Optical storage parallel network control method

Abstract

The invention provides an optical storage parallel network control method, which comprises the following steps: calculating the current load rate percentage of each residual unit according to the connection relation and electrical path information of the residual units after isolation; evaluating the available margin capacity and the frequency regulation bearing capacity of the remaining units, matching the available margin capacity and the frequency regulation bearing capacity with a specific power value and a frequency regulation requirement which need to be compensated, and determining a feasible unit combination scheme for fault recovery; generating a power redistribution list and a frequency adjustment responsibility distribution table according to the direct current bus connection mode of the optimal unit recombination, and obtaining an output power set value and a frequency adjustment parameter of each unit after adjustment; and extracting the continuous power supply time value of the optical storage parallel network, updating the total power supply capacity value of the optical storage parallel network, and maintaining the continuous power output and frequency stability after the fault of the optical storage parallel network.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of information technology, and in particular to a light storage parallel network control method. BACKGROUND

[0002] In the field of energy management and power systems, the research of light storage parallel network is of great significance. This field is directly related to the efficient use of new energy and the stable operation of the power grid, and is the core pillar of promoting energy transformation and ensuring the safety of power supply. Especially in distributed energy systems, light storage parallel network integrates photovoltaic power generation and energy storage devices to provide continuous and stable power support for users, which is self-evident. However, the current light storage parallel network has the problem of not being flexible enough in coping with sudden conditions. Many existing methods often have difficulty in quickly adapting to changes in network state when facing device failures, resulting in a decline in the overall operating efficiency of the system. The deeper problem is that after a fault occurs, the coordination between the various parts of the network is insufficient, which can easily lead to uneven resource allocation and further exacerbate the instability of the system. This limitation makes the system appear to be inadequate in the face of complex operating environments. Focusing on technical difficulties, a key challenge in light storage parallel networks is the dynamic balancing of power gaps. A power gap refers to the decline in the overall output capacity of the network when a certain energy storage device is disconnected due to a fault, and this decline needs to be compensated by other devices. However, due to the limited carrying capacity of each device, this compensation process often leads to a sudden increase in the load of other devices, even exceeding their safe operating range. Further, this contradiction between power gaps and the carrying capacity of remaining devices is not isolated, but is influenced by the scale of the fault and the complexity of the network structure, forming a chain reaction. For example, in a parallel network composed of multiple energy storage devices, if a device suddenly disconnects, the power demand it originally carried will immediately be transferred to other devices, and if the remaining devices do not have enough carrying capacity to support this additional load, an overload risk will be triggered, and even more devices will fail due to excessive load. In addition, the remaining energy storage units need to bear greater frequency regulation responsibilities, but their control bandwidth and response speed differences will lead to frequency domain coupling oscillation. Therefore, how to quickly identify the size of the power gap after a fault occurs and reasonably assess the carrying capacity of the remaining devices to avoid the risk of chain overload has become a key problem for the stable operation of light storage parallel networks. SUMMARY

[0003] The present application provides a light storage parallel network control method, mainly comprising:

[0004] The operating state signals of each energy storage unit in the optical storage parallel network are acquired, the fault isolation object is determined, the connection relationship and electrical path information of the remaining units after isolation are acquired, the current load rate of each remaining unit is calculated according to the connection relationship and electrical path information of the remaining units after isolation, the real-time output power value of the isolated unit and the frequency regulation responsibility borne by the isolated unit are acquired, the specific power value to be compensated and the frequency regulation responsibility distribution amount are determined in combination with the current load rate, the available residual capacity and the frequency regulation bearing capacity of the remaining units are evaluated, and the specific power value to be compensated and the frequency regulation requirement are matched to determine a feasible unit combination scheme for fault recovery, the load increase amplitude of each DC bus connection path in the feasible unit combination scheme is evaluated, the connection path causing the minimum battery temperature rise and the lowest frequency domain coupling risk is identified, and the optimal DC bus connection mode of the unit recombination is obtained, the power redistribution list and the frequency regulation responsibility distribution table are generated according to the optimal DC bus connection mode of the unit recombination, and the output power set value and the frequency regulation parameter of each unit after adjustment are obtained, the output power set value and the frequency regulation parameter of each unit after adjustment are issued to the remaining units, and when the current load rate of any remaining unit exceeds the upper limit value of the battery safe discharge rate or the frequency domain oscillation sign is detected, the power redistribution process and the frequency response coordination are triggered to obtain the stable output power set value and the frequency regulation strategy of each unit, and the continuous power supply time value of the optical storage parallel network is extracted to update the overall power supply capacity value of the optical storage parallel network.

[0005] Further, the operating state signals of each energy storage unit in the optical storage parallel network are acquired, the fault isolation object is determined, the connection relationship and electrical path information of the remaining units after isolation are acquired, including:

[0006] The voltage and current data of each energy storage unit are acquired from the data acquisition terminal of the optical storage parallel network, the deviation of the output voltage of the energy storage unit from the standard voltage threshold value is compared, the energy storage unit with abnormal output is identified, the fault unit number and the fault type code are determined according to the communication state and the power output mark of the energy storage unit with abnormal output, the off-line or overloaded energy storage unit is marked as the fault isolation object according to the matching of the fault type code and the preset fault type table, the upstream and downstream connection nodes of the fault isolation object in the network are read, and the electrical connection topological structure of the remaining energy storage units is acquired, the network frequency data within a preset time window before and after the fault is collected, the mean difference value of the frequency data is calculated to obtain the frequency offset, the adjustment power change of each remaining energy storage unit is recorded, and the connection relationship and electrical path information of the remaining units after isolation are determined.

[0007] Further, the current load rate of each remaining unit is calculated according to the connection relationship and electrical path information of the remaining units after isolation, including:

[0008] Obtain the real-time output power and the maximum carrying capacity of each remaining energy storage unit, query the frequency response bandwidth range and the adjustment speed parameter of the remaining energy storage unit, calculate the real-time output power divided by the maximum carrying capacity, and obtain the current load rate of each remaining energy storage unit.

[0009] Further, obtain the real-time output power value of the isolation unit and the frequency regulation responsibility it bears, and determine the specific power value to be compensated and the frequency regulation responsibility allocation amount in combination with the current load, including:

[0010] Obtain the real-time output power and the frequency regulation responsibility of the isolation unit before the fault, calculate the proportion of the output power of the isolation unit to the total demand power of the network to obtain power weight data, determine the real-time output power as a power gap according to the power weight data, extract the regulation power value in the frequency regulation responsibility, and determine the frequency regulation gap; in combination with the current load rate, calculate the difference sum of the maximum carrying capacity and the real-time output power of each remaining energy storage unit to determine the specific power value to be compensated and the frequency regulation responsibility allocation amount.

[0011] Further, evaluate the available residual capacity and frequency regulation carrying capacity of the remaining units and match them with the specific power value to be compensated and the frequency regulation demand to determine a feasible unit combination scheme for fault recovery, including:

[0012] Calculate the difference between the maximum carrying capacity and the current output power of the remaining energy storage unit to obtain the available residual capacity; read the upper and lower limits of the frequency response bandwidth of the remaining energy storage unit, calculate the bandwidth range occupied by the current frequency offset, determine the frequency response bandwidth residual, read the control parameter configuration of the remaining energy storage unit, compare the parameter difference degree, mark the unit pair with frequency domain coupling risk, exclude the unit pair with frequency domain coupling risk, select the combination with the shortest electrical connection path, accumulate the residual available power of each unit in the combination, compare it with the compensated power value, verify whether the total frequency regulation capacity meets the frequency regulation demand, and determine the unit combination scheme for fault recovery.

