Energy storage control method, device and equipment applied to direct-current micro-grid and medium

Abstract

The invention provides an energy storage control method, device and equipment applied to a direct-current micro-grid and a medium, and belongs to the technical field of micro-grids. The energy storage system of the direct-current micro-grid comprises a plurality of energy storage units, and the method comprises the following steps: for an energy storage unit comprising a lithium battery and a direct-current converter, acquiring the output current of the lithium battery, the output current and the output voltage of the direct-current converter and the operation flag bit and the average charge state of the energy storage system at the current moment; determining a current reference signal according to the operation flag bit of the energy storage system; according to the output current of the direct current converter, the operation flag bit and the average charge state of the energy storage system and the predetermined charge state of the lithium battery at the current moment, a preset bus voltage given value is corrected; and according to the output current of the lithium battery, the output voltage of the DC converter, the current reference signal and the corrected bus voltage given value, adjusting the operation state of the DC converter. According to the invention, SOC balance among a plurality of energy storage units can be realized.

Description

Technical Field

[0001] The present application relates to the field of microgrid technology, and in particular to energy storage control methods, devices, equipment and media applied to direct current microgrids. Background Art

[0002] In the energy storage system of a DC microgrid, the SOC (State of Charge) balance between each energy storage unit is crucial to ensure the stable operation of the DC microgrid and extend the life of the energy storage battery. In the prior art, the SOC balance between each energy storage unit is usually achieved by simply weighting the SOC of each energy storage unit to calculate the charge and discharge power that each energy storage unit needs to bear. However, when the SOC differences between each energy storage unit are large, it is easy for some energy storage units to be allocated too large a charge and discharge power, while other energy storage units are allocated too small a charge and discharge power, that is, the SOC balance control effect between each energy storage unit is poor. Summary of the invention

[0003] The main purpose of this application is to propose an energy storage control method, device, equipment and medium applied to a DC microgrid, which can effectively control the charging and discharging process of multiple energy storage units contained in the DC microgrid, so that the SOC between the multiple energy storage units is balanced and the bus voltage of the DC microgrid is stabilized.

[0004] To achieve the above object, one aspect of the present application provides an energy storage control method applied to a DC microgrid, wherein the energy storage system of the DC microgrid includes multiple energy storage units, and the method includes:

[0005] For each of the energy storage units, the energy storage unit includes a lithium battery and a DC converter, obtaining the output current of the lithium battery, the output current and output voltage of the DC converter, and the operation flag and average charge state of the energy storage system at the current moment;

[0006] Determining a current reference signal according to an operation flag of the energy storage system;

[0007] Correcting a preset bus voltage given value according to the output current of the DC converter, the operation flag and the average state of charge of the energy storage system, and the predetermined state of charge of the lithium battery at the current moment;

[0008] The operating state of the DC converter is adjusted according to the output current of the lithium battery, the output voltage of the DC converter, the current reference signal and the corrected bus voltage given value.

[0009] Furthermore, the state of charge of the lithium battery at the current moment is obtained by:

[0010] Obtaining the initial state of charge of the lithium battery at a historical moment and the output current sequence of the lithium battery in a specific time period, wherein the specific time period is a time period from the next moment of the historical moment to the current moment;

[0011] According to the initial state of charge, output current sequence, rated capacity and charge and discharge efficiency of the lithium battery, the state of charge sequence of the lithium battery in the specific time period is determined, and then the state of charge of the lithium battery at the current moment is extracted therefrom.

[0012] Further, determining the current reference signal according to the operation flag of the energy storage system includes:

[0013] When the operation flag of the energy storage system is a charging flag, obtaining the terminal voltage of the lithium battery at the current moment;

[0014] The current reference signal is determined according to the terminal voltage of the lithium battery and a preset expected voltage of the lithium battery after being fully charged.

[0015] Further, determining the current reference signal according to the operation flag of the energy storage system includes:

[0016] When the operation flag of the energy storage system is a discharge flag, the current reference signal is determined according to the output voltage of the DC converter and the given value of the bus voltage.

[0017] Further, the step of correcting the preset bus voltage given value according to the output current of the DC converter, the operation flag and the average state of charge of the energy storage system, and the predetermined state of charge of the lithium battery at the current moment includes:

[0018] Determining a droop compensation voltage according to the output current of the DC converter, the operation flag and the average state of charge of the energy storage system, the state of charge of the lithium battery and a preset droop resistance;

[0019] The bus voltage given value is corrected according to the droop compensation voltage.

[0020] Furthermore, the adjusting the operating state of the DC converter according to the output current of the lithium battery, the output voltage of the DC converter, the current reference signal and the corrected bus voltage given value includes:

[0021] Determining a first current reference signal according to the output voltage of the DC converter and the corrected bus voltage given value;

[0022] Determining a voltage control signal according to the output current of the lithium battery, the current reference signal and the first current reference signal;

[0023] The output power of the DC converter is adjusted according to the voltage control signal.

