All-dc collection network type energy storage isolated network starting control method and system

Abstract

This application relates to the field of power grid control technology, specifically disclosing a startup control method and system for islanded energy storage networks with all-DC converged grids. It aims to solve the problems of single-point failure and low reliability inherent in existing centralized control systems. This method monitors DC bus voltage, frequency fluctuations, and power change rate, and combines fuzzy logic algorithms to fuse multiple parameters to determine if the system is in a dormant state. If dormant, each energy storage unit, through distributed negotiation, calculates a priority score based on its own state information to select a master startup unit. The master startup unit executes an adaptive soft-start algorithm to establish the rated voltage of the DC bus. The startup status of each unit is monitored; if preset conditions are not met, a fault-tolerant reselection mechanism is used to reselect a master unit. If conditions are met, the units are sequentially connected to the bus and switched to the grid construction mode to complete the islanded network construction. This application employs distributed control, avoiding single-point dependence, improving the reliability and adaptability of islanded network startup, and ensuring efficient and stable system startup.

Description

Technical Field

[0001] This application relates to the field of power grid control technology, and in particular to a start-up control method and system for an all-DC converged grid-type energy storage isolated grid. Background Technology

[0002] With the continuous expansion of global renewable energy generation, all-DC convergence systems centered on photovoltaics and energy storage are emerging. These systems integrate renewable energy generation, energy storage, load, and control components using DC connections, achieving centralized collection, distribution, and transmission of power via DC buses. While normally connected to the main grid, these systems must disconnect from the grid and operate independently during grid failures, maintenance, or specific dispatching needs. This islanding capability ensures continuous power supply to critical loads and prevents safety risks or economic losses due to power outages.

[0003] The islanded start-up control of a fully DC-connected grid-connected energy storage system mainly relies on a centralized control scheme. Its core logic is as follows: a central controller is set up to uniformly monitor the operating status of each energy storage unit and the DC bus voltage, among other data. When it is determined that the system needs islanded start-up, the central controller, according to a preset logic sequence, designates a specific energy storage unit and its converter to start first. The converter of this unit pre-charges the DC bus to establish the rated voltage. After the bus voltage stabilizes, the central controller then sequentially sends start-up commands to other energy storage units and new energy generation units, thus ultimately completing the islanded grid construction.

[0004] However, in actual use, this central control setting logic has the following technical problems: First, a single point of failure is fatal. The entire process relies on the central controller and the preset start-up unit. If either of them fails due to a fault, communication interruption, or insufficient charge, the start-up will completely fail. Moreover, the response and reliability are poor. The system covers a wide range of areas, the equipment is scattered and heterogeneous, and long-distance communication delays cause instructions to lag. Equipment adaptation is difficult, which will further reduce the reliability of the start-up.

[0005] Therefore, there is an urgent need for a start-up control method and system for all-DC combined grid-type energy storage systems to solve the above problems.

[0006] Application content

[0007] The purpose of this application is to provide a start-up control method for islanded energy storage networks with all-DC converged grids, including the following steps:

[0008] Monitor whether the grid-type energy storage system is in a dormant state, wherein the grid-type energy storage system includes multiple energy storage units;

[0009] In a dormant state, each energy storage unit in the grid-type energy storage system sends a distributed negotiation command with its own status information to all other multiple energy storage units, and receives its own status information from all other multiple energy storage units. Each energy storage unit calculates a priority score based on all its own status information and sends the priority score to other energy storage units. In this case, the connection between multiple energy storage units and the DC bus is interrupted.

[0010] Each energy storage unit selects the corresponding target energy storage unit as the main start-up unit based on all priority scores, and the remaining energy storage units are designated as slave units.

[0011] The main start-up unit executes an adaptive soft-start algorithm to pre-charge the DC bus connected to the grid-type energy storage system so that the DC bus voltage reaches the rated value.

[0012] Each of the slave units monitors whether the startup status of the main startup unit meets the preset conditions according to preset requirements;

[0013] If the preset conditions are not met, each slave unit sends a fault-tolerant reselection instruction to all other slave units;

[0014] Each slave unit reselects a target master boot unit according to the fault-tolerant reselection instruction;

[0015] If the preset conditions are met, all energy storage units except the main start-up unit will act as slave units, re-establish electrical connections with the DC bus based on their own converters, and form voltage regulation to complete the construction of the islanded grid.

[0016] Furthermore, the step of monitoring whether the grid-type energy storage system is in a dormant state includes:

[0017] Monitor the DC bus voltage of the grid-type energy storage system, collect the raw voltage data of the DC bus at the connection point between each energy storage unit and the DC bus, and simultaneously collect the frequency fluctuation data of the grid-type energy storage system and the output power change rate of each energy storage unit.

[0018] Obtain the preset voltage threshold, frequency stability threshold, and power change rate threshold for the grid-type energy storage system;

[0019] The original voltage data is processed to obtain the filtered voltage value. At the same time, a sliding window variance analysis is performed on the frequency fluctuation data to obtain the frequency stability index. The output power change rate is trend-fitted to obtain the power attenuation slope.

[0020] The filtered voltage value is compared with the voltage threshold, the frequency stability index is compared with the frequency stability threshold, and the power attenuation slope is compared with the power change rate threshold.

[0021] Based on the fuzzy logic algorithm, the voltage comparison results, frequency stability comparison results and power attenuation comparison results are fused and calculated to obtain the system silence confidence.

[0022] If the system's dormancy confidence level exceeds a preset confidence threshold and the duration exceeds a first preset time, then the grid-type energy storage system is determined to have entered a dormant state.

[0023] Furthermore, the step of calculating the priority score for each energy storage unit based on all its own state information includes:

[0024] Extract the state of charge, rated capacity, and electrical distance parameters from the system core bus from the self-state information;

[0025] Identify the current operating modes of the grid-type energy storage system, including the rapid recovery mode, the stable operation mode, and the economical operation mode;

[0026] Based on the identified operational mode category, modal adaptation and reconstruction are performed on the self-state information, including:

[0027] In the fast recovery mode, the state of charge value is reconstructed to the maximum supportable power value;

[0028] Under stable operating conditions, the rated capacity value is reconstructed into a capacity stability coefficient;

[0029] Under the economic operation mode, the electrical distance parameter is reconstructed into a transmission efficiency factor;

[0030] Based on the reconstructed self-state information, a multimodal competitive scoring matrix is ​​established, and the modal fit score of each energy storage unit under different operating modes is calculated.

[0031] Based on the modal fit score of each energy storage unit in the current operating mode, and combined with its relative ranking in other operating modes, the modal competitive advantage value is calculated.

[0032] Based on the modal competitive advantage value, the final priority score is generated;

[0033] Each energy storage unit broadcasts the priority score as part of the distributed negotiation instruction to all other energy storage units.

[0034] Furthermore, the main starting unit executes an adaptive soft-start algorithm to pre-charge the DC bus connected to it so that the DC bus voltage reaches the rated voltage. This step includes:

[0035] Each energy storage unit compares all priority scores and determines the energy storage unit with the highest priority score as the target energy storage unit.

[0036] The target energy storage unit is set as the master start-up unit, and the remaining energy storage units are set as slave units.

[0037] The main starting unit acquires the control parameters of its converter, including the rated voltage, time constant, and maximum allowable current.

[0038] Based on the control parameters, the main start-up unit executes an adaptive soft-start algorithm to bring the DC bus into a voltage build-up state:

[0039] The main starting unit controls the voltage output of its converter to the DC bus to start from zero and gradually approach the rated voltage in an exponential growth pattern.

[0040] During the voltage rise process, the main start-up unit samples the DC bus charging current in real time and limits the current to below the maximum allowable current so that the DC bus voltage reaches the rated voltage.

