A photovoltaic micro-grid control method, device and system

Abstract

The present application belongs to the technical field of micro-grid, and particularly relates to a photovoltaic micro-grid control method, device and system, wherein the photovoltaic micro-grid comprises a photovoltaic power generation device, an electric energy storage device and a hydrogen energy storage device; the method comprises the following steps: determining the working mode of the photovoltaic micro-grid according to the energy demand state of the photovoltaic micro-grid, the state of charge of the electric energy storage device and the equivalent state of charge of the hydrogen energy storage device; when the working mode is the electric-hydrogen hybrid energy storage state or the electric-hydrogen hybrid energy supply state, controlling the energy storage or energy supply of the electric energy storage device and the hydrogen energy storage device through a preset control strategy; when the working mode is the electric-hydrogen hybrid energy supply state or the hydrogen energy supply state, controlling the hydrogen flow of the fuel cell of the input hydrogen energy storage device according to an internal hydrogen flow adjustment strategy. The present application dynamically adjusts the state of charge of the electric energy storage device and the equivalent state of charge of the hydrogen energy storage device through the preset control strategy, the internal hydrogen flow adjustment strategy and the external hydrogen flow adjustment strategy, thereby preventing overcharging or over-discharging of the energy storage components.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of micro-grid, and particularly relates to a photovoltaic micro-grid control method, device and system. BACKGROUND

[0002] With the increasingly serious energy crisis and environmental problems, the construction of a micro-grid with renewable energy has become an important solution to the problem. Due to the intermittency and uncertainty of renewable energy, energy storage is becoming a key component of micro-grid. Among various energy storage technologies, electric energy storage is usually used as a short-term energy storage technology due to its high power density. On the other hand, hydrogen energy storage, including electrolytic tank, hydrogen storage tank and fuel cell, has more advantages in energy density and is a promising long-term energy storage technology. Therefore, the two can be combined for energy storage.

[0003] In order to reasonably allocate power to different energy storage components, a low-pass filter (LPF) is usually used to divide the power into high-frequency and low-frequency parts, and allocate them to components with fast response (such as super capacitor) and slow response (such as fuel cell and electrolytic tank) respectively. Generally, the cutoff frequency of the LPF is fixed, which may cause overcharging or overdischarging of certain energy storage components (such as super capacitor). On the other hand, if the production, storage and transportation of hydrogen are not well coordinated, the equivalent state of hydrogen charge (SOHC) of the hydrogen storage tank may be too high, which may damage the hydrogen storage tank. SUMMARY

[0004] In view of the above-mentioned shortcomings of the prior art, the present application provides a photovoltaic micro-grid control method, device and system capable of dynamically allocating energy storage and power supply of electric energy storage device and hydrogen energy storage device, and coordinating hydrogen flow of the hydrogen energy storage device.

[0005] To achieve the above-mentioned purpose and other related purposes, the present application provides a photovoltaic micro-grid control method, which comprises a photovoltaic power generation device, an electric energy storage device and a hydrogen energy storage device, and the method comprises:

[0006] obtaining the energy demand state of the photovoltaic micro-grid, the state of charge of the electric energy storage device and the equivalent state of charge of the hydrogen energy storage device, and determining the working mode of the photovoltaic micro-grid;

[0007] when the working mode is an electric-hydrogen hybrid energy storage state or an electric-hydrogen hybrid energy supply state, controlling the electric energy storage device and the hydrogen energy storage device to store energy or supply energy through a preset control strategy;

[0008] controlling the hydrogen flow rate of the fuel cell of the hydrogen energy storage device according to an internal hydrogen flow regulation strategy when the working mode is the electric-hydrogen hybrid energy storage state or the hydrogen energy state.

[0009] In an embodiment of the present application, the step of obtaining the energy demand state of the photovoltaic micro-grid, the state of charge of the electric energy storage device and the equivalent state of charge of the hydrogen energy storage device, and determining the working mode of the photovoltaic micro-grid comprises:

[0010] if the energy demand state is surplus and the state of charge is less than a preset maximum state of charge and the equivalent state of charge is less than a preset maximum equivalent state of charge, the working mode is the electric-hydrogen hybrid energy storage state;

[0011] if the energy demand state is deficit and the equivalent state of charge is greater than a preset minimum equivalent state of charge and the state of charge is less than or equal to a preset minimum state of charge, the working mode is the hydrogen energy state;

[0012] if the energy demand state is deficit and the state of charge is greater than the minimum state of charge and the equivalent state of charge is greater than the minimum equivalent state of charge, the working mode is the electric-hydrogen hybrid energy state.

[0013] In an embodiment of the present application, the step of controlling the energy storage or energy supply of the electric energy storage device and the hydrogen energy storage device through a preset control strategy when the working mode is the electric-hydrogen hybrid energy storage state or the electric-hydrogen hybrid energy state comprises:

[0014] adjusting the cutoff frequency of a low-pass filter through an adaptive power distribution strategy when the working mode is the electric-hydrogen hybrid energy storage state or the electric-hydrogen hybrid energy state;

[0015] allocating the high-frequency part of the energy to the electric energy storage device and the low-frequency part of the energy to the hydrogen energy storage device through the low-pass filter when the working mode is the electric-hydrogen hybrid energy storage state;

[0016] making the electric energy storage device provide high-frequency energy and the hydrogen energy storage device provide low-frequency energy through the low-pass filter when the working mode is the electric-hydrogen hybrid energy state.

[0017] In an embodiment of the present application, the adaptive power distribution strategy comprises:

[0018] calculating a virtual artificial potential field according to the state of charge;

[0019] calculating a spectral area ratio and determining the cutoff frequency according to the difference between the current of the load connected to the photovoltaic micro-grid and the photovoltaic power generation device and the virtual artificial potential field.

