A multi-energy complementary phase change heat storage system combined with a three-pipe heating system

Abstract

The application discloses a multi-energy complementary phase change heat storage system combined with a three-pipe heating system, and belongs to the technical field of energy, which comprises a primary network water supply pipeline, a secondary network water supply pipeline and corresponding backwater pipelines, the secondary network water supply pipeline is communicated with an electric air source heat pump, a low-temperature phase change heat storage device, a plate heat exchanger and a high-temperature phase change heat storage device, the primary network water supply pipeline is communicated with the plate heat exchanger and the high-temperature phase change heat storage device, and the plate heat exchanger comprises a first plate heat exchanger and a second plate heat exchanger. The multi-energy complementary phase change heat storage system combined with the three-pipe heating system is clear about the division of labor between the high-temperature and low-temperature heating pipe networks through the three-pipe heating system, the high-temperature heating pipe network is responsible for the radiator system, and the low-temperature heating pipe network is focused on the floor heating system, so that the stability and heating efficiency of the whole system are improved; in the period when the heat supply of a thermal power plant decreases, the system realizes efficient heat supply with electric energy as a driving force, and stable operation of the system is ensured.

Description

Technical Field

[0001] This invention relates to the field of energy technology, and in particular to a multi-energy complementary phase change thermal storage system combined with a three-pipe heating system. Background Technology

[0002] With a high proportion of renewable energy being integrated into urban power grids, the power system faces increasingly significant peak-shaving pressure. In particular, the heat-driven power generation characteristic of combined heat and power (CHP) plants presents challenges during periods of high renewable energy consumption. Due to the instability of renewable energy sources (such as wind and solar power), power system fluctuations frequently occur, especially during peak renewable energy periods. CHP plants may reduce power generation to cope with fluctuations in grid demand. This leads to a decrease in the heat output of CHP plants in the CHP system, creating a heat gap that needs to be filled by other heat sources.

[0003] Based on this, a multi-energy complementary phase change thermal storage system that is combined with a three-pipe heating system is proposed. Summary of the Invention

[0004] The purpose of this invention is to provide a multi-energy complementary phase change thermal storage system that is integrated with a three-pipe heating system. Through the three-pipe heating system, the division of labor between high-temperature and low-temperature heating networks is clearly defined. The high-temperature heating network is mainly responsible for the radiator system, while the low-temperature heating network focuses on the underfloor heating system, thereby improving the stability and heating efficiency of the entire system. During periods when the heating capacity of the power plant decreases, the system uses electricity as the driving force to achieve efficient heating and ensure the stable operation of the system.

[0005] To achieve the above objectives, the present invention provides a multi-energy complementary phase change heat storage system integrated with a three-pipe heating system, comprising a primary network water supply pipeline, a secondary network water supply pipeline, and corresponding return water pipelines. The secondary network water supply pipeline is connected to an electric air source heat pump, a low-temperature phase change heat storage device, a plate heat exchanger, and a high-temperature phase change heat storage device. The primary network water supply pipeline is connected to the plate heat exchanger and the high-temperature phase change heat storage device. The plate heat exchanger includes a first plate heat exchanger and a second plate heat exchanger. The return water pipeline includes a primary network return water pipe and a secondary network return water pipe.

[0006] Preferably, the primary network water supply pipeline is provided with a primary network water supply pipe, and a first primary network shut-off valve is provided on the primary network water supply pipe. The other end of the first primary network shut-off valve is connected to the primary network return water pipe through a first branch, a second branch and a third branch. A second primary network shut-off valve is provided on the primary network return water pipe.

[0007] Preferably, a first primary network regulating valve is provided on the first branch, the end of the first branch is connected to the first plate heat exchanger, and the first plate heat exchanger is connected to the primary network return water pipe.

[0008] A second primary network regulating valve is provided on the second branch, and the end of the second branch is connected to the second plate heat exchanger. The second plate heat exchanger is connected to the primary network return water pipe.