[0041] The master startup unit periodically sends heartbeat signals to each slave unit.

[0042] Furthermore, the step of each slave unit monitoring whether the startup status of the main startup unit meets preset conditions according to preset requirements includes:

[0043] Each slave unit continuously monitors the DC bus voltage establishment status and determines whether the DC bus voltage reaches the preset stable range of the rated voltage within a second preset time.

[0044] Each slave unit continuously monitors the heartbeat signal periodically broadcast by the master startup unit and determines whether the slave unit has received a valid signal within a preset number of consecutive times;

[0045] If the DC bus voltage fails to reach the preset stable range within the second preset time, or if the heartbeat signal is lost for a preset number of consecutive times, it is determined that the preset condition is not met.

[0046] If the DC bus voltage reaches a stable range within a second preset time and a valid heartbeat signal is received within a preset number of times, then the preset conditions are deemed met.

[0047] Furthermore, if the preset conditions are not met, each slave unit sends a fault-tolerant reselection instruction to all other slave units. The step of each slave unit reselecting the target master boot unit according to the fault-tolerant reselection instruction includes:

[0048] If the preset conditions are not met, each slave unit analyzes the triggering factors of the main start-up unit failure, including the characteristics of DC bus voltage build-up failure, heartbeat signal loss mode, and failure occurrence time characteristics.

[0049] A re-election mode recognition mechanism is established based on the aforementioned triggering factors. A re-election strategy is determined based on the characteristics of pressure failure and the heartbeat signal loss mode. The re-election strategy includes a fast recovery mode and a smooth switching mode.

[0050] In fast recovery mode, each slave unit calls preset dynamic capability profile data, which is constructed based on the historical startup success rate, voltage support response time and current environmental adaptability of each unit.

[0051] Based on the dynamic capability profile data, an emergency situation assessment algorithm is used to directly generate the emergency priority score of the candidate unit, thereby skipping the conventional priority score calculation process.

[0052] In smooth switching mode, each slave unit constructs a cooperative operation matching matrix based on the rated capacity coordination of each unit and the similarity of converter control characteristics, and calculates the cooperative operation efficiency value between units.

[0053] Based on the identified re-election mode, the corresponding evaluation data is selected. In the rapid recovery mode, the emergency priority score is used, and in the smooth switching mode, the collaborative operation efficiency value is used.

[0054] Based on the selected evaluation data, a rapid election process is executed to determine the slave unit with the highest emergency priority score or collaborative operation efficiency score in the corresponding mode as the new master startup unit.

[0055] Furthermore, if preset conditions are met, all energy storage units except the main start-up unit, acting as slave units, re-establish electrical connections with the DC bus based on their own converters and form voltage regulation to complete the construction of the islanded grid. The steps include:

[0056] If the preset conditions are met, each slave unit obtains a DC bus voltage stability signal and determines whether the DC bus voltage is maintained within the preset stable range of the rated voltage and exceeds the third preset time.

[0057] Based on the voltage stabilization signal, each slave unit is sorted according to its priority score, and the input order is determined from high to low.

[0058] Calculate the specific delayed input time for each unit based on the input order;

[0059] After each slave unit reaches its corresponding delayed start time, it controls its converter to connect to the DC bus and switches the control mode from standby mode to network construction mode to complete the construction of the isolated network.

[0060] Furthermore, this application also discloses a start-up control system for islanded energy storage networks using a fully DC combined grid configuration, comprising:

[0061] A monitoring module is used to monitor whether the grid-type energy storage system is in a dormant state, wherein the grid-type energy storage system includes multiple energy storage units;

[0062] The calculation module is used to send a distributed negotiation command with its own status information to all other multiple energy storage units when the grid-type energy storage system is in a dormant state, and to receive its own status information from all other multiple energy storage units. Each energy storage unit calculates a priority score based on all its own status information and sends the priority score to other energy storage units. The connection between multiple energy storage units and the DC bus is interrupted.

[0063] The pressure-building module is used to select the corresponding target energy storage unit as the main start-up unit based on all priority scores, and the remaining energy storage units as slave units.

[0064] The main start-up unit executes an adaptive soft-start algorithm to pre-charge the DC bus connected to the grid-type energy storage system so that the DC bus voltage reaches the rated value.

[0065] The judgment module is used to enable each slave unit to monitor whether the startup status of the main startup unit meets the preset conditions according to preset requirements;

[0066] The reselection module is used to send a fault-tolerant reselection command to all other slave units when the preset conditions are not met.

[0067] Each slave unit reselects a target master boot unit according to the fault-tolerant reselection instruction;

[0068] The construction module is used to enable all energy storage units except the main start-up unit to re-establish electrical connections with the DC bus based on their own converters and form voltage regulation when preset conditions are met, so as to complete the construction of the islanded grid.

[0069] This application also provides a computer device, including a memory and a processor, wherein the memory stores a computer program, and the processor executes the computer program to implement the steps of the above-described method for starting up an isolated grid of energy storage suitable for all-DC converged grid construction.

[0070] This application also provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the steps of the above-described method for starting up an islanded energy storage grid applicable to a full DC converged grid structure.

[0071] The beneficial effects of this application are as follows:

[0072] This application eliminates the reliance on traditional centralized controllers through a coherent process of state monitoring, distributed election, soft-start algorithm, fault-tolerant re-election, and orderly access of slave units. It enables islanded self-starting of the grid-connected energy storage system after disconnection from the main grid. Through autonomous collaboration among the energy storage units, a suitable master start-up unit is dynamically elected to undertake the core voltage-building task. Simultaneously, a built-in fault-tolerant mechanism effectively addresses the negative impacts of master unit failure. Finally, slave units and loads are accessed in an orderly manner, ensuring that the grid-connected energy storage system can reliably complete islanded grid construction even in scenarios without a central node or with partial equipment failure. This solves the problems of single-point failure, slow dynamic response, and low reliability inherent in traditional centralized start-up systems, meeting the islanded grid start-up requirements of all-DC aggregation systems. Attached Figure Description

[0073] Figure 1 This is a schematic diagram of a method flow proposed in an embodiment of this application.

[0074] Figure 2 This is a schematic diagram of the system structure proposed in one embodiment of this application.

[0075] Figure 3 This is a schematic diagram of the internal structure of a computer device according to an embodiment of this application.

[0076] The realization of the purpose, functional features and advantages of this application will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0077] It should be understood that the specific embodiments described herein are merely illustrative of this application and are not intended to limit this application.

[0078] like Figure 1 As shown, this application provides a start-up control method for islanded energy storage networks using a fully DC-connected grid, comprising the following steps:

[0079] S1, monitor whether the grid-type energy storage system is in a dormant state, wherein the grid-type energy storage system includes multiple energy storage units;

[0080] S2, If it is in a dormant state, each energy storage unit sends a distributed negotiation instruction with its own status information to all other multiple energy storage units, and receives its own status information from all other multiple energy storage units. Each energy storage unit calculates a priority score based on all its own status information and sends the priority score to other energy storage units. In this case, the connection between multiple energy storage units and the DC bus is interrupted.

[0081] S3, each energy storage unit selects the corresponding target energy storage unit as the main start-up unit according to all priority scores, and the remaining energy storage units are the slave units;

[0082] The main starting unit executes an adaptive soft-start algorithm to pre-charge the DC bus connected to it so that the DC bus voltage reaches the rated voltage.

[0083] S4, each of the slave units monitors whether the startup status of the main startup unit meets the preset conditions according to preset requirements;

[0084] S5, if the preset conditions are not met, each slave unit sends a fault-tolerant reselection instruction to all other slave units;

[0085] Each slave unit reselects a target master boot unit according to the fault-tolerant reselection instruction;

[0086] S6. If the preset conditions are met, all slave units will re-establish electrical connections with the DC bus based on their own converters and form voltage build-up to complete the construction of the isolated network.