[0013] Further, evaluate the load increase amplitude of each DC bus connection path in the feasible unit combination scheme, identify the connection path that causes the minimum unit cell temperature rise and the lowest frequency domain coupling risk, and obtain the optimal DC bus connection mode of the recombined units, including:

[0014] The current load current and rated carrying capacity of the DC bus connection path in the reading unit combination scheme are combined, the ratio of the current increase to the rated carrying capacity is calculated, the load increase amplitude is obtained, the real-time temperature and historical temperature rise rate of the remaining energy storage unit are read, the difference between the expected temperature rise value and the upper limit of the safety temperature is calculated, the temperature rise risk level is determined, the frequency response phase difference and amplitude ratio of the remaining energy storage unit are extracted, the phase margin is judged, the frequency domain coupling risk is evaluated, and the path with low temperature rise risk level and frequency domain coupling risk meeting the requirements is marked as a candidate optimization path; the residual capacity of the remaining energy storage unit in the candidate optimization path is divided by the discharge current to obtain the residual discharge time, the weight is set according to the residual discharge time, and the optimal DC bus connection mode is determined.

[0015] Further, according to the optimal unit recombination DC bus connection mode, a power redistribution list and a frequency adjustment responsibility allocation table are generated, the output power set value and the frequency adjustment parameter of each unit after adjustment are obtained, including:

[0016] The residual available power and the battery residual discharge time of the remaining energy storage unit in the optimal DC bus connection mode are read, the residual discharge time proportion is calculated, and the distribution weight coefficient is obtained; the compensated power value is distributed according to the distribution weight coefficient to form a power distribution list; the frequency response bandwidth overlap range and the adjustment speed difference of the remaining energy storage unit are compared, the frequency adjustment responsibility amount is allocated, and a frequency adjustment responsibility allocation table is generated; according to the power distribution list and the frequency adjustment responsibility allocation table, the output power set value of each unit after adjustment is calculated, and the frequency adjustment responsibility amount is mapped to a frequency adjustment parameter.

[0017] Further, the output power set value and the frequency adjustment parameter of each unit after adjustment are issued to the remaining units, and when any remaining unit current load rate exceeds the upper limit of the battery safe discharge rate or the frequency domain oscillation sign is detected, the power redistribution process and the frequency response coordination are triggered to obtain the stable output power and the frequency adjustment strategy of each unit, including:

[0018] The output power set value and the frequency adjustment parameter are issued to the remaining energy storage unit, the DC voltage, the output current and the frequency deviation value are collected, the ratio of the output current to the rated current is calculated, and the current load rate is obtained; the time domain waveform of the current load rate is analyzed, the power fluctuation periodicity and amplitude are identified, and the frequency domain oscillation sign is judged; if any remaining unit current load rate exceeds the upper limit of the battery safe discharge rate or the frequency domain oscillation sign is abnormal, the power distribution value and the frequency response parameter are recalculated, the output power is adjusted, the frequency deviation is monitored, and the stable output power set value and the frequency adjustment strategy are determined.

[0019] Further, the continuous power supply time value of the photovoltaic storage parallel network is extracted, and the total power supply capacity value of the photovoltaic storage parallel network is updated, including:

[0020] The power values ​​and remaining battery capacity of each energy storage unit are read, and the remaining capacity is calculated by dividing the power value to obtain the minimum power supply duration as the continuous power supply time. The instantaneous power output of the energy storage converter and the DC bus voltage are collected and accumulated to obtain the real-time total power of the network. The frequency deviation value of the real-time total power of the network is read, and the ratio of the difference between the frequency deviation value and the stability threshold is calculated to obtain the system frequency stability margin. Based on the real-time total power of the network and the system frequency stability margin, the overall power supply capacity value of the photovoltaic-storage parallel network is updated.

[0021] The technical solutions provided by the embodiments of the present invention may include the following beneficial effects:

[0022] This invention discloses a control method for a photovoltaic-storage parallel network. Addressing the power shortage and frequency instability caused by energy storage unit failures, it achieves continuous power supply and frequency stability through a closed-loop mechanism involving fault detection, isolation, power and frequency regulation parameter reallocation, and real-time monitoring. First, by extracting the faulty unit number and type, offline or overloaded units are accurately isolated. Frequency response characteristics before and after the fault are analyzed, and power and frequency regulation gaps are calculated. Based on the load factor, frequency response bandwidth, and regulation speed of the remaining units, available margin and compensation requirements are matched. The DC bus connection path with the lowest frequency domain coupling risk is selected, and combined with battery temperature and remaining discharge time weights, an optimal power allocation list and frequency regulation strategy are generated. This invention ensures the safe operation of each unit by dynamically triggering reallocation through real-time monitoring of load factor and frequency stability. Ultimately, it achieves network power supply capacity updates and frequency stability after a fault, significantly improving the fault tolerance and operational reliability of the photovoltaic-storage parallel network. Attached Figure Description

[0023] Figure 1 This is a flowchart of a parallel network control method for optical storage according to the present invention. Detailed Implementation

[0024] The technical solutions of the embodiments of the present invention will be clearly and thoroughly described below with reference to the accompanying drawings. The described embodiments are merely some embodiments of the present invention.

[0025] like Figure 1 This embodiment of a photovoltaic-storage parallel network control method may specifically include:

[0026] Step S101: Obtain the operating status signal of each energy storage unit in the photovoltaic-energy storage parallel network, determine the fault isolation object, and at the same time monitor the changes in network frequency response characteristics to obtain the connection relationship and electrical path information of the remaining units after isolation.

[0027] Real-time voltage and current values of each energy storage unit are obtained from a data acquisition terminal of the optical storage parallel network, and the output abnormal energy storage unit is identified by comparing the deviation of the output voltage of each energy storage unit from the standard voltage threshold. According to the communication state identifier and power output marker of the output abnormal energy storage unit, the corresponding fault unit number and fault type code are extracted. According to the matching result of the fault type code and the preset fault type comparison table, if the fault type code value is 01 corresponding to the offline state of the energy storage unit or the code value is 02 corresponding to the overload state of the energy storage unit, the energy storage unit is marked as a fault isolation object, and the electrical connection topology structure between the remaining energy storage units after fault isolation is obtained by reading the upstream and downstream connection node information of the fault isolation object in the optical storage parallel network. Network frequency sampling data within a preset time window before and after the fault occurs is collected, and the frequency offset is obtained by calculating the difference between the frequency mean values before and after the fault. By comparing the adjustment power output value changes of each energy storage unit before and after the fault, the frequency regulation capacity value of each remaining energy storage unit is recorded, and the connection relationship and electrical path information of the remaining units after isolation are determined according to the electrical connection topology structure and the frequency regulation capacity value.

[0028] Specifically, in one embodiment, the optical storage parallel network monitors the operating parameters of each energy storage unit in real time through a distributed data acquisition terminal. Each data acquisition terminal obtains the DC bus voltage and output current values of the corresponding energy storage unit at a sampling rate of 100 Hz. When the output voltage of a certain energy storage unit deviates from the rated value by more than 5%, the monitoring program marks this unit as an output abnormal unit. By reading the communication state register in the energy storage management system, it is determined whether the unit is in an offline state, and the power output marker bit is checked to confirm whether there is an overload condition.

[0029] For example, when the fault type code of the No. 3 energy storage unit is detected as 01, it indicates that the unit is offline due to communication interruption, and it needs to be isolated from the parallel network. The isolation process is achieved by disconnecting the DC contactor of the unit, and the network topology structure data is updated at the same time. The network topology structure includes the electrical connection relationship between each energy storage unit, the bus node distribution, and the power flow information.

