A network configuration control method and device applied to a hybrid energy storage system

Abstract

The application discloses a network construction control method and device applied to a hybrid energy storage system, relates to the electrical automation technical field, and mainly aims at improving the capacity utilization rate of super capacitors. The main technical scheme of the application is as follows: real-time power grid operation state parameters, internal state parameters of the hybrid energy storage system and preset control parameters are acquired; the target operation mode into which the hybrid energy storage system should enter is judged based on the real-time power grid operation state parameters, the internal state parameters and the preset control parameters; the target voltage reference value for regulating the voltage of the electrolytic capacitor is generated according to the target operation mode; the target voltage reference value is issued to a partial power bidirectional DC / DC converter, so that the voltage of the electrolytic capacitor is regulated from a current value to the target voltage reference value through the partial power bidirectional DC / DC converter; the voltage of the super capacitor is regulated based on the regulation of the voltage of the electrolytic capacitor to the target voltage reference value, so that the energy storage state of the super capacitor is adapted to the energy demand of the target operation mode.

Description

Technical Field

[0001] This invention relates to the field of electrical automation technology, and in particular to a grid control method and apparatus for hybrid energy storage systems. Background Technology

[0002] With the transformation of the global energy structure, the penetration rate of renewable energy in the power grid continues to increase. However, its volatility and weak inertia characteristics lead to a significant decrease in the frequency and voltage stability of the power grid. Against this backdrop, grid control technology has emerged, aiming to provide the necessary support capabilities for the system by actively establishing and maintaining the voltage amplitude and frequency of the AC power grid.

[0003] The key to achieving efficient grid control lies in the energy storage system's ability to handle rapid, high-power throughput. Supercapacitors, with their extremely high power density, millisecond-level response speed, and excellent cycle life, have become ideal energy storage components for providing virtual inertia and fast frequency response. A typical current approach involves connecting the supercapacitor in parallel to the DC bus via a full-power bidirectional DC / DC converter, and then connecting it to the AC grid via a Static Var Generator (SVG) inverter.

[0004] However, under this architecture, the charging and discharging of supercapacitors is entirely constrained by the voltage regulation requirements of the DC bus and the real-time power commands of the SVG, resulting in a passive response. Its terminal voltage is forcibly constrained within a narrow fluctuation range allowed by the rated voltage of the DC bus, making it impossible to flexibly adjust the operating range according to the dynamic needs of the system. This means that even if the supercapacitor has sufficient physical energy storage, under emergency conditions such as high-power disturbances, the terminal voltage is limited to the narrow fluctuation range allowed by the bus, resulting in a lack of sufficient discharge voltage margin. Consequently, the effective energy that can be released is significantly reduced, and the energy utilization rate is significantly decreased, making it difficult to meet the grid control requirements for instantaneous high-power support. Summary of the Invention

[0005] In view of the above problems, the present invention provides a grid control method and device for hybrid energy storage systems, the main purpose of which is to improve the energy utilization rate of supercapacitors.

[0006] To solve the above-mentioned technical problems, the present invention proposes the following solution: In a first aspect, the present invention provides a grid control method for a hybrid energy storage system, the hybrid energy storage system comprising an SVG main controller, a DC bus, and hybrid energy storage branches connected in parallel to both ends of the DC bus; the hybrid energy storage branch comprises an electrolytic capacitor and a supercapacitor connected in series, the electrolytic capacitor being connected in parallel to a partial-power bidirectional DC / DC converter, the output terminal of the partial-power bidirectional DC / DC converter being connected to the DC bus, the method comprising: The SVG master controller is used to acquire real-time grid operation status parameters, internal status parameters of the hybrid energy storage system, and preset control parameters. The SVG main controller uses the real-time grid operating status parameters, the internal status parameters, and the preset control parameters to determine the target operating mode that the hybrid energy storage system should enter. The SVG main controller generates a target voltage reference value for adjusting the voltage of the electrolytic capacitor based on the target operating mode. The target voltage reference value is sent to the partial power bidirectional DC / DC converter by the SVG master controller, so that the voltage of the electrolytic capacitor can be adjusted from the current value to the target voltage reference value by the partial power bidirectional DC / DC converter. The voltage of the supercapacitor is adjusted by regulating the voltage of the electrolytic capacitor to the target voltage reference value, so that the energy storage state of the supercapacitor is adapted to the energy demand of the target operating mode, thereby realizing grid control.

[0007] Secondly, the present invention provides a grid control device for a hybrid energy storage system, the hybrid energy storage system including an SVG main controller, a DC bus, and hybrid energy storage branches connected in parallel to both ends of the DC bus; the hybrid energy storage branch includes an electrolytic capacitor and a supercapacitor connected in series, the electrolytic capacitor being connected in parallel to a partial-power bidirectional DC / DC converter, the output terminal of the partial-power bidirectional DC / DC converter being connected to the DC bus, the device comprising: The parameter acquisition unit is used to acquire real-time grid operation status parameters, internal status parameters of the hybrid energy storage system, and preset control parameters using the SVG main controller. The mode determination unit is used to determine the target operating mode that the hybrid energy storage system should enter by using the real-time power grid operating status parameters, the internal status parameters and the preset control parameters obtained by the parameter acquisition unit based on the SVG main controller; The numerical generation unit is used to generate a target voltage reference value for adjusting the voltage of the electrolytic capacitor by using the SVG main controller according to the target operating mode obtained by the mode judgment unit; A voltage regulation unit is used to send the target voltage reference value generated by the value generation unit to the partial power bidirectional DC / DC converter using the SVG main controller, so as to control the voltage of the electrolytic capacitor to be adjusted from the current value to the target voltage reference value through the partial power bidirectional DC / DC converter; The mode adaptation unit is used to adjust the voltage of the supercapacitor by adjusting the voltage of the electrolytic capacitor to the target voltage reference value based on the voltage regulation unit, so that the energy storage state of the supercapacitor is adapted to the energy demand of the target operating mode, thereby realizing grid control.

[0008] Thirdly, the present invention provides a hybrid energy storage system, the system comprising: The sampling unit is used to collect real-time power grid operating status parameters and the internal status parameters of the hybrid energy storage system. The SVG main controller is used to determine the target operating mode that the hybrid energy storage system should enter based on the real-time grid operating status parameters, the internal status parameters and the preset control parameters, and to generate the target voltage reference value and active / reactive power command of the electrolytic capacitor under the target operating mode. A partial power bidirectional DC / DC converter is used to adjust the voltage of the electrolytic capacitor according to the target voltage reference value, thereby adjusting the voltage of the supercapacitor; The hybrid energy storage branch includes supercapacitors and electrolytic capacitors connected in series, used to release or absorb energy to the DC bus through the supercapacitors; DC bus, used to collect DC power from hybrid energy storage branches; The SVG converter bridge is used to convert electrical energy on the DC bus into AC power and inject it into the grid, or to absorb electrical energy from the grid and feed it back to the DC bus, thereby achieving grid support.

