Frequency modulation type flow battery energy storage control method, system, equipment and medium

Abstract

The invention belongs to the field of battery energy storage, and discloses a frequency modulation type flow battery energy storage control method, system, equipment and medium, the method comprises the following steps: carrying out balance control on electrolyte flow of a flow battery energy storage module to obtain a frequency modulation type flow battery energy storage system; calculating the theoretical charge state and the open-circuit voltage of the frequency modulation type flow battery energy storage module; performing visualization processing on calculation results of the theoretical charge state and the open-circuit voltage to obtain a relation rule of the theoretical charge state and the open-circuit voltage; the actual state of charge of the frequency modulation type flow battery energy storage module is obtained by measuring the actual open-circuit voltage of the frequency modulation type flow battery energy storage module and combining the relation rule of the theoretical state of charge and the open-circuit voltage; and performing energy storage control on the frequency modulation type flow battery energy storage module according to the energy storage state of the frequency modulation type flow battery energy storage module. The independence of the unit battery module of the liquid flow energy storage system is improved, and the calculation error of the actual state of charge is reduced.

Description

Technical Field

[0001] The present invention relates to the field of battery energy storage, and in particular to a frequency modulation type liquid flow battery energy storage control method, system, equipment and medium. Background Art

[0002] With the rapid growth of new energy generation such as wind power and photovoltaic power, its volatility and uncertainty have posed challenges to the stability of the power system. In order to absorb the rapidly growing new energy, the power system needs more flexible adjustment methods. Energy storage technology can balance the intermittent and instability of new energy generation and increase the proportion and utilization rate of new energy connected to the grid. Liquid flow energy storage technology has excellent safety, long life, green and environmental protection characteristics. It is one of the first choices for large-scale energy storage technology. At present, liquid flow energy storage technology is being used more and more in power systems.

[0003] The power unit and capacity unit of the flow battery are independent of each other and have flexible configuration. The battery or battery stack is the place where the flow battery realizes the charging and discharging functions. The power unit of the flow battery system is usually composed of them in series and parallel. The capacity unit mainly refers to the energy storage medium of the flow battery, which contains active substances, supporting electrolytes and solvents. Compared with other traditional batteries (such as lead-acid batteries, lead-carbon batteries, lithium batteries, etc.), the biggest difference between flow batteries is that the power unit and capacity unit that constitute their battery system are independent of each other.

[0004] Liquid flow energy storage can provide flexible adjustment capabilities for the power grid on different time scales, and can meet the power grid's needs for primary frequency modulation (seconds), secondary frequency modulation (minutes), and tertiary frequency modulation (hours). Therefore, liquid flow energy storage is suitable as a frequency modulation power source for the power system, providing flexible adjustment capabilities for the power system.

[0005] Large-scale liquid flow energy storage systems used in power systems are usually composed of multiple unit battery energy storage modules. Each unit battery energy storage module has its own independent BMS control system (Battery Management System). In actual operation, it is difficult to coordinate multiple BMSs, and there are problems such as poor uniformity of single cells and difficulty in accurately measuring SOC inside the unit battery energy storage module, which affects the frequency regulation performance of the liquid flow battery energy storage system.

[0006] Therefore, how to provide a frequency-modulated liquid flow battery energy storage control method, system, equipment and medium is a problem that needs to be solved urgently. Summary of the invention

[0007] The embodiments of the present invention provide a frequency-modulated liquid flow battery energy storage control method, system, device and medium to solve the problems in the prior art that multiple BMSs are difficult to coordinate and unify, and that there is poor uniformity of single cells inside the unit battery energy storage module and that SOC is difficult to accurately measure.

[0008] In order to have a basic understanding of some aspects of the disclosed embodiments, a brief summary is given below. This summary is not intended to be a general review, nor is it intended to identify key / important components or to delineate the scope of protection of these embodiments. Its only purpose is to present some concepts in a simple form as a preface to the detailed description that follows.

[0009] According to a first aspect of an embodiment of the present invention, a frequency-modulated liquid flow battery energy storage control method is provided.

[0010] In one embodiment, a frequency-modulated liquid flow battery energy storage control method includes:

[0011] Based on the frequency conversion control technology, combined with the flow control measures of the electrolyte valve and the flow monitoring measures of the electrolyte flow meter, the electrolyte flow of the flow battery energy storage module is balanced controlled to obtain a frequency modulation type flow battery energy storage system, and the frequency modulation type flow battery energy storage system includes a plurality of frequency modulation type flow battery energy storage modules;

[0012] According to the state of charge equation and the open circuit voltage formula, the theoretical state of charge and open circuit voltage of the frequency-modulated liquid flow battery energy storage module are calculated; the calculation results of the theoretical state of charge and open circuit voltage are visualized to obtain the relationship between the theoretical state of charge and the open circuit voltage;

[0013] By measuring the actual open circuit voltage of the frequency modulated liquid flow battery energy storage module and combining the relationship between the theoretical state of charge and the open circuit voltage, the actual state of charge of the frequency modulated liquid flow battery energy storage module is obtained;

[0014] The controller is used to integrate the electrolyte flow, actual state of charge, temperature and health status of the frequency-modulated liquid flow battery energy storage module to obtain the energy storage state of the frequency-modulated liquid flow battery energy storage module; the energy storage of the frequency-modulated liquid flow battery energy storage module is controlled according to the energy storage state of the frequency-modulated liquid flow battery energy storage module.