[0024] To achieve the above-mentioned object, another aspect of the present application provides an energy storage control device applied to a DC microgrid, wherein the energy storage system of the DC microgrid includes a plurality of energy storage units, and the device includes a plurality of sub-controllers correspondingly configured for the plurality of energy storage units;

[0025] For each of the energy storage units, the energy storage unit includes a lithium battery and a DC converter, and the sub-controller configured for the energy storage unit is used to: obtain the output current of the lithium battery, the output current and output voltage of the DC converter, and the operation flag and average charge state of the energy storage system at the current moment; determine the current reference signal according to the operation flag of the energy storage system; correct the preset bus voltage set value according to the output current of the DC converter, the operation flag and average charge state of the energy storage system, and the predetermined charge state of the lithium battery at the current moment; adjust the operation state of the DC converter according to the output current of the lithium battery, the output voltage of the DC converter, the current reference signal and the corrected bus voltage set value.

[0026] Furthermore, the device also includes a master controller configured for the energy storage system;

[0027] The sub-controller configured for the energy storage unit is also used to generate a state of charge sequence of the lithium battery in a specific time period and send it to the main controller, wherein the specific time period includes the current moment;

[0028] The main controller is used to: obtain the charging and discharging power of the energy storage system at the current moment; determine the operation flag of the energy storage system at the current moment according to the charging and discharging power of the energy storage system; determine the average state of charge of the energy storage system at the current moment according to the multiple state of charge sequences corresponding to the multiple lithium batteries contained in the multiple energy storage units within the specific time period sent by the multiple sub-controllers; and send the operation flag and the average state of charge of the energy storage system at the current moment to each of the sub-controllers.

[0029] To achieve the above objective, another aspect of the present application provides an electronic device, the electronic device comprising a memory and a processor, the memory storing a computer program, and the processor implementing the above method when executing the computer program.

[0030] To achieve the above objective, another aspect of the present application provides a computer-readable storage medium, wherein the computer-readable storage medium stores a computer program, and the computer program implements the above method when executed by a processor.

[0031] The present application includes at least the following beneficial effects: for the lithium battery and the DC converter contained in each energy storage unit, the operation flag of the energy storage system is used to determine the current reference signal required for adjusting the operation state of the DC converter, and under the condition of comprehensively considering the charge state of the lithium battery and the average charge state of the energy storage system, the output current of the DC converter and the operation flag of the energy storage system are combined to determine the final bus voltage set value required for adjusting the operation state of the DC converter, and then the output current of the lithium battery and the output voltage of the DC converter are combined to perform analysis to adjust the operation state of the DC converter; according to the above implementation mode, the charging and discharging process of multiple energy storage units contained in the DC microgrid can be effectively controlled, so that the SOC between the multiple energy storage units is balanced, and the bus voltage of the DC microgrid is stabilized. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 It is a flow chart of an energy storage control method applied to a DC microgrid provided in an embodiment of the present application;

[0033] Figure 2 It is a structural schematic diagram of an energy storage control device applied to a DC microgrid provided in an embodiment of the present application;

[0034] Figure 3 It is a schematic diagram of the hardware structure of the electronic device provided in the embodiment of the present application. DETAILED DESCRIPTION

[0035] In order to make the purpose, technical solutions and advantages of the present application clearer, the present application is further described in detail below in conjunction with the accompanying drawings and examples. It should be understood that the specific embodiments described herein are only used to explain the present application and are not intended to limit the present application. When the following description refers to the drawings, unless otherwise indicated, the same numbers in different drawings represent the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with the embodiments of the present application. They are only examples of systems and methods consistent with some aspects of the embodiments of the present application as detailed in the attached claims.

[0036] It is understood that the terms "first", "second", etc. used in this application can be used to describe various concepts in this article, but unless otherwise specified, these concepts are not limited by these terms. These terms are only used to distinguish one concept from another concept. For example, without departing from the scope of the embodiment of the present application, the first information may also be referred to as the second information, and similarly, the second information may also be referred to as the first information. Depending on the context, the words "if" and "if" as used herein can be interpreted as "at the time of" or "when" or "in response to determination".

[0037] The terms "at least one", "multiple", "each", "any", etc. used in this application, at least one includes one, two or more, multiple includes two or more, each refers to each of the corresponding multiple, and any refers to any one of the multiple.

[0038] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which this application belongs. The terms used herein are only for the purpose of describing the embodiments of this application and are not intended to limit this application.

[0039] DC microgrid is a popular research direction, mainly used to improve the integration between renewable energy and power grid. With the widespread application of renewable energy, the role of energy storage system in DC microgrid is becoming increasingly important. Lithium battery has become the first choice in energy storage system due to its high energy density and long cycle life. Considering the physical properties of lithium battery itself, the capacity or power of a single lithium battery cannot meet the power demand of all loads. The energy storage system is more likely to be composed of multiple energy storage units.