[0030] Preferably, the connection matrix of the remaining energy storage units is reconstructed by traversing the adjacent node list of the fault unit, which records whether there is a direct electrical connection between each two units and the impedance parameter of the connection path. The monitoring of the frequency response characteristic involves real-time tracking of the frequency fluctuation on the AC side of the network. Five seconds of frequency data are collected before and after the fault occurs, and the frequency deviation value is calculated based on 50 Hz. By comparing the difference between the frequency mean values before and after the fault, the influence of the fault on the frequency stability of the system can be quantitatively evaluated.

[0031] For example, when a certain energy storage unit assumes 2MW of frequency regulation power, its sudden offline will cause the system frequency to drop by about 0.2Hz. At this time, the change in the regulation power of each remaining energy storage unit before and after the fault needs to be recorded, which directly reflects the distribution of the frequency regulation capacity of each unit.

[0032] In one possible implementation, the acquisition of electrical path information is based on a pre-established network impedance model. The model stores the resistance and inductance parameters of each bus segment in the path information table, and when fault isolation is completed, the equivalent impedance value of each path is calculated by traversing all reachable paths between the remaining units through a depth-first search algorithm. The smaller the path impedance value, the higher the power transmission efficiency, so low-impedance paths will be preferentially selected when power is redistributed.

[0033] Step S102, according to the connection relationship of the remaining units after isolation and the electrical path information, the current load rate percentage of each remaining unit is calculated.

[0034] According to the connection relationship of the remaining units after isolation, the real-time output power value and the rated maximum carrying capacity of each remaining energy storage unit are read from the data bus of the optical storage parallel network, and the frequency response bandwidth range value and the power regulation speed parameter stored in the unit controller are queried to obtain the operating state data of each remaining unit. For the power information of each energy storage unit in the operating state data, the current load rate percentage of each remaining unit is calculated by dividing the current output power value by the rated maximum carrying capacity value and multiplying by one hundred.

[0035] Specifically, in one embodiment, the data bus of the optical storage parallel network uses the Modbus communication protocol, and the operating parameters of each energy storage unit are polled every 500 milliseconds. The real-time output power value is obtained by reading the power register of the energy storage converter, and the rated maximum carrying capacity is extracted from the configuration file of the energy storage battery management system. The frequency response bandwidth represents the response range of the energy storage unit to the frequency change of the power grid, and is usually set to 49.5Hz to 50.5Hz. The power regulation speed parameter reflects the change rate of the output power of the energy storage unit, with a unit of MW / s. These two parameters together determine the ability of the energy storage unit to participate in frequency regulation.

[0036] For example, the frequency response bandwidth of a certain energy storage unit is 1Hz, and the power regulation speed is 2MW / s, indicating that the unit can adjust the output power at a rate of 2MW per second within a frequency deviation range of 1Hz.

[0037] Specifically, the calculation of the load percentage is completed by real-time monitoring. When the current output power of a certain energy storage unit is 800 kW and the rated maximum carrying capacity is 1000 kW, the load percentage of the energy storage unit is 80%. This value directly reflects the operating margin of the energy storage unit and provides a quantitative basis for subsequent power redistribution.

[0038] In step S103, the real-time output power value of the isolated unit and the amount of frequency regulation responsibility it assumes are obtained, and combined with the current load percentage, the power gap value and the frequency regulation gap value after the failure unit is shut down are calculated, and the specific power value to be compensated and the frequency regulation responsibility distribution amount are determined.

[0039] The real-time output power value of the isolated unit before the failure occurs and the amount of frequency regulation responsibility assumed by the unit are obtained, the total power output of all energy storage units in the optical storage parallel network is read as the total demand power of the network, the proportion of the output power of the isolated unit to the total demand power is calculated, and the power weight data of the isolated unit is obtained. According to the power weight data and the real-time output power value of the isolated unit, the output power value of the isolated unit is directly used as the power gap value after the failure unit is shut down, and the regulation power value assumed by the isolated unit is extracted from the frequency regulation responsibility amount to determine the frequency regulation gap value. Combined with the current load percentage of each remaining unit, the difference between the maximum carrying capacity and the current output power of each remaining unit is calculated, and the power gap value is compared with the difference sum. If the power gap exceeds the preset proportion threshold of the difference sum, the power distribution weight is adjusted, and according to the frequency regulation gap value and the power gap value, the specific power value to be compensated and the frequency regulation responsibility distribution amount are determined.

[0040] Specifically, in one embodiment, the optical storage parallel network evaluates the impact of the failure by real-time monitoring of the operating data of each energy storage unit. When a certain energy storage unit is isolated, the output power value of the unit in the last sampling period before the failure is immediately read, and this value represents the lost power supply capability of the network. At the same time, the amount of frequency regulation responsibility assumed by the isolated unit is extracted from the frequency control, which is in units of MW / Hz and represents the response capability of the unit to frequency deviation. The calculation of the power weight data is based on the power distribution of the entire network.

[0041] Specifically, the total demand power of the network is obtained by accumulating the real-time output power of all energy storage units, and then the percentage of the isolated unit power to the total power is calculated.

[0042] For example, if the isolated unit outputs 2MW and the total power of the network is 10MW, the power weight of this unit is 20%. This weight value directly reflects the importance of the unit in the entire network. The determination of the power gap uses a direct assignment method, that is, the output power value of the isolated unit is taken as the power gap that needs to be compensated. The frequency regulation gap is obtained by analyzing the historical regulation records of the isolated unit, including the actual regulation power output of the unit under different frequency deviations.

[0043] In one possible implementation, a frequency regulation responsibility allocation table is maintained to record the reference regulation power and dynamic regulation range assumed by each energy storage unit. When a unit is isolated, its corresponding regulation responsibility becomes the frequency regulation gap, which needs to be redistributed among the remaining units. The evaluation of compensation capacity involves the calculation of the available capacity of the remaining units. By subtracting the current output power from the maximum carrying capacity of each remaining unit, the available compensation capacity of the unit is obtained. The available compensation capacities of all remaining units are accumulated to obtain the total compensation capacity of the system. If the power gap exceeds 80% of the total compensation capacity, it is determined to be a high-risk state, at which time the power allocation weight needs to be adjusted to prioritize the power supply of critical loads. Further, the adjustment of the power allocation weight is based on the comprehensive consideration of multiple factors. In addition to the available capacity of each unit, the response speed, regulation accuracy and current operating efficiency of the unit also need to be evaluated. By establishing a weight adjustment matrix, the compensation proportion assumed by each unit is dynamically adjusted according to different operating scenarios to realize the reasonable allocation of the power gap.

[0044] Step S104, the available residual capacity and frequency regulation carrying capacity of the remaining units are evaluated and matched with the specific power value that needs to be compensated and the frequency regulation demand to determine the feasible unit combination scheme for fault recovery.

[0045] The maximum carrying capacity and current output power value of each remaining energy storage unit are obtained, the available residual capacity of each unit is obtained by calculating the difference between the maximum carrying capacity and the current output power, the upper and lower limit values of the frequency response bandwidth of each unit are read from the frequency controller, the remaining frequency response bandwidth is calculated according to the bandwidth range occupied by the current frequency offset, and the residual available power value and the bearable frequency adjustment capability data of each unit are determined. According to the bearable frequency adjustment capability data and the frequency response characteristics of each unit, the control parameter configuration inside the energy storage converter is read, including the regulator gain value and the response time constant, the parameter difference between different units is compared, if the difference exceeds the preset stability margin threshold, the unit pair with the risk of frequency domain coupling is marked, and the frequency domain coupling risk assessment result is obtained. Based on the frequency domain coupling risk assessment result, the unit pair combination with coupling risk is excluded, the combination with the shortest electrical connection path is selected from the remaining risk-free units, and the residual available power value of each unit in the combination is accumulated and compared with the specific power value that needs to be compensated to obtain the candidate unit set that meets the power compensation demand. For the candidate unit set, it is verified whether the sum of the frequency adjustment capabilities is greater than the frequency adjustment demand value, if it is satisfied and the sum of all residual available power values is greater than the power value that needs to be compensated, then according to the matching degree of the physical connection distance and the control response time between the units, the feasible unit combination scheme for fault recovery is determined.

