Power balance and dynamic compensation system based on sodium electricity energy storage

Abstract

The invention relates to the technical field of power grid regulation and control, and discloses a power balance and dynamic compensation system based on sodium electricity energy storage, which is based on an energy storage unit formed by a sodium battery pack and comprises a region division module, a power balance module, a power balance module and a dynamic compensation module, the discharge calculation module calculates a first target droop coefficient according to the real-time SOC value of the energy storage unit and the discharge equalization factor, and the charge calculation module calculates a second target droop coefficient according to the real-time SOC value of the energy storage unit and the charge equalization factor. The power compensation module performs charging and discharging scene power compensation according to the first target droop coefficient / the second target droop coefficient, and the SOC equalization module calculates the average SOC of the energy storage unit in each cycle to adjust the target droop coefficient. According to the method, the dynamic adjustment mechanism is embedded into the droop coefficient, the droop coefficient is dynamically adjusted according to the SOC in the charging and discharging process, accurate power distribution and rapid SOC equalization in the charging and discharging process are achieved, the system stability is improved, and the service life of the battery is prolonged.

Description

Technical Field

[0001] The present invention relates to the technical field of power grid regulation, and in particular to a power balancing and dynamic compensation system based on sodium battery energy storage. Background Art

[0002] Usually, an energy storage system is composed of multiple energy storage units running in parallel. Each unit is connected to the DC bus through a DC / DC converter. The key and technical difficulty of its control is how to distribute power among multiple energy storage units and achieve balanced control of the state of charge (SOC). Droop control has the advantages of no need for communication, multiple units jointly controlling DC voltage and power, and plug-and-play, and has been widely used in DC power supply systems. The traditional droop control strategy only distributes power based on voltage or frequency deviation, and cannot effectively solve the problem of unbalanced state of charge (SOC) between energy storage units, resulting in overcharge / over-discharge of some batteries and shortened life. Moreover, the coefficient of traditional droop control is a fixed coefficient and cannot be dynamically adjusted according to SOC, let alone achieve balanced control of SOC. Under certain working conditions, the power allocated to the energy storage unit may also be unreasonable, and may even cause the battery pack to be over-discharged or over-charged, affecting the life of the battery pack. Summary of the Invention

[0003] The present invention provides a power balancing and dynamic compensation system based on sodium battery energy storage. By embedding a dynamic regulation mechanism in the droop coefficient, the droop coefficient is dynamically adjusted according to the SOC during the charging and discharging process, thereby achieving precise power distribution and rapid SOC balancing during the charging and discharging process, thereby improving system stability and battery life.

[0004] The present invention provides a power balancing and dynamic compensation system based on sodium battery energy storage, which is an energy storage unit composed of a sodium battery pack. The system includes a region division module, a discharge calculation module, a charge calculation module, a power compensation module, a SOC balancing module, and a real-time monitoring feedback module connected in sequence.

[0005] The area division module is used to divide the charge and discharge of the sodium battery pack into five working areas according to the SOC value of the sodium battery pack; wherein the working areas include a prohibited discharge area, a restricted discharge area, a free charge and discharge area, a restricted charge area, and a prohibited charge area;

[0006] The discharge calculation module is used to calculate a first target droop coefficient according to the real-time SOC value of the energy storage unit and a discharge balancing factor, so as to perform adaptive droop control during discharge according to the first target droop coefficient;

[0007] The charging calculation module is used to calculate a second target droop coefficient according to the real-time SOC value of the energy storage unit and the charging balancing factor, so as to perform adaptive droop control during charging according to the second target droop coefficient;

[0008] The power compensation module is configured to perform power compensation in a discharge scenario according to the first target droop coefficient, or perform power compensation in a charging scenario according to the second target droop coefficient;

[0009] The SOC balancing module is used to calculate the average SOC of the energy storage unit in each cycle, and adjust the first target droop coefficient or the second target droop coefficient according to the average SOC to achieve SOC balance feedback regulation;

[0010] The real-time monitoring feedback module is used to trigger an emergency shutdown and freeze the power distribution of the sodium battery group when the detected terminal voltage of the sodium battery group exceeds a safe range or the charge and discharge current exceeds a rated value.