[0020] In one embodiment of the present application, when the working mode is the electric-hydrogen hybrid power supply state or the hydrogen power supply state, the hydrogen flow rate input to the hydrogen storage energy device is controlled according to the internal hydrogen flow adjustment strategy by the following formula:

[0021]

[0022] where W fc is the hydrogen flow rate input to the fuel cell, i fc is the actual working current of the fuel cell, R and F are constants, T is temperature, N c is the number of single cells contained in the fuel cell stack, z is the number of transferred electrons, P in is the hydrogen pressure at the inlet of the fuel cell, η cov is the hydrogen conversion rate, η H is the hydrogen proportion in the fuel, i netload is the current difference between the load and the photovoltaic power generation device.

[0023] In one embodiment of the present application, the method further comprises:

[0024] When the energy demand state is surplus and the equivalent state of charge is greater than the minimum equivalent state of charge, or when the energy demand state is deficit and the equivalent state of charge is greater than the preset first reference value of the equivalent state of charge, the hydrogen flow rate of hydrogen output by the hydrogen storage energy device is controlled according to the external hydrogen flow adjustment strategy.

[0025] In one embodiment of the present application, the hydrogen flow rate of hydrogen output by the hydrogen storage energy device is controlled according to the external hydrogen flow adjustment strategy by the following formula:

[0026]

[0027] where W cp is the hydrogen flow rate of hydrogen output by the hydrogen storage energy device, SOHC is the equivalent state of charge, W0 is the rated hydrogen flow rate of the compressor flowing into the hydrogen storage energy device, α c and α s are tuning factors, ω c and ω s are constants, netload is the current difference between the load and the photovoltaic power generation device, SOHC ref is the first reference value of the equivalent state of charge.

[0028] In one embodiment of the present application, the method further comprises:

[0029] When the state of charge is greater than or equal to a preset state of charge reference value or the equivalent state of charge is greater than or equal to a preset equivalent state of charge second reference value, the photovoltaic power generation device is controlled to reduce output power.

[0030] To achieve the above object and other related objects, the present application further provides a photovoltaic micro-grid control device, comprising:

[0031] a working mode determination module, configured to acquire an energy demand state of the photovoltaic micro-grid, a state of charge of the electric energy storage device and an equivalent state of charge of the hydrogen energy storage device, and determine a working mode of the photovoltaic micro-grid;

[0032] an electric-hydrogen hybrid control module, configured to control the electric energy storage device and the hydrogen energy storage device to store energy or supply energy through a preset control strategy when the working mode is an electric-hydrogen hybrid energy storage state or an electric-hydrogen hybrid energy supply state;

[0033] a hydrogen flow coordination module, configured to control a hydrogen flow rate of a fuel cell inputting into the hydrogen energy storage device according to an internal hydrogen flow adjustment strategy when the working mode is the electric-hydrogen hybrid energy supply state or a hydrogen energy supply state.

[0034] To achieve the above object and other related objects, the present application further provides a photovoltaic micro-grid control system, comprising:

[0035] a photovoltaic micro-grid and the photovoltaic micro-grid control device;

[0036] the photovoltaic micro-grid control device is configured to connect and control the photovoltaic micro-grid;

[0037] the photovoltaic micro-grid comprises:

[0038] a photovoltaic power generation device, configured to output energy to a load connected to the photovoltaic micro-grid and the system;

[0039] an electric energy storage device, configured to store energy of the photovoltaic power generation device and supply energy when the photovoltaic power generation device outputs insufficiently;

[0040] a hydrogen energy storage device, configured to store energy of the photovoltaic power generation device, supply energy when the photovoltaic power generation device outputs insufficiently and provide hydrogen gas according to an equivalent state of charge of the hydrogen energy storage device;

[0041] the photovoltaic power generation device, the electric energy storage device, the hydrogen energy storage device and the load are connected through a direct current bus.

[0042] This invention introduces a preset control strategy to dynamically adjust the cutoff frequency of the low-pass filter based on the state of charge of the electric energy storage device, thereby achieving dynamic energy allocation for the storage and supply of energy by the electric and hydrogen energy storage devices. Simultaneously, an internal hydrogen flow regulation strategy is used to regulate the hydrogen flow in the hydrogen energy storage device, while an external hydrogen flow regulation strategy controls the hydrogen flow rate output from the hydrogen energy storage device. This invention can effectively control the state of charge of the electric energy storage device and the equivalent state of charge of the hydrogen energy storage device, preventing overcharging or over-discharging of the energy storage components. Attached Figure Description

[0043] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application. It is obvious that the drawings described below are merely some embodiments of this application, and those skilled in the art can obtain other drawings based on these drawings without any inventive effort. In the drawings:

[0044] Figure 1 This is a schematic flowchart of the photovoltaic microgrid control method provided in an embodiment of the present invention;

[0045] Figure 2 This is a schematic diagram of the structure of a photovoltaic microgrid provided in an embodiment of the present invention;

[0046] Figure 3 This is a flowchart illustrating the process of determining the operating mode of a photovoltaic microgrid, provided by an embodiment of the present invention.

[0047] Figure 4 This is a flowchart illustrating the adaptive power allocation strategy provided in an embodiment of the present invention;

[0048] Figure 5 This is a schematic flowchart of the hydrogen flow regulation strategy provided in an embodiment of the present invention;

[0049] Figure 6 This is a schematic diagram of the working process of the photovoltaic power generation device provided in the embodiments of the present invention;

[0050] Figure 7 This is a schematic diagram of a photovoltaic microgrid control device provided in an embodiment of the present invention;

[0051] Figure 8 This is a schematic diagram of the working process of the energy storage device provided in the embodiments of the present invention;

[0052] Figure 9 This is a schematic diagram of the fuel cell operation process of the hydrogen energy storage device provided in the embodiments of the present invention;

[0053] Figure 10This is a schematic diagram of the electrolyzer process of the hydrogen energy storage device provided in the embodiments of the present invention. Detailed Implementation

[0054] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention.

