Network construction type energy storage control method and device for smooth switching of micro-grid state, equipment and medium

Abstract

The invention is suitable for the technical field of micro-grid control, and provides a grid construction type energy storage control method and device for smooth switching of micro-grid states, equipment and a medium, and the method comprises the steps: sampling the interconnection line interaction power of a micro-grid side and a power distribution network side as virtual unbalanced power; calculating a voltage phase deviation value of a grid-connected point before and after switching from a grid-connected state to an off-grid state of the micro-grid based on the virtual unbalanced power, and dynamically calculating an energy storage active power pre-compensation value in combination with a damping integral response module and a second-order negative feedback loop; and iteratively correcting the phase angle through a power angle balance mechanism until the state switching constraint condition of the micro-grid is met. According to the technical scheme provided by the invention, active power output is actively adjusted through network construction type energy storage, voltage phase deviation caused by unbalanced power of a tie line is compensated, the voltage phase difference between the two sides of the micro-grid and the power distribution network is remarkably reduced, voltage phase synchronization during grid-connected to off-grid switching of the micro-grid is realized, and the grid-connected to off-grid switching of the micro-grid is realized. And the reliability and the stability of state switching of the micro-grid are improved.

Description

Technical Field

[0001] This application belongs to the technical field of microgrid control, and particularly relates to a grid-forming energy storage control method, device, equipment and medium for smooth switching of microgrid states. Background Technique

[0002] In the new power system, as a flexible distributed energy management system, the microgrid can operate independently in grid-connected mode and off-grid mode, with high energy utilization efficiency and environmental friendliness. However, during the process of the microgrid transitioning from the grid-connected state to the off-grid state, due to the significant deviation that may exist between the voltage phases on the microgrid side and the distribution network side, it often leads to switching failures and even causes system instability problems. Therefore, how to effectively control the voltage phase deviation and ensure the smoothness of the microgrid grid-connected and off-grid state switching is an important research topic at present.

[0003] Traditional microgrid control methods are mostly based on passive control strategies, that is, mainly relying on the rapid response of the microgrid's own energy storage system to maintain grid stability. However, this method is difficult to effectively compensate for the voltage phase deviation caused by the unbalanced power of the tie line. Especially when the transmission power of the tie line changes significantly, there is a risk of switching failure. In addition, the existing control methods usually ignore the problem of voltage phase synchronization between the two ends of the microgrid and the distribution network during the switching process, which greatly reduces the switching performance.

[0004] Therefore, how to improve the reliability and stability of microgrid state switching has become an urgent problem to be solved. Summary of the Invention

[0005] The embodiments of this application provide a grid-forming energy storage control method, device, equipment and medium for smooth switching of microgrid states, aiming to improve the reliability and stability of microgrid state switching.

[0006] In a first aspect, an embodiment of the present application provides a grid-forming energy storage control method for smooth switching of the microgrid state. The method includes: S1, sampling the interactive power of the connection line between the microgrid side and the distribution network side at time t as the first virtual unbalanced power; S2, based on the first virtual unbalanced power, calculating the voltage phase deviation amount of the grid connection point before and after the microgrid switches from the grid-connected state to the islanded state; S3, based on the voltage phase deviation amount, determining the active power set value of the grid-forming energy storage on the microgrid side; S4, based on the active power set value, calculating the first voltage phase angle of the grid connection point after the energy storage power is output on the microgrid side, and based on the voltage phase deviation amount and the first voltage phase angle, calculating the second voltage phase angle of the grid connection point after the energy storage power is output on the microgrid side at time t + 1; S5, calculating the target phase angle difference between the second voltage phase angle and the voltage phase angle of the grid connection point on the distribution network side, and based on the target phase angle difference and the preset microgrid grid-connected to islanded state switching constraint conditions, performing the microgrid grid-connected to islanded operation to achieve the consistency of the voltage phase angles at both ends of the microgrid side and the distribution network side when switching from the grid-connected state to the islanded state.

[0007] In a possible implementation manner, step S2 includes: using the absolute value of the first virtual unbalanced power as the input signal, and calculating the voltage phase deviation amount of the grid connection point before and after the microgrid switches from the grid-connected state to the islanded state by using a proportional-integral response module, and feeding back the voltage phase deviation amount to the grid-forming energy storage phase pre-synchronization link.

[0008] In a possible implementation manner, step S3 includes: based on the voltage phase deviation amount, calculating the active power pre-compensation amount required for the grid-forming energy storage on the microgrid side through a damping integral response module that resists voltage phase changes; and determining the active power set value of the grid-forming energy storage based on the rated power of the energy storage and the active power pre-compensation amount.

[0009] In a possible implementation manner, in step S4, the calculating the first voltage phase angle of the grid connection point after the energy storage power is output on the microgrid side based on the active power set value includes: in the active power phase conversion link of the grid-forming energy storage, calculating the target power deviation amount between the active power set value and the sampled value of the energy storage power output; and calculating the first voltage phase angle through a power angle balance second-order negative feedback loop of the power deviation amount and the voltage phase amount.

