Power network grid-type energy storage device SOC self-maintenance control method and system

Abstract

The present invention discloses a self-maintenance control method and system for the SOC of a grid-type energy storage device in a power network. The method comprises: respectively obtaining the SOCs of a plurality of grid-type energy storage devices; when the SOC of any grid-type energy storage device is greater than an upper limit value of a normal operating range or less than a lower limit value of a normal operating range, reassigning a standard frequency-corresponding output power value of the grid-type energy storage device via an energy storage device converter, controlling the grid-type energy storage device to enter a self-maintenance state, wherein the frequency value of the energy storage device converter changes with the reassigned standard frequency-corresponding output power value, driving the output power changes of other grid-type energy storage devices in the power network, and further driving the output power changes of the grid-type energy storage device; and when the SOC of the grid-type energy storage device is adjusted to within the normal operating range with the output power change, restoring the standard frequency-corresponding output power value to the initial standard frequency-corresponding power value.

Description

Technical Field

[0001] The present invention relates to the field of power networks, and in particular to a method and system for self-maintenance control of a SOC (State of Charge) (SOC) of a power network-type energy storage device. Background Art

[0002] With the rapid growth of renewable energy generation, the contradiction between large-scale development and efficient utilization of renewable energy is becoming increasingly prominent. While benefiting from the sustainability, cleanliness, and low carbon advantages of renewable energy, new power systems, primarily based on renewable energy, are also challenged by their inherent uncertainties and low inertia. The investment and deployment of energy storage can effectively address the high uncertainty and low inertia issues faced by power systems with high renewable energy penetration. However, traditional energy storage participation in grid dispatch primarily involves receiving dispatch control commands and adjusting power accordingly. With the gradual implementation of incentives for clean energy and green electricity consumption, and the increasing development of regional autonomous energy grids and local power grids, the use of energy storage as a voltage source to participate in or lead grid frequency and voltage regulation is becoming a trend. Electrochemical energy storage systems utilize a power storage converter (PCS) for bidirectional power transmission, while batteries for energy release and storage. When energy storage operates as the primary power source, the energy margin of the storage battery, in addition to the PCS power margin, becomes a crucial indicator of grid sustainability. Therefore, maintaining the state of charge (SOC) of the storage battery is crucial for improving power supply reliability. Because power changes in grid-type energy storage are closely related to grid frequency deviations, when the energy storage SOC needs maintenance, the state of charge of the energy storage battery is often adjusted by switching from a voltage source to a power source mode. This energy storage SOC maintenance method weakens the power regulation autonomy of the grid-type energy storage. In addition, the superior control system corresponding to the PCS formulates control strategies based on the safety, stability, and economy of the regional energy autonomous grid or local grid. If the influence of energy storage SOC constraints and changes in the PCS working mode of the grid-type energy storage device converter are always considered in the strategy formulation, the control strategy branches will increase, and there will be the possibility of repeatedly adjusting the grid-type energy storage droop coefficient, thereby increasing the computational complexity and strategy complexity of the power adjustment and allocation of the superior dispatching system, and reducing the consistency and smoothness of the control strategy of the entire system. Summary of the Invention

[0003] The purpose of the embodiments of the present invention is to provide a self-maintenance control method and system for the SOC of a grid-type energy storage device in an electric power network. By improving the continuity of the control strategy of a regional energy autonomous power grid or a local power grid, the expansion of the grid frequency fluctuation range and duration caused by the lack of smoothness in switching the control strategy is reduced, thereby ensuring the stability of the regional energy autonomous power grid, especially the local power grid containing multi-point grid-type energy storage operating in parallel.

[0004] To solve the above technical problems, a first aspect of an embodiment of the present invention provides a method for self-maintaining the SOC of a grid-type energy storage device in a power network. The power network includes a plurality of grid-type energy storage devices operating in parallel at multiple points. The plurality of grid-type energy storage devices are connected to the power network via energy storage device converters. The control method includes the following steps:

[0005] Obtain the SOC of several grid-type energy storage devices respectively;

[0006] When the SOC of any of the grid-type energy storage devices is greater than the upper limit of the normal operating range or less than the lower limit of the normal operating range, the output power value corresponding to the standard frequency of the grid-type energy storage device is reassigned through the energy storage device converter to control the grid-type energy storage device to enter a self-maintenance state;

[0007] In the self-maintenance state, the frequency value of the energy storage device converter changes with the re-assigned output power value, driving the output power of other grid-type energy storage devices in the power network to change, and further driving the output power of the grid-type energy storage device to change;

[0008] When the SOC of the grid-type energy storage device is adjusted to a normal operating range along with the output power change, the output power value corresponding to the standard frequency is restored to the initial power value corresponding to the standard frequency.

