A frequency modulation type flow battery energy storage control method, system, device and medium

Abstract

The application belongs to the field of battery energy storage, and discloses a frequency modulation type flow battery energy storage control method, system, device and medium. The method comprises the following steps: performing equalization control on the electrolyte flow of a flow battery energy storage module to obtain a frequency modulation type flow battery energy storage system; calculating the theoretical state of charge and open circuit voltage of the frequency modulation type flow battery energy storage module; performing visual processing on the calculation results of the theoretical state of charge and open circuit voltage to obtain the relationship between the theoretical state of charge and the open circuit voltage; measuring the actual open circuit voltage of the frequency modulation type flow battery energy storage module, combining the relationship between the theoretical state of charge and the open circuit voltage, and obtaining the actual state of charge of the frequency modulation type flow battery energy storage module; and performing energy storage control on the frequency modulation type flow battery energy storage system according to the energy storage state of the frequency modulation type flow battery energy storage system. The application improves the independence of the flow energy storage system cell module and reduces the calculation error of the actual state of charge.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of battery energy storage, in particular to a frequency modulation type flow battery energy storage control method, system, device and medium. BACKGROUND

[0002] With the rapid growth of wind power, photovoltaic and other new energy power generation, its volatility and uncertainty have posed a challenge to the stability of the power system. In order to accommodate the rapid growth of new energy, the power system needs more flexible adjustment means, and energy storage technology can balance the intermittency and instability of new energy power generation, and improve the grid connection ratio and utilization rate of new energy. Flow energy storage technology has excellent safety, long service life, green environmental protection and other characteristics, and is one of the preferred large-scale energy storage technologies. At present, flow energy storage technology is being applied more and more in the power system.

[0003] The power unit and the capacity unit of the flow battery are independent of each other and are flexible in configuration. The battery or the stack is the place where the flow battery realizes the functions of charging and discharging, and the power unit of the flow battery system is usually composed of the same by series and parallel connection. The capacity unit mainly refers to the energy storage medium of the flow battery, and the energy storage medium includes active substances, supporting electrolyte and solvent. The biggest difference between the flow battery and other traditional batteries (such as lead-acid battery, lead-carbon battery, lithium battery, etc.) is that the power unit and the capacity unit of the battery system are independent of each other.

[0004] Flow energy storage can provide flexible regulation capability for the power grid at different time scales, and can meet the needs of the power grid for primary frequency modulation (second level), secondary frequency modulation (minute level) and tertiary frequency modulation (hour level), so flow energy storage is suitable for being used as a frequency modulation power source of the power system to provide flexible regulation capability for the power system.

[0005] The large-scale flow energy storage system applied in the power system is usually composed of multiple unit battery energy storage modules, and each unit battery energy storage module has its own independent BMS control system (Battery Management System). In actual operation, it is difficult for multiple BMSs to realize coordination and unification, and there are problems such as poor uniformity of single batteries, difficulty in accurately measuring SOC in the unit battery energy storage module, which affects the frequency modulation performance of the flow battery energy storage system.

[0006] Therefore, how to provide a frequency modulation type flow battery energy storage control method, system, device and medium is a problem to be solved at present. SUMMARY

[0007] The embodiment of the present application provides a frequency modulation type flow battery energy storage control method, system, device and medium to solve the problems that multiple BMSs are difficult to realize coordination and unification, and there are problems such as poor uniformity of single batteries and difficulty in accurately measuring SOC in the unit battery energy storage module in the prior art.

[0008] The following presents a simplified summary of some aspects of the disclosed embodiments in order to provide a basic understanding of such embodiments. This summary is not an extensive overview of the embodiments and is intended neither to identify key / critical elements of the embodiments nor to delineate the scope of the embodiments. Its sole purpose is to present some concepts of the embodiments in a simplified form as a prelude to the more detailed description that is presented later.

