CN113097992A - Droop control method and device for direct-current micro-grid and computer storage medium - Google Patents

Droop control method and device for direct-current micro-grid and computer storage medium Download PDF

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CN113097992A
CN113097992A CN202110469819.2A CN202110469819A CN113097992A CN 113097992 A CN113097992 A CN 113097992A CN 202110469819 A CN202110469819 A CN 202110469819A CN 113097992 A CN113097992 A CN 113097992A
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energy storage
storage unit
value
current
soc
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CN113097992B (en
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文小玲
王佳
杨颖�
舒李俊
周勇
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Wuhan Institute of Technology
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    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J1/00—Circuit arrangements for dc mains or dc distribution networks
    • H02J1/10—Parallel operation of dc sources
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J7/00—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries
    • H02J7/0029—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries with safety or protection devices or circuits
    • H02J7/00302—Overcharge protection
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J7/00—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries
    • H02J7/0029—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries with safety or protection devices or circuits
    • H02J7/00306—Overdischarge protection
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J7/00—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries
    • H02J7/0047—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries with monitoring or indicating devices or circuits
    • H02J7/0048—Detection of remaining charge capacity or state of charge [SOC]
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J7/00—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries
    • H02J7/007—Regulation of charging or discharging current or voltage
    • H02J7/00712—Regulation of charging or discharging current or voltage the cycle being controlled or terminated in response to electric parameters

Abstract

The invention relates to a droop control method, a droop control device and a computer storage medium for a direct-current micro-grid, wherein the droop control method for the direct-current micro-grid comprises the following steps: acquiring a first output current value of a converter corresponding to a current energy storage unit in real time, and acquiring a first charge state value of the current energy storage unit at the same time; calculating to obtain a first droop coefficient corresponding to the current energy storage unit according to the first output current value and the first state of charge value; carrying out droop control on the current energy storage unit according to the first droop coefficient; and respectively calculating a corresponding first droop coefficient for each energy storage unit of the direct current micro-grid by adopting the steps, and performing droop control. By means of the method, the size of the droop coefficient is changed in real time according to the charge state value of the current energy storage unit, so that the charge state values of the energy storage units are balanced, and the problems of over-charge and over-discharge of the energy storage units and unbalance of the charge state values are avoided.

Description

Droop control method and device for direct-current micro-grid and computer storage medium
Technical Field
The invention relates to the technical field of direct-current micro-grid energy storage, in particular to a droop control method and device for a direct-current micro-grid and a computer storage medium.
Background
In recent years, the concept of a direct current micro-grid is proposed, and the direct current micro-grid consists of a distributed power supply such as a photovoltaic power supply and a fan, an energy storage system, an alternating current load, a direct current load, a converter connected with an alternating current grid and a control system. The direct-current micro-grid only has a balance relation between direct-current bus voltage and active power, and the fluctuation condition of the bus voltage reflects the power balance relation in the system, so that the aim of inhibiting the bus fluctuation is fulfilled by applying reasonable control on an energy storage system. The power distribution method of the energy storage units connected in parallel generally adopts droop control, and the droop control is simple in control structure, does not depend on interconnection communication among the energy storage units, is high in reliability and is widely applied. However, the droop coefficient of the droop control is fixed after being determined, and when the droop control is adopted to adjust the converter at the interface of the energy storage unit, the fixed droop coefficient brings certain problems, and when the energy storage element in the energy storage unit, such as a storage battery, is excessively charged or discharged, the service life of the battery is reduced, and the deep discharge can cause the direct paralysis of the storage battery. The traditional droop control method does not have the capability of adjusting the droop coefficient in real time according to the state of charge (SOC) of the energy storage unit, the single charging speed may cause the energy storage unit with high SOC to be overcharged, and the same single discharging speed may cause the energy storage unit with low SOC to be overdischarged and the electric quantity of other energy storage units cannot be fully utilized. Therefore, when the energy storage units are connected in parallel for charging and discharging, the problems of overcharge and overdischarge of the energy storage units and unbalanced charged state values may occur when the existing droop control is adopted.