[0010] In a possible implementation manner, calculating the second voltage phase angle of the grid connection point after the energy storage power output on the microgrid side at the moment t + 1 based on the voltage phase deviation amount and the first voltage phase angle in step S4 includes: in the active power phase conversion link of the grid-forming energy storage, feeding back and superimposing the voltage phase deviation amount to the first voltage phase angle to correct the active power output by the grid-forming energy storage, so as to obtain the second voltage phase angle of the grid connection point after the energy storage power output on the microgrid side at the moment t + 1.

[0011] In a possible implementation manner, the preset microgrid grid-connected / off-grid state switching constraint conditions include that the voltage phase angle difference between the grid connection point on the distribution network side and the microgrid side is less than the maximum phase angle allowed for the microgrid to operate off-grid. The operation of switching the microgrid from grid-connected to off-grid based on the target phase angle difference and the preset microgrid grid-connected / off-grid state switching constraint conditions in step S5 includes: when the target phase angle difference is less than the maximum phase angle allowed for the microgrid to operate off-grid, the microgrid controller issues a grid-connected-to-off-grid switching command, and based on the grid-connected-to-off-grid switching command, controls the disconnection of the tie switch between the microgrid and the distribution network; when the target phase angle difference is greater than or equal to the maximum phase angle allowed for the microgrid to operate off-grid, repeat step S4 until the target phase angle difference is less than the maximum phase angle allowed for the microgrid to operate off-grid, then the microgrid controller issues the grid-connected-to-off-grid switching command, and based on the grid-connected-to-off-grid switching command, controls the disconnection of the tie switch between the microgrid and the distribution network.

[0012] In a possible implementation manner, step S5 further includes: sampling the interactive power of the tie line between the microgrid side and the distribution network side at the moment t + 1 as the second virtual unbalanced power; determining the identification value of the power deviation flag bit based on the second virtual unbalanced power and the preset power deviation threshold of the microgrid grid-connected / off-grid state; determining the identification value of the phase deviation flag bit based on the target phase angle difference and the maximum phase angle allowed for the microgrid to operate off-grid; determining the identification value of the mode switching flag bit for the microgrid grid-connected / off-grid based on the identification value of the power deviation flag bit and the identification value of the phase deviation flag bit; and performing the microgrid grid-connected / off-grid operation based on the identification value of the mode switching flag bit for the microgrid grid-connected / off-grid.

[0013] In a second aspect, an embodiment of the present application provides a grid-forming energy storage control device for smooth state switching of a microgrid. The device includes: a data acquisition module for sampling the interactive power of the connection line between the microgrid side and the distribution network side at time t as the first virtual unbalanced power; a first calculation module for calculating the voltage phase deviation amount of the grid connection point before and after the microgrid switches from the grid-connected state to the islanded state based on the first virtual unbalanced power; a second calculation module for determining the set value of the active power of the grid-forming energy storage on the microgrid side based on the voltage phase deviation amount; a third calculation module for calculating the first voltage phase angle of the grid connection point after the energy storage power is output on the microgrid side based on the set value of the active power, and calculating the second voltage phase angle of the grid connection point after the energy storage power is output on the microgrid side at time t + 1 based on the voltage phase deviation amount and the first voltage phase angle; a state switching control module for calculating the target phase angle difference between the second voltage phase angle and the voltage phase angle of the grid connection point on the distribution network side, and performing the operation of switching the microgrid from the grid-connected state to the islanded state based on the target phase angle difference and the preset microgrid grid-connected and islanded state switching constraint conditions, so as to achieve the consistency of the voltage phase angles at both ends of the microgrid side and the distribution network side when switching from the grid-connected state to the islanded state.

[0014] In a third aspect, an embodiment of the present application provides an electronic device, including a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, the method described in the first aspect or any one of its implementation manners is implemented.

[0015] In a fourth aspect, an embodiment of the present application provides a computer-readable storage medium storing a computer program, and when the computer program is executed by a processor, the method described in the first aspect or any one of its implementation manners is implemented.

[0016] In a fifth aspect, an embodiment of the present application provides a computer program product including a computer program, and when the computer program is executed by a processor, the steps of the method described in the first aspect or any one of its implementation manners are implemented.

[0017] The beneficial effects of the embodiments of the present application compared with the prior art are as follows: Extract the interactive power of the connection line between the microgrid side and the distribution network side and convert it into virtual unbalanced power. Calculate the voltage phase deviation based on the virtual unbalanced power, dynamically adjust the set value of the active power of the energy storage based on the voltage phase deviation, and then compensate for the voltage phase deviation caused by the unbalanced power of the connection line between the microgrid and the distribution network by actively adjusting the output power of the network-forming energy storage, significantly reducing the deviation of the voltage phase between the two ends of the microgrid and the distribution network, ensuring the consistency of the voltage phase angles at both ends of the microgrid side and the distribution network side when switching from the grid-connected state to the off-grid state, achieving precise synchronization of the voltage phase, avoiding the problem of failure in the switching of the microgrid connection and disconnection states due to excessive voltage phase deviation between the two sides, and improving the reliability and stability of the microgrid state switching.