[0055] like Figure 8 This is a schematic diagram of the working process of the energy storage device provided in the embodiment of the present invention. Figure 9 This is a schematic diagram of the fuel cell operation process of the hydrogen energy storage device provided in the embodiments of the present invention. Figure 10 This is a schematic diagram of the electrolyzer process of the hydrogen energy storage device provided in the embodiments of the present invention.

[0056] Electric energy storage devices and hydrogen energy storage devices can operate in constant current (CC), constant voltage (CV), and off states. When both the electrical energy storage device and the hydrogen energy storage device in a photovoltaic microgrid are storing or supplying energy simultaneously, both devices operate in the CC (Cellular) state. Specifically, during energy storage, the electrolyzer of the hydrogen energy storage device operates in the CC state, while the fuel cell is in the OFF state. During energy supply, the electrolyzer of the hydrogen energy storage device is in the OFF state, and the fuel cell operates in the CC state. When both the equivalent state of charge (EFC) of the hydrogen energy storage device and the EFC of the electrical energy storage device reach their extreme values, both devices are in the OFF state. When only the electrical energy storage device in the photovoltaic microgrid is storing or supplying energy, it operates in the CV (Conversion Rate) state, and the hydrogen energy storage device is in the OFF state. Similarly, when only the hydrogen energy storage device in the photovoltaic microgrid is storing or supplying energy, it operates in the CV state, and the electrical energy storage device is in the OFF state. Specifically, during energy storage, the electrolyzer of the hydrogen energy storage device operates in the CV state, while the fuel cell is in the OFF state. During energy supply, the electrolyzer of the hydrogen energy storage device is in the OFF state, and the fuel cell operates in the CV state. Figure 8 , Figure 9 and Figure 10 The system further describes its underlying control over electrical and hydrogen energy storage devices.

[0057] like Figure 8 As shown, the reference current i for energy storage scref The current allocated to the energy storage device for storage or supply is, in this invention, the high-frequency current i allocated according to the adaptive power allocation strategy. eref i sc i represents the actual output current of the energy storage device. scconThis refers to the current that the energy storage device ultimately outputs to the DC bus. When the energy storage device operates in CC mode, i scref and i sc The proportional-integral (PI) controller generates the duty cycle of the converter, controlling the output i of the buck-boost converter. sccon To the DC bus; when the energy storage device is operating in CV mode, the bus reference voltage v busref and bus voltage v bus The bus reference current i is generated by the first PI controller. busref , and then with i sc The second PI controller generates a duty cycle to control the output i of the Buck-Boost converter. sccon To the DC bus. The current flow from the Buck-Boost converter to the DC bus is defined as positive, therefore, when the energy storage device stores energy... sccon When the value is negative, i is used when the energy storage device supplies power. sccon It is a positive value.

[0058] like Figure 9 As shown, the fuel cell reference current i fcref The current allocated to the hydrogen energy storage device and required to be supplied to the DC bus is, in this invention, the low-frequency current i allocated according to the adaptive power allocation strategy. href i fc This is the actual operating current of the fuel cell, i fccon This refers to the current that the fuel cell ultimately outputs to the DC bus. When the fuel cell operates in CC mode, i fcref and i fc The PI controller generates the duty cycle of the converter, which controls the output of the boost converter. fccon To the DC bus; when the fuel cell is operating in CV mode, v busref and v bus The bus reference current i is generated by the first PI controller. busref , and then with i fc The duty cycle of the Boost converter output i is generated by a second PI controller. fccon To the DC bus.

[0059] like Figure 10 As shown, the reference current i of the electrolytic cell elref The current allocated to the hydrogen energy storage device from the DC bus is, in this invention, the low-frequency current i allocated according to the adaptive power allocation strategy. href i el This is the actual operating current of the electrolytic cell, ielcon i represents the final output current from the electrolytic cell to the DC bus. elcon It is a negative value. When the electrolytic cell is operating in CC state, i elref and i el The duty cycle is generated by the PI controller, which controls the output i of the buck converter. elcon To the DC bus; when the electrolytic cell is operating in CV mode, v busref and v bus The bus reference current i is generated by the first PI controller. busref , and then with i el The second PI controller generates a duty cycle to control the output i of the Buck converter. elcon To the DC bus. In the above steps, the direction from the Buck converter to the DC bus is set to positive, therefore i elcon It is a negative value.

[0060] Please see Figures 1-7 It should be noted that the illustrations provided in this embodiment are only schematic representations of the basic concept of the present invention. Therefore, the illustrations only show the components related to the present invention and are not drawn according to the actual number, shape and size of the components in the actual implementation. In the actual implementation, the form, quantity and proportion of each component can be arbitrarily changed, and the layout of the components may also be more complex.

[0061] Figure 1 A schematic flowchart of the photovoltaic microgrid control method of the present invention is shown. Figure 2 This is a schematic diagram of the structure of a photovoltaic microgrid provided in an embodiment of the present invention.

[0062] The following will combine Figure 1 , Figure 2 The present invention will elaborate on the photovoltaic microgrid control method, wherein the photovoltaic microgrid includes: a photovoltaic power generation device 210, an electrical energy storage device 220, and a hydrogen energy storage device 230, and the method includes:

[0063] Step S110: Obtain the energy demand status of the photovoltaic microgrid, the state of charge of the electrical energy storage device 220, and the equivalent state of charge of the hydrogen energy storage device 230, and determine the operating mode of the photovoltaic microgrid.

[0064] In one embodiment, the step includes: if the energy demand state is in surplus and the state of charge is less than a preset maximum value and the equivalent state of charge is less than a preset maximum value, then the operating mode is the electro-hydrogen hybrid energy storage state; if the energy demand state is in deficit and the equivalent state of charge is greater than a preset minimum value and the state of charge is less than or equal to a preset minimum value, then the operating mode is the hydrogen energy supply state; if the energy demand state is in deficit and the state of charge is greater than the minimum value and the equivalent state of charge is greater than the minimum value, then the operating mode is the electro-hydrogen hybrid energy supply state.