Disclosure of Invention
In order to solve the problems that an energy storage unit of a direct current micro-grid is overcharged and overdischarged and the state of charge value is unbalanced due to an existing droop control method, the invention provides a droop control method and device for the direct current micro-grid and a computer storage medium.
In a first aspect, to solve the above technical problem, the present invention provides a droop control method for a dc micro grid, including:
acquiring a first output current value of a converter corresponding to a current energy storage unit in real time, and acquiring a first charge state value of the current energy storage unit at the same time;
calculating to obtain a first droop coefficient corresponding to the current energy storage unit according to the first output current value and the first state of charge value;
carrying out droop control on the current energy storage unit according to the first droop coefficient;
and respectively calculating a corresponding first droop coefficient for each energy storage unit of the direct current micro-grid by adopting the steps, and performing droop control.
The invention has the beneficial effects that: and changing the size of the droop coefficient in real time according to the charge state value of the current energy storage unit, and finally enabling the charge state values of the energy storage units to tend to be balanced to realize overcharge and overdischarge protection.
On the basis of the technical scheme, the invention can be further improved as follows.
Further, the calculating process of the first droop coefficient includes:
according to the formula
Figure BDA0003044926620000021
Calculating to obtain an adjusting factor diWherein, sociIs the first state of charge value, socAIs the average charge state value of all energy storage units of the direct current micro-grid, n is a preset control parameter, idciIs the first output current value;
according to the formula R (soc)i)＝R0*diAnd calculating to obtain the first sag coefficient R (soc)i) Wherein R is0A preset initial droop coefficient, d, corresponding to the current energy storage unitiIs the regulatory factor.
The beneficial effect who adopts above-mentioned improvement scheme is: by adjusting the adjustment factor diThe preset control parameter n in (1) is,the equalization speed of the state of charge value can be controlled, and the equalization speed of the state of charge value can be increased by increasing the preset control parameter n.
Further, the first sag factor R (soc)i) Satisfy the requirement of
Figure BDA0003044926620000031
Wherein, Δ udcmaxAllowing the maximum fluctuation range value i of the DC bus voltage of the DC micro-griddcmaxAnd the maximum allowable output current value of the converter corresponding to the current energy storage unit is obtained.
The beneficial effect who adopts above-mentioned improvement scheme is: further ensuring the normal work of the direct current micro-grid, and avoiding the first droop coefficient R (soc) caused by excessively increasing the preset control parameter ni) The selection of the voltage exceeds the allowable dropping range of the direct current bus voltage, so that the whole direct current micro-grid system loses stability.
Further, the average state of charge value socAThe calculation process of (2) includes:
according to the formula
Figure BDA0003044926620000032
Calculating to obtain the average state of charge value socAWherein, socjThe number is the charge state value of the energy storage unit with the serial number j, and N is the total number of all the energy storage units of the direct current micro-grid.
The beneficial effect who adopts above-mentioned improvement scheme is: the droop coefficient is combined with the charge state values of all the energy storage units, so that the droop coefficient is reasonably changed, the charge state values of the energy storage units are balanced, the over-charge and over-discharge of the energy storage units are avoided, and the method is easy to realize.
Further, before the first droop coefficient corresponding to the current energy storage unit is obtained through calculation according to the first output current value and the first state of charge value, the method further includes:
judging a first state of charge value soc of the current energy storage unitiWhether the soc is more than or equal to 20 percentiLess than or equal to 80 percent to obtain a first judgment result;
and when the first judgment result is negative, stopping performing droop control on the current energy storage unit, performing charging/discharging treatment until the current energy storage unit meets a preset condition, stopping the charging/discharging treatment, and performing droop control on the current energy storage unit again.