[0015] In one embodiment, based on the frequency conversion control technology, combined with the flow control measures of the electrolyte valve and the flow monitoring measures of the electrolyte flow meter, the electrolyte flow of the flow battery energy storage module is balanced controlled, including:

[0016] The electrolyte flow rate of each stack positive electrode and negative electrode in the liquid flow battery energy storage module is controlled by the electrolyte valve;

[0017] The electrolyte flow rate of each stack positive electrode and negative electrode in the flow battery energy storage module is measured by an electrolyte flow meter;

[0018] The frequency conversion control technology is adopted to perform frequency conversion control on the positive electrode electrolyte pump and the negative electrode electrolyte pump, so that the electrolyte flow rate flowing inside each fuel cell stack is the same, and the positive electrode electrolyte flow rate entering each fuel cell stack is the same, and the negative electrode electrolyte flow rate entering each fuel cell stack is the same.

[0019] In one embodiment, frequency conversion control of the positive electrolyte pump and the negative electrolyte pump includes:

[0020] A positive electrode electrolyte pump is used to drive the positive electrode electrolyte through the battery stack and finally flows back to the positive electrode storage tank; a negative electrode electrolyte pump is used to drive the negative electrode electrolyte through the battery stack and finally flows back to the negative electrode storage tank;

[0021] According to the renewal rate of active materials during charging and discharging of the frequency-modulated liquid flow battery energy storage system, the electrolyte flow operating range of the frequency-modulated liquid flow battery energy storage system is calculated and determined.

[0022] In one embodiment, according to the state of charge equation and the open circuit voltage formula, calculating the theoretical state of charge and open circuit voltage of the frequency modulated liquid flow battery energy storage module includes:

[0023] Based on the proportion of each ion in the electrolyte of the frequency-modulated liquid flow battery energy storage module, the state of charge equation is constructed; based on the electromotive force of the frequency-modulated liquid flow battery energy storage module, the open circuit voltage formula is constructed as a function of the activity of each valence ion in the electrolyte and the theoretical state of charge of the electrolyte;

[0024] The theoretical state of charge and open circuit voltage of the frequency-modulated liquid flow battery energy storage module are calculated using the state of charge equation and open circuit voltage formula.

[0025] In one embodiment, the calculation results of the theoretical state of charge and the open circuit voltage are visualized to obtain the relationship between the theoretical state of charge and the open circuit voltage, including:

[0026] Substituting the state of charge equation into the open circuit voltage formula, we get the relationship formula between the open circuit voltage and the theoretical state of charge;

[0027] According to the relationship formula between open circuit voltage and theoretical state of charge, the open circuit voltage and theoretical state of charge of the frequency-modulated liquid flow battery energy storage module are calculated and accumulated;

[0028] The open circuit voltage and theoretical state of charge data of the frequency-modulated liquid flow battery energy storage module are normalized to obtain the relationship between the theoretical state of charge and the open circuit voltage.

[0029] In one embodiment, by measuring the actual open circuit voltage of the frequency modulated liquid flow battery energy storage module and combining the relationship between the theoretical state of charge and the open circuit voltage, the actual state of charge of the frequency modulated liquid flow battery energy storage module is obtained, including:

[0030] The actual open circuit voltage of the frequency-modulated liquid flow battery energy storage module is obtained, and the actual open circuit voltage is substituted into the relationship between the theoretical state of charge and the open circuit voltage to obtain the corresponding theoretical state of charge, and the corresponding theoretical state of charge is used as the actual state of charge of the frequency-modulated liquid flow battery energy storage module.

[0031] In one embodiment, obtaining the actual state of charge of the frequency modulated liquid flow battery energy storage module includes:

[0032] When the actual open circuit voltage is greater than the preset open circuit voltage upper limit, the charge state of the frequency-modulated liquid flow battery energy storage module is a fully charged state; when the actual open circuit voltage is less than the preset open circuit voltage lower limit, the charge state of the frequency-modulated liquid flow battery energy storage module is a depleted state.

[0033] According to a second aspect of an embodiment of the present invention, a frequency-modulated liquid flow battery energy storage control system is provided.

[0034] In one embodiment, the frequency-modulated liquid flow battery energy storage control system includes:

[0035] The electrolyte flow balance control module is used to balance the electrolyte flow of the flow battery energy storage module based on the frequency conversion control technology and combined with the flow control measures of the electrolyte valve and the flow monitoring measures of the electrolyte flow meter to obtain a frequency-modulated liquid flow battery energy storage system, and the frequency-modulated liquid flow battery energy storage system includes a plurality of frequency-modulated liquid flow battery energy storage modules;

[0036] The relationship law construction module is used to calculate the theoretical state of charge and open circuit voltage of the frequency-modulated liquid flow battery energy storage module according to the state of charge equation and the open circuit voltage formula; the calculation results of the theoretical state of charge and the open circuit voltage are visualized to obtain the relationship law between the theoretical state of charge and the open circuit voltage;

[0037] The actual state of charge acquisition module is used to obtain the actual state of charge of the frequency-modulated liquid flow battery energy storage module by measuring the actual open circuit voltage of the frequency-modulated liquid flow battery energy storage module and combining the relationship between the theoretical state of charge and the open circuit voltage;

[0038] The energy storage control module is used to integrate the electrolyte flow, actual state of charge, temperature and health status of the frequency-modulated liquid flow battery energy storage module using a controller to obtain the energy storage state of the frequency-modulated liquid flow battery energy storage module; and to control the energy storage of the frequency-modulated liquid flow battery energy storage module according to the energy storage state of the frequency-modulated liquid flow battery energy storage module.