[0009] Furthermore, the re-assigned standard frequency corresponding output power value is calculated according to the following formula:

[0010] P1=λ×k 最优 ×C×V 直 ;

[0011] Wherein, P1 is the output power value corresponding to the standard frequency of the re-assigned grid-type energy storage device, λ is the charge and discharge coefficient, when the grid-type energy storage device is charged, λ=+1, when the grid-type energy storage device is discharged, λ=-1, k 最优 is the battery characteristic coefficient, C is the ampere-hour value of the capacity of the grid-type energy storage device, V 直 is the total terminal voltage of the grid-type energy storage device.

[0012] Furthermore, the power network type energy storage device SOC self-maintenance control method further includes:

[0013] When the current grid-type energy storage device is in the self-maintenance state, if the SOC of any other grid-type energy storage device is also greater than the upper limit value of the normal operating range or less than the lower limit value of the normal operating range, the other grid-type energy storage device is controlled to enter the self-maintenance state.

[0014] Furthermore, after controlling the other grid-type energy storage devices to enter the self-maintenance state, the method further includes:

[0015] If the charge and discharge status of the current grid-type energy storage device is consistent with the charge and discharge status of other grid-type energy storage devices, the output power value corresponding to the standard frequency of the current grid-type energy storage device is reassigned until the self-maintenance directions of the current grid-type energy storage device and the other grid-type energy storage devices are consistent with their respective SOC adjustment directions.

[0016] Furthermore, the power network type energy storage device SOC self-maintenance control method further includes:

[0017] When any of the grid-type energy storage devices is in a self-maintenance state, detecting a real-time frequency value of the power network;

[0018] If the real-time frequency value exceeds a preset frequency range, an alarm message is sent to a superior dispatching system of the power network.

[0019] Furthermore, the power network type energy storage device SOC self-maintenance control method further includes:

[0020] Detecting a real-time voltage value and a real-time frequency value of the energy storage device converter in a self-maintenance state;

[0021] When the ratio of the difference between the real-time voltage value and the standard voltage value to the standard voltage value is greater than a first preset ratio, the grid-type energy storage device is controlled to exit the self-maintenance state, and the output power value corresponding to the standard frequency of the energy storage device converter is restored to the initial power value corresponding to the standard frequency; or

[0022] When the difference between the real-time frequency value and the standard frequency value is greater than the first preset frequency value, the grid-type energy storage device is controlled to exit the self-maintenance state, and the output power value corresponding to the standard frequency of the energy storage device converter is restored to the initial power value corresponding to the standard frequency.

[0023] Furthermore, after controlling the grid-type energy storage device to exit the self-maintenance state, the method further includes:

[0024] After a preset time period, determining whether the real-time frequency value or the real-time frequency value has returned to a normal value;

[0025] If so, the grid-type energy storage device is controlled to re-enter the self-maintenance state.

[0026] Furthermore, the power network includes: a regional energy autonomous power grid or a local power grid.

[0027] Accordingly, a second aspect of an embodiment of the present invention provides a self-maintaining control system for a SOC of a grid-type energy storage device in a power network, wherein the power network includes a plurality of grid-type energy storage devices operating in parallel at multiple points, wherein the plurality of grid-type energy storage devices are connected to the power network via energy storage device converters, and the control system includes:

[0028] A state acquisition module, which is used to respectively obtain the SOC of several grid-type energy storage devices;

[0029] a power assignment module configured to reassign the output power value corresponding to the standard frequency of the grid-type energy storage device through the energy storage device converter when the SOC of the grid-type energy storage device is greater than the upper limit of the normal operating range or less than the lower limit of the normal operating range, thereby controlling the grid-type energy storage device to enter a self-maintenance state;

[0030] In the self-maintenance state, the frequency value of the energy storage device converter changes with the re-assigned output power value corresponding to the standard frequency, driving the output power of other grid-type energy storage devices in the power network to change, and further driving the output power of the grid-type energy storage device to change;

[0031] A power recovery module is used to restore the output power value corresponding to the standard frequency to the initial power value corresponding to the standard frequency when the SOC of the grid-type energy storage device is adjusted to a normal operating range along with the output power change.