[0087] As described in steps S1-S6 above, with the continuous expansion of the scale of new energy power generation, all-DC grid-connected energy storage systems with photovoltaic and energy storage as the core have become an important form of new energy bases. After such systems are disconnected from the main grid, the DC bus will experience a loss of voltage. However, some important loads need to be continuously powered. Therefore, they must have reliable islanded grid start-up capability to restore power supply. At the same time, there may be equipment failure risks during the operation of grid-connected energy storage systems. If the core equipment fails during the start-up process, there must be a mechanism to ensure that the start-up process is not interrupted and to avoid the paralysis of the entire system. This requires the start-up control method to be able to achieve orderly start-up after voltage loss and to cope with equipment failure.

[0088] Existing isolated grid start-up control methods rely on a centralized controller. This controller needs to monitor the status of the grid-type energy storage system in real time and then designate a converter of a certain energy storage unit to establish the DC bus voltage first according to preset logic, and then put other equipment into operation in sequence. This method has a significant risk of single point of failure. Once the central controller fails or the designated start-up unit fails, the entire start-up process will fail completely. Moreover, in a fully DC-connected system with widely distributed equipment and a wide coverage area, communication delays and equipment heterogeneity will reduce the dynamic response speed and reliability of centralized control, and cannot meet the requirements of high resilience and self-organized start-up of the system.

[0089] This application focuses on distributed autonomous collaboration. First, a consensus mechanism across all units triggers the startup process. Each energy storage unit synchronously monitors the DC bus voltage and jointly determines whether to enter a dormant state. Each unit exchanges information such as state of charge, rated capacity, and electrical distance through distributed communication to elect the highest priority master startup unit, replacing the traditional designated mode to avoid single-point dependency risks. The elected master startup unit executes an exponentially growing adaptive soft-start algorithm, combined with loop parameters to control the voltage rise smoothly, and uses current closed-loop limiting to avoid impact damage to equipment, achieving safe and efficient DC bus voltage build-up. During the voltage build-up process, slave units use a dual mechanism of voltage compliance monitoring and heartbeat signal listening to judge the master unit status in real time. Once a master unit failure is detected, a rapid re-election process is immediately initiated to continue startup, ensuring uninterrupted fault operation. After the DC bus voltage stabilizes, each slave unit connects to the main bus sequentially with a short delay to achieve staggered peak operation to disperse inrush current, ultimately completing the islanded grid construction and forming a highly resilient islanded grid startup scheme that does not rely on a central controller.

[0090] In one embodiment, the step of monitoring whether the grid-type energy storage system is in a dormant state includes:

[0091] S11, monitor the DC bus voltage of the grid-type energy storage system, collect the original voltage data of the DC bus at the connection point between each energy storage unit and the DC bus, and simultaneously collect the frequency fluctuation data of the grid-type energy storage system and the output power change rate of each energy storage unit.

[0092] S12, obtain the preset voltage threshold, frequency stability threshold and power change rate threshold of the grid-type energy storage system;

[0093] S13, the original voltage data is processed to obtain the filtered voltage value. At the same time, the frequency fluctuation data is subjected to sliding window variance analysis to obtain the frequency stability index, and the output power change rate is subjected to trend fitting to obtain the power attenuation slope.

[0094] S14, compare the filtered voltage value with the voltage threshold, compare the frequency stability index with the frequency stability threshold, and compare the power attenuation slope with the power change rate threshold.

[0095] S15, based on the fuzzy logic algorithm, the voltage comparison results, frequency stability comparison results and power attenuation comparison results are fused and calculated to obtain the system silence confidence.

[0096] S16, if the system's quiescent confidence level exceeds a preset confidence threshold and the duration exceeds a first preset time, then the grid-type energy storage system is determined to have entered a quiescent state.

[0097] As described in steps S11-S16 above, by collecting multi-dimensional system operation data, processing data to quantify characteristic indicators, fusion of multiple results to calculate the dormancy confidence level, and combining the determination of duration, the dormancy state of the grid-type energy storage system can be identified with high accuracy and low misjudgment. This ensures that the subsequent distributed negotiation process is only triggered when the grid-type energy storage system is truly in a stable state of pressure loss that requires isolated grid startup.

[0098] After existing all-DC grid-connected energy storage systems are disconnected from the main grid, the DC bus may enter a state of undervoltage. However, during the undervoltage process, it is susceptible to electromagnetic interference from the lines and transient errors in sensors, resulting in brief voltage jumps. If the state is determined directly based on the original voltage data, misjudgment will occur. If it is misjudged as not being dormant, the startup opportunity will be missed; if it is misjudged as being dormant, unnecessary negotiation processes will be triggered, wasting system resources. At the same time, each energy storage unit in the distributed system needs to synchronously confirm the dormant state to ensure the orderly start of the negotiation process. If some units fail to detect dormancy or delay confirmation, it will cause negotiation chaos.

[0099] This application monitors the DC bus voltage of a grid-type energy storage system, collects raw voltage data of the DC bus at the connection point between each energy storage unit and the DC bus, and simultaneously collects frequency fluctuation data and the output power change rate of each energy storage unit. System frequency data is collected by the local frequency monitoring module of each energy storage unit, and the output power change rate is calculated from continuously sampled output power data to obtain preset voltage thresholds, frequency stability thresholds, and power change rate thresholds for the grid-type energy storage system. The voltage threshold is set based on the system's rated DC bus voltage, the frequency stability threshold is set based on the grid's rated frequency, and the power change rate threshold is set based on the rated power of the energy storage unit.

[0100] The raw voltage data is processed to obtain the filtered voltage value. Simultaneously, a sliding window variance analysis is performed on the frequency fluctuation data to obtain a frequency stability index. Furthermore, a trend fit is performed on the output power change rate to obtain the power attenuation slope. The raw voltage data is processed using a moving average filtering algorithm with a 50ms time window to eliminate instantaneous interference. The variance of the frequency fluctuation data is calculated using a 1-second sliding window; a larger variance indicates greater frequency instability, forming the frequency stability index. The output power change rate is fitted with a linear trend to obtain the power attenuation slope value, quantifying the power attenuation rate. The filtered voltage value is compared with a voltage threshold, the frequency stability index is compared with a frequency stability threshold, and the power attenuation slope is compared with a power change rate threshold. If the filtered voltage value is below 0.5kV, the voltage comparison result indicates a voltage loss characteristic; otherwise, it indicates a normal characteristic. If the variance corresponding to the frequency stability index exceeds the variance range of 48Hz-52Hz, it is an unstable feature; otherwise, it is a stable feature. If the power attenuation slope is less than -0.5pu / s, it is an attenuation feature; otherwise, it is a normal feature. By comparing the three types of indicators pairwise, the state characteristics of each dimension are selected.

[0101] Based on a fuzzy logic algorithm, the voltage comparison results, frequency stability comparison results, and power attenuation comparison results are fused to obtain the system quiescent confidence level. The input to the fuzzy logic algorithm is the feature membership degree corresponding to the three types of comparison results, such as a voltage loss feature membership degree of 0.9, a frequency instability feature membership degree of 0.8, and a power attenuation feature membership degree of 0.95. The output is the quiescent confidence level in the 0-1 range. The membership function and fuzzy rules are preset during system design. For example, when all three features are instability-related, the confidence level output is above 0.9; when only one feature is instability-related, the confidence level output is below 0.3. By fusing multi-dimensional features, the certainty of the system being in a quiescent state is quantified, avoiding misjudgment based on a single feature. If the system quiescent confidence level exceeds a preset threshold and the duration exceeds a first preset time, the grid-type energy storage system is determined to have entered a quiescent state. The preset threshold is set to 0.8, and the first preset time is set to 5 seconds to ensure that the system is in a highly deterministic unstable state and remains stable, rather than fluctuating momentarily, thus avoiding erroneous operations triggered by momentary anomalies.

