Natural gas pressure energy and light storage combined electric energy-cold energy comprehensive utilization system

Abstract

The invention discloses a natural gas pressure energy and light storage combined electric energy-cold energy comprehensive utilization system. Relates to the natural gas industrial energy-saving field. Output circuits of a pressure energy power generation unit, a photovoltaic power generation unit, an energy storage unit and a thermoelectric power generation unit in the system are connected in parallel to a direct current bus; electric energy generated by each unit can be supplied to a direct-current load in a station through a direct-current bus, can be supplied to an alternating-current load in the station through a DC / AC (Direct Current / Alternating Current), and can also be transmitted to a power grid through a power transformer in a grid-connected manner; cold energy generated by the natural gas pressure energy power generation unit in the power generation process is recycled through the temperature difference power generation unit and the circulating cold source; the controller can carry out system layer electric energy-cold energy comprehensive management and equipment layer coordination control. A photovoltaic system is constructed based on existing resources of the station to output photovoltaic electric energy, and meanwhile, fluctuation new energy regulation is carried out by fusing stored energy, so that a green and efficient electric energy-cold energy comprehensive utilization system scheme of gas-light storage linkage in the station is formed.

Description

Technical Field

[0001] The present invention belongs to the technical field of natural gas industry energy conservation, and in particular to the technical field of combined comprehensive utilization of natural gas pressure energy and photovoltaic storage. Background Art

[0002] As natural gas production increases year by year, long-distance transportation of natural gas mainly adopts high-pressure pipeline transportation. Before being transported from the high-pressure pipeline to the low-pressure end-user, it must be subjected to multi-stage pressure reduction treatment at the natural gas stations along the route. The process of natural gas pressure reduction contains huge pressure energy. However, at this stage, the residual pressure resources of natural gas in engineering are still greatly wasted. Especially in the context of the dual carbon goals, the traditional natural gas industry urgently needs to carry out the rational development and utilization of the pressure energy of pipeline natural gas. On the other hand, the production and operation of natural gas stations are also accompanied by a large amount of electricity consumption and cold energy demand such as equipment cooling and refrigeration. With the increase in natural gas production, the demand for electricity and cold energy in the stations will also increase year by year. In addition, natural gas stations are often located in remote areas and the power supply network is relatively weak. How to combine the existing resources of the stations to alleviate the pressure of energy supply is also a key issue that needs to be solved urgently. There are generally available idle land and building roofs in natural gas stations. While considering the optimization of the use of natural gas pressure energy, integrating photovoltaic energy storage and power generation technology is conducive to the realization of green and sustainable development in traditional natural gas stations. Conventional pressure energy utilization schemes are mainly based on single-stage and multi-stage expansion power generation. Electricity and cold energy will be generated simultaneously during the expansion and depressurization process. Existing schemes still have technical problems such as insufficient cold energy utilization and low efficiency of comprehensive utilization of pressure energy. The cascade utilization of cold energy will be an effective means of coping. At the same time, existing research rarely integrates new energy technologies such as photovoltaics and energy storage to conduct comprehensive application research on electricity-cold energy. Based on this, it is necessary to combine existing resources in natural gas stations to build a green, low-carbon, and efficient multi-energy comprehensive utilization system solution. Summary of the invention

[0003] In order to solve the above problems, the present invention provides an electric energy-cold energy comprehensive utilization system combining natural gas pressure energy with photovoltaic storage, which can effectively and fully utilize the natural gas pressure energy for pressure difference power generation and refrigeration, and the generated cold energy is utilized in multiple stages through temperature difference power generation and the cold energy circulation network in the station. A photovoltaic power generation system is constructed based on the available idle land and building roofs in the station to output photovoltaic electricity, and at the same time, energy storage is integrated to adjust the energy of fluctuating new energy.

[0004] In order to achieve the above-mentioned invention object, the technical solution adopted by the present invention is: a natural gas pressure energy and photovoltaic storage combined electric energy-cold energy comprehensive utilization system, including a natural gas pressure energy power generation unit PEU, a photovoltaic power generation unit PVU, an energy storage unit ESU, a thermoelectric power generation unit TEU, a three-phase DC / AC converter DA, a power transformer PT, a controller CC, a circulating cold source CCS, a DC bus DCB, and an AC bus ACB; the output circuits of the natural gas pressure energy power generation unit PEU, the photovoltaic power generation unit PVU, the thermoelectric power generation unit TEU and the energy storage unit ESU are connected in parallel to the DC bus DCB; the electric energy generated by each power generation unit can supply power to the DC load DCL in the station through the DC bus DCB, and can also be supplied through the three-phase DC / AC converter DA is converted into three-phase AC power; the DC side of the three-phase DC / AC converter DA is connected to the DC bus DCB circuit, and the AC side is connected to the AC bus ACB circuit. The converted electric energy supplies power to the AC load ACL in the station, and can be connected to the grid UG through the power transformer PT; the cold energy generated by the natural gas pressure energy generation unit PEU in the power generation process will be recycled and utilized through the temperature difference power generation unit TEU and the circulating cold source CCS. The refrigerant medium in the circulating cold source CCS will pass through the cold energy circulation pipeline in the station to provide cold energy for the DC load DCL and AC load ACL in the station that need to be cooled; the controller CC is connected to each electrical unit in a two-way communication manner, which can realize the comprehensive management of electric energy and cold energy at the system level and coordinated control at the equipment level.