[0011] Furthermore, in the area division module,

[0012] Assume that the SOC of the sodium battery pack at the initial time t0 is S OC0 , when the sodium battery pack is charged and discharged, the SOC at any time t is:

[0013]

[0014] Among them, S OC is the SOC value of the sodium battery pack at time t, Q is the maximum capacity of the sodium battery pack that can store charge, P bess The power used to charge or discharge the sodium battery pack; when charging, P bess <0, when discharging, P bess >0;

[0015] The charge and discharge of sodium battery packs are divided into five working areas according to the SOC value:

[0016] Discharge prohibited area: SOC is between 0% and S OC1 , the battery is not allowed to discharge at this time;

[0017] Restricted discharge area: SOC in S OC1 and S OC2 In this area, as the SOC value decreases, the discharge of the battery is gradually limited;

[0018] Free charge and discharge area: SOC in S OC2 and S OC3 There is no restriction on battery charge and discharge at this time;

[0019] Restricted charging area: SOC in S OC3 and SOC4 In this area, as the SOC value increases, the battery charging is gradually restricted;

[0020] Prohibited charging area: SOC between S OC4 To 100%, the battery is not allowed to charge;

[0021] Among them, S OC1 、S OC2 、S OC3 、S OC4 The value of S is determined by the parameters of the battery pack itself. OC1 The value range of S is 5% to 10%. OC2 The value range of S is 40% to 50%. OC3 The value range of S is 50% to 60%. OC4 The value range is 90% to 95%.

[0022] Furthermore, in the discharge calculation module,

[0023] When the i-th energy storage unit is discharged, the expression for determining the droop coefficient is:

[0024]

[0025] Among them, S OCi is the SOC value of the i-th energy storage unit, k0 is the initial value of the droop coefficient, k max is the maximum value of the droop coefficient; and according to S OCi The calculation formula for determining the discharge balance factor is:

[0026]

[0027]

[0028] Among them, δ i is the discharge balance factor, S OCavr is the average SOC value of m energy storage units, ΔS OCi is the S of the i-th energy storage unit OCi With the average value S OCavr The difference between the two, a is the difference adjustment coefficient of the equalization factor, and b is the power exponential adjustment coefficient of the equalization factor;

[0029] The energy storage unit is based on the droop coefficient k' i and discharge balance factor δ i Multiply to get the first target droop coefficient k i .

[0030] Furthermore, in the charging calculation module,

[0031] When the i-th energy storage unit is charged, the expression for determining the droop coefficient is:

[0032]

[0033] Among them, S OCi is the SOC value of the i-th energy storage unit; and according to S OCi The calculation formula for determining the charge equalization factor is:

[0034]

[0035] Among them, γ i is the charge balancing factor; the energy storage unit is based on the droop coefficient k″ i and the charge balancing factor γ i Multiply to get the second target droop coefficient k i .

[0036] Furthermore, the maximum value of the droop coefficient k max Defined as:

[0037]

[0038] Among them, P s is the rated capacity of the energy storage unit, ΔV dcmax is the maximum allowable DC voltage deviation;

[0039] According to the maximum value of the droop coefficient k max The range of the initial value k0 of the droop coefficient is determined to be: 0.1k max ≤k0≤0.3k max ;

[0040] The first target droop coefficient k i and the second target droop coefficient k i Are less than or equal to k max .

[0041] Furthermore, in the power compensation module,

[0042] According to the droop control principle, the target power calculation formula of the sodium battery pack is:

[0043]

[0044] Among them, P i is the output power of the i-th energy storage unit, discharge is positive and charge is negative; U 0i is the rated voltage of the i-th energy storage unit; U bus is the common bus voltage; k i During discharge, it is the first target droop coefficient, and during charge, it is the second target droop coefficient;

[0045] The controller sets the output power P of the i-th energy storage unit to i Convert to current command And sent to the converter PCS of the i-th energy storage unit to control its charging and discharging current.

