CN113097992B - Droop control method and device for direct-current micro-grid and computer storage medium - Google Patents

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 microgrid 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, the charge state values of the energy storage units are finally balanced, and the problems of over-charging and over-discharging of the energy storage units and unbalance of the charge state values are avoided.

Description

Droop control method, device and computer storage medium for DC microgrid

technical field

The invention relates to the technical field of direct current microgrid energy storage, and in particular to a droop control method, device and computer storage medium for direct current microgrid.

Background technique

In recent years, people have put forward the concept of DC microgrid, which consists of distributed power sources such as photovoltaics and fans, energy storage systems, AC and DC loads, and converters and control systems connected to the AC grid. There is only a balance relationship between the DC bus voltage and active power in a DC microgrid. The fluctuation of the bus voltage reflects the power balance relationship in the system. Therefore, it is necessary to apply a reasonable control to the energy storage system to suppress the busbar fluctuation. The power distribution method of parallel energy storage units usually adopts droop control, which is widely used because of its simple control structure, high reliability and high reliability because it does not rely on the interconnection and communication between energy storage units. However, the droop coefficient of the droop control will be fixed after it is determined. When the droop control is used to adjust the converter at the interface of the energy storage unit, the fixed droop coefficient will bring certain problems. The energy storage elements in the energy storage unit such as Battery, when the battery is overcharged or discharged, the battery life will be reduced, and the deep discharge will directly paralyze the battery. However, the traditional droop control method does not have the ability to adjust the droop coefficient in real time according to the state of charge (SOC) of the energy storage unit. A single charging speed may lead to overcharging of the energy storage unit with a high SOC. The same single discharging speed may lead to The energy storage unit with low SOC is over-discharged and the power of other energy storage units cannot be fully utilized. Therefore, when the energy storage units are charged and discharged in parallel, the existing droop control may cause the problems of overcharge and overdischarge of the energy storage units and unbalanced state of charge values.

SUMMARY OF THE INVENTION

In order to solve the problems that the existing droop control method will cause overcharge and overdischarge and unbalanced state of charge value of the energy storage unit of the DC microgrid, the present invention provides a droop control method, device and device for the DC microgrid. computer storage media.

In the first aspect, in order to solve the above technical problems, the present invention provides a droop control method for a DC microgrid, including:

acquiring in real time the first output current value of the converter corresponding to the current energy storage unit, and simultaneously acquiring the first state of charge value of the current energy storage unit;

Calculate the first droop coefficient corresponding to the current energy storage unit according to the first output current value and the first state of charge value;

performing droop control on the current energy storage unit according to the first droop coefficient;

The above steps are used to calculate the corresponding first droop coefficient for each energy storage unit of the DC microgrid respectively, and perform droop control.

The beneficial effect of the present invention is that the size of the droop coefficient is changed in real time according to the current state of charge value of the energy storage unit, and finally the state of charge value of each energy storage unit tends to be balanced, thereby realizing overcharge and overdischarge protection.

On the basis of the above technical solutions, the present invention can also be improved as follows.

Further, the calculation process of the first droop coefficient includes:

计算得到调节因子d_i，其中，soc_i为所述第一荷电状态值，soc_A为所述直流微电网的全部储能单元的平均荷电状态值，n为预设控制参数，i_dci为所述第一输出电流值；According to the formula

The adjustment factor d _i is obtained by calculation, where _soci is the first state of charge value, soc _A is the average state of charge value of all energy storage units in the DC microgrid, n is a preset control parameter, and i _dci is the first output current value;

According to the formula R(soci )=R ₀ *d _i , the first droop coefficient R( _{soci )} is obtained by calculation, wherein R ₀ is the preset initial droop coefficient corresponding to the current energy storage unit, d _i is the adjustment factor.

The beneficial effect of adopting the above improvement scheme is: by adjusting the preset control parameter n in the adjustment factor d _i , the equalization speed of the state of charge value can be controlled, and then the load can be increased by increasing the preset control parameter n The electrical state value equalizes the speed.

其中，Δu_dcmax为所述直流微电网的直流母线电压允许最大波动范围值，i_dcmax为所述当前的储能单元所对应的变换器的最大允许输出电流值。Further, the first droop coefficient R( _soci ) satisfies

Wherein, Δu _dcmax is the maximum allowable fluctuation range value of the DC bus voltage of the DC microgrid, and i _dcmax is the maximum allowable output current value of the converter corresponding to the current energy storage unit.