[0040] On the one hand, due to the inconsistency of the internal resistance and self-discharge capacity of each energy storage unit, and the difference in the operating temperature range, after a long period of charge and discharge cycle, it is easy to have a large difference in the SOC between the energy storage units. At this time, the reference value representing the SOC of the energy storage system will no longer be accurate, affecting the real-time and effectiveness of the DC microgrid control; on the other hand, if the SOC of a certain energy storage unit reaches the set protection value, the energy storage unit will exit operation, which will lead to the lack of dispatchable power in the DC microgrid, thereby affecting the overall effect of the DC microgrid control. Therefore, it is necessary to coordinate the control of multiple energy storage units contained in the energy storage system to ensure that the SOC between multiple energy storage units is as balanced and consistent as possible.

[0041] In the energy storage system of a DC microgrid, the SOC (State of Charge) balance between each energy storage unit is crucial to ensure the stable operation of the DC microgrid and extend the life of the energy storage battery. In the prior art, the SOC balance between each energy storage unit is usually achieved by simply weighting the SOC of each energy storage unit to calculate the charge and discharge power that each energy storage unit needs to bear. However, when the SOC differences between each energy storage unit are large, it is easy for some energy storage units to be allocated too large a charge and discharge power, while other energy storage units are allocated too small a charge and discharge power, that is, the SOC balance control effect between each energy storage unit is poor.

[0042] In view of this, the embodiments of the present application provide an energy storage control method, device, equipment and medium applied to a DC microgrid. For the lithium battery and DC converter contained in each energy storage unit, the scheme uses the operation flag of the energy storage system to determine the current reference signal required for adjusting the operating state of the DC converter, and under the condition of comprehensively considering the charge state of the lithium battery and the average charge state of the energy storage system, the output current of the DC converter and the operation flag of the energy storage system are combined to determine the final bus voltage set value required for adjusting the operating state of the DC converter, and then the output current of the lithium battery and the output voltage of the DC converter are combined to analyze to adjust the operating state of the DC converter; according to the above implementation mode, the charging and discharging process of multiple energy storage units contained in the DC microgrid can be effectively controlled, so that the SOC between the multiple energy storage units is balanced, and the bus voltage of the DC microgrid is stabilized.

[0043] The energy storage control method for DC microgrid provided in the embodiment of the present application relates to the field of microgrid technology, and can be applied to a terminal, a server, or software running in a terminal or a server. In some embodiments, the terminal can be a smart phone, a tablet computer, a laptop computer, a desktop computer, a smart speaker, a smart watch, and a vehicle-mounted terminal, etc., but is not limited thereto; the server side can be configured as an independent physical server, or a server cluster or distributed system composed of multiple physical servers, or a cloud server that provides basic cloud computing services such as cloud services, cloud databases, cloud computing, cloud functions, cloud storage, network services, cloud communications, middleware services, domain name services, security services, CDN, and big data and artificial intelligence platforms. The server can also be a node server in a blockchain network; the software can be an application that implements the above-mentioned energy storage control method for DC microgrid, etc., but is not limited to the above forms.

[0044] The present application can be used in many general or special computer system environments or configurations. For example: personal computers, server computers, handheld or portable devices, tablet devices, multiprocessor systems, microprocessor-based systems, set-top boxes, programmable consumer electronics, network PCs, minicomputers, mainframe computers, distributed computing environments including any of the above systems or devices, etc. The present application can be described in the general context of computer-executable instructions executed by a computer, such as program modules. Generally, program modules include routines, programs, objects, components, data structures, etc. that perform specific tasks or implement specific abstract data types. The present application can also be practiced in distributed computing environments, in which tasks are performed by remote processing devices connected through a communication network. In a distributed computing environment, program modules can be located in local and remote computer storage media including storage devices.

[0045] Figure 1 is an optional flow chart of an energy storage control method applied to a DC microgrid provided in an embodiment of the present application, wherein the energy storage system of the DC microgrid includes multiple energy storage units. Figure 1 The method may include but is not limited to steps S101 to S104:

[0046] Step S101: for each energy storage unit, which includes a lithium battery and a DC converter, obtaining the output current of the lithium battery, the output current and output voltage of the DC converter, and the operation flag and average charge state of the energy storage system at the current moment;

[0047] Wherein, the lithium battery is connected to the DC microgrid via the DC converter, and the DC converter is preferably a bidirectional DC-DC converter;

[0048] Step S102, determining a current reference signal according to an operation flag of the energy storage system;

[0049] Step S103, correcting the preset bus voltage given value according to the output current of the DC converter, the operation flag and the average state of charge of the energy storage system, and the predetermined state of charge of the lithium battery at the current moment;

[0050] Step S104, adjusting the operating state of the DC converter according to the output current of the lithium battery, the output voltage of the DC converter, the current reference signal and the corrected bus voltage given value.

[0051] In steps S101 to S104 shown in the embodiment of the present application, for each energy storage unit including a DC converter and a lithium battery, by comprehensively analyzing the output current and charge state of the lithium battery, the output voltage and output current of the DC converter, and the average charge state and operation flag of the energy storage system at the current moment, the charging and discharging process of multiple energy storage units included in the DC microgrid can be effectively controlled, so that the SOC between the multiple energy storage units is balanced and the bus voltage of the DC microgrid is stabilized.

