Energy management method and system for electric hydrogen energy storage system

Abstract

The present invention belongs to the field of microgrid technology, and specifically relates to an energy management method for an electric hydrogen energy storage system, including: obtaining photovoltaic power generation and local load power in the system, and calculating the power required to be consumed by the compressor according to the hydrogen energy storage state of the hydrogen energy storage device and its preset pressure threshold range; judging the energy surplus and shortage state of the system according to the photovoltaic power generation, the local load power of the system and the power required to be consumed by the compressor, and maintaining the energy balance of the system by controlling the operation of the electric energy storage device and the hydrogen energy storage device; after the hydrogen energy storage device is working, recalculating the power required to be consumed by the compressor according to the change in its hydrogen energy storage state, and adjusting the working state of the electric energy storage device and the hydrogen energy storage device according to the new power required to be consumed by the compressor, so as to realize a feedback control cycle. The present invention utilizes the above energy management method to maintain the energy balance and hydrogen balance in the system, as well as the stability of the state of charge of the electric energy storage device.

Description

Technical Field

[0001] The present invention belongs to the technical field of microgrids, and in particular relates to an energy management method and system for an electric hydrogen energy storage system. Background Art

[0002] With the increasing development of renewable energy, the status of energy storage system as an important component of the power grid has been improved accordingly. Energy storage system is usually incorporated into the microgrid of renewable energy to improve the stability of renewable energy.

[0003] Currently, among various energy storage technologies, batteries and capacitors are usually used as short-term energy storage devices to store energy, such as lithium-ion batteries, sodium-ion batteries, solid-state batteries, lithium-ion capacitors, supercapacitors and other electrical devices, while hydrogen energy storage can be used for long-term energy storage technology, such as electrolyzers for preparing hydrogen, fuel cells for consuming hydrogen, and hydrogen storage tanks for storing hydrogen, etc. In response to this, different types of hybrid energy storage systems have been developed, including two or more energy storage technologies, to improve the energy density, power density and cycle life of the energy storage system.

[0004] Among them, energy management methods for electric hydrogen energy storage systems are constantly being developed, which can be roughly divided into rule-based control methods, optimization-based control methods, and learning-based control methods. In particular, rule-based control methods are mainly implemented using high-pass filters or low-pass filters (LPF). For example, the load current is decomposed into high-frequency components and low-frequency components by LPF, and then distributed to the electric energy storage device and the hydrogen energy storage device respectively. However, the disadvantage of the LPF with a fixed cutoff frequency is that when the system operating conditions change, its cutoff frequency cannot be adjusted accordingly, so that the energy storage device may be overcharged or over-discharged.

[0005] On the other hand, the production, storage, transportation and utilization of hydrogen also need to be properly coordinated. In practical applications, isolated or grid-connected microgrids can be used to produce hydrogen or even serve as hydrogen refueling stations. Therefore, the coupling problem between microgrids and hydrogen refueling stations needs to be studied urgently.

[0006] In addition, when incorporating the transportation and utilization of hydrogen into the hydrogen supply chain, attention needs to be paid to the hydrogen flow at different stages to improve the efficiency, safety and economy of the entire supply chain. Summary of the invention

[0007] In view of the above-mentioned shortcomings of the prior art, an object of the present invention is to provide an energy management method applicable to an electric hydrogen energy storage system, which can maintain the energy balance and hydrogen balance in the system, as well as the stable charge state of the electric energy storage device, so that the system can operate stably and reliably.

[0008] To achieve the above-mentioned purpose and other related purposes, the present invention provides an energy management method for an electric hydrogen energy storage system, wherein the electric hydrogen energy storage system is mainly composed of an electric energy storage device and a hydrogen energy storage device, and the electric energy storage device includes but is not limited to one or more of a lithium ion battery, a sodium ion battery, a solid-state battery, a lithium ion capacitor, and a supercapacitor. The energy management method comprises: obtaining photovoltaic power generation power and local load power in the system, and calculating the power required to be consumed by the compressor according to the hydrogen energy storage state (State of Hydrogen Charge, SOHC) of the hydrogen energy storage device and its preset pressure threshold range; judging the energy surplus or shortage state of the system according to the photovoltaic power generation power, the local load power of the system and the power required to be consumed by the compressor, and maintaining the energy balance of the system by controlling the operation of the electric energy storage device and the hydrogen energy storage device; after the hydrogen energy storage device is working, recalculating the power required to be consumed by the compressor according to the change in its hydrogen energy storage state, and adjusting the working state of the electric energy storage device and the hydrogen energy storage device according to the new power required to be consumed by the compressor to realize a feedback control cycle.

[0009] According to a specific embodiment of the present invention, the step of judging the energy surplus or shortage state of the system according to the photovoltaic power generation power, the local load power of the system and the power required to be consumed by the compressor, and maintaining the energy balance of the system by controlling the operation of the electric energy storage device and the hydrogen energy storage device includes: when the sum of the local load power of the system and the power required to be consumed by the compressor is less than the photovoltaic power generation power, judging that the system has energy surplus, and allocating the excess energy to the charging storage of the electric energy storage device and the preparation of hydrogen by the hydrogen energy storage device; when the sum of the local load power of the system and the power required to be consumed by the compressor is greater than the photovoltaic power generation power, judging that the system has energy shortage, controlling the electric energy storage device to discharge and output energy, and controlling the hydrogen energy storage device to consume hydrogen to release energy.

[0010] According to a specific embodiment of the present invention, when the system has energy surplus, the energy balance of the system must satisfy the following:

[0011] P pv -P loadlc -P loadcp ≤P scmax +P elmax ,

[0012] When the system is short of energy, the energy balance of the system must meet the following requirements:

[0013] P loadlc +P loadcp -P pv ≤P scmax +P fcmax ,

[0014] Among them, P pv Represents photovoltaic power generation, P loadlc Represents the local load power of the system, P loadcp Indicates the working power consumed by the compressor, P scmax Indicates the maximum power input of the electric energy storage device for charging, or the maximum power output of the electric energy storage device for discharging, P elmax Indicates the maximum power consumed by the hydrogen storage device to prepare hydrogen, P fcmax Indicates the maximum power output of the hydrogen energy storage device when consuming hydrogen.

