumption of all pumps E pumps-t0 ; It is the photovoltaic power generation at the time of system optimization, in kWh.

[0101] (2) The objective function for maximizing the load assurance rate is:

[0102]

[0103] in, In order to optimize the ratio of the total heat production of all heat pump components in the system to the real-time load on the demand side, the demand side is the user end 37; Q hp-t0 The total heat output of all heat pump components in the system at the time of optimization, in kWh; Q load-t0 The real-time load on the demand side at the optimization moment, in kWh.

[0104] (3) The objective function for maximizing the heat collection is:

[0105] Q pv-t0 =c*m*(T p -T q )

[0106] Where Q pv-t0 To optimize the real-time heat collection of the heat exchange component 21 at the moment; c represents the specific heat capacity of the heat exchange medium at constant pressure, if the heat exchange medium is water, it is 4.2 kJ / (kg·℃); m represents the heat exchange medium flow rate, kg / hr; Tp , T q They respectively represent the outlet and inlet working medium temperatures of the heat exchange component 21.

[0107] Next, establish the constraints. The constraints of this system are: the heat pump COP is higher than the user-specified value, and the load guarantee rate is higher than the user-specified value. For example, you can set: the heat pump COP is higher than 4, and the load guarantee rate is higher than 1.

[0108] The heat pump COP (Coefficient of Performance) refers to the ratio of the total heat output of all heat pump components in the system to the power consumption during operation at the optimal time. The calculation formula is:

[0109]

[0110] The optimization control method requires that each pump: the first circulation pump 28, the second circulation pump 31 and the third circulation pump 33 are all flow-adjustable pumps, such as variable frequency pumps, and a flow monitoring sensor is provided at the outlet of each pump for real-time flow monitoring.

[0111] Finally, the operating status data of the combined heat and electricity supply system with graded heat storage at the previous moment is imported into the simulation model. The operating status includes: real-time weather data, outlet temperature of the first heat storage tank 22 and the second heat storage tank 23, load data of the user end 23, etc. The optimization scheme obtained by simulation analysis transmits the signal to each pump through the data transmission module, controls the flow of each pump based on the optimization scheme, and controls and adjusts the first circulation pump 28, the second circulation pump 31 and the third circulation pump 33 to actually operate at their respective preferred matching flow rates at the current moment. In this way, the multi-objective optimization algorithm is combined with the combined heat and electricity supply system based on graded heat storage, and the flow of each variable frequency water pump at each moment is optimized according to the given objective function and constraints, and the variable frequency command is issued to change the real-time flow of each water pump, and the system performance is optimized at each moment, while ensuring the stability of the system heating, taking into account energy saving and economy, bringing new ideas to the system energy-saving optimization control.

[0112] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit its protection scope. Although the present invention has been described in detail with reference to the above embodiments, ordinary technicians in the field should understand that after reading the present invention, those skilled in the art can still make various changes, modifications or equivalent substitutions to the specific implementation methods of the invention, but these changes, modifications or equivalent substitutions are all within the protection scope of the pending claims of the invention.

Claims

1. A combined heat and power generation system based on hierarchical heat storage, characterized in that: include: A photovoltaic heat module, comprising a photovoltaic component (1) for converting solar energy into electrical energy and a heat exchange component (21) for collecting heat generated during the operation of the photovoltaic component (1); A heat storage module, used for storing heat collected by the heat exchange component (21) using a first heat storage tank (22) when the temperature of the heat exchange medium at the outlet of the heat exchange component (21) is not higher than a first set temperature value, and for storing heat collected by the heat exchange component (21) using a second heat storage tank (23) when the temperature of the heat exchange medium at the outlet of the heat exchange component (21) is higher than the first set temperature value; the second heat storage tank (23) is also used for supplying heat to the outside; The heat pump module is used to absorb heat from the first heat storage tank (22) and transfer the absorbed heat to the second heat storage tank (23).