[0005] The natural gas pressure energy power generation unit PEU includes a pressure difference power generation device PED and an AC / DC converter AD PE The pressure difference power generation device PED will generate electricity and cold energy during operation. The power output end of the pressure difference power generation device PED is connected to the AC / DC converter AD PE The AC end of the AC / DC converter AD PE The DC end of the power plant is connected in parallel to the DC bus DCB, and the cold energy generated by the pressure difference power generation device PED exchanges heat with the cold energy circulation network in the station through the natural gas pipeline network; the temperature difference power generation unit TEU includes a temperature difference power generation device TED and a DC / DC converter DD TE The temperature difference power generation device TED can interact with the cold energy circulation network in the station to form the temperature difference for the operation of the internal temperature difference power generation semiconductor. The power output end of the temperature difference power generation device TED is connected to the DC / DC converter DD TE The DC input terminal of the DC / DC converter DD PE The DC output end is connected in parallel to the DC bus DCB; the photovoltaic power generation unit PVU includes a photovoltaic array PVM and a DC / DC converter DD PV , Photovoltaic array PVM and DC / DC converter DD PVThe DC input terminal of the DC / DC converter DD PV The DC output end is connected in parallel to the DC bus DCB; the energy storage unit ESU includes an energy storage device ESD and a bidirectional DC / DC converter DD ES , Energy Storage Device ESD and Bidirectional DC / DC Converter DD ES The DC input terminal is connected to the bidirectional DC / DC converter DD ES The DC output end is connected in parallel to the DC bus DCB, and the energy storage unit ESU can achieve balanced adjustment of electric energy and suppress the random fluctuations of voltage difference electric energy and photovoltaic electric energy.

[0006] The natural gas pipeline equipped with a traditional pressure regulating device TPD is called pipeline branch 1, and a parallel pipeline is led out between the high-pressure natural gas pipeline inlet and the low-pressure natural gas pipeline outlet of pipeline branch 1, which is called pipeline branch 2. The pipeline branch 2 is respectively equipped with an inlet data monitoring unit DMU3, a pressure difference power generation device PED, a temperature difference power generation device TED, a multi-channel flow heat exchanger HEU, and an outlet data monitoring unit DMU4; the inlet data monitoring unit DMU3 can adjust the inlet flow and pressure and monitor the physical quantities such as the inlet natural gas temperature and abnormal state; the pressure difference power generation device PED is connected to the inlet data monitoring unit DMU3, and the high-pressure natural gas can generate electricity and cold energy at the same time after passing through the pressure difference power generation device PED, and the power output port is connected to AD PE The temperature difference power generation device TED is connected to the pressure difference power generation device PED through a natural gas pipeline, and there is cold energy exchange with the pressure difference power generation device PED, and the power output port is connected to DD TE ; After the multi-channel flow heat exchanger HEU is connected to the temperature difference power generation device TED through the natural gas pipeline, it can recover the cold energy that is not fully utilized in the previous stage. The cooled refrigerant is circulated to the cooling circuits in the DC load DCL and the AC load ACL in the station through the circulating cold source CCS, and is used to cool the production equipment; the low-temperature and low-pressure natural gas after the multi-channel flow heat exchanger HEU is connected to the low-pressure natural gas pipeline outlet on the first branch of the pipeline network through the export data monitoring unit DMU4; the export data monitoring unit DMU4 can monitor physical quantities such as export temperature, flow, pressure, and abnormal status.