[0052] In step S103 of some embodiments, the process of determining the state of charge of the lithium battery at the current moment may include, but is not limited to, steps S201 to S203:

[0053] Step S201, obtaining the initial state of charge of the lithium battery at a historical moment and the output current sequence of the lithium battery in a specific time period;

[0054] Among them, the specific time period refers to the time period from the next moment of the historical moment to the current moment. The output current sequence of the lithium battery in the specific time period includes the output current of the lithium battery at each moment in the specific time period, which can be collected by the current sensor configured for the lithium battery.

[0055] Step S202: According to the initial state of charge, output current sequence, charge and discharge efficiency and rated capacity of the lithium battery, the state of charge sequence of the lithium battery in the specific time period is determined by the following expression:

[0056]

[0057] Wherein, SOC(t) is the state of charge of the lithium battery at time t in the specific time period. The state of charge sequence of the lithium battery in the specific time period includes the state of charge of the lithium battery at each time in the specific time period. SOC(t 0 ) is the historical moment t 0 The initial charge state of the lithium battery, Q Bat is the rated capacity of the lithium battery, i L (t) is the output current of the lithium battery at time t within the specific time period, η is the charge and discharge efficiency and is preferably set to 90%, the charging efficiency refers to the ratio of the amount of charge actually stored in the lithium battery during the charging process to the amount of charge input, and the discharging efficiency refers to the ratio of the amount of charge actually released by the lithium battery during the discharging process to the amount of charge stored. Considering that battery aging and battery temperature changes will have a certain impact on the battery SOC estimation, the charge and discharge efficiency η is regularly calibrated.

[0058] Step S203, extracting the state of charge of the lithium battery at the current moment from the state of charge sequence of the lithium battery in the specific time period, can be understood as extracting the last state of charge included in the state of charge sequence of the lithium battery in the specific time period.

[0059] In the steps S201 to S203 shown in the embodiment of the present application, the state of charge of the lithium battery at each moment in a specific time period can be estimated more accurately by adopting an enhanced coulomb counting algorithm.

[0060] In step S101 of some embodiments, since multiple state of charge sequences corresponding to multiple lithium batteries included in multiple energy storage units in the specific time period can be determined through the above steps S201 to S202, the average state of charge of the energy storage system at the current moment is mainly determined by the master controller according to multiple state of charge sequences corresponding to multiple lithium batteries included in multiple energy storage units in the specific time period, which may include but is not limited to steps S301 to S302:

[0061] Step S301: for the state of charge sequence of each lithium battery in the specific time period, the master controller samples the state of charge sequence of the lithium battery according to a preset sampling period, and then averages all the state of charge of the lithium battery obtained by sampling to obtain an average state of charge of the lithium battery;

[0062] Step S302: averaging a plurality of average states of charge corresponding to a plurality of lithium batteries in the specific time period to obtain an average state of charge of the energy storage system at the current moment.

[0063] In steps S301 to S302 shown in the embodiment of the present application, by comprehensively analyzing multiple state of charge sequences corresponding to multiple lithium batteries contained in multiple energy storage units within a specific time period, the average state of charge of the energy storage system at the current moment can be determined more stably and reliably.

[0064] In step S101 of some embodiments, the operation flag of the energy storage system at the current moment is mainly determined by the master controller, which may include but is not limited to steps S401 to S402:

[0065] Step S401, obtaining the charge and discharge power of the energy storage system at the current moment through the master controller;

[0066] Step S402: determining, by the master controller, an operation flag of the energy storage system at the current moment according to the charge and discharge power of the energy storage system;

[0067] Specifically, when the main controller identifies that the charge and discharge power of the energy storage system is greater than zero, the operation flag of the energy storage system is set to the charging flag; when the main controller identifies that the charge and discharge power of the energy storage system is less than zero, the operation flag of the energy storage system is set to the discharging flag.

[0068] It should be noted that when the main controller recognizes that the charging and discharging power of the energy storage system is equal to zero, it is impossible to set the operation flag of the energy storage system, nor will it obtain the multiple charge state sequences corresponding to the multiple lithium batteries contained in the multiple energy storage units within the specific time period, that is, it is impossible to further solve the average charge state of the energy storage system. At this time, the operating states of the multiple DC converters contained in the multiple energy storage units remain unchanged, and the current moment can be used as a new historical moment, and the charge state of the lithium battery at the current moment can be used as the initial charge state of the lithium battery at the new historical moment, and a new round of energy storage control tasks can be started after waiting for the specific time period.

[0069] In some embodiments, the above step S102 may include but is not limited to step S501 to step S502:

[0070] Step S501: when the operation flag of the energy storage system is set to the charging flag, obtaining the terminal voltage of the lithium battery at the current moment;

[0071] Step S502, determining a current reference signal according to a preset expected voltage of the lithium battery after being fully charged and a terminal voltage of the lithium battery;

[0072] Specifically, the expected voltage of the lithium battery after being fully charged is subtracted from the terminal voltage of the lithium battery to obtain a first voltage deviation; preferably, an existing PI (Proportional-Integral) control algorithm is used to analyze the first voltage deviation to obtain a first initial current reference signal; and according to the preset maximum charging current of the lithium battery, the first initial current reference signal is limited to obtain the current reference signal.