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

[0010] In one embodiment, the frequency-modulated flow battery energy storage control method comprises:

[0011] Based on the variable frequency control technology, in combination 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, obtaining the frequency-modulated flow battery energy storage system, and the frequency-modulated flow battery energy storage system comprises a plurality of frequency-modulated 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 the open circuit voltage of the frequency-modulated flow battery energy storage module are calculated; the calculation results of the theoretical state of charge and the open circuit voltage are visualized processed, obtaining 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 flow battery energy storage module, in combination with the relationship between the theoretical state of charge and the open circuit voltage, the actual state of charge of the frequency-modulated flow battery energy storage module is obtained;

[0014] The electrolyte flow, the actual state of charge, the temperature and the health status of the frequency-modulated flow battery energy storage module are integrated by the controller, obtaining the energy storage state of the frequency-modulated flow battery energy storage system; the energy storage control of the frequency-modulated flow battery energy storage system is performed according to the energy storage state of the frequency-modulated flow battery energy storage system.

[0015] In one embodiment, the balanced control of the electrolyte flow of the flow battery energy storage module based on the variable frequency control technology, in combination with the flow control measures of the electrolyte valve and the flow monitoring measures of the electrolyte flow meter, comprises:

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

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

[0018] The frequency conversion control technology is used to control the positive electrolyte pump and the negative electrolyte pump, so that the electrolyte flow in each stack is the same, the positive electrolyte flow into each stack is the same, and the negative electrolyte flow into each stack is the same.

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

[0020] The positive electrolyte pump is used to drive the positive electrolyte to pass through the stack and finally flow back to the positive electrolyte tank, and the negative electrolyte pump is used to drive the negative electrolyte to pass through the stack and finally flow back to the negative electrolyte tank.

[0021] According to the update rate of the active substance of the frequency conversion type flow battery energy storage system during charging and discharging, the electrolyte flow operating range of the frequency conversion type flow battery energy storage system is calculated and determined.

[0022] In one embodiment, the calculation of the theoretical state of charge and the open circuit voltage of the frequency conversion type flow battery energy storage module according to the state of charge equation and the open circuit voltage formula comprises:

[0023] Based on the proportion of each ion in the electrolyte of the frequency conversion type flow battery energy storage module, a state of charge equation is constructed; according to the electromotive force of the frequency conversion type flow battery energy storage module, a function relationship is constructed between the activity of each valence state ion in the electrolyte and the theoretical state of charge of the electrolyte.

[0024] The theoretical state of charge and the open circuit voltage of the frequency conversion type flow battery energy storage module are calculated respectively by using the state of charge equation and the 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.

[0026] The state of charge equation is substituted into the open circuit voltage formula to obtain the relationship formula between the open circuit voltage and the theoretical state of charge.

[0027] According to the relationship formula between the open circuit voltage and the theoretical state of charge, the open circuit voltage and the theoretical state of charge of the frequency conversion type flow battery energy storage module are calculated and accumulated.

[0028] The open circuit voltage and the theoretical state of charge data of the frequency conversion type 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, the actual state of charge of the frequency conversion type flow battery energy storage module is obtained by measuring the actual open circuit voltage of the frequency conversion type flow battery energy storage module and combining the relationship between the theoretical state of charge and the open circuit voltage.

[0030] The actual open circuit voltage of the frequency modulation type flow battery energy storage module is obtained, 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 taken as the actual state of charge of the frequency modulation type flow battery energy storage module.

[0031] In one embodiment, obtaining the actual state of charge of the frequency modulation type flow battery energy storage module comprises:

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

[0033] According to a second aspect of the embodiment of the present application, a frequency modulation type flow battery energy storage control system is provided.

[0034] In one embodiment, the frequency modulation type flow battery energy storage control system comprises:

[0035] The electrolyte flow equalization control module is configured to perform equalization control on the electrolyte flow of the flow battery energy storage module based on the variable frequency 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 the frequency modulation type flow battery energy storage system, and the frequency modulation type flow battery energy storage system comprises a plurality of frequency modulation type flow battery energy storage modules.

[0036] The relationship rule construction module is configured to calculate the theoretical state of charge and the open circuit voltage of the frequency modulation type flow battery energy storage module according to the state of charge equation and the open circuit voltage formula, and to obtain the relationship between the theoretical state of charge and the open circuit voltage by visualizing the calculation results of the theoretical state of charge and the open circuit voltage.

[0037] The actual state of charge acquisition module is configured to obtain the actual state of charge of the frequency modulation type flow battery energy storage module by measuring the actual open circuit voltage of the frequency modulation type flow battery energy storage module and in combination with the relationship between the theoretical state of charge and the open circuit voltage.