[0046] Furthermore, in the SOC balancing module,

[0047] The average SOC of the energy storage unit is calculated every cycle. The calculation formula is:

[0048]

[0049] Among them, S OCavg is the average SOC of the energy storage unit, C i is the energy storage unit capacity, and evaluates the deviation of the energy storage unit SOC from the average value:

[0050] If the energy storage unit S OCi >S OCavg +ΔSOC, further reducing the first target droop coefficient k during the next discharge cycle i , or further increase the second target droop coefficient k during the next charging cycle i , to enhance its more discharge / less charge;

[0051] If the energy storage unit S OCi OCavg -ΔSOC, further reduce the second target droop coefficient k during the next charging cycle i , or further increase the first target droop coefficient k in the next cycle discharge i , to enhance its more charging / less discharging.

[0052] Furthermore, in the real-time monitoring feedback module,

[0053] Real-time monitoring of the sodium battery terminal voltage U in the energy storage unit i , and when the sodium battery terminal voltage U i When the safety range is exceeded or the charge / discharge current exceeds the rated value, an emergency shutdown is triggered, a fault is reported, and the power distribution of the sodium battery pack of the energy storage unit is frozen; wherein, the safety range is: the sodium battery pack terminal voltage U i max , or the terminal voltage U of the sodium battery pack during charging i >U min .

[0054] The beneficial effects of the present invention are:

[0055] ​​The area division module of the present invention divides the charging and discharging of the sodium battery pack into five working areas according to the SOC value of the sodium battery pack; the discharge calculation module calculates a first target droop coefficient according to the real-time SOC value of the energy storage unit and the discharge balancing factor; the charging calculation module calculates a second target droop coefficient according to the real-time SOC value of the energy storage unit and the charge balancing factor; the power compensation module performs power compensation for charging and discharging scenarios according to the first target droop coefficient / the second target droop coefficient; the SOC balancing module calculates the average SOC of the energy storage unit per cycle to adjust the target droop coefficient; the present invention introduces the SOC of the battery pack into the droop coefficient; when the energy storage unit is discharging, the battery pack with a larger SOC bears more discharge power, and when charging, the battery pack with a smaller SOC bears more charging power; and the droop coefficient is dynamically adjusted according to the SOC during the charging and discharging process, thereby achieving reasonable power distribution and balanced control of the SOC of each energy storage unit, thereby improving system stability and battery life. BRIEF DESCRIPTION OF THE DRAWINGS

[0056] Figure 1 It is a structural schematic diagram of the power balance and dynamic compensation system based on sodium battery energy storage of the present invention.

[0057] The purpose, features and advantages of the present invention will be further described with reference to the accompanying drawings and in conjunction with the embodiments. DETAILED DESCRIPTION

[0058] It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0059] like Figure 1 As shown, the present invention provides a power balancing and dynamic compensation system based on sodium battery energy storage, which is an energy storage unit composed of a sodium battery pack. The system includes a region division module, a discharge calculation module, a charge calculation module, a power compensation module, an SOC balancing module, and a real-time monitoring feedback module connected in sequence.

[0060] (1) Area division module

[0061] The area division module is used to divide the charging and discharging of the sodium battery pack into five working areas according to the SOC value of the sodium battery pack; wherein the working areas include a prohibited discharge area, a restricted discharge area, a free charge and discharge area, a restricted charge area, and a prohibited charge area.

[0062] Assume that the SOC of the sodium battery pack at the initial time t0 is S OC0 , when the sodium battery pack is charged and discharged, the SOC at any time t is:

[0063]

[0064] Among them, S OCis the SOC value of the sodium battery pack at time t, Q is the maximum capacity of the sodium battery pack that can store charge, P bess The power used to charge or discharge the sodium battery pack; when charging, P bess <0, when discharging, P bess >0;

[0065] The charge and discharge of sodium battery packs are divided into five working areas according to the SOC value:

[0066] 1) Discharge prohibited area: SOC is between 0% and S OC1 At this time, the battery is not allowed to discharge to avoid excessive discharge of the battery and affecting its life.

