A Charging and Discharging Cycle Control Method and System for Energy Storage Devices in a Wind-Storage Integrated System

Abstract

The present invention discloses a charge-discharge cycle control method and system for an energy storage device in a wind-storage combined system, including: constructing an output tracking ability model with the minimum difference between the actual output of wind power and the expected output of wind power as the objective function; determining different degrees of charge-discharge cycles according to the maximum discharge depth and the relative discharge depth of the charge-discharge cycle of the energy storage device, equivalenting different degrees of charge-discharge cycles to the complete cycle times under the rated discharge depth, and constructing a charge-discharge cycle control constraint considering partial charge-discharge cycles by limiting the equivalent cycle times within a period; linearizing the output tracking ability model and the charge-discharge cycle control constraint, and obtaining the optimal output plan of the energy storage device according to the linearly transformed output tracking ability model and the charge-discharge cycle control constraint. While ensuring the life of the energy storage, it provides an energy storage operation plan that maximizes the auxiliary role of the energy storage and improves the output tracking ability of the wind-storage combined system.

Description

Technical Field

[0001] The present invention relates to the technical field of wind power generation control, and particularly to a method and system for controlling the charge and discharge cycle of an energy storage device in a wind-storage combined system. Background Art

[0002] The statements in this part merely provide background technical information related to the present invention and do not necessarily constitute prior art.

[0003] Due to the inherent randomness, volatility, and intermittency of wind energy, it is difficult to uniformly plan and dispatch wind power generation. Its large-scale grid connection may cause problems such as two-way power flow in the network and node voltage fluctuations, further affecting power quality and system security. The battery energy storage device cooperates with wind power generation, which can suppress the power fluctuation of wind power output and improve the system controllability. The wind-storage combined system can improve the utilization rate of wind energy, reduce the phenomenon of abandoned wind, improve the overall dispatchability of the system, and promote the grid connection of wind farms and their participation in market competition. Since the cost of the energy storage device itself is high, applying charge and discharge cycle control to the energy storage device aims to extend the working life of the energy storage device and minimize additional replacement and maintenance costs as much as possible, so that while the energy storage device assists in improving the overall output tracking ability of the system, it can ensure the normal working ability within the designed service life.

[0004] Currently, most of the existing control methods for energy storage devices in wind-storage combined systems only consider the overall benefits of the system, such as maximizing the overall consumption capacity of the system, maximizing the economic benefits of the system, etc., and rarely directly control the charge and discharge cycle process of energy storage, or only add control rules based on experience.

[0005] Among the existing charge and discharge cycle control methods for energy storage devices, using an approximate model is the main way to consider the impact of charge and discharge cycles on life. For example, according to the charge-discharge depth and cycle life curve of energy storage, a relationship function between cost and the two is established, and a battery life cost item related to the charge-discharge depth and daily cycle times is added to the objective function; or different charge and discharge cycles are equivalent to the cycle times under the rated charge-discharge depth, and the total equivalent cycle times of each period are directly restricted through constraints.

[0006] The charge and discharge cycle mode of the energy storage device has a significant impact on the life of the energy storage device. Frequent and deep charge and discharge will accelerate the attenuation of the energy storage capacity. In a wind-storage combined system, due to the strong randomness and volatility of wind energy, it is often difficult to track the expected output curve. The energy storage device usually shows fast charge and discharge, and frequent switching of charge and discharge states, and often cannot experience a complete charge and discharge cycle process. Corresponding to the complete cycle of the traditional energy storage device that is charged to the upper limit and then discharged, the cycle process of switching the charge and discharge state without waiting for the energy storage device to be charged to the upper limit is defined as a partial cycle.

[0007] The above technologies have the following problems in this scenario:

[0008] 1) When the direct charge-discharge cycle control is not considered, although the charge-discharge plan that maximizes the overall benefit of the system can maximize the system's output tracking ability, it will cause the premature scrapping of energy storage devices, increasing additional maintenance and replacement costs.

[0009] 2) The experience-based control strategy can maintain the energy storage life to a certain extent, but the adjustment action lags, and the overall system output tracking ability is also poor.