The beneficial effects of adopting the above improvement scheme are: to further ensure the normal operation of the DC microgrid, and to avoid excessively increasing the preset control parameter _n to cause the selection of the first droop coefficient R(soci ) to exceed the allowable drop range of the DC bus voltage, In turn, the entire DC microgrid system loses its stability.

Further, the calculation process of the average state of charge value soc _A includes:

计算得到所述平均荷电状态值soc_A，其中，soc_j为序列号为j的储能单元的荷电状态值，N为所述直流微电网的全部储能单元的总数目。According to the formula

The average state of charge value soc _A is obtained by calculation, wherein soc _j is the state of charge value of the energy storage unit with serial number j, and N is the total number of all energy storage units in the DC microgrid.

The beneficial effect of adopting the above improvement scheme is: combining the droop coefficient with the state of charge value of all energy storage units to reasonably change the size of the droop coefficient, thereby realizing the balance of the state of charge value of the energy storage unit and avoiding its overcharge and overdischarge ,Easy to implement.

Further, before calculating the first droop coefficient corresponding to the current energy storage unit according to the first output current value and the first state of charge value, the method further includes:

Judging whether the first state of charge value soci of the current energy storage unit satisfies 20% _≤soci≤80 % _, and obtaining a first judgment result;

When the first judgment result is no, stop the droop control on the current energy storage unit, and perform charging/discharging processing, until the current energy storage unit meets the preset condition, stop the charging/discharging process Discharge processing is performed, and droop control is performed again on the current energy storage unit.

The beneficial effect of adopting the above improvement scheme is that each energy storage unit is processed according to the state of charge value, and the stability of the operation of the DC microgrid is further improved.

相等，其中，soc_k为序列号为k的储能单元的实时荷电状态值，N为所述直流微电网的全部储能单元的总数目。Further, the preset condition is the real-time state-of-charge value soc of the current energy storage unit and the real-time average state-of-charge value of all energy storage units of the DC microgrid

are equal, where sock is the real-time state-of-charge value of the energy storage unit with serial number _k , and N is the total number of all energy storage units in the DC microgrid.

The beneficial effect of adopting the above improvement scheme is that the droop control is not used for the energy storage unit whose state of charge value is not within the range of 20% to 80%, but the state of charge value of the energy storage unit is adjusted by the charging and discharging process. When the average state of charge value of all the energy storage units, the droop control of the energy storage unit is performed to ensure the system stability of the DC microgrid, and at the same time, it is beneficial to make the state of charge value of each energy storage unit tend to be balanced, so as to achieve a high level of energy storage. Overcharge and over discharge protection.

Further, the current energy storage unit is a battery pack, and the calculation process of the first state of charge value _soci includes:

计算得到所述第一荷电状态值soc_i，其中，C_bat为所述蓄电池组的电池容量，i_L为所述蓄电池组的输出电流值，soc_i0为所述蓄电池组的初始荷电状态值。According to the formula

The first state of charge value soci is obtained by calculation, wherein C _bat is the battery capacity of the battery pack, i _L is the output current value of _{the battery pack, and soc i0 is} the initial state of charge of the battery pack value.

The beneficial effect of adopting the above improvement scheme is that the state of charge value of the battery pack is calculated according to the output current value of the battery pack obtained by sampling, and the calculation is simple and easy to implement.

In a second aspect, the present invention provides a droop control device for a DC microgrid, including a collection module, a calculation module and a control module;

The acquisition module is used to acquire the first output current value of the converter corresponding to the current energy storage unit in real time, and simultaneously acquire the first state of charge value of the current energy storage unit;

The calculation module is configured to calculate the first droop coefficient corresponding to the current energy storage unit according to the first output current value and the first state of charge value;

The control module is configured to perform droop control on the current energy storage unit according to the first droop coefficient.

Further, the computing module includes a first computing module and a second computing module;

计算得到调节因子d_i，其中，soc_i为所述第一荷电状态值，soc_A为所述直流微电网的全部储能单元的平均荷电状态值，n为预设控制参数，i_dci为所述第一输出电流值；The first calculation module is used according to the formula

The adjustment factor d _i is obtained by calculation, where _soci is the first state of charge value, soc _A is the average state of charge value of all energy storage units in the DC microgrid, n is a preset control parameter, and i _dci is the first output current value;

The second calculation module is configured to calculate the first droop coefficient R( _{soci )} according to the formula R(soci )=R ₀ *d _i , where R ₀ is the current energy storage unit. The corresponding preset initial droop coefficient, d _i is the adjustment factor.