[0067] 2) Restricted discharge area: SOC is S OC1 and S OC2 In this area, as the SOC value decreases, the battery discharge is gradually limited, the output of the energy storage unit is reduced, and the SOC is prevented from reaching S OC1 When the discharge is stopped directly, it will bring greater power disturbance to the system.

[0068] 3) Free charge and discharge area: SOC is S OC2 and S OC3 During this time, there is no restriction on battery charging and discharging, and the energy storage unit charges and discharges according to the needs of the system.

[0069] 4) Restricted charging area: SOC in S OC3 and S OC4 In this area, as the SOC value increases, the battery charging is gradually restricted, the charging power of the energy storage unit is reduced, and the SOC is prevented from reaching S OC4 When the battery is fully charged, charging is stopped directly, which brings greater power disturbance to the system.

[0070] 5) Prohibited charging area: SOC between S OC4 To avoid overcharging the battery and shortening its life, the battery is not allowed to charge to 100%.

[0071] Among them, S OC1 、S OC2 、S OC3 、S OC4 The value of S is determined by the parameters of the battery pack itself. OC1 The value range of S is 5% to 10%. OC2 The value range of S is 40% to 50%. OC3 The value range of S is 50% to 60%. OC4 The value range is 90% to 95%.

[0072] (2) Discharge calculation module

[0073] When allocating power between energy storage units, the droop coefficient is typically set based solely on the capacity of the energy storage unit, resulting in a fixed coefficient. This power allocation process can cause the sodium battery pack to overcharge or discharge, while other energy storage units still have charge and discharge capacity, impacting battery life. Clearly, using a fixed coefficient for droop control cannot adapt to power allocation between energy storage units at varying SOCs. Therefore, when allocating power between energy storage units, the SOC of their own sodium battery packs must also be considered.

[0074] To solve this problem, the SOC of the battery pack is introduced into the droop coefficient. When the energy storage unit is discharging, the battery pack with a larger SOC bears more discharge power, and when charging, the battery pack with a smaller SOC bears more charging power. In addition, the droop coefficient is dynamically adjusted according to the SOC during the charging and discharging process to achieve reasonable power distribution and balanced control of the SOC of each energy storage unit.

[0075] The discharge calculation module is used to calculate a first target droop coefficient according to the real-time SOC value of the energy storage unit and a discharge balancing factor, so as to perform adaptive droop control during discharge according to the first target droop coefficient.

[0076] When the i-th energy storage unit discharges and the battery pack enters the restricted discharge region, the droop coefficient of the energy storage unit should be increased, the power allocated to it should be reduced, and the discharge speed of the battery pack should be slowed down. Therefore, during discharge, the expression of the droop coefficient of the adaptive droop control considering SOC is:

[0077]

[0078] Among them, k' i is the droop coefficient determined by the SOC of the energy storage unit during discharge; S OCi is the SOC value of the i-th energy storage unit, k0 is the initial value of the droop coefficient, k max is the maximum value of the droop coefficient; when S OCi Greater than S OC2 When the droop coefficient k' i Equal to the initial value k0, indicating that the discharge power of the battery pack is not limited, and the energy storage unit distributes power according to the initial droop coefficient k0; when the battery pack discharges into the restricted discharge area, that is, S OCi In S OC1 and S OC2 Between, droop coefficient k' i With S OCi The power allocated to the corresponding energy storage unit gradually decreases until the battery pack enters the prohibited discharge area (S OC1 ), the droop coefficient is equal to the maximum value k max , at which point the battery pack stops discharging.