[0038] The energy storage control module is configured to integrate the electrolyte flow, the actual state of charge, the temperature and the health status of the frequency modulation type flow battery energy storage module by using the controller to obtain the energy storage state of the frequency modulation type flow battery energy storage system, and to perform energy storage control on the frequency modulation type flow battery energy storage system according to the energy storage state of the frequency modulation type flow battery energy storage system.

[0039] In one embodiment, performing equalization control on the electrolyte flow of the flow battery energy storage module based on the variable frequency control technology and in combination with the flow control measures of the electrolyte valve and the flow monitoring measures of the electrolyte flow meter comprises:

[0040] controlling electrolyte flow of each stack anode and cathode in the flow battery energy storage module through electrolyte valve;

[0041] measuring electrolyte flow of each stack anode and cathode in the flow battery energy storage module through electrolyte flow meter;

[0042] controlling the anode electrolyte pump and the cathode electrolyte pump through frequency conversion control technology, so that the electrolyte flow in each stack is the same, the anode electrolyte flow into each stack is the same, and the cathode electrolyte flow into each stack is the same.

[0043] In one embodiment, controlling the anode electrolyte pump and the cathode electrolyte pump through frequency conversion control includes:

[0044] driving the anode electrolyte through the stack and finally flowing back to the anode liquid storage tank through the anode electrolyte pump, and driving the cathode electrolyte through the stack and finally flowing back to the cathode liquid storage tank through the cathode electrolyte pump;

[0045] According to the update rate of active substances of the frequency modulation type flow battery energy storage system during charging and discharging, the electrolyte flow operating range of the frequency modulation type flow battery energy storage system is calculated and determined.

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

[0047] Based on the proportion of each ion in the electrolyte of the frequency modulation type flow battery energy storage module, a state of charge equation is constructed; according to the electromotive force of the frequency modulation type flow battery energy storage module, a function relationship is constructed between the activity of each valence state ion in the electrolyte and the theoretical state of charge of the electrolyte, and an open circuit voltage formula is constructed;

[0048] The theoretical state of charge and open circuit voltage of the frequency modulation type flow battery energy storage module are calculated respectively by using the state of charge equation and the open circuit voltage formula.

[0049] In one embodiment, 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 includes:

[0050] Substitute the state of charge equation into the open circuit voltage formula to obtain the relationship formula between the open circuit voltage and the theoretical state of charge;

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

[0052] The open circuit voltage and the theoretical state of charge data of the frequency modulation type 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, the actual state of charge of the frequency-modulated flow battery energy storage module is obtained by measuring the actual open-circuit voltage of the frequency-modulated flow battery energy storage module, and combining the theoretical state of charge and open-circuit voltage relationship.

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

[0055] In one embodiment, the actual state of charge of the frequency-modulated flow battery energy storage module is obtained by measuring the actual open-circuit voltage of the frequency-modulated flow battery energy storage module, and combining the theoretical state of charge and open-circuit voltage relationship.

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

[0057] According to a third aspect of the embodiments of the present application, 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 the embodiments of the present application, a computer readable storage medium is provided.

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

[0061] The technical solutions provided by the embodiments of the present application can include the following beneficial effects:

[0062] The frequency-modulated flow battery energy storage control method, system, device and medium provided by the present application, in which the flow battery is a full-vanadium flow battery, cancels the independent BMS of each unit battery energy storage module, and all control functions are completed by the controller, which can greatly improve the independence of the unit battery module of the flow energy storage system. The present application is mainly suitable for large-scale flow energy storage systems in power systems, solves the problem that multiple BMSs are difficult to realize coordination and unity, and the problem of poor uniformity of single cells in the unit battery energy storage module. The present application constructs the relationship between the state of charge and the open-circuit voltage of the flow battery, reduces the calculation error of the actual state of charge, and the calculation time is rapid, not more than 50ms.

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

[0064] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the application and serve to explain the principles of the application, in which, like reference numerals designate corresponding parts throughout the several views.