In a third aspect, the present invention also 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 made to execute any one of the above The described droop control method for DC microgrid.

Description of drawings

1 is a schematic flowchart of a droop control method for a DC microgrid provided by an embodiment of the present invention;

2 is a schematic circuit diagram of a parallel battery pack in a DC microgrid provided by an embodiment of the present invention;

3 is a schematic structural diagram of a droop control device for a DC microgrid according to an embodiment of the present invention;

FIG. 4 is a schematic structural diagram of a droop control device for a DC microgrid according to another embodiment of the present invention.

Detailed ways

The following examples are further explanations and supplements to the present invention, and do not constitute any limitation to the present invention.

The following describes a droop control method for a DC microgrid according to an embodiment of the present invention with reference to the accompanying drawings.

Referring to FIG. 1, the present invention provides a droop control method for a DC microgrid, including:

S1, obtain the first output current value of the converter corresponding to the current energy storage unit in real time, and simultaneously obtain the first state of charge value of the current energy storage unit;

S2, calculating the 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. Perform droop control on the current energy storage unit according to the first droop coefficient;

S4, adopting the above steps to calculate the corresponding first droop coefficient for each energy storage unit of the DC microgrid respectively, and perform droop control.

A droop control method for a DC microgrid provided by the above embodiment combines the droop coefficient with the state of charge value of the energy storage unit, and changes the size of the droop coefficient in real time according to the current state of charge value of the energy storage unit, and finally The state of charge value of the energy storage unit tends to be balanced, and the problems of overcharge and overdischarge of the energy storage unit and unbalanced state of charge value are avoided.

It can be understood that there may be multiple energy storage units in the energy storage system of the DC microgrid, and the multiple energy storage units are connected in parallel to the DC bus of the DC microgrid respectively through the converter, and the energy storage unit may be a battery. Or energy storage elements such as battery packs.

Specifically, in this embodiment, in order to promote the balance of the state-of-charge values of the energy storage units, the calculated first sag coefficient should satisfy the requirement that the energy storage units with higher state-of-charge values absorb less electricity during the charging process , the energy storage unit with a low state of charge value absorbs more electricity; during the discharge process, the energy storage unit with a high state of charge value releases more electricity, and the energy storage unit with a low state of charge value releases less electricity, so as to achieve storage The equalization of the state of charge value of the energy cells.

Preferably, the calculation process of the first sag coefficient includes:

计算得到调节因子d_i，其中，soc_i为所述第一荷电状态值，soc_A为所述直流微电网的全部储能单元的平均荷电状态值，n为预设控制参数，i_dci为所述第一输出电流值；According to the formula

The adjustment factor d _i is obtained by calculation, where _soci is the first state of charge value, soc _A is the average state of charge value of all energy storage units in the DC microgrid, n is a preset control parameter, and i _dci is the first output current value;

According to the formula R(soci )=R ₀ *d _i , the first droop coefficient R( _{soci )} is obtained by calculation, wherein R ₀ is the preset initial droop coefficient corresponding to the current energy storage unit, d _i is the adjustment factor.

In this embodiment, by adjusting the preset control parameter n in the adjustment factor d _i , the equalization speed of the state of charge value can be controlled, so that the state of charge value can be increased by increasing the preset control parameter n Equalize speed.

Further, the calculation process of the average state of charge value soc _A includes:

计算得到所述平均荷电状态值soc_A，其中，soc_j为序列号为j的储能单元的荷电状态值，N为所述直流微电网的全部储能单元的总数目。According to the formula

The average state of charge value soc _A is obtained by calculation, wherein soc _j is the state of charge value of the energy storage unit with serial number j, and N is the total number of all energy storage units in the DC microgrid.

It can be understood that the calculation of the droop coefficient should be divided into two cases of charging and discharging states. If i _dci >0, the energy storage unit is in the discharge state. If the state of charge value of the energy storage unit is greater than the average value, for example, _soci >soc _A , it can be known that the calculated first droop coefficient R( _soci ) <R ₀ , that is, compared with the preset initial droop coefficient R ₀ , the energy storage unit will provide a larger load current than when the adjustment factor is not added. It is thus known that if the state of charge value is less than the average value, the energy storage unit will The energy unit will provide a smaller load current than if no adjustment factor is added; when i _dci < 0, the energy storage unit is in the state of charge, and if the state of charge value of the energy storage unit is greater than the average value, that is, _soci >soc _A , Then there is R( _soci )>R ₀ , then the energy storage unit will absorb a smaller load current than when no adjustment factor is added. From this, it is known that if the state of charge value is less than the average value, the energy storage unit will A larger load current is absorbed when adjusting the factor.