[0079] The above formula only considers the SOC of the energy storage unit itself, and does not consider the SOC of other energy storage units. In some operating conditions, the SOC balance of each energy storage unit cannot be achieved. Therefore, the SOC of each energy storage unit needs to be considered during the discharge process to achieve balanced control of the SOC of each unit. Therefore, the discharge balance factor is introduced. OCi The calculation formula for determining the discharge balance factor is:

[0080]

[0081] Among them, δ i is the discharge balance factor, S OCavr is the average SOC value of m energy storage units, ΔS OCi is the S of the i-th energy storage unit OCi With the average value S OCavr The difference between the two, a is the difference adjustment coefficient of the equalization factor (set to 2), and b is the power exponential adjustment coefficient of the equalization factor (set to 5).

[0082] The energy storage unit first determines the droop coefficient k based on its own SOC ' i , and then multiply it by the discharge balance factor to get the final droop coefficient k i :

[0083] k i =δ i k′ i

[0084] When ΔS OCi When it is less than 0, it means that the S of the i-th energy storage unit OCi Less than the average S OCavr , at this time the balance factor is greater than 1, k i >k' i , the discharge balance factor increases the droop coefficient of the unit, and its allocated power decreases, that is, when the S OCi Less than the average value S of each energy storage unit OCavr When the SOC of the energy storage unit is OCi Greater than the average value S of each unit OCavr When the equalization factor is less than 1, k i <k' i The discharge balancing factor reduces the droop coefficient of the unit, increases the allocated discharge power, and accelerates the rate of SOC decline. Therefore, under the action of the discharge balancing factor, the SOC of each unit will tend to be balanced.

[0085] (3) Charging calculation module

[0086] The charging calculation module is used to calculate a second target droop coefficient according to the real-time SOC value of the energy storage unit and a charging balancing factor, so as to perform adaptive droop control during charging according to the second target droop coefficient.

[0087] Similar to the discharge characteristics, when the i-th energy storage unit is charged, the expression for determining the droop coefficient is:

[0088]

[0089] Where k i is the droop coefficient determined by the SOC of the energy storage unit during charging, S OCi is the SOC value of the i-th energy storage unit; when S OCi Less than S OC3 When the droop coefficient k i Equal to the initial value k0, indicating that the charging power of the sodium battery pack is not restricted, and the energy storage unit distributes power according to the initial droop coefficient k0; when the sodium battery pack enters the restricted charging area, that is, S OCi In S OC3 and S OC4 Between, droop coefficient k i With S OCi The charging power allocated by the unit gradually decreases, and the charging speed of the sodium battery pack gradually slows down until the sodium battery pack enters the prohibited charging area (S OC4 ), the droop coefficient is equal to the maximum value k max , at which point the sodium battery pack stops charging.

[0090] Similar to discharging, when charging the energy storage unit, it is also necessary to consider the SOC of each unit and introduce a charging balancing factor. OCi The calculation formula for determining the charge equalization factor is:

[0091]

[0092] Among them, γ i is the charge balancing factor; the energy storage unit is based on the droop coefficient k″ i and the charge balancing factor γ i Multiply to get the second target droop coefficient k i .

[0093] The droop coefficient k" determined by the energy storage unit's own SOC during charging i Multiplying it with the charge balancing factor gives the droop coefficient k during charging. i for:

[0094] k i =γ i ·k″ i

[0095] When the S of the energy storage unit OCi When it is smaller (less than the average value S OCavr ), γ i <1, k i <k″ i , the charging balancing factor reduces the droop coefficient of the unit, the allocated charging power increases, and the SOC rises faster; when the S OCi When it is larger (greater than the average value S OCavr ), γ i >1,k i >k″ i The charging balancing factor increases the droop coefficient of the unit, reduces the allocated charging power, and slows down the SOC rise. Therefore, under the action of the charging balancing factor, the SOC of each unit will tend to be balanced.