[0007] The pressure difference power generation device PED includes an expander EM and a coaxially connected generator G; the temperature difference power generation device includes a heat exchanger THE and a temperature difference power generation semiconductor TEG; in the single-stage expansion pressure difference power generation refrigeration and temperature difference power generation utilization form, the pressure difference power generation device PED, the temperature difference power generation device TED and the multi-channel flow heat exchanger HEU can form a gas-electricity-cold modular unit; the pipeline inlet is connected to the expander EM air inlet port, the expander EM air outlet port is connected to the heat exchanger THE inlet, and the generator G coaxially connected to the expander EM is connected to the AC / DC converter AD PE To transmit electric energy, high-pressure natural gas is output as low-temperature and low-pressure natural gas after the action of the expander EM; the low-temperature and low-pressure natural gas can form a temperature difference between the hot and cold sides of the thermoelectric semiconductor TEG after passing through the heat exchanger THE to generate electricity. The circuit output port of the thermoelectric semiconductor TEG is connected to the DC / DC converter DD TE The output port of the heat exchanger THE is then connected to the multi-channel flow heat exchanger HEU in the circulating cold source CCS network, and the refrigerant in the circulating cold source CCS network is used to ensure that the cooling energy of the expanded natural gas is fully utilized; the natural gas heated to a reasonable temperature range is then output through pipelines.

[0008] The pressure difference power generation device PED adopts a single-stage expansion pressure difference power generation, refrigeration and temperature difference power generation utilization form or a multi-stage expansion pressure difference power generation, refrigeration and temperature difference power generation utilization form; the multi-stage expansion pressure difference power generation, refrigeration and temperature difference power generation utilization form cascades the gas-electricity-cold modular units, which can be suitable for the scene with a high pressure difference ratio of the natural gas pipeline network; the high-pressure natural gas is transported to the inlet port of the expander EM1 of the first-stage gas-electricity-cold modular unit, and after the first-stage expansion power generation and cold energy utilization inside the module, it is output by the first-stage multi-channel flow heat exchanger HEU1; the output port of the first-stage multi-channel flow heat exchanger HEU1 is connected to the inlet port of the expander EM2 of the second-stage gas-electricity-cold modular unit, and after the second-stage expansion power generation and cold energy utilization inside the module, the high-pressure natural gas is output by the first-stage multi-channel flow heat exchanger HEU1. After the expansion power and cold energy are utilized, they are output by the second-stage multi-channel flow heat exchanger HEU2; according to the actual pressure and temperature of the output natural gas, it is cascaded to the nth-stage gas-electricity-cold modular unit, and then the natural gas that meets the pressure and temperature range is output and converged through pipelines; the power output ports of the generators in the gas-electricity-cold modular units at each level are output separately or led out to the AC bus for convergence according to actual conditions; the power output ports of the temperature difference power generation semiconductors in the gas-electricity-cold modular units at each level are output separately or led out to the DC bus for convergence according to actual conditions; the multi-channel flow heat exchangers in the gas-electricity-cold modular units at each level are connected to the circulating cold source CCS in the station, giving priority to the cooling service in the station.

[0009] In addition to adopting the single-stage expansion pressure difference power generation, refrigeration and temperature difference power generation utilization form or the parallel multiple expansion pressure difference power generation, refrigeration and temperature difference power generation utilization form, it can be applied to the scene with high pressure difference ratio and large flow of natural gas pipeline network; the multiple expansion pressure difference power generation, refrigeration and temperature difference power generation utilization form multiplexes the gas-electricity-cold modular units in parallel, and the parallel number is the corresponding number of shunt branches; each shunt branch is flow-regulated by a branch shunt valve DV, and the branch shunt valve DV is connected between the pipeline inlet and the air inlet port of each branch expander; the generator power output port and the temperature difference power generation semiconductor power output port in each shunt branch are output separately according to actual conditions, or the AC and DC busbars are led out for power conversion; the multi-channel flow heat exchanger in each shunt branch is connected to the circulating cold source CCS in the station, and the cooling service in the station is given priority; the shunt branch 1, shunt branch 2, ..., shunt branch n in the multiple structure are backup for each other, and the system can perform fault-tolerant control operation.

[0010] The form of electric energy utilization in the electric energy-cold energy comprehensive utilization system combining natural gas pressure energy with photovoltaic storage is to select a self-generation and self-use mode or a self-generation and self-use surplus grid-connected mode according to the total annual power generation of the system and the total annual power consumption of AC and DC loads in the station; if the total annual power generation is greater than the total annual power consumption, the self-generation and self-use surplus grid-connected mode is preferentially adopted; if the total annual power generation is less than or equal to the total annual power consumption, the self-generation and self-use mode is preferentially adopted.