[0032] Accordingly, a third aspect of an embodiment of the present invention provides an electronic device comprising: at least one processor; and a memory connected to the at least one processor; wherein the memory stores instructions that can be executed by the at least one processor, and the instructions are executed by the at least one processor so that the at least one processor executes the above-mentioned power network grid-type energy storage device SOC self-maintenance control method.

[0033] Accordingly, a fourth aspect of an embodiment of the present invention provides a computer-readable storage medium having computer instructions stored thereon, which, when executed by a processor, implement the above-mentioned SOC self-maintenance control method for a power network-type energy storage device.

[0034] The above technical solutions of the embodiments of the present invention have the following beneficial technical effects:

[0035] 1. The energy storage SOC maintenance function is implemented locally by the PCS of the grid-type energy storage device converter, without relying on the communication network or requiring superior dispatch instructions, thus increasing the autonomy and reliability of its SOC maintenance function.

[0036] 2. The control strategy adopted by the superior dispatching system does not need to constantly consider the SOC maintenance of the grid-type energy storage device, and there is no need to make repeated adjustments for the SOC maintenance of the grid-type energy storage device. This ensures the coherence and consistency of the control strategy, reduces the amount of calculation and strategy branches, and increases the overall reliability of the control system.

[0037] 3. The frequency adjustment caused by energy storage SOC maintenance is shared by all grid-connected power electronic equipment, which reduces the range of frequency fluctuations and ensures smooth transition of regional energy autonomous grid or local grid status. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 This is a flow chart of a method for controlling the SOC self-maintenance of a power network-type energy storage device according to an embodiment of the present invention;

[0039] Figure 2 is a schematic diagram of a power network architecture provided by an embodiment of the present invention;

[0040] Figure 3 This is a schematic diagram of the SOC self-maintenance process of a grid-type energy storage device provided by an embodiment of the present invention;

[0041] Figure 4 This is a block diagram of the SOC self-maintenance control system module of the power network grid-type energy storage device provided by an embodiment of the present invention.

[0042] Reference numerals:

[0043] 1. Status acquisition module, 2. Power assignment module, 3. Power recovery module. DETAILED DESCRIPTION

[0044] To make the objectives, technical solutions, and advantages of the present invention more clearly understood, the present invention will be further described in detail below in conjunction with specific embodiments and with reference to the accompanying drawings. It should be understood that these descriptions are merely exemplary and are not intended to limit the scope of the present invention. In addition, in the following description, descriptions of well-known structures and technologies are omitted to avoid unnecessary confusion of the concepts of the present invention.

[0045] Multi-point grid-connected energy storage devices together form the frequency and voltage active support system for a regional energy autonomous grid or local power grid. When the grid-connected energy storage devices are operating normally, the PCS converters of the energy storage devices adopt a voltage source control mode. The droop coefficient determines the change in power provided by each grid-connected energy storage device when the frequency changes, thereby allowing the system to reach a new steady state. The power value corresponding to the standard frequency determines the output of the grid-connected energy storage when the grid is in a state of no frequency deviation. This can be adjusted by the local or higher-level dispatching system based on real-time and future operating conditions.

[0046] Please refer to Figure 1A first aspect of an embodiment of the present invention provides a method for self-maintaining the SOC of a grid-type energy storage device in a power network. The power network includes a plurality of grid-type energy storage devices operating in parallel at multiple points. The plurality of grid-type energy storage devices are connected to the power network via energy storage device converters (PCSs). The control method includes the following steps:

[0047] Step S100 , respectively obtaining the SOCs of a plurality of grid-type energy storage devices.

