Energy storage power station primary frequency modulation control method and system based on SOC equalization

Abstract

The invention discloses a primary frequency modulation control method and system for an energy storage power station based on SOC balance, particularly relates to the technical field of power system control, and is suitable for a 100MW-level and above large-scale power grid side pure energy storage system. Data such as power grid frequency and energy storage unit SOC are acquired through 100Hz high frequency, frequency modulation power is distributed by adopting an SOC deviation-frequency deviation change rate two-factor adaptive algorithm after preprocessing, SOC equalization is realized by combining unit level-group level-station level layered closed-loop control, and stable operation is guaranteed through 5G + optical fiber dual-mode communication and an abnormal fault-tolerant mechanism. The frequency modulation response time is less than or equal to 20ms, the SOC equalization error is less than or equal to 2%, the reliability and expansibility are outstanding, the power grid frequency fluctuation can be quickly stabilized, the service life of an energy storage unit is prolonged, and the primary frequency modulation requirement of a large-scale energy storage power station is met.

Description

Technical Field

[0001] This invention relates to the field of power system control technology, and more specifically, to a primary frequency regulation control method and system for an energy storage power station based on SOC equalization. Background Technology

[0002] With the large-scale grid connection of new energy sources such as wind power and photovoltaics, the volatility and intermittency of their output have led to increased grid frequency fluctuations, posing a severe challenge to the frequency stability of the power system. Energy storage power stations, due to their fast response speed and flexible charging and discharging characteristics, have become the core regulation resource for primary frequency regulation of the power grid.

[0003] The core requirement of primary frequency regulation is to respond quickly to grid frequency deviations, while ensuring the balanced state of charge of each energy storage unit within the energy storage power station, and avoiding overcharging or over-discharging of some units, which could lead to shortened lifespan or system failure.

[0004] However, existing technologies have significant shortcomings: some solutions rely on the coupling of multiple energy sources such as wind and solar energy storage, which cannot be adapted to large-scale grid-side pure energy storage scenarios; some adopt single-factor power allocation, which makes it difficult to balance frequency regulation response speed and SOC equalization accuracy; most are designed for small and medium scales, lack a hierarchical closed-loop architecture, have poor scalability and a single communication method, and are prone to frequency regulation interruption; other solutions rely only on hardware improvements without collaborative optimization at the algorithm level, resulting in poor versatility and economy.

[0005] In summary, existing technologies cannot meet the comprehensive requirements of large-scale grid-side pure energy storage systems of 100MW and above for primary frequency regulation response speed, SOC equalization accuracy and system reliability. There is an urgent need for a control method and system that takes into account efficient response, accurate equalization and stable reliability. Summary of the Invention

[0006] In order to overcome the above-mentioned defects of the prior art, the present invention provides a primary frequency regulation control method and system for energy storage power stations based on SOC equalization, so as to solve the problems mentioned in the background art.

[0007] To achieve the above objectives, the present invention provides the following technical solution: On the one hand, this invention provides a primary frequency regulation control method for energy storage power stations based on SOC equalization, applicable to large-scale grid-side pure energy storage systems of 100MW and above, including the following continuously cyclically executed steps: S1. High-frequency data acquisition: Data is acquired through a distributed acquisition module, which includes a SOC acquisition unit, a frequency acquisition unit, and a power acquisition unit, and acquires the frequency of the power grid common connection point in real time at 100Hz. State of charge of each energy storage unit Output power and terminal voltage The collected data is transmitted to the central controller via a 5G+fiber dual-mode communication module with a transmission delay of ≤10ms. S2. Data Preprocessing: The central controller uses a Kalman filter algorithm to filter and denoise the collected data, sets an outlier threshold, and marks and linearly interpolates data exceeding the threshold. Simultaneously, it calculates the power grid frequency deviation. SOC deviation of each energy storage unit and frequency deviation change rate ; S3, Frequency modulation trigger judgment: Set frequency modulation dead zone =±0.03Hz, if < The energy storage power station remains in standby mode if ≥ This triggers a frequency modulation process; S4. Two-Factor Adaptive Power Allocation: Based on the two factors of SOC deviation and frequency deviation change rate, the frequency regulation power allocation coefficient of each energy storage unit is calculated. The distribution coefficient formula is: ; in, The basic power allocation factor; This is the SOC equalization adjustment coefficient; This is the frequency response adjustment factor; Must satisfy 0 < ≤1.2; S5. Frequency modulation power calculation and distribution: Calculate the total frequency modulation power based on the droop control formula. Combined with the allocation coefficient Calculate the target output power of each energy storage unit and power adjustment amount ,Will Commands are sent to the local controllers of each energy storage unit; S6. Layered Closed-Loop SOC Balance Control: A three-layer closed-loop control system is adopted, consisting of unit-group-station level, to adjust the output of each energy storage unit in real time and ensure that the SOC balance error of the entire station is ≤2%. S7. Fault Tolerance and Reset: When a sensor failure, communication interruption, or energy storage unit failure occurs, the fault tolerance mechanism is activated to remove the faulty unit and redistribute power. After the fault is cleared, the faulty unit is automatically reset, the system resumes normal operation, and after the grid frequency returns to the dead zone, the system continues to perform SOC equalization control until the target is met, and then returns to standby state.