[0009] The third branch is sequentially equipped with a high-temperature phase change heat storage device heat storage regulating valve and a second high-temperature phase change heat storage device heat storage on / off valve. The end of the third branch is connected to the high-temperature phase change heat storage device, and the other end of the high-temperature phase change heat storage device is connected to the primary network return water pipe through the first high-temperature phase change heat storage device heat storage on / off valve.

[0010] Preferably, the secondary network water supply pipeline is connected to the secondary network return water pipeline, and a secondary network circulation pump is installed at the end of the secondary network return water pipeline.

[0011] Preferably, the secondary network circulation pump is connected to the electric air source heat pump in sequence through an electric air source heat pump regulating valve and a first electric air source heat pump on / off valve. The other end of the electric air source heat pump is connected to a second electric air source heat pump on / off valve. The other end of the second electric air source heat pump on / off valve is connected to a low-temperature phase change heat storage device regulating valve, a third electric air source heat pump on / off valve, and a fourth electric air source heat pump on / off valve, respectively.

[0012] The electric air source heat pump includes a condenser and an evaporator. An expansion valve is installed on the input pipe of the evaporator, and a compressor is installed on the output pipe of the evaporator. The electric air source heat pump is connected to other components through the condenser.

[0013] Preferably, the other end of the regulating valve of the low-temperature phase change heat storage device is connected to the low-temperature phase change heat storage device, and the other end of the low-temperature phase change heat storage device is connected to the secondary network circulation pump through the on / off valve of the low-temperature phase change heat storage device.

[0014] The other end of the third electric air source heat pump on / off valve is connected to the secondary network low temperature water supply pipe.

[0015] The other end of the fourth electric air source heat pump on / off valve is connected to the secondary network circulation pump.

[0016] Preferably, the secondary network circulation pump is connected to one end of the high-temperature phase change heat storage device through a first high-temperature phase change heat storage device heating regulating valve and a first high-temperature phase change heat storage device heating on / off valve, and the other end of the high-temperature phase change heat storage device is connected to a second high-temperature phase change heat storage device heating on / off valve and a second high-temperature phase change heat storage device heating regulating valve, respectively.

[0017] Preferably, the other end of the heating on / off valve of the second high-temperature phase change heat storage device is connected to the high-temperature water supply pipe of the secondary network;

[0018] The other end of the heating regulating valve of the second high-temperature phase change heat storage device is connected to the low-temperature water supply pipe of the secondary network through the heating on / off valve of the third high-temperature phase change heat storage device.

[0019] Preferably, the secondary network circulation pump is connected to the first plate heat exchanger through the first plate heat exchanger regulating valve, and the other end of the first plate heat exchanger is connected to the secondary network low-temperature water supply pipe through the first plate heat exchanger on / off valve.

[0020] Preferably, the secondary network circulation pump is connected to the second plate heat exchanger through a regulating valve of the second plate heat exchanger, and the other end of the second plate heat exchanger is connected to the secondary network high-temperature water supply pipe through a shut-off valve of the second plate heat exchanger.

[0021] Therefore, the multi-energy complementary phase change thermal storage system of the present invention, which is combined with a three-pipe heating system, has the following beneficial effects:

[0022] (1) This invention improves the flexibility of the heating system by configuring high-temperature and medium-low temperature phase change heat storage devices and electric air source heat pumps in the heating system and reasonably coordinating the operating status of these devices, so that the system can better respond to changes in heat user demand and fluctuations in energy supply.

[0023] (2) The present invention uses an electric air source heat pump to generate heat and directly supply it to the secondary network. Compared with the water supply temperature of the primary network, the temperature is lower, which can improve the performance of the electric air source heat pump and thus improve the energy utilization efficiency.

[0024] (3) This invention configures both high-temperature and medium-low-temperature phase change heat storage devices in the system, realizing the cascade utilization of energy. The high-temperature phase change heat storage device is highly efficient in storing and releasing heat, and can provide a large amount of heat in a short time, which helps to meet the system's demand for peak heat. From the perspective of system economy, peak and off-peak electricity prices cause the output of electric air source heat pumps to fluctuate. Medium-low-temperature phase change heat storage devices can store low-grade heat energy from electric air source heat pumps, increase the proportion of renewable energy in the heating system, and reduce the system's dependence on traditional energy.