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

[0066] Figure 2 is a principle block diagram of a frequency-modulated 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 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 graph of state of charge versus open circuit voltage according to an exemplary embodiment. DETAILED DESCRIPTION

[0072] The following description and drawings are illustrative of specific embodiments thereof and are not intended to limit the scope of the embodiments. Parts and features of some embodiments can be included or substituted in or for parts and features of other embodiments. The scope of the embodiments encompassed herein includes the whole scope of the claims together with all available equivalents of the claims. In this document, the terms "first", "second", etc. are used merely to distinguish one element from another, and do not require or imply any actual relationship or order between the elements. In fact, the first element can be referred to as the second element, and vice versa. Also, the terms "comprises", "comprising", or any other variations thereof are intended to cover a non-exclusive inclusion, such that a structure, device, or apparatus that comprises a list of elements does not include only those elements but can also include other elements not expressly listed or inherent to such structure, device, or apparatus. Without further limitation, an element defined by an "includes a" statement does not exclude the presence of additional identical elements in the structure, device, or apparatus that includes the element. Various embodiments are described in progressive stages, each of which focuses on the differences from other embodiments, and the same or similar parts between various embodiments can be referred to each other.

[0073] The terms "longitudinal", "lateral", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", and the like, as used herein, indicate relative positions or orientation relationships based on the positions or orientation relationships shown in the drawings, and are only used for the convenience of description herein and simplification of description, and do not indicate or imply that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the present application. In the description herein, unless otherwise specified and limited, the terms "mount", "connect", "connection" should be understood broadly, for example, it can be a mechanical connection or an electrical connection, it can be a communication between two elements inside, it can be a direct connection, or an indirect connection through an intermediate medium, and the specific meaning of the above terms can be understood by those skilled in the art according to the specific circumstances.

[0074] In this document, the term "multiple" means two or more, unless otherwise specified.

[0075] In this document, the character " / " represents an "or" relationship between the objects before and after it. For example, A / B means A or B.

[0076] In this document, the term "and / or" is a description of the relationship between the objects, which means that there can be three relationships. For example, A and / or B means that there are three relationships of A or B, or A and B.

[0077] It should be understood that although the steps in the flowchart are shown in a sequential order, the steps are not necessarily performed in the order shown by the arrows. Unless explicitly stated otherwise, the steps can be performed in other orders. Moreover, at least some of the steps can include multiple sub-steps or multiple stages, which are not necessarily performed at the same time, but can be performed at different times, and which are not necessarily performed sequentially, but can be performed in rotation or alternation with at least some of the other steps or sub-steps or stages of other steps.

[0078] The modules in the device or system of the present application can be implemented in whole or in part by software, hardware and combinations thereof. The modules can be embedded in or independent of the processor in the computer device in hardware form, or stored in the memory in the computer device in software form, so as to be called and executed by the processor to perform the operations corresponding to the modules.

[0079] In the case of no conflict, the embodiments in the present application and the features in the embodiments can be combined with each other.

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

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

[0082] S101, based on the variable frequency control technology, and 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-modulated flow battery energy storage system, and the frequency-modulated flow battery energy storage system comprises a plurality of frequency-modulated flow battery energy storage modules;

[0083] S103, according to the state of charge equation and the open circuit voltage formula, the theoretical state of charge and the open circuit voltage of the frequency-modulated flow battery energy storage module are calculated; 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;

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

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

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

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

[0088] The electrolyte flow balancing control module 201 is configured to perform balancing control on the electrolyte flow of the liquid flow battery energy storage module based on the variable frequency control technology and in combination with the flow control measures of the electrolyte valve and the flow monitoring measures of the electrolyte flowmeter to obtain the frequency-modulated liquid flow battery energy storage system, wherein the frequency-modulated liquid flow battery energy storage system comprises a plurality of frequency-modulated liquid flow battery energy storage modules.

[0089] The relationship rule construction module 203 is configured to calculate the theoretical state of charge and the 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; and perform visual processing on the calculation results of the theoretical state of charge and the open-circuit voltage to obtain the relationship rule between the theoretical state of charge and the open-circuit voltage.

[0090] The actual state of charge acquisition module 205 is configured 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 in combination with the relationship rule between the theoretical state of charge and the open-circuit voltage.

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

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

[0093] The liquid flow battery of the present application is a full-vanadium liquid flow battery, which cancels the independent BMS of each unit battery energy storage module, and all the control functions are completed by the controller, which can greatly improve the independence of the unit battery module of the liquid flow energy storage system, and is mainly suitable for large-scale liquid flow energy storage systems in power systems.