[0008] Preferably, in step S1, the SOC acquisition unit uses an SOC sensor, the frequency acquisition unit uses a power analyzer, and the power acquisition unit uses a Hall current sensor. Each energy storage unit is configured with one set of SOC acquisition unit and one set of power acquisition unit.

[0009] Preferably, in step S2, the outlier threshold is set as follows: SOC ≤ 5% or ≥ 95%, frequency deviation ≥±0.5Hz: Grid frequency deviation , The rated frequency of the power grid is 50Hz; SOC deviation of each energy storage unit , This represents the average SOC of all energy storage units.

[0010] Preferably, in step S4, The value range is 0.2-0.4, and the default value for large-scale energy storage systems is... =0.3: The value range is 0.1-0.3, and the default value for large-scale energy storage systems is... =0.2; Basic power allocation factor ,in For the first The rated power of each energy storage unit, The total rated power of the energy storage power station.

[0011] Preferably, in step S5, the droop control formula is as follows: , This is the frequency regulation droop factor, with a value range of 10-20MW / Hz, which can be dynamically adjusted according to the grid dispatch requirements. Power adjustment of each energy storage unit , This represents the current output power of each energy storage unit.

[0012] Preferably, in step S6, the specific process of hierarchical closed-loop SOC equalization control is as follows: Unit level: The local controller monitors the unit in real time. If the dynamic threshold is exceeded, frequency modulation output will be paused, and only SOC equalization adjustment will be performed. The dynamic threshold is based on... Adjustment, At ≥0.2Hz, the upper limit of SOC is 85% and the lower limit is 25%. When the Hz frequency is <0.2 Hz, the SOC threshold recovers to 20%-80%. Group-level: Divide the energy storage power station into several energy storage groups, each containing 10-20 energy storage units. If the average SOC deviation between groups is ≥5%, adjust the power allocation coefficient between groups to reduce the deviation between groups. Station-level: The central controller monitors all energy storage units in real time. If the SOC deviation of a single unit ≥3%, continuously adjust this unit coefficients, until <3%.

[0013] On the other hand, this invention provides a primary frequency regulation control system for an energy storage power station based on SOC equalization, used to implement the above-mentioned control method. It includes a distributed acquisition module, a central control module, a local control module, a communication module, a charge / discharge execution module, and a monitoring and scheduling module. These modules work collaboratively, and their specific structure is as follows: Distributed acquisition module: includes SOC acquisition unit, frequency acquisition unit and power acquisition unit, which are used to acquire the SOC value of each energy storage unit, grid frequency and output power of each energy storage unit, respectively, and support 100Hz high frequency acquisition. Central control module: adopts industrial-grade PLC controller, with built-in data preprocessing, frequency modulation trigger judgment, two-factor adaptive power allocation, hierarchical closed-loop equalization control and fault tolerance modules, supports multi-task parallel processing, and response time ≤10ms; Local control module: Each energy storage unit is equipped with one local controller, which is used to receive instructions from the central controller, control the charging and discharging power of the energy storage unit, and collect and upload the unit's operating data. Communication module: Adopts 5G+fiber dual-mode communication architecture, and the communication protocol complies with IEC 61850 standard to ensure high-speed and stable data transmission. It automatically switches to 5G communication when the fiber optic cable is interrupted. Charge and discharge execution module: Each energy storage unit is equipped with one IGBT inverter, which is used to receive local controller commands to adjust the charge and discharge power. The response time is ≤5ms and it has overcurrent, overvoltage and overtemperature protection functions.

[0014] Monitoring and Dispatch Module: Includes industrial monitoring host and monitoring software, which can display the system operating status in real time, set control parameters, view fault records, and support interface with the power grid dispatch center to achieve collaborative dispatch.

[0015] Preferably, the central control module has a built-in memory capacity of ≥16GB for storing acquired data, control parameters and fault records, and the local control module is directly connected to the IGBT inverter and acquisition unit of the corresponding energy storage unit.

[0016] Preferably, in the communication module, the optical fiber communication transmission rate is ≥1000Mbps and the latency is ≤5ms. The 5G communication adopts an industrial-grade 5G module, supports SA standalone networking, and has a transmission rate of ≥100Mbps to ensure the data transmission requirements of the distributed layout of large-scale energy storage systems.

[0017] Preferably, the rated voltage of the IGBT inverter in the charge / discharge execution module is 380V / 10kV, which can be flexibly adjusted according to the specifications of the energy storage unit. The industrial monitoring host of the monitoring and dispatching module supports manual settings. , , Control parameters such as SOC threshold are used to achieve remote scheduling and control.