[0009] To achieve the above objectives, according to a fourth aspect of the present invention, a storage medium is provided, the storage medium including a stored program, wherein, when the program is executed, the device where the storage medium is located is controlled to perform the grid control method of the first aspect applied to a hybrid energy storage system.

[0010] To achieve the above objectives, according to a fifth aspect of the present invention, a processor is provided for running a program, wherein the program executes the grid control method of the first aspect applied to a hybrid energy storage system.

[0011] By employing the above technical solution, this invention provides a grid control method and device for hybrid energy storage systems. By connecting an electrolytic capacitor and a supercapacitor in series to form a hybrid energy storage branch, and introducing a partial-power bidirectional DC / DC converter to actively regulate the voltage of the electrolytic capacitor, this invention effectively solves the problem of low energy utilization caused by the supercapacitor's terminal voltage being forcibly constrained within the narrow fluctuation range of the DC bus in existing technologies. Specifically, the SVG main controller determines the target operating mode based on the grid operating status, system internal status, and preset control parameters, and generates a target voltage reference value for the electrolytic capacitor adapted to this target operating mode. After the electrolytic capacitor voltage is adjusted to this target voltage reference value by the partial-power bidirectional DC / DC converter, the supercapacitor's terminal voltage automatically adjusts to the corresponding level due to the series connection, thus eliminating direct dependence on the DC bus voltage. Under this mechanism, the supercapacitor's operating voltage can be indirectly regulated according to the voltage adjustment of the electrolytic capacitor under different operating modes, thus enabling the effective utilization of physical energy storage that was originally unable to be released due to voltage limitations. This significantly improves the energy utilization rate of supercapacitors in grid control, ensuring that they can fully output the required instantaneous power in emergency support scenarios and effectively meet the high-power response requirements.

[0012] The above description is merely an overview of the technical solution of the present invention. In order to better understand the technical means of the present invention and to implement it in accordance with the contents of the specification, and in order to make the above and other objects, features and advantages of the present invention more apparent and understandable, specific embodiments of the present invention are described below. Attached Figure Description

[0013] Various other advantages and benefits will become apparent to those skilled in the art upon reading the following detailed description of preferred embodiments. The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. Furthermore, the same reference numerals denote the same parts throughout the drawings. In the drawings: Figure 1 A grid connection schematic diagram of a hybrid energy storage system provided by an embodiment of the present invention is shown; Figure 2 This invention provides a flowchart of a grid control method for a hybrid energy storage system. Figure 3 This invention provides a flowchart of another grid control method for hybrid energy storage systems. Figure 4 This diagram illustrates a block diagram of a grid control device for a hybrid energy storage system according to an embodiment of the present invention. Figure 5 This invention provides a block diagram of another grid control device for a hybrid energy storage system. Detailed Implementation

[0014] Exemplary embodiments of the present disclosure will now be described in more detail with reference to the accompanying drawings. While exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure may be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art.

[0015] To address the problems of existing technologies that directly connect supercapacitors in parallel to the DC bus and passively respond to bus voltage fluctuations, this solution constructs a hybrid energy storage branch consisting of an electrolytic capacitor and a supercapacitor connected in series. Guided by the target operating mode, a target voltage reference value is actively set for the electrolytic capacitor. This reference value is used to regulate the electrolytic capacitor voltage, thereby indirectly adjusting the supercapacitor's terminal voltage. This ensures that the supercapacitor's energy storage state matches the energy demands of grid control under different operating modes. Thus, without increasing costs, dynamic adaptive management of the supercapacitor's energy storage state is achieved, fully leveraging its high power density and rapid response advantages to effectively support the voltage establishment, inertia simulation, and instantaneous power throughput capabilities required for grid control.

[0016] Specifically, the hybrid energy storage system of this invention includes an SVG converter bridge, a DC bus, a hybrid energy storage branch, a partial power bidirectional DC / DC converter, a sampling unit, and an SVG main controller. The functions of each part are as follows: SVG converter bridge: As the main power interface, it connects the DC bus and the AC grid, and is responsible for bidirectional AC-DC conversion of electrical energy. Under the power command control of the SVG main controller, it realizes reactive power compensation, voltage support and grid control functions, and is the core execution unit for energy interaction between the system and the grid.

[0017] DC bus: As a common DC voltage node within the system, it provides a stable DC-side voltage platform for the SVG converter bridge, and connects the hybrid energy storage branch and part of the power bidirectional DC / DC converter, forming a hub for energy collection and distribution.

[0018] Hybrid energy storage branch: It consists of an electrolytic capacitor and a supercapacitor connected in series and connected to both ends of the DC bus. The electrolytic capacitor plays the role of high-frequency filtering and voltage buffering, while the supercapacitor has high power instantaneous throughput capability. The series connection structure allows the terminal voltage of the supercapacitor to be indirectly controlled by adjusting the voltage of the electrolytic capacitor, thereby eliminating the direct dependence on the DC bus voltage.

[0019] Partial power bidirectional DC / DC converter: The input is connected in parallel across the electrolytic capacitor, and the output is connected to the DC bus; it only needs to process a portion of the power in the hybrid energy storage branch to accurately and quickly regulate the voltage of the electrolytic capacitor in both directions; under the command of the SVG main controller, it performs the operation of regulating the voltage of the electrolytic capacitor to the target voltage reference value.

[0020] Sampling Unit: Collects real-time grid operation status parameters and internal status parameters of the hybrid energy storage system, and transmits the sampled data to the SVG main controller to provide a basis for mode judgment.

[0021] SVG main controller: As the central control unit of the system, it receives real-time grid operation status parameters, internal status parameters of the hybrid energy storage system, and preset control parameters uploaded by the sampling unit; based on this information, it determines the target operating mode that the system should enter, generates the corresponding target voltage reference value and sends it to the partial power bidirectional DC / DC converter and sends power commands to the SVG converter bridge; by coordinating the voltage relationship between the electrolytic capacitor and the supercapacitor, it adapts the energy storage state of the supercapacitor to the energy demand of the target operating mode, and finally achieves efficient and reliable grid control.

[0022] refer to Figure 1 The diagram shows a hybrid energy storage system connected to the grid. It includes a supercapacitor and an electrolytic capacitor connected in series, which together form a hybrid energy storage branch connected to both ends of the DC bus. A partial-power bidirectional DC / DC converter (labeled "DC / DC" in the diagram) is connected in parallel across the electrolytic capacitor to regulate its voltage. The other side of the DC bus is connected to an SVG converter bridge (labeled "DC / AC" in the diagram) to achieve DC to AC energy conversion. The AC output of the SVG converter bridge is connected in sequence to the line impedance (represented by three parallel diagonal lines), the inductor coil (represented by a wavy pattern as the output filter inductor), and the equivalent power source of the power frequency AC grid (represented by "S" in the circle, representing the public grid, i.e., the target object for which the SVG needs to provide reactive power compensation, voltage / frequency support, and grid stability services).

