A power control method, medium and device of a light storage system

Abstract

This application discloses a power control method, medium, and device for a photovoltaic-storage system. The method includes the following steps: real-time acquisition and analysis of grid-side status signals; if the power change rate exceeds a set first threshold and the duration exceeds a set second threshold, an instantaneous full-load request is generated, and a corresponding first power control command is issued directly to the energy storage cabinet of the photovoltaic-storage system to execute instantaneous full-load power control; if a voltage deviation or frequency deviation exceeds a set limit, an active or reactive power support request is generated, and a corresponding second power control command is issued directly to the energy storage converter and / or photovoltaic inverter to execute active or reactive power control. The medium and device are used to implement the above method. The beneficial effects of this application are: it solves the problems of slow response speed, low control accuracy, and insufficient multi-energy coordination in the prior art, providing an efficient and stable solution for the control of photovoltaic-storage systems under complex operating conditions.

Description

Technical Field

[0001] This application relates to the field of new energy power generation technology, and in particular to a power control method, medium and equipment for a photovoltaic energy storage system. Background Technology

[0002] In existing technologies, power control of energy storage systems primarily relies on power commands sent by the power grid. Target power is calculated and then distributed to each energy storage unit. For example, the controller allocates the target power to each energy storage unit based on the total power command from the grid and the percentage of remaining power in each unit to achieve power balance. However, this method requires step-by-step calculation of the power command, resulting in low processing efficiency and difficulty in handling instantaneous full-capacity demands. Furthermore, existing technologies use the same algorithm (such as traditional PID control) for power control of both photovoltaic and energy storage systems, failing to consider the delay characteristics of photovoltaic systems caused by fluctuations in sunlight. This leads to lag in control response and affects the overall system's dynamic adjustment capability. Summary of the Invention

[0003] One objective of this application is to provide a power control method for a photovoltaic energy storage system that can solve at least one of the defects in the aforementioned background art.

[0004] Another object of this application is to provide a computer-readable storage medium capable of implementing a power control method for an optical storage system that addresses at least one of the defects in the aforementioned background art.

[0005] Another object of this application is to provide an electronic device capable of implementing a power control method for an optical energy storage system that solves at least one of the defects in the above-mentioned background art.

[0006] To achieve at least one of the above objectives, one aspect of this application provides a power control method for a photovoltaic-storage system, comprising the following steps: acquiring and analyzing state signals from the grid side in real time to obtain power change rate, voltage deviation, and frequency deviation; if the power change rate is detected to exceed a set first threshold and the duration exceeds a set second threshold, generating an instantaneous full-load request and generating a corresponding first power control command; directly sending the generated first power control command to the energy storage cabinet of the photovoltaic-storage system to perform instantaneous full-load power control; if the voltage deviation or frequency deviation is detected to exceed a set limit, generating an active or reactive power support request and generating a corresponding second power control command; directly sending the generated second power control command to the energy storage converter and / or photovoltaic inverter of the photovoltaic-storage system to perform active or reactive power control.

[0007] Preferably, the process of the energy storage cabinet performing instantaneous full power control is as follows: after receiving the instantaneous full power request, the full power of the energy storage cabinet is determined according to the maximum discharge power, rated power and real-time SOC of the energy storage cabinet; according to the full power of each energy storage cabinet, a first power control command is generated to operate each energy storage cabinet at full power and sent to the corresponding energy storage cabinet.

[0008] Preferably, the minimum value between the maximum discharge power and the rated power of the energy storage cabinet is taken as the full power output.

[0009] Preferably, the full-power output of the energy storage cabinet is calculated using the following formula: P m =P0×(K×SOC T -SOC th ); In the formula, P m P0 represents the rated power of the energy storage unit, K represents the proportional coefficient, and SOC represents the full-capacity power of the energy storage unit. T This represents the real-time SOC value of the energy storage unit. th This indicates the preset lower limit of the SOC value for the energy storage cabinet.

[0010] Preferably, the energy storage converter and the photovoltaic inverter of the photovoltaic-storage system simultaneously receive the second power control command and collaboratively execute active or reactive power control. Specifically, the photovoltaic inverter calculates an output reference value with early response based on the received second power control command using a first PID control algorithm with delay compensation, and performs power control according to the output reference value. The energy storage converter calculates a compensated output value based on the error between the actual output power of the photovoltaic inverter and the second power control command using a second PID control algorithm, and performs power control according to the compensated output value. The response speed of the second PID control algorithm is faster than that of the first PID control algorithm.

[0011] Preferably, during the operation of the photovoltaic inverter, the gain of the first PID control algorithm is dynamically adjusted according to the illuminance and the rate of change of illuminance. Specifically, when the illuminance is greater than a preset first intensity threshold in a strong light environment, the proportional gain in the first PID control algorithm is reduced while the derivative gain is increased; when the illuminance is less than a preset second intensity threshold in a weak light environment, the proportional gain in the first PID control algorithm is increased while the integral gain is reduced; when the illuminance changes abruptly at a rate of change of illuminance greater than or equal to a preset third intensity threshold, the proportional gain in the first PID control algorithm is increased while the integral gain is reduced.

