SOC self-maintenance control method and system for power network construction type energy storage device

Abstract

The invention discloses an SOC self-maintenance control method and system for power network construction type energy storage devices. The method comprises the following steps: respectively acquiring SOCs of a plurality of network construction type energy storage devices; and when the SOC of any network-building type energy storage device is greater than the upper limit value of the normal operation interval or less than the lower limit value of the normal operation interval, re-assigning an output power value corresponding to the standard frequency of the network-building type energy storage device through an energy storage device converter, and controlling the network-building type energy storage device to enter a self-maintenance state. The frequency value of the energy storage device converter is changed along with the change of the output power value corresponding to the re-assigned standard frequency, so as to drive the output power of other network-forming energy storage devices in the power network to change, and further drive the output power of the network-forming energy storage devices to change; and when the SOC of the networking type energy storage device is adjusted to a normal operation interval along with the change of the output power, the output power value corresponding to the standard frequency is recovered to the initial power value corresponding to the standard frequency.

Description

Technical Field

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

[0002] With the rapid growth of renewable energy generation, the contradiction between the large-scale development of renewable energy and its efficient consumption and utilization has become increasingly prominent. The new power system with new energy as the main body, while benefiting from the advantages of new energy such as sustainability and clean and low carbon, is also challenged by its own uncertainty and low inertia characteristics. The investment and construction of energy storage can effectively solve the high uncertainty and low inertia problems of the power system under the high penetration of new energy, but the traditional energy storage participating in grid dispatching mainly adjusts the power according to the instructions after receiving the dispatching and control instructions. With the gradual implementation of incentive policies for clean energy and green electricity consumption, and with the increase in the construction of regional energy autonomous grids and local grids, it has become a trend to use energy storage as a voltage source to participate in or dominate the frequency and voltage regulation of the grid. The electrochemical energy storage system completes the bidirectional transmission of power through the energy storage converter PCS, while the battery completes the release and storage of energy. When the energy storage is operated as the main power source, in addition to the PCS power margin, the energy margin of the energy storage battery also becomes an important indicator of sustainable power supply of the power grid. Therefore, the maintenance of the state of charge SOC of the energy storage battery is an important task to improve the reliability of power supply. Since the power change of grid-type energy storage is closely related to the grid frequency deviation value, when the energy storage SOC needs to be maintained, the state of charge of the energy storage battery is often adjusted by switching from the voltage source to the power source mode. This energy storage SOC maintenance method weakens the power regulation autonomy of the grid-type energy storage, and the superior control system corresponding to the PCS formulates control strategies based on the safety, stability and economy of the regional energy autonomous power grid or the local power grid. In the strategy formulation, if the influence of the energy storage SOC constraint and the change of the PCS working mode of the grid-type energy storage device converter are always considered, the control strategy branches will increase, and there will be the possibility of repeatedly adjusting the droop coefficient of the grid-type energy storage, thereby increasing the calculation amount and strategy complexity of the power adjustment allocation of the superior dispatching system, and reducing the coherence 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 of an electric power network, which reduces the expansion of the grid frequency fluctuation range and duration caused by the insufficient smoothness of the switching of the control strategy by improving the continuity of the regional energy autonomous power grid or the local power grid control strategy, and ensures the stability of the regional energy autonomous power grid, especially the local power grid including multi-point grid-type energy storage running in parallel.

[0004] In order to solve the above technical problems, a first aspect of an embodiment of the present invention provides a self-maintenance control method for SOC of a grid-type energy storage device in a power network, wherein the power network comprises a plurality of grid-type energy storage devices operating in parallel at multiple points, wherein the plurality of grid-type energy storage devices are respectively connected to the power network through energy storage device converters, and the control method comprises 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-forming energy storage devices in the power network to change, thereby driving the output power of the grid-forming 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 re-assigned standard frequency corresponding output power value of the 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 grid-type energy storage device SOC self-maintenance control method also 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 state of the current grid-type energy storage device is consistent with the charge and discharge state 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 grid-type energy storage device SOC self-maintenance control method also 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 grid-type energy storage device SOC self-maintenance control method also 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 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 corresponding power value of 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 standard frequency corresponding output power value of the energy storage device converter is restored to the initial corresponding power value of 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 power network grid-type energy storage device SOC self-maintenance control system, 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 through energy storage device converters, respectively, and the control system includes:

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

[0029] A power assignment module, 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, so as to control 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 standard frequency corresponding output power value, driving the output power of other grid-forming energy storage devices in the power network to change, and further driving the output power of the grid-forming 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 corresponding power value of 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 executable 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 grid-type energy storage device in a power network.