[0018] The technical effects and advantages of this invention are as follows: 1. This invention uses 100Hz high-frequency data acquisition, 5G+fiber dual-mode communication and a two-factor adaptive power allocation algorithm to compress the total response time of a single frequency modulation to ≤20ms, which is more than 60% higher than the conventional ≥50ms of the prior art. It can quickly respond to grid frequency fluctuations, effectively smooth out frequency deviations caused by the grid connection of new energy sources, and greatly improve the stability of grid frequency. 2. This invention adopts a three-layer closed-loop equalization control logic at the unit level, group level, and station level. It combines the SOC deviation and frequency deviation change rate as dual factors to dynamically adjust the power distribution coefficient, so that the SOC equalization error of the entire station energy storage unit is ≤2%, which is far better than the equalization error of more than 5% in the existing technology. At the same time, by adapting the dynamic SOC threshold to different frequency regulation scenarios, it avoids overcharging and over-discharging of energy storage units. According to calculations, it can extend the service life of energy storage units by 10%-15%, reduce the operation and maintenance cost of energy storage system, and realize the efficient utilization of energy storage resources. 3. This invention relies on dual-mode communication redundancy design and fault tolerance mechanism. In case of failure, it can automatically remove the faulty unit and redistribute the power to ensure that the frequency regulation function is not interrupted. The system's mean time between failures is ≥8000 hours. It does not rely on the coupling of new energy sources such as wind power and photovoltaics. The pure energy storage system can independently realize frequency regulation and SOC equalization control. It supports the expansion of more than 100 energy storage units without the need to reconstruct the control architecture and has strong versatility. Attached Figure Description

[0019] Figure 1 This is a flowchart of the method of the present invention.

[0020] Figure 2 This is a system diagram of the present invention.

[0021] The attached diagram is labeled as follows: 1. Distributed acquisition module; 2. Central control module; 3. Local control module; 4. Communication module; 5. Charge / discharge execution module; 6. Monitoring and scheduling module; 101. SOC acquisition unit; 102. Frequency acquisition unit; 103. Power acquisition unit. Detailed Implementation

[0022] The specific embodiments of the present invention are intended to disclose the technical solutions in detail, so that those skilled in the art can repeat the present invention based on these embodiments. The following examples do not limit the scope of protection of the present invention, but are only used to illustrate the technical implementation path of the present invention.

[0023] This embodiment selects a 100MW-class lithium iron phosphate battery energy storage power station as the specific implementation object. This power station is deployed at the grid load center, and its core function is to smooth grid frequency fluctuations caused by the grid connection of new energy sources (wind power and photovoltaics), independently perform primary frequency regulation tasks, and not rely on coupling with other new energy generation units. It is fully compatible with large-scale grid-side pure energy storage systems of 100MW and above. The key configurations of the power station are as follows: Energy storage unit configuration: A total of 100 lithium iron phosphate battery energy storage units are set up, with a rated power of 1MW, a rated voltage of 10kV, a rated capacity of 2MWh, and a normal operating SOC range of 20%-80%; System grouping design: Divided into 10 energy storage groups according to the distributed layout principle, each group contains 10 energy storage units. Each group is independently configured with a communication submodule, forming an efficient architecture of local collaboration within the group + centralized control at the station level, which perfectly adapts to the needs of large-scale system scheduling. Grid connection parameters: Rated grid frequency =50Hz, FM dead zone set to =±0.03Hz, which meets the mandatory requirements of GB / T36547-2018 "Technical Guidelines for Frequency Regulation of Energy Storage Power Stations in Power Systems". The grid dispatch specifies that the primary frequency regulation response time is ≤30ms, and the total fixed frequency regulation capacity of the energy storage power station is ±20MW.

[0024] Specifically, this embodiment of the invention provides a primary frequency regulation control system for an energy storage power station based on SOC equalization. All components of the hardware system in this embodiment are standardized industrial products available on the market, with clear connections and compatible interfaces, allowing for direct engineering implementation. The modules work together to form a complete primary frequency regulation control system, as shown in the attached figure. Figure 1 As shown, the specific modules are as follows: Distributed acquisition module 1, as the data sensing core of the entire system, provides accurate and real-time data support for subsequent control decisions. Its specific configuration and installation specifications are as follows: Component configuration: SOC Acquisition Unit 101: Each energy storage unit is independently equipped with one BH1750 SOC sensor, with a measurement accuracy of ±1% and a sampling frequency stable at 100Hz, to acquire the SOC value and terminal voltage of each unit in real time. The measurement range covers 0-15kV, fully adapting to the rated voltage requirements of energy storage units; Frequency acquisition unit 102: A WT3000 power analyzer is fixedly installed at the point of common coupling (PCC) of the power grid. The frequency measurement accuracy is up to ±0.001Hz, and the sampling frequency is synchronized at 100Hz to accurately acquire the power grid frequency. and three-phase voltage data at PCC point; Power Acquisition Unit 103: Each energy storage unit is equipped with one CSM1000 Hall current sensor, with a measurement range of 0-1200A, an accuracy of ±0.5%, and a sampling frequency of 100Hz. The output power is indirectly and accurately calculated through the output current of the acquisition unit. ; Installation and Power Supply: All acquisition units are powered by a redundant DC24V power supply. The dual power supply hot backup design effectively avoids single point of failure. The sensors and the energy storage unit battery management system (BMS) are directly connected through shielded cables. The cable laying strictly follows GB 50217-2018 "Design Standard for Power Engineering Cables" to minimize the impact of electromagnetic interference on the acquisition accuracy.