[0012] Preferably, during the operation of the energy storage converter, the working scenario of the energy storage converter is determined based on the real-time SOC of all energy storage cabinets. The working scenarios of the energy storage converter include low power scenario, normal power scenario, and high power scenario. Based on the working scenario of the energy storage converter and the current power change rate, the gain of the second PID control algorithm is dynamically adjusted. Specifically, when the energy storage converter is in a low power scenario, the proportional gain in the second PID control algorithm is reduced; when the energy storage converter is in a normal power scenario, the proportional gain in the second PID control algorithm is set to its maximum value; when the energy storage converter is in a high power scenario, the proportional gain in the second PID control algorithm is reduced; when the photovoltaic-energy storage system is in a power oscillation scenario where the power change rate at the grid connection point is greater than or equal to a preset third threshold, the derivative gain in the second PID control algorithm is increased.

[0013] Preferably, the expressions for the first PID control algorithm and the second PID control algorithm are as follows: ; ; In the formula, This represents the output reference value of the photovoltaic inverter at time t. This represents the voltage or frequency deviation at time t. Represents the photovoltaic delay time constant. , , These represent the proportional gain, integral gain, and derivative gain corresponding to the first PID control algorithm, respectively. This represents the compensated output value of the energy storage converter at time t. This represents the error between the actual output power of the photovoltaic inverter at time t and the second power control command. , , These represent the proportional gain, integral gain, and derivative gain corresponding to the second PID control algorithm, respectively.

[0014] Another aspect of this application provides a computer-readable storage medium storing a computer program; when the computer program is executed by a processor, it implements the power control method of the optical storage system described above.

[0015] Another aspect of this application provides an electronic device, including a processor and a memory; the memory is used to store a computer program, and the processor is used to execute the computer program to implement the power control method of the above-described optical storage system.

[0016] Compared with the prior art, the beneficial effects of this application are as follows: (1) This application eliminates the delay of traditional power command calculation by directly sending the generated power control command to the corresponding execution device, and significantly improves the response speed in instantaneous full power scenario.

[0017] (2) This application generates corresponding power control commands for different grid operating conditions such as instantaneous full power generation, voltage drop, and frequency fluctuation, and directly sends them to the corresponding execution devices. This differentiated command generation and distribution mechanism enables the photovoltaic-storage system to quickly switch control modes under different grid disturbance scenarios, significantly improving the system's dynamic adjustment capability and grid support capability under complex operating conditions. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the working steps of this application; Figure 2 This is a schematic diagram of the active power control process of the photovoltaic-storage system under normal operating conditions in this application; Figure 3 This is a schematic diagram of the reactive power control process of the photovoltaic-storage system under normal operating conditions in this application. Detailed Implementation

[0019] The present application will now be further described in conjunction with specific embodiments. It should be noted that, in the description of this specification, the use of terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicates that the specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms should not be construed as necessarily referring to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. In addition, those skilled in the art can combine and integrate the different embodiments or examples described in this specification.

[0020] In the description of this application, it should be noted that the terms "center", "lateral", "longitudinal", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", etc., which indicate the orientation and positional relationship based on the orientation or positional relationship shown in the accompanying drawings, are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and should not be construed as limiting the specific protection scope of this application.

[0021] It should be noted that the terms "first," "second," etc., in the specification and claims of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence.

[0022] In this application, unless otherwise expressly specified and limited, the terms "installation," "connection," "joining," and "fixing," etc., should be interpreted broadly. For example, they can refer to a connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0023] In this application, unless otherwise expressly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature being directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature being directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0024] The terms “comprising” and “having”, and any variations thereof, in the specification and claims of this application are intended to cover non-exclusive inclusion, for example, a process, method, system, product, or device that includes a series of steps or units is not necessarily limited to those steps or units that are explicitly listed, but may include other steps or units that are not explicitly listed or that are inherent to such process, method, product, or device.

[0025] One aspect of this application provides a power control method for a photovoltaic energy storage system, such as... Figure 1 As shown, one preferred embodiment includes the following steps: S100: Real-time acquisition of grid-side status signals and analytical calculations to obtain power change rate, voltage deviation, and frequency deviation.

[0026] It should be understood that the power change rate reflects the magnitude of change in active power at the grid connection point per unit time, and is a key indicator for identifying whether the power grid is experiencing a large power deficit or impulsive load switching. Voltage deviation reflects the degree of deviation between the actual voltage at the grid connection point and the rated voltage; the causes of voltage deviation include: insufficient or excessive reactive power in the system, line voltage drop, and sudden load changes. Frequency deviation reflects whether the active power of the power grid is balanced, and is a key indicator for identifying whether the power grid needs active power support.

[0027] S200: If the power change rate is detected to exceed the set first threshold and the duration exceeds the set second threshold, an instantaneous full-load request is generated and a corresponding first power control command is generated; the generated first power control command is directly sent to the energy storage cabinet of the photovoltaic energy storage system to execute instantaneous full-load power control.