[0023] It should be noted that, Figure 1 This is a schematic diagram of the main circuit topology, primarily showing the electrical connections between power devices and energy storage elements. The sampling unit (used to collect grid and system internal state parameters) and the SVG main controller (used for operating mode determination, generating target voltage reference values, and issuing control commands) belong to the control system category and are typically not shown in this type of main circuit diagram. Their functions are clearly described in the technical solution of this invention and are consistent with... Figure 1 The main circuit shown works in conjunction with the network control.

[0024] Next, combine Figure 2This invention provides a grid control method for hybrid energy storage systems, the specific execution steps of which are as follows: Figure 2 As shown, steps 201-205 are included: 201. Use the SVG master controller to obtain real-time grid operation status parameters, internal status parameters of the hybrid energy storage system, and preset control parameters.

[0025] Among them, the real-time grid operation status parameters include, but are not limited to, grid frequency and absolute value of frequency change rate; the internal status parameters of the hybrid energy storage system include, but are not limited to, DC bus voltage, electrolytic capacitor voltage and supercapacitor voltage; the preset control parameters include, but are not limited to, frequency change rate threshold, disturbance duration threshold, steady state duration threshold, DC bus overvoltage criterion and supercapacitor low voltage threshold.

[0026] Meanwhile, the present invention also includes pre-set system rating and constraint parameters, which may include the upper and lower limits of DC bus voltage, the upper and lower limits of supercapacitor voltage, the upper and lower limits of electrolytic capacitor voltage, the rated power of a partial power bidirectional DC / DC converter, etc., to ensure that subsequent voltage regulation and energy dispatch operations are performed within safe and feasible physical constraints.

[0027] All of the above parameters are synchronously acquired by the sampling unit at a set sampling period (e.g., 100μs to 1ms) and uploaded in real time to the SVG main controller via the internal communication bus as the basic input data for subsequent operation mode judgment and target voltage reference value generation.

[0028] 202. The SVG master controller is used to determine the target operating mode that the hybrid energy storage system should enter based on real-time grid operating status parameters, internal status parameters and preset control parameters.

[0029] In this step, in order to achieve adaptive response of grid control to different grid operating conditions, the voltage distribution strategy of the hybrid energy storage system needs to be matched with the current system state. Therefore, by using real-time grid operating state parameters, internal state parameters and preset control parameters, the target operating mode that the hybrid energy storage system should enter is determined, thereby providing a decision basis for subsequent generation of target voltage reference values ​​and execution of energy dispatch.

[0030] When determining the target operating mode that the hybrid energy storage system should enter based on real-time grid operating status parameters, internal status parameters, and preset control parameters, any of the following methods can be used: One approach is to compare the real-time power grid operating status parameters and internal status parameters with the corresponding thresholds in the preset control parameters, and directly determine the target operating mode based on the comparison results. Another approach is to use the deviations between real-time power grid operating status parameters and internal status parameters and the corresponding benchmark values ​​in the preset control parameters as input variables. The SVG main controller performs fuzzification processing on these variables and defines fuzzy subsets such as "high", "medium", "low", "normal", and "excessively high". Based on this, a fuzzy rule base is pre-established based on expert experience or historical system operating data. This rule base describes the mapping relationship between different combinations of input variables and the target operating mode. The SVG main controller performs inference through its built-in fuzzy inference engine, and after defuzzification processing, outputs a clear target operating mode.

[0031] The target operating modes include, but are not limited to, steady-state micro-fluctuation operating mode, lifespan extension optimization mode, severe disturbance rapid response mode, energy release mode, and low voltage protection mode. Each of the above operating modes can be triggered independently according to the real-time operating conditions of the power grid and system, or other corresponding modes can be triggered successively after the operation of any mode ends, according to the temporal changes of the operating conditions, so as to realize the adaptive sequential switching between multiple modes.

[0032] 203. Use the SVG master controller to generate a target voltage reference value for adjusting the electrolytic capacitor voltage according to the target operating mode.

[0033] 204. The target voltage reference value is sent to the partial power bidirectional DC / DC converter by the SVG master controller, so that the voltage of the electrolytic capacitor can be adjusted from the current value to the target voltage reference value through the partial power bidirectional DC / DC converter.

[0034] 205. Adjust the voltage of the supercapacitor based on the voltage adjustment of the electrolytic capacitor to the target voltage reference value, so that the energy storage state of the supercapacitor is adapted to the energy demand of the target operating mode, so as to realize grid control.

[0035] In steps 203 to 205, after determining the target operating mode that the hybrid energy storage system should enter, the SVG main controller generates a target voltage reference value for adjusting the electrolytic capacitor voltage based on the target operating mode.

[0036] The target voltage reference value is a command signal issued by the SVG main controller to the partial power bidirectional DC / DC converter. It is used to guide the adjustment of the electrolytic capacitor voltage. By reasonably setting the voltage level of the electrolytic capacitor, the terminal voltage of the supercapacitor connected in series with it falls into the energy available range that is compatible with the current target operating mode, thereby ensuring that the supercapacitor has the ability to release power to meet the energy requirements of this mode.

[0037] For example, in the rapid response mode for severe disturbances, the target voltage reference value is set to a lower value to raise the terminal voltage of the supercapacitor, reserving a larger discharge voltage margin for it, and effectively coping with the instantaneous high power support requirements under large grid disturbances.

[0038] Subsequently, the SVG master controller sends the target voltage reference value to the partial power bidirectional DC / DC converter via a communication interface (such as CAN, SPI, or analog signals). This converter only needs to process a portion of the power flowing through the electrolytic capacitor. Since its function focuses on regulating the voltage distribution in the series circuit, rather than undertaking the entire energy throughput of the energy storage system, it adjusts the actual voltage of the electrolytic capacitor from its current value to the target voltage reference value.

[0039] Because the electrolytic capacitor and the supercapacitor are connected in series and share the same DC bus, the sum of their terminal voltages always equals the DC bus voltage. Therefore, when the voltage of the electrolytic capacitor is adjusted to the target voltage reference value, the terminal voltage of the supercapacitor will automatically adjust to the corresponding level, and its energy storage state will change synchronously. This process requires no direct control operation on the supercapacitor, allowing it to precisely match the instantaneous power support requirements of the current target operating mode.