2. The combined heat and power generation system based on hierarchical heat storage according to claim 1 is characterized in that: The heat storage module further includes: a three-way valve A (24), a first heat exchanger (25), a second heat exchanger (26), a three-way valve B (27), and a first circulation pump (28) connected through pipelines; The first heat exchanger (25) is used to exchange heat with the first heat storage tank (22); the second heat exchanger (26) is used to exchange heat with the second heat storage tank (23); The inlet of the three-way valve A (24) is connected to the heat storage medium outlet of the heat exchange component (21), one outlet is connected to the inlet of the first heat exchanger (25), and the other outlet is connected to the inlet of the second heat exchanger (26); The outlet of the three-way valve B (27) is connected to the inlet of the first circulation pump (28), one inlet is connected to the outlet of the first heat exchanger (25), and the other inlet is connected to the outlet of the second heat exchanger (26); The outlet of the first circulation pump (28) is connected to the heat storage medium return port of the heat exchange component (21).

3. The combined heat and power generation system based on hierarchical heat storage according to claim 2 is characterized in that: The heat storage module further comprises a first control unit, a first temperature sensor (41), a second temperature sensor (42) and a third temperature sensor (43); the first temperature sensor (41) is used to obtain the temperature of the heat exchange medium at the outlet of the heat exchange component (21); the second temperature sensor (42) is used to obtain the temperature of the heat storage medium at the outlet of the first heat storage tank (22) for heat exchange with the heat pump module; the third temperature sensor (43) is used to obtain the temperature of the heat storage medium at the outlet of the second heat storage tank (23) for supplying heat to the outside; The first control unit is used to control the working states of the three-way valve A (24), the three-way valve B (27) and the first circulation pump (28) according to the temperature values ​​obtained by the first temperature sensor (41), the second temperature sensor (42) and the third temperature sensor (43).

4. The combined heat and power generation system based on hierarchical heat storage according to claim 3 is characterized in that: The control process of the first control unit includes: When T a ≤T0 and T a -T b ≥ΔT1, first control the three-way valve A (24) and the three-way valve B (27) to connect the first heat exchanger (25) and disconnect the second heat exchanger (26), and then start the first circulation pump (28) until T a >T0 or T a -T b When <ΔT2, the first circulation pump (28) is stopped; When T a >T0 and T a -T c ≥ΔT3, first control the three-way valve A (24) and the three-way valve B (27) to disconnect the first heat exchanger (25) and connect the second heat exchanger (26), and then start the first circulation pump (28) until T a ≤T0 or T a -T b When ΔT4 is less than, the first circulation pump (28) is stopped; T a is the temperature of the heat exchange medium at the outlet of the heat exchange component (21); T b is the temperature of the heat storage medium at the outlet of the first heat storage tank (22) for heat exchange with the heat pump module; T c is the temperature of the heat storage medium at the outlet of the second heat storage tank (23) supplying heat to the outside; T0 is the first set temperature value; ΔT1, ΔT2, ΔT3 and ΔT4 are all given values.

5. The combined heat and power generation system based on hierarchical heat storage according to claim 1 is characterized in that: The heat pump module comprises a heat pump unit, a second control unit and a third temperature sensor (43); the third temperature sensor (43) is used to obtain the temperature of the heat storage medium at the heat storage medium outflow outlet of the second heat storage tank (23) for supplying heat to the outside; the second control unit is used to control whether the heat pump unit is working according to the temperature value obtained by the third temperature sensor (43); when the heat pump unit is working, it absorbs heat from the first heat storage tank (22) and transfers the absorbed heat to the second heat storage tank (23).

6. The combined heat and power generation system based on hierarchical heat storage according to claim 5, characterized in that: The control process of the second control unit includes: When T c ≤T1, start the heat pump unit and continue to work until T c When ≥T2, the heat pump unit is stopped; Among them, T c is the temperature of the heat storage medium at the outlet of the second heat storage tank (23) supplying heat to the outside; T1 and T2 are both given values.

7. The combined heat and power generation system based on hierarchical heat storage according to claim 5, characterized in that: There are a plurality of heat pump units, and the heat release sides of the evaporators of the plurality of heat pump units are connected in series between the heat storage medium inlet and outlet of the first heat storage tank (22), and the heat absorption sides of the condensers of the plurality of heat pump units are connected in series between the heat storage medium inlet and outlet of the second heat storage tank (23), thereby achieving gradient absorption of heat of the heat storage medium in the first heat storage tank (22) and gradient increase of the temperature of the heat storage medium in the second heat storage tank (23).