[0073] Steps S501 to S502 shown in the embodiment of the present application can assist in realizing charging control of the lithium battery by determining a current reference signal using the expected voltage of the lithium battery after being fully charged and the terminal voltage of the lithium battery, so that the terminal voltage of the lithium battery can be adjusted to the expected voltage after being fully charged.

[0074] In some embodiments, the above step S102 may further include: when the operation flag of the energy storage system is set to the discharge flag, determining a current reference signal according to a preset bus voltage given value and an output voltage of the DC converter;

[0075] Specifically, the preset bus voltage set value is subtracted from the output voltage of the DC converter to obtain a second voltage deviation; the second voltage deviation is preferably analyzed using an existing PI control algorithm to obtain a second initial current reference signal; according to the preset saturation discharge current of the lithium battery, the second initial current reference signal is limited to obtain the current reference signal; wherein the preset bus voltage set value is a bus voltage set value when no-load.

[0076] By using the bus voltage set value at no-load and the output voltage of the DC converter to determine the current reference signal, the discharge control of the lithium battery can be assisted.

[0077] In some embodiments, the above step S103 may include but is not limited to steps S601 to S602:

[0078] Step S601: Determine the droop compensation voltage by the following expression according to the average state of charge and the operation flag of the energy storage system, the output current of the DC converter, the state of charge of the lithium battery and the preset droop resistance:

[0079]

[0080] V Drop =R DT ·i O =R D ·k d ·i O

[0081] In the formula, k d is a balance compensation factor, p is a factor for convergence and p≥0, and is preferably set to 6 in this application, SOC is the state of charge of the lithium battery, A SOC is the average state of charge of the energy storage system, SW is the operation flag of the energy storage system, SW=0 indicates that the operation flag of the energy storage system is set to the charging flag, SW=1 indicates that the operation flag of the energy storage system is set to the discharging flag, V Drop is the droop compensation voltage, R D is the preset droop resistance of the lithium battery, R DT is the droop resistance after compensation, i O is the output current of the DC converter.

[0082] It should be noted that when SW = 0, when SOC-A SOC >0, it means that the corresponding energy storage unit will absorb more power from the DC microgrid than when there is no compensation effect; when SOC-A SOC <0, it means that the corresponding energy storage unit will absorb less power from the DC microgrid than when there is no compensation effect;

[0083] In the case of SW = 1, when SOC-A SOC >0, it means that the corresponding energy storage unit will provide less power to the DC microgrid than when there is no compensation effect; when SOC-A SOC <0, it indicates that the corresponding energy storage unit will provide more power to the DC microgrid than when there is no compensation effect.

[0084] Step S602: correcting the bus voltage given value according to the droop compensation voltage;

[0085] Specifically, the preset bus voltage set value is subtracted from the droop compensation voltage to obtain a corrected bus voltage set value.

[0086] In steps S601 to S602 shown in the embodiment of the present application, a droop compensation control strategy is adopted to determine the balance compensation factor to further correct the given value of the bus voltage when no-load, which is beneficial to gradually balance the charge state of the lithium battery inside the energy storage unit when the energy storage unit is in a charging mode or a discharging mode; and, the introduction of an exponential function in the droop compensation control strategy to describe the relationship between the balance compensation factor and the charge state of the lithium battery is beneficial to produce a more significant droop resistance difference between multiple energy storage units, so that the SOC between the multiple energy storage units can reach a balanced state more quickly.

[0087] In some embodiments, the above step S104 may include but is not limited to steps S701 to S703:

[0088] Step S701, determining a first current reference signal according to the corrected bus voltage given value and the output voltage of the DC converter;

[0089] Specifically, the corrected bus voltage set value is subtracted from the output voltage of the DC converter to obtain a third voltage deviation; the third voltage deviation is preferably analyzed using an existing PI control algorithm to obtain a third initial current reference signal; and the third initial current reference signal is limited according to the preset maximum output current of the DC converter to obtain the first current reference signal.

[0090] Step S702, determining a voltage control signal according to the output current of the lithium battery, the current reference signal and the first current reference signal;

[0091] Specifically, the first current reference signal is subtracted from the current reference signal to obtain a current given signal; the current given signal is subtracted from the output current of the lithium battery to obtain a current deviation signal; and the current deviation signal is preferably analyzed using an existing neural network control algorithm to obtain the voltage control signal.

[0092] Step S703, adjusting the output power of the DC converter according to the voltage control signal;

[0093] Specifically, it is preferred to use an existing PWM (Pulse Width Modulation) drive circuit to convert the voltage control signal into a PWM control signal, and then use the PWM control signal to adjust the power output of the DC converter to achieve rapid regulation of power changes.

[0094] In steps S701 to S703 shown in the embodiment of the present application, by adopting a dual closed-loop control strategy based on voltage and current to comprehensively analyze the output voltage of the DC converter, the output current of the lithium battery, the corrected bus voltage set value and the current reference signal, the power exchange between the corresponding energy storage unit and the DC microgrid can be regulated more stably and reliably to maintain the stability of the DC bus voltage of the DC microgrid.