[0010] 3) The energy storage charge-discharge cycle control model based on the depth of discharge only considers the influence of the maximum depth of discharge in each cycle. In the scenario of a wind-storage integrated system, there are a large number of partial cycles in the energy storage device. Considering the maximum depth of discharge cannot distinguish between complete cycles and partial cycles, and the equivalent life loss will still be calculated according to one complete cycle for partial cycles. Therefore, it will limit the role of the energy storage device, affect the system's output tracking ability, and increase system wind curtailment. Summary of the Invention

[0011] To solve the above problems, the present invention proposes a method and system for controlling the charge-discharge cycle of an energy storage device in a wind-storage integrated system. By considering the maximum depth of discharge and the relative depth of discharge in each charge-discharge cycle of the energy storage device, the charge-discharge cycle process of the energy storage is modeled to effectively control the life loss of the energy storage device. While ensuring the energy storage life, an energy storage operation plan that maximizes the auxiliary role of the energy storage is provided, improving the output tracking ability of the wind-storage integrated system.

[0012] To achieve the above object, the present invention adopts the following technical solutions:

[0013] In the first aspect, the present invention provides a method for controlling the charge-discharge cycle of an energy storage device in a wind-storage integrated system, including:

[0014] Construct an output tracking ability model with the minimum difference between the actual wind power output and the expected wind power output as the objective function;

[0015] Determine different degrees of charge-discharge cycles according to the maximum depth of discharge and the relative depth of discharge of the energy storage device's charge-discharge cycle, equivalent different degrees of charge-discharge cycles to the number of complete cycles under the rated depth of discharge, and construct an energy storage cycle control constraint condition considering partial charge-discharge cycles by restricting the number of equivalent cycles within a period;

[0016] Linearize the output tracking ability model and the energy storage cycle control constraint condition, and obtain the optimal output plan of the energy storage device according to the linearly transformed output tracking ability model and the energy storage cycle control constraint condition.

[0017] As an alternative embodiment, the energy storage cycle control constraint conditions include the maximum discharge depth of each cycle of the energy storage device, the relative discharge depth of each charge-discharge cycle, and the total equivalent cycle number within a period.

[0018] As an alternative embodiment, the energy storage cycle control constraint conditions are specifically:

[0019]

[0020] ts(t) + tf(t) ≤ 1

[0021]

[0022]

[0023]

[0024]

[0025]

[0026]

[0027] delta_soc(t) = (soca(t) - dod2(t)) × tf(t)

[0028] dod_soca(t) = soca(t) × tf(t)

[0029]

[0030] Wherein, yin(t) and yout(t) are 0-1 variables indicating the charge-discharge state of the energy storage. When the energy storage is charging at time t, yin(t) = 1; when discharging, yout(t) = 1. ts(t) and tf(t) are 0-1 variables indicating the start and end times of the energy storage charging. The start time of charging ts(t) = 1, and the end time of charging tf(t) = 1; soc is the state of charge variable of the energy storage device; dod is the maximum discharge depth variable of the energy storage device, which is equal to the maximum discharge depth of this cycle at the start time of charging and 0 at other times; dod2 is the discharge depth variable of the energy storage device at the end time of charging, which is equal to the discharge depth at the current time at the end time of charging and 0 at other times; the intermediate variable soca is equal to the maximum discharge depth at the start time of charging and is equal to the previous moment at other times; the intermediate variable delta_soc is equal to the relative discharge depth of this cycle at the end time of discharging and 0 at other times; the intermediate variable dod_soca(t) is equal to the maximum discharge depth of this cycle at the end time of discharging and 0 at other times; N cycleis the expected number of equivalent cycles within a period; the function g is a non-linear function of the maximum depth of discharge and the relative depth of discharge; dod(0), dod2(0), and soca(0) are the values of the above variables at the initial moment of the period.

[0031] As an alternative implementation, during the linearization process, the maximum depth of discharge and the relative depth of discharge are transformed:

[0032]

[0033]

[0034]

[0035]

[0036]

[0037]

[0038] where y d and y d2 are both 0-1 variables to assist in piecewise linearization; dodn(t, n1) is the maximum depth of discharge piecewise variable for the n1 segment at time t; and are the upper and lower bounds of the depth of discharge segments respectively; deltan(t, n2) is the relative depth of discharge piecewise variable for the n2 segment at time t; and are the upper and lower bounds of the relative depth of discharge segments respectively.

[0039] As an alternative implementation, after piecewise linearizing the maximum depth of discharge and the relative depth of discharge for each charge-discharge cycle respectively, by associating with the equivalent cycle number table, the conversion of charge-discharge cycles with different degrees is carried out, that is:

[0040]

[0041] where V loss (n1, n2) is the corresponding equivalent cycle number in the table of the maximum depth of discharge for the n1 segment and the relative depth of discharge for the n2 segment; N cycle is the expected number of equivalent cycles within a period.