[0015] According to a specific embodiment of the present invention, the electric energy storage device includes one or more of a supercapacitor, a lithium-ion battery, a lithium-ion capacitor, a sodium-ion battery, and a solid-state battery, and the hydrogen energy storage device includes an electrolyzer, a fuel cell, and a hydrogen storage tank. The power delivered to the electric energy storage device for charging and the power of the electrolyzer are controlled according to the allocation weight, or the power of the electric energy storage device for discharging and the power of the fuel cell are controlled to maintain the stability of the charge state of the electric energy storage device; and the hydrogen energy storage state of the hydrogen energy storage device is the hydrogen energy storage state of the hydrogen storage tank.

[0016] According to a specific embodiment of the present invention, the allocation weight is an allocation factor of the charging / discharging power of the electric energy storage device, and the cutoff frequency of the low-pass filter in the system is adjusted according to the allocation factor of the charging / discharging power of the electric energy storage device to adjust the power delivered to the electric energy storage device for charging, or to control the power discharged by the electric energy storage device.

[0017] According to a specific embodiment of the present invention, the step of obtaining the distribution factor of the charging / discharging power of the electric energy storage device includes: obtaining the minimum and maximum values ​​of the state of charge of the electric energy storage device according to the normal charging / discharging area and the restricted charging / discharging area of ​​the electric energy storage device, and calculating the initial distribution factor of the electric energy storage device according to the minimum and maximum values ​​of the state of charge; determining the virtual force of the electric energy storage device by using a virtual artificial potential field, and optimizing the initial distribution factor to obtain the target distribution factor of the electric energy storage device, that is, the distribution factor of the charging / discharging power of the electric energy storage device.

[0018] According to a specific embodiment of the present invention, when the electric energy storage device is charged, the initial allocation factor is:

[0019]

[0020] When the electrical energy storage device is discharged, the initial allocation factor is:

[0021]

[0022] Among them, K scfst represents the initial allocation factor, K base Indicates the preset reference coefficient, K tuned Indicates the preset tuning coefficient, SOC min Indicates the minimum value of the state of charge of the energy storage device, SOC max Indicates the maximum value of the state of charge of the energy storage device, SOC refd is the preset first threshold value, and SOC min The area between the energy storage device and the SOC max The area between represents the normal discharge area of ​​the energy storage device, SOC refc is a preset second threshold value, and SOC min The area between the normal charging area of ​​the energy storage device and SOC max Indicates the restricted charging area of ​​the electric energy storage device.

[0023] According to a specific embodiment of the present invention, the formula for calculating the target allocation factor is as follows:

[0024] and

[0025]

[0026] x = SOC - SOC mid ,

[0027] Among them, F sc represents the virtual force of the electric energy storage device, a is a preset parameter, SOC mid is a preset third threshold, and SOC min <SOC mid <SOC max .

[0028] An energy management system for an electric hydrogen energy storage system, comprising: a data acquisition module, used to obtain photovoltaic power generation and local load power in the system, and calculate the power required to be consumed by the compressor according to the hydrogen energy storage state of the hydrogen energy storage device and its preset pressure threshold range; a power allocation module, used to judge the energy surplus or shortage state of the system according to the photovoltaic power generation, the local load power of the system and the power required to be consumed by the compressor, and maintain the energy balance of the system by controlling the operation of the electric energy storage device and the hydrogen energy storage device; a feedback control module, used to recalculate the power required to be consumed by the compressor according to the change in the hydrogen energy storage state after the hydrogen energy storage device is operating, and adjust the operating states of the electric energy storage device and the hydrogen energy storage device according to the new power required to be consumed by the compressor, so as to realize a feedback control cycle.

[0029] An electric hydrogen energy storage system, comprising the energy management system described above, as well as a photovoltaic power source, an electric energy storage device, a hydrogen energy storage device, and a compressor; wherein the electric energy storage device comprises one or more of a supercapacitor, a lithium-ion battery, a lithium-ion capacitor, a sodium-ion battery, and a solid-state battery; the hydrogen energy storage device comprises an electrolyzer, a fuel cell, and a hydrogen storage tank; the electric energy storage device is used to charge and store energy or discharge and output energy; the electrolyzer is used to consume energy to prepare hydrogen and store it in the hydrogen storage tank; the hydrogen storage tank is used to store hydrogen and transport the hydrogen to a hydrogen refueling station through the compressor; the fuel cell is used to consume the hydrogen in the hydrogen storage tank to release energy; wherein the energy management system controls the operation of the electric energy storage device, the electrolyzer, the fuel cell, and the compressor to maintain the energy balance and hydrogen balance of the electric hydrogen energy storage system, and the charge state of the electric energy storage device is stable

[0030] The present invention provides an energy management method. In order to ensure the safety and economy of the electric hydrogen energy storage system, the SOHC of the hydrogen storage tank can be kept within a certain range by controlling the hydrogen flow rate transmitted by the compressor to maintain the hydrogen balance of the system. At the same time, according to the different working modes of the electric hydrogen energy storage system and the working conditions of the compressor, the charging and discharging of the supercapacitor, the energy consumed by the electrolyzer to prepare hydrogen, and the energy released by the fuel cell consuming hydrogen are adjusted accordingly to maintain the energy balance of the system. Secondly, the power distribution between the supercapacitor and the electrolyzer / fuel cell is adjusted by the distribution factor of the supercapacitor charging / discharging power to maintain the stability of the supercapacitor's state of charge. Finally, the electric hydrogen energy storage system is maintained in stable and reliable operation through a feedback control loop. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 A schematic flow chart of a specific embodiment of an energy management method for an electric hydrogen energy storage system provided by the present invention;

