Power coordination control method for participation of energy storage inverter in power grid frequency modulation

Abstract

The invention relates to the field of power grid power control, in particular to a power coordination control method for an energy storage inverter to participate in power grid frequency modulation. The method comprises the following steps: firstly, according to a charge state value of an energy storage unit at a current moment and a received power instruction value, predicting a charge state of the energy storage unit at each moment in a preset future time period after the current moment, screening out a pre-quit energy storage unit, and based on the charge state value of each pre-quit energy storage unit at the current moment, determining a pre-quit energy storage unit according to the pre-quit energy storage unit. And obtaining the predicted residual service duration of each pre-quit energy storage unit, constructing an optimization function and a constraint condition of the power grid system according to the power instruction value and the charge state value of each energy storage unit at the current moment and the predicted residual service duration of each pre-quit energy storage unit, and combining the optimization function and the constraint condition to obtain the power grid system. And obtaining the optimal power instruction value of each energy storage unit at the current moment. According to the invention, the power coordination effect of each energy storage unit can be improved, and secondary disturbance of the power grid frequency is avoided.

Description

Technical Field

[0001] This invention relates to the field of power grid control, and more specifically to a power coordination control method for energy storage inverters participating in power grid frequency regulation. Background Technology

[0002] Energy storage inverters play an important role in the field of grid frequency regulation. They can realize the mutual conversion between the AC power of the grid and the DC power of energy storage units (such as batteries). In the process of grid frequency regulation, the coordinated control of the power of each energy storage unit is not a simple "simultaneous charging and discharging", but a necessary requirement to achieve the optimal system performance, the best economy, the longest life and the most reliable safety.

[0003] In related technologies, when grid frequency instability occurs, energy storage inverters typically use algorithms such as droop control or virtual synchronization to control the charging and discharging power of energy storage units according to a fixed ratio, thereby filling the power gap in the grid system and stabilizing the grid frequency. However, due to the inconsistency in the initial state of charge and aging degree of different energy storage units, if the charging and discharging of each energy storage unit is carried out according to a fixed ratio, some energy storage units will immediately stop operating when their charge exceeds the limit, thereby increasing the operating burden of other energy storage units and further causing secondary disturbances to the grid frequency. This results in poor power coordination among energy storage units during grid frequency regulation. Summary of the Invention

[0004] To address the technical problem of poor power coordination among energy storage units during grid frequency regulation, this invention aims to provide a power coordination control method for energy storage inverters participating in grid frequency regulation. The specific technical solution adopted is as follows:

[0005] This invention proposes a power coordination control method for energy storage inverters participating in grid frequency regulation, the method comprising:

[0006] Real-time acquisition of the state of charge value of each energy storage unit in the power grid system and the power command value received by each energy storage unit;

[0007] Taking any energy storage unit as the target energy storage unit, based on the target energy storage unit's state of charge (SOC) value at the current moment and the received power command value, predict the target energy storage unit's SOC value at each moment within a preset future time period after the current moment; based on whether the predicted SOC value of each energy storage unit at the last moment within the preset future time period is within a preset safety range, select pre-exit energy storage units from all energy storage units; based on the SOC value of each pre-exit energy storage unit at the current moment, obtain the estimated remaining service time of each pre-exit energy storage unit;

[0008] Based on the power command value and state of charge value of each energy storage unit at the current moment, and the expected remaining service time of each energy storage unit to be decommissioned, an optimization function and constraints for the power grid system are constructed; based on the optimization function and constraints, the optimal power command value of each energy storage unit at the current moment is obtained.

[0009] Furthermore, the predicted state of charge value of the target energy storage unit at each time point within a preset future time period after the current time includes:

[0010] The product of the power command value received by the target energy storage unit at the current moment, the duration between each moment in the preset future time period and the current moment, and the preset efficiency coefficient is used as the numerator, the rated capacity of the target energy storage unit is used as the denominator, and the opposite of the ratio is used as the change in the state of charge of the target energy storage unit at each moment in the preset future time period.

[0011] The sum of the state of charge value of the target energy storage unit at the current moment and the change in the state of charge of the target energy storage unit at each moment within a preset future time period is used as the predicted state of charge value of the target energy storage unit at each moment within the preset future time period.

[0012] Furthermore, if the power command value received by the target energy storage unit at the current moment is greater than 0, then the preset efficiency coefficient is set to 1; if the power command value received by the target energy storage unit at the current moment is less than 0, then the preset efficiency coefficient ranges from 1 to 1. .