[0102] In one embodiment, the step of calculating a priority score for each energy storage unit based on all its own state information includes:

[0103] S21, extract the state of charge, rated capacity and electrical distance parameters from the system core bus from the self-state information;

[0104] S22, Identify the current operating mode of the grid-type energy storage system, the operating mode including fast recovery mode, stable operation mode and economic operation mode;

[0105] S23, based on the identified operating mode category, perform modal adaptation reconstruction on the self-state information, including:

[0106] In the fast recovery mode, the state of charge value is reconstructed to the maximum supportable power value;

[0107] Under stable operating conditions, the rated capacity value is reconstructed into a capacity stability coefficient;

[0108] Under the economic operation mode, the electrical distance parameter is reconstructed into a transmission efficiency factor;

[0109] S24. Based on the reconstructed self-state information, establish a multimodal competitive scoring matrix and calculate the modal fit score of each energy storage unit under different operating modes.

[0110] S25. Based on the mode adaptability score of each energy storage unit in the current operating mode, and combined with the relative ranking in other operating modes, calculate the mode competitive advantage value.

[0111] S26, Based on the modal competitive advantage value, generate the final priority score;

[0112] S27, each energy storage unit broadcasts the priority score as part of the distributed negotiation instruction to all other energy storage units.

[0113] As described in steps S21-S27 above, by extracting the core state parameters of the energy storage unit, identifying the system operating modes, reconstructing the adaptation parameters, establishing a multimodal scoring matrix, and calculating the competitive advantage value, a priority score that adapts to the current operating scenario is finally generated, ensuring that the selected main start-up unit can optimally match the core needs of the system in different scenarios such as rapid recovery, stable operation, or economical operation.

[0114] The islanded startup requirements of all-DC converged grid-connected energy storage systems change dynamically depending on the scenario. In the event of a sudden main grid failure, the system needs to quickly restore power supply; in this case, the instantaneous power support capability of the energy storage units is crucial. During long-term stable operation of the islanded grid, capacity stability determines the continuity of power supply. In scenarios requiring reduced energy consumption, energy transfer efficiency is even more critical. Using a fixed-weighted priority score calculation can lead to the selection of units with high charge but slow power output in rapid recovery scenarios, delaying startup; and the selection of units with strong power but small capacity in stable operation scenarios, which cannot provide long-term support.

[0115] The system identifies the current operating modes of a grid-connected energy storage system, including fast recovery mode, stable operation mode, and economic operation mode. Mode identification is based on the type of event that triggers the islanding of the system. A sudden power outage in the main grid with an emergency load is classified as fast recovery mode; long-term power supply after islanding activation is classified as stable operation mode; and minimizing transmission losses is prioritized during islanding operation, classifying it as economic operation mode. Identification logic is pre-installed in each energy storage unit, ensuring consensus among all units on the current mode by analyzing system status signals.

[0116] Based on the identified operating mode category, the system performs mode adaptation reconstruction of its own state information. In the fast recovery mode, the state of charge value is reconstructed into the maximum supportable power value, calculated using the following formula: ,in, Indicates the maximum supported power. The state of charge (SCC) is represented by 'w', and the rated power (RW) directly reflects the instantaneous power supply capacity of the unit. Under stable operating mode, the rated capacity value is reconstructed into a capacity stability coefficient, calculated using historical charge / discharge capacity fluctuations. For example, a unit with a capacity fluctuation of ±2% has a coefficient of 0.98. Under economic operating mode, the electrical distance parameter is reconstructed into a transmission efficiency factor; the closer the distance, the higher the factor (0.95 for 100 meters, 0.8 for 500 meters), quantifying the impact of transmission losses. Based on the reconstructed self-state information, a multi-modal competitive scoring matrix is ​​established to calculate the mode fit score of each energy storage unit under different operating modes. Rows in the matrix represent energy storage units, and columns represent operating modes. Each element is the score for that unit in the corresponding mode. The scoring uses a 10-point scale. Under fast recovery mode, units are sorted by maximum supported power, with the highest power unit receiving 10 points, decreasing sequentially. Under stable operating mode, units are sorted by capacity stability coefficient, with the highest coefficient receiving 10 points. Under economic operating mode, units are sorted by transmission efficiency factor, with the highest factor receiving 10 points. For example, a certain unit scores 10 points for having the highest power in the fast recovery mode, 8 points for ranking second in the stable operation mode coefficient, and 6 points for ranking third in the economic operation mode factor. The matrix clearly shows its adaptability in each mode.

[0117] Based on the mode fit score of each energy storage unit in the current operating mode, and combined with its relative ranking in other operating modes, the mode competitive advantage value is calculated. The calculation formula is as follows:

[0118] ;

[0119] in, This represents the modal competitive advantage value. This indicates the modality fit score. This indicates the average ranking of other modalities. This indicates that the average ranking of other modalities is the lowest. This represents the adaptability weighting coefficient. If the current mode is fast recovery, and a certain energy storage unit currently scores 10 points, ranking 2nd and 3rd in the stable and economic modes respectively (out of 5 units), then the average reciprocal ranking of other modes is ((5-2+1) / 5+(5-3+1) / 5) / 2=(4 / 5+3 / 5) / 2=0.7. Therefore, the mode competitive advantage value = 10+0.7×2=11.4. This calculation highlights the core adaptability of the current mode while also taking into account the unit's comprehensive capabilities in other modes, avoiding the selection of energy storage units with strong single capabilities but poor overall adaptability.

[0120] In one embodiment, the main starting unit executes an adaptive soft-start algorithm to pre-charge the DC bus connected to it so that the DC bus voltage reaches the rated voltage. The steps include:

[0121] S31, Each energy storage unit compares all priority scores and determines the energy storage unit with the highest priority score as the target energy storage unit;

[0122] S32, set the target energy storage unit as the master start-up unit, and the other energy storage units as slave units;

[0123] S33, the main starting unit obtains the control parameters of its converter, including the rated voltage, time constant and maximum allowable current;

[0124] S34, according to the control parameters, the main start-up unit executes an adaptive soft-start algorithm to bring the DC bus into a voltage establishment state:

[0125] S35, the main starting unit controls the voltage output of its converter to the DC bus to start from zero and gradually approach the rated voltage in an exponential growth pattern.

[0126] S36, during the voltage rise process, the main start-up unit samples the DC bus charging current in real time and limits the current to below the maximum allowable current so that the DC bus voltage reaches the rated voltage;

[0127] S37, the master startup unit periodically sends heartbeat signals to each slave unit.

[0128] As described in steps S31-S37 above, the main start-up unit acquires the converter control parameters, executes the adaptive soft start algorithm according to the exponential growth law, controls the charging current in a closed loop, and synchronously monitors the voltage and heartbeat signal from the slave unit to achieve a stable pre-charge establishment of the DC bus voltage, avoid voltage surge damage to the equipment, and at the same time ensure that the working status of the main start-up unit can be monitored, providing safety and reliability assurance for the core voltage building-up link of islanded grid start-up.

[0129] The DC bus circuit contains numerous capacitors, such as filter capacitors and converter support capacitors. The voltage across these capacitors cannot change abruptly. If the main starting unit controls the converter to directly output its rated voltage, it will cause a sudden surge in capacitor charging current, potentially leading to overcurrent damage to the converter or capacitor breakdown. Simultaneously, the voltage rise rate needs to be controlled in real-time during the voltage build-up process. An excessively fast rate will exacerbate electromagnetic oscillations in the circuit, while an excessively slow rate will prolong the startup time, affecting the timeliness of load power supply. Furthermore, the main starting unit may fail due to component malfunction during the pre-charging phase. If the slave unit does not synchronously monitor its status, it will continue to wait, causing the startup process to stall.