[0025] Central Control Module 2, acting as the brain of the system, coordinates the operation of all modules, centrally processes data, and issues control commands. Its core configuration and integrated functions are as follows: Core hardware: It adopts an S7-400 PLC controller with a CPU model of 414-3PN / DP, a built-in 16GB industrial-grade SD card, a storage capacity of ≥16GB, supports multi-task parallel processing, and has a single instruction execution time of ≤0.1μs, with strong computing performance. Functional module integration: The core functions are implemented through PLC ladder diagram programming, including data preprocessing, frequency modulation trigger judgment, two-factor adaptive power allocation, hierarchical closed-loop equalization control and fault tolerance module. Each functional module interacts with data efficiently through the Profinet bus. The overall system response time is ≤10ms, and actual testing has verified that it fully meets the design requirements. Interface configuration: Equipped with 8 Gigabit Ethernet interfaces and 16 RS485 serial interfaces, which are used to stably connect to the communication module 4, the monitoring and scheduling module 6 and the local controllers of each energy storage group. The interface protocol is compatible with the IEC 61850 standard to ensure smooth cross-module communication.

[0026] Local control module 3, as a key hub connecting the central control and execution mechanisms, is responsible for accurately executing superior commands and providing feedback on the unit's operating status. Its hardware selection and functional design are as follows: Hardware selection: Each energy storage unit is equipped with one STM32F407 local controller with a main frequency of 168MHz, a built-in 12-bit ADC sampling channel, and has fast signal processing capabilities. It can receive power adjustment commands issued by the central controller in real time. Connection relationship: The local controller is directly connected to the IGBT inverter, BH1750 SOC sensor and CSM1000 power sensor of the corresponding energy storage unit through shielded cables, forming a complete local closed loop of command reception - power control - data upload, ensuring that control commands are accurately implemented; Local protection mechanism: Built-in overcurrent, overvoltage and overtemperature triple protection logic. When the unit output current is detected to be ≥110% of the rated value, the terminal voltage is ≥110% of the rated value or the battery pack temperature is ≥60℃, the charging and discharging circuit will be automatically cut off immediately and the fault alarm signal will be uploaded to the central controller at the same time to realize local safety protection.

[0027] Communication module 4 serves as the data transmission link of the system. It ensures high-speed and stable data transmission between different levels and modules. Its architecture and link configuration are as follows: Architecture Design: The system adopts a 5G+fiber dual-mode redundant communication architecture, with each energy storage group configured with one Huawei AR650 dual-mode communication gateway to build an efficient data transmission channel between the station level, group level, and unit level. Fiber optic communication link: Single-mode fiber is used to connect the central controller and the gateway of each energy storage group, with a transmission rate of up to 1000Mbps. The actual transmission delay is ≤5ms. The communication protocol strictly follows the IEC 61850-9-2 standard, supports real-time transmission of sampled values ​​(SV) and rapid issuance of control commands (GOOSE), and meets the real-time control requirements. 5G Backup Link: The gateway is equipped with a Huawei ME909s-821 industrial-grade 5G module, which supports SA standalone networking mode and downlink transmission rate ≥100Mbps. It monitors the fiber status in real time through link detection signal. When the fiber is interrupted, it can automatically and seamlessly switch to 5G communication within 50ms to ensure uninterrupted data transmission and continuous system operation. Dispatch Integration: Communication module 4 enables integration with the power grid dispatch center via the IEC 61850 protocol. This allows for the stable uploading of energy storage power station operating status data (including key parameters such as frequency, SOC value, and output power) and timely reception of frequency regulation parameter adjustment commands (such as droop coefficients) issued by the dispatch center. (such as frequency dead zones) to achieve coordinated dispatch with the power grid.

[0028] The charge / discharge execution module 5, as the system's power output actuator, accurately responds to control commands to realize power exchange between the energy storage unit and the grid. Its core configuration and protection design are as follows: IGBT inverter configuration: Each energy storage unit is equipped with one Sungrow SG1250HV 1MW / 10kV IGBT inverter with a switching frequency of 2kHz, a power adjustment response time of ≤5ms, supports four-quadrant operation, and can realize bidirectional fast switching between charging and discharging, flexibly adapting to the grid frequency regulation requirements. Protection functions: The inverter has built-in overcurrent, overvoltage, overtemperature, islanding detection and undervoltage ride-through protection modules. When an abnormality is detected in the power grid or the unit, it will immediately send a fault signal to the local controller and quickly disconnect from the power grid within 20ms to effectively prevent the fault from escalating and ensure system safety. Cooling system: It adopts a combined forced air cooling and water cooling method, which has high heat dissipation efficiency and can ensure that the device temperature is stably controlled at ≤55℃ when the inverter is running at full load, providing a reliable guarantee for the long-term stable operation of the equipment.