[0013] Furthermore, the step of selecting pre-retirement energy storage units from all energy storage units includes:

[0014] If the predicted state of charge value of the target energy storage unit at the last moment of the preset future time period is not within the preset safety range, the target energy storage unit will be marked as a pre-exit energy storage unit.

[0015] Furthermore, the preset safety range is .

[0016] Furthermore, obtaining the estimated remaining service time for each pre-retirement energy storage unit includes:

[0017] If any pre-exit unit is taken as the target pre-exit unit, and the power command value received by the target pre-exit unit at the current time is greater than 0, then the expected remaining service time of the target pre-exit unit is obtained based on the difference between the state of charge value of the target pre-exit unit at the current time and the lower limit of the preset safety range, the power command value received by the target pre-exit unit at the current time, the rated capacity of the target pre-exit unit and the preset efficiency coefficient.

[0018] If the power command value received by the target pre-exit unit at the current moment is less than 0, the estimated remaining service time of the target pre-exit unit is obtained based on the difference between the state of charge value of the target pre-exit unit at the current moment and the upper limit of the preset safety range, the power command value received by the target pre-exit unit at the current moment, the rated capacity of the target pre-exit unit, and the preset efficiency coefficient.

[0019] Furthermore, the estimated remaining service time of the target pre-exit unit includes:

[0020] Based on the calculation formula for the estimated remaining service time, the estimated remaining service time of the target pre-exit unit is obtained. The calculation formula for the estimated remaining service time is as follows:

[0021]

[0022] in, Indicates the estimated remaining service time of the target pre-exit unit; This represents the state of charge value of the target pre-exit unit at the current moment; Indicates the lower limit of the preset safety range; Indicates the upper limit of the preset safety range; Indicates the rated capacity of the target pre-exit unit; Indicates the preset efficiency coefficient; This represents the power command value received by the target pre-exit unit at the current moment.

[0023] Furthermore, the optimization function and constraints for constructing the power grid system include:

[0024] The optimization function is:

[0025]

[0026]

[0027] in, Represents the optimization function of the power grid system; and They represent the first The energy storage unit in the preset future time period The moment and the The decision variable at time t, i.e., the independent variable of the optimization function, when hour, For the first The power command value of the energy storage unit at the current moment, and the preset power command value for the next time period. The moment and the Each moment is two adjacent moments; Indicates the first The power command value received by each energy storage unit at the current moment; Indicates the first Preset adjustment weights for each energy storage unit; Indicates the first The energy storage unit in the preset future time period The state of charge value at each moment; Indicates the first The energy storage unit in the preset future time period The state of charge value at time n, when hour, For the first The state of charge value of each energy storage unit at the current moment; Indicates the first The energy storage unit in the preset future time period The state of charge value at each moment; It represents a time interval, that is, the duration between two adjacent moments; Indicates the preset efficiency coefficient; Indicates the first The rated capacity of each energy storage unit; Indicates the number of moments within a preset future time period; Indicates the number of energy storage units;

[0028] The constraints of the power grid system include state-of-charge constraints, power constraints, and power constraints of units to be decommissioned, wherein the state-of-charge constraints are: Power constraint is The power constraint of the energy storage unit to be decommissioned is ,in, Indicates the lower limit of the preset safety range; Indicates the upper limit of the preset safety range; Indicates the first Maximum charging capacity of each energy storage unit; Indicates the first Maximum discharge capacity of each energy storage unit; Indicates the first The energy storage unit to be decommissioned within a preset future time period. Decision variables at each moment.

[0029] Furthermore, if the first If each energy storage unit is a pre-exit energy storage unit, then the range of the preset adjustment weight is: If the first If an energy storage unit is not a pre-exit energy storage unit, then the range of the preset adjustment weight is: .

[0030] Furthermore, obtaining the optimal power command value for each energy storage unit at the current moment includes:

[0031] Based on the constraints, the optimization function is solved, and the values ​​of the independent variables corresponding to the minimum value of the optimization function are used as the optimized power command value of each energy storage unit at each moment within a preset future time period.

[0032] The optimized power command value of each energy storage unit at the first moment within a preset future time period is taken as the optimal power command value of each energy storage unit at the current moment.