[0034] The above technical solution of the embodiment of the present invention has 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, which does not rely on the communication network and does not require superior dispatching instructions, thereby 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 take into account the SOC maintenance of the grid-type energy storage device at all times, and does not need to make repeated adjustments for the SOC maintenance of the grid-type energy storage device, which 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 jointly undertaken by all grid-connected power electronic equipment, which reduces the range of frequency fluctuations and ensures the smooth transition of the regional energy autonomous power grid or local power grid state. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 It is a flow chart of a SOC self-maintenance control method of a power network grid-type energy storage device provided by 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 It is a schematic diagram of the SOC self-maintenance process of the grid-type energy storage device provided by an embodiment of the present invention;

[0041] Figure 4 It is a block diagram of the SOC self-maintenance control system module of the power network grid-type energy storage device provided in 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] In order to make the purpose, technical scheme and advantages of the present invention clearer, the present invention is 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 only exemplary and are not intended to limit the scope of the present invention. In addition, in the following description, the description of well-known structures and technologies is omitted to avoid unnecessary confusion of the concept of the present invention.

[0045] The grid-type energy storage devices with multiple points of layout together form the frequency and voltage active support system of the regional energy autonomous power grid or the local power grid. When the grid-type energy storage device is working normally, the energy storage device converter PCS adopts the voltage source control mode, and the droop coefficient determines the power change provided by each grid-type energy storage when the frequency changes, so that the system can reach a new steady state. The power value corresponding to the standard frequency determines the output of the grid-type energy storage when the grid is in a frequency-free state, which can be adjusted by the local or superior dispatching system according to the real-time and future operating conditions.

[0046] Please refer to Figure 1A first aspect of an embodiment of the present invention provides a self-maintenance control method for 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, and the plurality of grid-type energy storage devices are connected to the power network through energy storage device converters PCS, respectively, and the control method includes the following steps:

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

[0048] The above-mentioned power network includes: regional energy autonomous power grid or local power grid. At present, there are multiple power supply points in regional energy autonomous power grid or local power grid. The network architecture adopts multi-voltage source multi-point distribution. The voltage source contains multiple energy storage converters using grid-type energy storage control technology. The network operation mode is a power grid with multiple voltage sources operating in parallel.

[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 to control the grid-type energy storage device to enter a self-maintenance state.

[0050] In the self-maintenance state, the frequency value of the energy storage device inverter 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 then driving the output power changes of the grid-forming energy storage device.

[0051] When the SOC of a grid-type energy storage device in a regional energy autonomous power grid or a local power grid reaches the upper or lower limit of the normal operating range, the SOC self-maintenance function of the energy storage device is activated; at this time, the energy storage device converter PCS reassigns the initial corresponding power value P0 of the standard frequency according to the optimal charge and discharge ratio corresponding to the battery capacity and its own characteristics of the energy storage device. When the new value obtained by PCS after the reassignment of P0 causes the current point frequency to fluctuate, the output of the remaining grid-type power sources in the grid changes due to the frequency fluctuation, and then the output of the energy storage device converter PCS that performs self-maintenance of the SOC of the energy storage device changes in the direction of improving the state of charge of the energy storage battery, and the frequency and power of the regional energy autonomous power grid or the local power grid also reaches a new stable state. As the charging (discharging) time passes, the SOC of the energy storage device is gradually restored to the median of the normal value range, and the original initial corresponding power value P0 of 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 scheme, the power network architecture adopts multi-voltage source multi-point distribution, the voltage source includes multiple energy storage inverters adopting grid-type energy storage control technology, the network operation mode is multi-voltage source parallel operation mode, and 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 frequency-free state. 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 through the energy storage device inverter PCS according to the optimal charge and discharge rate corresponding to the energy storage battery's own capacity and its own characteristics, and 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 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 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] 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 of the normal operating range or less than the lower limit of the normal operating range, the other grid-type energy storage devices are controlled to enter the self-maintenance state. When a grid-type energy storage device is in the SOC maintenance period, and the SOC of other grid-type energy storage devices also reaches the upper or lower limit of the normal operating range, the other grid-type energy storage devices are controlled to start the SOC self-maintenance function of the energy storage devices.

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

[0061] If the charge and discharge state of the current grid-type energy storage device is consistent with the charge and discharge state 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 other grid-type energy storage devices are consistent with their respective SOC adjustment directions.

[0062] At this time, if other grid-type energy storages that have reached the limit of the normal operating range are in the same maintenance direction as the previous grid-type energy storage (the same is charging or discharging), it is possible to 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 that requires 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 superior 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 SOC self-maintenance control method of the grid-type energy storage device of the power network 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 corresponding power value of 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 corresponding power value of the standard frequency.