The beneficial effect who adopts above-mentioned improvement scheme is: and each energy storage unit is processed according to the charge state value, so that the working stability of the direct-current micro-grid is further improved.
Further, the preset conditions are the current real-time state of charge value soc of the energy storage unit and the real-time average state of charge value of all the energy storage units of the direct current microgrid
Figure BDA0003044926620000041
Equal to, wherein sockThe real-time charge state value of the energy storage unit with the serial number k is shown, and N is the total number of all the energy storage units of the direct-current micro-grid.
The beneficial effect who adopts above-mentioned improvement scheme is: the energy storage units with the charge state values not within the range of 20% to 80% do not adopt droop control, but the energy storage units are subjected to droop control when the charge state values of the energy storage units are adjusted to the average charge state values of all the energy storage units by using charge and discharge processing, so that the system stability of a direct-current micro-grid is ensured, the charge state values of the energy storage units tend to be balanced, and overcharge and overdischarge protection is realized.
Further, the current energy storage unit is a storage battery pack, and the first state of charge value sociThe calculation process of (2) includes:
according to the formula
Figure BDA0003044926620000042
Calculating to obtain the first state of charge value sociWherein, CbatIs the cell capacity of the battery pack, iLIs the output current value of the battery pack, soci0And the initial state of charge value of the storage battery pack is obtained.
The beneficial effect who adopts above-mentioned improvement scheme is: and the state of charge value of the storage battery pack is calculated according to the output current value of the storage battery pack obtained by sampling, and the calculation is simple and easy to realize.
In a second aspect, the invention provides a droop control device for a direct-current micro-grid, which comprises an acquisition module, a calculation module and a control module;
the acquisition module is used for acquiring a first output current value of a converter corresponding to the current energy storage unit in real time and acquiring a first charge state value of the current energy storage unit at the same time;
the calculation module is used for calculating and obtaining a first droop coefficient corresponding to the current energy storage unit according to the first output current value and the first state of charge value;
and the control module is used for carrying out droop control on the current energy storage unit according to the first droop coefficient.
Further, the computing module comprises a first computing module and a second computing module;
the first calculation module is used for calculating according to a formula
Figure BDA0003044926620000051
Calculating to obtain an adjusting factor diWherein, sociIs the first state of charge value, socAIs the average charge state value of all energy storage units of the direct current micro-grid, n is a preset control parameter, idciIs the first output current value;
the second calculation module is used for calculating the formula R (soc)i)＝R0*diAnd calculating to obtain the first sag coefficient R (soc)i) Wherein R is0A preset initial droop coefficient, d, corresponding to the current energy storage unitiIs the regulatory factor.
In a third aspect, the present invention further provides a computer-readable storage medium, where instructions are stored, and when the instructions are executed on a terminal device, the terminal device is caused to execute any one of the above-mentioned droop control methods for a dc microgrid.
Drawings
Fig. 1 is a schematic flowchart of a droop control method for a dc microgrid according to an embodiment of the present invention;
fig. 2 is a schematic circuit diagram of a parallel battery pack in a dc micro-grid according to an embodiment of the present invention;
fig. 3 is a schematic structural diagram of a droop control apparatus for a dc microgrid according to an embodiment of the present invention;
fig. 4 is a schematic structural diagram of a droop control apparatus for a dc microgrid according to another embodiment of the present invention.
Detailed Description
The following examples are further illustrative and supplementary to the present invention and do not limit the present invention in any way.
A droop control method for a dc microgrid according to an embodiment of the present invention is described below with reference to the accompanying drawings.
Referring to fig. 1, the present invention provides a droop control method for a dc microgrid, including:
s1, acquiring a first output current value of a converter corresponding to the current energy storage unit in real time, and acquiring a first state of charge value of the current energy storage unit at the same time;
s2, calculating to obtain a first droop coefficient corresponding to the current energy storage unit according to the first output current value and the first state of charge value;
s3, carrying out droop control on the current energy storage unit according to the first droop coefficient;
and S4, calculating a corresponding first droop coefficient for each energy storage unit of the direct current microgrid by adopting the steps, and performing droop control.