[0033] The present invention has the following beneficial effects:

[0034] This invention first predicts the state of charge (SOC) of the target energy storage unit in the near future and then identifies those SOCs that are not within the normal range and are pre-exited. Subsequently, the power command for these pre-exit units can be smoothly designed to avoid controlling the charging and discharging power of the energy storage units with a fixed adjustment ratio, which could lead to secondary disturbances in the power grid system. This makes the grid frequency recovery process more stable, significantly improving grid security and power quality. Then, through the constructed optimization function and constraints, the power command for each energy storage unit is further predicted and optimized to ensure the grid's stability. While stabilizing the frequency, it reduces the impact on each energy storage unit, especially the pre-exit energy storage unit, and avoids overcharging and discharging phenomena as well as secondary disturbances in the power grid system. This allows the energy storage unit to change from the traditional passive forced exit to an active predictive smooth transition. Under the premise that the total power output strictly meets the grid frequency regulation requirements, the power among the energy storage units is redistributed in advance and smoothly. This allows the pre-exit energy storage unit that is about to exceed the limit to naturally reduce its output until it safely exits, while other energy storage units naturally increase their output to make up for the gap. This makes the power coordination effect of each energy storage unit better during the grid frequency regulation process. Attached Figure Description

[0035] To more clearly illustrate the technical solutions and advantages in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0036] Figure 1 This is a flowchart of a power coordination control method for an energy storage inverter participating in grid frequency regulation, provided as an embodiment of the present invention. Detailed Implementation

[0037] To further illustrate the technical means and effects adopted by the present invention to achieve its intended purpose, the following, in conjunction with the accompanying drawings and preferred embodiments, details the specific implementation, structure, features, and effects of a power coordination control method for energy storage inverters participating in grid frequency regulation according to the present invention. In the following description, different "one embodiment" or "another embodiment" do not necessarily refer to the same embodiment. Furthermore, specific features, structures, or characteristics in one or more embodiments can be combined in any suitable form.

[0038] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0039] The following description, in conjunction with the accompanying drawings, details a specific scheme for a power coordination control method for energy storage inverters participating in grid frequency regulation provided by the present invention.

[0040] Please see Figure 1 The diagram illustrates a power coordination control method for an energy storage inverter participating in grid frequency regulation, according to an embodiment of the present invention. The method includes:

[0041] Step S1: Real-time acquisition of the state of charge value of each energy storage unit in the power grid system and the power command value received by each energy storage unit.

[0042] The power grid system serves a wide range of users, including residential, industrial, and infrastructure electricity. When large factories or other facilities suddenly experience a surge in power consumption or power outages, the power grid system may experience significant power deficits or surpluses. This can cause the grid frequency to drop or rise rapidly, reducing its stability. To ensure real-time grid frequency stability, energy storage unit clusters are typically deployed within the power grid system. Each energy storage unit is interconnected with the grid system via an energy storage inverter. When the grid frequency fluctuates, the grid system issues a power command. Upon receiving the power command, the energy storage inverter connected to the energy storage unit controls the charging and discharging of the energy storage unit with the corresponding power, thereby ensuring grid frequency stability.

[0043] Energy storage unit clusters are typically equipped with an Energy Management System (EMS) to monitor the status of the energy storage units and receive instructions from the power grid. Therefore, in this embodiment of the invention, the state of charge (SOC) value of each energy storage unit in the power grid and the power command value distributed to each energy storage unit are first collected in real time through the EMS. The SOC value reflects the energy status of the energy storage unit and is presented as a percentage. The power command value is the instruction value sent by the power grid to each energy storage unit to control the charging and discharging power of the energy storage unit. The power command value can be positive or negative. When the power command value is greater than 0, it indicates that the energy storage unit needs to discharge to the power grid at a corresponding power. When the power command value is less than 0, it indicates that the energy storage unit needs to charge to the power grid at a corresponding power to maintain the stability of the power grid frequency. In one embodiment of the invention, the data acquisition frequency is set to 1Hz, that is, data is collected once every 1 second. The data acquisition frequency can also be set by the implementer according to the specific implementation scenario, and is not limited here.

[0044] Step S2: Select any energy storage unit as the target energy storage unit. Based on the target energy storage unit's state of charge (SOC) value at the current moment and the received power command value, predict the predicted SOC value of the target energy storage unit at each moment within a preset future time period after the current moment. Based on whether the predicted SOC value of each energy storage unit at the last moment within the preset future time period is within a preset safety range, select pre-exit energy storage units from all energy storage units. Based on the SOC value of each pre-exit energy storage unit at the current moment, obtain the estimated remaining service time of each pre-exit energy storage unit.