[0039] In one embodiment, based on the frequency conversion control technology, combined with the flow control measures of the electrolyte valve and the flow monitoring measures of the electrolyte flow meter, the electrolyte flow of the flow battery energy storage module is balanced controlled, including:

[0040] The electrolyte flow rate of each stack positive electrode and negative electrode in the liquid flow battery energy storage module is controlled by the electrolyte valve;

[0041] The electrolyte flow rate of each stack positive electrode and negative electrode in the flow battery energy storage module is measured by an electrolyte flow meter;

[0042] The frequency conversion control technology is adopted to perform frequency conversion control on the positive electrode electrolyte pump and the negative electrode electrolyte pump, so that the electrolyte flow rate flowing inside each fuel cell stack is the same, and the positive electrode electrolyte flow rate entering each fuel cell stack is the same, and the negative electrode electrolyte flow rate entering each fuel cell stack is the same.

[0043] In one embodiment, frequency conversion control of the positive electrolyte pump and the negative electrolyte pump includes:

[0044] A positive electrode electrolyte pump is used to drive the positive electrode electrolyte through the battery stack and finally flows back to the positive electrode storage tank; a negative electrode electrolyte pump is used to drive the negative electrode electrolyte through the battery stack and finally flows back to the negative electrode storage tank;

[0045] According to the renewal rate of active materials during charging and discharging of the frequency-modulated liquid flow battery energy storage system, the electrolyte flow operating range of the frequency-modulated liquid flow battery energy storage system is calculated and determined.

[0046] In one embodiment, according to the state of charge equation and the open circuit voltage formula, calculating the theoretical state of charge and open circuit voltage of the frequency modulated liquid flow battery energy storage module includes:

[0047] Based on the proportion of each ion in the electrolyte of the frequency-modulated liquid flow battery energy storage module, the state of charge equation is constructed; based on the electromotive force of the frequency-modulated liquid flow battery energy storage module, the open circuit voltage formula is constructed as a function of the activity of each valence ion in the electrolyte and the theoretical state of charge of the electrolyte;

[0048] The theoretical state of charge and open circuit voltage of the frequency-modulated liquid flow battery energy storage module are calculated using the state of charge equation and open circuit voltage formula.

[0049] In one embodiment, the calculation results of the theoretical state of charge and the open circuit voltage are visualized to obtain the relationship between the theoretical state of charge and the open circuit voltage, including:

[0050] Substituting the state of charge equation into the open circuit voltage formula, we get the relationship formula between the open circuit voltage and the theoretical state of charge;

[0051] According to the relationship formula between open circuit voltage and theoretical state of charge, the open circuit voltage and theoretical state of charge of the frequency-modulated liquid flow battery energy storage module are calculated and accumulated;

[0052] The open circuit voltage and theoretical state of charge data of the frequency-modulated liquid flow battery energy storage module are normalized to obtain the relationship between the theoretical state of charge and the open circuit voltage.

[0053] In one embodiment, by measuring the actual open circuit voltage of the frequency modulated liquid flow battery energy storage module and combining the relationship between the theoretical state of charge and the open circuit voltage, the actual state of charge of the frequency modulated liquid flow battery energy storage module is obtained, including:

[0054] The actual open circuit voltage of the frequency-modulated liquid flow battery energy storage module is obtained, and the actual open circuit voltage is substituted into the relationship between the theoretical state of charge and the open circuit voltage to obtain the corresponding theoretical state of charge, and the corresponding theoretical state of charge is used as the actual state of charge of the frequency-modulated liquid flow battery energy storage module.

[0055] In one embodiment, obtaining the actual state of charge of the frequency modulated liquid flow battery energy storage module includes:

[0056] When the actual open circuit voltage is greater than the preset open circuit voltage upper limit, the charge state of the frequency-modulated liquid flow battery energy storage module is a fully charged state; when the actual open circuit voltage is less than the preset open circuit voltage lower limit, the charge state of the frequency-modulated liquid flow battery energy storage module is a depleted state.

[0057] According to a third aspect of an embodiment of the present invention, a computer device is provided.

[0058] In some embodiments, the computer device includes a memory and a processor, the memory stores a computer program, and the processor implements the steps of the above method when executing the computer program.

[0059] According to a fourth aspect of embodiments of the present invention, a computer-readable storage medium is provided.

[0060] In one embodiment, the computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, the steps of the above method are implemented.

[0061] The technical solution provided by the embodiment of the present invention may have the following beneficial effects:

[0062] The present invention provides a frequency-modulated liquid flow battery energy storage control method, system, device and medium, wherein the liquid flow battery is an all-vanadium liquid flow battery, and the independent BMS of each unit battery energy storage module is cancelled. All control functions are completed by the controller in a unified manner, which can greatly improve the independence of the unit battery module of the liquid flow energy storage system. It is mainly suitable for large-scale liquid flow energy storage systems in power systems, and solves the problem that multiple BMS are difficult to coordinate and unify, and there is poor uniformity of single cells inside the unit battery energy storage module. The present invention constructs the relationship between the state of charge and the open circuit voltage of the liquid flow battery, reduces the calculation error of the actual state of charge, and the calculation time is fast, not exceeding 50ms.

[0063] It is to be understood that the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0064] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the invention and, together with the description, serve to explain the principles of the invention.