[0096] In the discharge calculation module and the charge calculation module, the parameters are set as follows:

[0097] The droop coefficient is related to power distribution. The smaller the droop coefficient, the more initial power and disturbance power will be distributed to the energy storage unit. The droop coefficient also affects the DC voltage. To ensure that the DC voltage is within the allowable operating range, combined with the capacity of the converter, the maximum value of the droop coefficient k max Defined as:

[0098]

[0099] Among them, P s is the rated capacity of the energy storage unit, ΔV dcmax is the maximum allowable DC voltage deviation. The above formula shows that within the allowable range of DC voltage, the power of the energy storage unit can be adjusted. Considering the insulation and pulse width modulation ratio, the maximum allowable DC voltage deviation of the DC system is usually 0.1~0.2pu, so k max The value is 0.1~0.2.

[0100] The droop coefficient cannot be too small. If it is too small, the energy storage unit will be close to the constant voltage control, which will lead to inaccurate power control of the energy storage unit. Considering the flexibility of control and the rationality of power distribution, according to the maximum value of the droop coefficient k max The range of the initial value k0 of the droop coefficient is determined to be: 0.1k max ≤k0≤0.3k max .

[0101] In addition, considering the stability of the system and the rationality of power distribution, the calculated k after considering the charging or discharging balance factor is i Cannot exceed k max , that is, the first target droop coefficient k iand the second target droop coefficient k i Are less than or equal to k max .

[0102] (4) Power compensation module

[0103] The power compensation module is configured to perform power compensation in a discharge scenario according to the first target droop coefficient, or to perform power compensation in a charging scenario according to the second target droop coefficient.

[0104] According to the droop control principle, the target power calculation formula of the sodium battery pack is:

[0105]

[0106] Among them, P i is the output power of the i-th energy storage unit, discharge is positive and charge is negative; U 0i is the rated voltage of the i-th energy storage unit; U bus is the common bus voltage; k i During discharge, it is the first target droop coefficient, and during charge, it is the second target droop coefficient;

[0107] Power compensation effect:

[0108] 1) Discharge scenario: Battery pack with high SOC k i The smaller the P i The larger it is, the more the battery pack with high SOC discharges and bears more power shortage.

[0109] 2) Charging scenario: Battery pack with low SOC k i The smaller the P i (Negative value, representing charging power) The battery pack with a larger absolute value and lower SOC is charged more and absorbs excess power first.

[0110] The controller sets the output power P of the i-th energy storage unit to i Convert to current command And sent to the converter PCS of the i-th energy storage unit to control its charging and discharging current.

[0111] (5) SOC balancing module

[0112] The SOC balancing module is used to calculate the average SOC of the energy storage unit in each cycle, and adjust the first target droop coefficient or the second target droop coefficient according to the average SOC to achieve SOC balance feedback regulation.

[0113] The average SOC of the energy storage unit is calculated every cycle. The calculation formula is:

[0114]

[0115] Among them, S OCavg is the average SOC of the energy storage unit, C i is the energy storage unit capacity, and evaluates the deviation of the energy storage unit SOC from the average value:

[0116] If the energy storage unit S OCi >S OCavg +ΔS OC , ΔS OC Set to 5% and further reduce the first target droop coefficient k in the next discharge cycle i , or further increase the second target droop coefficient k during the next charging cycle i , to enhance its more discharge / less charge;

[0117] If the energy storage unit S OCi OCavg -ΔS OC , ΔS OC Set to 5% and further reduce the second target droop coefficient k during the next charging cycle i , or further increase the first target droop coefficient k in the next cycle discharge i , to enhance its more charging / less discharging.

[0118] (6) Real-time monitoring feedback module

[0119] The real-time monitoring feedback module is used to trigger an emergency shutdown and freeze the power distribution of the sodium battery group when the detected terminal voltage of the sodium battery group exceeds a safe range or the charge and discharge current exceeds a rated value.

[0120] Real-time monitoring of the sodium battery terminal voltage U in the energy storage unit i , and when the sodium battery terminal voltage U i Exceeding the safety range (the terminal voltage of the sodium battery pack during discharge U i max , or the terminal voltage U of the sodium battery pack during charging i >U min ), or when the charge and discharge current exceeds the rated value, an emergency shutdown is triggered, and a fault is reported and the power distribution of the sodium battery pack of the energy storage unit is frozen.