[0094] The large-scale liquid flow energy storage system, for example, Figure 4As shown, it is usually composed of multiple unit battery energy storage modules, which are composed of multiple stacks, electrolyte, storage tanks, pumps, valves, PCS (Power Conversion System, i.e. power conversion system) and other equipment. The technical and functional requirements of the controller include: data acquisition, temperature control, flow control, data display, data saving, state of charge (SOC) calculation, state of health (SOH) calculation, PCS control and external data transmission. The whole energy storage system needs to be coordinated and controlled by the control system to run in the optimal state safely, reliably and efficiently.

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

[0096] As shown in Figure 4 , the +1 valve is the #1 stack positive electrolyte inlet valve, the -1 valve is the #1 stack negative electrolyte inlet valve, and so on. The +n valve is the #n stack positive electrolyte inlet valve, and the -n valve is the #n stack negative electrolyte inlet valve. All valves are electrically adjustable valves that can be flexibly controlled to control the electrolyte flow into the stack.

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

[0098] In order to improve the frequency modulation performance of the flow energy storage system, it is necessary to improve the balance of the chemical reaction of each stack and make the electrolyte flow in each stack as equal as possible. The total flow of the positive electrolyte is equal to the total flow of the negative electrolyte, the flow of the positive electrolyte entering each stack is the same, and the flow of the negative electrolyte entering each stack is the same.

[0099] In order to make the total flow of the positive electrolyte equal to the total flow of the negative electrolyte, the positive electrolyte pump and the negative electrolyte pump are controlled by frequency control, i.e. the flow of the electrolyte is controlled by the frequency of the pump. The control scheme is as follows Figure 5The control of positive electrolyte flow and negative electrolyte flow is realized by using PID controllers, both of which adopt the same total flow set value, and the PID 正 controller and PID 负 controller calculate the positive pump frequency instruction and the negative pump frequency instruction. The above calculation is realized in the controller in Figure 4 each unit cell energy storage module.

[0100] The control scheme of the valve is shown in Fig. 3, which uses a PID controller to control the electrolyte flow into each stack, the controlled variable of the PID controller is the stack electrolyte flow, the set value of the PID controller is the total electrolyte flow set value divided by n, and the output of the PID is the valve opening degree instruction. Figure 6 The PID 1正 controller corresponds to the valve opening degree instruction of No. +1, the PID 1负 controller corresponds to the valve opening degree instruction of No. -1, the PID n正 controller corresponds to the valve opening degree instruction of No. +n, and the PID n负 controller corresponds to the valve opening degree instruction of No. -n.

[0101] The SOC online calculation includes:

[0102] SOC represents the state of charge of the all-vanadium redox flow battery, indicating the amount of electricity contained in the electrolyte of the all-vanadium redox flow battery. The present application defines SOC by the proportion of each ion in the electrolyte, and the formula of SOC is as follows:

[0103] ;

[0104] In the formula, c represents the concentration of each valence state vanadium ion.

[0105] The open circuit voltage U oc represents the voltage when there is no current passing through the outside of the battery, and in engineering applications, the open circuit voltage is equal in value to the electromotive force E. The electromotive force of the flow battery is a function of the activity of each valence state vanadium ion in the electrolyte and the theoretical SOC of the electrolyte, and the formula is as follows:

[0106] ;

[0107] In the formula, E + represents the positive relative potential (V); E - represents the negative relative potential (V); E θ represents the difference between the standard electrode potential of the positive electrode and the standard electrode potential of the negative electrode, and the value is 1.255 V; α represents the activity of each valence state vanadium ion (mol / L); gamma represents the activity coefficient of each valence state vanadium ion; and c represents the concentration of each valence state vanadium ion (mol / L); KThis represents a constant related to the activity coefficient; R Represents the gas molar constant; T The absolute temperature is represented by n; the number of moles of electrons transferred in the battery reaction is represented by F; the Faraday constant is represented by V; the vanadium ion is represented by O; and the hydrogen ion is represented by H.