[0046] Specifically, in an embodiment, the capacity evaluation of the optical energy storage parallel network starts from the real-time operation data of each energy storage unit. Each energy storage unit is equipped with an independent battery management system, which monitors the charge and discharge state, temperature distribution and health state of the battery pack in real time. The maximum carrying capacity is determined comprehensively according to the rated capacity of the battery, the current state of charge and the temperature correction coefficient.

[0047] For example, a certain energy storage unit has a rated capacity of 1000 kWh, a current state of charge of 80%, and a temperature correction coefficient of 0.95. Its actual maximum carrying capacity is 760 kWh. By subtracting the current output power, the available residual capacity of the unit is obtained. The calculation of the frequency response bandwidth margin involves in-depth analysis of the control characteristics of the energy storage converter. The frequency response bandwidth is defined as the range of frequency deviation that the energy storage unit can respond to, usually within a range of 0.5 Hz above and below the system rated frequency. The occupied bandwidth by the current frequency deviation is obtained by real-time frequency measurement. If the system frequency deviates from the rated value by 0.2 Hz, the occupied bandwidth is 0.2 Hz, and the remaining available bandwidth is 0.3 Hz. This margin determines the ability space of the unit to continue participating in frequency regulation. The control parameters of the energy storage converter include PID parameters such as proportional gain, integral time constant, and derivative coefficient, as well as the bandwidth settings of the current loop and voltage loop. Different manufacturers or batches of energy storage equipment may have different control parameter settings, which may cause mutual interference between control loops when operating in parallel. By reading the parameter configuration file of each unit converter, the key control parameters are extracted. The regulator gain value reflects the amplification degree of the controller to the deviation signal, and the response time constant determines the speed of the system to reach steady state. When the response time constants of two units differ by more than 50%, the fast-response unit may have over-regulated before the slow-response unit has fully responded, leading to system oscillation. The parameter difference degree is obtained by calculating the relative deviation of each parameter and weighted sum, and the weight is determined according to the influence of the parameter on the stability of the system. The determination of frequency domain coupling risk adopts the stability margin analysis method. The stability margin threshold is usually set to a phase margin of 45 degrees and an amplitude margin of 6 dB, which is the basic requirement to ensure stable operation of the system. When the control parameters of two units differ, causing the stability margin of the combined system to be lower than the threshold, the units are marked as having coupling risk. In practical applications, the electrical distance between units also needs to be considered. The closer the distance, the more obvious the coupling effect.

[0048] In one possible implementation, the selection of the candidate unit set adopts a combinatorial optimization method. First, all unit pairs with coupling risk are excluded to avoid their simultaneous participation in power compensation. Then, the electrical connection paths of the remaining units are evaluated, and the path length is measured by the number of bus segments and switch nodes. The shorter the path, the smaller the power transmission loss and the faster the response speed. A connection matrix is constructed to record the electrical distance between units, and the shortest path algorithm is used to find the most closely connected unit combination.

[0049] Exemplarily, the matching process of power compensation demand needs to consider both power balance and frequency stability. The remaining available power of each unit in the candidate unit set is accumulated and compared with the power gap that needs to be compensated. At the same time, it is evaluated whether the sum of the frequency adjustment capabilities of these units meets the frequency adjustment demand of the system. The frequency adjustment demand includes not only static frequency deviation compensation, but also dynamic frequency change rate suppression. Further, the physical connection distance affects the power transmission efficiency and response delay. The farther the physical distance between two units, the greater the impedance of the connecting cable and the higher the power transmission loss. The matching degree of the control response time determines the effect of multiple units working together. Units with similar response times can act synchronously and avoid mutual interference. The determination of the feasible unit combination scheme is a multi-objective optimization process. In addition to meeting the power and frequency adjustment demand, the economy and reliability of system operation also need to be considered. By establishing comprehensive evaluation indexes, including power matching degree, frequency adjustment capability matching degree, coupling risk level, transmission loss, etc., different combination schemes are quantitatively scored.

[0050] For example, in a photovoltaic storage parallel network containing 8 energy storage units, when unit 2 is isolated after failure, the system needs to select a suitable combination from the remaining 7 units to compensate for a power gap of 2 MW. Through evaluation, it is found that units 3 and 5 have frequency domain coupling risk, and unit 4 has a current load rate of 85%, with limited available capacity. Units 1, 6 and 7 are selected to form the compensation combination, their control parameters are similar, the electrical connection path is short, and the total available power is 2.5 MW, meeting the compensation demand and leaving a certain margin.

[0051] Step S105, evaluate the load increase amplitude of each DC bus connection path in the feasible unit combination scheme, identify the connection path that causes the smallest unit battery temperature rise and the lowest frequency domain coupling risk, and obtain the optimal DC bus connection mode of unit recombination.

[0052] For each DC bus connection path in the feasible unit combination scheme, the current load current value and the rated carrying capacity of each node on the path are read, the current increase caused by power redistribution after failure is calculated, and the load increase percentage of each path is obtained by the ratio of the current increase to the rated carrying capacity. According to the load increase percentage, the real-time temperature data and the historical temperature rise rate of each energy storage unit are read from the battery management unit, the expected temperature rise value under different load conditions is calculated by adding the current temperature to the load increase percentage multiplied by the temperature rise rate coefficient, and the difference between the expected temperature rise value and the upper limit of the battery safety temperature is obtained. Temperature rise risk level of each path. Based on the temperature rise risk level, the frequency response phase difference and amplitude ratio parameters of each unit controller are extracted, and the frequency domain coupling risk of different path combinations is evaluated by judging whether the phase margin is greater than the preset stability threshold. If the temperature rise risk level is lower than the preset upper limit and the frequency domain coupling risk meets the stability requirement, the path is marked as a candidate optimization path. The current state of charge percentage and real-time discharge current of each remaining unit in the candidate optimization path are obtained, the remaining discharge time of each unit is calculated by dividing the remaining capacity corresponding to the state of charge by the discharge current, the path selection weight value is set according to the remaining discharge time, and the optimal unit recombination DC bus connection mode is determined by weighted scoring and sorting.

[0053] Specifically, in an embodiment, the evaluation of the DC bus connection path starts from load analysis. The DC bus in the photovoltaic energy storage parallel network undertakes an important task of power transmission, and each bus has its rated carrying capacity limit. When the failed unit is isolated, the power originally borne by the unit needs to be redistributed through other paths, which inevitably leads to an increase in the load of some buses. By real-time monitoring, the current sensor data of each node is obtained, and the instantaneous value and effective value of the current load current are read. The rated carrying capacity is determined according to the material, cross-sectional area and heat dissipation condition of the bus. The carrying capacity of a copper bus is usually higher than that of an aluminum bus. The calculation of the load increase amplitude needs to consider the actual path of power redistribution. When a certain path bears additional power, the current increase is equal to the redistributed power divided by the bus voltage.