[0095] See also Figure 2 The embodiment of the present application also provides an energy storage control device applied to a DC microgrid, which can implement the above-mentioned energy storage control method applied to a DC microgrid. The energy storage system of the DC microgrid includes multiple energy storage units. The device includes multiple sub-controllers configured corresponding to the multiple energy storage units and a main controller configured for the energy storage system, and each sub-controller is connected to the main controller.

[0096] For each energy storage unit, the energy storage unit includes a DC converter and a lithium battery. The lithium battery is connected to the DC microgrid through the DC converter. The DC converter preferably adopts a bidirectional DC-DC converter. The sub-controller configured for the energy storage unit is used to implement the following functions:

[0097] The output current of the lithium battery, the output voltage and output current of the DC converter, and the average state of charge and operation flag of the energy storage system at the current moment are obtained; a current reference signal is determined according to the operation flag of the energy storage system; a preset bus voltage given value is corrected according to the average state of charge and operation flag of the energy storage system, the output current of the DC converter, and the predetermined state of charge of the lithium battery at the current moment; the operation state of the DC converter is adjusted according to the output voltage of the DC converter, the output current of the lithium battery, the corrected bus voltage given value, and the current reference signal.

[0098] In addition, the sub-controller configured for the energy storage unit is also used to implement the following functions: generating a charge state sequence of the lithium battery within a specific time period and sending it to the main controller, and the charge state sequence of the lithium battery within the specific time period includes the charge state of the lithium battery at the current moment.

[0099] Specifically, the sub-controller generates a state of charge sequence of the lithium battery in the specific time period, and the corresponding implementation process may include but is not limited to the following:

[0100] Firstly, the initial state of charge of the lithium battery at the historical moment and the output current sequence of the lithium battery in the specific time period are obtained through the sub-controller, and the specific time period specifically refers to the time period from the next moment of the historical moment to the current moment; secondly, the state of charge sequence of the lithium battery in the specific time period is determined through the sub-controller according to the initial state of charge of the lithium battery, the output current sequence, the charge and discharge efficiency and the rated capacity.

[0101] Before the multiple sub-controllers adjust the operating states of the multiple DC converters included in the corresponding multiple energy storage units, the master controller is used to implement the following functions:

[0102] Obtain the charge and discharge power of the energy storage system at the current moment; determine the operation flag of the energy storage system at the current moment according to the charge and discharge power of the energy storage system; determine the average state of charge of the energy storage system at the current moment according to multiple state of charge sequences corresponding to multiple lithium batteries contained in multiple energy storage units within the specific time period sent by multiple sub-controllers; send the average state of charge and the operation flag of the energy storage system at the current moment to each sub-controller.

[0103] Specifically, the general controller determines the average state of charge of the energy storage system at the current moment according to the multiple state of charge sequences corresponding to the multiple lithium batteries contained in the multiple energy storage units in the specific time period sent by the multiple sub-controllers. The corresponding implementation process may include but is not limited to the following:

[0104] First, for the charge state sequence of each lithium battery in the specific time period, the main controller samples the charge state sequence of the lithium battery according to a preset sampling period, and then averages all the sampled charge states of the lithium battery to obtain the average charge state of the lithium battery; secondly, the main controller averages multiple average charge states corresponding to multiple lithium batteries in the specific time period to obtain the average charge state of the energy storage system at the current moment.

[0105] It should be noted that each sub-controller preferably uses a low-bandwidth communication link to communicate with the main controller to achieve information transmission between each sub-controller and the main controller.

[0106] It should be noted that by introducing the Thevenin equivalent voltage source into the DC microgrid to collect the remaining power sources on the DC microgrid, when the DC microgrid operates in island mode, the energy storage system is mainly responsible for regulating the main DC bus of the DC microgrid, and when the DC microgrid operates in grid-connected mode, the Thevenin equivalent voltage source will assist the energy storage system in voltage regulation.

[0107] It can be understood that the contents of the above method embodiments are all applicable to the present device embodiments, the functions specifically implemented by the present device embodiments are the same as those of the above method embodiments, and the beneficial effects achieved are also the same as those achieved by the above method embodiments.

[0108] The embodiment of the present application also provides an electronic device, which includes a memory and a processor, wherein the memory stores a computer program, and the processor implements the above-mentioned energy storage control method applied to a DC microgrid when executing the computer program. The electronic device may include any intelligent terminal such as a tablet computer and a vehicle-mounted computer.

[0109] It can be understood that the contents of the above method embodiments are all applicable to the present device embodiments, the functions specifically implemented by the present device embodiments are the same as those of the above method embodiments, and the beneficial effects achieved are also the same as those achieved by the above method embodiments.