[0042] As an alternative implementation, the output tracking ability model further includes the output balance constraint of the wind-storage combined system:

[0043]

[0044] where is the energy storage discharge power value at time t, is the energy storage charging power value at time t; is the predicted wind power output at time t, is the expected wind power output at time t, is the difference between the actual wind power output and the expected wind power output.

[0045] As an alternative implementation, the output tracking ability model further includes the relationship constraint between the state of charge of the energy storage device and the charge-discharge power, and the range constraint of the state of charge and the charge-discharge power.

[0046] In a second aspect, the present invention provides a charge-discharge cycle control system for an energy storage device in a wind-storage combined system, including:

[0047] A model construction module, configured to construct an output tracking ability model with the minimum difference between the actual wind power output and the expected wind power output as the objective function;

[0048] A constraint construction module, configured to determine different degrees of charge-discharge cycles according to the maximum discharge depth and the relative discharge depth of the charge-discharge cycle of the energy storage device, equivalent the different degrees of charge-discharge cycles to the number of complete cycles under the rated discharge depth, and construct the energy storage cycle control constraint conditions considering partial charge-discharge cycles by restricting the number of equivalent cycles within a period;

[0049] A linearization and solution module, configured to linearize the output tracking ability model and the energy storage cycle control constraint conditions, and obtain the optimal output plan of the energy storage device according to the linearly transformed output tracking ability model and the energy storage cycle control constraint conditions.

[0050] In a third aspect, the present invention provides an electronic device, including a memory, a processor, and computer instructions stored on the memory and running on the processor. When the computer instructions are run by the processor, the method described in the first aspect is completed.

[0051] In a fourth aspect, the present invention provides a computer-readable storage medium for storing computer instructions. When the computer instructions are executed by a processor, the method described in the first aspect is completed.

[0052] Compared with the prior art, the beneficial effects of the present invention are:

[0053] The present invention provides a charge-discharge cycle control method and system for an energy storage device in a wind-storage combined system. By considering the maximum discharge depth and relative discharge depth of each charge-discharge cycle of the energy storage device, the charge-discharge cycle process of the energy storage is modeled, effectively controlling the life loss of the energy storage device, ensuring the normal working ability of the energy storage device within the designed working life, effectively reducing the life loss caused by random charge and discharge, and reducing unnecessary maintenance and replacement costs; while ensuring the life of the energy storage, a storage operation plan that maximizes the auxiliary role of the energy storage is provided, improving the output tracking ability of the wind-storage combined system.

[0054] The present invention provides a charge-discharge cycle control method and system for an energy storage device in a wind-storage combined system. By considering the maximum discharge depth and relative discharge depth of each charge-discharge cycle of the energy storage device, the charge-discharge cycle control constraints of the energy storage are established. Through the life loss caused by charge-discharge cycles of different degrees, the life loss caused by different charge-discharge cycles is correctly converted, and the output plan of the energy storage device is solved. While maximizing the output tracking ability of the system, the normal working ability of the energy storage device within the designed working life is ensured.

[0055] The present invention provides a charge-discharge cycle control method and system for an energy storage device in a wind-storage combined system. Considering partial charge-discharge cycles of the energy storage device, by equivalenting charge-discharge cycles of different degrees to the total number of full cycles at the rated discharge depth, and by restricting the total number of equivalent cycles within a period, the charge-discharge cycle control of the energy storage device is realized.

[0056] The present invention provides a charge-discharge cycle control method and system for an energy storage device in a wind-storage combined system. The charge-discharge cycle control constraints of the energy storage considering partial charge-discharge cycles are constructed, and the output tracking ability model and constraints are linearly processed. The output plan of the energy storage is obtained through the overall solution of the optimal output tracking model of the wind-storage combined system, taking into account both the life of the energy storage device and the output tracking ability of the system.

[0057] Advantages of additional aspects of the present invention will be given in part in the following description, will become apparent in part from the following description, or will be understood through the practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0058] The specification drawings constituting a part of the present invention are used to provide a further understanding of the present invention. The schematic embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention.