[0018] It can be understood that a network-forming energy storage control device, an electronic device, a computer-readable storage medium, and a computer program product for smooth switching of the microgrid state provided by the embodiments of the present application have the same beneficial effects as the above-mentioned network-forming energy storage control method for smooth switching of the microgrid state, which will not be elaborated here. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following will briefly introduce the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings in the following description are only some embodiments of the present application. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0020] Figure 1 It is a schematic flowchart of a network-forming energy storage control method for smooth switching of the microgrid state provided by an embodiment of the present application; Figure 2 It is a schematic flowchart of another network-forming energy storage control method for smooth switching of the microgrid state provided by an embodiment of the present application; Figure 3 It is a schematic diagram of the voltage phase deviation between the two ends of the microgrid and the distribution network in the grid-connected to off-grid state provided by an embodiment of the present application; Figure 4 It is a schematic diagram of the interactive power of the connection line between the microgrid side and the distribution network side in the grid-connected to off-grid state provided by an embodiment of the present application; Figure 5 It is a structural block diagram of a network-forming energy storage control device for smooth switching of the microgrid state provided by an embodiment of the present application; Figure 6 It is a schematic structural diagram of an electronic device provided by an embodiment of the present application. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0021] In the following description, for purposes of illustration and not limitation, specific details such as specific system architectures, technologies, etc. are set forth in order to provide a thorough understanding of embodiments of the present application. However, those skilled in the art should appreciate that the present application may be implemented in other embodiments without these specific details. In other instances, detailed descriptions of well-known systems, devices, circuits, and methods are omitted so as not to obscure the description of the present application with unnecessary details.

[0022] It should be understood that when used in the specification of the present application and the appended claims, the term "comprising" indicates the presence of the described features, integers, steps, operations, elements, and / or components, but does not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or their combinations.

[0023] It should also be understood that the term "and / or" as used in the specification of the present application and the appended claims refers to any combination and all possible combinations of one or more of the associated listed items, and includes these combinations.

[0024] As used in the specification of the present application and the appended claims, the term "if" may be construed, depending on the context, as "when" or "once" or "in response to determining" or "in response to detecting". Similarly, the phrase "if determined" or "if detected [the described condition or event]" may be construed, depending on the context, as meaning "once determined" or "in response to determining" or "once detected [the described condition or event]" or "in response to detecting [the described condition or event]".

[0025] In addition, in the description of the specification of the present application and the appended claims, the terms "first", "second", "third", etc. are used only for distinguishing descriptions and should not be construed as indicating or implying relative importance.

[0026] Reference to "one embodiment" or "some embodiments" or the like described in the specification of the present application means that a specific feature, structure, or characteristic described in connection with that embodiment is included in one or more embodiments of the present application. Thus, statements such as "in one embodiment", "in some embodiments", "in other some embodiments", "in still other embodiments", etc. that appear in different places in this specification are not necessarily all referring to the same embodiment, but mean "one or more but not all embodiments", unless otherwise specifically emphasized in another way. The terms "comprising", "including", "having", and their variants all mean "including but not limited to", unless otherwise specifically emphasized in another way.

[0027] For ease of understanding, the technical solutions of the present application will be described in detail below in conjunction with the accompanying drawings.

[0028] Figure 1 Schematic diagram of the process of a grid-forming energy storage control method for smooth switching of the microgrid state provided by an embodiment of the present application, Figure 2 Schematic diagram of the process of another grid-forming energy storage control method for smooth switching of the microgrid state provided by an embodiment of the present application. For the sake of illustration, only the parts related to this embodiment are shown, such as Figure 1 and Figure 2 As shown, the method provided by this embodiment includes the following steps: S1, Sampling the interactive power of the connection line between the microgrid side and the distribution network side at time t as the first virtual unbalanced power.

[0029] In a specific implementation, the microgrid side includes a data acquisition unit, a grid-forming energy storage, distributed power sources, and loads, etc. The data acquisition unit collects the energy storage output power, distributed power source output power, and in-microgrid power consumption load power in the microgrid at time t, and takes the sum of the energy storage output power in the microgrid at time t and the difference between the distributed power source output power and the in-microgrid power consumption load power as the interactive power of the connection line between the microgrid side and the distribution network side at time t.

[0030] As an example, the interactive power of the connection line between the microgrid side and the distribution network side at time t, that is, the first virtual unbalanced power The calculation formula is: , wherein, is the distributed power source output power in the microgrid at time t, is the in-microgrid power consumption load power at time t, is the energy storage output power in the microgrid at time t.

[0031] Exemplarily, the distributed power source output power in the microgrid at time t is 15 kilowatts (kW), the in-microgrid power consumption load power at time t is 20 kW; the energy storage output power in the microgrid at time t is 0 kW.