Therefore, the droop coefficient calculated by the adjustment factor can realize the balance of the state of charge of the energy storage unit and the overcharge and overdischarge protection.

其中，Δu_dcmax为所述直流微电网的直流母线电压允许最大波动范围值，i_dcmax为所述当前的储能单元所对应的变换器的最大允许输出电流值。Optionally, in one embodiment, the first sag coefficient R( _soci ) satisfies

Wherein, Δu _dcmax is the maximum allowable fluctuation range value of the DC bus voltage of the DC microgrid, and i _dcmax is the maximum allowable output current value of the converter corresponding to the current energy storage unit.

充电状态下为：

其中，R₀为所述预设初始下垂系数。It should be noted that in the droop control, the calculated droop coefficient R( _soci ) should be within the allowable range of the bus voltage drop. If the value is too large, there may be a large deviation between the bus voltage and its actual reference value. As a result, the entire DC microgrid system is unstable, so the corresponding droop coefficient selection rule in the discharge state is:

In charging state:

Wherein, R ₀ is the preset initial droop coefficient.

Further, in an embodiment, before calculating the first droop coefficient corresponding to the current energy storage unit according to the first output current value and the first state of charge value, the method further includes:

Judging whether the first state of charge value soci of the current energy storage unit satisfies 20% _≤soci≤80 % _, and obtaining a first judgment result;

When the first judgment result is no, stop the droop control on the current energy storage unit, and perform charging/discharging processing, until the current energy storage unit meets the preset condition, stop the charging/discharging process Discharge processing is performed, and droop control is performed again on the current energy storage unit.

相等，其中，soc_k为序列号为k的储能单元的实时荷电状态值，N为所述直流微电网的全部储能单元的总数目。Preferably, the preset condition is the real-time state-of-charge value soc of the current energy storage unit and the real-time average state-of-charge value of all energy storage units of the DC microgrid

are equal, where sock is the real-time state-of-charge value of the energy storage unit with serial number _k , and N is the total number of all energy storage units in the DC microgrid.

It should be noted that the optimal applicable condition of the above 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%, it should be Forbid its charging, only allow it to work in the discharge state, that is, discharge the energy storage unit; when there is an energy storage unit with a state of charge value less than 20%, its discharge should be prohibited, and only it is allowed to work in the charged state , that is, the energy storage unit is charged, and the above-mentioned droop control method is not used for the energy storage unit that is charged/discharged, until the state of charge value of the energy storage unit is adjusted to the current value of all energy storage units. When the state of charge is averaged, the above-mentioned droop control method is applied to the energy storage unit, and the charging and discharging work is performed synchronously with other energy storage units.

Further, in one embodiment, the current energy storage unit is a battery pack, and the calculation process of the first state of charge value _soci includes:

计算得到所述第一荷电状态值soc_i，其中，C_bat为所述蓄电池组的电池容量，i_L为所述蓄电池组的输出电流值，soc_i0为所述蓄电池组的初始荷电状态值。According to the formula

The first state of charge value soci is obtained by calculation, wherein C _bat is the battery capacity of the battery pack, i _L is the output current value of _{the battery pack, and soc i0 is} the initial state of charge of the battery pack value.

Specifically, in this embodiment, the battery packs can be connected in parallel on the DC bus through 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 connected in parallel to the DC bus through the converter respectively to supply power to the load; u _bat1 and u _bat2 are the output voltage of the battery pack 1 and the battery pack 1 respectively. The output voltage of group 2, i _L1 and i _L2 are the output currents of battery group 1 and battery group 2 respectively, S ₁ , S ₂ , S ₃ , and S ₄ are IGBTs (insulated gate bipolar transistors), R is the load resistance, Among them, the inductor L ₁ , the insulated gate bipolar transistors S ₁ and S ₂ and the capacitor C ₁ form the converter 1 corresponding to the battery pack 1 , the inductor L ₂ , the insulated gate bipolar transistors S ₃ and S ₄ and The capacitor C ₂ forms the converter 2 corresponding to the battery pack 2 , u _dc1 and u _dc2 are the output voltages of the converters 1 and 2 respectively, and i _dc1 and _idc2 are the output currents of the converters 1 and 2 respectively ;