[0108] The initial concentrations and ratios of the positive and negative electrode electrolytes are the same, and the effects of ion migration and side reactions during charging and discharging are ignored. As the charging and discharging process progresses, the theoretical SOC of the positive and negative electrode electrolytes should be the same, i.e.:

[0109] ;

[0110] Substituting the SOC equation into the open-circuit voltage formula, we get:

[0111] ;

[0112] Formula (4) is the relationship between the open-circuit voltage of a flow battery and the theoretical SOC. However, using this formula to solve the actual SOC in engineering applications results in a large error.

[0113] This invention proposes a method that, during the operation of fluid energy storage, continuously uses formula (4) to calculate and accumulate data, thereby obtaining many sets of (U) oc (SOC) data, once enough data has been accumulated, normalization can be performed to obtain, for example... Figure 7 The graph showing the relationship between SOC and open-circuit voltage is shown. According to... Figure 7 In actual operation, flow storage can measure open-circuit voltage in real time and view it in real time. Figure 7 It can obtain the actual SOC of fluid energy storage in real time, with a single calculation time of no more than 50ms.

[0114] S0C and U oc The relationship curve mainly applies to U oc Simulations were performed within the range of 1.25-1.50V. oc When the voltage reaches or exceeds 1.50V, the SOC is specified to be 100%; when the voltage reaches or falls below 1.25V, the SOC is specified to be 0%.

[0115] In one embodiment, a computer device is provided, which may be a server, and its internal structure diagram may be as follows: Figure 3As shown in the figure. 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, 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 operating system and the computer program in the non-volatile storage medium to run. 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 the external terminal through the network connection. The computer program is executed by the processor to implement the steps in the above method embodiments.

[0116] Those skilled in the art can understand that, Figure 3 The structure shown in the figure is only a block diagram of part of the structure related to the scheme of the present application, and does not constitute a limitation on the computer device to which the scheme of the present application is applied. The specific computer device can include more or fewer components than those shown in the figure, or combine certain components, or have a different component arrangement.

[0117] In addition, the present application also provides a computer device comprising a memory and a processor, the memory stores a computer program, and the processor executes the computer program to implement the steps in the above method embodiments.

[0118] In addition, the present application also provides a computer readable storage medium having a computer program stored thereon, and the computer program is executed by a processor to implement the steps in the above method embodiments.

[0119] Those skilled in the art can understand that all or part of the processes in the above-mentioned embodiments can be completed by a computer program instructing related hardware. 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 above-mentioned embodiments. Any reference to memory, storage, database or other medium used in the embodiments of the present application 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 but not limitation, RAM can be in various forms such as static random access memory (SRAM) or dynamic random access memory (DRAM), etc.

[0120] The present application is not limited to the structures described above and shown in the drawings, and various modifications and changes can be made without departing from the scope thereof. The scope of the present application is only limited by the appended claims.

Claims

1. A method for controlling a frequency-modulated flow battery energy storage, characterized by, The method includes: Based on frequency conversion control technology, and combined with flow control measures for electrolyte valves and flow monitoring measures for electrolyte flow meters, the electrolyte flow rate of the flow battery energy storage module is balanced and controlled to obtain a frequency-modulated flow battery energy storage system. The frequency-modulated flow battery energy storage system includes several frequency-modulated flow battery energy storage modules. Specifically, it includes: controlling the electrolyte flow rate of the positive and negative electrodes of each stack in the flow battery energy storage module through electrolyte valves; measuring the electrolyte flow rate of the positive and negative electrodes of each stack in the flow battery energy storage module through electrolyte flow meters; and using frequency conversion control technology to control the positive and negative electrolyte pumps to ensure that the electrolyte flow rate inside each stack is the same, and that the positive electrolyte flow rate and the negative electrolyte flow rate entering each stack are the same. Based on the equation of state of charge and the formula for open-circuit voltage, the theoretical state of charge and open-circuit voltage of the frequency-modulated 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. The actual open-circuit voltage of the frequency-modulated flow battery energy storage module is measured, and the relationship between the theoretical state of charge and the open-circuit voltage is combined to obtain the actual state of charge of the frequency-modulated flow battery energy storage module. The controller integrates the electrolyte flow rate, actual state of charge, temperature, and health status of the frequency-modulated flow battery energy storage module to obtain the energy storage status of the frequency-modulated flow battery energy storage system; and energy storage control is performed on the frequency-modulated flow battery energy storage system based on the energy storage status of the frequency-modulated flow battery energy storage system.