[0040] For example, in grid construction scenarios requiring high power output, the higher terminal voltage of the supercapacitor provides sufficient voltage margin, enabling it to discharge rapidly across the entire power range. This effectively supports the SVG converter bridge in actively establishing and maintaining the voltage amplitude and frequency of the AC grid, thereby achieving highly reliable grid control.

[0041] Based on the above Figure 2 As can be seen from the implementation method, the grid control method for hybrid energy storage systems provided by this invention connects electrolytic capacitors and supercapacitors in series to form a hybrid energy storage branch, and introduces a partial-power bidirectional DC / DC converter to actively regulate the voltage of the electrolytic capacitors. This invention effectively solves the problem of low energy utilization caused by the supercapacitor terminal voltage being forcibly constrained within the narrow fluctuation range of the DC bus in the prior art. Specifically, the SVG main controller determines the target operating mode based on the grid operating status, the internal system status, and preset control parameters, and generates a target voltage reference value for the electrolytic capacitor adapted to the target operating mode. After the electrolytic capacitor voltage is adjusted to the target voltage reference value by the partial-power bidirectional DC / DC converter, the terminal voltage of the supercapacitor automatically adjusts to the corresponding level due to the series connection between the two, thus eliminating the direct dependence on the DC bus voltage. Under this mechanism, the operating voltage of the supercapacitor can be indirectly regulated according to the voltage adjustment of the electrolytic capacitor under different operating modes, thus enabling the effective utilization of physical energy storage that was originally unable to be released due to voltage limitations. This significantly improves the energy utilization rate of supercapacitors in grid control, ensuring that they can fully output the required instantaneous power in emergency support scenarios and effectively meet the high-power response requirements.

[0042] Furthermore, as a response to Figure 2Further refinement and extension of the illustrated embodiment, this invention also provides another grid control method applied to hybrid energy storage systems, such as... Figure 3 As shown, the specific steps are as follows: 301. Determine the preset control parameters based on the preset optimization target.

[0043] It should be noted in this embodiment that the frequency change rate threshold, disturbance duration threshold, DC bus overvoltage criterion, and supercapacitor low voltage threshold in the control parameters can all be determined by offline optimization methods before the implementation of the dynamic voltage distribution method of the present invention.

[0044] Specifically, multiple sets of candidate control parameters can be pre-constructed; for each set of candidate control parameters that meet the preset constraints, the minimum supercapacitor capacity required to achieve the preset energy support requirements is calculated, and the total number of supercapacitor units is determined based on the minimum supercapacitor capacity; from all the candidate control parameter sets that meet the constraints, the set that minimizes the total number of supercapacitor units is selected as the preset control parameters.

[0045] Among them, the total number of supercapacitor units With minimization as the optimization objective, the total number of supercapacitor cells is determined by both the number of cells connected in series and the number of cells connected in parallel: (Formula 1) Number of series The maximum operating voltage of the supercapacitor With the rated voltage of the unit Decide: (Formula 2) Parallel number Capacity configured by supercapacitor With single-unit capacity Decide: (Formula 3) Among them, the capacity configuration for supercapacitors The following methods can be used to determine this: For any scenario k in the set of disturbance scenarios, let the initial voltage of the supercapacitor at the start of the disturbance be... (k) (given by the margin reserved in the severe disturbance fast response mode), the minimum voltage allowed for disturbance termination is The constraint that the supporting energy is not depleted is then satisfied as follows: (Formula 4) Taking the most stringent scenario, a unified solution for capacity configuration can be obtained: (Formula 5) In the formula, Ω represents the equivalent capacitance of the supercapacitor; k represents the set of disturbance scenarios; k represents the scenario index (k∈Ω); maxk∈Ω(·) represents taking the most stringent value for all scenarios; Energy requirements for the scenario; Energy margin; (k) is the initial voltage of scenario k, which is calculated by the dynamic voltage allocation and scheduling strategy (i.e., the present invention dynamically adjusts the voltage of the electrolytic capacitor according to the change of the target operating mode, thereby realizing the regulation of the voltage of the supercapacitor). Minimum allowable voltage.

[0046] 302. Use the SVG master controller to obtain real-time grid operation status parameters, internal status parameters of the hybrid energy storage system, and preset control parameters.

[0047] The implementation method of step 302 is the same as that of step 201, and can achieve the same technical effect and solve the same technical problem, so it will not be repeated here.

[0048] 303. Use the SVG main controller to determine the target operating mode that the hybrid energy storage system should enter based on real-time grid operating status parameters, internal status parameters and preset control parameters.

[0049] In this step, the absolute value of the frequency change rate in the real-time power grid operating parameters, the DC bus voltage and supercapacitor voltage in the internal state parameters, and the disturbance duration threshold, steady state duration threshold, frequency change rate threshold, DC bus overvoltage criterion, and supercapacitor undervoltage threshold in the preset control parameters can be obtained.

[0050] The triggering rules for each target's operating mode are as follows: If the absolute value of the frequency change rate is less than the frequency change rate threshold, the target operating mode is determined to be the steady-state micro-fluctuation operating mode. This mode is an operating mode in which the supercapacitor autonomously buffers small power disturbances to maintain the stability of the DC bus when the grid frequency is dynamically stable. If the absolute value of the frequency change rate is less than the frequency change rate threshold and the steady-state duration of the system is greater than the steady-state duration threshold, the target operating mode is determined to be the life extension optimization mode. This mode is an optimized operating mode that delays aging and extends the service life by maintaining the supercapacitor voltage within the life protection voltage range during long-term steady-state operation of the system. If the absolute value of the frequency change rate is greater than the frequency change rate threshold and the duration of the disturbance is greater than the duration of the disturbance threshold, the target operating mode is determined to be the severe disturbance rapid response mode. This mode is an emergency response mode that maximizes the discharge margin of the supercapacitor to provide high power inertia support when a continuous large disturbance occurs in the power grid. If the DC bus voltage is greater than the DC bus overvoltage criterion, the target operating mode is determined to be the post-disturbance energy release mode. This mode is a restorative operating mode used to suppress DC bus overvoltage and safely transfer excess energy of the system. If the supercapacitor voltage is less than or equal to the supercapacitor low voltage threshold, the target operating mode is determined to be the low voltage protection mode. This mode prioritizes ensuring the voltage recovery capability of the supercapacitor and limits the output to avoid deep discharge when the supercapacitor's energy storage margin is too low.

[0051] It should be noted that, since this invention is based on the system's real-time operating condition cyclic execution mode determination, each operating mode can be triggered independently according to the corresponding triggering conditions, or it can be triggered sequentially according to the temporal changes of the operating conditions, for example: The lifespan extension optimization mode needs to be continuously operated based on the steady-state micro-fluctuation operation mode and triggered after the steady-state duration condition is met; the energy release mode is mostly triggered after the severe disturbance rapid response mode ends, due to the overvoltage of the bus caused by the grid energy reinjection; the low voltage protection mode can be switched on immediately when the triggering condition is met during or after the operation of the other four modes.