[0065] Specifically, the power demand state of the photovoltaic microgrid is determined based on the output power of the photovoltaic power generation device 210 and the power required by the load 240 connected to the photovoltaic microgrid. The power state of the load 240, Pload, is compared with the power state of the photovoltaic power generation device 210, P... pv For comparison, if P load Less than P pv Then the energy demand state is in surplus; if P load Greater than P pv If the energy demand is insufficient, the energy demand state is in deficit. Based on the energy demand state, the state of charge (SOC) of the electrical energy storage device 220, and the equivalent state of charge (SOHC) of the hydrogen energy storage device 230, the operating mode of the photovoltaic microgrid can be determined. SOHC is the equivalent state of charge defined by analogy to electrical energy storage within the hydrogen energy storage device 230. Figure 3 The flowchart shown illustrates the process of determining the operating mode of a photovoltaic microgrid. When P1 oad Less than P pv That is, when the energy demand state is in surplus, the SOHC and the preset maximum equivalent state of charge SOHC will be adjusted. max For comparison, the SOC is compared with the preset maximum SOC. max Compare; if SOHC is less than SOHC max And SOC is less than SOC max The operating mode is a hybrid electro-hydrogen energy storage state; if SOHC is less than SOHC max And SOC is greater than or equal to SOC max The operating mode is hydrogen storage; if SOHC is greater than or equal to SOHC max And SOC is less than SOC max The operating mode is energy storage; if SOHC is greater than or equal to SOHC max And SOC is greater than or equal to SOC max If the operating mode is an energy surplus state, then energy exchange with the main power grid needs to be considered. When P1 oadGreater than or equal to P pv That is, when the energy demand state is in deficit, the SOHC and the preset minimum equivalent state of charge (SOHC) will be adjusted. min Compare the SOC with the preset minimum SOC. min Compare; if SOHC is greater than SOHC min And SOC is greater than SOC min The operating mode is a mixed electro-hydrogen power supply state; if SOHC is greater than SOHC min And SOC is less than or equal to SOC min The operating mode is hydrogen-powered; if SOHC is less than or equal to SOHC min And SOC is greater than SOC min The operating mode is electrically powered; if SOHC is less than or equal to SOHC min And SOC is less than or equal to SOC min If the operating mode is in a state of energy shortage, then energy exchange with the main power grid needs to be considered.

[0066] Step S120: When the working mode is the electric-hydrogen hybrid energy storage state or the electric-hydrogen hybrid energy supply state, the electric energy storage device 220 and the hydrogen energy storage device 230 are controlled to store or supply energy through a preset control strategy.

[0067] In one embodiment, the step includes: when the operating mode is the electro-hydrogen hybrid energy storage state or the electro-hydrogen hybrid energy supply state, adjusting the cutoff frequency of the low-pass filter through an adaptive power allocation strategy; when the operating mode is the electro-hydrogen hybrid energy storage state, allocating the high-frequency portion of the energy to the electro-hydrogen energy storage device 220 and the low-frequency portion of the energy to the hydrogen energy storage device 230 through the low-pass filter; when the operating mode is the electro-hydrogen hybrid energy supply state, enabling the electro-hydrogen energy storage device 220 to provide high-frequency energy and the hydrogen energy storage device 230 to provide low-frequency energy through the low-pass filter.

[0068] In one embodiment, the adaptive power allocation strategy includes: calculating a virtual artificial potential field based on the state of charge; and calculating the spectral area ratio and determining the cutoff frequency based on the current difference between the load 240 connected to the photovoltaic microgrid and the photovoltaic power generation device 210 and the virtual artificial potential field.

[0069] In one embodiment, the calculation of the virtual artificial potential field based on the state of charge is achieved by the following formula:

[0070]

[0071] Where F scLet sgn(x) be the virtual artificial potential field, sgn(x) be the step function, and SOC be the state of charge. max The maximum value of the state of charge, SOC min The minimum state of charge (SOC) is... mid And 'a' is a constant, and 'x' is the sum of SOC and SOC. mid The difference.

[0072] In one embodiment, the calculation of the spectral area ratio and determination of the cutoff frequency based on the current difference between the load 240 connected to the photovoltaic microgrid and the photovoltaic power generation device 210 and the virtual artificial potential field is achieved by the following formula:

[0073]

[0074] Where K sc It is the ratio of the spectrum area, sgn(x) is the step function, F sc It is the virtual artificial potential field, F scmid It is a constant that determines the power allocated to the energy storage device 220, i netload K is the current difference between the load 240 and the photovoltaic power generation device 210. sc Within the interval [0, 1].

[0075] Specifically, when the operating mode is a hybrid electric-hydrogen energy storage state or a hybrid electric-hydrogen energy supply state, both the electric energy storage device 220 and the hydrogen energy storage device 230 can store or supply energy. Therefore, it is necessary to allocate the energy stored or supplied by the two energy storage components to avoid overcharging or over-discharging of the energy storage components. This invention uses a preset control strategy for energy allocation. Specifically, an adaptive power allocation strategy dynamically adjusts the cutoff frequency of the low-pass filter based on the current SOC of the electric energy storage device 220. The low-pass filter then divides the energy to be stored or supplied into high-frequency and low-frequency components. The high-frequency component is stored or supplied by the electric energy storage device 220, and the low-frequency component is stored or supplied by the hydrogen energy storage device 230. The energy to be stored or supplied is the energy difference between the output energy of the photovoltaic power generation device 210 and the energy consumed by the load 240. Figure 4 The illustrated schematic diagram shows the adaptive power allocation strategy provided by the embodiment of the present invention. This strategy updates the cutoff frequency f of the LPF. c The current difference i between the load 240 and the photovoltaic power generation device 210 is decomposed using Fourier transform. netload Based on SOC, a virtual artificial potential field F is defined. sc Calculate the spectral area ratio K sc This allows for dynamic adjustment of the LPF cutoff frequency.