[0032] Figure 2 A structural schematic diagram of a specific embodiment of electric energy transmission and hydrogen transmission in the electric hydrogen energy storage system provided by the present invention;

[0033] Figure 3 A curve diagram showing the change of the initial distribution factor with the supercapacitor SOC provided by the present invention;

[0034] Figure 4 A curve diagram showing the target allocation factor provided by the present invention changing with the SOC of the supercapacitor;

[0035] Figure 5 The frequency spectrum corresponding to the target allocation factor provided by the present invention;

[0036] Figure 6A schematic structural diagram of a specific embodiment of an energy management system for an electric hydrogen energy storage system provided by the present invention;

[0037] Figure 7 This is a structural schematic diagram of a specific embodiment of an electric hydrogen energy storage system provided by the present invention. DETAILED DESCRIPTION

[0038] The following will describe the embodiments of the present invention with reference to the accompanying drawings and preferred embodiments. Those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention. It should be understood that the preferred embodiments are only for illustrating the present invention, not for limiting the scope of protection of the present invention.

[0039] It should be noted that the illustrations provided in the following embodiments are only schematic illustrations of the basic concept of the present invention, and thus the drawings only show components related to the present invention rather than being drawn according to the number, shape and size of components in actual implementation. In actual implementation, the type, quantity and proportion of each component may be changed arbitrarily, and the component layout may also be more complicated.

[0040] In the following description, numerous details are discussed to provide a more thorough explanation of the embodiments of the present invention. However, it is obvious to those skilled in the art that the embodiments of the present invention can be implemented without these specific details. In other embodiments, well-known structures and devices are shown in the form of block diagrams rather than in detail to avoid making the embodiments of the present invention difficult to understand.

[0041] First of all, it should be explained that in order to enable people in this technical field to better understand the present application scheme, the technical background of this application is explained accordingly.

[0042] Take the example of an electric hydrogen energy storage system composed of a mixture of supercapacitors and hydrogen components in a microgrid with photovoltaic power generation. As the source of hydrogen production, the electric hydrogen energy storage system must have the ability to produce and store hydrogen, and be able to convert hydrogen into electrical energy to maintain the normal operation of the system and avoid the impact of photovoltaic power generation instability on the system. Therefore, the hydrogen components include electrolyzers, hydrogen storage tanks and fuel cells, which are used for hydrogen production, storage and consumption respectively.

[0043] In addition, in order to transport hydrogen to hydrogen refueling stations and form a hydrogen supply chain, additional hydrogen components are needed, including compressors and transportation pipelines, to compress and transport hydrogen.

[0044] Therefore, the electric hydrogen energy storage system must ensure that the hydrogen storage tank's state of hydrogen charge (SOHC) remains within a certain range to maintain stable and reliable operation of the system. If the SOHC of the hydrogen storage tank is too high, it will affect the safety of the system. If the SOHC of the hydrogen storage tank is too low, it will affect the economic efficiency of the hydrogen supply chain. Therefore, it is necessary to pay attention to the changes in the SOHC of the hydrogen storage tank in real time.

[0045] On the other hand, the electric hydrogen energy storage system must also meet the expected needs of hydrogen refueling stations to maintain the normal operation of the hydrogen supply chain.

[0046] In this regard, this embodiment proposes an energy management method applied to the electric hydrogen energy storage system based on the safety and economy of the electric hydrogen energy storage system to maintain continuous and stable operation of the electric hydrogen energy storage system.

[0047] Example 1

[0048] See also Figure 1-5 As shown, an energy management method for an electric hydrogen energy storage system includes:

[0049] Step S100, obtaining photovoltaic power generation power and local load power in the system, and calculating the power required to be consumed by the compressor according to the hydrogen energy storage state of the hydrogen energy storage device and its preset pressure threshold range.

[0050] In this embodiment, the hydrogen energy storage device includes an electrolyzer for preparing hydrogen, a fuel cell for consuming hydrogen to release energy, and a hydrogen storage tank for storing hydrogen. It is understandable that the hydrogen energy storage state of the hydrogen energy storage device refers to the hydrogen energy storage state of the hydrogen storage tank. The electrical energy storage device can be composed of one or more mixed energy storage devices such as supercapacitors, lithium-ion batteries, lithium-ion capacitors, sodium-ion batteries, solid-state batteries, etc. whose power characteristics are better than those of fuel cells, and there are no excessive restrictions on this. Similarly, the hydrogen energy storage device is the same, and devices with the same functions as electrolyzers, fuel cells, and hydrogen storage tanks are all within the scope of protection of this application.

[0051] In order to more clearly demonstrate the technical solution of the present application, in the following specific embodiments, a supercapacitor is used as an example for the electric energy storage device, and an electrolyzer and a fuel cell are used as examples for the hydrogen energy storage device to illustrate how to manage and control the electric hydrogen energy storage system.

[0052] Among them, photovoltaic power generation power can be understood as the electric energy output by the photovoltaic power supply in the microgrid, which is used to supply the electric hydrogen energy storage system so that it can work normally. For example, the power required for electrolyzing water to prepare hydrogen is provided by the photovoltaic power supply. The local load power in the system can be understood as residential or industrial load. The power consumed by the compressor is calculated according to the SOHC of the hydrogen storage tank. When the SOHC of the hydrogen storage tank is large, it means that there is a large amount of hydrogen in the hydrogen storage tank, resulting in a correspondingly large pressure in the hydrogen storage tank. Considering the safety of the hydrogen storage tank and the needs of the hydrogen refueling station, the hydrogen can be compressed by the compressor and transported to the hydrogen refueling station, which can not only relieve the pressure of the hydrogen storage tank, but also obtain the economic benefits generated by the hydrogen supply chain; when the SOHC of the hydrogen storage tank is small, it means that there is a small amount of hydrogen in the hydrogen storage tank. In order to maintain the stable operation of the system, hydrogen cannot be transported to the hydrogen refueling station. Therefore, the power consumption demand of the compressor is different under different circumstances, and the specific power consumption is calculated according to the amount of hydrogen transmitted.