[0011] The beneficial effects of adopting this technical solution are:

[0012] (1) The present invention can fully utilize the pressure energy of natural gas for pressure difference power generation and refrigeration without affecting the normal operation of existing equipment in the natural gas station and the operating parameters such as the outlet pressure, temperature, and flow rate of the pipeline natural gas. The generated cold energy is used in multiple stages through temperature difference power generation and the cold energy circulation network in the station, which can effectively avoid the waste of the pressure energy of the pipeline natural gas and improve the comprehensive utilization efficiency of energy;

[0013] (2) The present invention can combine the available idle land and building roofs in the natural gas station to build a photovoltaic power generation system to output photovoltaic power, and at the same time connect to energy storage to balance the internal power of the system, suppress the random fluctuations of pressure difference, photovoltaic and temperature difference power, and form a green low-carbon electric energy-cold energy comprehensive utilization system solution with gas-photovoltaic-storage linkage through multi-state energy integration in the natural gas station, which can directly supply electric energy and cold energy to the AC and DC loads in the station, and can also be connected to the grid for operation;

[0014] (3) The present invention is applicable to a variety of natural gas application scenarios. According to the on-site conditions, a single-stage expansion pressure difference power generation and refrigeration and temperature difference power generation can be adaptively selected. It can also adopt a series multi-stage or parallel multiple expansion pressure difference power generation and refrigeration and temperature difference power generation. At the same time, the shunt branches in the multiple structure serve as backup for each other, which can perform fault-tolerant operation and control within the system. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 This is a schematic diagram of the structure of a comprehensive utilization system of electric energy and cold energy combining natural gas pressure energy with photovoltaic storage according to the present invention;

[0016] Figure 2 This is a schematic structural diagram of a scheme for comprehensive utilization of the pressure energy of pipeline natural gas in an embodiment of the present invention;

[0017] Figure 3 It is a schematic diagram of a single-stage expansion pressure difference power generation refrigeration and temperature difference power generation utilization in an embodiment of the present invention;

[0018] Figure 4 It is a schematic diagram of an independent multi-stage expansion pressure difference power generation refrigeration and temperature difference power generation utilization in an embodiment of the present invention;

[0019] Figure 5 It is a schematic diagram of a converging multi-stage expansion pressure difference power generation refrigeration and temperature difference power generation utilization in an embodiment of the present invention;

[0020] Figure 6 It is a schematic diagram of an independent multiple expansion pressure difference power generation refrigeration and temperature difference power generation utilization in an embodiment of the present invention;

[0021] Figure 7 It is a schematic diagram of a converging type multiple expansion pressure difference power generation refrigeration and temperature difference power generation utilization in an embodiment of the present invention. DETAILED DESCRIPTION

[0022] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field based on the principles of the present invention without making creative work are within the scope of protection of the present invention.

[0023] In this embodiment, see Figure 1As shown, a natural gas pressure energy and photovoltaic storage combined electric energy-cold energy comprehensive utilization system of the present invention includes a natural gas pressure energy power generation unit PEU, a photovoltaic power generation unit PVU, an energy storage unit ESU, a temperature difference power generation unit TEU, a three-phase DC / AC converter DA, a power transformer PT, a controller CC, a circulating cold source CCS, a DC bus DCB, and an AC bus ACB; the output circuits of the natural gas pressure energy power generation unit PEU, the photovoltaic power generation unit PVU, the temperature difference power generation unit TEU and the energy storage unit ESU are connected in parallel to the DC bus DCB; the electric energy generated by each power generation unit can supply power to the DC load DCL in the station through the DC bus DCB, and can also be converted into a three-phase DC / AC converter DA through a three-phase DC / AC converter DA. AC power; the DC side of the three-phase DC / AC converter DA is connected to the DC bus DCB circuit, and the AC side is connected to the AC bus ACB circuit. The converted electric energy supplies power to the AC load ACL in the station, and can be connected to the grid UG through the power transformer PT; the cold energy generated by the natural gas pressure energy generation unit PEU in the power generation process will be recycled through the temperature difference power generation unit TEU and the circulating cold source CCS. The cold medium in the circulating cold source CCS will pass through the cold energy circulation pipeline in the station to provide cold energy for the DC load DCL and AC load ACL in the station that need to be cooled; the controller CC has a two-way communication connection with each electrical unit, which can realize the comprehensive management of electric energy and cold energy at the system level and coordinated control at the equipment level.