[0076] Virtual artificial potential field F scThe definition is as follows:

[0077]

[0078] Where F sc Let sgn(x) be the virtual artificial potential field, sgn(x) be the step function, and SOC be the state of charge. max The maximum value of the state of charge, SOC min The minimum state of charge (SOC) is... mid And 'a' is a constant, and 'x' is the sum of SOC and SOC. mid The difference.

[0079] Spectrum area ratio K sc The calculation formula is as follows:

[0080]

[0081] Where K sc It is the ratio of the spectrum area, sgn(x) is the step function, F sc It is the virtual artificial potential field, K scmid It is a constant that determines the power allocated to the energy storage device 220, i netload F is the current difference between the load 240 and the photovoltaic power generation device 210. sc It lies within the interval [0, 1]. Where, K... scmid The larger the value, the more power is allocated to the energy storage device 220.

[0082] like Figure 4 The current spectrum F in the figure sc For the portion allocated to the energy storage device 220, 1-K sc This portion is allocated to the hydrogen storage device 230. Bus reference voltage v busref and bus voltage v bus The bus reference current i is generated by a PI controller. busref i busref The LPF is then decomposed into low-frequency components i href and high frequency components i eref .

[0083] Step S130: When the working mode is the electric-hydrogen hybrid power supply state or the hydrogen power supply state, the hydrogen flow rate of the fuel cell 234 input to the hydrogen energy storage device 230 is controlled according to the internal hydrogen flow regulation strategy.

[0084] In one embodiment, this step is achieved by the following formula:

[0085]

[0086] Among them W fcIt is the hydrogen flow rate input to the fuel cell 234, i fc This is the actual operating current of the fuel cell 234, where R and F are constants, T is temperature, and N is... c This represents the number of individual cells in a fuel cell stack of 234, where z is the number of transferred electrons, and P... in η is the hydrogen pressure at the inlet of the fuel cell 234. cov It is the hydrogen conversion rate, η H It is the proportion of hydrogen in the fuel, i netload It is the current difference between the load 240 and the photovoltaic power generation device 210.

[0087] Specifically, in this embodiment, the hydrogen energy storage device 230 consists of a hydrogen storage tank 231, an electrolyzer 232, a Buck converter 233, a fuel cell 234, and a Boost converter 235. The Buck converter 233 is used to transfer surplus energy from the bus to the electrolyzer 232, and the Boost converter 235 is used to deliver the energy generated by the fuel cell 234 to the bus. When the operating mode is either an electric-hydrogen hybrid power supply state or a hydrogen power supply state, the hydrogen flow rate into the fuel cell 234 is controlled by an internal hydrogen flow regulation strategy to optimize the utilization rate of hydrogen in the fuel cell. Therefore, a fuel cell regulator is set between the hydrogen storage tank 231 and the fuel cell 234 to regulate the hydrogen flow rate W into the fuel cell 234. fc And it is achieved through the following formula:

[0088]

[0089] Among them W fc It is the hydrogen flow rate input to the fuel cell 234, i fc This is the actual operating current of the fuel cell 234, where R and F are constants, T is temperature, and N is... c This represents the number of individual cells in a fuel cell stack of 234, where z is the number of transferred electrons, and P... in η is the hydrogen pressure at the inlet of the fuel cell 234. cov It is the hydrogen conversion rate, η H It is the proportion of hydrogen in the fuel, i netload This is the current difference between the load 240 and the photovoltaic power generation device 210. It is understood that the fuel cell regulator and the fuel cell 234 are in the same switching state, i.e., SOHC is less than or equal to SOHC. min At that time, fuel cell 234 is in the off state, even if i netload When W is greater than or equal to 0, the fuel cell regulator is also in the off state. fc It is also 0.

[0090] In one embodiment, the method further includes: when the energy demand state is in surplus and the equivalent state of charge is greater than the minimum value of the equivalent state of charge, or when the energy demand state is in deficit and the equivalent state of charge is greater than a preset first reference value of the equivalent state of charge, controlling the hydrogen flow rate of the hydrogen energy storage device 230 to output hydrogen according to the external hydrogen flow regulation strategy.

[0091] In one embodiment, this step is achieved by the following formula:

[0092]

[0093] Among them W cp SOHC is the hydrogen flow rate output by the hydrogen energy storage device 230, W0 is the rated hydrogen flow rate into the compressor outside the hydrogen energy storage device 230, and α is the hydrogen flow rate. c and α s It is the tuning factor, ω c and ω s It is a constant, i netload It is the current difference between the load 240 and the photovoltaic power generation device 210, SOHC ref It is the first reference value of the equivalent state of charge.

[0094] Specifically, to ensure that SOHC is controlled within a certain range, this can be achieved by appropriately coordinating the hydrogen flow rates during the production, storage, and transportation stages. In this embodiment, the hydrogen refueling station 260 is connected to the hydrogen storage tank 231 via a transportation pipeline 250, and a compressor regulator and compressor for adjusting the hydrogen flow are provided between the hydrogen storage tank 231 and the transportation pipeline 250. When the energy demand state is in surplus and the equivalent state of charge (EFC) is greater than the minimum EFC value, or when the energy demand state is in deficit and the EFC is greater than a preset first reference value for the EFC, i.e., the hydrogen storage device 230 stores energy and the SOHC is greater than the minimum SOHC value, the hydrogen storage device 230 stores energy and the SOHC is greater than the minimum SOHC value. min Or, the hydrogen energy storage device 230 supplies power and the SOHC is greater than the preset first reference value SOHC. ref At this time, the hydrogen in the hydrogen storage tank 231 can be supplied to the outside through the compressor regulator according to the external hydrogen flow regulation strategy. The external hydrogen flow regulation strategy is achieved by the following formula:

[0095]

[0096] Among them W cp SOHC is the hydrogen flow rate output by the hydrogen energy storage device 230, W0 is the rated hydrogen flow rate into the compressor outside the hydrogen energy storage device 230, and α is the hydrogen flow rate. c and α c It is the tuning factor, ω c and ωs It is a constant, i netload It is the current difference between the load 240 and the photovoltaic power generation device 210, SOHC ref This is the first reference value for the equivalent state of charge. Where SOHC ref This is a reference value for the external hydrogen flow regulation strategy preset based on the performance of the hydrogen energy storage device 230, and SOHC ref greater than SOHC min When SOHC is less than or equal to SOHC min At the same time, the compressor regulator is also turned off.