According to the droop control method for the direct-current micro-grid, the droop coefficient and the charge state value of the energy storage unit are combined, the magnitude of the droop coefficient is changed in real time according to the current charge state value of the energy storage unit, and finally the charge state value of the energy storage unit tends to be balanced, so that the problems of over-charge and over-discharge of the energy storage unit and unbalance of the charge state value are solved.
It can be understood that a plurality of energy storage units may be provided in the energy storage system of the dc microgrid, the plurality of energy storage units are respectively connected in parallel to a dc bus of the dc microgrid through a converter, and the energy storage units may be energy storage elements such as a storage battery or a storage battery pack.
Specifically, in this embodiment, in order to promote the balance of the soc values of the energy storage units, the calculated first droop coefficient should be such that the energy storage units with high soc values absorb less electric quantity and the energy storage units with low soc values absorb more electric quantity during the charging process; in the discharging process, the energy storage unit with a high charge state value releases more electric quantity, and the energy storage unit with a low charge state value releases less electric quantity, so that the charge state values of the energy storage units are balanced.
Preferably, the calculation process of the first droop coefficient includes:
according to the formula
Figure BDA0003044926620000071
Calculating to obtain an adjusting factor diWherein, sociIs the first state of charge value, socAIs the average charge state value of all energy storage units of the direct current micro-grid, n is a preset control parameter, idciIs the first output current value;
according to the formula R (soc)i)＝R0*diAnd calculating to obtain the first sag coefficient R (soc)i) Wherein R is0A preset initial droop coefficient, d, corresponding to the current energy storage unitiIs the regulatory factor.
In this embodiment, the adjustment factor d is adjustediThe preset control parameter n in (1) can control the equalization speed of the state of charge value, so that the equalization speed of the state of charge value can be increased by increasing the preset control parameter n.
Further, the average state of charge value socAThe calculation process of (2) includes:
according to the formula
Figure BDA0003044926620000072
Calculating to obtain the average state of charge value socAWherein, socjThe number is the charge state value of the energy storage unit with the serial number j, and N is the total number of all the energy storage units of the direct current micro-grid.
It is understood that the calculation of the droop coefficient should be divided into two cases, the charge and discharge states. i.e. idciIf the energy storage unit is in the discharge state if the charge state value of the energy storage unit is greater than the average value, for example soci＞socAThen, the first sag factor R (soc) calculated at this time is knowni)＜R0I.e. compared to a predetermined initial sag factor R0If the value of the state of charge is smaller than the average value, the energy storage unit will provide a smaller load current than if no adjustment factor is added; when i isdciIf the charge state value of the energy storage unit is larger than the average value at the moment, the soc isi＞socAThen there is R (soc)i)＞R0The energy storage unit will absorb a smaller load current than without the addition of the adjustment factor, thus knowing that if the state of charge value is less than the average value, the energy storage unit will absorb a larger load current than without the addition of the adjustment factor.
Therefore, the droop coefficient calculated by the adjusting factor can realize the charge state value balance and the overcharge and over-discharge protection of the energy storage unit.
Optionally, in one embodiment, the first sag factor R (soc)i) Satisfy the requirement of
Figure BDA0003044926620000081
Wherein, Δ udcmaxAllowing the maximum fluctuation range value i of the DC bus voltage of the DC micro-griddcmaxAnd the maximum allowable output current value of the converter corresponding to the current energy storage unit is obtained.
It is to be noted thatIn the droop control, the calculated droop coefficient R (soc)i) If the value is too large, the deviation between the bus voltage and the actual reference value is possibly large, so that the whole direct-current micro-grid system is unstable, and therefore the corresponding droop coefficient selection rule is as follows in the discharge state:
Figure BDA0003044926620000082
the charging state is as follows:
Figure BDA0003044926620000083
wherein R is0And setting the initial droop coefficient for the preset initial droop coefficient.