[0053] It should be noted here that due to the instability of photovoltaic power sources, photovoltaic power generation cannot always meet the power consumption requirements of the electric hydrogen energy storage system. For example, on sunny days, photovoltaic power generation is relatively large, which can meet the local load power in the system and the power required by the compressor. The excess electricity can be stored in supercapacitors for emergency use, and hydrogen can be produced to obtain economic benefits. On cloudy days, photovoltaic power generation is relatively small and cannot support the basic operation of the system. At this time, the electricity stored in the supercapacitor and the electricity output by burning the hydrogen in the hydrogen storage tank can be used to fill the energy shortage in the system. Therefore, the SOHC of the hydrogen storage tank should not be too high or too low, and needs to be kept within a certain range to cope with different conditions.

[0054] Furthermore, in order to enable those skilled in the art to better understand the coupling relationship between the hydrogen storage tank SOHC and the power required to be consumed by the compressor, corresponding explanations are given.

[0055] In order to simplify the actual application scenario, we only take a microgrid electric hydrogen energy storage system supplying hydrogen to a hydrogen refueling station as an example. Figure 2 The electric hydrogen energy storage system shown in the figure. Among them, Buck converter represents a step-down converter, Boost converter represents a step-up converter, Buck-Boost converter represents a step-up / step-down converter, and in this embodiment, the above DC / DC converter is only used to maintain the correct flow direction of power flow to meet the working needs of different devices, and no limitation is imposed.

[0056] In order to control the SOHC of the hydrogen storage tank within a certain range, it is necessary to determine the hydrogen flow rate delivered by the electric hydrogen energy storage system to the hydrogen refueling station, which can be expressed as:

[0057] and

[0058]

[0059]

[0060]

[0061] Where J represents the hydrogen flow in the hydrogen storage tank, W cp Indicates the hydrogen flow compressed and transmitted by the compressor, W hy It represents the net hydrogen flow produced by the system, that is, the difference between the hydrogen production flow of the electrolyzer and the hydrogen consumption flow of the fuel cell, W expected represents the expected hydrogen flow rate of the hydrogen refueling station, and They represent the integer variables corresponding to the different SOHC states of the hydrogen storage tank, α 1 and α 2 Respectively represent the preset weight parameters.

[0062] Based on the above formula, it can be understood that when SOHC≤SOHC low When the hydrogen flow in the hydrogen storage tank is cp -W hy In this case, since the SOHC of the hydrogen storage tank is lower than the preset range, in order to maintain the stable and reliable operation of the electric hydrogen system, W cp should be as small as possible, and when W cp =0, that is, no hydrogen is compressed and transported to the hydrogen filling station; when SOHC≥SOHC high When the SOHC of the hydrogen storage tank is higher than the preset range, in order to maintain the safety of the electric hydrogen system and improve the economic benefits, W cp It should be as large as possible to allow hydrogen in the hydrogen storage tank to be transported to the hydrogen filling station to reduce SOHC; when SOHC low <SOHC<SOHC high When the weight parameter α 1 and α 2 Optimize so that W cp It can maximize the needs of the electric hydrogen energy storage system to keep the hydrogen storage state of the hydrogen storage tank within a certain range to maintain stable and reliable operation of the system, and the electric hydrogen energy storage system needs to meet the expected needs of the hydrogen refueling station to maintain the normal operation of the hydrogen supply chain.

[0063] Step S200, judging the energy surplus or shortage state of the system according to the photovoltaic power generation power, the local load power of the system and the power required to be consumed by the compressor, and maintaining the energy balance of the system by controlling the operation of the electric energy storage device and the hydrogen energy storage device.

[0064] Specifically, the electric-hydrogen energy storage system mainly operates in two modes. When the photovoltaic power generation is sufficient, the system has energy surplus. At this time, both the electric energy storage device and the hydrogen energy storage device can be used as loads to consume excess power. That is, when the sum of the system's local load power and the power required by the compressor is less than the photovoltaic power generation, the excess energy can be allocated to supercapacitor charging storage and electrolyzer hydrogen preparation. When the photovoltaic power generation is less, the system is short of energy. At this time, the electric energy storage device and the hydrogen energy storage device are used as energy sources to make up for the shortage of photovoltaic power generation. That is, when the sum of the system's local load power and the power required by the compressor is greater than the photovoltaic power generation, the energy is released by controlling the discharge of the supercapacitor and the operation of the fuel cell.

[0065] Furthermore, in order to maintain the energy balance of the electric hydrogen energy storage system in the two modes, the following requirements need to be met respectively:

[0066] System energy surplus: P pv -P loadlc -P loadcp ≤P scmax +P elmax ,

[0067] System energy shortage: P loadlc +P loadcp -P pv ≤P scmax +P fcmax ,

[0068] Among them, P pv Represents photovoltaic power generation, P loadlc Represents the local load power of the system, P loadcp Indicates the working power consumed by the compressor, P scmax Indicates the maximum power input of the electric energy storage device for charging, or the maximum power output of the electric energy storage device for discharging, P elmax It represents the maximum power consumed by the hydrogen storage device to prepare hydrogen, that is, the maximum power of the electrolyzer, P fcmax It indicates the maximum power output of the hydrogen energy storage device when consuming hydrogen, that is, the maximum power at which the fuel cell operates.

[0069] It should be noted that the electric energy storage device is a supercapacitor, and the maximum power of the supercapacitor during charging and discharging is the same, so only P is used. scmax A value is used instead.

[0070] According to the above formula, it can be understood that the net load power of the electric hydrogen energy storage system under the microgrid cannot exceed the sum of the maximum power of the supercapacitor and the maximum power of the electrolyzer / fuel cell, so that when the system has energy surplus, the excess photovoltaic power generation power can be charged and stored by the supercapacitor and consumed by the electrolyzer to prepare hydrogen; and when the system is short of energy, the maximum discharge power of the supercapacitor and the maximum operating power of the fuel cell can fill the energy shortage caused by the photovoltaic power generation power to maintain the normal operation of the system.