[0028] It should be understood that when a large-capacity generator trips or DC power outages occur in the power grid, the active power at the grid connection point changes drastically within a very short time. Traditional solutions require waiting for the dispatch center to calculate and issue power commands, followed by tiered allocation, resulting in a response time of 100-200ms, which cannot meet the power grid's demand for rapid power output support from photovoltaic and energy storage systems. This step achieves autonomous and rapid identification of instantaneous full-power demand by calculating the power change rate locally in real time and setting threshold judgments.

[0029] S300: If the voltage deviation or frequency deviation exceeds the set limit, an active or reactive power support request is generated and a corresponding second power control command is generated; the generated second power control command is directly sent to the energy storage converter and / or photovoltaic inverter of the photovoltaic-storage system to perform active or reactive power control.

[0030] It should be understood that the voltage stability and frequency stability of the power grid depend on reactive power balance and active power balance, respectively. When the voltage at the grid connection point deviates from the rated value (voltage drop or sudden rise), it indicates an imbalance in the system's reactive power, requiring the injection or absorption of reactive power for voltage support. When the frequency at the grid connection point deviates from the rated value (frequency decrease or increase), it indicates an imbalance in the system's active power, requiring an increase or decrease in active power for frequency support. This step, through real-time monitoring and limit judgment of voltage and frequency deviations, achieves autonomous and rapid identification of voltage support requirements (corresponding to reactive power support requests) and frequency support requirements (corresponding to active power support requests). Furthermore, in a photovoltaic-storage system, both the energy storage converter and the photovoltaic inverter can achieve active and reactive power regulation; therefore, the generated second power control command can be issued to one of the energy storage converter and the photovoltaic inverter, or simultaneously to both.

[0031] Understandably, the technical solution based on this application eliminates the latency of traditional power command step-by-step calculation by directly issuing the generated power control commands to the corresponding execution devices, significantly improving the response speed in instantaneous full-load scenarios. Simultaneously, for different grid operating conditions such as instantaneous full-load, voltage dips, and frequency fluctuations, corresponding power control commands are generated and directly issued to the corresponding execution devices. This differentiated command generation and distribution mechanism enables the photovoltaic-storage system to quickly switch control modes under different grid disturbance scenarios, significantly improving the system's dynamic adjustment capability and grid support capability under complex operating conditions.

[0032] The executing devices include energy storage cabinets, energy storage converters, and photovoltaic inverters; that is, the executing device for issuing the first power control command is the energy storage cabinet, and the executing device for issuing the second power control command is the energy storage converter and / or photovoltaic inverter.

[0033] In a specific embodiment, when executing step S100, the status signals on the grid side can be obtained from the measurement devices installed at the grid connection point, or they can be obtained from high-frequency status signals directly issued by the dispatching side. The status signals obtained by the grid connection point include grid voltage, grid frequency, real-time active power, and real-time reactive power. The high-frequency status signals issued by the dispatching side include instantaneous full-load flag, emergency support flag, voltage drop event trigger signal, voltage surge event trigger signal, and frequency fluctuation event trigger signal.

[0034] It is important to know that the entire process of step S100 is executed through the controller of the photovoltaic-storage system; the controller can receive status signals from the grid side via hardwired connections or a communication network. For ease of understanding, the specific analytical calculation process will be described in detail below using the status signals collected at the grid connection point as an example.

[0035] In a specific example, the controller calculates the power change rate using a numerical differential algorithm based on the real-time active power value at the grid connection point; the controller calculates the voltage deviation by comparing the effective voltage value at the grid connection point with the rated voltage; and the controller calculates the frequency deviation by comparing the grid frequency at the grid connection point with the rated frequency. The specific calculation expressions for the power change rate, voltage deviation, and frequency deviation are as follows: ; ; .

[0036] In the formula, Indicates the rate of change of power. This represents the real-time value of active power at time t. This represents the real-time value of active power at the previous sampling time. Indicates the sampling interval time. Indicates voltage deviation. This represents the grid voltage at time t. Indicates the rated voltage. Indicates frequency deviation. This represents the power grid frequency at time t. Indicates the rated frequency.

[0037] In a specific embodiment, when performing step S200, the specific values ​​of the first threshold and the second threshold can be selected according to the actual needs of those skilled in the art; for example, the range of the first threshold is (5%~25%)P. N / s, the second threshold ranges from 3 to 10ms; where P N This indicates the total rated power of the photovoltaic-storage system.

[0038] It is understandable that the first threshold is 10% × P. N / s, taking a second threshold of 5ms as an example; when the detected power change rate is greater than 10% × P N When the power supply signal is received in a value of 1 / s and lasts for more than 5ms, it is determined that there is a severe power disturbance in the power grid. The photovoltaic and energy storage system needs to immediately output power at its maximum capacity to support the system. Therefore, a full power request is generated and a corresponding first power control command is generated.

[0039] It should be understood that the first power control command includes the following information: command type (instantaneous full power generation), target value (full power generation), and execution device identifier (corresponding energy storage cabinet number). The controller directly sends the first power control command to the corresponding energy storage cabinet through the communication network, without going through intermediate links such as total power calculation and cabinet-level power allocation. The end-to-end latency is ≤10ms, which can effectively cope with the instantaneous full power generation demand of the power grid. In contrast, traditional solutions require multiple intermediate links such as "power grid command reception, total power calculation, cabinet-level power allocation, and command issuance", with a latency of about 100-200ms.