[0054] For example, if an additional 500 kW power needs to be transmitted through a certain path, and the DC bus voltage is 750 V, the current increase is about 667 A. Comparing this increase with the rated current of the path, if the rated current is 2000 A and the current load is 1200 A, the percentage of load increase is 33.35%. This percentage directly reflects the load pressure of the path. The energy storage battery generates heat during charging and discharging, and the heat is proportional to the square of the current. The temperature rise rate coefficient characterizes the temperature rise speed caused by unit load increase, and the coefficient is obtained by fitting historical operation data. The battery management unit continuously records the temperature change curve under different load conditions, and extracts the temperature rise rate through data analysis. When the load increases by 30%, if the historical data shows that the temperature rise rate is 0.5°C / min, the expected temperature rise value is the load increase multiplied by the temperature rise rate coefficient and the expected running time. The upper limit of the safety temperature of the battery is usually set to 45°C, the current temperature is 35°C, and the expected temperature rise is 5°C, so the temperature rise risk level is quantified by the remaining temperature margin. The smaller the temperature margin, the higher the risk level. This evaluation method fully considers the thermal safety boundary of the battery. The evaluation of frequency domain coupling risk is based on stability analysis in control theory. The control system of the energy storage converter contains multiple control loops, such as the current inner loop, the voltage outer loop, and the power loop. Each control loop has its characteristic frequency and phase characteristics. When multiple units are operated in parallel, the controllers of different units may interact at certain frequency points. The frequency response phase difference reflects the difference in response time of different units to the same disturbance signal, and the amplitude ratio represents the difference in response strength. The phase margin is an important indicator of system stability, representing the safety distance of the system from the unstable boundary. When the phase of the open-loop transfer function is -180 degrees, the reciprocal of the amplitude at this frequency point is the amplitude margin. In engineering practice, the phase margin is usually required to be greater than 45 degrees, and the amplitude margin is greater than 6 dB, so that the system can remain stable under parameter changes and external disturbances.

[0055] In one possible implementation, the screening of candidate optimization paths adopts a multi-stage evaluation method. First, according to the temperature rise risk level, paths with a risk level exceeding a preset upper limit are excluded. Then, the frequency domain coupling risk is evaluated, and combinations that may produce oscillations are identified by analyzing the matching degree of the control parameters of each unit. Only paths that meet both the temperature rise and stability requirements can become candidate paths.

[0056] Exemplarily, the calculation of the remaining discharge time needs to comprehensively consider the state of charge and the discharge characteristics of the battery. The state of charge is expressed in percentage, reflecting the proportion of the current remaining capacity to the total capacity. The battery capacity of a certain energy storage unit is 1000 kWh, and the current state of charge is 60%, i.e. the remaining capacity is 600 kWh. The real-time discharge current is 400 A, and the bus voltage is 750 V, so the discharge power is 300 kW. The remaining discharge time is equal to the remaining capacity divided by the discharge power, i.e. 2 hours. This time directly affects the ability of the unit to continuously participate in power compensation. Further, the setting of the path selection weight reflects the consideration of the continuous operation ability of the system. The unit with a long remaining discharge time should undertake more compensation tasks to prolong the operation time of the entire system. The weight value is proportional to the remaining discharge time, and a linear or exponential function can be used for mapping.

[0057] For example, the weight of the unit with a remaining time of 3 hours is set to 0.3, and the weight of the unit with a remaining time of 5 hours is set to 0.5.

[0058] It can be understood that the process of weighted scoring integrates multiple evaluation dimensions. In addition to the remaining discharge time, factors such as transmission efficiency of the path and reliability of switch action can also be considered. By establishing a comprehensive scoring function, the evaluation values of each dimension are weighted and summed to obtain the total score of each candidate path.

[0059] For example, in an actual optical storage parallel network, there are three candidate paths to choose from. Path A passes through 2 switch nodes, and the related energy storage unit has a remaining discharge time of 4 hours, a low temperature rise risk level, and a frequency domain coupling risk that meets the requirements, with a comprehensive score of 85. Path B passes through 3 switch nodes, with a remaining discharge time of 3.5 hours and a medium temperature rise risk level, with a score of 75. Path C passes through only 1 switch node, but the related unit has a remaining discharge time of only 2 hours, with a score of 65. According to the score ranking, path A is selected as the optimal DC bus connection mode, achieving the goal of prolonging the system operation time under the premise of ensuring safety.

[0060] Step S106, generating a power redistribution list and a frequency regulation responsibility allocation table according to the DC bus connection mode of the recombined optimal unit, to obtain the output power set value and the frequency regulation parameter of the adjusted unit.

[0061] According to the optimal unit recombination DC bus connection mode, the residual available power value and the battery residual discharge time of each energy storage unit in the connection mode are read, the distribution weight coefficient of each unit is calculated by dividing the residual discharge time of each unit by the total sum of the discharge times of all participating units, the specific power value that needs to be compensated is multiplied by the distribution weight coefficient to obtain the power share that each unit should bear, and a power redistribution list is formed. Based on the power redistribution list, the frequency response bandwidth and the adjustment speed parameter of each energy storage unit are obtained, the overlap range of the frequency response bandwidth and the difference degree of the adjustment speed of different units are compared, the energy storage units with a parameter difference less than a preset threshold are identified, and for the energy storage units, the frequency adjustment responsibility is allocated according to the proportion of the available adjustment capacity to the total adjustment capacity, and a frequency adjustment responsibility allocation table is obtained. According to the power redistribution list and the frequency adjustment responsibility allocation table, the current output power of each unit is added to the allocated power share to obtain the adjusted output power set value of each unit, and the adjustment responsibility of each unit is extracted from the frequency adjustment responsibility allocation table. The adjustment responsibility is mapped to the frequency and power adjustment slope value according to a preset conversion rule to determine the adjusted frequency adjustment parameter.

[0062] Specifically, in an embodiment, the formation of the power redistribution list is based on the time weighting principle. The residual discharge time of each energy storage unit in the optical storage parallel network directly affects its continuous power supply capability. By reading the state of charge data and the current discharge rate of the battery management system, the residual discharge time of each unit is calculated.

[0063] For example, if the residual capacity of a unit is 500 kWh and the current discharge power is 200 kW, the residual discharge time is 2.5 hours. When the residual discharge times of three units are 2.5, 3.0 and 4.5 hours respectively, the total is 10 hours, and the distribution weight coefficients of the units are 0.25, 0.30 and 0.45 respectively. The application of the distribution weight coefficient ensures the rationality of power distribution. If the total power that needs to be compensated is 1000 kW, according to the above weight coefficients, the three units bear 250 kW, 300 kW and 450 kW respectively. This distribution mode makes the units with longer residual discharge time bear more load, prolonging the operation time of the entire system. The power redistribution list records the original power, allocated power and target power value of each unit in detail.

[0064] Specifically, the matching of the frequency response characteristics is realized by parameter comparison. The frequency response bandwidth represents the frequency deviation range that the energy storage unit can respond to, which is usually 49.5 Hz to 50.5 Hz. The adjustment speed parameter reflects the speed of the unit's response to frequency changes, with a unit of MW / Hz. When the frequency response bandwidth of two units overlaps more than 80% and the adjustment speed difference is less than 20%, it is considered that the frequency response characteristics of the two units are similar.

[0065] For example, the response bandwidth of unit A is 49.6-50.4 Hz, the response bandwidth of unit B is 49.5-50.5 Hz, the overlapping range is 0.8 Hz, and the proportion is 80%, which meets the matching condition. The frequency regulation responsibility allocation table is determined according to the available regulation capacity of each unit. The available regulation capacity is equal to the maximum regulation power minus the current regulation power. If the available regulation capacities of the three matching units are 100 MW, 150 MW and 250 MW respectively, the total is 500 MW, and their regulation responsibility proportions are 20%, 30% and 50% respectively. When the total regulation amount required is 200 MW, each unit bears the regulation responsibility of 40 MW, 60 MW and 100 MW respectively.