[0071] Furthermore, in order to optimize the power distribution of the system under different operating modes, the present embodiment also provides corresponding distribution weight parameters to control the input power for charging the supercapacitor and the input power for the electrolyzer, or to control the output power for discharging the supercapacitor and the output power for the fuel cell, so as to maintain the stability of the supercapacitor charge state.

[0072] Specifically, when the system has energy surplus, the supercapacitor is charged and stored, and when the system has energy shortage, the supercapacitor is discharged and output. Therefore, by controlling the charging / discharging power of the supercapacitor, the power distribution of the system in different working modes can be optimized. In this embodiment, the distribution weight is the distribution factor for controlling the charging / discharging power of the supercapacitor, and the cutoff frequency of the low-pass filter is adjusted by the distribution factor, so that the power distribution is adjusted accordingly.

[0073] In a specific embodiment, the step of obtaining the allocation factor of the supercapacitor charging / discharging power includes:

[0074] First, the minimum and maximum values ​​of the state of charge (SOC) of the supercapacitor are obtained according to the normal charge / discharge region and the restricted charge / discharge region of the supercapacitor, and the initial allocation factor of the supercapacitor is calculated according to the minimum and maximum values ​​of the SOC.

[0075] It is understandable that supercapacitors have a high SOC min and SOC max Operate within the limited SOC range, SOC min It is the lower limit of operation, below which the supercapacitor is not allowed to discharge further, SOC max It is the upper limit of operation, above which the supercapacitor is not allowed to be charged further to ensure the safe operation of the supercapacitor and extend its service life.

[0076] Furthermore, the threshold SOC is introduced refd The range of supercapacitor SOC can be divided into normal discharge area and limited discharge area, that is, SOC refd and SOC max The area between is the normal discharge area, SOC min and SOCrefd The area between is the discharge limit area. Similarly, the threshold SOC is introduced refc The range of supercapacitor SOC can be divided into normal charging area and restricted charging area, namely SOC min and SOC refc The area between is the normal charging area, SOC refc and SOC max The areas between are restricted charging areas.

[0077] Therefore, when the supercapacitor is charged, the initial distribution factor is:

[0078]

[0079] When the supercapacitor is discharged, the initial distribution factor is:

[0080]

[0081] Among them, K scfst represents the initial allocation factor, K base Indicates the preset reference coefficient, K tuned Indicates the preset tuning coefficient, SOC min Indicates the minimum value of the supercapacitor SOC, SOC max Indicates the maximum value of the supercapacitor SOC, SOC refd Indicates the preset first threshold, SOC refc Indicates the preset second threshold.

[0082] Secondly, the virtual force of the supercapacitor is determined by using a virtual artificial potential field, and the initial distribution factor is optimized to obtain the target distribution factor of the supercapacitor, that is, the distribution factor of the supercapacitor charging / discharging power.

[0083] Among them, the virtual force F of the supercapacitor is determined by using a virtual artificial potential field. sc :

[0084]

[0085] Where x = SOC-SOC mid =0, and SOC mid It is a SOC min and SOC max The value between is the SOC of the supercapacitor that is expected to operate, which can be adjusted accordingly according to the actual situation. In this embodiment, it corresponds to the preset third threshold. The preset parameter a determines the virtual force F sc Therefore, the virtual force F of the supercapacitor can be sc For the initial allocation factor K scfst Further optimization, the target allocation factor K is obtainedscsnd :

[0086]

[0087] It should be noted that the SOC of the supercapacitor should be maintained within an appropriate range and can have a certain power buffer. Artificial potential fields are widely used in formation control of multiple agents. In the formation problem, multiple agents must maintain a reference distance to form a stable formation. This method can construct an artificial potential field, and the force function between any two agents in the artificial potential field is also called the action function. When the distance between the two agents is equal to the reference value, no force is generated between them, that is, the potential energy is zero. When the two are close, there will be a greater repulsive force; when they are far away from each other, there is a greater attraction. This high potential energy (i.e. repulsion or attraction) can ensure that their distance quickly converges to the reference value.

[0088] Therefore, the relationship between the power allocation strategy and the virtual force is as follows: the SOC of the supercapacitor can be defined as the virtual distance. In the discharge mode, when the SOC is high, there is an attraction to reduce the SOC, that is, the supercapacitor bears more load power; when the SOC is low, there is an attraction to increase the SOC, that is, the supercapacitor bears less load power. Similarly, in the charging mode, the same is true, and when the SOC is close to or equal to the reference value, the above phenomenon can be effectively reduced, that is, the load power borne by the supercapacitor is of appropriate size.

[0089] Based on the above, in this embodiment, the initial allocation factor is optimized by the virtual force corresponding to the supercapacitor SOC.

[0090] In a specific embodiment, reference may be made to Figure 3 , 4 , 5, taking discharge as an example, K scfst The piecewise linear function of SOC, and K scsnd It is a nonlinear function of SOC. When SOC = SOC mid When x = SOC-SOC mid =0, virtual force F sc The corresponding value is 0, and K scsnd =K scfst When SOC deviates from SOC mid When x starts to increase, the virtual force F sc Especially when SOC = SOC max When SOC=SOC min When K scsnd With K scfst There are significant differences.

[0091] Physically, these results can be understood as follows: when SOC is close to SOC mid , that is, when referring to the expected value, K scsnd The SOC within a certain range is approximately the same, that is, K scsnd The curve approaches flatness. Therefore, a relatively fixed power is allocated to the supercapacitor. When the SOC approaches the lower limit SOC min and upper limit SOC max Time K scsnd significantly lower or higher, which means less or more power is allocated to the supercapacitor, and K scsnd and K scfst The difference is the gain after virtual force optimization.