[0040] In one specific embodiment, the photovoltaic-energy storage system includes multiple energy storage cabinets. Since the rated power, health status, and real-time State of Charge (SOC) of different energy storage cabinets vary, sending the same full-power command to all cabinets (e.g., operating at rated power) could lead to over-discharge damage to some cabinets with lower SOCs, while some cabinets with higher SOCs might fail to fully utilize their discharge capacity. Therefore, in this embodiment, the full-power output of each energy storage cabinet can be determined based on its real-time status differences. Based on the full-power output of each cabinet, a first power control command is generated to operate each cabinet at full power and sent to the corresponding cabinet.

[0041] It should be noted that there are multiple ways to determine the full power output of each energy storage unit based on the real-time status differences of each unit. To facilitate understanding, two specific examples will be used to illustrate this in detail below.

[0042] In a specific example, the controller collects the maximum discharge power of the energy storage cabinet. This maximum discharge power is dynamically calculated by the battery management system of the photovoltaic-energy storage system based on real-time factors such as battery temperature, health status, and voltage within the cabinet. The specific calculation process is well-known to those skilled in the art and will not be described in detail here. The collected maximum discharge power is compared with the rated power of the energy storage cabinet, and the smaller value is taken as the full-capacity power. For example, if the rated power of the energy storage cabinet is 50kW and the maximum discharge power output by the battery management system is 45kW, then the full-capacity power of the energy storage cabinet is 45kW.

[0043] It is important to understand that by taking the smaller value, we can ensure that the full power output command issued is actually achievable and safe for the energy storage cabinet under any operating condition, thus avoiding control failures or equipment protection actions caused by unreachable commands.

[0044] In another specific example, the full-power output of the energy storage cabinet is calculated using the following formula: P m =P0×(K×SOC T -SOC th ).

[0045] In the formula, P m P0 represents the rated power of the energy storage cabinet, and K represents the proportional gain, which ranges from 0.5 to 0.8 and is mainly used to provide a safety margin. SOC (State of Charge) represents the full-capacity power of the energy storage cabinet. T This represents the real-time SOC value of the energy storage unit. th This indicates the preset lower limit of SOC for the energy storage cabinet. The specific value can be determined by those skilled in the art based on their actual needs, for example, it can be 20%.

[0046] Understandably, based on the above calculation formula, the full-power output of the energy storage cabinet changes linearly with the real-time State of Charge (SOC). That is, the higher the real-time SOC of the energy storage cabinet, the greater its full-power output, and vice versa, thus automatically achieving power balance among the energy storage cabinets. By setting a lower limit for SOC, it is ensured that the energy storage cabinet will not continue to discharge when the SOC value is below the lower limit.

[0047] It should be noted that when (K×SOC) T -SOC th When the value of ) is less than or equal to 0, the full power of the corresponding energy storage cabinet is 0, that is, the energy storage cabinet will no longer discharge to protect the battery.

[0048] To further facilitate understanding of the technical solution of this application, the specific processes of active power control and reactive power control performed by the photovoltaic energy storage system under normal operating conditions will be described in detail below.

[0049] In a specific embodiment, such as Figure 2 As shown, the active power control process for a photovoltaic-storage system includes time-of-use pricing control, demand control, anti-reverse current control, backup power control, and photovoltaic-storage collaborative control.

[0050] For the time-of-use (TOU) pricing control process, the controller acquires local TOU policy data, including the division of peak, normal, and off-peak periods and the corresponding electricity purchase price for each period. Based on the current time period, the controller generates the charging and discharging demand for the energy storage system: during off-peak periods, it generates charging demand and charges the energy storage system at the maximum permissible power; during peak periods, it generates discharging demand, prioritizing the energy storage system to supply power to the load, reducing the cost of purchasing electricity from the grid. The controller can pre-store multiple sets of TOU parameter tables and receive time period division and price information from the grid or dispatch center via a communication interface, enabling dynamic updates to the TOU pricing strategy.

[0051] For demand control, the controller monitors the active power at the grid connection point in real time and calculates the average power within the sliding window as the demand value. Based on users' historical electricity consumption data and basic electricity billing standards, the controller sets target limits for demand control. When it is predicted that the current demand value will exceed the set demand limit, the controller generates energy storage discharge demand, and the energy storage system supplements part of the load power, reducing the power drawn from the grid. The demand control process can be superimposed on the time-of-use pricing control process, setting lower demand limits during peak electricity price periods to minimize demand-related electricity costs, achieving coordinated control of "peak-time discharge to reduce demand, and off-peak charging to store energy."

[0052] For the anti-reverse current control process, the controller monitors the power direction and magnitude at the grid connection point in real time to prevent the electricity generated by the photovoltaic system or energy storage system from being fed back into the grid. A positive power value at the grid connection point indicates that power is flowing from the grid to the user, while a negative power value indicates that power is flowing from the user back to the grid (i.e., reverse current). The controller sets a reverse current judgment threshold, and triggers the anti-reverse current action when the reverse power exceeds this threshold. Specifically, when a reverse current trend is detected, the controller first performs flexible adjustment by reducing the active power output of the photovoltaic inverter (power limiting control) or reducing the discharge power of the energy storage; when flexible adjustment cannot eliminate the reverse current, a protection action is triggered to quickly disconnect the grid-connected cabinet. The anti-reverse current control process requires coordinating the balance between photovoltaic power generation, energy storage charging and discharging power, and load power.