[0110] See also Figure 3 , Figure 3 The hardware structure of an electronic device according to another embodiment is shown. The electronic device includes:

[0111] The processor 801 may be implemented by a general-purpose CPU (Central Processing Unit), a microprocessor, an application-specific integrated circuit (ASIC), or one or more integrated circuits, and is used to execute relevant programs to implement the technical solutions provided in the embodiments of the present application;

[0112] The memory 802 can be implemented in the form of a read-only memory (ROM), a static storage device, a dynamic storage device, or a random access memory (RAM). The memory 802 can store an operating system and other application programs. When the technical solution provided in the embodiment of the present application is implemented by software or firmware, the relevant program code is stored in the memory 802, and the processor 801 calls and executes the technical solution provided in the embodiment of the present application;

[0113] Input / output interface 803, used to implement information input and output;

[0114] The communication interface 804 is used to realize the communication interaction between the device and other devices. The communication can be realized through a wired manner (such as USB, network cable, etc.) or a wireless manner (such as mobile network, WIFI, Bluetooth, etc.);

[0115] A bus 805 that transmits information between the various components of the device (e.g., the processor 801, the memory 802, the input / output interface 803, and the communication interface 804);

[0116] The processor 801 , the memory 802 , the input / output interface 803 and the communication interface 804 are connected to each other in communication within the device via a bus 805 .

[0117] An embodiment of the present application also provides a computer-readable storage medium, which stores a computer program. When the computer program is executed by a processor, the above-mentioned energy storage control method applied to a DC microgrid is implemented.

[0118] It can be understood that the contents of the above method embodiments are all applicable to the present storage medium embodiments, the functions specifically implemented by the present storage medium embodiments are the same as those of the above method embodiments, and the beneficial effects achieved are also the same as those achieved by the above method embodiments.

[0119] The memory, as a non-transient computer-readable storage medium, can be used to store non-transient software programs and non-transient computer executable programs. In addition, the memory may include a high-speed random access memory, and may also include a non-transient memory, such as at least one disk storage device, a flash memory device, or other non-transient solid-state storage device. In some embodiments, the memory may optionally include a memory remotely disposed relative to the processor, and these remote memories may be connected to the processor via a network. Examples of the above-mentioned network include, but are not limited to, the Internet, an intranet, a local area network, a mobile communication network, and combinations thereof.

[0120] The embodiments described in the embodiments of the present application are intended to more clearly illustrate the technical solutions of the embodiments of the present application and do not constitute a limitation on the technical solutions provided in the embodiments of the present application. Those skilled in the art will appreciate that with the evolution of technology and the emergence of new application scenarios, the technical solutions provided in the embodiments of the present application are also applicable to similar technical problems.

[0121] Those skilled in the art will appreciate that the technical solutions shown in the figures do not constitute a limitation on the embodiments of the present application, and may include more or fewer steps than shown in the figures, or a combination of certain steps, or different steps.

[0122] The system embodiments described above are merely illustrative, and the units described as separate components may or may not be physically separated, that is, they may be located in one place or distributed on multiple network units. Some or all of the modules may be selected according to actual needs to achieve the purpose of the present embodiment.

[0123] Those skilled in the art will appreciate that all or some of the steps in the methods disclosed above, and the functional modules / units in the systems and devices may be implemented as software, firmware, hardware, or a suitable combination thereof.

[0124] The terms "first", "second", "third", "fourth", etc. (if any) in the specification of the present application and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchangeable where appropriate, so that the embodiments of the present application described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any of their variations are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device comprising a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0125] It should be understood that in the present application, "at least one (item)" means one or more, and "plurality" means two or more. "And / or" is used to describe the association relationship of associated objects, indicating that three relationships may exist. For example, "A and / or B" can mean: only A exists, only B exists, and A and B exist at the same time, where A and B can be singular or plural. The character " / " generally indicates that the objects associated before and after are in an "or" relationship. "At least one of the following" or similar expressions refers to any combination of these items, including any combination of single or plural items. For example, at least one of a, b or c can mean: a, b, c, "a and b", "a and c", "b and c", or "a and b and c", where a, b, c can be single or multiple.

[0126] In the several embodiments provided in the present application, it should be understood that the disclosed systems and methods can be implemented in other ways. For example, the system embodiments described above are only schematic. For example, the division of the above units is only a logical function division. There may be other division methods in actual implementation, such as multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be through some interfaces, indirect coupling or communication connection of systems or units, which can be electrical, mechanical or other forms.

[0127] The units described above as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed on multiple network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0128] In addition, each functional unit in each embodiment of the present application may be integrated into one processing unit, or each unit may exist physically separately, or two or more units may be integrated into one unit. The above-mentioned integrated unit may be implemented in the form of hardware or in the form of software functional units.

[0129] If the integrated unit is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present application, or the part that contributes to the prior art, or all or part of the technical solution can be embodied in the form of a software product, and the computer software product is stored in a storage medium, including multiple instructions to enable a computer device (which can be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods of various embodiments of the present application. The aforementioned storage medium includes: U disk, mobile hard disk, read-only memory (Read-Only Memory, referred to as ROM), random access memory (Random Access Memory, referred to as RAM), disk or optical disk and other media that can store programs.

[0130] The preferred embodiments of the present invention are described above with reference to the accompanying drawings, but the scope of the rights of the present invention is not limited thereto. Any modification, equivalent substitution and improvement made by a person skilled in the art without departing from the scope and essence of the present invention should be within the scope of the rights of the present invention.