[0066] In a possible implementation, the conversion of the frequency and power regulation slope value follows a linear mapping rule. The regulation slope represents the ratio of frequency deviation to power regulation amount, with the unit of MW / Hz. If the regulation responsibility of a unit is 50 MW, and the corresponding frequency regulation range is 0.2 Hz, then the regulation slope is 250 MW / Hz. This parameter is directly written into the control program of the energy storage converter to realize the automatic frequency response function.

[0067] In step S107, the output power set value and the frequency regulation parameter of each unit after adjustment are issued to the remaining units. When the current load rate percentage of any remaining unit exceeds the upper limit value of the battery safe discharge rate or the frequency domain oscillation sign is detected, the power redistribution process and the frequency response coordination are triggered to obtain the stable output power set value and the frequency regulation strategy of each unit.

[0068] The output power set value and frequency adjustment parameter of each unit after adjustment are issued to the remaining units, the instructions are transmitted to each energy storage converter through the communication interface of the energy storage management unit, and the real-time data acquisition program is started to read the DC voltage, output current and frequency deviation value of each remaining unit at a preset sampling period, the current load percentage is calculated according to the ratio of the output current to the rated current, and the real-time operation state data of each unit is obtained. Based on the real-time operation state data, the time-domain waveform of the output power of each unit is analyzed, the periodicity and amplitude change of power fluctuation are identified, if repetitive fluctuation of power is detected within a preset time window and the amplitude exceeds the stable operation threshold, it is determined that there is a frequency domain oscillation sign, and the current load percentage is compared with the upper limit value of the battery safe discharge rate to obtain an abnormal state identifier. According to the abnormal state identifier, if the current load percentage of any remaining unit exceeds the upper limit value of the battery safe discharge rate or there is a frequency domain oscillation sign, a power redistribution process is started, the current available capacity of all remaining units is read, the power distribution value is recalculated according to the capacity proportion, and the frequency response dead zone and adjustment slope parameter of each unit are adjusted to obtain a corrected power distribution scheme. The control instructions of each energy storage unit are updated by using the corrected power distribution scheme, the output power is adjusted by a staged incremental or decremental method, the frequency deviation value in the adjustment process is monitored, if the frequency deviation remains within the allowed range and the power fluctuation amplitude is lower than the stable threshold for a plurality of consecutive sampling periods, the final stable output power set value and frequency adjustment strategy of each unit are determined.

[0069] Specifically, in one embodiment, the energy storage management unit issues control instructions to each energy storage converter through an industrial Ethernet network. Each converter is configured with an independent communication interface that supports the Modbus TCP protocol to ensure real-time and reliable transmission of instructions. The adjusted output power set value is transmitted in 16-bit integer format, with a precision of 0.1 kW. Frequency adjustment parameters include frequency-power droop coefficient, dead zone range, and response delay, among others, which are written into the control register of the converter. The communication interface uses a redundant design, automatically switching to the backup channel when the main channel fails, ensuring the continuity of instruction issuance. The sampling period of the real-time data acquisition program directly affects the monitoring accuracy and system response speed. In a photovoltaic energy storage parallel network, the sampling period is usually set between 100 milliseconds and 1 second. A too short sampling period will increase the communication burden and data processing pressure, while a too long one may miss transient abnormalities. DC voltage is measured by a high-precision voltage sensor, with a measurement range of 600V to 1000V and a resolution of 0.1V. Output current is detected by a Hall current sensor, which can accurately capture current changes within the range of -2000A to +2000A. The frequency deviation value is tracked in real time by a phase-locked loop circuit, compared with the 50Hz reference frequency, and the measurement accuracy is 0.01Hz. The calculation of the current load rate percentage takes into account the temperature correction factor, and the rated current needs to be reduced in high temperature environments. The identification of frequency domain oscillation signs is a key technology to ensure stable operation of the system. Time domain waveform analysis of power fluctuations first requires preprocessing of the collected power data, including removing DC bias and filtering high-frequency noise. Through the sliding time window method, each window contains 10 sampling points of data, and the maximum, minimum, and average values of the power in the window are calculated. When the difference between the maximum and minimum values exceeds 10% of the average value, it is considered that there is significant fluctuation. Periodicity is determined by the autocorrelation function, and if there is a significant peak at a non-zero time delay and the peak value is greater than the threshold, it is determined that there is periodic oscillation. The oscillation period is determined by the time delay corresponding to the peak value, and the oscillation amplitude is the peak-to-peak value of the fluctuation. Frequency domain oscillation signs not only affect the stability of power output, but also may cause false operation of protection devices. When the controller parameters of multiple energy storage units do not match, resonance may occur at a specific frequency point, resulting in periodic fluctuations in power. If this oscillation is not addressed in a timely manner, it will gradually amplify and eventually lead to system instability.

[0070] Preferably, the upper limit of the battery safe discharge rate is dynamically adjusted according to the battery type and operating temperature. The safe discharge rate of a lithium iron phosphate battery at room temperature is usually 1C, i.e. the current corresponding to discharging the entire battery in one hour. When the ambient temperature exceeds 35°C, the safe discharge rate needs to be reduced to 0.8C. The abnormal state identifier uses a bit encoding method, with the 0th bit representing the load rate exceeding the limit and the 1st bit representing the frequency domain oscillation, facilitating quick identification of abnormal types.

[0071] In one possible implementation, the execution of the power re-allocation procedure includes multiple sub-processes. First, the current power allocation state is frozen to prevent instruction conflicts during the adjustment process. Then, real-time state data of all remaining units is read, including current output power, available capacity, temperature state, and historical operation records. The calculation of available capacity not only considers the state of charge of the battery, but also deducts a safety margin, usually reserving 20% of the capacity as an emergency backup. The power re-allocation adopts a proportional allocation principle, and units with larger available capacity bear more power output tasks. The allocation proportion is obtained by solving a linear programming problem, with the objective function being to minimize the variance of all unit load rates, and the constraint conditions including power balance constraints and unit capacity constraints. The adjustment of frequency response parameters needs to be considered in coordination. The frequency response dead zone is set to ±0.05 Hz, and within this range, the energy storage unit does not participate in frequency regulation to avoid frequent action. The adjustment slope is dynamically set according to the available adjustment capacity of the unit, and the unit with larger capacity adopts larger adjustment slope, so that it provides more power support when the frequency deviation occurs. The sum of the adjustment slopes of all units should be equal to the total adjustment demand of the system, to ensure the sufficiency of frequency regulation. Further, the staged adjustment strategy avoids the impact of power mutation on the system. The adjustment process is divided into three stages, the first stage completes 30% of the power adjustment amount within 2 seconds, and observes the system response; the second stage completes 50% of the power adjustment amount within the next 3 seconds; the third stage completes the remaining 20% within the last 2 seconds. A short stability observation period is set between each stage to monitor the changes of frequency and voltage. The stability judgment needs continuous verification of multiple sampling periods. Set 10 consecutive sampling periods as the stability judgment window, each period is 100 milliseconds. Within this window, the frequency deviation must be kept within ±0.1 Hz, and the power fluctuation amplitude should not exceed 2% of the rated power. Only when both conditions are met, the system is considered to be in a stable state. If a new disturbance occurs during the observation period, the counter is reset and the stability judgment process starts again.