[0053] For backup power control, the controller executes a backup power reservation strategy during the daily charging and discharging management of the energy storage system based on preset backup power capacity requirements. The controller sets the required backup power capacity (expressed as a percentage of State of Charge (SOC) or absolute capacity) based on the power demands of critical loads and the expected backup power duration. During the daily operation of the energy storage system, the controller deducts the backup power capacity from the available capacity and does not participate in economic dispatching such as peak-valley arbitrage or demand control. When the energy storage SOC drops to the backup power capacity threshold, the controller stops discharging to ensure that the backup power capacity is not consumed. When a grid outage is detected, the controller immediately switches the energy storage system to backup power mode, allocating power according to the priority of critical loads to ensure continuous power supply to critical loads.

[0054] In the photovoltaic-energy storage coordinated control process, the controller coordinates the active power allocation of the photovoltaic system and the energy storage system. The controller obtains the real-time SOC of each energy storage unit through the battery management system. When the real-time SOC of the energy storage unit reaches the upper limit threshold (e.g., 95%), the controller stops charging or reduces the charging power; when the real-time SOC of the energy storage unit drops to the lower limit threshold (e.g., 20%), the controller stops discharging or limits the discharging power. The battery management system adjusts the SOC of each individual cell in the battery pack corresponding to the energy storage unit through active or passive balancing methods, making the state of charge of each cell more consistent, preventing safety hazards caused by overcharging or over-discharging of individual cells, and maximizing the overall usable capacity of the battery pack. The controller sends the energy storage active power target value to each energy storage inverter through the communication interface to control the charging and discharging power of the energy storage system. The controller sends the photovoltaic active power target value to the photovoltaic data acquisition device, which forwards it to each photovoltaic inverter to control the active power output of the photovoltaic inverter.

[0055] It's important to understand that active power output control for photovoltaic (PV) inverters includes power curtailment control and curtailment control. Power curtailment control limits the active power output of PV inverters when PV power generation exceeds system demand or grid-connected capacity limits. Curtailment control proactively reduces PV power generation and forgoes some PV output in extreme situations (such as grid peak shaving or anti-reverse current requirements).

[0056] In a specific embodiment, such as Figure 3As shown, the reactive power control process for a photovoltaic-storage system includes the following steps: The controller receives reactive power adjustment commands from the grid dispatch or Automatic Voltage Reactive Power Control (AVC) system via a communication interface. These commands include, but are not limited to: power factor commands (e.g., requiring a power factor of at least 0.95 at the grid connection point), reactive power commands (e.g., requiring the grid connection point to inject or absorb a specified amount of reactive power), and voltage commands (e.g., requiring the grid connection point voltage to be maintained within ±5% of the rated voltage). Based on the received reactive power adjustment commands and combined with real-time voltage and active power data at the grid connection point, the controller generates a target reactive power value for the grid connection point. Using the deviation between the target reactive power value and the actual reactive power at the grid connection point as input error, the controller calculates the total reactive power that needs to be compensated through PID closed-loop control. The controller limits the calculated total reactive power demand to ensure it does not exceed the total reactive power adjustment capacity of the photovoltaic-storage system, thus avoiding the issuance of reactive power commands exceeding the system's capacity. The controller performs coordinated control of photovoltaic and energy storage systems, allocating the total reactive power demand to the energy storage system and the photovoltaic system. Specifically, the controller prioritizes energy storage and sends reactive power instructions allocated to the energy storage system to the energy storage converter through the communication interface, controlling the energy storage converter to generate or absorb the corresponding reactive power. The controller also sends reactive power instructions allocated to the photovoltaic system to the photovoltaic data acquisition device, which forwards them to each photovoltaic inverter, controlling the photovoltaic inverter to participate in reactive power regulation.

[0057] It's important to understand that the control logic of the energy storage priority principle is as follows: due to the fast response speed of energy storage converters (dynamic response time can reach the millisecond level) and high reactive power regulation accuracy, the total reactive power demand is initially borne by the energy storage system. When the reactive power regulation capacity of the energy storage system is insufficient (e.g., the energy storage SOC is too high or too low, limiting output, or the energy storage converter has reached its capacity limit), the photovoltaic inverter supplements the remaining reactive power demand. The controller assesses the available reactive power capacity of the energy storage system and the photovoltaic system in real time and dynamically adjusts the allocation ratio between the two.