[0059] Figure 1 It is a flowchart of the charge-discharge cycle control method for the energy storage device in the wind-storage combined system provided in Embodiment 1 of the present invention;

[0060] Figure 2 It is a schematic diagram of the expected output curve and predicted output curve of the wind-storage combined system provided in Embodiment 1 of the present invention;

[0061] Figure 3 Schematic diagram of the expected output curve of the wind-storage integrated system provided in Embodiment 1 of the present invention and the actual optimized output result curve of the method of the present invention;

[0062] Figure 4(a)-4(b) Schematic diagram of the optimized result of the energy storage device state provided in Embodiment 1 of the present invention;

[0063] Figure 5 Schematic diagram of the expected output and actual output curves of the wind power integrated system without considering the life loss of the energy storage device provided in Embodiment 1 of the present invention;

[0064] Figure 6(a)-6(b) Schematic diagram of the optimized result of the energy storage device state without considering the charge and discharge cycle control of the energy storage device provided in Embodiment 1 of the present invention;

[0065] Figure 7(a)-7(b) Schematic diagram of the optimized result of the energy storage device state of the traditional method only considering the maximum discharge depth provided in Embodiment 1 of the present invention. Detailed implementation manners

[0066] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0067] It should be noted that the following detailed description is exemplary and is intended to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the technical field to which the present invention belongs.

[0068] It should be noted that the terms used herein are only for describing specific implementation manners and are not intended to limit the exemplary embodiments according to the present invention. As used herein, unless the context clearly indicates otherwise, the singular forms are also intended to include the plural forms. In addition, it should be understood that the terms "comprising" and "having" and any variations thereof 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 clearly listed, but may include other steps or units not clearly listed or inherent to these processes, methods, products or devices.

[0069] In the case of no conflict, the embodiments in the present invention and the features in the embodiments can be combined with each other.

[0070] Embodiment 1

[0071] As Figure 1As shown in the figure, this embodiment proposes a charge-discharge cycle control method for the energy storage device of a wind-storage combined system that considers partial cycle effects based on the maximum discharge depth and relative discharge depth. By considering the maximum discharge depth and relative discharge depth of each charge-discharge cycle of the energy storage device, reasonable energy storage cycle control constraint conditions are established. According to the life losses caused by different degrees of charge-discharge cycles, the life losses caused by different charge-discharge cycles are correctly converted. Relying on the operation research optimization solution technology to solve the output plan of the energy storage device, the real-time performance and optimality of the solution are ensured. While maximizing the system output tracking ability, the normal working ability of the energy storage device within the designed working life is ensured.

[0072] Specifically, it includes the following steps:

[0073] Taking the minimum difference between the actual output of wind power and the expected output of wind power as the objective function, an output tracking ability model is constructed;

[0074] According to the maximum discharge depth and relative discharge depth of the charge-discharge cycle of the energy storage device, different degrees of charge-discharge cycles are determined. The different degrees of charge-discharge cycles are equivalent to the complete cycle times under the rated discharge depth. By restricting the equivalent cycle times within a period, the energy storage cycle control constraint conditions considering partial charge-discharge cycles are constructed;

[0075] Linearize the output tracking ability model and the energy storage cycle control constraint conditions. According to the linearly transformed output tracking ability model and the energy storage cycle control constraint conditions, the optimal output plan of the energy storage device is obtained.

[0076] In this embodiment, through a large number of repeated experimental tests on the energy storage device samples, a table of the maximum discharge depth, relative discharge depth, and equivalent cycle times of partial charge-discharge cycles is obtained, which is used as the basis for subsequent life loss conversion.

[0077] The equivalent cycle times table distinguishes different degrees of partial charge-discharge cycles according to the maximum discharge depth and relative discharge depth, and equivalent all different degrees of partial charge-discharge cycles of the energy storage device to the complete cycle times under the rated discharge depth; by restricting the total number of equivalent cycles within a period, the charge-discharge cycle control of the energy storage device is realized.

[0078] In this embodiment, the expected output of wind power in the wind-storage combined system is obtained and the predicted output of wind power The purpose of the energy storage device to assist in regulation is to make the final wind power output of the wind-storage combined system as consistent as possible with the expected output of wind power. Therefore, the action decision will be made according to the difference between the predicted output of wind power and the expected output of wind power.

[0079] In this embodiment, with the minimum difference between the actual wind power output and the expected wind power output as the objective function, an output tracking ability model of a wind-storage integrated system considering the influence of partial cycling is constructed. The ultimate goal of the output tracking ability model is to minimize the deviation between the two, that is, to maximize the overall output tracking ability of the wind-storage integrated system.

[0080] In this embodiment, the objective function is:

[0081]

[0082] Where, is the difference between the actual wind power output and the expected wind power output of the wind-storage integrated system.

[0083] In this embodiment, the constraint conditions of the output tracking ability model include:

[0084] (1) Overall output balance constraint of the wind-storage integrated system:

[0085]

[0086] Where, is the energy storage discharge power value, is the energy storage charging power value; is the predicted wind power output, is the expected wind power output and is the final output expected to be obtained.