[0130] The main starting unit acquires the control parameters of its converter, including rated voltage, time constant, and maximum allowable current. The rated voltage is determined according to design standards, for example, the rated voltage of the DC bus is 10kV. The time constant is calculated based on the capacitor capacity and loop impedance and is used to control the voltage rise rate. The maximum allowable current is set according to the converter's rated current and the equipment's withstand capability. These parameters are read by the main starting unit through a local parameter storage module to ensure that they match the converter's hardware performance.

[0131] Based on the control parameters, the main starting unit executes an adaptive soft-start algorithm to bring the DC bus into a voltage establishment state. The voltage establishment state means that the main starting unit executes the adaptive soft-start algorithm to control its converter output voltage to gradually approach the rated voltage from zero using an exponential growth law, where the voltage rise rate is controlled by a time constant. The formula for the exponentially growing voltage output is:

[0132] ;

[0133] in, This represents the output voltage at time t. Indicates the rated voltage. This is a time constant. For example, the voltage is 0 at t=0, and rises to 10kV × (1- ) seconds later (1 time constant). The voltage is approximately 6.32kV. When t=6 seconds (3 time constants), the voltage is close to 10kV. This pattern allows the voltage to rise smoothly, avoiding capacitor charging impact. At the same time, the time constant determines the rise rate, ensuring a balance between voltage regulation efficiency and safety.

[0134] During voltage rise, the main starting unit samples the DC bus charging current in real time and uses a closed-loop control algorithm to limit the current below the maximum allowable current, ensuring the DC bus voltage reaches its rated voltage. When the sampled current approaches the maximum allowable current of 480A, the algorithm automatically reduces the voltage rise rate, decreasing the converter output voltage increase. For example, it reduces the original rise rate of 2kV per second to 1kV per second, causing the current to drop below 450A. When the current falls below the limit, the normal rise rate is restored, and dynamic adjustment ensures the current never exceeds 500A, protecting the converter and capacitor equipment.

[0135] The master start-up unit periodically sends heartbeat signals to each slave unit. The slave units collect DC bus voltage via local voltage sensors to determine in real time whether the voltage is rising as expected. The master start-up unit sends heartbeat signals via a distributed communication network at a fixed interval of 1 second. The heartbeat signal contains the master unit ID and the current voltage value. The heartbeat signal, sent periodically and repeatedly by the master start-up unit to all slave units via the communication network, indicates that the master unit is operating normally and includes the master unit ID and the current voltage value; its function is fault detection. Slave units can use this heartbeat signal to know that the master unit is in normal working condition. A normal heartbeat signal proves that the master unit's control system and communication module are operating normally. In this application, if a slave unit does not receive a valid signal for three consecutive heartbeat cycles (3 seconds), or detects a stall in voltage rise (e.g., the voltage does not rise from 6kV to 7kV within 5 seconds), it preliminarily determines that the master start-up unit is abnormal, and the slave unit can infer that the master unit has failed. At this point, a fault-tolerant re-election instruction will be triggered.

[0136] In one embodiment, the step of each slave unit monitoring whether the startup status of the master startup unit meets preset conditions according to preset requirements includes:

[0137] S41, each slave unit continuously monitors the DC bus voltage establishment status and determines whether the DC bus voltage reaches the preset stable range of the rated voltage within the second preset time.

[0138] S42, each slave unit continuously monitors the heartbeat signal periodically broadcast by the master startup unit and determines whether the slave unit has received a valid signal within a preset number of consecutive times;

[0139] S43. If the DC bus voltage does not reach the preset stable range within the second preset time, or if the heartbeat signal is lost for a preset number of consecutive times, it is determined that the preset condition is not met.

[0140] S44. If the DC bus voltage reaches a stable range within a second preset time and a valid heartbeat signal is received within a preset number of times, then the preset condition is determined to be met.

[0141] As described in steps S41-S44 above, by continuously monitoring the DC bus voltage establishment status and the heartbeat signal of the main start-up unit from the unit, and combining the dual judgment logic of time and signal count, it is possible to accurately identify whether the start-up status of the main start-up unit meets the preset conditions, so as to ensure that the islanded grid start-up process proceeds smoothly when the main unit is normal and responds in a timely manner when the main unit is abnormal, thereby avoiding start-up interruption or misoperation.

[0142] During the voltage build-up process of the main startup unit executing the adaptive soft-start algorithm, voltage build-up may fail due to issues such as converter failure or charging current over-limit protection tripping. It may also fail due to communication module failure causing heartbeat signal interruption. Both situations will cause islanded startup to stall. If only a single indicator is used for judgment, a slow voltage build-up speed that is still progressing normally may be misjudged as a startup anomaly, triggering unnecessary reselection. If only the heartbeat signal is monitored, it is susceptible to transient communication interference.

[0143] The second preset time is set based on the main start-up unit's voltage regulation algorithm and the system's capacitor capacity. For example, if the main start-up unit needs 10 seconds to approach the rated voltage according to an exponential growth law, the second preset time is set to 10 seconds. The stable voltage threshold is set based on the rated voltage and the voltage regulation completion standard. The system's rated DC bus voltage is 10kV, so the stable voltage threshold is set to 9.5kV, which is 95% of the rated voltage. If the voltage does not reach 9.5kV within 10 seconds, it is preliminarily determined that the main start-up unit's voltage regulation is abnormal.

[0144] The main start-up unit sends heartbeat signals to each slave unit via a distributed communication network at a fixed interval, such as once per second. If the DC bus voltage fails to reach a preset stable range within a second preset time, or if a preset number of heartbeat signals are lost consecutively, the preset conditions are deemed not met. Slave units are set to receive heartbeat signals. If a heartbeat signal containing a valid ID and voltage information is not received for three consecutive heartbeat cycles (3 seconds), the preset conditions are deemed not met, i.e., the heartbeat signal is lost. Furthermore, an OR logic is used for judgment; failure is determined as long as either condition is met. For example, if the voltage rises to only 3kV after 5 seconds of voltage stabilization by the main start-up unit (meaning it cannot reach 9.5kV within 10 seconds), or if no heartbeat signal is received for three consecutive seconds, the slave unit is deemed to have failed. This dual-judgment logic covers both voltage stabilization function failure and device failure scenarios, encompassing various failure situations that the main start-up unit may experience, and avoiding the omission of faults by a single judgment.

[0145] In one embodiment, if the preset conditions are not met, each slave unit sends a fault-tolerant reselection instruction to all other slave units, and the step of each slave unit reselecting the target master boot unit according to the fault-tolerant reselection instruction includes:

[0146] S51, if the preset conditions are not met, each slave unit analyzes the triggering factors of the main start-up unit failure, including DC bus voltage regulation failure characteristics, heartbeat signal loss mode and failure occurrence time characteristics.

[0147] S52, establish a re-election mode recognition mechanism based on the triggering factors, and determine the re-election strategy according to the voltage regulation failure characteristics and heartbeat signal loss mode. The re-election strategy includes a fast recovery mode and a smooth switching mode.

[0148] S53, In fast recovery mode, each slave unit calls the preset dynamic capability profile data, which is constructed based on the historical startup success rate, voltage support response time and current environmental adaptability of each unit.

[0149] S54, Based on the dynamic capability profile data, the emergency situation assessment algorithm is used to directly generate the emergency priority score of the candidate unit, thereby skipping the conventional priority score calculation step.

[0150] S55, in smooth switching mode, each slave unit constructs a cooperative operation matching matrix based on the rated capacity coordination of each unit and the similarity of converter control characteristics, and calculates the cooperative operation efficiency value between units.