[0121] The present invention introduces the SOC of the battery pack into the droop coefficient. When the energy storage unit is discharging, the battery pack with a larger SOC bears more discharge power, and when charging, the battery pack with a smaller SOC bears more charging power. In addition, the droop coefficient is dynamically adjusted according to the SOC during the charging and discharging process, thereby achieving reasonable power distribution and balanced control of the SOC of each energy storage unit, thereby improving system stability and battery life.

[0122] ​​It should be noted that, in this document, the terms "comprises," "includes," or any other variations thereof are intended to encompass non-exclusive inclusion, such that a process, apparatus, article, or method comprising a series of elements includes not only those elements but also other elements not explicitly listed, or elements inherent to such process, apparatus, article, or method. In the absence of further limitations, an element defined by the phrase "comprising a ..." does not exclude the presence of other identical elements in the process, apparatus, article, or method comprising the element.

[0123] The above description is only a preferred embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structure or equivalent process transformation made by using the contents of the present invention description and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A power balance and dynamic compensation system based on sodium battery energy storage, characterized in that: The energy storage unit is composed of a sodium battery pack, and the system includes a region division module, a discharge calculation module, a charge calculation module, a power compensation module, a SOC equalization module, and a real-time monitoring feedback module connected in sequence; The area division module is used to divide the charge and discharge of the sodium battery pack into five working areas according to the SOC value of the sodium battery pack; wherein the working areas include a prohibited discharge area, a restricted discharge area, a free charge and discharge area, a restricted charge area, and a prohibited charge area; The discharge calculation module is used to calculate a first target droop coefficient according to the real-time SOC value of the energy storage unit and a discharge balancing factor, so as to perform adaptive droop control during discharge according to the first target droop coefficient; The charging calculation module is used to calculate a second target droop coefficient according to the real-time SOC value of the energy storage unit and the charging balancing factor, so as to perform adaptive droop control during charging according to the second target droop coefficient; The power compensation module is configured to perform power compensation in a discharge scenario according to the first target droop coefficient, or perform power compensation in a charging scenario according to the second target droop coefficient; The SOC balancing module is used to calculate the average SOC of the energy storage unit in each cycle, and adjust the first target droop coefficient or the second target droop coefficient according to the average SOC to achieve SOC balance feedback regulation; The real-time monitoring feedback module is used to trigger an emergency shutdown and freeze the power distribution of the sodium battery group when the detected terminal voltage of the sodium battery group exceeds a safe range or the charge and discharge current exceeds a rated value.

2. The power balancing and dynamic compensation system based on sodium battery energy storage according to claim 1 is characterized in that: In the area division module, Assume that the SOC of the sodium battery pack at the initial time t0 is S OC0 , when the sodium battery pack is charged and discharged, the SOC at any time t is: Among them, S OC is the SOC value of the sodium battery pack at time t, Q is the maximum capacity of the sodium battery pack that can store charge, P bess The power used to charge or discharge the sodium battery pack; when charging, P bess <0, when discharging, P bess >0; The charge and discharge of sodium battery packs are divided into five working areas according to the SOC value: Discharge prohibited area: SOC is between 0% and S OC1 , the battery is not allowed to discharge at this time; Restricted discharge area: SOC in S OC1 and S OC2 In this area, as the SOC value decreases, the discharge of the battery is gradually limited; Free charge and discharge area: SOC in S OC2 and S OC3 There is no restriction on battery charge and discharge at this time; Restricted charging area: SOC in S OC3 and S OC4 In this area, as the SOC value increases, the battery charging is gradually restricted; Prohibited charging area: SOC between S OC4 To 100%, the battery is not allowed to charge; Among them, S OC1 、S OC2 、S OC3 、S OC4 The value of S is determined by the parameters of the battery pack itself. OC1 The value range of S is 5% to 10%. OC2 The value range of S is 40% to 50%. OC3 The value range of S is 50% to 60%. OC4 The value range is 90% to 95%.