[0087] (2) Inherent physical constraints satisfied by the energy storage device:

[0088]

[0089]

[0090] SOC min ≤soc(t)≤SOC max (5)

[0091] yin(t)+yout(t)=1(6)

[0092]

[0093]

[0094] Where, soc is the state of charge of the energy storage device, are the charging and discharging efficiencies of the energy storage device respectively, is the rated capacity of the energy storage, soc0 is the state of charge of the energy storage at the initial moment, SOC max and SOC minare the upper and lower limits of the state of charge of the energy storage device, yin and yout are 0-1 variables, which are the action quantities describing whether the energy storage device charges or discharges.

[0095] Among them, Equations (3)-(4) describe the relationship between the state of charge of the energy storage device and the charge and discharge power, and Equations (5)-(8) are the range constraints of the state of charge and the charge and discharge power.

[0096] (3) The energy storage cycle control constraints considering the influence of partial charge and discharge cycles include the maximum discharge depth of each cycle of the energy storage device, the relative discharge depth of each charge and discharge cycle, and the total equivalent cycle number within the period, specifically:

[0097]

[0098]

[0099]

[0100]

[0101]

[0102]

[0103]

[0104]

[0105] delta_soc(t) = (soca(t) - dod2(t)) × tf(t) (17)

[0106] dod_soca(t) = soca(t) × tf(t) (18)

[0107]

[0108] Among them, yin(t) and yout(t) are 0-1 variables indicating the charge and discharge states of the energy storage. When the energy storage is charging at time t, yin(t) = 1; when discharging, yout(t) = 1. ts(t) and tf(t) are 0-1 variables indicating the start and end times of energy storage charging. ts(t) = 1 at the start time of charging, and tf(t) = 1 at the end time of charging; soc is the state of charge variable of the energy storage device; dod is the maximum discharge depth variable of the energy storage device, which is equal to the maximum discharge depth of this cycle at the start time of charging and 0 at other times; dod2 is the discharge depth variable of the energy storage device at the end of charging, which is equal to the discharge depth at the current time at the end of charging and 0 at other times; the intermediate variable soca is equal to the maximum discharge depth at the start time of charging and is equal to the previous time at other times. The purpose of this variable is to translate the maximum discharge depth along the time axis to the end time of charging for convenient subsequent operations; the intermediate variable delta_soc is equal to the relative discharge depth of this cycle at the end of discharging and 0 at other times; the intermediate variable dod_soca(t) is equal to the maximum discharge depth of this cycle at the end of discharging and 0 at other times; N cycle is the expected number of equivalent cycles within a period; the function g is a non-linear function of the maximum discharge depth and the relative discharge depth, which is used to convert the equivalent number of cycles. dod(0), dod2(0) and soca(0) are the values of the above variables at the initial moment of the period.

[0109] The above equations (11)-(12) represent obtaining the discharge depth dod of the energy storage device at each moment through the state of charge soc; equations (13)-(14) represent obtaining the highest state of charge dod2 of the energy storage device for each cycle; soca is an intermediate variable, which is equal to the discharge depth at the start time of charging and is equal to the previous time at other times. Equations (15)-(16) represent the maximum discharge depth for continuing each charge and discharge cycle; equations (12), (14), and (16) perform special processing on the initial moment to exclude the situation of double-counting the cycles that are connected end to end during continuous operation.

[0110] In equation (19), the function g is a non-linear function of the maximum discharge depth dod_soca(t) and the relative discharge depth delta_soc(t) / (1 - dod_soca(t)) for each charge and discharge cycle. Through this non-linear function, charge and discharge cycles of different degrees are converted into the equivalent number of full cycles at the rated discharge depth. Since the total cycle life of the energy storage device is known, by restricting the equivalent cycle life loss of each period within the expected number N cycle inside, the life loss of the energy storage device can be controlled.

[0111] In this embodiment, the output tracking ability model and the energy storage cycle control constraint conditions are linearly transformed, and the output tracking ability model is transformed into a mixed-integer linear model; specifically, it includes:

[0112] The equations (11)-(16) in the energy storage cycle control constraints are linearly transformed, and the big M method is used to transform them into linear constraints;

[0113] For the non-linear function g of the maximum discharge depth and the relative discharge depth in the energy storage cycle control constraints, the bilinear piecewise look-up table method is used for linear transformation;

[0114] The bilinear piecewise look-up table method includes:

[0115] The maximum discharge depth and the relative discharge depth are transformed:

[0116]

[0117]

[0118]

[0119]

[0120]

[0121]

[0122] where y d and y d2 are both 0-1 variables for auxiliary piecewise linearization; dodn is the maximum discharge depth piecewise variable; and are the upper and lower bounds of the discharge depth segments respectively; deltan is the relative discharge depth piecewise variable; and are the upper and lower bounds of the relative discharge depth segments respectively.