[0045] To protect the lifespan of energy storage units and prevent overcharging and discharging, the state of charge (SOC) of these units is typically limited. When the SOC of a unit approaches or reaches a set upper or lower limit, charging and discharging of that unit ceases. However, traditional methods control energy storage units with a fixed ratio of charging and discharging power. When a unit's SOC reaches a certain threshold, it stops operating, significantly increasing the workload on other units. This can lead to a second step or gap in frequency regulation power, causing secondary disturbances to the grid and exacerbating frequency fluctuations. Furthermore, since the SOC of different energy storage units varies at any given moment, this invention aims to more accurately coordinate the charging and discharging power of each unit. For example, firstly, any energy storage unit is analyzed, taking any energy storage unit as the target energy storage unit. Based on the target energy storage unit's state of charge (SOC) value at the current moment and the received power command value, the predicted SOC value of the target energy storage unit at each moment within a preset future time period after the current moment is predicted. Subsequently, based on the changing trend of the predicted SOC value within the preset future time period, it can be predicted and judged whether the SOC value of the target energy storage unit will exceed the set safety range in the near future. The length of the preset future time period is usually 1 to 5 minutes. In one embodiment of the present invention, the length of the preset future time period is set to 2 minutes. The specific length of the preset future time period can also be set by the implementer according to the specific implementation scenario, and is not limited here.

[0046] Preferably, in one embodiment of the present invention, the method for obtaining the predicted state of charge value of the target energy storage unit at each time point within a preset future time period after the current time specifically includes:

[0047] In this embodiment of the invention, when predicting the state of charge (SOC) of a target energy storage unit within a preset future time period, it is based on the assumption that the power command value received by the target energy storage unit remains unchanged in a short period of time. That is, it is assumed that the power command value received by the target energy storage unit at each moment within the preset future time period is equal to the power command value at the current moment. Therefore, the product of the power command value received by the target energy storage unit at the current moment, the duration between each moment within the preset future time period and the current moment, and the preset efficiency coefficient can be used as the numerator, and the rated capacity of the target energy storage unit can be used as the denominator. The negative of the ratio is used as the change in SOC of the target energy storage unit at each moment within the preset future time period. Since this embodiment of the invention stipulates that when the power command value is greater than 0, the energy storage unit needs to discharge, and the SOC of the energy storage unit will decrease after discharge, the negative of the ratio is used as the change in SOC of the target energy storage unit at each moment within the preset future time period. When the change in SOC is less than 0, it indicates that the SOC of the energy storage unit will decrease; conversely, when it is greater than 0, it indicates that the SOC of the energy storage unit will increase.

[0048] Then, the sum of the target energy storage unit's state of charge value at the current moment and the change in state of charge of the target energy storage unit at each moment within the preset future time period is used as the predicted state of charge value of the target energy storage unit at each moment within the preset future time period.

[0049] As an example, in one embodiment of the present invention, the expression for the predicted state of charge value of the target energy storage unit at each time point within a preset future time period can be specifically as follows:

[0050]

[0051] in, Indicates the target energy storage unit within a preset future time period. The predicted state of charge at each moment; This represents the state of charge (SOC) value of the target energy storage unit at the current moment. Indicates the number of the first time period in the future. At that moment; Indicates the current moment; Indicates the number of the first time period in the future. The duration between the previous moment and the current moment, and the unit of this value needs to be converted to hours; This represents the power command value received by the target energy storage unit at the current moment; This indicates the rated capacity of the target energy storage unit, which is a known value, and its unit is kilowatt-hour; This represents the preset efficiency coefficient, reflecting the energy utilization efficiency of the energy storage unit during charging and discharging. It is usually expressed as coulombic efficiency. Generally, the preset efficiency coefficient differs between charging and discharging. If the power command received by the target energy storage unit at the current moment is greater than 0, it indicates that the target energy storage unit needs to discharge, and the preset efficiency coefficient is set to 1. Conversely, if the power command received by the target energy storage unit at the current moment is less than 0, it indicates that the target energy storage unit needs to charge. In this case, the preset efficiency coefficient needs to be set to less than and close to 1 to account for energy losses during charging and improve calculation accuracy. The value range of the preset efficiency coefficient is typically [missing value]. In one embodiment of the present invention, the preset efficiency coefficient is set to 0.98. The preset efficiency coefficient can also be set by the implementer according to the specific implementation scenario, and is not limited here. Indicates the target energy storage unit within a preset future time period. The change in state of charge at each moment.