[0024] As an optimization solution of the above embodiment, the natural gas pressure energy power generation unit PEU includes a pressure difference power generation device PED and an AC / DC converter AD PE The pressure difference power generation device PED will generate electricity and cold energy during operation. The power output end of the pressure difference power generation device PED is connected to the AC / DC converter AD PE The AC end of the AC / DC converter AD PE The DC end of the power plant is connected in parallel to the DC bus DCB, and the cold energy generated by the pressure difference power generation device PED exchanges heat with the cold energy circulation network in the station through the natural gas pipeline network; the temperature difference power generation unit TEU includes a temperature difference power generation device TED and a DC / DC converter DD TE The temperature difference power generation device TED can interact with the cold energy circulation network in the station to form the temperature difference for the operation of the internal temperature difference power generation semiconductor. The power output end of the temperature difference power generation device TED is connected to the DC / DC converter DD TE The DC input terminal of the DC / DC converter DD PE The DC output end is connected in parallel to the DC bus DCB; the photovoltaic power generation unit PVU includes a photovoltaic array PVM and a DC / DC converter DD PV , Photovoltaic array PVM and DC / DC converter DD PVThe DC input terminal of the DC / DC converter DD PV The DC output end is connected in parallel to the DC bus DCB; the energy storage unit ESU includes an energy storage device ESD and a bidirectional DC / DC converter DD ES , Energy Storage Device ESD and Bidirectional DC / DC Converter DD ES The DC input terminal is connected to the bidirectional DC / DC converter DD ES The DC output end is connected in parallel to the DC bus DCB, and the energy storage unit ESU can achieve balanced adjustment of electric energy and suppress the random fluctuations of voltage difference electric energy and photovoltaic electric energy.

[0025] As an optimization solution of the above embodiment, see Figure 2 As shown, it is a schematic diagram of the structure of a comprehensive utilization scheme of pipeline natural gas pressure energy in an embodiment of the present invention. On the pipeline branch one where the traditional pressure regulating device TPD is located, a parallel pipeline branch two is led out between the high-pressure natural gas pipeline inlet and the low-pressure natural gas pipeline outlet of the pipeline branch one, and the parallel pipeline branch two includes an inlet data monitoring unit DMU3, a pressure difference power generation device PED, a temperature difference power generation device TED, a multi-channel flow heat exchanger HEU, and an outlet data monitoring unit DMU4; the inlet data monitoring unit DMU3 can regulate the inlet flow and pressure and monitor the physical quantities such as the inlet natural gas temperature and abnormal state; the pressure difference power generation device PED is connected to the inlet data monitoring unit DMU3, and the high-pressure natural gas can generate electricity and cold energy at the same time after passing through the pressure difference power generation device PED, and the power output port is connected to AD PE The temperature difference power generation device TED is connected to the pressure difference power generation device PED through a natural gas pipeline, and there is cold energy exchange between the pressure difference power generation device PED and the power output port is connected to DD TE ; After the multi-channel flow heat exchanger HEU is connected to the temperature difference power generation device TED through the natural gas pipeline, it can recover the cold energy that is not fully utilized in the previous stage. The cooled refrigerant is circulated to the cooling circuits in the DC load DCL and the AC load ACL in the station through the circulating cold source CCS, and is used to cool the production equipment; the low-temperature and low-pressure natural gas after the multi-channel flow heat exchanger HEU is connected to the low-pressure natural gas pipeline outlet on the first branch of the pipeline network through the export data monitoring unit DMU4; the export data monitoring unit DMU4 can monitor physical quantities such as export temperature, flow, pressure, and abnormal status.

[0026] As an optimization solution of the above embodiment, see Figure 3As shown, a single-stage expansion pressure difference power generation refrigeration and temperature difference power generation utilization form in an embodiment of the present invention, the pressure difference power generation device PED includes an expander EM and a coaxially connected generator G; the temperature difference power generation device includes a heat exchanger THE and a temperature difference power generation semiconductor TEG; in the single-stage expansion pressure difference power generation refrigeration and temperature difference power generation utilization form, the pressure difference power generation device PED, the temperature difference power generation device TED and the multi-channel flow heat exchanger HEU can form a gas-electricity-cold modular unit; the pipeline inlet is connected to the expander EM air inlet port, the expander EM air outlet port is connected to the heat exchanger THE inlet, and the generator G coaxially connected to the expander EM is connected to the AC / DC converter AD PE To transmit electric energy, high-pressure natural gas is output as low-temperature and low-pressure natural gas after the action of the expander EM; the low-temperature and low-pressure natural gas can form a temperature difference between the hot and cold sides of the thermoelectric semiconductor TEG after passing through the heat exchanger THE to generate electricity. The circuit output port of the thermoelectric semiconductor TEG is connected to the DC / DC converter DD TE The output port of the heat exchanger THE is then connected to the multi-channel flow heat exchanger HEU in the circulating cold source CCS network, and the refrigerant in the circulating cold source CCS network is used to ensure that the cooling energy of the expanded natural gas is fully utilized; the natural gas heated to a reasonable temperature range is then output through pipelines.