其中，C_bat1为所述蓄电池组1的电池容量，soc₁₀为所述蓄电池组1的初始荷电状态值，同时对蓄电池组2进行相似计算步骤得到荷电状态值soc₂；在计算得到soc₁、soc₂后检测soc₁、soc₂是否处于20％到80％范围之内，当并联蓄电池组中存在荷电状态值大于80％的蓄电池组时，应该禁止其充电，只允许其工作在放电状态；当蓄电池组中存在荷电状态值小于20％时，应该禁止其放电，只允许其工作在充电状态下，且在上述两种情况下的蓄电池组其放电和充电模式不采用上述下垂控制方法，可采用传统充放电模式。当把蓄电池组荷电状态值调整至蓄电池的平均荷电状态值时，再将其与其他蓄电池组一起充放电；Further, in this embodiment, for the battery pack 1, first detect the output current value i _dc1 of the converter 1 and calculate the current state of charge value soc ₁ of the battery pack 1, the calculation formula of soc ₁ is:

Wherein, C _bat1 is the battery capacity of the battery pack 1, soc ₁₀ is the initial state-of-charge value of the battery pack 1, and at the same time, similar calculation steps are performed on the battery pack 2 to obtain the state-of-charge value soc ₂ ; _1. After soc ₂ , check whether soc ₁ and soc ₂ are within the range of 20% to 80%. When there is a battery pack with a state of charge value greater than 80% in the parallel battery pack, its charging should be prohibited, and it should only be allowed to work in Discharge state; when the state of charge value in the battery pack is less than 20%, its discharge should be prohibited, only it is allowed to work in the charged state, and the discharge and charge modes of the battery pack in the above two cases do not use the above droop The control method can adopt the traditional charging and discharging mode. When the state-of-charge value of the battery pack is adjusted to the average state-of-charge value of the battery, charge and discharge it together with other battery packs;

此时N＝2；If soc ₁ and soc ₂ are within the range of 20% to 80%, first calculate soc _A , and its calculation formula is

At this time N=2;

当i_dc1＜0，蓄电池组1处于充电状态，则调节因子d₁为：

对蓄电池组2进行相似计算步骤得到调节因子d₂，其中，调节因子中可以通过调节预设控制参数n来加速荷电状态值的均衡，但其必须在母线电压允许跌落的范围内；At the same time, the positive and negative of i _dc1 and i _dc2 of battery packs 1 and 2 are judged respectively; for battery pack 1, when i _dc1 > 0, and battery pack 1 is in a discharge state, the adjustment factor d ₁ is:

When i _dc1 < 0, and the battery pack 1 is in the charging state, the adjustment factor d ₁ is:

Similar calculation steps are performed on the battery pack 2 to obtain the adjustment factor d ₂ , wherein, in the adjustment factor, the balance of the state of charge value can be accelerated by adjusting the preset control parameter n, but it must be within the range that the bus voltage is allowed to drop;

其中，u_dcref为直流母线参考电压。Finally, the adjusted droop coefficients R(soc ₁ ) and R(soc ₂ ) of battery packs 1 and 2 are obtained by formulas R(soc ₁ )=R ₀₁ *d ₁ , R(soc ₂ )=R ₀₂ *d ₂ , In this way, the state of charge of the battery packs 1 and 2 tends to be balanced, and overcharge and overdischarge are avoided, wherein R ₀₁ and R ₀₂ are the preset initial droop coefficients corresponding to the battery pack 1 and the battery pack 2 respectively; further , adopt the above-mentioned droop control method for battery pack 1 and battery pack 2, specifically adjusting the relevant parameters of the corresponding converters according to the adjusted droop coefficient so that the outputs of the two battery packs satisfy the droop formula: u _dc1 =u _dcref -i _dc1 R(soc ₁ ), u _dc2 = u _dcref -i _dc2 R(soc ₂ ) and

Among them, u _dcref is the DC bus reference voltage.

The droop control method for the DC microgrid provided in the above embodiment is simple, easy to understand and implement, and has good application prospects. The droop control method combines the droop coefficient with the state of charge value of the battery pack, The current state of charge value changes the size of the droop coefficient in real time, and can adjust the equalization speed of the state of charge value, so as to realize the equalization of the state of charge value of the battery pack and avoid its overcharge and overdischarge.