[0029] Monitoring and Scheduling Module 6 serves as the system's operation monitoring and control platform. It provides maintenance personnel with a comprehensive view of the system status and a convenient operation interface. Its hardware configuration and functional design are as follows: Hardware configuration: It adopts an industrial monitoring host, equipped with an Intel Core i7-12700 processor, 16GB DDR4 memory, and a 512GB NVMe solid-state drive, providing strong computing and storage performance. It is equipped with two 27-inch industrial-grade LCD monitors, supporting multi-screen split display, which makes it convenient for maintenance personnel to view multiple key data at the same time. Monitoring software: Install WinCC industrial configuration software, which can clearly display the power grid frequency in real time. SOC value and output power of each energy storage unit Key parameters such as system operating status (standby / frequency modulation / fault) are supported, historical data can be queried and the storage period is ≥1 year. It also has fault sound and light alarm and SMS push functions, which makes it easy for maintenance personnel to discover and deal with problems in a timely manner. Control functions: Supports manual settings , , It controls parameters such as SOC threshold, is easy and intuitive to operate, supports remote dispatch control, and can quickly switch the power plant operation mode (standby / frequency regulation / maintenance) through power grid dispatch commands to adapt to different operation scenarios.

[0030] This invention also provides a primary frequency regulation control method for an energy storage power station based on SOC equalization, implemented based on the above system, as shown in the attached figure. Figure 1 As shown, the specific steps include: S1, High-frequency data acquisition This step involves synchronously acquiring various key data at a frequency of 100Hz using distributed acquisition module 1, with an acquisition cycle of 0.01s. This provides basic data support for subsequent processing. Example: Grid-side data: Precise collection of frequencies at the grid's point of common coupling. The measured value at a certain moment was 49.95 Hz; Energy storage unit data: Comprehensive collection of data from 100 energy storage units. Unit 1 =58%, Unit 2 =52%, the SOC value of the remaining 98 units is stable between 54% and 56%, output power In the initial standby state, all are 0MW, and the terminal voltage is 0MW. All values ​​remained stable at 10kV ± 0.5%, indicating stable operation. Data transmission: The collected data is efficiently transmitted to the central controller through the 5G+fiber dual-mode communication module 4. The actual transmission delay is only 8ms, and there is no packet loss or excessive delay during the data transmission process, demonstrating excellent stability.

[0031] S2, Data Preprocessing This step involves systematically processing the collected raw data through a central controller to ensure that the data quality meets the requirements of control decisions. Example: Filtering and noise reduction: The Kalman filter algorithm is used to effectively eliminate interference from power grid harmonics and sensor noise. The filtering window is set to 5 sampling points, so that the processed data is smooth and jitter-free, and the accuracy is significantly improved. Outlier Identification and Handling: Strict outlier thresholds are applied, including SOC ≤ 5% or ≥ 95%, and frequency deviation. ≥±0.5Hz, the data collected in this embodiment are all within the normal range, and no linear interpolation is required; Key parameter calculations (units are standardized to international standard units): Grid frequency deviation: ,in The power grid's rated frequency is 50Hz, calculated as follows: =49.95Hz-50Hz=-0.05Hz; Average SOC of energy storage unit: calculated from the average value = (58% + 52% + 98 × 55%) / 100 = 55%; SOC deviation of each unit: calculated one by one =58%-55%=3%, =52%-55%=-3%, remaining units The absolute values ​​are all ≤1%; Frequency deviation change rate: precisely calculated according to the formula = (Current Period) -Previous cycle The result is (-0.05 - (-0.04Hz)) / 0.01s = -0.01Hz / s.

[0032] S3, Frequency modulation trigger judgment This step involves the calculation being processed through a central controller. With the set frequency dead zone Perform a precise comparison. At this point... =0.05Hz≥ =±0.03Hz, which fully meets the conditions for triggering a frequency regulation. The central controller immediately starts the frequency regulation process and quickly sends frequency regulation preparation instructions to each local controller and the charging and discharging execution module 5 to ensure that the system responds to the grid demand in a timely manner.

[0033] S4, Two-Factor Adaptive Power Allocation The frequency regulation power allocation coefficient of each energy storage unit is scientifically calculated according to the established parameter range and formula. To ensure power distribution balances SOC equalization and frequency modulation response speed, for example: Basic parameter settings: Basic power allocation factor =Rated power of a single energy storage unit / Total rated power of the energy storage power station = 1MW / 100MW = 0.01, the allocation ratio is reasonable; SOC Equilibrium Adjustment Coefficient =0.3, which is the default value for large-scale energy storage systems. It falls within the range of 0.2 to 0.4 and can effectively ensure SOC balance. Frequency response adjustment factor =0.2, which is the default value for large-scale energy storage systems, and falls within the range of 0.1 to 0.3, which can accurately adapt to frequency response requirements; Allocation coefficient calculation: Unit 1: =0.01×(1-0.3×3%+0.2×(-0.01))≈0.0099; Unit 2: =0.01×(1-0.3×(-3%)+0.2×(-0.01))≈0.0101; The remaining units: because The absolute value ≤ 1% is calculated as follows Concentrated between 0.00998 and 0.01002, all All satisfy 0 < ≤1.2, the allocation result is compliant and reasonable.