[0027] As an optimization solution of the above embodiment, see Figure 4 and Figure 5 As shown, an independent and convergent multi-stage expansion pressure difference power generation refrigeration and temperature difference power generation utilization form in the embodiment of the present invention is a cascade of the gas-electricity-cold modular units, which can be applicable to high pressure difference ratio natural gas pipeline scenarios; high-pressure natural gas is transported to the inlet port of the expander EM1 of the first-stage gas-electricity-cold modular unit, and after the first-stage expansion power generation and cold energy utilization inside the module, it is output by the first-stage multi-channel flow heat exchanger HEU1; the output port of the first-stage multi-channel flow heat exchanger HEU1 is connected to the inlet port of the expander EM2 of the second-stage gas-electricity-cold modular unit, and after the second-stage expansion power generation and cold energy utilization inside the module, it is output by the second-stage multi-channel flow heat exchanger HEU2; according to the actual pressure and temperature of the output natural gas, it is cascaded to the nth-stage gas-electricity-cold modular unit, and then the natural gas that meets the pressure and temperature range is output and converged through the pipeline; the power output ports of the generators in the gas-electricity-cold modular units at each stage are output separately according to the actual situation, such as Figure 4 As shown, or the AC bus is led out for converging, such as Figure 5 As shown; the power output ports of the temperature difference power generation semiconductors in each level of the gas-electricity-cooling modular unit are output separately according to the actual situation, such as Figure 4 As shown, or the DC bus is led out for converging, such as Figure 5As shown; the multi-channel flow heat exchangers in each level of gas-electricity-cold modular units are all connected to the circulating cold source CCS in the station, giving priority to the cooling service in the station.

[0028] As an optimization solution of the above embodiment, see Figure 6 and Figure 7 As shown, an independent and convergent multiple expansion pressure difference power generation refrigeration and temperature difference power generation utilization form in the embodiment of the present invention can be applied to high pressure difference ratio and large flow natural gas pipeline scene; the multiple expansion pressure difference power generation refrigeration and temperature difference power generation utilization form multiplexes the gas-electricity-cold modular units in parallel, and the parallel number is the corresponding number of shunt branches; each shunt branch is flow-regulated by a branch shunt valve DV, and the branch shunt valve DV is connected between the pipeline inlet and the air inlet port of each branch expander; the generator power output port and the temperature difference power generation semiconductor power output port in each shunt branch are output separately according to actual conditions, or are led out to the AC and DC bus convergence and then power conversion is performed; the multi-channel flow heat exchanger in each shunt branch is connected to the circulating cold source CCS in the station, and the cooling service in the station is given priority; the shunt branch 1, shunt branch 2, ..., shunt branch n in the multiple structure are standby for each other, and the system can perform fault-tolerant control operation.

[0029] As an optimization solution of the above embodiment, in addition to the photovoltaic power generation unit, other new energy power generation units may be externally connected to the DC bus DCB.

[0030] As an optimization scheme for the above-mentioned embodiment, the form of electric energy utilization in the electric energy-cold energy comprehensive utilization system combining natural gas pressure energy with photovoltaic storage selects the self-generation and self-use mode or the self-generation and self-use surplus grid-connected mode according to the total annual power generation of the system and the total annual power consumption of AC and DC loads in the station; if the total annual power generation is greater than the total annual power consumption, the self-generation and self-use surplus grid-connected mode is preferentially adopted; if the total annual power generation is less than or equal to the total annual power consumption, the self-generation and self-use mode is preferentially adopted.

Claims

1. A natural gas pressure energy and photovoltaic storage combined electric energy-cold energy comprehensive utilization system, comprising a natural gas pressure energy power generation unit PEU, a photovoltaic power generation unit PVU, an energy storage unit ESU, a temperature difference power generation unit TEU, a three-phase DC / AC converter DA, a power transformer PT, a controller CC, a circulating cold source CCS, a DC bus DCB, and an AC bus ACB; characterized in that: The output circuits of the natural gas pressure energy power generation unit PEU, the photovoltaic power generation unit PVU, the temperature difference power generation unit TEU and the energy storage unit ESU are connected in parallel to the DC bus DCB; the electric energy generated by each power generation unit can supply power to the DC load DCL in the station through the DC bus DCB, and can be converted into three-phase AC power through the three-phase DC / AC converter DA; the DC side of the three-phase DC / AC converter DA is connected to the DC bus DCB circuit, and the AC side is connected to the AC bus ACB circuit. The converted electric energy supplies power to the AC load ACL in the station, and can be connected to the grid UG through the power transformer PT; The cold energy generated by the natural gas pressure energy power generation unit PEU during the power generation process will be recovered and utilized through the temperature difference power generation unit TEU and the circulating cold source CCS. The refrigerant medium in the circulating cold source CCS will pass through the cold energy circulation pipeline in the station to provide cold energy for the DC load DCL and AC load ACL in the station that need to be cooled. The controller CC has a two-way communication connection with each electrical unit, which can realize the comprehensive management of electric energy and cold energy at the system level and coordinated control at the equipment level.