2. The frequency modulated flow battery energy storage control method of claim 1, wherein, The frequency conversion control of the positive electrolyte pump and the negative electrolyte pump includes: A positive electrolyte pump drives the positive electrolyte through the fuel cell stack and eventually returns it to the positive electrolyte storage tank; a negative electrolyte pump drives the negative electrolyte through the fuel cell stack and eventually returns it to the negative electrolyte storage tank. Based on the renewal rate of active materials during charging and discharging in the frequency-modulated flow battery energy storage system, the operating range of electrolyte flow rate for the frequency-modulated flow battery energy storage system is calculated and determined.

3. The frequency modulated flow battery energy storage control method of claim 1, wherein, The calculation of the theoretical state of charge and open-circuit voltage of the frequency-modulated flow battery energy storage module based on the state of charge equation and open-circuit voltage formula includes: Based on the proportion of each ion in the electrolyte of the frequency-modulated flow battery energy storage module, a state of charge equation is constructed; according to the electromotive force of the frequency-modulated flow battery energy storage module, which is a function of the activity of each valence state ion in the electrolyte and the theoretical state of charge of the electrolyte, an open-circuit voltage formula is constructed. Using the equation of state of charge and the formula for open-circuit voltage, the theoretical state of charge and open-circuit voltage of the frequency-modulated flow battery energy storage module are calculated respectively.

4. The frequency modulated flow battery energy storage control method of claim 3, wherein, The visualization of the calculation results of theoretical state of charge and open-circuit voltage to obtain the relationship between theoretical state of charge and open-circuit voltage includes: Substituting the state of charge equation into the open-circuit voltage formula, we obtain the formula relating the open-circuit voltage to the theoretical state of charge. Based on the formula relating open-circuit voltage to theoretical state of charge, the open-circuit voltage and theoretical state of charge of the frequency-modulated flow battery energy storage module are calculated and accumulated. The open-circuit voltage and theoretical state of charge data of the frequency-modulated flow battery energy storage module were normalized to obtain the relationship between the theoretical state of charge and the open-circuit voltage.

5. The frequency modulated flow battery energy storage control method of claim 1, wherein, The process of obtaining the actual open-circuit voltage of the frequency-modulated flow battery energy storage module by measuring the actual open-circuit voltage and combining it with the relationship between the theoretical state of charge and the open-circuit voltage includes: Obtain the actual open-circuit voltage of the frequency-modulated flow battery energy storage module, substitute the actual open-circuit voltage into the relationship between the theoretical state of charge and the open-circuit voltage to obtain the corresponding theoretical state of charge, and use the corresponding theoretical state of charge as the actual state of charge of the frequency-modulated flow battery energy storage module.

6. The frequency modulated flow battery energy storage control method of claim 1, wherein, The actual state of charge of the frequency-modulated flow battery energy storage module includes: When the actual open-circuit voltage is greater than the preset upper limit of the open-circuit voltage, the state of charge of the frequency-modulated flow battery energy storage module is fully charged; when the actual open-circuit voltage is less than the preset lower limit of the open-circuit voltage, the state of charge of the frequency-modulated flow battery energy storage module is depleted.

7. A frequency modulated flow battery energy storage control system, characterized by, The system includes: An electrolyte flow balancing control module is used to balance the electrolyte flow of a flow battery energy storage module based on frequency conversion control technology, combined with flow control measures of electrolyte valves and flow monitoring measures of electrolyte flow meters, to obtain a frequency-modulated flow battery energy storage system. The frequency-modulated flow battery energy storage system includes several frequency-modulated flow battery energy storage modules. Specifically, it includes: controlling the electrolyte flow of the positive and negative electrodes of each stack in the flow battery energy storage module through electrolyte valves; measuring the electrolyte flow of the positive and negative electrodes of each stack in the flow battery energy storage module through electrolyte flow meters; and using frequency conversion control technology to perform frequency conversion control on the positive and negative electrolyte pumps to ensure that the electrolyte flow inside each stack is the same, and that the positive electrolyte flow entering each stack is the same, and the negative electrolyte flow entering each stack is the same. The relational law construction module is used to calculate the theoretical state of charge and open-circuit voltage of the frequency-modulated flow battery energy storage module based on the state of charge equation and open-circuit voltage formula; the calculation results of the theoretical state of charge and open-circuit voltage are visualized to obtain the relational law between the theoretical state of charge and open-circuit voltage. The actual state of charge acquisition module is used to obtain the actual state of charge of the frequency-modulated flow battery energy storage module by measuring the actual open-circuit voltage of the 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 rate, actual state of charge, temperature and health status of the frequency-modulated flow battery energy storage module with the controller to obtain the energy storage status of the frequency-modulated flow battery energy storage system; and to perform energy storage control on the frequency-modulated flow battery energy storage system based on the energy storage status of the frequency-modulated flow battery energy storage system.