[0048] The aforementioned power networks include regional energy autonomous grids or local power grids. Currently, these grids have multiple power sources, and their network architecture utilizes a multi-voltage source, multi-point distribution. The voltage sources include multiple energy storage converters using grid-type energy storage control technology, and the network operates in a multi-voltage source parallel mode.

[0049] Step S200: When the SOC of any grid-type energy storage device is greater than the upper limit of the normal operating range or less than the lower limit of the normal operating range, the output power value corresponding to the standard frequency of the grid-type energy storage device is reassigned through the energy storage device converter, and the grid-type energy storage device is controlled to enter a self-maintenance state.

[0050] In the self-maintenance state, the frequency value of the energy storage device converter changes with the output power value corresponding to the reassigned standard frequency, driving the output power changes of other grid-forming energy storage devices in the power network, and then driving the output power changes of the grid-forming energy storage device.

[0051] When the SOC of a grid-connected energy storage device in a regional energy autonomous grid or local power grid reaches the upper or lower limit of its normal operating range, the SOC self-maintenance function of that energy storage device is activated. At this point, the energy storage device's power converter (PCS) reassigns the initial power value (P0) corresponding to the standard frequency based on the optimal charge and discharge rate corresponding to the energy storage device's own battery capacity and characteristics. When the new value obtained by the PCS after reassigning P0 causes frequency fluctuations at the current point, the output of the remaining grid-connected power sources in the grid fluctuates due to the frequency fluctuations. This in turn causes the output of the energy storage device's power converter (PCS), which is performing SOC self-maintenance, to change in a direction that improves the energy storage battery's state of charge, and the frequency and power of the regional energy autonomous grid or local power grid also reach a new stable state. As charging (discharging) time passes, the energy storage device's SOC gradually recovers to the midpoint of the normal value range, at which point the original power value (P0) corresponding to the standard frequency is restored.

[0052] Step S300 , when the SOC of the grid-type energy storage device is adjusted to a normal operating range along with the output power change, the output power value corresponding to the standard frequency is restored to the initial power value corresponding to the standard frequency.

[0053] In the above technical solution, the power network architecture adopts a multi-voltage source multi-point distribution. The voltage source includes multiple energy storage converters that adopt grid-type energy storage control technology. The network operation mode is a multi-voltage source parallel operation mode. The initial corresponding power value P0 of the standard frequency corresponding to the standard frequency determines the output of the grid-type energy storage when the grid is in a state of no frequency deviation. The SOC self-maintenance control method of the grid-type energy storage device is to reassign the initial corresponding power value P0 of the standard frequency according to the optimal charge and discharge rate corresponding to the energy storage battery's own capacity and its own characteristics through the energy storage device converter PCS to perform battery SOC maintenance.

[0054] By improving the continuity of the regional energy autonomous power grid or local power grid control strategy, the expansion of the grid frequency fluctuation range and duration caused by the lack of smoothness in the switching of control strategies is reduced, ensuring the stability of the regional energy autonomous power grid, especially the local power grid that includes multi-point grid-type energy storage operating in parallel.

[0055] In a specific implementation of the embodiment of the present invention, the re-assigned standard frequency corresponding output power value is calculated according to the following formula:

[0056] P1=λ×k 最优 ×C×V 直 ;

[0057] Among them, P1 is the output power value corresponding to the standard frequency of the re-assigned grid-type energy storage device, λ is the charge and discharge coefficient, when the grid-type energy storage device is charging, λ=+1, when the grid-type energy storage device is discharging, λ=-1, k 最优 is the battery characteristic coefficient, C is the ampere-hour value of the grid-type energy storage device capacity, V 直 is the total terminal voltage of the grid-type energy storage device.

[0058] In addition, the SOC self-maintenance control method of the power network grid-type energy storage device also includes:

[0059] While the current grid-type energy storage device is in self-maintenance mode, if the SOC of any other grid-type energy storage device is also greater than the upper limit of the normal operating range or less than the lower limit of the normal operating range, the other grid-type energy storage devices will be controlled to enter self-maintenance mode. If the SOC of one grid-type energy storage device reaches the upper or lower limit of the normal operating range during SOC maintenance, the other grid-type energy storage devices will also be controlled to activate the SOC self-maintenance function.