3. The power balancing and dynamic compensation system based on sodium battery energy storage according to claim 2 is characterized in that: In the discharge calculation module, When the i-th energy storage unit is discharged, the expression for determining the droop coefficient is: Among them, S OCi is the SOC value of the i-th energy storage unit, k0 is the initial value of the droop coefficient, k max is the maximum value of the droop coefficient; and according to S OCi The calculation formula for determining the discharge balance factor is: Among them, δ i is the discharge balance factor, S OCavr is the average SOC value of m energy storage units, ΔS OCi is the S of the i-th energy storage unit OCi With the average value S OCavr The difference between the two, a is the difference adjustment coefficient of the equalization factor, and b is the power exponential adjustment coefficient of the equalization factor; The energy storage unit is based on the droop coefficient k' i and discharge balance factor δ i Multiply to get the first target droop coefficient k i .

4. The power balancing and dynamic compensation system based on sodium battery energy storage according to claim 3 is characterized in that: In the charging calculation module, When the i-th energy storage unit is charged, the expression for determining the droop coefficient is: Among them, S OCi is the SOC value of the i-th energy storage unit; and according to S OCi The calculation formula for determining the charge equalization factor is: Among them, γ i is the charging balancing factor; the energy storage unit is based on the droop coefficient k" i and the charge balancing factor γ i Multiply to get the second target droop coefficient k i .

5. The power balancing and dynamic compensation system based on sodium battery energy storage according to claim 4 is characterized in that: The maximum value of the droop coefficient k max Defined as: Among them, P s is the rated capacity of the energy storage unit, ΔV dcmax is the maximum allowable DC voltage deviation; According to the maximum value of the droop coefficient k max The range of the initial value k0 of the droop coefficient is determined to be: 0.1k max ≤k0≤0.3k max ; The first target droop coefficient k i and the second target droop coefficient k i Are less than or equal to k max .

6. The power balancing and dynamic compensation system based on sodium battery energy storage according to claim 5 is characterized in that: In the power compensation module, According to the droop control principle, the target power calculation formula of the sodium battery pack is: Among them, P i is the output power of the i-th energy storage unit, discharge is positive and charge is negative; U 0i is the rated voltage of the i-th energy storage unit; U bus is the common bus voltage; k i During discharge, it is the first target droop coefficient, and during charge, it is the second target droop coefficient; The controller sets the output power P of the i-th energy storage unit to i Convert to current command And sent to the converter PCS of the i-th energy storage unit to control its charging and discharging current.

7. The power balancing and dynamic compensation system based on sodium battery energy storage according to claim 6 is characterized in that: In the SOC balancing module, The average SOC of the energy storage unit is calculated every cycle. The calculation formula is: Among them, S OCavg is the average SOC of the energy storage unit, C i is the energy storage unit capacity, and evaluates the deviation of the energy storage unit SOC from the average value: If the energy storage unit S OCi >S OCavg +ΔSOC, further reducing the first target droop coefficient k during the next discharge cycle i , or further increase the second target droop coefficient k during the next charging cycle i , to enhance its more discharge / less charge; If the energy storage unit S OCi OCavg -ΔSOC, further reduce the second target droop coefficient k during the next charging cycle i , or further increase the first target droop coefficient k in the next cycle discharge i , to enhance its more charging / less discharging.​ 8. The power balancing and dynamic compensation system based on sodium battery energy storage according to claim 7 is characterized in that: In the real-time monitoring feedback module, Real-time monitoring of the sodium battery terminal voltage U in the energy storage unit i , and when the sodium battery terminal voltage U i When the safety range is exceeded or the charge / discharge current exceeds the rated value, an emergency shutdown is triggered, a fault is reported, and the power distribution of the sodium battery pack of the energy storage unit is frozen; wherein, the safety range is: the sodium battery pack terminal voltage U i max , or the terminal voltage U of the sodium battery pack during charging i >U min .​

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