[0066] During the SOC maintenance of the grid-type energy storage device, when the regional energy autonomous power grid or the local power grid enters an emergency processing state, the energy storage device converter PCS that performs the SOC self-maintenance of the grid-type energy storage device senses a sudden change in voltage or frequency and automatically exits the SOC maintenance and restores the original initial power value P0. If the grid voltage and frequency return to normal after 15s, the SOC self-maintenance will continue; if the grid is still in the normal operating range, the working mode will be controlled according to the command of the superior dispatching system. At this time, there is a risk of PCS exiting work due to operating conditions or too low SOC. When the grid parameters return to the normal operating range, a new round of SOC self-maintenance function of the grid-type energy storage device is started after the SOC of the grid-type 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 self-maintenance of the SOC 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 grid 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, 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 power grid or the local power 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 according to 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 other grid-type power sources in the grid (such as grid-type energy storage device 2 and grid-type energy storage device 3) produce output changes due to frequency fluctuations, 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 PCS output power of the energy storage device converter and the battery SOC maintenance optimal charge and discharge power ratio are not calculated between 70% and 120% after the grid frequency stabilizes, the P 0-1 Reassign value.

[0076] Accordingly, a second aspect of an embodiment of the present invention provides a power network grid-type energy storage device SOC self-maintenance control system, 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 connected to the power network through energy storage device converters, respectively, and the control system includes:

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

[0078] A power assignment module 2 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 a 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, so as to control the grid-type energy storage device to enter a 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 of other grid-forming energy storage devices in the power network to change, and then driving the output power of the grid-forming energy storage device to change;

[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 executable 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 grid-type energy storage device in a power network.

[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 respectively connected to the electric power network through energy storage device converters, and the control method includes the following steps: respectively obtaining the SOC of the plurality of grid-type energy storage devices; 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, reassigning the standard frequency corresponding output power value of the grid-type energy storage device through the energy storage device converter, and 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 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 further 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 scheme has the following effects:

[0084] 1. The SOC maintenance function of the energy storage device is implemented locally by the energy storage device converter PCS, which does not rely on the communication network and does not require superior dispatch instructions, thereby 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 take into account the SOC maintenance of the grid-type energy storage device at all times, and does not need to make repeated adjustments for the SOC maintenance of the grid-type energy storage device, which 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 jointly undertaken by all grid-connected power electronic equipment, which reduces the range of frequency fluctuations and ensures the smooth transition of the regional energy autonomous power grid or local power grid state.

[0087] Those skilled in the art will appreciate that the embodiments of the present application may be provided as methods, systems, or computer program products. Therefore, the present application may 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 may adopt the form of a computer program product implemented in one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) that include 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 generate a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. 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 capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture including an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A 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 operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified 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 rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, ordinary technicians in the relevant 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 within 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 energy storage device, characterized in that: The power network includes a plurality of grid-forming energy storage devices operating in parallel at multiple points, wherein the plurality of grid-forming energy storage devices are connected to the power network through energy storage device converters respectively, and 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-forming energy storage devices in the power network to change, thereby driving the output power of the grid-forming 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.

2. The SOC self-maintenance control method of the power network grid-type energy storage device according to claim 1 is characterized in that: 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 re-assigned standard frequency corresponding output power value of the 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.

3. The SOC self-maintenance control method of the power network grid-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.

4. The SOC self-maintenance control method of the power network energy storage device according to claim 3 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 state of the current grid-type energy storage device is consistent with the charge and discharge state 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.

5. The SOC self-maintenance control method of the power network grid-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.

6. The SOC self-maintenance control method of the power network grid-type energy storage device according to claim 1 is 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 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 corresponding power value of 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 standard frequency corresponding output power value of the energy storage device converter is restored to the initial corresponding power value of the standard frequency.

7. The SOC self-maintenance control method of the power network grid-type energy storage device according to claim 6 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.

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

9. A power network grid-type energy storage device SOC self-maintenance control system, characterized in that: The power network includes a plurality of grid-forming energy storage devices operating in parallel at multiple points, wherein the plurality of grid-forming energy storage devices are connected to the power network through energy storage device converters respectively, and the control system includes: A state acquisition module, which is used to respectively acquire the SOC of a plurality of grid-type energy storage devices; A power assignment module, 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, so as 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-forming energy storage devices in the power network to change, thereby driving the output power of the grid-forming 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 corresponding power value of 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.

10. 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 so that the at least one processor executes the SOC self-maintenance control method of the power network grid-type energy storage device as described in any one of claims 1-8.

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