[0097] In this embodiment, the investment and operating costs of the electrolyzer 232 and the fuel cell 234 are defined as C. hy The cost of the transport pipeline 250, which is related to the transmission distance and hydrogen capacity, is denoted as C. pip The specific formula is as follows:

[0098]

[0099] Where, η el It is the working efficiency of electrolytic cell 232, η fc It is the operating efficiency of fuel cell 234, G elin This refers to the purchase cost of electrolytic cell 232, C. fcin This refers to the purchase cost of fuel cell 234, L el This refers to the lifespan of electrolytic cell 232, L. fc This refers to the lifespan of fuel cell 234, C. elm The operating and maintenance cost of electrolytic cell 232, C fcm This refers to the operation and maintenance costs of fuel cell 234.

[0100] C pip =(C pipi n+C pipm +C tran ) l +m hy C cp

[0101] Among them, C pipin This is the depreciation cost of the 250 transport pipeline, C. pipm The maintenance cost of pipeline 250, C tran 1 represents the cost of transporting hydrogen via pipeline 250, and 1 represents the length of pipeline 250 in meters. hy It is the mass of hydrogen, C cp It refers to the compression cost of the compressor.

[0102] To ensure hydrogen is delivered to refueling stations even at high SOHC levels, and to keep the cost of the 250km transport pipeline reasonable, according to C... hyand C pip To define the tuning factor α c and α s Adjust the flow rate using the following formula:

[0103]

[0104] When C pip Higher than C hy At that time, due to the high transportation cost of hydrogen, α c This will lead to W cp Reduce; when the SOHC of the hydrogen storage tank is higher than the maximum SOHC value. max At that time, α s This will lead to W cp Increase the amount of hydrogen transferred from hydrogen storage tank 231.

[0105] Combination Figure 5 The illustrated embodiment of the present invention provides a schematic flowchart of a hydrogen flow regulation strategy, which includes the aforementioned internal hydrogen flow regulation strategy and external hydrogen flow regulation strategy. The hydrogen flow H in the hydrogen storage tank 231... 2_hst According to i fc W is output through the fuel cell regulator fc Through P in Input gas battery 234; can also output W via compressor regulator according to SOHC. cp The hydrogen pressure P' at the compressor inlet in Input compressor, where P' in With P in Equal in size, the compressor delivers W to the hydrogen refueling station 260 via transport pipeline 250. cp P out This refers to the hydrogen pressure at the compressor outlet. Additionally, the compressor consumes power P. load_cp P load_normal This indicates the power consumption of load 240, P load_cp With P load_normal The total load power consumption P of the photovoltaic microgrid load .

[0106] In one embodiment, the method further includes: when the state of charge is greater than or equal to a preset state of charge reference value or the equivalent state of charge is greater than or equal to a preset second equivalent state of charge reference value, controlling the photovoltaic power generation device 210 to reduce the output power.

[0107] Specifically, when the state of charge (SOC) is greater than or equal to a preset SOC reference value or an equivalent state of charge (ESC) greater than or equal to a preset second ESC reference value, to prevent the energy storage device 220 or the hydrogen energy storage device 230 from being unable to continue storing surplus energy, it is necessary to control the photovoltaic power generation device 210 to reduce its output power. The SOC reference value and the second ESC reference value are preset reference values ​​for photovoltaic control. Figure 6 The diagram shown illustrates the operation of a photovoltaic power generation device provided in an embodiment of the present invention. The photovoltaic power generation device 210 can operate in three states. When there is sufficient sunlight, the output current i pv and voltage v pv It operates in Maximum Power Point Tracking (MPPT) control mode; it operates in OFF mode during cloudy days or nights when sunlight is insufficient; when the SOC reaches the reference value or the SOHC reaches the second reference value, it operates according to v bus and v busref The converter duty cycle caused by the MPPT state is corrected by droop control to reduce photovoltaic output power. pvcon This refers to the current that is ultimately output to the DC bus.

[0108] It should be noted that the steps of the various methods described above are only for clarity. In practice, they can be combined into one step or some steps can be split 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 or introducing insignificant designs to the algorithm or process, but without changing the core design of the algorithm and process, are also within the scope of protection of this patent.

[0109] Combination Figure 7 The diagram shows a module schematic of a photovoltaic microgrid control device. The present invention also provides a photovoltaic microgrid control device 300, comprising:

[0110] The working mode determination module 310 is used to obtain the energy demand status of the photovoltaic microgrid, the state of charge of the electric energy storage device 220 and the equivalent state of charge of the hydrogen energy storage device 230, and determine the working mode of the photovoltaic microgrid.

[0111] The electric-hydrogen hybrid control module 320 is used to control the electric energy storage device 220 and the hydrogen energy storage device 230 to store or supply energy through a preset control strategy when the working mode is electric-hydrogen hybrid energy storage state or electric-hydrogen hybrid energy supply state.

[0112] The hydrogen flow coordination module 330 is used to control the hydrogen flow rate of the fuel cell 234 input to the hydrogen energy storage device 230 according to the internal hydrogen flow regulation strategy when the working mode is the electric hydrogen hybrid power supply state or the hydrogen power supply state.

[0113] It should be noted that the photovoltaic microgrid control device in this embodiment corresponds to the photovoltaic microgrid control method described above, and the functional modules in the photovoltaic microgrid control device correspond to the corresponding steps in the photovoltaic microgrid control method. The photovoltaic microgrid control device in this embodiment can be implemented in conjunction with the photovoltaic microgrid control method. Accordingly, the relevant technical details mentioned in the photovoltaic microgrid control device of this embodiment can also be applied to the photovoltaic microgrid control method described above.