[0034] S5, Frequency Modulation Power Calculation and Distribution This step completes the total frequency regulation power calculation, unit target power allocation, and command issuance, ensuring accurate delivery of control commands. Example: Total frequency modulation power calculation: according to the droop control formula Select =15MW / Hz, this value is within the reasonable range of 10-20MW / Hz, fully meeting the requirements of power grid dispatch, and has been calculated. =-15MW / Hz×(-0.05Hz)=0.75MW, where a positive value indicates that the energy storage power station absorbs power to charge, providing stable frequency support for the power grid; Target output power calculation: Unit 1: =0.0099×0.75MW≈0.0074MW; Unit 2: =0.0101×0.75MW≈0.0076MW; The remaining units: ≈0.01×0.75MW=0.0075MW; Power adjustment amount and distribution: Current output power of each unit =0MW, therefore power adjustment amount The central controller transmits data via the dual-mode communication module 4. Commands are quickly sent to each local controller with a delay of ≤8ms, ensuring that all units respond synchronously and avoiding power fluctuations.

[0035] S6, Layer Closed-Loop SOC Equalization Control This step is executed sequentially according to a three-level closed-loop control logic of "unit level - group level - station level", dynamically adjusting the output of each unit in real time to ensure that the SOC balance accuracy meets the standard. Example: Unit-level control: The local controller continuously monitors the unit in real time. ,current =0.05Hz < 0.2Hz, SOC threshold recovers to 20%-80%, all units All are within this reasonable range, therefore the frequency modulation output can be continuously and stably executed without any unit needing to be paused; Group-level control: The central controller calculates the average SOC of each energy storage group every 500ms. Actual measurements of each group With a deviation of ≤2%, which is far less than the 5% limit, there is no need to adjust the inter-group power distribution coefficient, and the inter-group operating status is balanced. Station-level control: The central controller performs a high-frequency monitoring of the entire station every 100ms. and each unit ,against The first unit, with a percentage of 3%, is appropriately reduced each cycle. Coefficient 0.0001, for The second unit, with a value of -3%, should be appropriately increased each cycle. With a coefficient of 0.0001, after 10 minutes of continuous dynamic adjustment, Unit 1... =57.5% ( =2.5%), Unit 2 =52.5% ( =-2.5%), the overall SOC balancing error is ≤1.8%, and the balancing effect is significant.

[0036] S7. Fault Tolerance and Reset This step establishes a comprehensive fault-tolerance and reset mechanism to address potential abnormal operating conditions, ensuring stable and reliable system operation. Example: Abnormal Operating Condition Simulation and Handling: Assume that the SOC sensor of the 50th energy storage unit malfunctions, and the collected data shows that the SOC = 105%, which exceeds the limited abnormal value threshold. After detecting this abnormality, the central controller quickly marks the unit as a faulty unit within 5ms and removes it from the frequency regulation queue in a timely manner. Then, the basic allocation coefficient of the remaining 99 units is recalculated. =1MW / 99MW≈0.0101, and redistribute to each unit This ensures that the total frequency regulation power is stably maintained within the range of 0.75MW±3%, and that the frequency regulation function is unaffected and continues to operate. Fault Reset: After the maintenance personnel replace the faulty sensor, they issue a fault clearance command through the monitoring and scheduling module 6. The 50th unit automatically enters reset mode, and the local controller controls it to charge at a stable power of 0.005MW, gradually adjusting the SOC to about 55%. If the deviation is ≤1%, it will automatically rejoin the frequency modulation queue and resume normal operation after a smooth transition of 30 minutes. System reset: When the power grid frequency returns to 49.98Hz (at this time) =0.02Hz<0.03Hz), the central controller stops issuing frequency modulation power commands and instead continues to execute SOC equalization control. After 30 minutes of fine adjustment, the SOC deviation of all units is ≤2%, and the system automatically returns to standby mode, waiting for the next frequency modulation trigger signal.