[0072] For example, a certain optical storage parallel network contains 6 energy storage units, and unit 3 triggers power redistribution process due to overload protection. It is read that the load rate of unit 3 reaches 95%, which exceeds the safety upper limit of 90%. The available capacities of the other 5 units are 200kW, 300kW, 250kW, 150kW and 400kW respectively. According to the proportional allocation principle, the 100kW power reduced by unit 3 is allocated to other units according to the proportions of 15.4%, 23.1%, 19.2%, 11.5% and 30.8%. The adjustment process adopts a phased manner, and in the first phase, each unit increases 4.6kW, 6.9kW, 5.8kW, 3.5kW and 9.2kW respectively. Monitoring shows that the frequency deviation is maintained within 0.08Hz, and the second phase adjustment continues. After all three phases, it is confirmed that the stable state is reached in the 12th sampling period, and the final power set value and frequency adjustment strategy are determined, realizing the adaptive adjustment after failure.

[0073] In step S108, the continuous power supply time value of the optical storage parallel network is extracted, the overall power supply capacity value of the optical storage parallel network is updated, and the continuous power output and frequency stability of the optical storage parallel network after failure are maintained.

[0074] The power value and the corresponding battery remaining capacity of each energy storage unit are read from the final stable output power set value of each unit. The independent power supply time of each unit is calculated by dividing the remaining capacity by the power value. The minimum power supply time among all units is taken as the continuous power supply time value of the optical storage parallel network, and the network sustainable running time is obtained. According to the network sustainable running time, the instantaneous power output data and DC bus voltage value of the energy storage converter are collected in real time. The network real-time total power is obtained by accumulating the power output of all converters, and the current frequency deviation value is read from the frequency monitoring device. The frequency deviation value is compared with the preset stable threshold value, and the difference between the two is calculated as the percentage of the stable threshold value, which is taken as the system frequency stability margin. Based on the network real-time total power and the system frequency stability margin, the real-time total power is compared with the total power before failure. If the real-time total power reaches the preset recovery proportion of the total power before failure and the frequency stability margin exceeds the safety threshold value, the overall power supply capacity value of the optical storage parallel network is updated to the current real-time total power value, and the continuous power supply time value is recorded, thereby maintaining the continuous power output and frequency stability of the optical storage parallel network after failure.

[0075] Specifically, in an embodiment, the calculation of continuous power supply time is based on the independent running ability evaluation of each energy storage unit. The remaining capacity of each energy storage unit is obtained in real time by the battery management system, which reflects the total amount of energy that the battery can release at present. The independent power supply time is equal to the remaining capacity divided by the current power output value.

[0076] For example, a unit has 800 kWh of remaining capacity and outputs 200 kW, it can run independently for 4 hours. In a parallel network, since each unit needs to run synchronously, the continuous power supply time of the entire network depends on the unit that runs out of power first, that is, the minimum power supply time value among all units. The determination of the network's continuous operation time provides a time reference for monitoring and control. According to this time value, the frequency of data collection and state evaluation is set. When the remaining time is short, the monitoring frequency is correspondingly increased to ensure timely detection of abnormalities and take measures.

[0077] Specifically, the calculation of real-time total power is achieved by accumulating the instantaneous power output of each energy storage converter. Each converter is equipped with a power measurement module with a sampling frequency of up to 10 kHz, which can accurately capture the instantaneous changes in power. The DC bus voltage value is obtained through a voltage sensor to verify the accuracy of the power calculation. Power is equal to voltage multiplied by current, and by comparing the calculated power with the measured power, measurement errors or device abnormalities can be identified. The accumulation process takes into account line losses, and the actual output power is slightly less than the arithmetic sum of the power of each unit.

[0078] Preferably, the calculation of frequency stability margin uses the relative ratio method. The frequency monitoring device continuously tracks the system frequency, updating the frequency measurement value 100 times per second. The current frequency deviation value represents the difference between the real-time frequency and the 50 Hz rated frequency. The preset stability threshold is usually set to 0.2 Hz, representing the maximum frequency deviation that the system can tolerate. The stability margin calculation formula is: stability margin percentage equals the difference between the stability threshold and the frequency deviation value divided by the stability threshold multiplied by 100%. When the frequency deviation is 0.05 Hz and the stability threshold is 0.2 Hz, the stability margin is 75%, indicating that the system still has a large stability margin.

[0079] In one possible implementation, the judgment of power supply capacity update uses dual condition verification. The first condition is the power recovery degree, which requires the real-time total power to reach a preset recovery proportion of the total power before the fault, usually set to 90% or 95%. The second condition is the frequency stability, which requires the frequency stability margin to exceed a safety threshold, generally set to 30%. Only when both conditions are met, the system considers that it has recovered from the fault state to a stable operating state, and at this time the total power supply capacity value is updated.

[0080] Exemplarily, the updated power supply capacity value is used for operation decision-making of the dispatch center. According to this value, the load distribution is arranged to ensure that the actual power supply capacity of the photovoltaic and energy storage parallel network is not exceeded. At the same time, the continuous power supply time information helps the operation and maintenance personnel to arrange the charging plan or backup power supply switching in advance, ensuring the continuity of power supply.

[0081] The above description is only the preferred embodiment of the present application and the explanation of the technical principles. It should be understood by those skilled in the art that the scope of the protection of the present application is not limited to the technical solutions formed by the specific combinations of the above technical features. It should also cover other technical solutions formed by the combinations of the above technical features or their equivalents without departing from the concept of the present application. For example, the technical solutions formed by replacing the above features with the technical features with similar functions disclosed in the present application (but not limited to) and the like.

Claims

1. A method for controlling a light storage parallel network, characterized by, The method comprises: Obtaining the operating state signals of each energy storage unit in the optical storage parallel network, determining the fault isolation object, obtaining the connection relationship and electrical path information of the remaining units after isolation; According to the connection relationship and electrical path information of the remaining units after isolation, the current load rate of each remaining unit is calculated; The real-time output power value of the isolated unit and the amount of frequency regulation responsibility it undertakes are obtained, and combined with the current load rate, the specific power value that needs to be compensated and the frequency regulation responsibility allocation amount are determined; The available residual capacity and frequency regulation bearing capacity of the remaining units are evaluated, and matched with the specific power value that needs to be compensated and the frequency regulation demand to determine the feasible unit combination scheme for fault recovery; The load increase amplitude of each DC bus connection path in the feasible unit combination scheme is evaluated, the connection path that causes the minimum battery temperature rise and the lowest frequency domain coupling risk is identified, and the optimal DC bus connection mode of unit recombination is obtained; According to the optimal DC bus connection mode of unit recombination, a power redistribution list and a frequency regulation responsibility allocation table are generated, and the output power set value and frequency regulation parameter of each unit after adjustment are obtained; The output power set value and frequency regulation parameter of each unit after adjustment are sent to the remaining units, and when the current load rate of any remaining unit exceeds the upper limit of the battery safe discharge rate or the frequency domain oscillation sign is detected, the power redistribution process and frequency response coordination are triggered, and the stable output power set value and frequency regulation strategy of each unit are obtained; The continuous power supply time value of the optical storage parallel network is extracted, and the total power supply capacity value of the optical storage parallel network is updated.

2. The method of claim 1, wherein, The method comprises: Obtaining the operating state signals of each energy storage unit in the optical storage parallel network, determining the fault isolation object, obtaining the connection relationship and electrical path information of the remaining units after isolation; According to the connection relationship and electrical path information of the remaining units after isolation, the current load rate of each remaining unit is calculated; The real-time output power value of the isolated unit and the amount of frequency regulation responsibility it undertakes are obtained, and combined with the current load rate, the specific power value that needs to be compensated and the frequency regulation responsibility allocation amount are determined; The available residual capacity and frequency regulation bearing capacity of the remaining units are evaluated, and matched with the specific power value that needs to be compensated and the frequency regulation demand to determine the feasible unit combination scheme for fault recovery; The load increase amplitude of each DC bus connection path in the feasible unit combination scheme is evaluated, the connection path that causes the minimum battery temperature rise and the lowest frequency domain coupling risk is identified, and the optimal DC bus connection mode of unit recombination is obtained; According to the optimal DC bus connection mode of unit recombination, a power redistribution list and a frequency regulation responsibility allocation table are generated, and the output power set value and frequency regulation parameter of each unit after adjustment are obtained; The output power set value and frequency regulation parameter of each unit after adjustment are sent to the remaining units, and when the current load rate of any remaining unit exceeds the upper limit of the battery safe discharge rate or the frequency domain oscillation sign is detected, the power redistribution process and frequency response coordination are triggered, and the stable output power set value and frequency regulation strategy of each unit are obtained; The continuous power supply time value of the optical storage parallel network is extracted, and the total power supply capacity value of the optical storage parallel network is updated.