[0052] 304. The SVG master controller generates a target voltage reference value for adjusting the electrolytic capacitor voltage based on the target operating mode.

[0053] When the target operating mode is a steady-state micro-fluctuation mode, the target voltage reference value is set to remain unchanged from its current value, wherein the target voltage reference value does not exceed a preset voltage limit.

[0054] When the target operating mode is the rapid response mode for severe disturbances, the target voltage reference value is set to the preset low voltage value. This is to increase the supercapacitor voltage to close to the upper limit of the supercapacitor voltage in order to reserve the maximum discharge margin and ensure that the supercapacitor participates in inertia support in the optimal voltage range.

[0055] When the target operating mode is energy release mode, the target voltage reference value is set to a preset high voltage value. This is because if the DC bus voltage shows a backflow trend, the SVG main controller can increase the electrolytic capacitor voltage to the preset high voltage value to reduce the supercapacitor voltage. It also controls the DC / DC converter to transfer excess energy to the electrolytic capacitor or via the inverter to the AC side load for absorption, thereby suppressing bus voltage surges.

[0056] When the target operating mode is the life extension optimization mode, the target voltage reference value can be set within the first voltage range (which can be periodically fine-tuned) so that the supercapacitor voltage is within the life protection voltage range, thereby reducing long-term high-voltage stress.

[0057] When the target operating mode is low voltage protection mode, the target voltage reference value is set within the preset recovery range.

[0058] It should be noted that the specific value of the above-mentioned target voltage reference value can be determined comprehensively based on the system rated parameters, current operating conditions and control objectives. This invention does not limit this, but only requires that it meet the preset voltage boundary constraint conditions.

[0059] 305. The target voltage reference value is sent to the partial power bidirectional DC / DC converter using the SVG master controller, so that the voltage of the electrolytic capacitor can be adjusted from the current value to the target voltage reference value through the partial power bidirectional DC / DC converter.

[0060] 306. Adjust the voltage of the supercapacitor based on the voltage adjustment of the electrolytic capacitor to the target voltage reference value, so that the energy storage state of the supercapacitor is adapted to the energy demand of the target operating mode, so as to realize grid control.

[0061] In step 304, to ensure that the voltage regulation process is within a controllable range, after the SVG main controller sends the target voltage reference value to the partial power bidirectional DC / DC converter, the converter can gradually adjust the voltage of the electrolytic capacitor according to the preset voltage change slope limit (i.e., voltage limiting rate) so that it transitions from the current value to the target voltage reference value.

[0062] During this adjustment process, the DC bus voltage, supercapacitor voltage, and electrolytic capacitor voltage can be continuously monitored to ensure that all three remain within the safety boundaries defined by their respective preset upper and lower voltage limits.

[0063] It should be noted that the safety boundaries defined by the preset upper and lower limits of the DC bus voltage, supercapacitor voltage, and electrolytic capacitor voltage can be determined by comprehensively considering factors such as the system's stable operation requirements (e.g., the modulation margin required by the SVG converter bridge to avoid overvoltage or undervoltage instability), energy availability requirements (e.g., ensuring that the supercapacitor has effective discharge capability at critical moments), and relevant industry standards or equipment manufacturer technical specifications.

[0064] The main task of the partial power DC / DC converter in this invention is to change the voltage of the electrolytic capacitor with limited power when entering the corresponding target operating mode. Thus in Internally achieve target voltage distribution and maintain DC bus voltage Do not cross the boundary.

[0065] In the most demanding scenario, the voltage of the electrolytic capacitor needs to be reduced from... Adjust to The completion time is The energy change of the electrolytic capacitor is then: （公式六） In the formula: This represents the change in energy of the electrolytic capacitor. This is the equivalent capacitance of an electrolytic capacitor; , These are the electrolytic capacitor voltages before and after voltage regulation, respectively.

[0066] Ignoring minor losses, the average power that a DC / DC converter needs to handle is: （公式七） In the formula: The average processing power of the DC / DC converter during voltage regulation; This represents the change in energy of the electrolytic capacitor. The time required to complete this voltage scheduling.

[0067] Considering efficiency With safety margin Its rated capacity is recommended to meet the following requirements: （公式八） In the formula: DC / DC rated capacity; This is the safety margin factor, which is generally taken to be greater than 1; The energy amplitude to be processed; For converter efficiency; This is the scheduling completion time.

[0068] To ensure the converter operates within its rated range, the target voltage reference value is... Introduce a preset slope limit: （公式九） In the formula: This represents the rate of change of voltage in the electrolytic capacitor. DC / DC rated capacity; Electrolytic capacitor; This is the voltage of the electrolytic capacitor.

[0069] Subsequently, the voltage of the supercapacitor can be adjusted based on the voltage of the electrolytic capacitor to the target voltage reference value, so that the energy storage state of the supercapacitor can be adapted to the energy demand of the target operating mode, thereby realizing grid control.

[0070] Furthermore, after completing the grid-connection control actions, the SVG master controller can further acquire updated internal state parameters of the hybrid energy storage system, including updated voltage values ​​of the supercapacitors, electrolytic capacitors, and DC bus. Based on these real-time updated voltage data, the current available energy level of the supercapacitors is assessed, and key parameters in the control strategy are dynamically adjusted accordingly. These include preset voltage regulation slope limits for the partial-power bidirectional DC / DC converter, preset power limits for the SVG converter bridge, and threshold hysteresis widths for target operating mode switching, thereby achieving adaptive matching between control parameters and the actual energy storage state of the system.

[0071] The reason for introducing this adaptive adjustment mechanism after the network control is completed is that after the hybrid energy storage system has experienced power throughput (such as large disturbance support or energy release), its internal energy storage state has changed significantly. If the initial or fixed control parameters are still used, it may lead to subsequent adjustments being too aggressive (such as excessive slope causing overshoot) or too conservative (such as excessively strict power limiting weakening response capability). In some cases, the operating mode may even switch frequently near the boundary due to unreasonable threshold hysteresis settings.

[0072] By assessing the available energy of the supercapacitor in real time based on the updated voltage state, and dynamically optimizing the slope limit, power limit, and hysteresis width accordingly, the control system can always be aligned with the current physical state, ensuring safety margins while maximizing the utilization of remaining energy storage resources. This enhances the system's continuous support capability and long-term operational reliability under continuous disturbance conditions.

[0073] Finally, it should be noted that the following constraints must be considered in all embodiments of the present invention: Partial power converter capacity constraints (Formula 10) In the formula: The converter output power at time t; This refers to the rated capacity of the converter.