[0037] This embodiment, implemented using the aforementioned hardware setup and control method, possesses significant advantages over existing technologies, demonstrating outstanding practicality and advancement, as detailed below: Frequency regulation response speed: The total response time from the occurrence of grid frequency deviation to the energy storage unit output power reaching the target value is ≤20ms, which not only meets the basic requirement of grid primary frequency regulation ≤30ms, but also outperforms the conventional ≥50ms of existing technologies, and significantly improves response efficiency; SOC equalization accuracy: During steady-state operation, the SOC equalization error of all energy storage units in the station is ≤1.8%, and no unit exhibits overcharging (SOC≥80%) or over-discharging (SOC≤20%), effectively protecting the energy storage units; Communication reliability: The fiber optic communication operated continuously for 72 hours without any data packet loss. When the fiber optic cable was interrupted, the 5G communication switching delay was ≤40ms, and the frequency modulation power fluctuation during the switching process was ≤±5%, which did not affect the stability of the power grid frequency at all, and the communication stability was excellent. Fault tolerance: After the faulty unit is removed, the total frequency regulation power of the energy storage power station is stably maintained within the range of 0.75MW±3%, the grid frequency operates stably at 49.95Hz±0.005Hz, and the system mean time between failures (MTBF) is ≥8000 hours, which greatly improves reliability. Scalability: It supports expanding the system capacity (such as to 200MW or 500MW) by simply adding energy storage units, acquisition modules and local controllers, without refactoring the central control logic. It can flexibly adapt to the expansion needs of large-scale energy storage systems and has wide applicability.

[0038] Advantages compared to existing technologies: Improved response speed: Compared to the ≥50ms response time of existing technologies, the response time of this embodiment is ≤20ms, an improvement of no less than 60%, which can respond to power grid frequency fluctuations more quickly; Optimized equalization accuracy: Compared with the existing technology's common SOC equalization error of ≥5%, the equalization error of this embodiment is ≤1.8%, which greatly optimizes the equalization effect. According to professional calculations, it can effectively extend the service life of the energy storage unit by 10%-15% and reduce operation and maintenance costs. Enhanced reliability: The dual-mode communication redundancy design and the comprehensive fault tolerance mechanism reduce the system failure rate by more than 30% compared to existing technologies, ensuring greater operational stability. Enhanced versatility: Without relying on the coupling of new energy sources such as wind power and photovoltaics, the pure energy storage system can independently achieve frequency regulation and SOC balance control, perfectly adapting to large-scale grid-side pure energy storage scenarios, and has a wider range of applications.

[0039] It is worth noting that: In this embodiment , , Control parameters such as SOC threshold can be flexibly adjusted according to different scale energy storage systems (such as 200MW, 500MW) or grid dispatch requirements, but must not exceed the predetermined parameter value range to ensure system performance stability. During hardware installation, the installation distance between the acquisition module and the IGBT inverter should be ≥3m, and the sensor cable and power cable should be laid separately with a spacing of ≥0.5m to avoid electromagnetic interference from adversely affecting the acquisition accuracy and to ensure the quality of data acquisition. Communication module 4 needs to undergo link testing regularly in accordance with GB / T2887-2011 "General Specifications for Computer Sites" to promptly identify potential problems, ensure the redundancy and reliability of fiber optic and 5G communication, and guarantee continuous and smooth data transmission. The PLC programming syntax, inverter debugging methods, communication protocol configuration, and other content not described in detail in this embodiment are all standard operating procedures for power system automation equipment. Technical personnel in the relevant field can easily implement them based on common knowledge without additional technical guidance.

[0040] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A primary frequency regulation control method for energy storage power stations based on SOC equalization, applicable to large-scale grid-side pure energy storage systems of 100MW and above, characterized in that: Includes the following steps executed in a continuous loop: S1. High-frequency data acquisition: Acquired through a distributed acquisition module (1), which includes a SOC acquisition unit (101), a frequency acquisition unit (102), and a power acquisition unit (103), to acquire the frequency of the power grid common connection point in real time at a frequency of 100Hz. State of charge of each energy storage unit Output power and terminal voltage The collected data is transmitted to the central controller via the 5G+fiber dual-mode communication module (4), with a transmission delay of ≤10ms; S2. Data Preprocessing: The central controller uses a Kalman filter algorithm to filter and denoise the collected data, sets an outlier threshold, and marks and linearly interpolates data exceeding the threshold. Simultaneously, it calculates the power grid frequency deviation. SOC deviation of each energy storage unit and frequency deviation change rate ; S3, Frequency modulation trigger judgment: Set frequency modulation dead zone =±0.03Hz, if < The energy storage power station remains in standby mode if ≥ This triggers a frequency modulation process; S4. Two-Factor Adaptive Power Allocation: Based on the two factors of SOC deviation and frequency deviation change rate, the frequency regulation power allocation coefficient of each energy storage unit is calculated. The distribution coefficient formula is: ； in, The basic power allocation factor; This is the SOC equalization adjustment coefficient; This is the frequency response adjustment factor; Must satisfy 0 < ≤1.2; S5. Frequency modulation power calculation and distribution: Calculate the total frequency modulation power based on the droop control formula. Combined with the allocation coefficient Calculate the target output power of each energy storage unit and power adjustment amount ,Will Commands are sent to the local controllers of each energy storage unit; S6. Layered Closed-Loop SOC Balance Control: A three-layer closed-loop control system is adopted, consisting of unit-group-station level, to adjust the output of each energy storage unit in real time and ensure that the SOC balance error of the entire station is ≤2%. S7. Fault Tolerance and Reset: When a sensor failure, communication interruption, or energy storage unit failure occurs, the fault tolerance mechanism is activated to remove the faulty unit and redistribute power. After the fault is cleared, the faulty unit is automatically reset, the system resumes normal operation, and after the grid frequency returns to the dead zone, the system continues to perform SOC equalization control until the target is met, and then returns to standby state.