[0060] Furthermore, after controlling other grid-type energy storage devices to enter the self-maintenance state, the method further includes:

[0061] If the charge and discharge status of the current grid-type energy storage device is consistent with the charge and discharge status of other grid-type energy storage devices, the output power value corresponding to the standard frequency of the current grid-type energy storage device is reassigned until the self-maintenance directions of the current grid-type energy storage device and the other grid-type energy storage devices are consistent with their respective SOC adjustment directions.

[0062] At this time, if other grid-type energy storage devices that have reached the limit of the normal operating range have the same maintenance direction as the previous grid-type energy storage device (both charging or discharging), it may affect the previous energy storage device converter PCS output change to the opposite direction of the SOC self-maintenance power. At this time, it is necessary to reassign the power value corresponding to the standard frequency of the previous grid-type energy storage device converter PCS until the power of the energy storage system requiring SOC self-maintenance is in the self-maintenance direction.

[0063] Furthermore, the SOC self-maintenance control method of the power network grid-type energy storage device also includes: when any grid-type energy storage device is in the self-maintenance state, detecting the real-time frequency value of the power network; if the real-time frequency value exceeds the preset frequency range, sending an alarm message to the upper-level dispatching system of the power network.

[0064] When the grid frequency exceeds the preset limit during the SOC maintenance of the grid-connected energy storage device, the superior dispatching system will make adjustments based on the non-grid-connected energy storage, new energy output status and controllable and adjustable load operation to restore the frequency to the allowable deviation range for normal operation.

[0065] Furthermore, the power network grid-type energy storage device SOC self-maintenance control method also includes: detecting the real-time voltage value and real-time frequency value of the energy storage device converter PCS in the self-maintenance state; when the ratio of the difference between the real-time voltage value and the standard voltage value to the standard voltage value is greater than a first preset ratio value, controlling the grid-type energy storage device to exit the self-maintenance state, and restoring the output power value corresponding to the standard frequency of the energy storage device converter PCS to the initial power value corresponding to the standard frequency; or, when the difference between the real-time frequency value and the standard frequency value is greater than a first preset frequency value, controlling the grid-type energy storage device to exit the self-maintenance state, and restoring the output power value corresponding to the standard frequency of the energy storage device converter PCS to the initial power value corresponding to the standard frequency.

[0066] During SOC maintenance for a grid-connected energy storage device, if the regional autonomous energy grid or local grid enters an emergency state, the PCS (Power Supply System) in the energy storage device performing SOC self-maintenance for the grid-connected energy storage device senses a sudden voltage or frequency change and automatically exits SOC maintenance, restoring the original initial power value, P0. If the grid voltage and frequency return to normal after 15 seconds, SOC self-maintenance continues. If the grid remains within its normal operating range, operating mode control is implemented according to commands from the superior dispatching system. At this point, there is a risk of the PCS exiting operation due to operating conditions or low SOC. When grid parameters return to the normal operating range, a new round of SOC self-maintenance for the grid-connected energy storage device is initiated when the SOC of the grid-connected energy storage device reaches the normal operating range limit again.

[0067] Furthermore, after controlling the grid-type energy storage device to exit the self-maintenance state, it also includes: after a preset time period, determining whether the real-time frequency value or the real-time frequency value has returned to a normal value; if so, controlling the grid-type energy storage device to re-enter the self-maintenance state.

[0068] During the SOC maintenance of the grid-type energy storage device, the superior dispatching system has the right to reassign P0 of the PCS that performs the SOC self-maintenance of the grid-type energy storage device.

[0069] Next, combine Figure 2 , the above control method is described in detail:

[0070] An example of a power network structure is Figure 2 As shown, it includes multi-voltage source multi-point distribution, such as the grid-type energy storage device 1, the grid-type energy storage device 2 and the grid-type energy storage device 3 in the figure, and the operation mode is multi-voltage source parallel operation mode. In the regional energy autonomous power grid or the local power grid, each grid-type energy storage device is connected to the power grid through the energy storage device converter PCS; in each regional energy autonomous power grid or the local power grid, it also includes at least one photovoltaic power generation device and at least one wind power generation device, each photovoltaic power generation device is connected to the power grid through a grid-connected inverter, and each wind power generation device is connected to the power grid through a converter, and each regional energy autonomous power grid or the local power grid is connected to a load device. The following steps are adopted:

[0071] Step 1: Real-time monitoring of the SOC of the grid-type energy storage device. When the SOC of a grid-type energy storage device in the regional energy autonomous grid or local grid reaches the warning limit (upper or lower limit), the SOC self-maintenance function of the grid-type energy storage device is activated.