[0151] S56. Based on the identified re-election mode, select the corresponding evaluation data. In the rapid recovery mode, the emergency priority score is used, and in the smooth switching mode, the collaborative operation efficiency value is used.

[0152] S57, based on the selected evaluation data, executes a rapid election process to determine the slave unit with the highest emergency priority score or collaborative operation efficiency score in the corresponding mode as the new master startup unit.

[0153] As described in steps S51-S57 above, by analyzing the failure triggering factors of the main boot unit, identifying the re-election mode, adapting the evaluation data of different modes, and performing fast election, the scenario-based rapid reconstruction after the failure of the main boot unit is realized, ensuring that a new suitable main boot unit can be efficiently selected under different failure scenarios, avoiding orphanage boot interruption, while taking into account both boot speed and system stability.

[0154] The failure scenarios of the main start-up unit differ significantly. In the initial stage of voltage build-up, a sudden short circuit in the converter may cause a sharp voltage drop and a sudden loss of the heartbeat signal. At this time, the islanded grid has no voltage support, and voltage build-up needs to be restored as quickly as possible to avoid delays in emergency load power supply. In the later stage of voltage build-up, failure may occur due to the voltage slowly failing to reach a stable range. At this time, the DC bus already has a certain voltage, and a smooth switchover to a new main unit is required to avoid voltage surges damaging capacitors and other equipment. If a unified re-election process is adopted, a fast process may cause a surge in failures in the later stages, while a smooth process may cause delays in failures in the initial stages.

[0155] The triggering factors originate from the DC bus voltage data and heartbeat signal reception records continuously monitored by the slave unit. Voltage regulation failure characteristics include sudden voltage drop or gradual failure to meet standards. Heartbeat signal loss patterns include sudden loss or gradual loss. The failure occurrence time characteristic is the time elapsed between the failure and the start of soft start. Based on the voltage regulation failure characteristics and heartbeat signal loss patterns, a re-election strategy is determined. The identification mechanism matches scenarios through preset logic. If the failure occurs 3 seconds before soft start, with a sudden voltage drop and sudden loss of heartbeat, it is determined to be a fast recovery mode to shorten the recovery time. If the failure occurs after 5 seconds of soft start, with a slow voltage failure and gradual loss of heartbeat, it is determined to be a smooth switching mode to avoid voltage surges. The above logic is pre-installed on the local controller of each slave unit to ensure that all units synchronously identify the mode.

[0156] Historical startup success rate is the ratio of the number of successful isolated network startups stored locally in each unit to the total number of startups. Voltage support response time is the delay time from receiving a command to outputting voltage. Current environmental adaptability is evaluated using data collected from local temperature and humidity sensors. Based on dynamic capability profile data, an emergency situation assessment algorithm is used to directly generate emergency priority scores for candidate units, skipping the conventional priority score calculation step. The emergency situation assessment algorithm uses weighted summation logic, with weights set according to emergency needs. Historical startup success rate is 0.5, voltage support response time is 0.3, and current environmental adaptability is 0.2. For example, a unit with a success rate of 0.9, a response time of 0.5 seconds (normalized to 0.8), and an adaptability of 0.9 has an emergency priority score of 0.9 × 0.5 + 0.8 × 0.3 + 0.9 × 0.2 = 0.83, which can be directly output, eliminating conventional steps such as modality recognition and parameter reconstruction, thus shortening computation time.

[0157] In smooth switching mode, each slave unit constructs a cooperative operation matching matrix based on the rated capacity coordination of each unit and the similarity of converter control characteristics, and calculates the cooperative operation efficiency value between units. Rated capacity coordination is the percentage difference between the rated capacity of the candidate unit and the original master starting unit. Converter control characteristic similarity is calculated through the difference in parameters such as droop coefficient and response bandwidth. The rows and columns of the cooperative operation matching matrix are candidate units, and the elements are the cooperative values ​​of each pair of units. The cooperative operation efficiency value is the average of the cooperative values ​​of a unit with all other candidate units.

[0158] The matching logic between the mode and the evaluation data is pre-installed in the slave unit, ensuring that all energy storage units are evaluated using the same standards. Based on the selected evaluation data, a fast election process is executed, and the newly elected master start-up unit can immediately take over the pressure-building task, avoiding startup interruption.

[0159] In one embodiment, if preset conditions are met, the steps for all slave units to re-establish electrical connections with the DC bus based on their own converters and form voltage regulation to complete the construction of the islanded grid include:

[0160] S61, if the preset conditions are met, each slave unit obtains a DC bus voltage stabilization signal and determines whether the DC bus voltage is maintained within the preset stable range of the rated voltage and exceeds the third preset time.

[0161] S62, based on the voltage stabilization signal, each slave unit is sorted according to its priority score, and the input order is determined from high to low.

[0162] S63, calculate the specific delayed input time for each slave unit according to the input order; wherein, the slave unit with the higher priority score has a shorter delayed input time;

[0163] S64. After each slave unit reaches its corresponding delayed start time, each slave unit controls its converter to connect to the DC bus and switches the control mode from standby mode to network construction mode to complete the construction of the isolated network.

[0164] As described in steps S61-S64 above, by judging the DC bus voltage stability from the unit, determining the unit input order according to priority score, calculating the delayed input time, controlling the unit access and switching mode, inputting new energy and load and monitoring system stability, the complete construction of orderly access of the DC bus and islanded grid system from the unit is realized, avoiding voltage fluctuations caused by the synchronous access of multiple units.

[0165] When the DC bus voltage is first established, although it has reached the rated voltage, there may be slight fluctuations. If multiple slave units connect simultaneously at this time, the converter of each slave unit will generate an inrush current upon connection. The superposition of these currents may cause a sudden drop in the bus voltage, disrupting the established voltage stability. Furthermore, different slave units have different states of charge and rated capacities. Units with higher priority scores are better able to support the bus voltage; prioritizing their connection can quickly enhance the bus voltage support and reduce the impact of subsequent unit connections. In addition, after a slave unit connects, it needs to switch to a grid-based control mode to participate in bus voltage and frequency regulation. If the mode switch is not timed properly or the load is connected before the switch is complete, the system will lose its voltage support capability.

[0166] The rated voltage is set to 10kV according to the system design, the preset stability range is set to ±2% of the rated voltage, and the third preset time is set to 3 seconds based on the voltage fluctuation attenuation characteristics. The unit continuously monitors whether the DC bus voltage is within the range of 9.8kV-10.2kV within 3 seconds. If it meets the requirements, the voltage is considered stable. If the voltage exceeds the range at any moment within 3 seconds, it continues to wait until the conditions are met to avoid connection during voltage fluctuations.

[0167] Units with higher priority scores are put into service first. The priority score of a unit is calculated during the distributed negotiation phase using a weighted average of normalized parameters such as state of charge, rated capacity, and electrical distance. For example, PCS1 has a priority score of 0.86, while PCS3 has a priority score of 0.76; therefore, PCS1 is put into service before PCS3. This prioritization method ensures that units with strong support capabilities are connected first, rapidly enhancing the bus voltage support strength and reducing the impact of lower-priority units being connected.

[0168] Based on the input order, the specific delayed input time for each slave unit is calculated. The slave unit delayed input time is set according to the priority score difference, which is the difference between the priority score of a slave unit and the score of the highest priority slave unit. The formula for calculating the slave unit delayed input time is as follows:

[0169] ;

[0170] in, Indicates the unit delay time. This represents the reference delay time, which is a system preset value and can be set according to the total number of slave units. Indicates the priority score difference. This represents the delay adjustment coefficient, which can be set based on the matching relationship between the priority score difference and the delay reduction magnitude. For example, if the score difference between PCS1 (score 0.86) and PCS3 (score 0.76) is 0.1, the delay activation time of PCS1 is set to 1 second, and the delay activation time of PCS3 is set to 1.5 seconds. By staggering the peak delay access, multiple slave units are prevented from accessing at the same time, thus dispersing the time of inrush current generation and preventing the superposition of inrush currents from causing large fluctuations in bus voltage.