[0052] The predicted state of charge value of each energy storage unit at each moment within a preset future time period can be obtained using the same method described above.

[0053] Traditional methods of controlling energy storage units with a fixed ratio of charging and discharging power will cause some units to stop operating once their state of charge exceeds a safe range. This significantly increases the workload of other energy storage units and consequently increases grid frequency instability. Therefore, this invention identifies pre-exit energy storage units based on whether their predicted state of charge value at the last moment of a preset future time period falls within a preset safe range. Subsequently, for these pre-exit units, the remaining service time can be accurately predicted, and the power commands received by each unit, especially the pre-exit units, can be optimized. This allows for a smooth and early redistribution of power among the energy storage units, ensuring that the total power output strictly meets grid frequency regulation requirements. This enables pre-exit units that are about to exceed their limits to naturally reduce their output until they safely exit, while other units naturally increase their output to fill the gap. In one embodiment of this invention, the preset safe range is set as follows: Wherein, 0.2 represents the lower limit of the state of charge (SOC). When the SOC of the energy storage unit during discharge is less than the lower limit, discharge needs to be stopped. 0.8 represents the upper limit of the SOC. When the SOC of the energy storage unit during charging is greater than the upper limit, charging needs to be stopped. In other embodiments of the present invention, the preset safety range can also be set to... The range is not limited here.

[0054] Preferably, in one embodiment of the present invention, the method for obtaining the pre-exit energy storage unit specifically includes:

[0055] Regardless of whether it is charging or discharging an energy storage unit, if the state of charge of an energy storage unit at the last moment of a preset future period is not within the preset safe range, it means that the state of charge of the energy storage unit will reach the condition of stopping operation in a short period of time in the future. Therefore, if the predicted state of charge value of the target energy storage unit at the last moment of the preset future period is not within the preset safe range, the target energy storage unit can be marked as a pre-exit energy storage unit. The same method described above can be used to determine whether each energy storage unit is a pre-exit energy storage unit.

[0056] Since the pre-exit energy storage units will cease charging and discharging services in the near future, this embodiment of the invention also needs to obtain the estimated remaining service time of each pre-exit energy storage unit based on its current state of charge value. Subsequently, an optimization function and its constraints for the power grid system can be constructed based on the estimated remaining service time of the pre-exit energy storage units, thereby achieving smooth processing of the charging and discharging power of each energy storage unit, especially the pre-exit energy storage units, and thus avoiding secondary disturbances in the power grid frequency caused by the cessation of operation of the pre-exit energy storage units.

[0057] Preferably, in one embodiment of the present invention, the method for obtaining the estimated remaining service time of each pre-exit energy storage unit specifically includes:

[0058] If any pre-exit unit is taken as the target pre-exit unit, and the power command value received by the target pre-exit unit at the current time is greater than 0, it means that the target pre-exit unit needs to discharge. Then, based on the difference between the state of charge value of the target pre-exit unit at the current time and the lower limit of the preset safety range, the power command value received by the target pre-exit unit at the current time, the rated capacity of the target pre-exit unit and the preset efficiency coefficient, the estimated remaining service time of the target pre-exit unit is obtained.

[0059] If the power command value received by the target pre-exit unit at the current moment is less than 0, it means that the target pre-exit unit needs to be charged. Then, based on the difference between the state of charge value of the target pre-exit unit at the current moment and the upper limit of the preset safety range, the power command value received by the target pre-exit unit at the current moment, the rated capacity of the target pre-exit unit and the preset efficiency coefficient, the estimated remaining service time of the target pre-exit unit is obtained.

[0060] Preferably, in one embodiment of the present invention, the method for obtaining the estimated remaining service time of each pre-exit energy storage unit further includes:

[0061] Based on the calculation formula for the estimated remaining service time, the estimated remaining service time of the target pre-exit unit is obtained, whereby the calculation formula for the estimated remaining service time is:

[0062]

[0063] in, Indicates the estimated remaining service time of the target pre-exit unit; This represents the state of charge value of the target pre-exit unit at the current moment; Indicates the lower limit of the preset safety range; Indicates the upper limit of the preset safety range; Indicates the rated capacity of the target pre-exit unit; Indicates the preset efficiency coefficient; This represents the power command value received by the target pre-exit unit at the current moment.