[0065] Figure 1 is a flow chart of a frequency-modulated liquid flow battery energy storage control method according to an exemplary embodiment;

[0066] Figure 2 It is a principle block diagram of a frequency-modulated liquid flow battery energy storage control system according to an exemplary embodiment;

[0067] Figure 3 is a structural schematic diagram of a computer device according to an exemplary embodiment;

[0068] Figure 4 is a schematic diagram of a large-scale liquid flow battery energy storage system according to an exemplary embodiment;

[0069] Figure 5 is a schematic diagram of an electrolyte pump control scheme according to an exemplary embodiment;

[0070] Figure 6 is a schematic diagram of a valve control scheme according to an exemplary embodiment;

[0071] Figure 7 is a diagram showing a relationship between a state of charge and an open circuit voltage according to an exemplary embodiment. DETAILED DESCRIPTION

[0072] The following description and accompanying drawings fully illustrate the specific embodiments of this article so that those skilled in the art can practice them. Parts and features of some embodiments may be included in or replace parts and features of other embodiments. The scope of the embodiments of this article includes the entire scope of the claims, as well as all available equivalents of the claims. Herein, the terms "first", "second", etc. are only used to distinguish one element from another, without requiring or implying any actual relationship or order between these elements. In fact, the first element can also be called the second element, and vice versa. Moreover, the terms "include", "comprise" or any other variant thereof are intended to cover non-exclusive inclusion, so that the structure, device or equipment including a series of elements includes not only those elements, but also other elements that are not explicitly listed, or also include elements inherent to such structure, device or equipment. In the absence of more restrictions, the elements defined by the sentence "including one..." do not exclude the existence of other identical elements in the structure, device or equipment including the elements. Each embodiment is described in a progressive manner herein, and each embodiment focuses on the differences from other embodiments, and the same and similar parts between the embodiments can be referred to each other.

[0073] The terms "longitudinal", "lateral", "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc. in this document indicate the orientation or position relationship based on the orientation or position relationship shown in the drawings, and are only for the convenience of describing this document and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operate in a specific orientation, and therefore cannot be understood as a limitation on the present invention. In the description of this document, unless otherwise specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a mechanical connection or an electrical connection, it can also be the internal communication of two elements, it can be a direct connection, or it can be an indirect connection through an intermediate medium. For ordinary technicians in this field, the specific meanings of the above terms can be understood according to specific circumstances.

[0074] As used herein, the term "plurality" means two or more than two, unless otherwise specified.

[0075] In this document, the character " / " indicates that the preceding and following objects are in an "or" relationship. For example, A / B means: A or B.

[0076] In this article, the term "and / or" is a description of the association relationship between objects, indicating that three relationships may exist. For example, A and / or B means: A or B, or, A and B.

[0077] It should be understood that, although the various steps in the flow chart are displayed in sequence according to the indication of the arrows, these steps are not necessarily executed in sequence according to the order indicated by the arrows. Unless there is a clear description in this article, the execution of these steps is not strictly limited in order, and these steps can be executed in other orders. Moreover, at least a portion of the steps in the figure may include multiple sub-steps or multiple stages, and these sub-steps or stages are not necessarily executed at the same time, but can be executed at different times, and the execution order of these sub-steps or stages is not necessarily to be carried out in sequence, but can be executed in turn or alternately with other steps or at least a portion of the sub-steps or stages of other steps.

[0078] Each module in the device or system of the present application can be implemented in whole or in part by software, hardware, or a combination thereof. The above modules can be embedded in or independent of a processor in a computer device in the form of hardware, or can be stored in a memory in a computer device in the form of software, so that the processor can call and execute operations corresponding to the above modules.

[0079] In the absence of conflict, the embodiments of the present invention and the features of the embodiments may be combined with each other.

[0080] Figure 1 An embodiment of a frequency-modulated liquid flow battery energy storage control method of the present invention is shown.

[0081] In this optional embodiment, the frequency-modulated liquid flow battery energy storage control method includes:

[0082] S101. Based on the frequency conversion control technology, combined with the flow control measures of the electrolyte valve and the flow monitoring measures of the electrolyte flow meter, the electrolyte flow of the flow battery energy storage module is balanced controlled to obtain a frequency modulation type liquid flow battery energy storage system, and the frequency modulation type liquid flow battery energy storage system includes a plurality of frequency modulation type liquid flow battery energy storage modules;

[0083] S103, calculating the theoretical state of charge and open circuit voltage of the frequency-modulated liquid flow battery energy storage module according to the state of charge equation and the open circuit voltage formula; visualizing the calculation results of the theoretical state of charge and the open circuit voltage to obtain the relationship between the theoretical state of charge and the open circuit voltage;

[0084] S105, obtaining the actual state of charge of the frequency-modulated liquid flow battery energy storage module by measuring the actual open circuit voltage of the frequency-modulated liquid flow battery energy storage module and combining the relationship between the theoretical state of charge and the open circuit voltage;

[0085] S107, using a controller to integrate the electrolyte flow, actual state of charge, temperature and health status of the frequency-modulated liquid flow battery energy storage module to obtain the energy storage state of the frequency-modulated liquid flow battery energy storage module; and performing energy storage control on the frequency-modulated liquid flow battery energy storage module according to the energy storage state of the frequency-modulated liquid flow battery energy storage module.

[0086] Figure 2 An embodiment of a frequency-modulated liquid flow battery energy storage control system of the present invention is shown.