[0123] Equations (20)-(22) and equations (23)-(25) linearize the maximum discharge depth and the relative discharge depth of each cycle respectively, and the equivalent cycle number table is associated through equation (26) to realize the conversion of different degrees of charge and discharge cycles, that is:

[0124]

[0125] where V loss (n1,n2) is the corresponding equivalent cycle number in the table of the maximum discharge depth of the n1 segment and the relative discharge depth of the n2 segment; by adding a limit to the sum of the equivalent cycle numbers within a period, it is made less than the maximum equivalent cycle number N of the energy storage cycle, realizing the management of energy storage life loss.

[0126] In this embodiment, the bilinear look-up table method can simply and reliably convert the non-linearity of the model. At the same time, the equivalent cycle number table of the maximum discharge depth and the relative discharge depth has a clear physical meaning and can be simply obtained through experiments.

[0127] In this embodiment, a solver is used to solve the output tracking ability model after linear conversion to obtain the optimal output plan of the energy storage device in the wind-storage combined system.

[0128] Model simulation of this embodiment:

[0129] (1-1) Obtain the relevant parameters of the energy storage device from the device provider and repeatedly test the energy storage device sample to obtain the equivalent cycle number table of the absolute and relative discharge depths and partial cycles. The energy storage device parameters used in this embodiment are shown in Table 1, and the equivalent cycle number table obtained through experiments is shown in Table 2. The data in the table represents the equivalent life loss of the charge and discharge cycles with different relative discharge depths in different maximum discharge depth ranges. For example, when the energy storage device undergoes charge and discharge cycles with a maximum discharge depth in the range of 0.2-0.4 and a relative discharge depth in the range of 0.3-0.4, the loss caused by this cycle can be converted into 0.3 full cycles at the rated discharge depth.

[0130] Table 1 Energy storage related parameters

[0131]

[0132]

[0133] Table 2 Equivalent cycle number table

[0134]

[0135] (1-2) Obtain the predicted output and expected output of the wind power generation equipment as Figure 2 , and finally, it is necessary to minimize the error between the actual output and the expected output through the energy storage device.

[0136] (1-3) Determine the parameters of the output tracking ability model, use a solver to solve the output tracking ability model, and obtain the actual wind power output curve as Figure 3 , and the output curve of the energy storage device as Figure 4(a)-4(b) . At this time, the total error for the entire cycle is 234.45 MW. Compared with the situation where the original predicted output and the expected output do not match at all times, the error is reduced to 8 moments.

[0137] (1-4) Without considering the life loss of the energy storage device, the optimization result of the output tracking ability model is as Figure 5 , and the output of the energy storage device is asFigure 6(a)-6(b) The overall state of charge of the energy storage device changes quite dramatically, with large fluctuations. Although the total error for the entire cycle is only 208.61MW and occurs only at three moments, the equivalent life loss during the actual energy storage cycle is as high as approximately 2.83 times. The energy storage device can only operate normally for about four years, a lifespan shortened by nearly 50%.

[0138] (1-5) Compared with the commonly used energy storage device charge and discharge cycle control method that only considers the maximum discharge depth, the total error of the wind-storage combined system in the entire cycle under this method is 253.21MW, with deviations at 9 moments. Since this control method converts partial cycles into full cycles, the energy storage output plan is relatively conservative. Figure 7(a)-7(b) At this time, the overall charge state of the energy storage device changes smoothly, all partial cycles are converted as full cycles, and the energy storage device fails to play its maximum role, so the result is relatively poor.

[0139] Comparing the method of this embodiment with the method that does not consider the loss of energy storage equipment, the method of this embodiment can reliably control the charging and discharging process of the energy storage equipment, ensuring the normal working ability of the energy storage equipment during its service life; comparing the method of this embodiment with the traditional method that only considers the maximum discharge depth, this embodiment adds parameters that can be easily obtained through experiments. Table 1 and proposes a method for controlling the charging and discharging cycle of energy storage equipment that considers the influence of partial cycles overcomes the conservatism of the traditional method and improves the overall output tracking capability of the joint system. The state of charge comparison in Figure 4 Figure 6(a)-6(b) and Figure 7(a)-7(b) The optimization results of the method in this embodiment reduce the more aggressive charge and discharge cycle process of the energy storage device and extend the energy storage life; improve the charge state under the overall working state, and retain an appropriate number of partial cycles, thereby obtaining a more reasonable energy storage device cycle plan.