Further, in an embodiment, before the calculating, according to the first output current value and the first state of charge value, a first droop coefficient corresponding to the current energy storage unit, the method further includes:
judging a first state of charge value soc of the current energy storage unitiWhether the soc is more than or equal to 20 percentiLess than or equal to 80 percent to obtain a first judgment result;
and when the first judgment result is negative, stopping performing droop control on the current energy storage unit, performing charging/discharging treatment until the current energy storage unit meets a preset condition, stopping the charging/discharging treatment, and performing droop control on the current energy storage unit again.
Preferably, the preset conditions are the current real-time state of charge value soc of the energy storage unit and the real-time average state of charge value of all energy storage units of the direct current microgrid
Figure BDA0003044926620000084
Equal to, wherein sockThe real-time charge state value of the energy storage unit with the serial number k is shown, and N is the total number of all the energy storage units of the direct-current micro-grid.
It should be noted that, the optimal applicable condition of the droop control method is that when the state of charge value of the energy storage unit is within the range of 20% to 80%, when there is an energy storage unit with a state of charge value greater than 80%, the energy storage unit should be prohibited from charging, and only allowed to operate in a discharging state, that is, the energy storage unit is subjected to discharging processing; when the energy storage units with the state of charge values smaller than 20% exist, the energy storage units are forbidden to discharge, the energy storage units are only allowed to work in a charging state, namely, the energy storage units are charged, the energy storage units which are charged/discharged are not subjected to the droop control method, and the energy storage units are subjected to the droop control method until the state of charge values of the energy storage units are adjusted to the average state of charge of all the current energy storage units, and are synchronously charged and discharged with other energy storage units.
Further, in one embodiment, the current energy storage unit is a battery pack, and the first state of charge value sociThe calculation process of (2) includes:
according to the formula
Figure BDA0003044926620000091
Calculating to obtain the first state of charge value sociWherein, CbatIs the cell capacity of the battery pack, iLIs the output current value of the battery pack, soci0And the initial state of charge value of the storage battery pack is obtained.
Specifically, in this embodiment, the battery packs may be connected in parallel to the DC bus via a bidirectional DC/DC converter (bidirectional DC-DC converter).
For example, in one embodiment, referring to fig. 2, the battery pack 1 and the battery pack 2 are respectively connected in parallel to a dc bus through a converter to supply power to a load; u. ofbat1、ubat2Output voltage of the storage battery pack 1 and output voltage of the storage battery pack 2, iL1、iL2Output currents, S, of the battery pack 1 and the battery pack 2, respectively1、S2、S3、S4Is IGBT (insulated gate bipolar transistor), R is load resistance, wherein, the inductance L1Insulated gate bipolar transistor S1And S2And a capacitor C1A converter 1 corresponding to the storage battery 1, an inductor L2Insulated gate bipolar transistor S3And S4And a capacitor C2Constituting a converter 2, u corresponding to said battery pack 2dc1、udc2Output voltages, i, of converters 1 and 2, respectivelydc1、idc2Respectively outputting current for converter 1 and converter 2;
further, in this embodiment, for the battery pack 1, the output current value i of the inverter 1 is detected firstdc1And calculating the current state of charge value soc of the storage battery pack 11，soc1The calculation formula of (2) is as follows:
Figure BDA0003044926620000092