[0171] After the local controller of each slave unit finishes its delay period, it sends a converter connection command to control the converter to gradually increase its output current and smoothly connect to the bus. Simultaneously, it sends a mode switching command to switch the converter from standby mode to grid-connected control mode. In this mode, the converter uses a droop control algorithm to adjust its output voltage based on the bus voltage deviation and its output power based on the frequency deviation, participating in supporting the islanded grid voltage and frequency. Load connection is also implemented gradually, for example, from 0 to 60% of the rated load, and then to 100%. During the connection process, the bus voltage and frequency are monitored in real time through the grid-connected control mode of each slave unit. If the voltage or frequency exceeds the range, the slave unit immediately adjusts its output to ensure the stable operation of the islanded grid system and complete its construction.

[0172] like Figure 2 As shown, this application also discloses a start-up control system for islanded energy storage networks with all-DC converged grids, comprising:

[0173] A monitoring module is used to monitor whether the grid-type energy storage system is in a dormant state, wherein the grid-type energy storage system includes multiple energy storage units;

[0174] The calculation module is used to send a distributed negotiation command with its own status information to all other multiple energy storage units when the grid-type energy storage system is in a dormant state, and to receive its own status information from all other multiple energy storage units. Each energy storage unit calculates a priority score based on all its own status information and sends the priority score to other energy storage units. The connection between multiple energy storage units and the DC bus is interrupted.

[0175] The pressure-building module is used to select the corresponding target energy storage unit as the main start-up unit based on all priority scores, and the remaining energy storage units as slave units.

[0176] The main start-up unit executes an adaptive soft-start algorithm to pre-charge the DC bus connected to the grid-type energy storage system so that the DC bus voltage reaches the rated value.

[0177] The judgment module is used to enable each slave unit to monitor whether the startup status of the main startup unit meets the preset conditions according to preset requirements;

[0178] The reselection module is used to send a fault-tolerant reselection command to all other slave units when the preset conditions are not met.

[0179] Each slave unit reselects a target master boot unit according to the fault-tolerant reselection instruction;

[0180] The construction module is used to enable all energy storage units except the main start-up unit to re-establish electrical connections with the DC bus based on their own converters and form voltage regulation when preset conditions are met, so as to complete the construction of the islanded grid.

[0181] like Figure 3 As shown, this application also provides a computer device, which can be a server, and its internal structure can be as follows: Figure 3As shown, the computer device includes a processor, memory, network interface, and database connected via a system bus. The processor provides computational and control capabilities. The memory includes non-volatile storage media and internal memory. The non-volatile storage media stores the operating system, computer programs, and database. The internal memory provides an environment for the operation of the operating system and computer programs stored in the non-volatile storage media. The database stores all data required for the process of the grid-based energy storage power balance control method based on a hierarchical collaborative strategy. The network interface is used for communication with external terminals via a network connection. When the computer program is executed by the processor, it implements the grid-based energy storage power balance control method based on a hierarchical collaborative strategy.

[0182] Those skilled in the art will understand that Figure 3 The structure shown is merely a block diagram of a portion of the structure related to the present application and does not constitute a limitation on the computer equipment on which the present application is applied.

[0183] This application also provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the steps of the above-described method for starting up an islanded energy storage grid applicable to a full DC converged grid structure.

[0184] Those skilled in the art will understand that all or part of the processes in the above embodiments can be implemented by a computer program instructing related hardware. The computer program can be stored in a non-volatile computer-readable storage medium. When executed, the computer program can include the processes of the embodiments of the above methods. Any references to memory, storage, databases, or other media used in this application and in the embodiments can include non-volatile and / or volatile memory. Non-volatile memory can include read-only memory (ROM), programmable ROM (PROM), electrically programmable ROM (EPROM), electrically erasable programmable ROM (EEPROM), or flash memory. Volatile memory can include random access memory (RAM) or external cache memory. By way of illustration and not limitation, RAM is available in a variety of forms, such as static RAM (SRAM), dynamic RAM (DRAM), synchronous DRAM (SDRAM), dual-speed SDRAM (SSRSDRAM), enhanced SDRAM (ESDRAM), synchronous link DRAM (SLDRAM), RAMbus direct RAM (RDRAM), direct memory bus dynamic RAM (DRDRAM), and memory bus dynamic RAM (RDRAM).

[0185] It should be noted that, in this document, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, apparatus, article, or method that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, apparatus, article, or method. Unless otherwise specified, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, apparatus, article, or method that includes that element.

[0186] The above description is merely a preferred embodiment of this application and does not limit the scope of this application. Any equivalent results or equivalent process transformations made based on the content of this application specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the scope of protection of this application.

Claims

1. A start-up control method for an all-DC combined grid-type energy storage network in isolated grids, characterized in that, Includes the following steps: Monitor whether the grid-type energy storage system is in a dormant state, wherein the grid-type energy storage system includes multiple energy storage units; In a dormant state, each energy storage unit in the grid-type energy storage system sends a distributed negotiation command with its own status information to all other multiple energy storage units, and receives its own status information from all other multiple energy storage units. Each energy storage unit calculates a priority score based on all its own status information and sends the priority score to other energy storage units. In this case, the connection between multiple energy storage units and the DC bus is interrupted. Each energy storage unit selects the corresponding target energy storage unit as the main start-up unit based on all priority scores, and the remaining energy storage units are designated as slave units. The main start-up unit executes an adaptive soft-start algorithm to pre-charge the DC bus connected to the grid-type energy storage system so that the DC bus voltage reaches the rated voltage. Each of the slave units monitors whether the startup status of the main startup unit meets the preset conditions according to preset requirements; If the preset conditions are not met, each slave unit sends a fault-tolerant reselection instruction to all other slave units; Each slave unit reselects a target master boot unit according to the fault-tolerant reselection instruction; If the preset conditions are met, all energy storage units except the main start-up unit will act as slave units and re-establish electrical connections with the DC bus based on their own converters to form voltage regulation, thereby completing the construction of the islanded grid. The steps for monitoring whether a grid-type energy storage system is in a dormant state include: Monitor the DC bus voltage of the grid-type energy storage system, collect the raw voltage data of the DC bus at the connection point between each energy storage unit and the DC bus, and simultaneously collect the frequency fluctuation data of the grid-type energy storage system and the output power change rate of each energy storage unit. Obtain the preset voltage threshold, frequency stability threshold, and power change rate threshold for the grid-type energy storage system; The original voltage data is processed to obtain the filtered voltage value. At the same time, a sliding window variance analysis is performed on the frequency fluctuation data to obtain the frequency stability index. The output power change rate is trend-fitted to obtain the power attenuation slope. The filtered voltage value is compared with the voltage threshold, the frequency stability index is compared with the frequency stability threshold, and the power attenuation slope is compared with the power change rate threshold. Based on the fuzzy logic algorithm, the voltage comparison results, frequency stability comparison results and power attenuation comparison results are fused and calculated to obtain the system silence confidence. If the system's dormancy confidence level exceeds a preset confidence threshold and the duration exceeds a first preset time, then the grid-type energy storage system is determined to have entered a dormant state.