In the above embodiments, although the steps are numbered, such as S1, S2, etc., they are only specific embodiments given in this application, and those skilled in the art can adjust the execution order of S1, S2, etc. according to the actual situation, This is also within the protection scope of the present invention, and it can be understood that in some embodiments, some or all of the above-mentioned embodiments may be included.

As shown in FIG. 3 , a droop control device 10 for a DC microgrid provided by an embodiment of the present invention includes a collection module 20 , a calculation module 30 and a control module 40 ;

The acquisition module 20 is configured to acquire the first output current value of the converter corresponding to the current energy storage unit in real time, and simultaneously acquire the first state of charge value of the current energy storage unit;

The calculation module 30 is configured to calculate and obtain the first droop coefficient corresponding to the current energy storage unit according to the first output current value and the first state of charge value;

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 computing module 30 includes a first computing module and a second computing module;

计算得到调节因子d_i，其中，soc_i为所述第一荷电状态值，soc_A为所述直流微电网的全部储能单元的平均荷电状态值，n为预设控制参数，i_dci为所述第一输出电流值；The first calculation module is used according to the formula

The adjustment factor d _i is obtained by calculation, where _soci is the first state of charge value, soc _A is the average state of charge value of all energy storage units in the DC microgrid, n is a preset control parameter, and i _dci is the first output current value;

The second calculation module is configured to calculate the first droop coefficient R( _{soci )} according to the formula R(soci )=R ₀ *d _i , where R ₀ is the current energy storage unit. The corresponding preset initial droop coefficient, d _i is the adjustment factor.

其中，Δu_dcmax为所述直流微电网的直流母线电压允许最大波动范围值，i_dcmax为所述当前的储能单元所对应的变换器的最大允许输出电流值。Preferably, the first sag coefficient R( _soci ) satisfies

Wherein, Δu _dcmax is the maximum allowable fluctuation range value of the DC bus voltage of the DC microgrid, and i _dcmax is the maximum allowable output current value of the converter corresponding to the current energy storage unit.

计算得到所述平均荷电状态值soc_A，其中，soc_j为序列号为j的储能单元的荷电状态值，N为所述直流微电网的全部储能单元的总数目。Optionally, in one embodiment, the calculation module 30 further includes a third calculation module; the third calculation module is used for formulating

The average state of charge value soc _A is obtained by calculation, wherein soc _j is the state of charge value of the energy storage unit with serial number j, and N is the total number of all energy storage units in the DC microgrid.

Optionally, in an embodiment, referring to FIG. 4 , it further includes a judgment module 50, and the judgment module 50 is used to judge whether the first state of charge value _soci of the current energy storage unit satisfies 20. % _≤soci ≤80%, the first judgment result is obtained; when the first judgment result is no, the droop control is stopped for the current energy storage unit, and charge/discharge processing is performed until the current energy storage unit is When the energy storage unit satisfies the preset condition, the charging/discharging process is stopped, and the droop control is performed again on the current energy storage unit.

相等，其中，soc_k为序列号为k的储能单元的实时荷电状态值，N为所述直流微电网的全部储能单元的总数目。Preferably, the preset condition is the real-time state-of-charge value soc of the current energy storage unit and the real-time average state-of-charge value of all energy storage units of the DC microgrid

are equal, where sock is the real-time state-of-charge value of the energy storage unit with serial number _k , and N is the total number of all energy storage units in the DC microgrid.

计算得到所述第一荷电状态值soc_i，其中，C_bat为所述蓄电池组的电池容量，i_L为所述蓄电池组的输出电流值，soc_i0为所述蓄电池组的初始荷电状态值。Optionally, in one embodiment, the current energy storage unit is a battery pack, and the collection module 20 is specifically configured to

The first state of charge value soci is obtained by calculation, wherein C _bat is the battery capacity of the battery pack, i _L is the output current value of _{the battery pack, and soc i0 is} the initial state of charge of the battery pack value.

An embodiment of the present invention further provides a computer-readable storage medium, where an instruction is stored in the computer-readable storage medium, and when the instruction is executed on a terminal device, the terminal device is made to execute the above-mentioned method for direct current The parameters and steps in the embodiments of the microgrid droop control method will not be described in detail here.