[0114] It should be noted that the aforementioned functional modules can be fully or partially integrated into a single physical entity, or they can be physically separated. Furthermore, these modules can be implemented entirely in software via processing element calls; they can be fully implemented in hardware; or some modules can be implemented by processing element calls to software, while others are implemented in hardware. Additionally, these modules can be fully or partially integrated together, or implemented independently. The processing element mentioned here can be an integrated circuit with signal processing capabilities. In the implementation process, some or all of the steps of the above method, or the aforementioned functional modules, can be completed through integrated logic circuits in the hardware of the processor element or through software instructions.

[0115] Combination Figure 2 and Figure 7 As shown, the present invention also provides a photovoltaic microgrid control system, the system comprising:

[0116] Photovoltaic microgrid and photovoltaic microgrid control device 300;

[0117] The photovoltaic microgrid control device 300 is used to connect to and control the photovoltaic microgrid;

[0118] The photovoltaic microgrid includes:

[0119] Photovoltaic power generation device 210 is used to output energy to the load 240 connected to the photovoltaic microgrid and the system;

[0120] An energy storage device 220 is used to store the energy of the photovoltaic power generation device 210 and to provide energy when the output of the photovoltaic power generation device 210 is insufficient.

[0121] The hydrogen energy storage device 230 is used to store the energy of the photovoltaic power generation device 210, supply energy when the output of the photovoltaic power generation device 210 is insufficient, and supply hydrogen to the outside according to the equivalent state of charge of the hydrogen energy storage device 230.

[0122] The photovoltaic power generation device 210, the electric energy storage device 220, the hydrogen energy storage device 230, and the load 240 are connected via a DC bus.

[0123] like Figure 2 As shown, the photovoltaic microgrid includes a photovoltaic power generation device 210, an electrical energy storage device 220, and a hydrogen energy storage device 230, and is connected to a load 240. In this embodiment, the photovoltaic power generation device 210 includes a photovoltaic power generation device 211 and a Boost converter 212, which is used to transmit the energy generated by the photovoltaic power generation to the bus. The electrical energy storage device 220 includes a supercapacitor 221 and a Buck-Boost converter 222, where the supercapacitor 221 is used to absorb or provide energy. The hydrogen energy storage device 230 consists of a hydrogen storage tank 231, an electrolyzer 232, a Buck converter 233, a fuel cell 234, and a Boost converter 235. The Buck converter 233 is used to transfer surplus energy from the bus to the electrolyzer 232, and the Boost converter 235 is used to transmit the energy generated by the fuel cell 234 to the bus. In addition, in this embodiment of the invention, the hydrogen storage tank 231 is connected to a hydrogen refueling station 260 via a transport pipeline 250. The photovoltaic power generation device 210, the electrical energy storage device 220, the hydrogen energy storage device 230, and the load 240 are connected via a DC bus. For example... Figure 7 As shown, the photovoltaic microgrid control device 300 includes a working mode determination module 310, an electric-hydrogen hybrid control module 320, and a hydrogen flow coordination module 330. The photovoltaic microgrid control device 300 is connected to the photovoltaic microgrid and realizes control.

[0124] The photovoltaic microgrid control system provided in this embodiment is similar in principle to the photovoltaic microgrid control method and device of the present invention and includes all the basic features of the aforementioned photovoltaic microgrid control method and device.

[0125] This invention introduces a preset control strategy to dynamically adjust the cutoff frequency of the low-pass filter based on the state of charge of the electric energy storage device, thereby achieving dynamic energy allocation for the storage and supply of energy by the electric and hydrogen energy storage devices. Simultaneously, an internal hydrogen flow regulation strategy is used to regulate the hydrogen flow in the hydrogen energy storage device, while an external hydrogen flow regulation strategy controls the hydrogen flow rate output from the hydrogen energy storage device. This invention can effectively control the state of charge of the electric energy storage device and the equivalent state of charge of the hydrogen energy storage device, preventing overcharging or over-discharging of the energy storage components.

[0126] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the present invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the present invention.

[0127] The above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention.

Claims

1. A photovoltaic microgrid control method, characterized in that, The photovoltaic microgrid includes: a photovoltaic power generation device, an electrical energy storage device, and a hydrogen energy storage device; the method includes: The energy demand status of the photovoltaic microgrid, the state of charge of the electrical energy storage device, and the equivalent state of charge of the hydrogen energy storage device are obtained, and the operating mode of the photovoltaic microgrid is determined. When the working mode is a hybrid electric-hydrogen energy storage state or a hybrid electric-hydrogen energy supply state, the electric energy storage device and the hydrogen energy storage device are controlled to store or supply energy through a preset control strategy. When the working mode is the electric-hydrogen hybrid power supply state or the hydrogen power supply state, the hydrogen flow rate input to the fuel cell of the hydrogen energy storage device is controlled according to the internal hydrogen flow regulation strategy. The steps of obtaining the energy demand status of the photovoltaic microgrid, the state of charge of the electrical energy storage device, and the equivalent state of charge of the hydrogen energy storage device, and determining the operating mode of the photovoltaic microgrid, include: If the energy demand state is in surplus and the state of charge is less than the preset maximum state of charge and the equivalent state of charge is less than the preset maximum equivalent state of charge, then the working mode is the electric-hydrogen hybrid energy storage state. If the energy demand state is in deficit and the equivalent state of charge is greater than the preset minimum value of the equivalent state of charge, and the state of charge is less than or equal to the preset minimum value of the state of charge, then the working mode is the hydrogen power supply state. If the energy demand state is in deficit and the state of charge is greater than the minimum state of charge and the equivalent state of charge is greater than the minimum equivalent state of charge, then the working mode is the electric-hydrogen hybrid energy supply state. When the energy demand state is in surplus and the equivalent state of charge (EBC) is greater than the minimum EBC value, or when the energy demand state is in deficit and the EBC is greater than a preset first reference value for the EBC, the hydrogen flow rate of the hydrogen energy storage device is controlled according to an external hydrogen flow regulation strategy. This control of the hydrogen flow rate is achieved by the following formula: in This refers to the hydrogen flow rate output by the hydrogen energy storage device, and SOHC is the equivalent state of charge. The rated flow rate of hydrogen gas flowing into the compressor outside the hydrogen storage device. and It is an optimization factor. and It is a constant. It is the current difference between the load and the photovoltaic power generation device. It is the first reference value of the equivalent state of charge. It is greater than the minimum equivalent state of charge.