[0074] 4) Threshold parameter value constraints (Formula Eleven) in, For the frequency change rate threshold, For the duration threshold of the disturbance, The threshold for steady-state duration. , The upper and lower limits of the allowable voltage of the DC bus. DC bus over-criteria This refers to the low-voltage threshold of the supercapacitor. , These are the upper and lower limits of the allowable voltage for supercapacitors; , These are the high and low voltage reference values ​​for the electrolytic capacitor (i.e., preset high voltage and preset low voltage values). Furthermore, as a response to the above Figure 2 In addition to the implementation of the method shown, this embodiment of the invention also provides a grid-connected control device for a hybrid energy storage system, used for the above-described method. Figure 2 The method shown is implemented accordingly. This device embodiment corresponds to the foregoing method embodiment. For ease of reading, this device embodiment will not repeat the details of the foregoing method embodiment, but it should be clear that the device in this embodiment can implement all the contents of the foregoing method embodiment. Figure 4 As shown, the device includes: The parameter acquisition unit 401 is used to acquire real-time grid operation status parameters, internal status parameters of the hybrid energy storage system, and preset control parameters using the SVG main controller. The mode determination unit 402 is used to determine the target operating mode that the hybrid energy storage system should enter by using the SVG main controller based on the real-time grid operating status parameters, the internal status parameters and the preset control parameters obtained by the parameter acquisition unit 401. The numerical generation unit 403 is used to generate a target voltage reference value for adjusting the voltage of the electrolytic capacitor by using the SVG main controller according to the target operating mode obtained by the mode judgment unit 402. The voltage regulation unit 404 is used to send the target voltage reference value generated by the value generation unit 403 to the partial power bidirectional DC / DC converter using the SVG main controller, so as to control the voltage of the electrolytic capacitor to be adjusted from the current value to the target voltage reference value through the partial power bidirectional DC / DC converter; The mode adaptation unit 405 is used to adjust the voltage of the supercapacitor based on the voltage adjustment unit 404 adjusting the voltage of the electrolytic capacitor to the target voltage reference value, so that the energy storage state of the supercapacitor is adapted to the energy demand of the target operating mode, so as to realize grid control.

[0075] Furthermore, as a response to the above Figure 3 In addition to the implementation of the method shown, this embodiment of the invention also provides another grid control device for hybrid energy storage systems, used for the above-mentioned... Figure 3 The method shown is implemented accordingly. This device embodiment corresponds to the foregoing method embodiment. For ease of reading, this device embodiment will not repeat the details of the foregoing method embodiment, but it should be clear that the device in this embodiment can implement all the contents of the foregoing method embodiment. Figure 5 As shown, the device includes: The parameter acquisition unit 401 is used to acquire real-time grid operation status parameters, internal status parameters of the hybrid energy storage system, and preset control parameters using the SVG main controller. The mode determination unit 402 is used to determine the target operating mode that the hybrid energy storage system should enter by using the SVG main controller based on the real-time grid operating status parameters, the internal status parameters and the preset control parameters obtained by the parameter acquisition unit 401. The numerical generation unit 403 is used to generate a target voltage reference value for adjusting the voltage of the electrolytic capacitor by using the SVG main controller according to the target operating mode obtained by the mode judgment unit 402. The voltage regulation unit 404 is used to send the target voltage reference value generated by the value generation unit 403 to the partial power bidirectional DC / DC converter using the SVG main controller, so as to control the voltage of the electrolytic capacitor to be adjusted from the current value to the target voltage reference value through the partial power bidirectional DC / DC converter; The mode adaptation unit 405 is used to adjust the voltage of the supercapacitor based on the voltage adjustment unit 404 adjusting the voltage of the electrolytic capacitor to the target voltage reference value, so that the energy storage state of the supercapacitor is adapted to the energy demand of the target operating mode, so as to realize grid control.

[0076] In one optional implementation, the pattern determination unit 402 is specifically used for: The absolute value of the frequency change rate in the real-time power grid operating parameters, the DC bus voltage and supercapacitor voltage in the internal state parameters, and the disturbance duration threshold, steady state duration threshold, frequency change rate threshold, DC bus overvoltage criterion, and supercapacitor undervoltage threshold in the preset control parameters are obtained. The target operating mode that the hybrid energy storage system should enter is determined based on the absolute value of the frequency change rate, the frequency change rate threshold, the DC bus voltage, the DC bus overvoltage criterion, the supercapacitor voltage, the supercapacitor low voltage threshold, the disturbance duration threshold, and the steady-state duration threshold.

[0077] In one optional implementation, when the mode determination unit 402 determines the target operating mode that the hybrid energy storage system should enter based on the absolute value of the frequency change rate, the frequency change rate threshold, the DC bus voltage, the DC bus overvoltage criterion, the supercapacitor voltage, the supercapacitor low voltage threshold, the disturbance duration threshold, and the steady-state duration threshold, it is specifically used for: If the absolute value of the frequency change rate is less than the frequency change rate threshold, then the target operating mode is determined to be a steady-state micro-fluctuation operating mode. If the absolute value of the frequency change rate is less than the frequency change rate threshold and the steady-state duration is greater than the steady-state duration threshold, then the target operating mode is determined to be the lifespan extension optimization mode. If the absolute value of the frequency change rate is greater than the frequency change rate threshold, and the duration of the disturbance is greater than the duration of the disturbance threshold, then the target operating mode is determined to be the severe disturbance rapid response mode. If the DC bus voltage is greater than the DC bus overvoltage criterion, then the target operating mode is determined to be the energy release mode; If the voltage of the supercapacitor is less than or equal to the low voltage threshold of the supercapacitor, then the target operating mode is determined to be the low voltage protection mode.

[0078] In one optional implementation, the numerical generation unit 403 is specifically used for: When the target operating mode is a steady-state micro-fluctuation mode, the target voltage reference value is set to remain unchanged at its current value, wherein the target voltage reference value does not exceed a preset voltage limit. When the target operating mode is the severe disturbance rapid response mode, the target voltage reference value is set to a preset low voltage value; When the target operating mode is energy release mode, the target voltage reference value is set to a preset high voltage value; When the target operating mode is the life extension optimization mode, the target voltage reference value is set within the first voltage range so that the supercapacitor voltage is within the life protection voltage range. When the target operating mode is low voltage protection mode, the target voltage reference value is set within the preset recovery range.

[0079] In one optional implementation, the voltage regulation unit 404 is specifically used for: The target voltage reference value is sent to the partial power bidirectional DC / DC converter by the SVG master controller, so that the voltage of the electrolytic capacitor is adjusted from the current value to the target voltage reference value by the partial power bidirectional DC / DC converter according to a preset slope limit.