8. The combined heat and power generation system based on hierarchical heat storage according to claim 7, characterized in that: The heat storage medium inlet and outlet of the first heat storage tank (22) are connected by pipelines to: a second circulation pump (31), a first valve (32) and the heat release side of the evaporators of the plurality of heat pump units; the second circulation pump (31) is used to drive the heat storage medium in the first heat storage tank (22) to circulate in the pipeline; the first valve (32) is used to control the on-off of the pipeline; and along the flow direction of the heat storage medium in the first heat storage tank (22) in the pipeline, the operating temperature range of the heat absorption side of the evaporators of the respective heat pump units gradually decreases.

9. The combined heat and power generation system based on hierarchical heat storage according to claim 7, characterized in that: The second heat storage tank (23) is provided with two groups of heat storage medium inlets and outlets, one group being used for supplying heat to the outside; the heat storage medium inlets and outlets of the other group are connected by pipelines and are provided with: a third circulation pump (33), a second valve (34) and a plurality of condenser heat absorption sides of the heat pump units; the third circulation pump (33) is used to drive the heat storage medium in the second heat storage tank (23) to circulate in the pipeline; the second valve (34) is used to control the on-off of the pipeline; along the flow direction of the heat storage medium in the second heat storage tank (23), the operating temperature range of the heat release side of the condenser of each heat pump unit gradually increases.

10. A control method for a combined heat and power generation system based on hierarchical heat storage according to any one of claims 1 to 9, characterized in that: include: When the temperature of the heat exchange medium at the outlet of the heat exchange component (21) is not higher than a first set temperature value, the first heat storage tank (22) is used to store the heat collected by the heat exchange component (21); when the temperature of the heat exchange medium at the outlet of the heat exchange component (21) is higher than the first set temperature value, the second heat storage tank (23) is used to store the heat collected by the heat exchange component (21).

11. A control method according to claim 10, characterized in that: When the temperature of the heat exchange medium at the outlet of the heat exchange component (21) is not higher than the first set temperature value, the first heat storage tank (22) is used to store the heat collected by the heat exchange component (21); when the temperature of the heat exchange medium at the outlet of the heat exchange component (21) is higher than the first set temperature value, the second heat storage tank (23) is used to store the heat collected by the heat exchange component (21) comprises: When T a ≤T0 and T a -T b ≥ΔT1, the heat exchange component (21) and the first heat storage tank (22) are caused to exchange heat; When T a >T0 and T a -T c When ≥ΔT3, the heat exchange component (21) and the second heat storage tank (23) are caused to exchange heat; Among them, T a is the temperature of the heat exchange medium at the outlet of the heat exchange component (21); T b is the temperature of the heat storage medium at the outlet of the first heat storage tank (22) for heat exchange with the heat pump module; T c is the temperature of the heat storage medium at the outlet of the second heat storage tank (23) supplying heat to the outside; T0 is the first set temperature value; ΔT1 and ΔT3 are both given values.

12. A control method according to claim 10, characterized in that: Also includes: When T c ≤T1, the heat pump module is started to work until T c When ≥T2, the heat pump unit is stopped; Among them, T c is the temperature of the heat storage medium at the outlet of the second heat storage tank (23) supplying heat to the outside; T1 and T2 are both given values.

13. An optimization control method based on the control method according to any one of claims 10 to 12, characterized in that: include: When the first circulation pump (28), the second circulation pump (31) and the third circulation pump (33) are actually in operation, the operation state of the hierarchical heat storage combined heat and electricity supply system at the previous moment is simulated and analyzed, and a multi-objective particle swarm optimization algorithm is used to determine the optimal matching flow rates of the first circulation pump (28), the second circulation pump (31) and the third circulation pump (33) respectively, with the maximum net power production capacity, the maximum load guarantee rate and the maximum heat collection amount of the hierarchical heat storage combined heat and electricity supply system as the optimization objective function, and the first circulation pump (28), the second circulation pump (31) and the third circulation pump (33) are controlled and adjusted at the current moment to actually operate at their respective optimal matching flow rates; The heat exchange component (21) drives the internal heat exchange medium to flow through a first circulation pump (28) to achieve heat transfer with the first heat storage tank (22) or the second heat storage tank (23); the first heat storage tank (22) drives the internal heat storage medium to flow through a second circulation pump (31) to achieve heat transfer with the heat pump module; the second heat storage tank (23) drives the internal heat storage medium to flow through a third circulation pump (33) to achieve heat transfer with the heat pump module.

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