3. The method of claim 1, wherein, The method comprises: Obtaining the operating state signals of each energy storage unit in the optical storage parallel network, determining the fault isolation object, obtaining the connection relationship and electrical path information of the remaining units after isolation; According to the connection relationship and electrical path information of the remaining units after isolation, the current load rate of each remaining unit is calculated; The real-time output power value of the isolated unit and the amount of frequency regulation responsibility it undertakes are obtained, and combined with the current load rate, the specific power value that needs to be compensated and the frequency regulation responsibility allocation amount are determined; The available residual capacity and frequency regulation bearing capacity of the remaining units are evaluated, and matched with the specific power value that needs to be compensated and the frequency regulation demand to determine the feasible unit combination scheme for fault recovery; The load increase amplitude of each DC bus connection path in the feasible unit combination scheme is evaluated, the connection path that causes the minimum battery temperature rise and the lowest frequency domain coupling risk is identified, and the optimal DC bus connection mode of unit recombination is obtained; According to the optimal DC bus connection mode of unit recombination, a power redistribution list and a frequency regulation responsibility allocation table are generated, and the output power set value and frequency regulation parameter of each unit after adjustment are obtained; The output power set value and frequency regulation parameter of each unit after adjustment are sent to the remaining units, and when the current load rate of any remaining unit exceeds the upper limit of the battery safe discharge rate or the frequency domain oscillation sign is detected, the power redistribution process and frequency response coordination are triggered, and the stable output power set value and frequency regulation strategy of each unit are obtained; The continuous power supply time value of the optical storage parallel network is extracted, and the total power supply capacity value of the optical storage parallel network is updated.

4. The method of claim 1, wherein, The real-time output power value of the isolation unit and the frequency regulation responsibility it bears are combined with the current load to determine the specific power value that needs to be compensated and the frequency regulation responsibility distribution, including: The real-time output power and frequency regulation responsibility of the isolation unit before the fault are obtained, the proportion of the output power of the isolation unit to the total demand power of the network is calculated to obtain power weight data, the real-time output power is determined as a power gap according to the power weight data, and the regulation power value in the frequency regulation responsibility is extracted to determine a frequency regulation gap; the difference between the maximum carrying capacity of each remaining energy storage unit and the real-time output power is calculated to determine the compensated power value and the frequency regulation responsibility distribution.

5. The method of claim 1, wherein, The available residual capacity and frequency regulation carrying capacity of the remaining units are evaluated and matched with the specific power value that needs to be compensated and the frequency regulation demand to determine a feasible unit combination scheme for fault recovery, including: The difference between the maximum carrying capacity of the remaining energy storage unit and the current output power is calculated to obtain the available residual capacity; the upper and lower limits of the frequency response bandwidth of the remaining energy storage unit are read, the bandwidth range occupied by the current frequency offset is calculated, and the frequency response bandwidth residual is determined; the control parameter configuration of the remaining energy storage unit is read, the parameter difference degree is compared, and the unit pair with frequency domain coupling risk is marked; the unit pair with frequency domain coupling risk is excluded, the combination with the shortest electrical connection path is selected, the residual available power of each unit in the combination is accumulated, and the residual available power is compared with the compensated power value to verify whether the total frequency regulation capacity meets the frequency regulation demand, and the unit combination scheme for fault recovery is determined.

6. The method of claim 1, wherein, The load increase amplitude of each DC bus connection path in the feasible unit combination scheme is evaluated, and the connection path with the smallest unit cell temperature rise and the lowest frequency domain coupling risk is identified to obtain the optimal DC bus connection mode of the unit recombination, including: The current load current and rated carrying capacity of the DC bus connection path in the unit combination scheme are read, the ratio of the current increase to the rated carrying capacity is calculated to obtain the load increase amplitude; the real-time temperature and historical temperature rise rate of the remaining energy storage unit are read, the difference between the expected temperature rise value and the upper limit of the safe temperature is calculated to determine the temperature rise risk level; the frequency response phase difference and amplitude ratio of the remaining energy storage unit are extracted, the phase margin is judged, the frequency domain coupling risk is evaluated, and the path with low temperature rise risk level and frequency domain coupling risk meeting the requirements is marked as a candidate optimization path; the residual capacity of the remaining energy storage unit in the candidate optimization path is divided by the discharge current to obtain the residual discharge time, the weight is set according to the residual discharge time, and the optimal DC bus connection mode is determined.

7. The method of claim 1, wherein, The power redistribution list and frequency regulation responsibility distribution table are generated according to the optimal unit recombination DC bus connection mode, and the output power set value and frequency regulation parameter of each unit after adjustment are obtained, including: The remaining available power of the remaining energy storage units in the optimal DC bus connection mode and the remaining discharge time of the battery are read, the proportion of the remaining discharge time is calculated, and the distribution weight coefficient is obtained; the compensated power value is distributed according to the distribution weight coefficient, and a power distribution list is formed; the frequency response bandwidth overlap range and the adjustment speed difference of the remaining energy storage units are compared, the frequency adjustment responsibility is distributed, and a frequency adjustment responsibility distribution table is generated; according to the power distribution list and the frequency adjustment responsibility distribution table, the output power set value of each unit after adjustment is calculated, and the frequency adjustment responsibility is mapped to a frequency adjustment parameter.

8. The method of claim 1, wherein, The output power set value and the frequency adjustment parameter of each unit after adjustment are issued to the remaining units, and when any remaining unit current load rate exceeds the upper limit value of the battery safe discharge rate or the frequency domain oscillation sign is detected, the power redistribution process and the frequency response coordination are triggered, and the stable output power and the frequency adjustment strategy of each unit are obtained, including: The output power set value and the frequency adjustment parameter are issued to the remaining energy storage units, the DC voltage, the output current and the frequency deviation value are collected, the ratio of the output current to the rated current is calculated, and the current load rate is obtained; the time domain waveform of the current load rate is analyzed, the power fluctuation periodicity and amplitude are identified, and the frequency domain oscillation sign is judged; if any remaining unit current load rate exceeds the upper limit value of the battery safe discharge rate or the frequency domain oscillation sign is abnormal, the power distribution value and the frequency response parameter are recalculated, the output power is adjusted, the frequency deviation is monitored, and the stable output power set value and the frequency adjustment strategy are determined.

9. The method of claim 1, wherein, The continuous power supply time value of the optical storage parallel network is extracted, and the overall power supply capacity value of the optical storage parallel network is updated, including: The power value and the remaining battery capacity of each energy storage unit are read, the remaining battery capacity divided by the power value is calculated, and the minimum power supply time is obtained as the continuous power supply time; the instantaneous power output of the energy storage converter and the DC bus voltage are collected, and the network real-time total power is accumulated; the frequency deviation value of the network real-time total power is read, the difference between the frequency deviation value and the stable threshold is calculated, and the system frequency stability margin is obtained; according to the network real-time total power and the system frequency stability margin, the overall power supply capacity value of the optical storage parallel network is updated.

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