Claims

1. A method for controlling energy storage applied to a DC microgrid, wherein the energy storage system of the DC microgrid comprises a plurality of energy storage units, characterized in that: The method comprises: For each of the energy storage units, the energy storage unit includes a lithium battery and a DC converter, obtaining the output current of the lithium battery, the output current and output voltage of the DC converter, and the operation flag and average charge state of the energy storage system at the current moment; Determining a current reference signal according to an operation flag of the energy storage system; Correcting a preset bus voltage given value according to the output current of the DC converter, the operation flag and the average state of charge of the energy storage system, and the predetermined state of charge of the lithium battery at the current moment; The operating state of the DC converter is adjusted according to the output current of the lithium battery, the output voltage of the DC converter, the current reference signal and the corrected bus voltage given value.

2. The energy storage control method applied to a DC microgrid according to claim 1, characterized in that: The state of charge of the lithium battery at the current moment is obtained by: Obtaining the initial state of charge of the lithium battery at a historical moment and the output current sequence of the lithium battery in a specific time period, wherein the specific time period is a time period from the next moment of the historical moment to the current moment; According to the initial state of charge, output current sequence, rated capacity and charge and discharge efficiency of the lithium battery, the state of charge sequence of the lithium battery in the specific time period is determined, and then the state of charge of the lithium battery at the current moment is extracted therefrom.

3. The energy storage control method applied to a DC microgrid according to claim 1, characterized in that: Determining the current reference signal according to the operation flag of the energy storage system includes: When the operation flag of the energy storage system is a charging flag, obtaining the terminal voltage of the lithium battery at the current moment; The current reference signal is determined according to the terminal voltage of the lithium battery and a preset expected voltage of the lithium battery after being fully charged.

4. The energy storage control method applied to a DC microgrid according to claim 1, characterized in that: Determining the current reference signal according to the operation flag of the energy storage system includes: When the operation flag of the energy storage system is a discharge flag, the current reference signal is determined according to the output voltage of the DC converter and the given value of the bus voltage.

5. The energy storage control method applied to a DC microgrid according to claim 1, characterized in that: The step of correcting the preset bus voltage given value according to the output current of the DC converter, the operation flag and the average state of charge of the energy storage system, and the predetermined state of charge of the lithium battery at the current moment includes: Determining a droop compensation voltage according to the output current of the DC converter, the operation flag and the average state of charge of the energy storage system, the state of charge of the lithium battery and a preset droop resistance; The bus voltage given value is corrected according to the droop compensation voltage.

6. The energy storage control method applied to a DC microgrid according to claim 1, characterized in that: The step of adjusting the operating state of the DC converter according to the output current of the lithium battery, the output voltage of the DC converter, the current reference signal and the corrected bus voltage given value includes: Determining a first current reference signal according to the output voltage of the DC converter and the corrected bus voltage given value; Determining a voltage control signal according to the output current of the lithium battery, the current reference signal and the first current reference signal; The output power of the DC converter is adjusted according to the voltage control signal.

7. An energy storage control device applied to a DC microgrid, wherein the energy storage system of the DC microgrid comprises a plurality of energy storage units, characterized in that: The device comprises a plurality of sub-controllers configured corresponding to the plurality of energy storage units; For each of the energy storage units, the energy storage unit includes a lithium battery and a DC converter, and the sub-controller configured for the energy storage unit is used to: obtain the output current of the lithium battery, the output current and output voltage of the DC converter at the current moment, and the operation flag and average charge state of the energy storage system; Determining a current reference signal according to an operation flag of the energy storage system; The preset bus voltage given value is corrected according to the output current of the DC converter, the operation flag and the average charge state of the energy storage system and the predetermined charge state of the lithium battery at the current moment; the operation state of the DC converter is adjusted according to the output current of the lithium battery, the output voltage of the DC converter, the current reference signal and the corrected bus voltage given value.

8. The energy storage control device for DC microgrid according to claim 7, characterized in that: The device also includes a master controller configured for the energy storage system; The sub-controller configured for the energy storage unit is also used to generate a state of charge sequence of the lithium battery in a specific time period and send it to the main controller, wherein the specific time period includes the current moment; The main controller is used to: obtain the charging and discharging power of the energy storage system at the current moment; determine the operation flag of the energy storage system at the current moment according to the charging and discharging power of the energy storage system; determine the average state of charge of the energy storage system at the current moment according to the multiple state of charge sequences corresponding to the multiple lithium batteries contained in the multiple energy storage units within the specific time period sent by the multiple sub-controllers; and send the operation flag and the average state of charge of the energy storage system at the current moment to each of the sub-controllers.

9. An electronic device, characterized in that: The electronic device comprises a memory and a processor, the memory stores a computer program, and the processor implements the method according to any one of claims 1 to 6 when executing the computer program.

10. A computer-readable storage medium storing a computer program, characterized in that: When the computer program is executed by a processor, the method according to any one of claims 1 to 6 is implemented.

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