[0080] In an optional implementation, after the mode adaptation unit 405 adjusts the voltage of the supercapacitor based on the voltage of the electrolytic capacitor to the target voltage reference value, so that the energy storage state of the supercapacitor adapts to the energy demand of the target operating mode to achieve grid control, the device further includes a parameter update unit 406, which is specifically used for: The updated internal state parameters of the hybrid energy storage system are obtained using the SVG main controller. These updated internal state parameters include the updated voltage values ​​of the supercapacitor, the updated voltage values ​​of the electrolytic capacitor, and the updated voltage values ​​of the DC bus. The available energy of the supercapacitor is evaluated based on the updated voltage values ​​of the supercapacitor, the electrolytic capacitor, and the DC bus. Based on the available energy conditions, adjust the preset slope limit, preset power limit, and hysteresis width of the threshold used for target operating mode switching.

[0081] In an optional embodiment, before the parameter acquisition unit 401 acquires real-time grid operating status parameters, the internal status parameters of the hybrid energy storage system, and preset control parameters using the SVG main controller, the device further includes a threshold optimization unit 407, which is specifically used for: Acquire multiple pre-constructed candidate control parameters, each of which includes a frequency change rate threshold, a disturbance duration threshold, a DC bus overvoltage criterion, and a supercapacitor low voltage threshold. For each set of candidate control parameters that meet the preset constraints, calculate the minimum supercapacitor capacity required to achieve the preset energy support requirements, and determine the total number of corresponding supercapacitor units based on the minimum supercapacitor capacity. From all candidate control parameter groups that meet the constraints, select the group that minimizes the total number of supercapacitor units as the preset control parameters.

[0082] Furthermore, embodiments of the present invention also provide a storage medium for storing a computer program, wherein the computer program, when running, controls the device where the storage medium is located to execute the above-described... Figure 2-3 The grid control method for hybrid energy storage systems described herein.

[0083] Furthermore, embodiments of the present invention also provide a processor for running a program, wherein the program executes the above-described... Figure 2-3 The grid control method for hybrid energy storage systems described herein.

[0084] In the above embodiments, the descriptions of each embodiment have different focuses. For parts not described in detail in a certain embodiment, please refer to the relevant descriptions in other embodiments.

[0085] It is understood that the relevant features in the above methods and apparatus can be referenced interchangeably. Furthermore, the terms "first," "second," etc., in the above embodiments are used to distinguish between embodiments and do not represent the superiority or inferiority of any particular embodiment.

[0086] Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the specific working processes of the systems, devices, and units described above can be referred to the corresponding processes in the foregoing method embodiments, and will not be repeated here.

[0087] The algorithms and displays provided herein are not inherently related to any particular computer, virtual system, or other device. Various general-purpose systems can also be used in conjunction with the teachings herein. The required structure for constructing such systems is apparent from the above description. Furthermore, this invention is not directed to any particular programming language. It should be understood that the contents of the invention described herein can be implemented using various programming languages, and the above description of specific languages ​​is for the purpose of disclosing the best mode of implementation of the invention.

[0088] In addition, the memory may include non-permanent memory in computer-readable media, such as random access memory (RAM) and / or non-volatile memory, such as read-only memory (ROM) or flash RAM, and the memory includes at least one memory chip.

[0089] Those skilled in the art will understand that embodiments of this application can be provided as methods, systems, or computer program products. Therefore, this application can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, this application can take the form of a computer program product embodied on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0090] This application is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of this application. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart... Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0091] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0092] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0093] In a typical configuration, a computing device includes one or more processors (CPU), input / output interfaces, network interfaces, and memory.

[0094] Memory may include non-persistent memory in computer-readable media, such as random access memory (RAM) and / or non-volatile memory, such as read-only memory (ROM) or flash RAM. Memory is an example of computer-readable media.

[0095] Computer-readable media includes both permanent and non-permanent, removable and non-removable media that can store information using any method or technology. Information can be computer-readable instructions, data structures, modules of programs, or other data. Examples of computer storage media include, but are not limited to, phase-change memory (PRAM), static random access memory (SRAM), dynamic random access memory (DRAM), other types of random access memory (RAM), read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), flash memory or other memory technologies, CD-ROM, digital versatile optical disc (DVD) or other optical storage, magnetic tape, magnetic magnetic disk storage or other magnetic storage devices, or any other non-transferable medium that can be used to store information accessible by a computing device. As defined herein, computer-readable media does not include transient computer-readable media, such as modulated data signals and carrier waves.

[0096] It should also be noted that the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus. Unless otherwise specified, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes that element.

[0097] Those skilled in the art will understand that embodiments of this application can be provided as methods, systems, or computer program products. Therefore, this application can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, this application can take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0098] The above are merely embodiments of this application and are not intended to limit the scope of this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the scope of the claims of this application.

Claims

1. A grid-based control method for hybrid energy storage systems, characterized in that, The hybrid energy storage system includes an SVG main controller, a DC bus, and hybrid energy storage branches connected in parallel to both ends of the DC bus; the hybrid energy storage branch includes an electrolytic capacitor and a supercapacitor connected in series, the electrolytic capacitor is connected in parallel to a partial-power bidirectional DC / DC converter, and the output of the partial-power bidirectional DC / DC converter is connected to the DC bus; the method includes: The SVG master controller is used to acquire real-time grid operation status parameters, internal status parameters of the hybrid energy storage system, and preset control parameters. The SVG main controller uses the real-time grid operation status parameters, the internal status parameters, and the preset control parameters to determine the target operation mode that the hybrid energy storage system should enter. The SVG main controller generates a target voltage reference value for adjusting the voltage of the electrolytic capacitor based on the target operating mode. The target voltage reference value is sent to the partial power bidirectional DC / DC converter by the SVG master controller, so that the voltage of the electrolytic capacitor can be adjusted from the current value to the target voltage reference value by the partial power bidirectional DC / DC converter. The voltage of the supercapacitor is adjusted by regulating the voltage of the electrolytic capacitor to the target voltage reference value, so that the energy storage state of the supercapacitor is adapted to the energy demand of the target operating mode, thereby realizing grid control.

2. The method according to claim 1, characterized in that, The SVG main controller determines the target operating mode that the hybrid energy storage system should enter based on the real-time grid operating status parameters, the internal status parameters, and the preset control parameters, including: The absolute value of the frequency change rate in the real-time power grid operating parameters, the DC bus voltage and supercapacitor voltage in the internal state parameters, and the disturbance duration threshold, steady state duration threshold, frequency change rate threshold, DC bus overvoltage criterion, and supercapacitor undervoltage threshold in the preset control parameters are obtained. The target operating mode that the hybrid energy storage system should enter is determined based on the absolute value of the frequency change rate, the frequency change rate threshold, the DC bus voltage, the DC bus overvoltage criterion, the supercapacitor voltage, the supercapacitor low voltage threshold, the disturbance duration threshold, and the steady-state duration threshold.