[0092] Among them, the reasons for the optimization part can be understood as follows: when the SOC of the supercapacitor is relatively low, it should be discharged slowly at a lower power, which helps to avoid potential over-discharge and ensure the safety of the supercapacitor; when the SOC is relatively high, the supercapacitor can be released faster with a higher power, which can reduce the power to be loaded by the hydrogen energy storage device to improve the economy of the system.

[0093] Further, Figure 5 The spectrum shown in the figure shows that due to K scsnd It is the ratio of the area of ​​the high frequency part of the spectrum to the total area of ​​the spectrum. Therefore, K scsnd The smaller the K, the lower the cutoff frequency. scsnd A larger value corresponds to a higher cutoff frequency.

[0094] In summary, after calculating the supercapacitor charging / discharging power allocation factor, the low-pass filter cutoff frequency can be adjusted accordingly to achieve power allocation. Specifically, in practical applications, the DC bus reference current generated by the DC bus voltage through the voltage loop is decomposed into a low-frequency component and a high-frequency component by the low-pass filter. The low-frequency component can be used as a reference current for the operation of a fuel cell or an electrolyzer, and the high-frequency component can be used as a reference current for supercapacitor charging or discharging. The cutoff frequency of the low-pass filter is generated accordingly by the supercapacitor charging / discharging power allocation factor.

[0095] It can be seen that the weight parameters provided in this embodiment can realize the power distribution of the system in different working modes, thereby maintaining the stability of the supercapacitor's state of charge.

[0096] Step S300, after the hydrogen energy storage device is working, the power required to be consumed by the compressor is recalculated according to the change in its hydrogen energy storage state, and the working states of the electric energy storage device and the hydrogen energy storage device are adjusted according to the new power required to be consumed by the compressor to realize a feedback control cycle.

[0097] It is understandable that after step S200, the working condition of the hydrogen energy storage device needs to be adjusted accordingly according to different working modes of the system, that is, hydrogen is prepared by working of the electrolyzer or hydrogen is consumed by working of the fuel cell, thereby causing the SOHC of the hydrogen storage tank to change. In order to keep its SOHC within a preset range, the working condition of the compressor is adjusted, that is, the amount of hydrogen compressed by the compressor is adjusted to maintain the SOHC balance of the hydrogen storage tank. For details, see Figure 2 Therefore, after the electrolyzer or the fuel cell is working, the hydrogen flow rate W to be compressed by the compressor is recalculated according to the change in the hydrogen storage tank SOHC, that is, the increase or decrease cp , and then according to the hydrogen flow rate W cp The power consumed by the system is calculated to re-identify the system's operating mode, and the power distribution is adjusted accordingly, thereby continuing to maintain the system's energy balance and hydrogen balance, realizing a feedback control cycle and improving the stability of the electric hydrogen energy storage system.

[0098] It should be added here that the hydrogen production model of the electrolyzer is based on the hydrogen production rate W el and Faraday efficiency η F Representation can be written as:

[0099]

[0100] Among them, i el Represents the working current of the electrolytic cell, n C Indicates the number of electrolyzer cells connected in series, F, f 1 , f 2 They represent the Faraday constant and S represents the surface area of ​​the electrolytic cell.

[0101] The hydrogen consumption rate of the fuel cell is W fc It can be written as:

[0102]

[0103] Among them, i fc represents the fuel cell operating current, p hy represents the hydrogen pressure at the fuel cell inlet, R and F are constants, T represents the temperature, N c represents the number of monomers contained in the fuel cell, z is the number of mobile electrons, η cov represents the hydrogen conversion rate, η hy Indicates the proportion of hydrogen in the fuel cell.

[0104] The amount of hydrogen stored in the hydrogen storage tank n hst It can be written as:

[0105]

[0106] Among them, n init Indicates the initial amount of hydrogen in the hydrogen storage tank.

[0107] Based on the above formulas, the range of the hydrogen storage tank SOHC to be maintained and the hydrogen production rate W of the electrolyzer can be calculated. el and the fuel cell's hydrogen consumption rate W fc Calculate the hydrogen flow rate W that the compressor needs to compress cp , thereby realizing the above-mentioned feedback control.

[0108] In summary, the energy management method provided in this embodiment can adjust the power distribution in the system according to the range to be maintained by the hydrogen storage tank SOHC and the supercapacitor SOC to control the working conditions of the supercapacitor, electrolyzer, fuel cell, and compressor to maintain the energy balance and hydrogen balance of the system, as well as the stability of the charge state of the supercapacitor.

[0109] It should be noted that the step division of the above methods is only for clear description. When implemented, they can be combined into one step or some steps can be split and decomposed into multiple steps. As long as they contain the same logical relationship, they are all within the scope of protection of this patent; adding insignificant modifications to the algorithm or process or introducing insignificant designs without changing the core design of the algorithm and process are all within the scope of protection of this patent.

[0110] Example 2

[0111] See also Figure 6 As shown, the embodiment of the present application also provides an energy management system for an electric hydrogen energy storage system, including:

[0112] The data acquisition module 10 is used to obtain the photovoltaic power generation and the local load power in the system, and calculate the power required to be consumed by the compressor according to the hydrogen energy storage state of the hydrogen energy storage device and its preset pressure threshold range;

[0113] A power distribution module 20 is used to determine the energy surplus or shortage state of the system according to the photovoltaic power generation power, the local load power of the system and the power required to be consumed by the compressor, and to maintain the energy balance of the system by controlling the operation of the electric energy storage device and the hydrogen energy storage device;

[0114] The feedback control module 30 is used to recalculate the power required to be consumed by the compressor according to the change in the hydrogen energy storage state after the hydrogen energy storage device is working, and adjust the working states of the electric energy storage device and the hydrogen energy storage device according to the new power required to be consumed by the compressor to realize a feedback control cycle.