[0032] S2, Based on the first virtual unbalanced power, calculate the voltage phase deviation amount at the grid connection point before and after the microgrid switches from the grid-connected state to the islanded state.

[0033] In a possible implementation manner, taking the absolute value of the first virtual unbalanced power as the input signal, using a proportional-integral response module to calculate the voltage phase deviation amount at the grid connection point before and after the microgrid switches from the grid-connected state to the islanded state, and feeding back the voltage phase deviation amount to the grid-forming energy storage phase pre-synchronization link.

[0034] In a specific implementation, the voltage phase deviation calculation module of the microgrid controller uses the first virtual unbalanced power Taking the absolute value as the input signal, a proportional-integral response module is used to calculate the voltage phase deviation of the grid connection point before and after the switching of the microgrid between grid-connected and islanded states , and feed it back to the phase pre-synchronization link of the grid-forming energy storage

[0035] As an example, the voltage phase deviation of the grid connection point before and after the switching of the microgrid between grid-connected and islanded states The calculation formula is as follows: , where represents the response time constant of the power change with respect to the voltage phase change; , represent the proportional coefficient and the integral coefficient respectively; s represents a complex variable in the Laplace transform, used for the conversion from time-domain analysis of the system to complex-frequency-domain analysis of the system

[0036] Exemplarily, during the calculation process takes a value of 0.1, takes a value of 10, takes a value of 0.5

[0037] S3. Based on the voltage phase deviation, determine the active power set value of the grid-forming energy storage on the microgrid side

[0038] In a possible implementation, based on the voltage phase deviation, calculate the required active power pre-compensation amount of the grid-forming energy storage on the microgrid side through a damping integral response module that resists voltage phase changes; based on the rated power of the energy storage and the active power pre-compensation amount, determine the active power set value of the grid-forming energy storage

[0039] In specific implementation, the grid-forming energy storage controller takes the voltage phase deviation , and through a damping integral response module that resists voltage phase changes, calculates the required active power pre-compensation amount of the grid-forming energy storage, and uses the rated power of the energy storage to superimpose the active power pre-compensation amount as the active power set value of the grid-forming energy storage .

[0040] As an example, the calculation formula of the active power pre-compensation amount and the calculation formula of the active power set value are respectively: , where , represent the response time constants of the phase change and the active power increase amount, represents the damping coefficient against the phase change amount, is the voltage phase deviation amount, is the rated power of the energy storage, and s represents a complex variable in the Laplace transform, which is used for the conversion from time-domain analysis of the system to complex-frequency-domain analysis of the system.

[0041] Exemplarily, during the calculation, takes a value of 0.1, takes a value of 0.2, takes a value of 5.

[0042] S4. Based on the active power set value, calculate the first voltage phase angle at the grid connection point after the energy storage power output on the microgrid side. Based on the voltage phase deviation amount and the first voltage phase angle, calculate the second voltage phase angle at the grid connection point after the energy storage power output on the microgrid side at time t + 1.

[0043] In a possible implementation manner, in step S4, calculating the first voltage phase angle at the grid connection point after the energy storage power output on the microgrid side based on the active power set value includes: in the active power phase conversion link of the grid-forming energy storage, calculating the target power deviation amount between the active power set value and the sampled value of the energy storage power output; based on the target power deviation amount, calculating the first voltage phase angle through the power angle balance second-order negative feedback loop of the power deviation amount and the voltage phase amount.

[0044] In a possible implementation manner, in step S4, calculating the second voltage phase angle at the grid connection point after the energy storage power output on the microgrid side at time t + 1 based on the voltage phase deviation amount and the first voltage phase angle includes: in the active power phase conversion link of the grid-forming energy storage, feedback-superimposing the voltage phase deviation amount on the first voltage phase angle to correct the active power output by the grid-forming energy storage, and obtaining the second voltage phase angle at the grid connection point after the energy storage power output on the microgrid side at time t + 1.

[0045] In specific implementation, in the active power phase conversion link of the grid-forming energy storage, the grid-forming energy storage controller calculates the active power set value and the sampled value of the energy storage power output to obtain the target power deviation amount therebetween, and calculates the first voltage phase angle at the grid connection point after the energy storage power output through the power angle balance second-order negative feedback loop of the power deviation amount and the voltage phase amount , and further feedback-superimposes the voltage phase deviation amount on the first voltage phase angle to correct the active power output by the grid-forming energy storage, and obtain the second voltage phase angle at the grid connection point after the energy storage power output on the microgrid side at time t + 1 .

[0046] As an example, the first voltage phase angle Calculation formula and second voltage phase angle The calculation formula is as follows: , wherein, , respectively represent the set value of the energy storage active power at time t and the sampled value of the energy storage power output; J and D respectively represent the inertia coefficient and damping coefficient of the second-order power angle balance link; , respectively represent the voltage amplitudes at the grid connection point on the distribution network side and the microgrid side; X represents the line impedance connecting the microgrid and the distribution network, represents the rated angular frequency of the microgrid operation, and s represents a complex variable in the Laplace transform, which is used for the conversion from the time-domain analysis system to the complex-frequency domain analysis system.