As will be appreciated by one skilled in the art, the present invention may be implemented as an apparatus, method or computer program product. Therefore, the present disclosure can be embodied in the following forms, that is: it can be complete hardware, it can also be complete software (including firmware, resident software, microcode, etc.), or it can be a combination of hardware and software. Referred to as a "circuit," "module," or "device." Furthermore, in some embodiments, the present invention may also be implemented in the form of a computer program product on one or more computer-readable media having computer-readable program code embodied thereon.

In the description of this specification, description with reference to the terms "one embodiment," "some embodiments," "example," "specific example," or "some examples", etc., mean specific features described in connection with the embodiment or example , structure, material or feature is included in at least one embodiment or example of the present invention. In this specification, schematic representations of the above terms are not necessarily directed 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, those skilled in the art may combine and combine the different embodiments or examples described in this specification, as well as the features of the different embodiments or examples, without conflicting each other.

Although the embodiments of the present invention have been shown and described above, it should be understood that the above-mentioned embodiments are exemplary and should not be construed as limiting the present invention. Embodiments are subject to variations, modifications, substitutions and variations.

Claims (8)

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;

respectively calculating a corresponding first droop coefficient for each energy storage unit of the direct current microgrid by adopting the steps, and performing droop control;

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 unit _i Whether the soc is more than or equal to 20 percent _i Less than or equal to 80 percent to obtain a first judgment result;

when the first judgment result is negative, stopping droop control on the current energy storage unit, and performing charging/discharging treatment, and when 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 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

Equal to, wherein soc _k The real-time state of charge value of the energy storage units with the serial number k is obtained, and N is the total number of all the energy storage units of the direct current micro-grid.

2. The droop control method for the direct-current microgrid according to claim 1, characterized in that the calculation process of the first droop coefficient comprises:

according to the formula

Calculating to obtain an adjusting factor d _i Wherein, soc _i Is said first state of charge value, soc _A Is the average charge state value of all energy storage units of the direct current micro-grid, n is a preset control parameter, i _dci Is the first output current value;

according to the formula R (soc) _i )＝R ₀ *d _i And calculating to obtain the first sag coefficient R (soc) _i ) Wherein R is ₀ A preset initial droop coefficient, d, corresponding to the current energy storage unit _i Is the regulatory factor.

3. The droop control method for the direct current microgrid of claim 2, characterized in that the first droop coefficient R (soc) _i ) Satisfy the requirements of

Wherein, Δ u _dcmax Allowing the maximum fluctuation range value i for the DC bus voltage of the DC micro-grid _dcmax And 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 soc _A The calculation process of (2) comprises:

according to the formula

Calculating to obtain the average state of charge value soc _A Wherein, soc _j The 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 the current energy storage unit is a storage battery, and the first state of charge value soc _i The calculation process of (2) includes:

according to the formula

Calculating to obtain the first state of charge value soc _i Wherein, C _bat Is the cell capacity of the battery pack, i _L Is the output current value of the battery pack, soc _i0 And the initial state of charge value of the storage battery pack is obtained.

6. A droop control device for a direct current micro-grid is characterized by comprising an acquisition module, a calculation module, a judgment 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;

the control module is used for carrying out droop control on the current energy storage unit according to the first droop coefficient;

the judging module is used for judging the current first state of charge (soc) value of the energy storage unit _i Whether the soc is more than or equal to 20 percent _i Less than or equal to 80 percent to obtain a first judgment result; when the first judgment result is negative, stopping the current energy storage unitPerforming droop control, performing charge/discharge treatment until the current energy storage unit meets a preset condition, stopping the charge/discharge treatment, and performing droop control on the current energy storage unit again; the preset conditions are the real-time charge state value soc of the current energy storage unit and the real-time average charge state value of all the energy storage units of the direct-current micro-grid

Equal to, wherein soc _k The 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 device for the direct current microgrid according to claim 6, characterized in that 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

Calculating to obtain an adjusting factor d _i Wherein, soc _i Is the first state of charge value, soc _A Is the average charge state value of all energy storage units of the direct current micro-grid, n is a preset control parameter, i _dci Is the first output current value;

the second calculation module is used for calculating the formula R (soc) _i )＝R ₀ *d _i And calculating to obtain the first sag coefficient R (soc) _i ) Wherein R is ₀ A preset initial droop coefficient, d, corresponding to the current energy storage unit _i Is the regulatory factor.

8. 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 1-5.

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