[0025] (4) Phase change thermal storage realizes the storage and release of energy during the phase change process, and has advantages such as higher energy density, better stability and longer storage time. Phase change thermal storage devices can alleviate the mismatch between energy supply and demand in time and space, effectively play the role of peak shaving and valley filling on the load side, and improve the stability and reliability of the system.

[0026] (5) The present invention uses an air source heat pump to generate heat during off-peak electricity periods and stores the excess heat of the system through a phase change heat storage device. The stored heat is released during periods of high energy costs or peak heat load, which can effectively reduce the operating cost of the system.

[0027] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0028] Figure 1 This is a schematic diagram of the structure of an embodiment of the present invention;

[0029] Figure 2 The process of working condition one in this embodiment of the invention Figure 1 ;

[0030] Figure 3 The process of working condition one in this embodiment of the invention Figure 2 ;

[0031] Figure 4 The process of working condition two in this embodiment of the invention Figure 1 ;

[0032] Figure 5 The process of working condition two in this embodiment of the invention Figure 2 ;

[0033] Figure 6 The process of working condition two in this embodiment of the invention Figure 3 ;

[0034] Figure 7 The process of working condition two in this embodiment of the invention Figure 4 ;

[0035] Figure 8 This is a flowchart of working condition three in an embodiment of the present invention;

[0036] Figure label:

[0037] 1. Electric air source heat pump; 1A. Evaporator; 1B. Condenser; 1C. Compressor; 1D. Expansion valve; 2. High-temperature phase change heat storage device; 3. Low-temperature phase change heat storage device; 4. Secondary network circulation pump; 5. First plate heat exchanger; 6. Second plate heat exchanger; 7. First primary network on / off valve; 8. Second primary network on / off valve; 9. First primary network regulating valve; 10. Second primary network regulating valve; 11. First plate heat exchanger regulating valve; 12. First plate heat exchanger on / off valve; 13. Second plate heat exchanger regulating valve; 14. Second plate heat exchanger on / off valve; 15. First high-temperature phase change heat storage device heat storage on / off valve; 16. High-temperature phase change heat storage device heat storage regulating valve. 17. Second high-temperature phase change heat storage device heat storage on / off valve; 18. First high-temperature phase change heat storage device heating regulating valve; 19. First high-temperature phase change heat storage device heating on / off valve; 20. Second high-temperature phase change heat storage device heating on / off valve; 21. Electric air source heat pump regulating valve; 22. First electric air source heat pump on / off valve; 23. Second electric air source heat pump on / off valve; 24. Low-temperature phase change heat storage device regulating valve; 25. Low-temperature phase change heat storage device on / off valve; 26. Third electric air source heat pump on / off valve; 27. Fourth electric air source heat pump on / off valve; 28. Second high-temperature phase change heat storage device heating regulating valve; 29. ​​Third high-temperature phase change heat storage device heating on / off valve. Detailed Implementation

[0038] The technical solution of the present invention will be further described below with reference to the accompanying drawings and embodiments.

[0039] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are some embodiments of the present invention, but not all embodiments.

[0040] The operating mode of the multi-energy complementary phase change thermal storage system combined with a three-pipe heating system according to the present invention is as follows:

[0041] This system can adjust the system operation mode according to the system heat load, primary network operating parameters, operating status of electric air source heat pump 1, electricity price, and operating status of phase change heat storage device;

[0042] This system can adjust the operating parameters of the secondary high-temperature / low-temperature water supply network by adjusting the valve openings of the first adjusting plate heat exchanger regulating valve 12 and the second plate heat exchanger regulating valve 13 according to the heat load of the high-temperature / low-temperature water supply network, the operating parameters of the primary network, the operating status of the air source heat pump and the operating status of the phase change heat storage device.

[0043] The phase change temperature of the material in the high-temperature phase change heat storage device 2 is set between the primary network water supply temperature and the secondary network high-temperature water supply temperature, while the phase change temperature of the material in the low-temperature phase change heat storage device 3 is set between the air source heat pump water supply temperature and the secondary network return water temperature.