wherein, Cbat1Is the cell capacity, soc, of the battery pack 110Simultaneously carrying out similar calculation steps on the storage battery pack 2 to obtain a state of charge value soc for the initial state of charge value of the storage battery pack 12(ii) a On calculation of soc1、soc2Post-detection soc1、soc2Whether the battery pack is in the range of 20% to 80%, when the battery pack with the state of charge value larger than 80% exists in the parallel battery packs, the charging of the battery pack is forbidden, and the battery pack is only allowed to work in a discharging state; when the state of charge value in the storage battery pack is less than 20%, the storage battery pack should be prohibited from discharging, and only the storage battery pack should be allowed to work in a charging state, and the discharging and charging modes of the storage battery pack in the two cases do not adopt the droop control method, and a traditional charging and discharging mode can be adopted. When the state of charge value of the storage battery pack is adjusted to the average state of charge value of the storage battery, the storage battery pack and other storage battery packs are charged and discharged together;
if soc1、soc2Within the range of 20% to 80%, the soc is first calculatedAThe calculation formula is
Figure BDA0003044926620000101
When N is 2;
at the same time, i for battery packs 1 and 2, respectivelydc1、idc2Judging the positive and negative of the signal; for the battery pack 1, when idc1> 0, the battery pack 1 is in dischargeStatus, then factor d is adjusted1Comprises the following steps:
Figure BDA0003044926620000102
when i isdc1If < 0, the storage battery pack 1 is in a charging state, the factor d is adjusted1Comprises the following steps:
Figure BDA0003044926620000103
performing similar calculation steps on the storage battery pack 2 to obtain an adjusting factor d2The balance of the state of charge values can be accelerated by adjusting a preset control parameter n in the adjustment factor, but the adjustment factor is in a range of bus voltage allowed to drop;
finally by the formula R (soc)1)＝R01*d1、R(soc2)＝R02*d2To obtain the adjusted sag factor R (soc) of the battery packs 1 and 21)、R(soc2) So that the charge states of the storage battery packs 1 and 2 tend to be balanced and overcharge and overdischarge are avoided, wherein R01、R02The preset initial droop coefficients corresponding to the storage battery pack 1 and the storage battery pack 2 are respectively; further, the droop control method is adopted for the storage battery pack 1 and the storage battery pack 2, and specifically, the relevant parameters of the corresponding converters are adjusted according to the adjusted droop coefficients, so that the outputs of the two storage battery packs meet a droop formula: u. ofdc1＝udcref-idc1R(soc1)、udc2＝udcref-idc2R(soc2) And
Figure BDA0003044926620000111
wherein u isdcrefIs a direct current bus reference voltage.
The droop control method for the direct-current microgrid is simple and easy to understand and realize, and has a good application prospect.
In the above embodiments, although the steps are numbered as S1, S2, etc., but only the specific embodiments are given in this application, a person skilled in the art may adjust the execution sequence of S1, S2, etc. according to the actual situation, and this is within the scope of the present invention, and it is understood that some embodiments may include some or all of the above embodiments.
As shown in fig. 3, a droop control apparatus 10 for a dc microgrid according to an embodiment of the present invention includes an acquisition module 20, a calculation module 30, and a control module 40;
the acquisition module 20 is configured to acquire a first output current value of a converter corresponding to a current energy storage unit in real time, and acquire a first state of charge value of the current energy storage unit at the same time;
the calculating module 30 is configured to calculate and obtain a first droop coefficient corresponding to the current energy storage unit according to the first output current value and the first state of charge value;
and the control module 40 is configured to perform droop control on the current energy storage unit according to the first droop coefficient.
Optionally, in one embodiment, the calculation module 30 includes a first calculation module and a second calculation module;
the first calculation module is used for calculating according to a formula
Figure BDA0003044926620000121
Calculating to obtain an adjusting factor diWherein, sociIs the first state of charge value, socAIs the average charge state value of all energy storage units of the direct current micro-grid, n is a preset control parameter, idciIs the first output current value;
the second calculation module is used for calculating the formula R (soc)i)＝R0*diAnd calculating to obtain the first sag coefficient R (soc)i) Wherein R is0A preset initial droop coefficient, d, corresponding to the current energy storage unitiIs the regulatory factor.