3. The method according to claim 2, characterized in that, The target operating mode that the hybrid energy storage system should enter is determined based on the absolute value of the frequency change rate, the frequency change rate threshold, the DC bus voltage, the DC bus overvoltage criterion, the supercapacitor voltage, the supercapacitor low voltage threshold, the disturbance duration threshold, and the steady-state duration threshold, including: If the absolute value of the frequency change rate is less than the frequency change rate threshold, then the target operating mode is determined to be a steady-state micro-fluctuation operating mode. If the absolute value of the frequency change rate is less than the frequency change rate threshold and the steady-state duration is greater than the steady-state duration threshold, then the target operating mode is determined to be the lifespan extension optimization mode. If the absolute value of the frequency change rate is greater than the frequency change rate threshold, and the duration of the disturbance is greater than the duration of the disturbance threshold, then the target operating mode is determined to be the severe disturbance rapid response mode. If the DC bus voltage is greater than the DC bus overvoltage criterion, then the target operating mode is determined to be the energy release mode; If the voltage of the supercapacitor is less than or equal to the low voltage threshold of the supercapacitor, then the target operating mode is determined to be the low voltage protection mode.

4. The method according to any one of claims 1-3, characterized in that, The SVG main controller generates a target voltage reference value for adjusting the electrolytic capacitor voltage according to the target operating mode, including: When the target operating mode is a steady-state micro-fluctuation mode, the target voltage reference value is set to remain unchanged at its current value, wherein the target voltage reference value does not exceed a preset voltage limit. When the target operating mode is the severe disturbance rapid response mode, the target voltage reference value is set to a preset low voltage value; When the target operating mode is energy release mode, the target voltage reference value is set to a preset high voltage value; When the target operating mode is the life extension optimization mode, the target voltage reference value is set within the first voltage range so that the supercapacitor voltage is within the life protection voltage range. When the target operating mode is low voltage protection mode, the target voltage reference value is set within the preset recovery range.

5. The method according to claim 1, characterized in that, The SVG master controller sends the target voltage reference value to the partial-power bidirectional DC / DC converter, so that the partial-power bidirectional DC / DC converter controls the voltage of the electrolytic capacitor to adjust from the current value to the target voltage reference value, including: The target voltage reference value is sent to the partial power bidirectional DC / DC converter by the SVG master controller, so that the voltage of the electrolytic capacitor is adjusted from the current value to the target voltage reference value by the partial power bidirectional DC / DC converter according to a preset slope limit.

6. The method according to claim 1, characterized in that, After adjusting the voltage of the supercapacitor based on the voltage of the electrolytic capacitor to the target voltage reference value, so that the energy storage state of the supercapacitor matches the energy demand of the target operating mode to achieve grid control, the method further includes: The updated internal state parameters of the hybrid energy storage system are obtained using the SVG main controller. These updated internal state parameters include the updated voltage values ​​of the supercapacitor, the updated voltage values ​​of the electrolytic capacitor, and the updated voltage values ​​of the DC bus. The available energy of the supercapacitor is evaluated based on the updated voltage values ​​of the supercapacitor, the electrolytic capacitor, and the DC bus. Based on the available energy conditions, adjust the preset slope limit, preset power limit, and hysteresis width of the threshold used for target operating mode switching.

7. The method according to claim 1, characterized in that, Before using the SVG master controller to obtain real-time grid operating status parameters, the internal status parameters of the hybrid energy storage system, and preset control parameters, the method further includes: Acquire multiple pre-constructed candidate control parameters, each of which includes a frequency change rate threshold, a disturbance duration threshold, a DC bus overvoltage criterion, and a supercapacitor low voltage threshold. For each set of candidate control parameters that meet the preset constraints, calculate the minimum supercapacitor capacity required to achieve the preset energy support requirements, and determine the total number of corresponding supercapacitor units based on the minimum supercapacitor capacity. From all candidate control parameter groups that meet the constraints, select the group that minimizes the total number of supercapacitor units as the preset control parameters.

8. A grid control device for a hybrid energy storage system, characterized in that, The hybrid energy storage system includes an SVG main controller, a DC bus, and hybrid energy storage branches connected in parallel to both ends of the DC bus; the hybrid energy storage branches include an electrolytic capacitor and a supercapacitor connected in series, the electrolytic capacitor is connected in parallel to a partial-power bidirectional DC / DC converter, and the output of the partial-power bidirectional DC / DC converter is connected to the DC bus. The device includes: The parameter acquisition unit is used to acquire real-time grid operation status parameters, internal status parameters of the hybrid energy storage system, and preset control parameters using the SVG main controller. The mode determination unit is used to determine the target operating mode that the hybrid energy storage system should enter by using the real-time power grid operating status parameters, the internal status parameters and the preset control parameters obtained by the parameter acquisition unit based on the SVG main controller; The numerical generation unit is used to generate a target voltage reference value for adjusting the voltage of the electrolytic capacitor by using the SVG main controller according to the target operating mode obtained by the mode judgment unit; A voltage regulation unit is used to send the target voltage reference value generated by the value generation unit to the partial power bidirectional DC / DC converter using the SVG main controller, so as to control the voltage of the electrolytic capacitor to be adjusted from the current value to the target voltage reference value through the partial power bidirectional DC / DC converter; The mode adaptation unit is used to adjust the voltage of the supercapacitor by adjusting the voltage of the electrolytic capacitor to the target voltage reference value based on the voltage regulation unit, so that the energy storage state of the supercapacitor is adapted to the energy demand of the target operating mode, thereby realizing grid control.

9. A hybrid energy storage system, characterized in that, The system includes: The sampling unit is used to collect real-time power grid operating status parameters and the internal status parameters of the hybrid energy storage system. The SVG main controller is used to determine the target operating mode that the hybrid energy storage system should enter based on the real-time grid operating status parameters, the internal status parameters and the preset control parameters, and to generate the target voltage reference value and active / reactive power command of the electrolytic capacitor under the target operating mode. A partial power bidirectional DC / DC converter is used to adjust the voltage of the electrolytic capacitor according to the target voltage reference value, thereby adjusting the voltage of the supercapacitor; The hybrid energy storage branch includes supercapacitors and electrolytic capacitors connected in series, used to release or absorb energy to the DC bus through the supercapacitors; DC bus, used to collect DC power from hybrid energy storage branches; The SVG converter bridge is used to convert electrical energy on the DC bus into AC power and inject it into the grid, or to absorb electrical energy from the grid and feed it back to the DC bus, thereby achieving grid support.

10. A storage medium, characterized in that, The storage medium includes a stored program, wherein, when the program is executed, it controls the device containing the storage medium to perform the grid control method for a hybrid energy storage system as described in any one of claims 1 to 7.

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