[0044] Operating Condition 1:

[0045] This operating condition includes a high-temperature phase change heat storage device 2, a secondary network circulation pump 4, a first plate heat exchanger 5, a second plate heat exchanger 6, pipelines, regulating valves, and on / off valves.

[0046] 1) such as Figure 2 As shown, when the heat supply from the primary network exceeds the system heat load, the excess heat is stored by the high-temperature phase change heat storage device 2. The following valves are activated: secondary network circulation pump 4, first primary network on / off valve 7, second primary network on / off valve 8, first primary network regulating valve 9, second primary network regulating valve 10, first plate heat exchanger regulating valve 11, first plate heat exchanger on / off valve 12, second plate heat exchanger regulating valve 13, second plate heat exchanger on / off valve 14, first high-temperature phase change heat storage device heat storage on / off valve 15, high-temperature phase change heat storage device heat storage regulating valve 16, and second high-temperature phase change heat storage device heat storage on / off valve 17.

[0047] 2) For example Figure 3 As shown, when the primary heat supply cannot meet the system's heat load, the high-temperature phase change heat storage device 2 releases heat. This involves starting the secondary network circulation pump 4, the first primary network on / off valve 7, the second primary network on / off valve 8, the first primary network regulating valve 9, the second primary network regulating valve 10, the first plate heat exchanger regulating valve 11, the first plate heat exchanger on / off valve 12, the second plate heat exchanger regulating valve 13, the second plate heat exchanger on / off valve 14, the first high-temperature phase change heat storage device heating regulating valve 18, the first high-temperature phase change heat storage device heating on / off valve 19, and the second high-temperature phase change heat storage device heating on / off valve 20.

[0048] Operating Condition 2:

[0049] This operating condition includes an electric air source heat pump 1, a high-temperature phase change heat storage device 2, a low-temperature phase change heat storage device 3, a secondary network circulation pump 4, a first plate heat exchanger 5, a second plate heat exchanger 6, pipelines, regulating valves, and on / off valves.

[0050] During off-peak electricity prices, the electric air source heat pump 1 is turned on and the excess heat is stored through the low-temperature phase change heat storage device 3. The stored heat is released during periods of higher energy costs or peak heat load, thereby reducing system operating costs.

[0051] As the condensing temperature of the electric air source heat pump 1 increases, the COP of the heat pump shows a downward trend. Considering economic factors, the system switches the operating mode of the electric air source heat pump 1 based on the primary network operating parameters, the heat storage status of the phase change heat storage device, the user's heat load (high temperature, medium and low temperature heating load size), and electricity prices.

[0052] Operating mode 1: The hot water temperature output by the electric air source heat pump 1 is lower than the low temperature of the secondary network supply water, and the hot water is supplied to the secondary network return water pipe network.

[0053] Operating mode 2: The hot water temperature output by the electric air source heat pump 1 is equal to the low-temperature water supply temperature of the secondary network, and the hot water is directly supplied to the low-temperature water supply network of the secondary network.

[0054] 1) When the power grid is in off-peak electricity price period, and the total heat supply of the primary grid heating and the electric air source heat pump 1 is equal to the system heat load, the electric air source heat pump 1 operates under mode one.

[0055] like Figure 4 As shown, the following valves are activated: secondary network circulation pump 4, first primary network on / off valve 7, second primary network on / off valve 8, first primary network regulating valve 9, second primary network regulating valve 10, first plate heat exchanger regulating valve 11, first plate heat exchanger on / off valve 12, second plate heat exchanger regulating valve 13, second plate heat exchanger on / off valve 14, electric air source heat pump regulating valve 21, first electric air source heat pump on / off valve 22, second electric air source heat pump on / off valve 23, and fourth electric air source heat pump on / off valve 27.

[0056] 2) When the power grid is in off-peak electricity price period, and the total heat supply of the primary grid heating and the electric air source heat pump is greater than the system heat load, the excess heat of the electric air source heat pump is stored by the low temperature phase change heat storage device 3, and the electric air source heat pump operates in mode one.