[0058] It is understandable that the control process of a photovoltaic-storage system under normal operating conditions prioritizes economy and daily dispatch. However, when the grid experiences voltage or frequency exceedances, it indicates that the system voltage or frequency has deviated from its safe operating range. At this point, the control objective must immediately shift from "economic dispatch" to "grid safety support." However, conventional control strategies do not consider emergency support needs, and both the photovoltaic and energy storage systems use the same algorithm (such as traditional PID control) for power control, failing to account for the delay characteristics of the photovoltaic system caused by light fluctuations. This results in a lag in control response, affecting the overall system's dynamic adjustment capability. Therefore, when voltage or frequency support needs arise, the technical solution of this application provides an active and reactive power control strategy based on improved PID control. This strategy utilizes the faster response speed of the energy storage system compared to the photovoltaic system to compensate for the photovoltaic output. For ease of understanding, a detailed description follows.

[0059] In one specific embodiment, during step S300, the energy storage converter and the photovoltaic inverter of the photovoltaic-storage system simultaneously receive a second power control command and collaboratively execute active or reactive power control. Specifically, the photovoltaic inverter calculates an output reference value with advance response based on the received second power control command using a first PID control algorithm with delay compensation, and then performs power control according to the output reference value. The energy storage converter calculates a compensated output value based on the error between the actual output power of the photovoltaic inverter and the second power control command using a second PID control algorithm, and then performs power control according to the compensated output value.

[0060] Understandably, the first PID control algorithm adds a second-order derivative delay compensation term to the traditional PID algorithm, which can compensate for the inherent 50-100ms response delay of the photovoltaic system. The photovoltaic inverter operates according to the calculated output reference value, and its response characteristic is designed as "slow tracking" to suppress power disturbances caused by sudden changes in sunlight. The parameters of the second PID control algorithm are designed as "fast response" so that it can quickly track error changes and compensate for the output deviation of the photovoltaic system in a timely manner. The collaborative logic of the two PID control algorithms is: photovoltaic slow tracking, energy storage fast compensation; that is, the photovoltaic system slowly tracks the target value according to its inherent response speed, while the energy storage system quickly compensates for the power gap that the photovoltaic system fails to respond to in time, so that the overall power output of the photovoltaic and energy storage system quickly and accurately tracks the target command. For ease of understanding, the specific expressions of the first and second PID control algorithms will be described below.

[0061] In a specific example, the expressions for the first PID control algorithm and the second PID control algorithm are as follows: .

[0062] .

[0063] In the formula, This represents the output reference value of the photovoltaic inverter at time t. This represents the voltage or frequency deviation at time t. It represents the photovoltaic delay time constant, which can range from 50 to 100 ms. It characterizes the inherent lag time of the photovoltaic system from receiving the command to the actual output power change, and can be adaptively adjusted with the light intensity. , , These represent the proportional gain, integral gain, and derivative gain corresponding to the first PID control algorithm, respectively. This represents the compensated output value of the energy storage converter at time t. This represents the error between the actual output power of the photovoltaic inverter at time t and the second power control command. , , These represent the proportional gain, integral gain, and derivative gain corresponding to the second PID control algorithm, respectively.

[0064] Understandably, in the first PID control algorithm, This is the required delay compensation term; based on the photovoltaic delay time constant. The delay compensation term, in this embodiment, the first PID control algorithm is equivalent to forward calculation; that is, predicting the delay time. To what extent will the internal error develop, so as to issue a correction command in advance to compensate for the inherent delay of the photovoltaic system.

[0065] It should be understood that the operating environment of a photovoltaic system is constantly changing. Under strong sunlight conditions, the output power of the photovoltaic system is high and relatively stable. In this case, PID control is needed to prioritize stability and avoid overshoot and oscillation. Under weak sunlight or sudden changes in sunlight conditions, the output power of the photovoltaic system is low and fluctuates drastically. In this case, PID control is needed to prioritize response speed and quickly track power changes. If fixed PID parameters are used, it is impossible to simultaneously meet the control requirements of extreme conditions such as strong sunlight, weak sunlight, and sudden changes in sunlight. Therefore, during the operation of the photovoltaic inverter, in this embodiment, the gain of the first PID control algorithm can be dynamically adjusted according to the light intensity and the rate of change of light intensity. For ease of understanding, a detailed description will be provided below.

[0066] In a specific embodiment, the process of dynamically adjusting the gain of the first PID control algorithm based on the light intensity and the rate of change of light intensity is as follows: When in a strong light environment where the light intensity is greater than a preset first intensity threshold, the proportional gain in the first PID control algorithm is decreased, while the derivative gain is increased. When in a weak light environment where the light intensity is less than a preset second intensity threshold, the proportional gain in the first PID control algorithm is increased, while the integral gain is decreased. When in a sudden light change environment where the rate of change of light intensity is greater than or equal to a preset third intensity threshold, the proportional gain in the first PID control algorithm is increased, while the integral gain is decreased.

[0067] It is understandable that solar irradiance can be characterized by the power generation per unit area of ​​a photovoltaic panel; the greater the power generation per unit area, the stronger the solar irradiance, and vice versa. Therefore, the rate of change of solar irradiance can be characterized by the rate of change of power generation per unit area. The specific values ​​of the first, second, and third intensity thresholds can be selected according to the actual needs of those skilled in the art; for example, the range of the first intensity threshold can be 400~500W / m. 2 The second intensity threshold can be in the range of 200~300W / m. 2 The third intensity threshold can be in the range of 40~60W / m. 2 ·s.