[0140] Example 2

[0141] This embodiment provides a charge and discharge cycle control system for energy storage equipment in a wind-storage combined system, including:

[0142] The model building module is configured to build an output tracking capability model by taking the minimum difference between the actual wind power output and the expected wind power output as the objective function;

[0143] a constraint construction module configured to determine different degrees of charge-discharge cycles based on the maximum depth of discharge and relative depth of discharge of the charge-discharge cycle of the energy storage device, equate the different degrees of charge-discharge cycles to the number of full cycles at the rated depth of discharge, and construct energy storage cycle control constraints that consider partial charge-discharge cycles by limiting the number of equivalent cycles within the cycle;

[0144] A linear and solution module, configured to linearize the output tracking ability model and the energy storage cycle control constraint conditions, and obtain the optimal output plan of the energy storage device according to the linearly transformed output tracking ability model and the energy storage cycle control constraint conditions.

[0145] It should be noted here that the above module corresponds to the steps described in Embodiment 1. The examples and application scenarios implemented by the above module and the corresponding steps are the same, but are not limited to the content disclosed in the above Embodiment 1. It should be noted that the above module, as a part of the system, can be executed in a computer system such as a set of computer-executable instructions.

[0146] In more embodiments, there is also provided:

[0147] An electronic device, including a memory, a processor, and computer instructions stored on the memory and running on the processor. When the computer instructions are run by the processor, the method described in Embodiment 1 is completed. For the sake of brevity, it will not be elaborated here.

[0148] It should be understood that in this embodiment, the processor may be a central processing unit CPU, and the processor may also be other general-purpose processors, digital signal processors DSP, application-specific integrated circuits ASIC, off-the-shelf programmable gate arrays FPGA, or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. The general-purpose processor may be a microprocessor or the processor may also be any conventional processor, etc.

[0149] The memory may include a read-only memory and a random access memory, and provide instructions and data to the processor. A part of the memory may also include a non-volatile random access memory. For example, the memory may also store information about the device type.

[0150] A computer-readable storage medium, used to store computer instructions. When the computer instructions are executed by the processor, the method described in Embodiment 1 is completed.

[0151] The method in Embodiment 1 can be directly implemented by a hardware processor, or implemented by a combination of hardware and software modules in the processor. The software module may be located in a mature storage medium in the art such as random access memory, flash memory, read-only memory, programmable read-only memory, or electrically erasable programmable memory, register, etc. This storage medium is located in the memory, and the processor reads the information in the memory and combines its hardware to complete the steps of the above method. To avoid repetition, it will not be described in detail here.

[0152] Those of ordinary skill in the art will appreciate that the units or algorithm steps of the examples described in conjunction with this embodiment can be implemented by electronic hardware or a combination of computer software and electronic hardware. Whether these functions are executed in hardware or software depends on the specific application and design constraints of the technical solution. A person skilled in the art can use different methods for each specific application to implement the described functions, but such implementation should not be considered to exceed the scope of this application.

[0153] Although the specific implementation manners of the present invention have been described above in conjunction with the accompanying drawings, it is not a limitation on the protection scope of the present invention. Those skilled in the art should understand that various modifications or deformations that can be made by those skilled in the art without creative efforts on the basis of the technical solution of the present invention are still within the protection scope of the present invention.