[0072] Step 2: For the energy storage device converter PCS (such as the grid-type energy storage device 1) whose battery SOC reaches the warning limit, the standard frequency corresponding output power value P is calculated based on the optimal charge and discharge rate corresponding to the battery capacity and characteristics of the grid-type energy storage device 1. 0-1Reassignment of .

[0073] Step 3: The energy storage device converter PCS of the grid-type energy storage device 1 is 0-1 The new value causes the frequency fluctuation at the current point, so that the output of other grid-type power sources in the grid (such as grid-type energy storage device 2 and grid-type energy storage device 3) changes due to the frequency fluctuation, and then the output of the energy storage device converter PCS of the grid-type energy storage device 1 that performs self-maintenance of the energy storage device SOC changes.

[0074] Step 4: The SOC of the energy storage device of the grid-type energy storage device 1 reaches the median of the normal value range, and at this time, the original initial power value P of the energy storage device converter PCS of the grid-type energy storage device 1 is restored. 0-1 .

[0075] Specifically, when the SOC self-maintenance function of the grid-type energy storage device is used to control the P of the energy storage device converter PCS of the grid-type energy storage device 1, 0-1 After the assignment, when the grid frequency stabilizes and the PCS output power of the energy storage device converter and the battery SOC maintenance optimal charge and discharge power ratio is not calculated between 70% and 120%, the P 0-1 Reassign.

[0076] Accordingly, a second aspect of an embodiment of the present invention provides a self-maintaining control system for a grid-type energy storage device in a power network, wherein the power network includes a plurality of grid-type energy storage devices operating in parallel at multiple points, wherein the plurality of grid-type energy storage devices are connected to the power network via energy storage device converters, and the control system includes:

[0077] A state acquisition module 1 is used to respectively acquire the SOC of a plurality of grid-type energy storage devices;

[0078] Power assignment module 2, which is used to reassign the output power value corresponding to the standard frequency of the grid-type energy storage device through the energy storage device converter when the SOC of the grid-type energy storage device is greater than the upper limit of the normal operating range or less than the lower limit of the normal operating range, and control the grid-type energy storage device to enter the self-maintenance state;

[0079] In the self-maintenance state, the frequency value of the energy storage device converter changes with the output power value corresponding to the re-assigned standard frequency, driving the output power changes of other grid-forming energy storage devices in the power network, and further driving the output power changes of the grid-forming energy storage device;

[0080] The power recovery module 3 is used to restore the output power value corresponding to the standard frequency to the initial power value corresponding to the standard frequency when the SOC of the grid-type energy storage device is adjusted to a normal operating range along with the output power change.

[0081] Accordingly, a third aspect of an embodiment of the present invention provides an electronic device comprising: at least one processor; and a memory connected to the at least one processor; wherein the memory stores instructions that can be executed by the at least one processor, and the instructions are executed by the at least one processor so that the at least one processor executes the above-mentioned power network grid-type energy storage device SOC self-maintenance control method.

[0082] Accordingly, a fourth aspect of an embodiment of the present invention provides a computer-readable storage medium having computer instructions stored thereon, which, when executed by a processor, implement the above-mentioned SOC self-maintenance control method for a power network-type energy storage device.