Preferably, said first sag factor R (soc)i) Satisfy the requirement of
Figure BDA0003044926620000122
Wherein, Δ udcmaxAllowing the maximum fluctuation range value i of the DC bus voltage of the DC micro-griddcmaxAnd the maximum allowable output current value of the converter corresponding to the current energy storage unit is obtained.
Optionally, in one embodiment, the calculation module 30 further includes a third calculation module; the third calculation module is used for calculating according to a formula
Figure BDA0003044926620000123
Calculating to obtain the average state of charge value socAWherein, socjThe number is the charge state value of the energy storage unit with the serial number j, and N is the total number of all the energy storage units of the direct current micro-grid.
Optionally, in an embodiment, referring to fig. 4, the energy storage system further includes a determining module 50, where the determining module 50 is configured to determine the first state of charge value soc of the current energy storage unitiWhether the soc is more than or equal to 20 percentiLess than or equal to 80 percent to obtain a first judgment result; and when the first judgment result is negative, stopping performing droop control on the current energy storage unit, performing charging/discharging treatment until the current energy storage unit meets a preset condition, stopping the charging/discharging treatment, and performing droop control on the current energy storage unit again.
Preferably, the preset conditions are the current real-time state of charge value soc of the energy storage unit and the real-time average state of charge value of all energy storage units of the direct current microgrid
Figure BDA0003044926620000131
Equal to, wherein sockThe real-time charge state value of the energy storage unit with the serial number k is shown, and N is the total number of all the energy storage units of the direct-current micro-grid.
OptionalIn one embodiment, the current energy storage unit is a battery pack, and the acquisition module 20 is specifically configured to perform the following operations according to a formula
Figure BDA0003044926620000132
Calculating to obtain the first state of charge value sociWherein, CbatIs the cell capacity of the battery pack, iLIs the output current value of the battery pack, soci0And the initial state of charge value of the storage battery pack is obtained.
An embodiment of the present invention further provides a computer-readable storage medium, where instructions are stored in the computer-readable storage medium, and when the instructions are executed on a terminal device, the terminal device is enabled to execute the parameters and the steps in the foregoing embodiment of the droop control method for the dc microgrid, which are not described herein again.
As will be appreciated by one skilled in the art, the present invention may be embodied as an apparatus, method or computer program product. Accordingly, the present disclosure may be embodied in the form of: may be embodied entirely in hardware, entirely in software (including firmware, resident software, micro-code, etc.) and in a combination of hardware and software, and may be referred to herein generally as a "circuit," module "or" device. Furthermore, in some embodiments, the invention may also be embodied in the form of a computer program product in one or more computer-readable media having computer-readable program code embodied in the medium.
In the description herein, references to the description of the term "one embodiment," "some embodiments," "an example," "a specific example," or "some examples," etc., mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, the schematic representations of the terms used above are not necessarily intended to refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples. Furthermore, various embodiments or examples and features of different embodiments or examples described in this specification can be combined and combined by one skilled in the art without contradiction.
Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention, and that variations, modifications, substitutions and alterations can be made to the above embodiments by those of ordinary skill in the art within the scope of the present invention.

Claims (10)

1. A droop control method for a direct current micro-grid is characterized by comprising the following steps:
acquiring a first output current value of a converter corresponding to a current energy storage unit in real time, and acquiring a first charge state value of the current energy storage unit at the same time;
calculating to obtain a first droop coefficient corresponding to the current energy storage unit according to the first output current value and the first state of charge value;
carrying out droop control on the current energy storage unit according to the first droop coefficient;
and respectively calculating a corresponding first droop coefficient for each energy storage unit of the direct current micro-grid by adopting the steps, and performing droop control.