[0047] Exemplarily, during the calculation process, the value of J is 0.5, the value of D is 20, and the value of X is 0.005.

[0048] S5. Calculate the target phase angle difference between the second voltage phase angle and the voltage phase angle at the grid connection point on the distribution network side, and based on the target phase angle difference and the preset microgrid grid-connected to islanded state switching constraint conditions, perform the microgrid grid-connected to islanded operation to achieve the consistency of the voltage phase angles at both ends of the microgrid side and the distribution network side when switching from the grid-connected state to the islanded state.

[0049] In a possible implementation manner, the preset microgrid grid-connected to islanded state switching constraint conditions include that the voltage phase angle difference between the grid connection point on the distribution network side and the microgrid side is less than the maximum phase angle allowed for the microgrid islanded operation. In step S5, based on the target phase angle difference and the preset microgrid grid-connected to islanded state switching constraint conditions, performing the microgrid grid-connected to islanded operation includes: when the target phase angle difference is less than the maximum phase angle allowed for the microgrid islanded operation, the microgrid controller issues a grid-connected to islanded switching instruction, and based on the grid-connected to islanded switching instruction, controls the disconnection of the tie switch between the microgrid and the distribution network; when the target phase angle difference is greater than or equal to the maximum phase angle allowed for the microgrid islanded operation, repeat step S4 until the target phase angle difference is less than the maximum phase angle allowed for the microgrid islanded operation, and then the microgrid controller issues a grid-connected to islanded switching instruction, and based on the grid-connected to islanded switching instruction, controls the disconnection of the tie switch between the microgrid and the distribution network.

[0050] In a possible implementation, step S5 further includes: sampling the interactive power of the connection line between the microgrid side and the distribution network side at time t+1 as the second virtual unbalanced power; determining the identification value of the power deviation flag bit based on the second virtual unbalanced power and the preset power deviation threshold for the grid-connected to islanding state of the microgrid; determining the identification value of the phase deviation flag bit based on the target phase angle difference and the maximum phase angle allowed for the microgrid to operate in islanding mode; determining the identification value of the mode switching flag bit for the grid-connected to islanding of the microgrid based on the identification value of the power deviation flag bit and the identification value of the phase deviation flag bit; and performing the grid-connected to islanding operation of the microgrid based on the identification value of the mode switching flag bit for the grid-connected to islanding of the microgrid.

[0051] In a specific implementation, when the second virtual unbalanced power is less than the preset power deviation threshold for the grid-connected to islanding state of the microgrid, determine that the identification value of the power deviation flag bit is 1; when the second virtual unbalanced power is greater than or equal to the preset power deviation threshold for the grid-connected to islanding state of the microgrid, determine that the identification value of the power deviation flag bit is 0; when the target phase angle difference is less than the maximum phase angle allowed for the microgrid to operate in islanding mode, determine that the identification value of the phase deviation flag bit is 1; when the target phase angle difference is greater than or equal to the maximum phase angle allowed for the microgrid to operate in islanding mode, determine that the identification value of the phase deviation flag bit is 0; the identification value of the mode switching flag bit for the grid-connected to islanding of the microgrid is the result of the intersection of the identification value of the power deviation flag bit and the identification value of the phase deviation flag bit. The identification value of the mode switching flag bit for the grid-connected to islanding of the microgrid includes 1 and 0. When the identification value of the mode switching flag bit for the grid-connected to islanding of the microgrid is 0, it means that the connection switch between the microgrid and the distribution network does not perform the grid-connected to islanding operation. When the identification value of the mode switching flag bit for the grid-connected to islanding of the microgrid is 1, it means that the connection switch between the microgrid and the distribution network performs the grid-connected to islanding operation.

[0052] As an example, the calculation method of the mode switching flag bit S for the grid-connected to islanding of the microgrid is: , where, represents the maximum power phase angle allowed for the microgrid to operate in islanding mode; and represent the power deviation flag bit and the phase deviation flag bit respectively; represents the preset power deviation threshold for the grid-connected to islanding state of the microgrid; represents the second virtual unbalanced power, represents the target phase angle difference, , represents the voltage phase angle of the grid connection point on the distribution network side at time t+1, represents the second voltage phase angle.

[0053] Exemplarily, during the calculation process, The value of is 0.2,

[0054] It should be noted that the maximum power phase angle allowed for the microgrid to operate in the off-grid mode and the preset power deviation threshold for the microgrid to switch from the grid-connected state to the off-grid state can be customized according to the actual situation, and this application does not make any limitations in this regard.

[0055] As another example, the power deviation flag bit can also be determined by the first virtual unbalanced power to determine.

[0056] Exemplarily, when the first virtual unbalanced power is equal to 0, the identification value of the power deviation flag bit is 1, and when the first virtual unbalanced power is not equal to 0, the identification value of the power deviation flag bit is 0.