[0087] In this optional embodiment, the frequency-modulated liquid flow battery energy storage control system includes:

[0088] The electrolyte flow balance control module 201 is used to balance the electrolyte flow of the flow battery energy storage module based on the frequency conversion control technology and in combination with the flow control measures of the electrolyte valve and the flow monitoring measures of the electrolyte flow meter to obtain a frequency-modulated liquid flow battery energy storage system, and the frequency-modulated liquid flow battery energy storage system includes a plurality of frequency-modulated liquid flow battery energy storage modules;

[0089] The relationship law construction module 203 is used to calculate the theoretical state of charge and open circuit voltage of the frequency-modulated liquid flow battery energy storage module according to the state of charge equation and the open circuit voltage formula; visualize the calculation results of the theoretical state of charge and the open circuit voltage to obtain the relationship law between the theoretical state of charge and the open circuit voltage;

[0090] The actual state of charge acquisition module 205 is used to obtain the actual state of charge of the frequency-modulated liquid flow battery energy storage module by measuring the actual open circuit voltage of the frequency-modulated liquid flow battery energy storage module and combining the relationship between the theoretical state of charge and the open circuit voltage;

[0091] The energy storage control module 207 is used to use the controller to integrate the electrolyte flow, actual state of charge, temperature and health status of the frequency-modulated liquid flow battery energy storage module to obtain the energy storage state of the frequency-modulated liquid flow battery energy storage module; and perform energy storage control on the frequency-modulated liquid flow battery energy storage module according to the energy storage state of the frequency-modulated liquid flow battery energy storage module.

[0092] In order to facilitate understanding of the above technical solutions of the present invention, the above technical solutions of the present invention are further described below from the perspective of architecture and principle, as follows:

[0093] The liquid flow battery of the present invention is an all-vanadium liquid flow battery, which eliminates the independent BMS of each unit battery energy storage module. All control functions are uniformly completed by the controller, which can greatly improve the independence of the unit battery modules of the liquid flow energy storage system. It is mainly suitable for large-scale liquid flow energy storage systems in power systems.

[0094] The large liquid flow energy storage system, such as Figure 4As shown, it is usually composed of multiple unit battery energy storage modules, which are composed of multiple battery stacks, electrolytes, storage tanks, pumps, valves, PCS (Power Conversion System) and other equipment. The technical and functional requirements proposed by the controller include: data acquisition, temperature control, flow control, data display, data preservation, state of charge (SOC) calculation, state of health (SOH) calculation, PCS control and external data transmission. The entire energy storage system needs to be coordinated and controlled by the control system to operate safely, reliably and efficiently in the optimal state.

[0095] The pump adopts a magnetic centrifugal pump. The positive electrode electrolyte pump is used to drive the positive electrode electrolyte through the battery stack and finally flow back to the positive electrode storage tank. The negative electrode electrolyte pump is used to drive the negative electrode electrolyte through the battery stack and finally flow back to the negative electrode storage tank. According to the renewal rate of the active material during the charging and discharging of the all-vanadium liquid flow battery system, the electrolyte flow operating range of the battery system is calculated and determined, and a 5%-10% margin is added as the pump flow.

[0096] like Figure 4 As shown, valve No. +1 is the positive electrode electrolyte inlet valve of #1 fuel cell stack, valve No. -1 is the negative electrode electrolyte inlet valve of #1 fuel cell stack, and so on, valve No. +n is the positive electrode electrolyte inlet valve of #n fuel cell stack, valve No. -n is the negative electrode electrolyte inlet valve of #n fuel cell stack, and all valves are electric regulating valves that can flexibly control the electrolyte flow entering the fuel cell stack.

[0097] like Figure 4 As shown, the positive electrode total flow meter is used to measure the total flow of the positive electrode electrolyte in real time, the negative electrode total flow meter is used to measure the total flow of the negative electrode electrolyte in real time, the +1 flow meter is used to measure the positive electrode electrolyte flow of the #1 stack in real time, the -1 flow meter is used to measure the negative electrode electrolyte flow of the #1 stack in real time, and so on, the +n flow meter is used to measure the positive electrode electrolyte flow of the #n stack in real time, the -n flow meter is used to measure the negative electrode electrolyte flow of the #n stack in real time, and all flow data are transmitted to the controller in real time.

[0098] In order to improve the frequency regulation performance of the liquid flow energy storage system, it is necessary to improve the balance of the chemical reactions of each fuel cell stack and make the electrolyte flow rate flowing inside each fuel cell stack the same to the greatest extent; the total flow rate of the positive electrode electrolyte is equal to the total flow rate of the negative electrode electrolyte, the positive electrode electrolyte flow rate entering each fuel cell stack is the same, and the negative electrode electrolyte flow rate entering each fuel cell stack is the same.

[0099] In order to make the total flow rate of the positive electrolyte equal to the total flow rate of the negative electrolyte, the positive electrolyte pump and the negative electrolyte pump adopt frequency conversion control, that is, the electrolyte flow rate is controlled by the frequency of the pump. The control scheme is as follows: Figure 5As shown. A PID controller is used to control the positive and negative electrolyte flow rates. The two use the same total flow setting value. 正 Controllers and PID 负 The controller calculates and outputs the positive pump frequency command and the negative pump frequency command. Figure 4 The instructions are transmitted from the controller to each unit battery energy storage module in real time.

[0100] Valve control scheme, such as Figure 6 As shown, a PID controller is used to control the flow of each electrolyte entering the battery stack. The controlled quantity of the PID controller is the flow of the battery stack electrolyte. The set value of the PID controller is the total electrolyte flow set value divided by n. The output of the PID is the opening instruction of each valve. 1正 The controller corresponds to the opening instruction of valve +1, PID 1负 The controller corresponds to the opening instruction of valve No. -1, PID n正 The controller corresponds to the +n valve opening instruction, PID n负 The controller corresponds to the valve opening instruction No. -n.