[0115] It should be noted that the energy management system of the electric hydrogen energy storage system provided in the above embodiment and the energy management method of the electric hydrogen energy storage system provided in the above embodiment 1 belong to the same concept, wherein the specific manner in which each module and unit performs the operation has been described in detail in the method embodiment, and will not be repeated here. In practical applications, the energy management method of the electric hydrogen energy storage system provided in the above embodiment 1 can allocate the above functions to different functional modules as needed, that is, divide the internal structure of the device into different functional modules to complete all or part of the functions described above, and this is not limited here.

[0116] Example 3

[0117] See also Figure 7 As shown, the embodiment of the present application also provides an electric hydrogen energy storage system, including the energy management system 100 in the above embodiment 2, as well as a photovoltaic power source 200, an electric energy storage device, a hydrogen energy storage device, and a compressor 300. Among them, the electric energy storage device includes one or more of a supercapacitor, a lithium-ion battery, a lithium-ion capacitor, a sodium-ion battery, and a solid-state battery, and specifically takes the supercapacitor 400 as an example; the hydrogen energy storage device includes an electrolyzer 500, a fuel cell 600, and a hydrogen storage tank 700.

[0118] Specifically, in actual applications, the photovoltaic power source 200 is used to output the photovoltaic power generation mentioned in the above embodiments, the supercapacitor 400 is used to charge and store energy when the system has energy surplus or to discharge and output energy when the system has energy shortage, the electrolyzer 500 consumes energy to prepare hydrogen when the system has energy surplus, stores it in the hydrogen storage tank 700, and transports the hydrogen to the hydrogen refueling station through the compressor 300, and the fuel cell 600 consumes the hydrogen in the hydrogen storage tank 700 to release energy when the system has energy shortage.

[0119] Accordingly, the energy management system 100 controls the operation of the supercapacitor 400, the electrolyzer 500, the fuel cell 600 and the compressor 300 and adjusts them according to actual conditions to maintain the energy balance and hydrogen balance of the electric hydrogen energy storage system and the stable charge state of the supercapacitor.

[0120] In summary, the present invention provides an energy management method. In order to ensure the safety and economy of the electric hydrogen energy storage system, the SOHC of the hydrogen storage tank can be kept within a certain range by controlling the hydrogen flow rate transmitted by the compressor to maintain the hydrogen balance of the system. At the same time, according to the different working modes of the electric hydrogen energy storage system and the working conditions of the compressor, the charging and discharging of the supercapacitor, the energy consumed by the electrolyzer to prepare hydrogen, and the energy released by the fuel cell consuming hydrogen are adjusted accordingly to maintain the energy balance of the system. Secondly, the power distribution between the supercapacitor and the electrolyzer / fuel cell is adjusted by the distribution factor of the supercapacitor charging / discharging power to maintain the stability of the supercapacitor's state of charge. Finally, the electric hydrogen energy storage system is maintained in stable and reliable operation through a feedback control loop.

[0121] The above embodiments are merely illustrative of the principles and effects of the present invention, and are not intended to limit the present invention. Anyone familiar with the technology may modify or change the above embodiments without violating the spirit and scope of the present invention. Therefore, all equivalent modifications or changes made by a person of ordinary skill in the art without departing from the spirit and technical ideas disclosed by the present invention shall still be covered by the claims of the present invention.

Claims

1. An energy management method for an electric hydrogen energy storage system, characterized in that: include: Obtain the photovoltaic power generation and the local load power in the system, and calculate the power required by the compressor based on the hydrogen energy storage state of the hydrogen energy storage device and its preset pressure threshold range; Determine the energy surplus or shortage state of the system according to the photovoltaic power generation, the local load power of the system and the power required to be consumed by the compressor, and maintain the energy balance of the system by controlling the operation of the electric energy storage device and the hydrogen energy storage device; After the hydrogen energy storage device is working, the power required to be consumed by the compressor is recalculated according to the change in the hydrogen energy storage state, and the working states of the electric energy storage device and the hydrogen energy storage device are adjusted according to the new power required to be consumed by the compressor to realize a feedback control cycle; Wherein, when controlling the charging / discharging of the electric energy storage device, the power delivered to the electric energy storage device for charging is controlled or the power of the electric energy storage device for discharging is controlled according to the allocation weight; and the allocation weight is the allocation factor of the charging / discharging power of the electric energy storage device, and the cutoff frequency of the low-pass filter in the system is adjusted by the allocation factor of the charging / discharging power of the electric energy storage device to adjust the power delivered to the electric energy storage device for charging, or control the power of the electric energy storage device for discharging; The step of obtaining the distribution factor of the charging / discharging power of the electric energy storage device includes: obtaining the minimum and maximum values ​​of the state of charge of the electric energy storage device according to the normal charging / discharging area and the restricted charging / discharging area of ​​the electric energy storage device, and calculating the initial distribution factor of the electric energy storage device according to the minimum and maximum values ​​of the state of charge; determining the virtual force of the electric energy storage device by using a virtual artificial potential field, and optimizing the initial distribution factor to obtain the target distribution factor of the electric energy storage device, that is, the distribution factor of the charging / discharging power of the electric energy storage device; and the formula for calculating the target distribution factor is as follows: and x=SOC-SOC mid , K scfst represents the initial allocation factor, K scsnd represents the target allocation factor, F sc represents the virtual force of the electric energy storage device, a is a preset parameter, SOC mid is a preset third threshold, and SOC min <SOC mid <SOC max .

2. The energy management method of the electric hydrogen energy storage system according to claim 1, characterized in that: The steps of determining the energy surplus or shortage state of the system according to the photovoltaic power generation power, the local load power of the system and the power required to be consumed by the compressor, and maintaining the energy balance of the system by controlling the operation of the electric energy storage device and the hydrogen energy storage device include: When the sum of the local load power of the system and the power required to be consumed by the compressor is less than the photovoltaic power generation power, it is determined that the system has energy surplus, and the excess energy is allocated to charging and storing the electric energy storage device and preparing hydrogen by the hydrogen energy storage device; When the sum of the local load power of the system and the power required to be consumed by the compressor is greater than the photovoltaic power generation power, the system is judged to be short of energy, and the electric energy storage device is controlled to discharge and output energy, and the hydrogen energy storage device is controlled to consume hydrogen to release energy.