Claims

1. A charge-discharge cycle control method for an energy storage device in a wind-storage combined system, characterized in that, Including: Taking the minimum difference between the actual wind power output and the expected wind power output as the objective function, an output tracking ability model is constructed; According to the maximum discharge depth and the relative discharge depth of the charge and discharge cycles of the energy storage device, charge and discharge cycles of different degrees are determined. The charge and discharge cycles of different degrees are equivalent to the complete cycle times at the rated discharge depth, and by restricting the equivalent cycle times within a period, a charge and discharge cycle control constraint condition considering partial charge and discharge cycles is constructed; The output tracking ability model and the charge and discharge cycle control constraint condition are linearized. According to the output tracking ability model and the charge and discharge cycle control constraint condition after linear transformation, the optimal output plan of the energy storage device is obtained; The specific charge and discharge cycle control constraint condition is: ts(t)+tf(t)≤1 delta_soc(t)=(soca(t)-dod2(t))×tf(t) dod_soca(t)=soca(t)×tf(t) Wherein, yin(t) and yout(t) are 0-1 variables indicating the charge and discharge states of the energy storage. When the energy storage is charged at time t, yin(t)=1, and when it is discharged, yout(t)=1. ts(t) and tf(t) are 0-1 variables indicating the start and end times of the energy storage charging. The start time of charging ts(t)=1, and the end time of charging tf(t)=1; soc is the state of charge variable of the energy storage device; dod is the maximum discharge depth variable of the energy storage device, which is equal to the maximum discharge depth of this cycle at the start time of charging and 0 at other times; dod2 is the discharge depth variable at the end time of the energy storage charging, which is equal to the discharge depth at the current time at the end time of charging and 0 at other times; the intermediate variable soca is equal to the maximum discharge depth at the start time of charging and is equal to the previous time at other times; the intermediate variable delta_soc is equal to the relative discharge depth of this cycle at the end time of discharging and 0 at other times; The intermediate variable dod_soca(t) is equal to the maximum discharge depth of the current cycle at the end of discharge, and is 0 at other times; N cycle is the expected number of equivalent cycles within a period; the function g is a non-linear function of the maximum discharge depth and the relative discharge depth; dod(0), dod2(0), and soca(0) are the values of the above variables at the initial moment of the period.

2. The charge and discharge cycle control method for an energy storage device in a wind and energy storage combined system according to claim 1, wherein The charge and discharge cycle control constraint condition includes the maximum discharge depth of each cycle of the energy storage device, the relative discharge depth of each charge and discharge cycle, and the total equivalent cycle times within a period.

3. The charge and discharge cycle control method for an energy storage device in a wind and energy storage combined system according to claim 1, wherein During the linearization process, the maximum discharge depth and the relative discharge depth are transformed: where y d and y d2 are both 0-1 variables for auxiliary piecewise linearization; dodn(t,n1) is the maximum depth of discharge piecewise variable for the n1 segment at time t; and are the upper and lower bounds of the depth of discharge segments respectively; deltan(t,n2) is the relative depth of discharge piecewise variable for the n2 segment at time t; and are the upper and lower bounds of the relative depth of discharge segments respectively.

4. The charge and discharge cycle control method for an energy storage device of a wind-storage combined system according to claim 3, wherein After linearizing the maximum discharge depth and the relative discharge depth of each charge and discharge cycle, through associating with the equivalent cycle times table, the conversion of charge and discharge cycles of different degrees is carried out, that is: Among them, V loss (n1, n2) is the equivalent cycle number corresponding to the maximum discharge depth of the n1 segment and the relative discharge depth of the n2 segment in the following table; N cycle is the expected number of equivalent cycles within a period.

5. A charge and discharge cycle control method for an energy storage device of a wind and energy storage combined system according to claim 1, characterized in that, The output tracking ability model also includes the output balance constraint of the wind-storage combined system: Among them, is the energy storage discharge power value at time t, is the energy storage charging power value at time t; is the predicted wind power output at time t, is the expected wind power output at time t, is the difference between the actual wind power output and the expected wind power output.

6. A charge-discharge cycle control method for an energy storage device in a wind-storage combined system according to claim 1, characterized in that, The output tracking ability model also includes the relationship constraint between the state of charge of the energy storage device and the charge and discharge power, and the range constraint of the state of charge and the charge and discharge power.

7. A charge and discharge cycle control system for an energy storage device in a wind and energy storage combined system, which adopts a charge and discharge cycle control method for an energy storage device in a wind and energy storage combined system as described in claim 1, characterized in that, Including: A model construction module, configured to construct an output tracking ability model with the minimum difference between the actual wind power output and the expected wind power output as the objective function; A constraint construction module, configured to determine different levels of charge-discharge cycles according to the maximum discharge depth and the relative discharge depth of the charge-discharge cycles of the energy storage device, equivalent the different levels of charge-discharge cycles to the number of full cycles at the rated discharge depth, and construct the energy storage cycle control constraint conditions considering partial charge-discharge cycles by limiting the number of equivalent cycles within a period; A linearization and solution module, configured to linearize the output tracking ability model and the energy storage cycle control constraint conditions, and obtain the optimal output plan of the energy storage device according to the output tracking ability model and the energy storage cycle control constraint conditions after linear transformation; 8. An electronic device, characterized in that, It includes a memory, a processor, and computer instructions stored on the memory and running on the processor. When the computer instructions are run by the processor, the method described in any one of claims 1-6 is completed.

9. A computer-readable storage medium, characterized in that, For storing computer instructions, when the computer instructions are executed by the processor, the method described in any one of claims 1-6 is completed.

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