[0064] The estimated remaining service time for each pre-exit unit can be obtained using the same method described above.

[0065] Step S3: Based on the power command value and state of charge value of each energy storage unit at the current moment, and the expected remaining service time of each energy storage unit to be decommissioned, construct the optimization function and constraints of the power grid system; based on the optimization function and constraints, obtain the optimal power command value of each energy storage unit at the current moment.

[0066] Since there are multiple pre-exit energy storage units in the power grid system, if the charging and discharging power of the energy storage units is controlled by a fixed ratio in the traditional way, the workload of other energy storage units will increase when the pre-exit energy storage units stop working, which will make it easier to cause secondary disturbances in the power grid frequency. Therefore, the embodiments of the present invention construct the optimization function and constraints of the power grid system based on the power command value and state of charge value of each energy storage unit at the current moment, as well as the expected remaining service time of each pre-exit energy storage unit. Subsequently, the power command received by each energy storage unit, especially the pre-exit energy storage unit, can be redistributed in combination with the optimization function and constraints, so that the pre-exit energy storage unit that is about to exceed the limit will naturally and smoothly reduce its output until it safely exits, while other energy storage units will naturally and smoothly increase their output to make up for the gap.

[0067] Preferably, in one embodiment of the present invention, the method for obtaining the optimization function and constraints of the power grid system specifically includes:

[0068] First, we construct the decision variables for each energy storage unit at each moment in a preset future time period. The decision variables are in the form of: ,in, This represents the decision variable for the first energy storage unit at the first moment within a preset future time period. This represents the decision variable for the first energy storage unit at the second moment within a preset future time period. Let represent the decision variable of the m-th energy storage unit at the n-th time within a preset future time period. The decision variable is the power command that the subsequent optimization function needs to solve for, which is the power command that is redistributed to each energy storage unit.

[0069] Then, the optimization function is constructed, where the optimization function is:

[0070]

[0071]

[0072] in, Represents the optimization function of the power grid system; and They represent the first The energy storage unit in the preset future time period The moment and the The decision variable at time t, i.e., the independent variable of the optimization function, when hour, For the first The power command value of the energy storage unit at the current moment, and the preset power command value for the next time period. The moment and the Each moment is two adjacent moments; Indicates the first The power command value received by each energy storage unit at the current moment; Indicates the first Preset adjustment weights for each energy storage unit; Indicates the first The energy storage unit in the preset future time period The state of charge value at each moment; Indicates the first The energy storage unit in the preset future time period The state of charge value at time n, when hour, For the first The state of charge value of each energy storage unit at the current moment; Indicates the first The energy storage unit in the preset future time period The state of charge value at each moment; This represents a time interval, that is, the duration between two adjacent moments, and its unit needs to be converted to hours; Indicates the preset efficiency coefficient; Indicates the first The rated capacity of each energy storage unit; Indicates the number of moments within a preset future time period; This indicates the number of energy storage units.

[0073] The constraints of the power grid system include state-of-charge constraints, power constraints, and power constraints of units to be decommissioned. Among them, the state-of-charge constraints are: Power constraint is The power constraint of the energy storage unit to be decommissioned is ,in, Indicates the lower limit of the preset safety range; Indicates the upper limit of the preset safety range; Indicates the first Maximum charging capacity of each energy storage unit; Indicates the first The maximum discharge capacity of each energy storage unit and the maximum charge / discharge capacity of each energy storage unit are known values ​​that are greater than 0, and their values ​​are related to the performance of the energy storage unit itself. Indicates the first The energy storage unit to be decommissioned within a preset future time period. Decision variables at each moment.

[0074] It should be noted that, in order to ensure a smoother change in the power command redistributed by the pre-exit energy storage unit before it stops operating, the preset adjustment weight of the pre-exit energy storage unit needs to be significantly greater than the preset adjustment weight of the non-pre-exit energy storage unit. Therefore, if the first... If a storage unit is a pre-exit storage unit, then the range of the preset adjustment weight is: If the first If an energy storage unit is not a pre-exit energy storage unit, then the range of the preset adjustment weight is: In one embodiment of the present invention, the preset adjustment weight of the pre-exit energy storage unit is set to 10, and the preset adjustment weight of the non-pre-exit energy storage unit is set to 0.1. The preset adjustment weight can also be set by the implementer according to the specific implementation scenario, and is not limited here.