[0057] like Figure 5 As shown, the following valves are activated: secondary network circulation pump 4, first primary network on / off valve 7, second primary network on / off valve 8, first primary network regulating valve 9, second primary network regulating valve 10, first plate heat exchanger regulating valve 11, first plate heat exchanger on / off valve 12, second plate heat exchanger regulating valve 13, second plate heat exchanger on / off valve 14, electric air source heat pump regulating valve 21, first electric air source heat pump on / off valve 22, second electric air source heat pump on / off valve 23, low temperature phase change heat storage device regulating valve 24, low temperature phase change heat storage device on / off valve 25, and fourth electric air source heat pump on / off valve 27.

[0058] 3) When the power grid is in a peak price period, and the heat supply of the primary grid is less than the system heat load and the low temperature phase change heat storage device 3 has heat stored, the low temperature phase change heat storage device 3 releases heat.

[0059] like Figure 6As shown, the following valves are activated: secondary network circulation pump 4, first primary network on / off valve 7, second primary network on / off valve 8, first primary network regulating valve 9, second primary network regulating valve 10, first plate heat exchanger regulating valve 11, first plate heat exchanger on / off valve 12, second plate heat exchanger regulating valve 13, second plate heat exchanger on / off valve 14, low-temperature phase change heat storage device regulating valve 24, low-temperature phase change heat storage device on / off valve 25, and fourth electric air source heat pump on / off valve 27.

[0060] 4) When the power grid is in off-peak electricity price period, and the primary grid interrupts the heat supply due to faults or maintenance, and the high-temperature phase change heat storage device 2 has heat storage, the electric air source heat pump 1 and the high-temperature phase change heat storage device 2 will provide heat supply. The electric air source heat pump will operate under mode two conditions.

[0061] like Figure 7 As shown, the secondary network circulation pump 4, the first high-temperature phase change heat storage device heating regulating valve 18, the first high-temperature phase change heat storage device heating on / off valve 19, the second high-temperature phase change heat storage device heating on / off valve 20, the electric air source heat pump regulating valve 21, the first electric air source heat pump on / off valve 22, the second electric air source heat pump on / off valve 23, and the third electric air source heat pump on / off valve 26 are turned on.

[0062] Operating Condition 3:

[0063] This operating condition includes high-temperature phase change heat storage device 2, low-temperature phase change heat storage device 3, pipelines and regulating valves.

[0064] When the heat supply of the primary network and electric air source heat pump 1 is interrupted due to fault or maintenance, and the high-temperature phase change heat storage device 2 and the low-temperature phase change heat storage device 3 have heat stored, the high-temperature phase change heat storage device 2 and the low-temperature phase change heat storage device 3 shall provide heat.

[0065] like Figure 8 As shown, the following valves are activated: secondary network circulation pump 4, first high-temperature phase change heat storage device heating regulating valve 18, first high-temperature phase change heat storage device heating on / off valve 19, second high-temperature phase change heat storage device heating on / off valve 20, low-temperature phase change heat storage device regulating valve 24, low-temperature phase change heat storage device on / off valve 25, third electric air source heat pump on / off valve 26, second high-temperature phase change heat storage device heating regulating valve 28, and third high-temperature phase change heat storage device heating on / off valve 29.

[0066] Example

[0067] As shown in Tables 1 and 2 below, determine whether to turn on the air source heat pump based on electricity prices and economic analysis;

[0068] The operating parameters of the secondary high-temperature / low-temperature water supply network are adjusted by adjusting the valve openings of the first plate heat exchanger regulating valve 12 and the second plate heat exchanger regulating valve 14.

[0069] The phase change temperature of the material in the high-temperature phase change heat storage device 2 is set between the primary network water supply temperature and the secondary network high-temperature water supply temperature, and the phase change temperature of the material in the low-temperature phase change heat storage device 3 is set between the air source heat pump water supply temperature and the secondary network return water temperature.

[0070] Table 1. Operating status of equipment under different operating modes

[0071]

[0072] Table 2 Valve operating status under different operating modes

[0073]

[0074] In heating systems, the introduction of phase change thermal storage devices can regulate the return water temperature of both the primary and secondary networks, thereby improving system performance and efficiency. Assume the initial settings are: primary network supply water temperature 90℃, primary network return water temperature 60℃, secondary network high-temperature supply water temperature 70℃, low-temperature supply water temperature 40℃, and secondary network return water temperature 30℃.