[0101] SOC online calculation includes:

[0102] SOC stands for the state of charge of the all-vanadium redox flow battery, which indicates the amount of electricity contained in the electrolyte of the all-vanadium redox flow battery. The present invention defines SOC by the proportion of each ion in the electrolyte. The SOC formula is as follows:

[0103]

[0104]

[0105] Wherein, c represents the concentration of vanadium ions in various valence states.

[0106] Open circuit voltage U oc Refers to the voltage when there is no current flowing through the battery. In engineering applications, the open circuit voltage is numerically equal to the electromotive force E. The electromotive force of the flow battery is a function of the activity of vanadium ions in various valence states in the electrolyte and the theoretical SOC of the electrolyte. The formula is as follows:

[0107]

[0108] In the formula, E + Represents the positive electrode relative potential (V); E - Represents the positive electrode relative potential (V); E θIt represents the difference between the standard electrode potential of the positive and negative electrodes, and its value is 1.255V; α represents the activity of vanadium ions in various valence states (mol / L); γ represents the activity coefficient of vanadium ions in various valence states; c represents the concentration of vanadium ions in various valence states (mol / L); K represents a constant related to the activity coefficient; R represents the gas molar constant; T represents the absolute temperature; n represents the number of moles of electrons transferred in the battery reaction; F represents the Faraday constant, V represents vanadium ions, O represents oxygen ions, and H represents hydrogen ions.

[0109] The initial concentration and ratio of the positive and negative electrolytes are the same, and the influence of ion migration and side reactions occurring during the charge and discharge process is ignored. As the charge and discharge process proceeds, the theoretical SOC of the positive and negative electrolytes should be the same, that is:

[0110] SOC 理论 =SOC 负-理论 =SOC 正+理论

[0111] Substituting the SOC equation into the open circuit voltage formula, we have:

[0112]

[0113] Formula (4) is the relationship between the open circuit voltage of a flow battery and the theoretical SOC, but there is a large error in using this formula to solve the actual SOC in engineering applications.

[0114] The present invention proposes a method, in the process of liquid flow energy storage operation, by continuously using formula (4) to calculate and accumulate data, many groups (U oc , SOC) data. When enough data is accumulated, the data is normalized and the following can be obtained: Figure 7 The relationship between SOC and open circuit voltage is shown in Figure 1. Figure 7 , liquid flow energy storage can measure the open circuit voltage in real time during actual operation, and view it in real time Figure 7 , the actual SOC of liquid flow energy storage can be obtained in real time, and the single calculation time does not exceed 50ms.

[0115] S0C and U oc The relationship curve between U oc The simulation was performed in the range of 1.25-1.50V. oc At or above 1.50V, the SOC is specified to be 100%, and at or below 1.25V, the SOC is specified to be 0%.

[0116] In one embodiment, a computer device is provided. The computer device may be a server, and its internal structure diagram may be as follows: Figure 3As shown. The computer device includes a processor, a memory and a network interface connected through a system bus. Among them, the processor of the computer device is used to provide computing and control capabilities. The memory of the computer device includes a non-volatile storage medium and an internal memory. The non-volatile storage medium stores an operating system, a computer program and a database. The internal memory provides an environment for the operation of the operating system and the computer program in the non-volatile storage medium. The database of the computer device is used to store static information and dynamic information data. The network interface of the computer device is used to communicate with an external terminal through a network connection. When the computer program is executed by the processor, the steps in the above method embodiment are implemented.

[0117] Those skilled in the art will understand that Figure 3 The structure shown in the figure is only a block diagram of a part of the structure related to the solution of the present invention, and does not constitute a limitation on the computer device to which the solution of the present invention is applied. The specific computer device may include more or fewer components than those shown in the figure, or combine certain components, or have a different arrangement of components.

[0118] In addition, the present invention also provides a computer device, including a memory and a processor, wherein a computer program is stored in the memory, and the processor implements the steps in the above method embodiment when executing the computer program.

[0119] In addition, the present invention further provides a computer-readable storage medium on which a computer program is stored. When the computer program is executed by a processor, the steps in the above method embodiment are implemented.

[0120] Those skilled in the art can understand that all or part of the processes in the above-mentioned embodiment methods can be completed by instructing the relevant hardware through a computer program, and the computer program can be stored in a non-volatile computer-readable storage medium. When the computer program is executed, it can include the processes of the embodiments of the above-mentioned methods. Among them, any reference to memory, storage, database or other media used in the embodiments provided by the present invention can include at least one of non-volatile and volatile memory. Non-volatile memory can include read-only memory (ROM), magnetic tape, floppy disk, flash memory or optical memory, etc. Volatile memory can include random access memory (RAM) or external cache memory. As an illustration and not limitation, RAM can be in various forms, such as static random access memory (SRAM) or dynamic random access memory (DRAM).

[0121] The present invention is not limited to the structures which have been described above and shown in the drawings, and various modifications and changes may be made without departing from the scope thereof. The scope of the present invention is limited only by the appended claims.