[0075] The optimization function is a standard for measuring the effectiveness of power smoothing of each energy storage unit. The smaller the value of the optimization function, the smoother the change of the decision variables of each energy storage unit in time series, and the better the coordination control effect. Therefore, based on the optimization function and constraints, the optimal power command value of each energy storage unit at the current moment can be obtained, thereby realizing the redistribution of power commands of each energy storage unit, avoiding secondary disturbances in the power grid system, and improving the effect of power coordination of each energy storage unit during power grid frequency regulation.

[0076] Preferably, in one embodiment of the present invention, the method for obtaining the optimal power command value of each energy storage unit at the current moment specifically includes:

[0077] The optimization function is solved by combining the constraints, and the value of each variable corresponding to the minimum value of the optimization function is used as the optimized power command value of each energy storage unit at each moment in the preset future time period. In the embodiments of the present invention, efficient QP solvers such as OSQP or qpOASES can be used for fast solution, which is not limited here.

[0078] Then, the optimized power command value of each energy storage unit at the first moment within the preset future time period is taken as the optimal power command value of each energy storage unit at the current moment.

[0079] After obtaining the optimal power command value of each energy storage unit at the current moment, the optimal power command value can be sent to the energy storage inverter connected to each energy storage unit. The energy storage inverter controls the charging and discharging operation of the energy storage unit at the current moment according to the received optimal power command value. In the subsequent charging and discharging process, the optimal power command value of each energy storage unit at each subsequent moment can be obtained in the same way as above, so as to realize real-time coordinated control of the charging and discharging power of each energy storage unit during the grid frequency regulation process.

[0080] It should be noted that the order of the above embodiments of the present invention is merely for descriptive purposes and does not represent the superiority or inferiority of the embodiments. The processes depicted in the accompanying drawings do not necessarily require a specific or sequential order to achieve the desired result. In some embodiments, multitasking and parallel processing are also possible or may be advantageous.

[0081] The various embodiments in this specification are described in a progressive manner. The same or similar parts between the various embodiments can be referred to each other. Each embodiment focuses on describing the differences from other embodiments.

Claims

1. A power coordination control method for energy storage inverter participating in grid frequency modulation, characterized in that, The method includes: Real-time acquisition of the state of charge value of each energy storage unit in the power grid system and the power command value received by each energy storage unit; Taking any energy storage unit as the target energy storage unit, based on the target energy storage unit's state of charge (SOC) value at the current moment and the received power command value, predict the target energy storage unit's SOC value at each moment within a preset future time period after the current moment; based on whether the predicted SOC value of each energy storage unit at the last moment within the preset future time period is within a preset safety range, select pre-exit energy storage units from all energy storage units; based on the SOC value of each pre-exit energy storage unit at the current moment, obtain the estimated remaining service time of each pre-exit energy storage unit; Based on the power command value and state of charge value of each energy storage unit at the current moment, and the expected remaining service time of each energy storage unit to be decommissioned, an optimization function and constraints for the power grid system are constructed; based on the optimization function and constraints, the optimal power command value of each energy storage unit at the current moment is obtained.

2. The power coordination control method for grid frequency modulation with energy storage inverters according to claim 1, characterized in that, The predicted state of charge (SOC) values ​​of the target energy storage unit at each time point within a preset future time period after the current time include: The product of the power command value received by the target energy storage unit at the current moment, the duration between each moment in the preset future time period and the current moment, and the preset efficiency coefficient is used as the numerator, the rated capacity of the target energy storage unit is used as the denominator, and the opposite of the ratio is used as the change in the state of charge of the target energy storage unit at each moment in the preset future time period. The sum of the state of charge value of the target energy storage unit at the current moment and the change in the state of charge of the target energy storage unit at each moment within a preset future time period is used as the predicted state of charge value of the target energy storage unit at each moment within the preset future time period.

3. The power coordination control method for energy storage inverters participating in grid frequency regulation according to claim 2, characterized in that, If the power instruction value received by the target energy storage unit at the current time is greater than 0, the preset efficiency coefficient is set to 1, and if the power instruction value received by the target energy storage unit at the current time is less than 0, the preset efficiency coefficient is in the range of .

4. The power coordination control method for energy storage inverters participating in grid frequency regulation according to claim 1, characterized in that, The process of selecting pre-retirement energy storage units from all energy storage units includes: If the predicted state of charge value of the target energy storage unit at the last moment of the preset future time period is not within the preset safety range, the target energy storage unit will be marked as a pre-exit energy storage unit.