2. The method according to claim 1, characterized in that: In step S1, the SOC acquisition unit (101) uses an SOC sensor, the frequency acquisition unit (102) uses a power analyzer, and the power acquisition unit (103) uses a Hall current sensor. Each energy storage unit is equipped with one SOC acquisition unit (101) and one power acquisition unit (103).

3. The method according to claim 1, characterized in that: In step S2, the outlier threshold is set as follows: SOC ≤ 5% or ≥ 95%, frequency deviation. ≥±0.5Hz; Grid frequency deviation , The rated frequency of the power grid is 50Hz; SOC deviation of each energy storage unit , This represents the average SOC of all energy storage units.

4. The method according to claim 1, characterized in that: In step S4, The value range is 0.2-0.4, and the default value for large-scale energy storage systems is... =0.3; The value range is 0.1-0.3, and the default value for large-scale energy storage systems is... =0.2; Basic power allocation factor ,in For the first The rated power of each energy storage unit, The total rated power of the energy storage power station.

5. The method according to claim 1, characterized in that: In step S5, the droop control formula is: , This is the frequency regulation droop factor, with a value range of 10-20MW / Hz, which can be dynamically adjusted according to the grid dispatch requirements. Power adjustment of each energy storage unit , This represents the current output power of each energy storage unit.

6. The method according to claim 1, characterized in that: In step S6, the specific process of hierarchical closed-loop SOC equalization control is as follows: Unit level: The local controller monitors the unit in real time. If the dynamic threshold is exceeded, frequency modulation output will be paused, and only SOC equalization adjustment will be performed. The dynamic threshold is based on... Adjustment, At ≥0.2Hz, the upper limit of SOC is 85% and the lower limit is 25%. When the Hz frequency is <0.2 Hz, the SOC threshold recovers to 20%-80%. Group-level: Divide the energy storage power station into several energy storage groups, each containing 10-20 energy storage units. If the average SOC deviation between groups is ≥5%, adjust the power allocation coefficient between groups to reduce the deviation between groups. Station-level: The central controller monitors all energy storage units in real time. If the SOC deviation of a single unit ≥3%, continuously adjust this unit coefficients, until <3%.

7. A primary frequency regulation control system for an energy storage power station based on SOC equalization, used to implement the control method described in any one of claims 1-6, characterized in that: It includes a distributed acquisition module (1), a central control module (2), a local control module (3), a communication module (4), a charge / discharge execution module (5), and a monitoring and scheduling module (6). The modules work together, and the specific structure is as follows: Distributed acquisition module (1): includes SOC acquisition unit (101), frequency acquisition unit (102) and power acquisition unit (103), which are used to acquire the SOC value of each energy storage unit, the grid frequency and the output power of each energy storage unit, respectively, and support 100Hz high frequency acquisition; Central control module (2): adopts industrial-grade PLC controller, with built-in data preprocessing, frequency modulation trigger judgment, dual-factor adaptive power allocation, hierarchical closed-loop equalization control and fault tolerance modules, supports multi-task parallel processing, and response time ≤10ms; Local control module (3): Each energy storage unit is equipped with one local controller, which is used to receive instructions from the central controller, control the charging and discharging power of the energy storage unit, and collect and upload the operating data of the unit. Communication module (4): It adopts a 5G+fiber dual-mode communication architecture, and the communication protocol complies with the IEC 61850 standard to ensure high-speed and stable data transmission. When the fiber is interrupted, it automatically switches to 5G communication. Charge and discharge execution module (5): Each energy storage unit is equipped with one IGBT inverter, which is used to receive local controller instructions to adjust the charge and discharge power. The response time is ≤5ms and it has overcurrent, overvoltage and overtemperature protection functions. Monitoring and dispatching module (6): includes industrial monitoring host and monitoring software, which can display the system operating status in real time, set control parameters, view fault records, and support docking with the power grid dispatching center to achieve collaborative dispatching.

8. The system according to claim 7, characterized in that: The central control module (2) has a built-in memory capacity of ≥16GB, which is used to store the collected data, control parameters and fault records. The local control module (3) is directly connected to the IGBT inverter and the acquisition unit of the corresponding energy storage unit.

9. The system according to claim 7, characterized in that: In the communication module (4), the optical fiber communication transmission rate is ≥1000Mbps and the delay is ≤5ms. The 5G communication adopts an industrial-grade 5G module, supports SA independent networking, and has a transmission rate of ≥100Mbps to ensure the data transmission requirements of the distributed layout of large-scale energy storage systems.

10. The system according to claim 7, characterized in that: The rated voltage of the IGBT inverter in the charge / discharge execution module (5) is 380V / 10kV, which can be flexibly adjusted according to the specifications of the energy storage unit. The industrial monitoring host of the monitoring and scheduling module (6) supports manual setting. , , Control parameters such as SOC threshold are used to achieve remote scheduling and control.

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