Claims

1. A frequency-modulated liquid flow battery energy storage control method, characterized in that: The method includes: Based on the frequency conversion control technology, combined with the flow control measures of the electrolyte valve and the flow monitoring measures of the electrolyte flow meter, the electrolyte flow of the flow battery energy storage module is balanced controlled to obtain a frequency modulation type flow battery energy storage system, and the frequency modulation type flow battery energy storage system includes a plurality of frequency modulation type flow battery energy storage modules; According to the state of charge equation and the open circuit voltage formula, the theoretical state of charge and open circuit voltage of the frequency-modulated liquid flow battery energy storage module are calculated; the calculation results of the theoretical state of charge and open circuit voltage are visualized to obtain the relationship between the theoretical state of charge and the open circuit voltage; By measuring the actual open circuit voltage of the frequency modulated liquid flow battery energy storage module and combining the relationship between the theoretical state of charge and the open circuit voltage, the actual state of charge of the frequency modulated liquid flow battery energy storage module is obtained; The controller is used to integrate the electrolyte flow, actual state of charge, temperature and health status of the frequency-modulated liquid flow battery energy storage module to obtain the energy storage state of the frequency-modulated liquid flow battery energy storage module; the energy storage of the frequency-modulated liquid flow battery energy storage module is controlled according to the energy storage state of the frequency-modulated liquid flow battery energy storage module.

2. A frequency modulated liquid flow battery energy storage control method according to claim 1, characterized in that: The method of balancing the electrolyte flow rate of the flow battery energy storage module based on the variable frequency control technology and combining the flow control measures of the electrolyte valve and the flow monitoring measures of the electrolyte flow meter includes: The electrolyte flow rate of each stack positive electrode and negative electrode in the liquid flow battery energy storage module is controlled by the electrolyte valve; The electrolyte flow rate of each stack positive electrode and negative electrode in the flow battery energy storage module is measured by an electrolyte flow meter; The frequency conversion control technology is adopted to perform frequency conversion control on the positive electrode electrolyte pump and the negative electrode electrolyte pump, so that the electrolyte flow rate flowing inside each fuel cell stack is the same, and the positive electrode electrolyte flow rate entering each fuel cell stack is the same, and the negative electrode electrolyte flow rate entering each fuel cell stack is the same.

3. A frequency modulated liquid flow battery energy storage control method according to claim 2, characterized in that: The frequency conversion control of the positive electrode electrolyte pump and the negative electrode electrolyte pump comprises: A positive electrode electrolyte pump is used to drive the positive electrode electrolyte through the battery stack and finally flows back to the positive electrode storage tank; a negative electrode electrolyte pump is used to drive the negative electrode electrolyte through the battery stack and finally flows back to the negative electrode storage tank; According to the renewal rate of active materials during charging and discharging of the frequency-modulated liquid flow battery energy storage system, the electrolyte flow operating range of the frequency-modulated liquid flow battery energy storage system is calculated and determined.

4. A frequency modulated liquid flow battery energy storage control method according to claim 1, characterized in that: The calculation of the theoretical state of charge and open circuit voltage of the frequency modulated liquid flow battery energy storage module according to the state of charge equation and the open circuit voltage formula includes: Based on the proportion of each ion in the electrolyte of the frequency-modulated liquid flow battery energy storage module, the state of charge equation is constructed; based on the electromotive force of the frequency-modulated liquid flow battery energy storage module, the open circuit voltage formula is constructed as a function of the activity of each valence ion in the electrolyte and the theoretical state of charge of the electrolyte; The theoretical state of charge and open circuit voltage of the frequency-modulated liquid flow battery energy storage module are calculated using the state of charge equation and open circuit voltage formula.

5. A frequency modulated liquid flow battery energy storage control method according to claim 4, characterized in that: The calculation results of the theoretical state of charge and the open circuit voltage are visualized to obtain the relationship between the theoretical state of charge and the open circuit voltage, including: Substituting the state of charge equation into the open circuit voltage formula, we get the relationship formula between the open circuit voltage and the theoretical state of charge; According to the relationship formula between open circuit voltage and theoretical state of charge, the open circuit voltage and theoretical state of charge of the frequency-modulated liquid flow battery energy storage module are calculated and accumulated; The open circuit voltage and theoretical state of charge data of the frequency-modulated liquid flow battery energy storage module are normalized to obtain the relationship between the theoretical state of charge and the open circuit voltage.

6. A frequency modulated liquid flow battery energy storage control method according to claim 1, characterized in that: The actual state of charge of the frequency-modulated liquid flow battery energy storage module is obtained by measuring the actual open circuit voltage of the frequency-modulated liquid flow battery energy storage module and combining the relationship between the theoretical state of charge and the open circuit voltage, including: The actual open circuit voltage of the frequency-modulated liquid flow battery energy storage module is obtained, and the actual open circuit voltage is substituted into the relationship between the theoretical state of charge and the open circuit voltage to obtain the corresponding theoretical state of charge, and the corresponding theoretical state of charge is used as the actual state of charge of the frequency-modulated liquid flow battery energy storage module.

7. A frequency modulated liquid flow battery energy storage control method according to claim 1, characterized in that: The method of obtaining the actual state of charge of the frequency-modulated liquid flow battery energy storage module includes: When the actual open circuit voltage is greater than the preset open circuit voltage upper limit, the charge state of the frequency-modulated liquid flow battery energy storage module is a fully charged state; when the actual open circuit voltage is less than the preset open circuit voltage lower limit, the charge state of the frequency-modulated liquid flow battery energy storage module is a depleted state.