2. The photovoltaic microgrid control method according to claim 1, characterized in that, When the operating mode is a hybrid electric-hydrogen energy storage state or a hybrid electric-hydrogen energy supply state, the step of controlling the electric energy storage device and the hydrogen energy storage device to store or supply energy through a preset control strategy includes: When the operating mode is the electric-hydrogen hybrid energy storage state or the electric-hydrogen hybrid energy supply state, the cutoff frequency of the low-pass filter is adjusted through an adaptive power allocation strategy. When the working mode is the electric-hydrogen hybrid energy storage state, the high-frequency part of the energy is allocated to the electric energy storage device and the low-frequency part of the energy is allocated to the hydrogen energy storage device through the low-pass filter. When the operating mode is the hybrid electric-hydrogen energy supply state, the low-pass filter enables the electric energy storage device to provide high-frequency energy, and the hydrogen energy storage device to provide low-frequency energy.

3. The photovoltaic microgrid control method according to claim 2, characterized in that, The adaptive power allocation strategy includes: Calculate the virtual artificial potential field based on the stated state of charge; The spectrum area ratio is calculated and the cutoff frequency is determined based on the current difference between the load connected to the photovoltaic microgrid and the photovoltaic power generation device, and the virtual artificial potential field.

4. The photovoltaic microgrid control method according to claim 1, characterized in that, When the operating mode is the hybrid electric-hydrogen power supply state or the hydrogen power supply state, the hydrogen flow rate input to the fuel cell of the hydrogen energy storage device is controlled according to the internal hydrogen flow regulation strategy by the following formula: in It is the hydrogen flow rate input to the fuel cell. This is the actual operating current of the fuel cell. R and F It is a constant. T It's temperature. It refers to the number of individual cells contained in a fuel cell stack. z It is the number of electrons transferred. The hydrogen pressure at the fuel cell inlet. It is the hydrogen conversion rate. It refers to the proportion of hydrogen in the fuel. It is the current difference between the load and the photovoltaic power generation device.

5. The photovoltaic microgrid control method according to claim 1, characterized in that, The method further includes: When the state of charge is greater than or equal to a preset state of charge reference value or the equivalent state of charge is greater than or equal to a preset second equivalent state of charge reference value, the photovoltaic power generation device is controlled to reduce its output power.

6. A photovoltaic microgrid control device, characterized in that, include: The working mode determination module is used to obtain the energy demand status of the photovoltaic microgrid, the state of charge of the electric energy storage device, and the equivalent state of charge of the hydrogen energy storage device, and to determine the working mode of the photovoltaic microgrid. An electric-hydrogen hybrid control module is used to control the electric energy storage device and the hydrogen energy storage device to store or supply energy through a preset control strategy when the working mode is electric-hydrogen hybrid energy storage state or electric-hydrogen hybrid energy supply state. The hydrogen flow coordination module is used to control the hydrogen flow rate input to the fuel cell of the hydrogen energy storage device according to the internal hydrogen flow regulation strategy when the working mode is the electric-hydrogen hybrid power supply state or the hydrogen power supply state. The steps of obtaining the energy demand status of the photovoltaic microgrid, the state of charge of the electrical energy storage device, and the equivalent state of charge of the hydrogen energy storage device, and determining the operating mode of the photovoltaic microgrid, include: If the energy demand state is in surplus and the state of charge is less than the preset maximum state of charge and the equivalent state of charge is less than the preset maximum equivalent state of charge, then the working mode is the electric-hydrogen hybrid energy storage state. If the energy demand state is in deficit and the equivalent state of charge is greater than the preset minimum value of the equivalent state of charge, and the state of charge is less than or equal to the preset minimum value of the state of charge, then the working mode is the hydrogen power supply state. If the energy demand state is in deficit and the state of charge is greater than the minimum state of charge and the equivalent state of charge is greater than the minimum equivalent state of charge, then the working mode is the electric-hydrogen hybrid energy supply state. When the energy demand state is in surplus and the equivalent state of charge (EBC) is greater than the minimum EBC value, or when the energy demand state is in deficit and the EBC is greater than a preset first reference value for the EBC, the hydrogen flow rate of the hydrogen energy storage device is controlled according to an external hydrogen flow regulation strategy. This control of the hydrogen flow rate is achieved by the following formula: in This refers to the hydrogen flow rate output by the hydrogen energy storage device, and SOHC is the equivalent state of charge. The rated flow rate of hydrogen gas flowing into the compressor outside the hydrogen storage device. and It is an optimization factor. and It is a constant. It is the current difference between the load and the photovoltaic power generation device. It is the first reference value of the equivalent state of charge. It is greater than the minimum equivalent state of charge.

7. A photovoltaic microgrid control system, characterized in that, include: Photovoltaic microgrids and the photovoltaic microgrid control device according to claim 6; The photovoltaic microgrid control device is used to connect to and control the photovoltaic microgrid; The photovoltaic microgrid includes: A photovoltaic power generation device is used to output energy to the loads connected to the photovoltaic microgrid; An energy storage device is used to store the energy of the photovoltaic power generation device and to supply energy when the output of the photovoltaic power generation device is insufficient. A hydrogen energy storage device is used to store the energy of the photovoltaic power generation device, supply energy when the output of the photovoltaic power generation device is insufficient, and supply hydrogen to the outside according to the equivalent state of charge of the hydrogen storage device. The photovoltaic power generation device, the electrical energy storage device, the hydrogen energy storage device, and the load are connected via a DC bus.

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