5. The power coordination control method for energy storage inverters participating in grid frequency regulation according to claim 1, characterized in that, The preset security range is: .

6. The power coordination control method for energy storage inverters participating in grid frequency regulation according to claim 1, characterized in that, The process of obtaining the estimated remaining service time for each pre-exit energy storage unit includes: If any pre-exit unit is taken as the target pre-exit unit, and the power command value received by the target pre-exit unit at the current time is greater than 0, then the expected remaining service time of the target pre-exit unit is obtained based on the difference between the state of charge value of the target pre-exit unit at the current time and the lower limit of the preset safety range, the power command value received by the target pre-exit unit at the current time, the rated capacity of the target pre-exit unit and the preset efficiency coefficient. If the power command value received by the target pre-exit unit at the current moment is less than 0, the estimated remaining service time of the target pre-exit unit is obtained based on the difference between the state of charge value of the target pre-exit unit at the current moment and the upper limit of the preset safety range, the power command value received by the target pre-exit unit at the current moment, the rated capacity of the target pre-exit unit, and the preset efficiency coefficient.

7. The power coordination control method for an energy storage inverter participating in grid frequency regulation according to claim 6, characterized in that, The estimated remaining service time of the target pre-exit unit includes: Based on the calculation formula for the estimated remaining service time, the estimated remaining service time of the target pre-exit unit is obtained. The calculation formula for the estimated remaining service time is as follows: in, Indicates the estimated remaining service time of the target pre-exit unit; This represents the state of charge value of the target pre-exit unit at the current moment; Indicates the lower limit of the preset safety range; Indicates the upper limit of the preset safety range; Indicates the rated capacity of the target pre-exit unit; This indicates the preset efficiency coefficient; This represents the power command value received by the target pre-exit unit at the current moment.

8. The power coordination control method for energy storage inverters participating in grid frequency regulation according to claim 1, characterized in that, The optimization function and constraints for constructing the power grid system include: The optimization function is: in, Represents the optimization function of the power grid system; and They represent the first The energy storage unit in the preset future time period The moment and the The decision variable at time t, i.e., the independent variable of the optimization function, when hour, For the first The power command value of the energy storage unit at the current moment, and the preset power command value for the next time period. The moment and the Each moment is two adjacent moments; Indicates the first The power command value received by each energy storage unit at the current moment; Indicates the first Preset adjustment weights for each energy storage unit; Indicates the first The energy storage unit in the preset future time period The state of charge value at each moment; Indicates the first The energy storage unit in the preset future time period The state of charge value at time n, when hour, For the first The state of charge value of each energy storage unit at the current moment; Indicates the first The energy storage unit in the preset future time period The state of charge value at each moment; It represents a time interval, that is, the duration between two adjacent moments; This indicates the preset efficiency coefficient; Indicates the first The rated capacity of each energy storage unit; Indicates the number of moments within a preset future time period; Indicates the number of energy storage units; The constraints of the power grid system include state-of-charge constraints, power constraints, and power constraints of units to be decommissioned, wherein the state-of-charge constraints are: Power constraint is The power constraint of the energy storage unit to be decommissioned is ,in, Indicates the lower limit of the preset safety range; Indicates the upper limit of the preset safety range; Indicates the first Maximum charging capacity of each energy storage unit; Indicates the first Maximum discharge capacity of each energy storage unit; Indicates the first The energy storage unit to be decommissioned within a preset future time period. Decision variables at each moment.

9. A power coordination control method for an energy storage inverter participating in grid frequency regulation according to claim 8, characterized in that, If the first If each energy storage unit is a pre-exit energy storage unit, then the range of the preset adjustment weight is: If the first If an energy storage unit is not a pre-exit energy storage unit, then the range of the preset adjustment weight is: .

10. A power coordination control method for an energy storage inverter participating in grid frequency regulation according to claim 1, characterized in that, Obtaining the optimal power command value for each energy storage unit at the current moment includes: Based on the constraints, the optimization function is solved, and the values ​​of the independent variables corresponding to the minimum value of the optimization function are used as the optimized power command value of each energy storage unit at each moment within a preset future time period. The optimized power command value of each energy storage unit at the first moment within a preset future time period is taken as the optimal power command value of each energy storage unit at the current moment.

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