8. A frequency-modulated liquid flow battery energy storage control system, characterized in that: The system includes: The electrolyte flow balance control module is used to balance the electrolyte flow of the flow battery energy storage module based on the frequency conversion control technology and combined with the flow control measures of the electrolyte valve and the flow monitoring measures of the electrolyte flow meter to obtain a frequency-modulated liquid flow battery energy storage system, and the frequency-modulated liquid flow battery energy storage system includes a plurality of frequency-modulated liquid flow battery energy storage modules; The relationship law construction module is used to calculate the theoretical state of charge and open circuit voltage of the frequency-modulated liquid flow battery energy storage module according to the state of charge equation and the open circuit voltage formula; the calculation results of the theoretical state of charge and the open circuit voltage are visualized to obtain the relationship law between the theoretical state of charge and the open circuit voltage; The actual state of charge acquisition module is used to obtain the actual state of charge of the frequency-modulated liquid flow battery energy storage module by measuring the actual open circuit voltage of the frequency-modulated liquid flow battery energy storage module and combining the relationship between the theoretical state of charge and the open circuit voltage; The energy storage control module is used to integrate the electrolyte flow, actual state of charge, temperature and health status of the frequency-modulated liquid flow battery energy storage module using a controller to obtain the energy storage state of the frequency-modulated liquid flow battery energy storage module; and to control the energy storage of the frequency-modulated liquid flow battery energy storage module according to the energy storage state of the frequency-modulated liquid flow battery energy storage module.

9. A frequency modulated liquid flow battery energy storage control system according to claim 8, characterized in that: The method of balancing the electrolyte flow rate of the flow battery energy storage module based on the variable frequency control technology and combining the flow control measures of the electrolyte valve and the flow monitoring measures of the electrolyte flow meter includes: The electrolyte flow rate of each stack positive electrode and negative electrode in the liquid flow battery energy storage module is controlled by the electrolyte valve; The electrolyte flow rate of each stack positive electrode and negative electrode in the flow battery energy storage module is measured by an electrolyte flow meter; The frequency conversion control technology is adopted to perform frequency conversion control on the positive electrode electrolyte pump and the negative electrode electrolyte pump, so that the electrolyte flow rate flowing inside each fuel cell stack is the same, and the positive electrode electrolyte flow rate entering each fuel cell stack is the same, and the negative electrode electrolyte flow rate entering each fuel cell stack is the same.

10. A frequency modulated liquid flow battery energy storage control system according to claim 9, characterized in that: The frequency conversion control of the positive electrode electrolyte pump and the negative electrode electrolyte pump comprises: A positive electrode electrolyte pump is used to drive the positive electrode electrolyte through the battery stack and finally flows back to the positive electrode storage tank; a negative electrode electrolyte pump is used to drive the negative electrode electrolyte through the battery stack and finally flows back to the negative electrode storage tank; According to the renewal rate of active materials during charging and discharging of the frequency-modulated liquid flow battery energy storage system, the electrolyte flow operating range of the frequency-modulated liquid flow battery energy storage system is calculated and determined.

11. A frequency modulated liquid flow battery energy storage control system according to claim 8, characterized in that: The calculation of the theoretical state of charge and open circuit voltage of the frequency modulated liquid flow battery energy storage module according to the state of charge equation and the open circuit voltage formula includes: Based on the proportion of each ion in the electrolyte of the frequency-modulated liquid flow battery energy storage module, the state of charge equation is constructed; based on the electromotive force of the frequency-modulated liquid flow battery energy storage module, the open circuit voltage formula is constructed as a function of the activity of each valence ion in the electrolyte and the theoretical state of charge of the electrolyte; The theoretical state of charge and open circuit voltage of the frequency-modulated liquid flow battery energy storage module are calculated using the state of charge equation and open circuit voltage formula.

12. A frequency modulated liquid flow battery energy storage control system according to claim 11, characterized in that: The calculation results of the theoretical state of charge and the open circuit voltage are visualized to obtain the relationship between the theoretical state of charge and the open circuit voltage, including: Substituting the state of charge equation into the open circuit voltage formula, we get the relationship formula between the open circuit voltage and the theoretical state of charge; According to the relationship formula between open circuit voltage and theoretical state of charge, the open circuit voltage and theoretical state of charge of the frequency-modulated liquid flow battery energy storage module are calculated and accumulated; The open circuit voltage and theoretical state of charge data of the frequency-modulated liquid flow battery energy storage module are normalized to obtain the relationship between the theoretical state of charge and the open circuit voltage.

13. A frequency modulated liquid flow battery energy storage control system according to claim 8, characterized in that: The actual state of charge of the frequency-modulated liquid flow battery energy storage module is obtained by measuring the actual open circuit voltage of the frequency-modulated liquid flow battery energy storage module and combining the relationship between the theoretical state of charge and the open circuit voltage, including: The actual open circuit voltage of the frequency-modulated liquid flow battery energy storage module is obtained, and the actual open circuit voltage is substituted into the relationship between the theoretical state of charge and the open circuit voltage to obtain the corresponding theoretical state of charge, and the corresponding theoretical state of charge is used as the actual state of charge of the frequency-modulated liquid flow battery energy storage module.

14. A frequency modulated liquid flow battery energy storage control system according to claim 8, characterized in that: The method of obtaining the actual state of charge of the frequency-modulated liquid flow battery energy storage module includes: When the actual open circuit voltage is greater than the preset open circuit voltage upper limit, the charge state of the frequency-modulated liquid flow battery energy storage module is a fully charged state; when the actual open circuit voltage is less than the preset open circuit voltage lower limit, the charge state of the frequency-modulated liquid flow battery energy storage module is a depleted state.

15. A computer device comprising a memory and a processor, wherein the memory stores a computer program, wherein: When the processor executes the computer program, the steps of the method according to any one of claims 1 to 7 are implemented.

16. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the steps of the method according to any one of claims 1 to 7 are implemented.

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