[0083] The embodiment of the present invention aims to protect a self-maintenance control method and system for the SOC of a grid-type energy storage device in an electric power network, wherein the electric power network includes a plurality of grid-type energy storage devices operating in parallel at multiple points, and the plurality of grid-type energy storage devices are connected to the electric power network respectively through energy storage device converters, and the control method includes the following steps: obtaining the SOC of the plurality of grid-type energy storage devices respectively; when the SOC of any grid-type energy storage device is greater than the upper limit value of the normal operating range or less than the lower limit value of the normal operating range, the standard frequency corresponding output power value of the grid-type energy storage device is reassigned through the energy storage device converter, and the grid-type energy storage device is controlled to enter a self-maintenance state; in the self-maintenance state, the frequency value of the energy storage device converter changes with the reassigned standard frequency corresponding output power value, driving the output power change of other grid-type energy storage devices in the electric power network, and then driving the output power change of the grid-type energy storage device; when the SOC of the grid-type energy storage device is adjusted to the normal operating range with the output power change, the standard frequency corresponding output power value is restored to the initial corresponding power value of the standard frequency. The above technical solution has the following effects:

[0084] 1. The energy storage device SOC maintenance function is implemented locally by the energy storage device converter PCS, without relying on the communication network or requiring superior dispatch instructions, thus increasing the autonomy and reliability of its SOC maintenance function.

[0085] 2. The control strategy adopted by the superior dispatching system does not need to constantly consider the SOC maintenance of the grid-type energy storage device, and there is no need to make repeated adjustments for the SOC maintenance of the grid-type energy storage device. This ensures the coherence and consistency of the control strategy, reduces the amount of calculation and strategy branches, and increases the overall reliability of the control system.

[0086] 3. The frequency adjustment caused by energy storage SOC maintenance is shared by all grid-connected power electronic equipment, which reduces the range of frequency fluctuations and ensures smooth transition of regional energy autonomous grid or local grid status.

[0087] Those skilled in the art will appreciate that the embodiments of the present application can be provided as methods, systems, or computer program products. Therefore, the present application can adopt the form of a complete hardware embodiment, a complete software embodiment, or an embodiment in combination with software and hardware. Moreover, the present application can adopt the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to magnetic disk storage, CD-ROM, optical storage, etc.) that contain computer-usable program code.

[0088] The present application is described with reference to the flowcharts and / or block diagrams of the methods, devices (systems), and computer program products according to the embodiments of the present application. It should be understood that each process and / or box in the flowchart and / or block diagram, as well as the combination of the processes and / or boxes in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the steps in the process. Figure 1 a process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0089] These computer program instructions may also be stored in a computer readable memory that can direct a computer or other programmable data processing device to work in a specific manner, so that the instructions stored in the computer readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 a process or multiple processes and / or boxes Figure 1 The function specified in one or more boxes.

[0090] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operational steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing the instructions executed on the computer or other programmable device for implementing the process. Figure 1 a process or multiple processes and / or boxes Figure 1 A step that specifies a function in one or more boxes.

[0091] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, ordinary technicians in the field should understand that the specific implementation methods of the present invention can still be modified or replaced by equivalents. Any modification or equivalent replacement that does not depart from the spirit and scope of the present invention should be covered by the scope of protection of the claims of the present invention.

Claims

1. A method for self-maintenance control of SOC of a power network type energy storage device, characterized in that: The power network includes a plurality of grid-type energy storage devices operating in parallel at multiple points, wherein the plurality of grid-type energy storage devices are connected to the power network via energy storage device converters. The control method includes the following steps: Obtain the SOC of several grid-type energy storage devices respectively; When the SOC of any of the grid-type energy storage devices is greater than the upper limit of the normal operating range or less than the lower limit of the normal operating range, the output power value corresponding to the standard frequency of the grid-type energy storage device is reassigned through the energy storage device converter to control the grid-type energy storage device to enter a self-maintenance state; In the self-maintenance state, the frequency value of the energy storage device converter changes with the re-assigned output power value, driving the output power of other grid-type energy storage devices in the power network to change, and further driving the output power of the grid-type energy storage device to change; When the SOC of the grid-type energy storage device is adjusted to a normal operating range along with the output power change, the output power value corresponding to the standard frequency is restored to the initial power value corresponding to the standard frequency; The re-assigned standard frequency corresponding output power value is calculated according to the following formula: P1=λ×k 最优 ×C×V 直 ; Wherein, P1 is the output power value corresponding to the standard frequency of the re-assigned grid-type energy storage device, λ is the charge and discharge coefficient, when the grid-type energy storage device is charged, λ=+1, when the grid-type energy storage device is discharged, λ=-1, k 最优 is the battery characteristic coefficient, C is the ampere-hour value of the capacity of the grid-type energy storage device, V 直 is the total terminal voltage of the grid-type energy storage device.