[0057] As an example, Figure 3 and Figure 4 are respectively the schematic diagrams of the voltage phase deviation between the microgrid and the distribution network in the grid-connected to off-grid state and the interactive power of the connection line between the microgrid side and the distribution network side in the grid-connected to off-grid state after adopting the technical solution provided by this application. As shown in Figure 3 and Figure 4 shown, the voltage phase deviation between the microgrid and the distribution network in the grid-connected to off-grid state and the interactive power of the connection line between the microgrid side and the distribution network side in the grid-connected to off-grid state both finally approach 0.

[0058] The technical solution provided by this application extracts the interactive power of the connection line between the microgrid side and the distribution network side and converts it into virtual unbalanced power, calculates the voltage phase deviation amount based on this virtual unbalanced power, dynamically adjusts the set value of the energy storage active power based on the voltage phase deviation amount, and then compensates for the voltage phase deviation caused by the unbalanced power of the microgrid-distribution network connection line by actively adjusting the output power of the grid-forming energy storage, significantly reducing the deviation of the voltage phase between the microgrid and the distribution network, ensuring the consistency of the voltage phase angles at both ends of the microgrid side and the distribution network side during the grid-connected to off-grid state, realizing the precise synchronization of the voltage phase, avoiding the problem of the failure of the microgrid grid-connected to off-grid state switching caused by too large voltage phase deviation on both sides, and improving the reliability and stability of the microgrid state switching.

[0059] Figure 5 It is the structural block diagram of a grid-forming energy storage control device for smooth switching of the microgrid state provided by an embodiment of this application. For the convenience of description, only the parts related to the embodiment of this application are shown. Refer to Figure 5, the grid-forming energy storage control device 500 for smooth switching of the microgrid state may include a data acquisition module 501, a first calculation module 502, a second calculation module 503, a third calculation module 504, and a state switching control module 505.

[0060] The data acquisition module 501 is configured to sample the interactive power of the connection line between the microgrid side and the distribution network side at time t as the first virtual unbalanced power.

[0061] The first calculation module 502 is configured to calculate the voltage phase deviation amount of the grid connection point before and after the state switching of the microgrid from grid-connected to islanded based on the first virtual unbalanced power.

[0062] The second calculation module 503 is configured to determine the active power set value of the grid-forming energy storage on the microgrid side based on the voltage phase deviation amount.

[0063] The third calculation module 504 is configured to calculate the first voltage phase angle of the grid connection point after the energy storage power output on the microgrid side based on the active power set value, and calculate the second voltage phase angle of the grid connection point after the energy storage power output on the microgrid side at time t + 1 based on the voltage phase deviation amount and the first voltage phase angle.

[0064] The state switching control module 505 is configured to calculate the target phase angle difference between the second voltage phase angle and the voltage phase angle of the grid connection point on the distribution network side, and perform the operation of switching the microgrid from grid-connected to islanded based on the target phase angle difference and the preset microgrid grid-connected to islanded state switching constraint conditions, so as to achieve the consistency of the voltage phase angles at both ends of the microgrid side and the distribution network side during the grid-connected to islanded state switching.

[0065] The grid-forming energy storage control device for smooth switching of the microgrid state provided by the embodiments of the present application has the same beneficial effects as the above-mentioned grid-forming energy storage control method for smooth switching of the microgrid state.

[0066] It should be noted that the information interaction, execution process, etc. between the above-mentioned device / units, due to being based on the same concept as the method embodiments of the present application, for their specific functions and the technical effects brought, reference can be specifically made to the method embodiment part, and details are not described herein again.

[0067] Those skilled in the art can clearly understand that, for the convenience and conciseness of description, only the above division of each functional unit and module is used as an example. In actual applications, the above functions can be allocated to different functional units and modules according to needs, that is, the internal structure of the device is divided into different functional units or modules to complete all or part of the functions described above. Each functional unit and module in the embodiment can be integrated in a processing unit, or each unit can exist physically alone, or two or more units can be integrated in one unit. The above integrated unit can be implemented in the form of hardware or in the form of a software functional unit. In addition, the specific names of each functional unit and module are only for the convenience of mutual distinction and do not limit the protection scope of this application. The specific working processes of the units and modules in the above system can refer to the corresponding processes in the foregoing method embodiments and will not be elaborated herein.

[0068] Figure 6 FIG. is a schematic structural diagram of an electronic device provided in an embodiment of the present application. As Figure 6 shown, the electronic device 6 in this embodiment includes: at least one processor 60 ( Figure 6 only one is shown in the figure), a memory 61, and a computer program 62 stored in the memory 61 and executable on at least one processor 60. When the processor 60 executes the computer program 62, it implements the above Figure 1 or Figure 2 steps in the method embodiment, or implements the functions of each module / unit in the above Figure 5 device embodiment.