[0075] During system operation, when the heat supply from the heat source exceeds the system heat load, the primary network return water temperature will rise. When the primary network return water temperature rises to exceed the preset temperature threshold of 60°C, the phase change heat storage device starts to work. The excess heat of the system is stored by the high-temperature and low-temperature phase change heat storage devices, thereby controlling the primary network return water temperature within a certain range.

[0076] When the user-side load demand suddenly increases, the secondary network water supply temperature will drop. When the secondary network return water temperature drops below the preset temperature threshold of 30°C, the high-temperature or low-temperature phase change heat storage device will release the stored heat to ensure the stable operation of the system.

[0077] By using a phase change heat storage device, the heating system increases the temperature difference between the primary network supply and return water, making the system more flexible and better able to adapt to different load changes.

[0078] Phase change thermal storage devices introduce a unique thermal energy buffering mechanism to the heating system, effectively mitigating the phenomenon of excessive rise in the temperature of the primary network return water, enabling the system to cope with sudden excessive heat source output, and improving the stability of the heating system.

[0079] Utilizing off-peak electricity prices to improve the economic efficiency of this system:

[0080] During off-peak electricity periods, electric air source heat pumps are used to generate heat and supply it directly to the secondary network to improve the economic efficiency of the heating system.

[0081] Assume the off-peak electricity price during the heating season is 0.15 yuan / kWh, the off-peak period is from 1:00 to 6:00, and the heating season is 120 days. An electric air source heat pump is operated during the off-peak electricity period. The electric air source heat pump supplies water at 40℃, has a COP of 3.5, and has a total installed capacity of 500kW.

[0082] Compared to systems using electric boilers as auxiliary heat sources, the annual electricity cost savings are:

[0083]

[0084] Therefore, the present invention provides a multi-energy complementary phase change thermal storage system combined with a three-pipe heating system. Through the three-pipe heating system, the division of labor between high-temperature and low-temperature heating networks is clearly defined. The high-temperature heating network is mainly responsible for the radiator system, while the low-temperature heating network focuses on the underfloor heating system, thereby improving the stability and heating efficiency of the entire system. During periods when the heating supply from the thermal power plant decreases, efficient heating is achieved using electricity as the driving force, ensuring the stable operation of the system.