[0068] In a specific example, the first intensity threshold is set to 500 W / m. 2 The second intensity threshold is set at 200 W / m. 2 The third intensity threshold is set at 50 W / m. 2 For example, when the light intensity Q > 500 W / m². 2 At that time, the proportional gain Adjust the differential gain while reducing it. The light intensity is increased to improve stability and suppress overshoot. When the light intensity Q < 200 W / m² 2 At that time, the proportional gain Adjust upwards, and simultaneously adjust the integral gain. The intensity is lowered to improve response speed and avoid integral saturation. (When the light intensity is 200W / m²) 2 ≤Q≤500W / m 2 At that time, proportional gain Integral gain Differential gain All values ​​remain at their initial values. When the rate of change of light intensity dQ / dt ≥ 50 W / m 2 At time s, the proportional gain Adjust upwards, and simultaneously adjust the integral gain. The response speed is reduced to avoid integral saturation.

[0069] It should be understood that the operation of an energy storage system is significantly constrained by its State of Charge (SOC). The charging and discharging capabilities and control strategies of the energy storage system should differ across different SOC ranges. Specifically, at low SOCs, discharge power should be limited to protect the batteries; at high SOCs, charging power should be limited to prevent overcharge; and within the normal SOC range, the rapid response capability of the energy storage system should be fully utilized. Furthermore, when power oscillations occur in the photovoltaic-energy storage system, the damping characteristics of the energy storage system need to be enhanced to suppress the oscillations. Based on the above analysis, if the second PID control algorithm uses fixed PID parameters, it will be unable to simultaneously meet the control requirements of different SOC ranges and different dynamic operating conditions. Therefore, during the operation of the energy storage converter, in this embodiment, the gain of the second PID control algorithm can be dynamically adjusted based on the real-time SOC of all energy storage cabinets and the power changes at the current grid connection point. For ease of understanding, a detailed description will follow.

[0070] In one specific embodiment, the operating scenario of the energy storage converter is determined based on the real-time SOC of all energy storage cabinets. The operating scenarios of the energy storage converter include low power scenario, normal power scenario, and high power scenario. The specific process of dynamically adjusting the gain of the second PID control algorithm based on the operating scenario of the energy storage converter and the current power change rate is as follows: When the energy storage converter is in a low power scenario, the proportional gain in the second PID control algorithm is reduced. When the energy storage converter is in a normal power scenario, the proportional gain in the second PID control algorithm is set to maximum. When the energy storage converter is in a high power scenario, the proportional gain in the second PID control algorithm is reduced. When the photovoltaic-energy storage system is in a power oscillation scenario where the power change rate at the grid connection point is greater than or equal to a preset third threshold, the derivative gain in the second PID control algorithm is increased.

[0071] It is understandable that the SOC of an energy storage system is the sum of the real-time SOCs of all energy storage cabinets; when determining the operating scenario of an energy storage converter, the SOC value of the energy storage system should be used as the basis for judgment. The judgment criteria for different operating scenarios can be set according to the actual needs of those skilled in the art; for example, when the SOC of the energy storage system is less than 20%~30%, the energy storage converter is determined to operate in a low-power scenario; when the SOC of the energy storage system is greater than 70%~80%, the energy storage converter is determined to operate in a high-power scenario; and when the SOC of the energy storage system is between the above two situations, the energy storage converter is determined to operate in a normal-power scenario. The third threshold used for judging power oscillation scenarios can be set according to the actual needs of those skilled in the art; for example, the value range can be (20%~30%)P. N / s; where P NThis indicates the total rated power of the photovoltaic-storage system.

[0072] In a specific example, assuming the energy storage system's SOC is between 30% and 80% under normal power conditions, the third threshold is set to 30% × P. N Taking / s as an example. When the SOC of the energy storage system is <30%, the proportional gain is... The output power of the energy storage system is reduced to prevent over-discharge of the battery. When the SOC of the energy storage system is between 30% and 80%, the proportional gain is adjusted. Set to the maximum value to enable the energy storage system to have the fastest response speed. When the energy storage system's SOC > 80%, the proportional gain... The charging power of the energy storage system is reduced to prevent overcharging of the battery. This applies when the power change rate at the grid connection point, dP / dt, is ≥ 30% × P. N At / s, the differential gain The differential damping effect is enhanced by adjusting the damping upwards, thus suppressing power oscillations.

[0073] Another aspect of this application provides a computer-readable storage medium, in a preferred embodiment of which a computer program is stored on the storage medium; when the computer program is executed by a processor, the power control method of the optical storage system described above is implemented.

[0074] Another aspect of this application provides an electronic device, in one preferred embodiment of which includes a processor and a memory; the memory is used to store a computer program, and the processor is used to execute the computer program to implement the power control method of the optical storage system described above.

[0075] The basic principles, main features, and advantages of this application have been described above. Those skilled in the art should understand that this application is not limited to the above embodiments. The embodiments and descriptions in the specification are merely the principles of this application. Various changes and modifications can be made to this application without departing from its spirit and scope, and all such changes and modifications fall within the scope of the claims. The scope of protection claimed by this application is defined by the appended claims and their equivalents.