[0069] The electronic device 6 can be a computing device such as a desktop computer, a notebook, a palm computer, and a cloud server. The electronic device 6 may include but is not limited to the processor 60 and the memory 61. Those skilled in the art can understand that Figure 6 merely an example of the electronic device 6, which does not constitute a limitation on the electronic device 6, and may include more or fewer components than shown in the figure, or combine some components, or different components. For example, it may also include input / output devices, network access devices, etc.

[0070] The processor 60 may be a Central Processing Unit (CPU), or it may also be other general-purpose processors, Digital Signal Processors (DSPs), Application Specific Integrated Circuits (ASICs), Field-Programmable Gate Arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. The general-purpose processor may be a microprocessor or any conventional processor, etc.

[0071] In some embodiments, the memory 61 may be an internal storage unit of the electronic device 6, such as the hard disk or memory of the electronic device 6. In other embodiments, the memory 61 may also be an external storage device of the electronic device 6, such as a plug-in hard disk, Smart Media Card (SMC), Secure Digital (SD) card, Flash Card, etc. equipped on the electronic device 6. Further, the memory 61 may also include both the internal storage unit and the external storage device of the electronic device 6. The memory 61 is used to store an operating system, application programs, a BootLoader, data, and other programs, such as the program code of a computer program. The memory 61 may also be used to temporarily store data that has been output or is to be output.

[0072] The embodiments of the present application also provide a computer-readable storage medium storing a computer program, and when the computer program is executed by a processor, the steps in the above method embodiments can be implemented.

[0073] When the integrated unit is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, to implement all or part of the processes in the above method embodiments of this application, a computer program can be used to instruct the relevant hardware to complete. The computer program can be stored in a computer-readable storage medium. When the computer program is executed by a processor, the steps of the above method embodiments can be implemented. Among them, the computer program includes computer program code, and the computer program code can be in the form of source code, object code, executable file or some intermediate form, etc. The computer-readable medium can at least include: any entity or device that can carry the computer program code to an electronic device, a recording medium, a computer memory, a read-only memory (ROM, Read-Only Memory), a random access memory (RAM, Random Access Memory), an electrical carrier signal, a telecommunication signal, and a software distribution medium. For example, a USB flash drive, a mobile hard disk, a magnetic disk or an optical disc, etc.

[0074] A computer-readable storage medium provided by an embodiment of this application has the same beneficial effects as the above method for controlling a grid-forming energy storage for smooth switching of a microgrid state.

[0075] An embodiment of this application provides a computer program product. The computer program product includes a computer program. When the computer program is executed by a processor, the steps in the above method embodiments can be implemented.

[0076] A computer program product provided by an embodiment of this application has the same beneficial effects as the above method for controlling a grid-forming energy storage for smooth switching of a microgrid state.

[0077] In the above embodiments, the descriptions of each embodiment have their own emphases. For the parts not detailed or recorded in a certain embodiment, reference can be made to the relevant descriptions of other embodiments.

[0078] Those of ordinary skill in the art can realize that the units and algorithm steps of each example described in combination with the embodiments disclosed in this document can be implemented by electronic hardware, or by a combination of computer software and electronic hardware. Whether these functions are executed in a hardware or software manner depends on the specific application and design constraints of the technical solution. A professional technician can use different methods to implement the described functions for each specific application, but this implementation should not be considered to exceed the scope of this application.

[0079] In the embodiments provided in the present application, it should be understood that the disclosed apparatus / devices and methods can be implemented in other ways. For example, the apparatus / device embodiments described above are merely illustrative. For example, the division of the modules or units is only a logical function division. In actual implementation, there may be other division methods. For example, multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the displayed or discussed couplings or direct couplings or communication connections between each other can be through some interfaces. The indirect couplings or communication connections of the devices or units can be in electrical, mechanical or other forms.

[0080] The units described as separate components may or may not be physically separated. The components displayed as units may or may not be physical units, that is, they can be located in one place or distributed to multiple network units. Some or all of the units can be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0081] The above embodiments are only used to illustrate the technical solutions of the present application and are not intended to limit them. Although the present application has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements for some of the technical features. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present application, and should all be included in the protection scope of the present application.

Claims

1. A microgrid state smooth switching grid-type energy storage control method, characterized in that: The method comprises: S1, sampling time t, the interaction power of the tie line between the microgrid side and the distribution network side is taken as the first virtual unbalanced power; S2, based on the first virtual unbalanced power, calculating the voltage phase deviation of the grid connection point before and after the microgrid is switched from grid connection to off-grid state; S3, based on the voltage phase deviation, determining the active power setting value of the microgrid-side grid-type energy storage; S4, based on the active power setting value, calculating the first voltage phase angle of the grid connection point after the microgrid side energy storage power is output, and based on the voltage phase deviation and the first voltage phase angle, calculating the second voltage phase angle of the grid connection point after the microgrid side energy storage power is output at time t+1; S5, calculate the target phase angle difference between the second voltage phase angle and the voltage phase angle of the grid-connected point on the distribution network side, and based on the target phase angle difference and the preset microgrid on-grid and off-grid state switching constraints, execute the microgrid on-grid to off-grid operation to achieve consistency of the voltage phase angles at both ends of the microgrid side and the distribution network side when the on-grid state is switched to the off-grid state.