2. The SOC self-maintenance control method of the power network type energy storage device according to claim 1 is characterized in that: Also includes: When the current grid-type energy storage device is in the self-maintenance state, if the SOC of any other grid-type energy storage device is greater than the upper limit value of the normal operating range or less than the lower limit value of the normal operating range, the other grid-type energy storage device is controlled to enter the self-maintenance state.

3. The SOC self-maintenance control method of the power network type energy storage device according to claim 2 is characterized in that: After controlling the other grid-type energy storage devices to enter the self-maintenance state, the method further includes: If the charge and discharge status of the current grid-type energy storage device is consistent with the charge and discharge status of other grid-type energy storage devices, the output power value corresponding to the standard frequency of the current grid-type energy storage device is reassigned until the self-maintenance directions of the current grid-type energy storage device and the other grid-type energy storage devices are consistent with their respective SOC adjustment directions.

4. The SOC self-maintenance control method of the power network type energy storage device according to claim 1 is characterized in that: Also includes: When any of the grid-type energy storage devices is in a self-maintenance state, detecting a real-time frequency value of the power network; If the real-time frequency value exceeds a preset frequency range, an alarm message is sent to a superior dispatching system of the power network.

5. The SOC self-maintenance control method of the power network type energy storage device according to claim 1, characterized in that: Also includes: Detecting a real-time voltage value and a real-time frequency value of the energy storage device converter in a self-maintenance state; When the ratio of the difference between the real-time voltage value and the standard voltage value to the standard voltage value is greater than a first preset ratio, the grid-type energy storage device is controlled to exit the self-maintenance state, and the output power value corresponding to the standard frequency of the energy storage device converter is restored to the initial power value corresponding to the standard frequency; or When the difference between the real-time frequency value and the standard frequency value is greater than the first preset frequency value, the grid-type energy storage device is controlled to exit the self-maintenance state, and the output power value corresponding to the standard frequency of the energy storage device converter is restored to the initial power value corresponding to the standard frequency.

6. The SOC self-maintenance control method of the power network type energy storage device according to claim 5 is characterized in that: After controlling the grid-type energy storage device to exit the self-maintenance state, the method further includes: After a preset time period, determining whether the real-time frequency value or the real-time frequency value has returned to a normal value; If so, the grid-type energy storage device is controlled to re-enter the self-maintenance state.

7. The SOC self-maintenance control method for a power network-type energy storage device according to any one of claims 1 to 6, characterized in that: The power network includes: a regional energy autonomous power grid or a local power grid.

8. A power network type energy storage device SOC self-maintenance control system, characterized in that: The SOC of a power network grid-type energy storage device is controlled based on the SOC self-maintenance control method of any one of claims 1 to 7, wherein the power network includes a plurality of grid-type energy storage devices operating in parallel at multiple points, and the plurality of grid-type energy storage devices are respectively connected to the power network via energy storage device converters, and the control system includes: A state acquisition module, which is used to respectively obtain the SOC of several grid-type energy storage devices; a power assignment module configured to reassign the output power value corresponding to the standard frequency of the grid-type energy storage device through the energy storage device converter when the SOC of the grid-type energy storage device is greater than the upper limit of the normal operating range or less than the lower limit of the normal operating range, thereby controlling the grid-type energy storage device to enter a self-maintenance state; In the self-maintenance state, the frequency value of the energy storage device converter changes with the re-assigned output power value, driving the output power of other grid-type energy storage devices in the power network to change, and further driving the output power of the grid-type energy storage device to change; A power recovery module is used to restore the output power value corresponding to the standard frequency to the initial power value corresponding to the standard frequency when the SOC of the grid-type energy storage device is adjusted to a normal operating range along with the output power change.

9. An electronic device, characterized in that: include: at least one processor; And a memory connected to the at least one processor; wherein the memory stores instructions that can be executed by the at least one processor, and the instructions are executed by the at least one processor to enable the at least one processor to execute the SOC self-maintenance control method of the power network grid-type energy storage device as described in any one of claims 1-7.

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