3. The energy management method of the electric hydrogen energy storage system according to claim 2, characterized in that: When the system has energy surplus, the energy balance of the system must satisfy the following: P pv -P loadlc -P loadcp ≤P scmax +P elmax , When the system is short of energy, the energy balance of the system must meet the following requirements: P loadlc +P loadcp -P pv ≤P scmax +P fcmax , Among them, P pv Represents photovoltaic power generation, P loadlc Represents the local load power of the system, P loadcp Indicates the working power consumed by the compressor, P scmax Indicates the maximum power input of the electric energy storage device for charging, or the maximum power output of the electric energy storage device for discharging, P elmax Indicates the maximum power consumed by the hydrogen storage device to prepare hydrogen, P fcmax Indicates the maximum power output of the hydrogen energy storage device when consuming hydrogen.

4. The energy management method of the electric hydrogen energy storage system according to claim 2, characterized in that: The electrical energy storage device includes one or more of a supercapacitor, a lithium-ion battery, a lithium-ion capacitor, a sodium-ion battery, and a solid-state battery, and the hydrogen energy storage device includes an electrolyzer, a fuel cell, and a hydrogen storage tank. The power delivered to the electric energy storage device for charging and the power of the electrolyzer for operation are controlled according to the allocation weight, or the power of the electric energy storage device for discharging and the power of the fuel cell for operation are controlled to maintain the stability of the charge state of the electric energy storage device; and the hydrogen energy storage state of the hydrogen energy storage device is the hydrogen energy storage state of the hydrogen storage tank.

5. The energy management method of the electric hydrogen energy storage system according to claim 1, characterized in that: The formula for calculating the initial allocation factor is as follows: When the electrical energy storage device is charged, the initial allocation factor is: When the electrical energy storage device is discharged, the initial allocation factor is: Among them, K scfst represents the initial allocation factor, K base Indicates the preset reference coefficient, K tuned Indicates the preset tuning coefficient, SOC min Indicates the minimum value of the state of charge of the energy storage device, SOC max Indicates the maximum value of the state of charge of the energy storage device, SOC refd is the preset first threshold value, and SOC min The area between the energy storage device and the SOC max The area between represents the normal discharge area of ​​the energy storage device, SOC refc is a preset second threshold value, and SOC min The normal charging area of ​​the energy storage device is represented by the SOC max Indicates the restricted charging area of ​​the electric energy storage device.

6. An energy management system for an electric hydrogen energy storage system, characterized in that: include: The data acquisition module is used to obtain the photovoltaic power generation and the local load power in the system, and calculate the power required by the compressor according to the hydrogen energy storage state of the hydrogen energy storage device and its preset pressure threshold range; A power distribution module, used to determine the energy surplus or shortage state of the system according to the photovoltaic power generation power, the local load power of the system and the power required to be consumed by the compressor, and to maintain the energy balance of the system by controlling the operation of the electric energy storage device and the hydrogen energy storage device; A feedback control module, used for recalculating the power required to be consumed by the compressor according to the change in the hydrogen energy storage state after the hydrogen energy storage device is in operation, and adjusting the working states of the electric energy storage device and the hydrogen energy storage device according to the new power required to be consumed by the compressor, so as to realize a feedback control cycle; Wherein, when controlling the charging / discharging of the electric energy storage device, the power delivered to the electric energy storage device for charging is controlled or the power of the electric energy storage device for discharging is controlled according to the allocation weight; and the allocation weight is the allocation factor of the charging / discharging power of the electric energy storage device, and the cutoff frequency of the low-pass filter in the system is adjusted by the allocation factor of the charging / discharging power of the electric energy storage device to adjust the power delivered to the electric energy storage device for charging, or control the power of the electric energy storage device for discharging; The step of obtaining the distribution factor of the charging / discharging power of the electric energy storage device includes: obtaining the minimum and maximum values ​​of the state of charge of the electric energy storage device according to the normal charging / discharging area and the restricted charging / discharging area of ​​the electric energy storage device, and calculating the initial distribution factor of the electric energy storage device according to the minimum and maximum values ​​of the state of charge; determining the virtual force of the electric energy storage device by using a virtual artificial potential field, and optimizing the initial distribution factor to obtain the target distribution factor of the electric energy storage device, that is, the distribution factor of the charging / discharging power of the electric energy storage device; and the formula for calculating the target distribution factor is as follows: and x=SOC-SOC mid , K scfst represents the initial allocation factor, K scsnd represents the target allocation factor, F sc represents the virtual force of the electric energy storage device, a is a preset parameter, SOC mid is a preset third threshold, and SOC min <SOC mid <SOC max .

7. An electric hydrogen energy storage system, characterized in that: The energy management system comprises the energy management system as claimed in claim 6 above, as well as a photovoltaic power source, an electric energy storage device, a hydrogen energy storage device, and a compressor; wherein the electric energy storage device comprises one or more of a supercapacitor, a lithium-ion battery, a lithium-ion capacitor, a sodium-ion battery, and a solid-state battery; and the hydrogen energy storage device comprises an electrolyzer, a fuel cell, and a hydrogen storage tank; The electrical energy storage device is used for charging and storing energy or discharging and outputting energy; The electrolyzer is used to consume energy to produce hydrogen, and store it in the hydrogen storage tank; The hydrogen storage tank is used to store hydrogen, and the hydrogen is transported to the hydrogen filling station through the compressor; The fuel cell is used to consume the hydrogen in the hydrogen storage tank to release energy; The energy management system controls the operation of the electric energy storage device, the electrolyzer, the fuel cell and the compressor to maintain the energy balance and hydrogen balance of the electric hydrogen energy storage system and the stable state of charge of the electric energy storage device.

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