2. The method according to claim 1, characterized in that Step S2 comprises: The absolute value of the first virtual unbalanced power is used as an input signal, and a proportional-integral response module is used to calculate the voltage phase deviation of the grid-connected point before and after the microgrid is switched from grid-connected to off-grid state, and the voltage phase deviation is fed back to the grid-connected energy storage phase pre-synchronization link.

3. The method according to claim 1, characterized in that Step S3 includes: Based on the voltage phase deviation, the active power pre-compensation amount required for the microgrid-side grid-type energy storage is calculated through a damped integral response module that resists voltage phase changes; Based on the energy storage rated power and the active power pre-compensation amount, the active power setting value of the grid-connected energy storage is determined.

4. The method according to claim 1, characterized in that: The step S4, based on the active power setting value, calculates the first voltage phase angle of the grid connection point after the energy storage power is output on the microgrid side, including: In the active phase conversion link of the grid-forming energy storage, the target power deviation between the active power setting value and the energy storage power output sampling value is calculated; Based on the target power deviation, the first voltage phase angle is calculated through a power angle balance second-order negative feedback loop of the power deviation and the voltage phase.

5. The method according to claim 1, characterized in that The step S4, based on the voltage phase deviation and the first voltage phase angle, calculates the second voltage phase angle of the grid connection point after the microgrid side energy storage power is output at time t+1, including: In the active phase conversion link of the grid-forming energy storage, the voltage phase deviation feedback is superimposed on the first voltage phase angle to correct the active power output by the grid-forming energy storage, and obtain the second voltage phase angle after the microgrid side energy storage power is output at the grid connection point at time t+1.

6. The method according to claim 1, characterized in that The preset microgrid on-grid and off-grid state switching constraint condition includes that the voltage phase angle difference between the grid connection point on the distribution network side and the microgrid side is less than the maximum phase angle allowed for the off-grid operation of the microgrid. The microgrid on-grid to off-grid operation is performed based on the target phase angle difference and the preset microgrid on-grid and off-grid state switching constraint condition in step S5, including: When the target phase angle difference is less than the maximum phase angle allowed for the off-grid operation of the microgrid, the microgrid controller issues a grid-to-off-grid switching instruction, and controls the connection switch between the microgrid and the distribution network to be disconnected based on the grid-to-off-grid switching instruction; When the target phase angle difference is greater than or equal to the maximum phase angle allowed for the off-grid operation of the microgrid, step S4 is repeated until the target phase angle difference is less than the maximum phase angle allowed for the off-grid operation of the microgrid, and the microgrid controller issues the grid-to-off-grid switching instruction, and controls the connecting switch between the microgrid and the distribution network to disconnect based on the grid-to-off-grid switching instruction.

7. The method according to claim 6, characterized in that Step S5 further includes: The interactive power of the tie line between the microgrid side and the distribution network side at sampling time t+1 is used as the second virtual unbalanced power; Determine a power deviation flag value based on the second virtual unbalanced power and a preset power deviation threshold of the microgrid grid-connected to off-grid state; Determine a phase deviation flag value based on the target phase angle difference and the maximum phase angle allowed for off-grid operation of the microgrid; Based on the power deviation flag bit identification value and the phase deviation flag bit identification value, determine the mode switching flag bit identification value of the microgrid grid-connected to off-grid mode; Based on the microgrid on-grid to off-grid mode switching flag value, the microgrid on-grid to off-grid operation is performed.

8. A microgrid state smooth switching grid-type energy storage control device, characterized in that: The device comprises: A data acquisition module, used for sampling the interactive power of the tie line between the microgrid side and the distribution network side at time t as the first virtual unbalanced power; A first calculation module is used to calculate the voltage phase deviation of the grid connection point before and after the microgrid is switched from grid connection to off-grid state based on the first virtual unbalanced power; A second calculation module is used to determine the active power setting value of the microgrid-side grid-type energy storage based on the voltage phase deviation; A third calculation module is used to calculate the first voltage phase angle of the grid connection point after the microgrid side energy storage power is output based on the active power setting value, and calculate the second voltage phase angle of the grid connection point after the microgrid side energy storage power is output at time t+1 based on the voltage phase deviation and the first voltage phase angle; The state switching control module is used to calculate the target phase angle difference between the second voltage phase angle and the voltage phase angle of the grid-connected point on the distribution network side, and based on the target phase angle difference and the preset microgrid on-grid and off-grid state switching constraint conditions, execute the microgrid on-grid to off-grid operation to achieve consistency of the voltage phase angles at both ends of the microgrid side and the distribution network side when the on-grid state is switched to the off-grid state.

9. An electronic device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that: When the processor executes the computer program, the method according to any one of claims 1 to 7 is implemented.

10. A computer-readable storage medium storing a computer program, characterized in that: When the computer program is executed by a processor, the method according to any one of claims 1 to 7 is implemented.

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