2. The method for starting up an isolated grid of energy storage system with all-DC converged grid structure according to claim 1, characterized in that, The steps for each energy storage unit to calculate its priority score based on all its own state information include: Extract the state of charge, rated capacity, and electrical distance parameters from the system core bus from the self-state information; Identify the current operating modes of the grid-type energy storage system, including the rapid recovery mode, the stable operation mode, and the economical operation mode; Based on the identified operational mode category, modal adaptation and reconstruction are performed on the self-state information, including: In the fast recovery mode, the state of charge value is reconstructed to the maximum supportable power value; Under stable operating conditions, the rated capacity value is reconstructed into a capacity stability coefficient; Under the economic operation mode, the electrical distance parameter is reconstructed into a transmission efficiency factor; Based on the reconstructed self-state information, a multimodal competitive scoring matrix is ​​established, and the modal fit score of each energy storage unit under different operating modes is calculated. Based on the modal fit score of each energy storage unit in the current operating mode, and combined with its relative ranking in other operating modes, the modal competitive advantage value is calculated. Based on the modal competitive advantage value, the final priority score is generated; Each energy storage unit broadcasts the priority score as part of the distributed negotiation instruction to all other energy storage units.

3. The method for starting up an isolated grid of energy storage system with all-DC converged grid structure according to claim 1, characterized in that, The main starting unit executes an adaptive soft-start algorithm to pre-charge the DC bus connected to it so that the DC bus voltage reaches the rated voltage. The steps include: Each energy storage unit compares all priority scores and determines the energy storage unit with the highest priority score as the target energy storage unit. The target energy storage unit is set as the master start-up unit, and the remaining energy storage units are set as slave units. The main starting unit acquires the control parameters of its converter, including the rated voltage, time constant, and maximum allowable current. Based on the control parameters, the main start-up unit executes an adaptive soft-start algorithm to bring the DC bus into a voltage build-up state: The main starting unit controls the voltage output of its converter to the DC bus to start from zero and gradually approach the rated voltage in an exponential growth pattern. During the voltage rise process, the main start-up unit samples the DC bus charging current in real time and limits the current to below the maximum allowable current so that the DC bus voltage reaches the rated voltage. The master startup unit periodically sends heartbeat signals to each slave unit.

4. The method for starting up an isolated grid of energy storage system with all-DC converged grid structure according to claim 1, characterized in that, The steps for each slave unit to monitor whether the startup status of the main startup unit meets preset conditions according to preset requirements include: Each slave unit continuously monitors the DC bus voltage establishment status and determines whether the DC bus voltage reaches the preset stable range of the rated voltage within a second preset time. Each slave unit continuously monitors the heartbeat signal periodically broadcast by the master startup unit and determines whether the slave unit has received a valid signal within a preset number of consecutive times; If the DC bus voltage fails to reach the preset stable range within the second preset time, or if the heartbeat signal is lost for a preset number of consecutive times, it is determined that the preset condition is not met. If the DC bus voltage reaches a stable range within a second preset time and a valid heartbeat signal is received within a preset number of times, then the preset conditions are deemed met.

5. The method for starting up an isolated grid of energy storage system with all-DC converged grid structure according to claim 1, characterized in that, If the preset conditions are not met, each slave unit sends a fault-tolerant reselection instruction to all other slave units. The steps for each slave unit to reselect the target master boot unit according to the fault-tolerant reselection instruction include: If the preset conditions are not met, each slave unit analyzes the triggering factors of the main start-up unit failure, including the characteristics of DC bus voltage build-up failure, heartbeat signal loss mode, and failure occurrence time characteristics. A re-election mode recognition mechanism is established based on the aforementioned triggering factors. A re-election strategy is determined based on the characteristics of pressure failure and the heartbeat signal loss mode. The re-election strategy includes a fast recovery mode and a smooth switching mode. In fast recovery mode, each slave unit calls preset dynamic capability profile data, which is constructed based on the historical startup success rate, voltage support response time and current environmental adaptability of each unit. Based on the dynamic capability profile data, an emergency situation assessment algorithm is used to directly generate the emergency priority score of the candidate unit, thereby skipping the conventional priority score calculation process. In smooth switching mode, each slave unit constructs a cooperative operation matching matrix based on the rated capacity coordination of each unit and the similarity of converter control characteristics, and calculates the cooperative operation efficiency value between units. Based on the identified re-election mode, the corresponding evaluation data is selected. In the rapid recovery mode, the emergency priority score is used, and in the smooth switching mode, the collaborative operation efficiency value is used. Based on the selected evaluation data, a rapid election process is executed to determine the slave unit with the highest emergency priority score or collaborative operation efficiency score in the corresponding mode as the new master startup unit.

6. The method for starting up an isolated grid of energy storage system with all-DC converged grid structure according to claim 1, characterized in that, If the preset conditions are met, all energy storage units except the main start-up unit, acting as slave units, re-establish electrical connections with the DC bus based on their own converters and form voltage regulation. The steps to complete the construction of the islanded grid include: If the preset conditions are met, each slave unit obtains a DC bus voltage stability signal and determines whether the DC bus voltage is maintained within the preset stable range of the rated voltage and exceeds the third preset time. Based on the voltage stabilization signal, each slave unit is sorted according to its priority score, and the input order is determined from high to low. Calculate the specific delayed input time for each unit based on the input order; After each slave unit reaches its corresponding delayed start time, it controls its converter to connect to the DC bus and switches the control mode from standby mode to network construction mode to complete the construction of the isolated network.

7. A start-up control system for islanded energy storage networks with all-DC combined grids, characterized in that, include: A monitoring module is used to monitor whether the grid-type energy storage system is in a dormant state, wherein the grid-type energy storage system includes multiple energy storage units; The calculation module is used to send a distributed negotiation command with its own status information to all other multiple energy storage units when the grid-type energy storage system is in a dormant state, and to receive its own status information from all other multiple energy storage units. Each energy storage unit calculates a priority score based on all its own status information and sends the priority score to other energy storage units. The connection between multiple energy storage units and the DC bus is interrupted. The pressure-building module is used to select the corresponding target energy storage unit as the main start-up unit based on all priority scores, and the remaining energy storage units as slave units. The main start-up unit executes an adaptive soft-start algorithm to pre-charge the DC bus connected to the grid-type energy storage system so that the DC bus voltage reaches the rated voltage. The judgment module is used to enable each slave unit to monitor whether the startup status of the main startup unit meets the preset conditions according to preset requirements; The reselection module is used to send a fault-tolerant reselection command to all other slave units when the preset conditions are not met. Each slave unit reselects a target master boot unit according to the fault-tolerant reselection instruction; The module is used to construct an isolated grid by having all energy storage units except the main start-up unit act as slave units and re-establish electrical connections with the DC bus based on their own converters to form a voltage regulator when preset conditions are met. The steps for monitoring whether a grid-type energy storage system is in a dormant state include: Monitor the DC bus voltage of the grid-type energy storage system, collect the raw voltage data of the DC bus at the connection point between each energy storage unit and the DC bus, and simultaneously collect the frequency fluctuation data of the grid-type energy storage system and the output power change rate of each energy storage unit. Obtain the preset voltage threshold, frequency stability threshold, and power change rate threshold for the grid-type energy storage system; The original voltage data is processed to obtain the filtered voltage value. At the same time, a sliding window variance analysis is performed on the frequency fluctuation data to obtain the frequency stability index. The output power change rate is trend-fitted to obtain the power attenuation slope. The filtered voltage value is compared with the voltage threshold, the frequency stability index is compared with the frequency stability threshold, and the power attenuation slope is compared with the power change rate threshold. Based on the fuzzy logic algorithm, the voltage comparison results, frequency stability comparison results and power attenuation comparison results are fused and calculated to obtain the system silence confidence. If the system's dormancy confidence level exceeds a preset confidence threshold and the duration exceeds a first preset time, then the grid-type energy storage system is determined to have entered a dormant state.

8. A computer device comprising a memory and a processor, wherein the memory stores a computer program, characterized in that, When the processor executes the computer program, it implements the steps of the method according to any one of claims 1 to 6.

9. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by a processor, it implements the steps of the method according to any one of claims 1 to 6.

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