Claims

1. A power control method for a photovoltaic-storage system, characterized in that, Includes the following steps: Real-time acquisition and analysis of grid-side status signals are performed to obtain power change rate, voltage deviation, and frequency deviation. If the power change rate is detected to exceed the set first threshold and the duration exceeds the set second threshold, an instantaneous full-load request is generated and a corresponding first power control command is generated; the generated first power control command is directly sent to the energy storage cabinet of the photovoltaic energy storage system to execute instantaneous full-load power control; If a voltage or frequency deviation is detected to exceed the set limit, an active or reactive power support request is generated and a corresponding second power control command is generated. The generated second power control command is directly sent to the energy storage converter and / or photovoltaic inverter of the photovoltaic-storage system to perform active or reactive power control.

2. The power control method for a photovoltaic-storage system as described in claim 1, characterized in that, The process of the energy storage cabinet performing instantaneous full-power control is as follows: Upon receiving a request for instantaneous full power generation, the full power generation capacity of the energy storage cabinet is determined based on the maximum discharge power, rated power, and real-time SOC of the energy storage cabinet. Based on the full power output of each energy storage cabinet, a first power control command is generated to operate each energy storage cabinet at full power output, and then sent to the corresponding energy storage cabinet.

3. The power control method for a photovoltaic-storage system as described in claim 2, characterized in that, The minimum of the maximum discharge power and the rated power of the energy storage cabinet is taken as the full power output.

4. The power control method for a photovoltaic-storage system as described in claim 2, characterized in that, The full-capacity power of the energy storage unit is calculated using the following formula: P m =P0×(K×SOC T -SOC th ); In the formula, P m P0 represents the rated power of the energy storage unit, K represents the proportional coefficient, and SOC represents the full-capacity power of the energy storage unit. T This represents the real-time SOC value of the energy storage unit. th This indicates the preset lower limit of the SOC value for the energy storage cabinet.

5. The power control method for a photovoltaic-storage system as described in claim 1, characterized in that, In a photovoltaic-storage system, both the energy storage converter and the photovoltaic inverter simultaneously receive a second power control command and collaboratively execute active or reactive power control. The specific process is as follows: The photovoltaic inverter calculates the output reference value for early response using the first PID control algorithm with delay compensation based on the received second power control command, and performs power control according to the output reference value. The energy storage converter calculates the compensation output value based on the error between the actual output power of the photovoltaic inverter and the second power control command using the second PID control algorithm, and performs power control according to the compensation output value. The second PID control algorithm has a faster response speed than the first PID control algorithm.

6. The power control method for a photovoltaic-storage system as described in claim 5, characterized in that, During the operation of the photovoltaic inverter, the first PID control algorithm is dynamically adjusted based on the light intensity and the rate of change of light intensity. The specific process is as follows: When in a strong light environment where the light intensity is greater than a preset first intensity threshold, the proportional gain in the first PID control algorithm is reduced while the derivative gain is increased. When in a weak light environment where the light intensity is less than the preset second intensity threshold, the proportional gain in the first PID control algorithm is increased, while the integral gain is decreased. When the light intensity change rate is greater than or equal to the preset third intensity threshold in a sudden light change environment, the proportional gain in the first PID control algorithm is increased, while the integral gain is decreased.

7. The power control method for a photovoltaic-storage system as described in claim 5, characterized in that, During the operation of the energy storage converter, the working scenario of the energy storage converter is determined based on the real-time SOC of all energy storage cabinets. The working scenarios of the energy storage converter include low power scenario, normal power scenario, and high power scenario. Based on the working scenario of the energy storage converter and the current power change rate, the second PID control algorithm is dynamically adjusted for gain. The specific process is as follows: When the energy storage converter is in a low-power scenario, the proportional gain in the second PID control algorithm is reduced. When the energy storage converter is in a normal power scenario, the proportional gain in the second PID control algorithm is set to the maximum value; When the energy storage converter is in a high-power scenario, the proportional gain in the second PID control algorithm is reduced. When the power oscillation scenario of the photovoltaic-storage system at the grid connection point is greater than or equal to the preset third threshold, the derivative gain in the second PID control algorithm is increased.

8. The power control method for a photovoltaic-storage system as described in claim 5, characterized in that, The expressions for the first PID control algorithm and the second PID control algorithm are as follows: ； ； In the formula, This represents the output reference value of the photovoltaic inverter at time t. This represents the voltage or frequency deviation at time t. Represents the photovoltaic delay time constant. , , These represent the proportional gain, integral gain, and derivative gain corresponding to the first PID control algorithm, respectively. This represents the compensated output value of the energy storage converter at time t. This represents the error between the actual output power of the photovoltaic inverter at time t and the second power control command. , , These represent the proportional gain, integral gain, and derivative gain corresponding to the second PID control algorithm, respectively.

9. An electronic device, characterized in that, It includes a processor and a memory; the memory is used to store a computer program, and the processor is used to execute the computer program to implement the power control method of the optical storage system as described in any one of claims 1-8.

10. A computer-readable storage medium, characterized in that, The storage medium stores a computer program; when the computer program is executed by a processor, it implements the power control method of the optical storage system as described in any one of claims 1-8.

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