2. According to claim 1, a natural gas pressure energy and photovoltaic storage combined electric energy-cold energy comprehensive utilization system is characterized in that: The natural gas pressure energy power generation unit PEU includes a pressure difference power generation device PED and an AC / DC converter AD PE The pressure difference power generation device PED will generate electricity and cold energy during operation. The power output end of the pressure difference power generation device PED is connected to the AC / DC converter AD PE The AC end of the AC / DC converter AD PE The DC end of the power plant is connected in parallel to the DC bus DCB, and the cold energy generated by the pressure difference power generation device PED exchanges heat with the cold energy circulation network in the station through the natural gas pipeline network; the temperature difference power generation unit TEU includes a temperature difference power generation device TED and a DC / DC converter DD TE The temperature difference power generation device TED can interact with the cold energy circulation network in the station to form the temperature difference for the operation of the internal temperature difference power generation semiconductor. The power output end of the temperature difference power generation device TED is connected to the DC / DC converter DD TE The DC input terminal of the DC / DC converter DD PE The DC output end is connected in parallel to the DC bus DCB; the photovoltaic power generation unit PVU includes a photovoltaic array PVM and a DC / DC converter DD PV , Photovoltaic array PVM and DC / DC converter DD PV The DC input terminal of the DC / DC converter DD PV The DC output end is connected in parallel to the DC bus DCB; the energy storage unit ESU includes an energy storage device ESD and a bidirectional DC / DC converter DD ES , Energy Storage Device ESD and Bidirectional DC / DC Converter DD ES The DC input terminal is connected to the bidirectional DC / DC converter DD ES The DC output end is connected in parallel to the DC bus DCB, and the energy storage unit ESU can achieve balanced adjustment of electric energy and suppress the random fluctuations of pressure difference electric energy, photovoltaic electric energy and temperature difference electric energy.

3. The electric energy-cold energy comprehensive utilization system combining natural gas pressure energy and solar energy storage according to claim 2 is characterized by: The temperature difference power generation device TED is connected to the pressure difference power generation device PED through a natural gas pipeline, and has cold energy exchange with the pressure difference power generation device PED. The power output port is connected to DD TE The natural gas pipeline equipped with a traditional pressure regulating device TPD is called pipeline branch 1, and a parallel pipeline is led out between the high-pressure natural gas pipeline inlet and the low-pressure natural gas pipeline outlet of pipeline branch 1, which is called pipeline branch 2. The pipeline branch 2 is respectively equipped with an inlet data monitoring unit DMU3, a pressure difference power generation device PED, a temperature difference power generation device TED, a multi-channel flow heat exchanger HEU, and an outlet data monitoring unit DMU4; the inlet data monitoring unit DMU3 can adjust the inlet flow and pressure and monitor the physical quantities such as the inlet natural gas temperature and abnormal state; the pressure difference power generation device PED is connected to the inlet data monitoring unit DMU3, and the high-pressure natural gas can generate electricity and cold energy at the same time after passing through the pressure difference power generation device PED. The power output port is connected to AD PE ; After the multi-channel flow heat exchanger HEU is connected to the temperature difference power generation device TED through the natural gas pipeline, it can recover the cold energy that is not fully utilized in the previous stage. The cooled refrigerant is circulated to the cooling circuits of the DC load DCL and the AC load ACL in the station through the circulating cold source CCS, and is used to cool the production equipment; the low-temperature and low-pressure natural gas after the multi-channel flow heat exchanger HEU is connected to the low-pressure natural gas pipeline outlet on the first branch of the pipeline network through the export data monitoring unit DMU4; The outlet data monitoring unit DMU4 can monitor physical quantities such as outlet temperature, flow, pressure, and abnormal status.