2. The droop control method for the direct-current micro-grid according to claim 1, wherein the calculation process of the first droop coefficient comprises:
according to the formula
Figure FDA0003044926610000011
Calculating to obtain an adjusting factor diWherein, sociIs the first state of charge value, socAIs the average charge state value of all energy storage units of the direct current micro-grid, n is a preset control parameter, idciIs the first output current value;
according to the formula R (soc)i)＝R0*diAnd calculating to obtain the first sag coefficient R (soc)i) Wherein R is0A preset initial droop coefficient, d, corresponding to the current energy storage unitiIs the regulatory factor.
3. The droop control method for the direct-current microgrid according to claim 2, characterized in that the first droop coefficient R (soc)i) Satisfy the requirement of
Figure FDA0003044926610000012
Wherein, Δ udcmaxAllowing the maximum fluctuation range value i of the DC bus voltage of the DC micro-griddcmaxAnd the maximum allowable output current value of the converter corresponding to the current energy storage unit is obtained.
4. The droop control method for the direct current microgrid of claim 2, characterized in that the average state of charge value socAThe calculation process of (2) includes:
according to the formula
Figure FDA0003044926610000021
Calculating to obtain the average state of charge value socAWherein, socjThe number is the charge state value of the energy storage unit with the serial number j, and N is the total number of all the energy storage units of the direct current micro-grid.
5. The droop control method for the direct current microgrid according to any one of claims 1 to 4, characterized in that before the first droop coefficient corresponding to the current energy storage unit is calculated and obtained according to the first output current value and the first state of charge value, the method further comprises:
judging a first state of charge value soc of the current energy storage unitiWhether the soc is more than or equal to 20 percentiLess than or equal to 80 percent to obtain a first judgment result;
and when the first judgment result is negative, stopping performing droop control on the current energy storage unit, performing charging/discharging treatment until the current energy storage unit meets a preset condition, stopping the charging/discharging treatment, and performing droop control on the current energy storage unit again.
6. The droop control method for the direct current microgrid according to claim 5, wherein the preset conditions are a real-time state of charge (soc) value of the current energy storage unit and a real-time average soc value of all energy storage units of the direct current microgrid
Figure FDA0003044926610000022
Equal to, wherein sockThe real-time charge state value of the energy storage unit with the serial number k is shown, and N is the total number of all the energy storage units of the direct-current micro-grid.
7. The droop control method for the direct current microgrid according to any one of claims 1 to 4, characterized in that the current energy storage unit is a storage battery, and the first state of charge value sociThe calculation process of (2) includes:
according to the formula
Figure FDA0003044926610000031
Calculating to obtain the first state of charge value sociWherein, CbatIs the cell capacity of the battery pack, iLIs the output current value of the battery pack, soci0And the initial state of charge value of the storage battery pack is obtained.
8. A droop control device for a direct-current micro-grid is characterized by comprising an acquisition module, a calculation module and a control module;
the acquisition module is used for acquiring a first output current value of a converter corresponding to the current energy storage unit in real time and acquiring a first charge state value of the current energy storage unit at the same time;
the calculation module is used for calculating and obtaining a first droop coefficient corresponding to the current energy storage unit according to the first output current value and the first state of charge value;
and the control module is used for carrying out droop control on the current energy storage unit according to the first droop coefficient.
9. The droop control device for the direct-current microgrid of claim 8, wherein the calculation module comprises a first calculation module and a second calculation module;
the first calculation module is used for calculating according to a formula
Figure FDA0003044926610000032
Calculating to obtain an adjusting factor diWherein, sociIs the first state of charge value, socAIs the average charge state value of all energy storage units of the direct current micro-grid, n is a preset control parameter, idciIs the first output current value;
the second calculation module is used for calculating the formula R (soc)i)＝R0*diAnd calculating to obtain the first sag coefficient R (soc)i) Wherein R is0A preset initial droop coefficient, d, corresponding to the current energy storage unitiIs the regulatory factor.
10. A computer-readable storage medium having stored therein instructions that, when run on a terminal device, cause the terminal device to perform the droop control method for a dc microgrid of any of claims 1-7.
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