8. The frequency modulated flow battery energy storage control system of claim 7, wherein, The frequency conversion control of the positive electrolyte pump and the negative electrolyte pump includes: A positive electrolyte pump drives the positive electrolyte through the fuel cell stack and eventually returns it to the positive electrolyte storage tank; a negative electrolyte pump drives the negative electrolyte through the fuel cell stack and eventually returns it to the negative electrolyte storage tank. Based on the renewal rate of active materials during charging and discharging in the frequency-modulated flow battery energy storage system, the operating range of electrolyte flow rate for the frequency-modulated flow battery energy storage system is calculated and determined.

9. The frequency modulated flow battery energy storage control system of claim 7, wherein, The calculation of the theoretical state of charge and open-circuit voltage of the frequency-modulated flow battery energy storage module based on the state of charge equation and open-circuit voltage formula includes: Based on the proportion of each ion in the electrolyte of the frequency-modulated flow battery energy storage module, a state of charge equation is constructed; according to the electromotive force of the frequency-modulated flow battery energy storage module, which is a function of the activity of each valence state ion in the electrolyte and the theoretical state of charge of the electrolyte, an open-circuit voltage formula is constructed. Using the equation of state of charge and the formula for open-circuit voltage, the theoretical state of charge and open-circuit voltage of the frequency-modulated flow battery energy storage module are calculated respectively.

10. The frequency modulated flow battery energy storage control system of claim 9, wherein, The visualization of the calculation results of theoretical state of charge and open-circuit voltage to obtain the relationship between theoretical state of charge and open-circuit voltage includes: Substituting the state of charge equation into the open-circuit voltage formula, we obtain the formula relating the open-circuit voltage to the theoretical state of charge. Based on the formula relating open-circuit voltage to theoretical state of charge, the open-circuit voltage and theoretical state of charge of the frequency-modulated flow battery energy storage module are calculated and accumulated. The open-circuit voltage and theoretical state of charge data of the frequency-modulated flow battery energy storage module were normalized to obtain the relationship between the theoretical state of charge and the open-circuit voltage.

11. The frequency modulated flow battery energy storage control system of claim 7, wherein, The process of obtaining the actual open-circuit voltage of the frequency-modulated flow battery energy storage module by measuring the actual open-circuit voltage and combining it with the relationship between the theoretical state of charge and the open-circuit voltage includes: Obtain the actual open-circuit voltage of the frequency-modulated flow battery energy storage module, substitute the actual open-circuit voltage into the relationship between the theoretical state of charge and the open-circuit voltage to obtain the corresponding theoretical state of charge, and use the corresponding theoretical state of charge as the actual state of charge of the frequency-modulated flow battery energy storage module.

12. The frequency modulated flow battery energy storage control system of claim 7, wherein, The actual state of charge of the frequency-modulated flow battery energy storage module includes: When the actual open-circuit voltage is greater than the preset upper limit of the open-circuit voltage, the state of charge of the frequency-modulated flow battery energy storage module is fully charged; when the actual open-circuit voltage is less than the preset lower limit of the open-circuit voltage, the state of charge of the frequency-modulated flow battery energy storage module is depleted.

13. A computer device comprising a memory and a processor, the memory storing a computer program, characterized in that, When the processor executes the computer program, it implements the steps of the method according to any one of claims 1 to 6.

14. A computer readable storage medium having stored thereon a computer program, characterized in that, When the computer program is executed by a processor, it implements the steps of the method according to any one of claims 1 to 6.

Images