4. The electric energy-cold energy comprehensive utilization system combining natural gas pressure energy and solar energy storage according to claim 2 is characterized by: The pressure difference power generation device PED includes an expander EM and a coaxially connected generator G; the temperature difference power generation device includes a heat exchanger THE and a temperature difference power generation semiconductor TEG; in the single-stage expansion pressure difference power generation refrigeration and temperature difference power generation utilization form, the pressure difference power generation device PED, the temperature difference power generation device TED and the multi-channel flow heat exchanger HEU constitute a gas-electricity-cold modular unit; the pipeline inlet is connected to the expander EM air inlet port, the expander EM air outlet port is connected to the heat exchanger THE inlet, and the generator G coaxially connected to the expander EM is connected to the AC / DC converter AD PE To transmit electric energy, high-pressure natural gas is output as low-temperature and low-pressure natural gas after the action of the expander EM; the low-temperature and low-pressure natural gas can form a temperature difference between the hot and cold sides of the thermoelectric semiconductor TEG after passing through the heat exchanger THE to generate electricity. The circuit output port of the thermoelectric semiconductor TEG is connected to the DC / DC converter DD TE The output port of the heat exchanger THE is then connected to the multi-channel flow heat exchanger HEU in the circulating cold source CCS network, and the refrigerant in the circulating cold source CCS network is used to ensure that the cooling energy of the expanded natural gas is fully utilized; the natural gas heated to a reasonable temperature range is then output through pipelines.

5. The electric energy-cold energy comprehensive utilization system combining natural gas pressure energy and solar energy storage according to claim 3 is characterized by: The pressure difference power generation device PED adopts a single-stage expansion pressure difference power generation, refrigeration and temperature difference power generation utilization form or a multi-stage expansion pressure difference power generation, refrigeration and temperature difference power generation utilization form; the multi-stage expansion pressure difference power generation, refrigeration and temperature difference power generation utilization form cascades the gas-electricity-cold modular unit, which can be applicable to the scene with a high pressure difference ratio of the natural gas pipeline network; the high-pressure natural gas is transported to the inlet port of the expander EM1 of the first-stage gas-electricity-cold modular unit, and after the first-stage expansion power generation and cold energy utilization inside the module, it is output by the first-stage multi-channel flow heat exchanger HEU1; the output port of the first-stage multi-channel flow heat exchanger HEU1 is connected to the inlet port of the expander EM2 of the second-stage gas-electricity-cold modular unit, and after the second-stage expansion power generation and cold energy utilization inside the module, it is output by the second-stage multi-channel flow heat exchanger HEU2; according to the actual pressure and temperature of the output natural gas, it is cascaded to the nth-stage gas-electricity-cold modular unit, and then the natural gas that meets the pressure and temperature range is output and converged through the pipeline; The generator power output ports in each level of gas-electricity-cooling modular units can output individually or lead out the AC busbar for convergence and output according to the actual situation; The power output ports of the temperature difference power generation semiconductors in the gas-electricity-cooling modular units at each level output separately or lead out the DC bus for convergence according to actual conditions; the multi-channel flow heat exchangers in the gas-electricity-cooling modular units at each level are connected to the circulating cold source CCS in the station, giving priority to cooling services within the station.

6. The electric energy-cold energy comprehensive utilization system combining natural gas pressure energy and solar energy storage according to claim 3 is characterized by: The single-stage expansion pressure difference power generation, refrigeration and temperature difference power generation or the parallel multiple expansion pressure difference power generation, refrigeration and temperature difference power generation can be applied to the scene with high pressure difference ratio and large flow of natural gas pipeline network; The gas-electricity-cold modular units are connected in parallel in multiple expansion pressure difference power generation, refrigeration and temperature difference power generation forms, and the parallel number is the corresponding number of shunt branches; each shunt branch is flow-regulated by a branch shunt valve DV, and the branch shunt valve DV is connected between the pipe network inlet and the air inlet port of each branch expander; the generator power output port and the temperature difference power generation semiconductor power output port in each shunt branch are output separately according to actual conditions, or are led out to the AC and DC bus convergence for power conversion; the multi-channel flow heat exchanger in each shunt branch is connected to the circulating cold source CCS in the station, giving priority to the cooling service in the station; the shunt branch 1, shunt branch 2, ..., shunt branch n in the multiple structure are backup for each other, and the system can perform fault-tolerant control operation.

7. The electric energy-cold energy comprehensive utilization system combining natural gas pressure energy and solar energy storage according to claim 1 is characterized by: The form of electric energy utilization in the electric energy-cold energy comprehensive utilization system combining natural gas pressure energy with photovoltaic storage is to select a self-generation and self-use mode or a self-generation and self-use surplus grid-connected mode according to the total annual power generation of the system and the total annual power consumption of AC and DC loads in the station; if the total annual power generation is greater than the total annual power consumption, the self-generation and self-use surplus grid-connected mode is preferentially adopted; if the total annual power generation is less than or equal to the total annual power consumption, the self-generation and self-use mode is preferentially adopted.

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