[0085] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the technical solutions of the present invention, and these modifications or equivalent substitutions cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A multi-energy complementary phase change thermal storage system integrated with a three-pipe heating system, characterized in that: It includes a primary water supply network, a secondary water supply network, and corresponding return water pipelines. The secondary water supply network is connected to an electric air source heat pump, a low-temperature phase change heat storage device, a plate heat exchanger, and a high-temperature phase change heat storage device. The primary water supply network is connected to the plate heat exchanger and the high-temperature phase change heat storage device. The plate heat exchanger includes a first plate heat exchanger and a second plate heat exchanger. The return water pipeline includes a primary network return water pipe and a secondary network return water pipe. A secondary network circulation pump is installed at the end of the secondary network return water pipe. The primary network water supply pipeline is equipped with a primary network water supply pipe, and a first primary network shut-off valve is installed on the primary network water supply pipe. The other end of the first primary network shut-off valve is connected to the primary network return water pipe through a first branch, a second branch and a third branch. A second primary network shut-off valve is installed on the primary network return water pipe. The first branch is equipped with a first primary network regulating valve, the end of the first branch is connected to the first plate heat exchanger, and the first plate heat exchanger is connected to the primary network return water pipe. A second primary network regulating valve is provided on the second branch, and the end of the second branch is connected to the second plate heat exchanger. The second plate heat exchanger is connected to the primary network return water pipe. The third branch is sequentially equipped with a high-temperature phase change heat storage device heat storage regulating valve and a second high-temperature phase change heat storage device heat storage on / off valve. The end of the third branch is connected to the high-temperature phase change heat storage device, and the other end of the high-temperature phase change heat storage device is connected to the primary network return water pipe through the first high-temperature phase change heat storage device heat storage on / off valve. The secondary network circulation pump is connected to one end of the high-temperature phase change heat storage device through the first high-temperature phase change heat storage device heating regulating valve and the first high-temperature phase change heat storage device heating on / off valve. The other end of the high-temperature phase change heat storage device is connected to the second high-temperature phase change heat storage device heating on / off valve and the second high-temperature phase change heat storage device heating regulating valve, respectively. The secondary network circulation pump is connected to the first plate heat exchanger through the regulating valve of the first plate heat exchanger, and the other end of the first plate heat exchanger is connected to the secondary network low temperature water supply pipe through the on / off valve of the first plate heat exchanger. The secondary network circulation pump is connected to the second plate heat exchanger through the regulating valve of the second plate heat exchanger, and the other end of the second plate heat exchanger is connected to the secondary network high temperature water supply pipe through the on / off valve of the second plate heat exchanger. The phase change temperature of the material in the high-temperature phase change heat storage device is set between the primary network water supply temperature and the secondary network high-temperature water supply temperature, while the phase change temperature of the material in the low-temperature phase change heat storage device is set between the air source heat pump water supply temperature and the secondary network return water temperature. The multi-energy complementary phase change thermal storage system shall switch to at least the following operating modes based on the system heat load, the heat supply status of the primary water supply network, and the electricity price status: First mode: When the heat supply of the primary water supply pipeline is greater than the system heat load, the high-temperature phase change heat storage device stores the excess heat; when the heat supply of the primary water supply pipeline is less than the system heat load, the high-temperature phase change heat storage device releases heat. Second mode: During off-peak electricity pricing periods, the electric air source heat pump starts heating. When the total heat supply of the electric air source heat pump and the primary network water supply pipeline is equal to the system heat load, the hot water output by the electric air source heat pump is directly supplied to the secondary network return water pipe. When the total heat supply of the electric air source heat pump and the primary network water supply pipeline is greater than the system heat load, the low-temperature phase change heat storage device stores the excess heat. The third mode: During peak electricity price periods, when the heat supply of the primary network water supply pipeline is less than the system heat load and the low-temperature phase change heat storage device has heat storage, the low-temperature phase change heat storage device releases heat. Fourth mode: When the heat supply from the primary water supply pipeline is interrupted and the high-temperature phase change heat storage device has heat storage, the electric air source heat pump and the high-temperature phase change heat storage device will work together to provide heat.

2. The multi-energy complementary phase change thermal storage system combined with a three-pipe heating system according to claim 1, characterized in that: The secondary water supply pipeline is connected to the secondary water return pipeline.

3. A multi-energy complementary phase change thermal storage system combined with a three-pipe heating system according to claim 2, characterized in that: The secondary network circulation pump is connected to the electric air source heat pump in sequence through an electric air source heat pump regulating valve and a first electric air source heat pump on / off valve. The other end of the electric air source heat pump is connected to a second electric air source heat pump on / off valve. The other end of the second electric air source heat pump on / off valve is connected to a low-temperature phase change heat storage device regulating valve, a third electric air source heat pump on / off valve, and a fourth electric air source heat pump on / off valve, respectively.

4. A multi-energy complementary phase change thermal storage system combined with a three-pipe heating system according to claim 3, characterized in that: The other end of the regulating valve of the low-temperature phase change heat storage device is connected to the low-temperature phase change heat storage device, and the other end of the low-temperature phase change heat storage device is connected to the secondary network circulation pump through the on / off valve of the low-temperature phase change heat storage device. The other end of the third electric air source heat pump on / off valve is connected to the secondary network low temperature water supply pipe. The other end of the fourth electric air source heat pump on / off valve is connected to the secondary network circulation pump.

5. A multi-energy complementary phase change thermal storage system combined with a three-pipe heating system according to claim 4, characterized in that: The other end of the heating on / off valve of the second high-temperature phase change heat storage device is connected to the high-temperature water supply pipe of the secondary network. The other end of the heating regulating valve of the second high-temperature phase change heat storage device is connected to the low-temperature water supply pipe of the secondary network through the heating on / off valve of the third high-temperature phase change heat storage device.

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