Energy storage control method and fire storage combined AGC frequency modulation system

Abstract

The application discloses a kind of energy storage control method and fire storage combined AGC frequency modulation system.Energy storage control method includes: obtaining the main road apparent power of grid main road, main road reactive power and main road active power, and thus obtaining the main road available power of grid main road;Obtain the branch apparent power of each grid branch, branch reactive power and branch active power, and thus obtain the branch available power corresponding to grid branch;Obtain the battery charging power when each battery energy storage unit connected to grid branch is charged;According to the main road available power, branch available power and battery charging power, the maximum available charging power corresponding to each battery energy storage unit is obtained and power distribution is carried out.The active power, reactive power and apparent power of grid main road and branch are used to obtain the available charging power of battery energy storage unit, which can ensure optimal charging efficiency without overload.

Description

Technical Field

[0001] This application relates to the field of power generation and energy storage, and in particular to an energy storage control method and a combined thermal power and energy storage AGC frequency regulation system. Background Technology

[0002] In related technologies, grid overload is typically prevented by setting a maximum current for each grid branch. When the branch current exceeds this maximum value, the grid control system reports an overload to the energy management system, which then reduces the charging power of the battery storage units to prevent overload. This method only considers the active current of the branch. Without an overload, the increase in charging power for each battery storage unit is difficult to predict. The energy management system can only reduce the charging power to avoid overload. Therefore, when setting the maximum current for a branch using this method, sufficient margin must be maintained to ensure safety, but this results in a lower maximum charging power for the battery storage units. Summary of the Invention

[0003] This application aims to address at least one of the technical problems existing in the prior art. To this end, this application proposes an energy storage control method that explicitly obtains the increaseable charging power of the battery energy storage unit through the active power, reactive power, and apparent power of the main power and branch power of the power grid, thereby ensuring optimal charging efficiency without overload.

[0004] This application also proposes a combined thermal energy storage AGC frequency regulation system that applies the above-mentioned energy storage control method.

[0005] An energy storage control method according to a first aspect of this application includes: acquiring the apparent power, reactive power, and active power of a main power grid; obtaining the main power grid's scalable power based on the apparent power, reactive power, and active power; acquiring the branch apparent power, reactive power, and active power of each power grid branch; obtaining the branch scalable power corresponding to the power grid branch based on the branch apparent power, reactive power, and active power; acquiring the battery charging power when each battery energy storage unit connected to the power grid branch is charging; and obtaining the maximum chargeable power corresponding to each battery energy storage unit based on the main power grid's scalable power, branch scalable power, and battery charging power, and then allocating the power accordingly.

[0006] The energy storage control method according to the embodiments of this application has at least the following beneficial effects: the increaseable charging power of the battery energy storage unit can be clearly obtained by the active power, reactive power and apparent power of the main circuit and branch circuit of the power grid, and the optimal charging efficiency can be guaranteed without overload.

[0007] According to some embodiments of this application, the step of obtaining the main road's potential power increase based on the main road's apparent power, the main road's reactive power, and the main road's active power includes: squaring the main road's apparent power to obtain a first squared value; squaring the main road's reactive power to obtain a second squared value; calculating the difference between the first squared value and the second squared value to obtain a first difference; taking the square root of the first difference to obtain a first square root value; and calculating the difference between the first square root value and the main road's active power and taking its opposite to obtain the main road's potential power increase.

[0008] According to some embodiments of this application, the power grid branch includes a first branch and a second branch, and the battery energy storage unit includes a first energy storage unit and a second energy storage unit, wherein the first energy storage unit is connected to the first branch and the second energy storage unit is connected to the second branch.

[0009] According to some embodiments of this application, the step of obtaining the apparent power, reactive power and active power of each power grid branch includes: obtaining the first apparent power, first reactive power and first active power of the first branch; and obtaining the second apparent power, second reactive power and second active power of the second branch.

[0010] According to some embodiments of this application, the step of obtaining the branch's potential power increase based on the branch's apparent power, reactive power, and active power includes: squaring the first apparent power and the second apparent power to obtain a third squared value and a fourth squared value; squaring the first reactive power and the second reactive power to obtain a fifth squared value and a sixth squared value; calculating the difference between the third squared value and the fifth squared value to obtain a second difference value; calculating the difference between the fourth squared value and the sixth squared value to obtain a third difference value; taking the square root of the second difference value and the third difference value to obtain a second square root value and a third square root value; calculating the difference between the second square root value and the first active power and taking its opposite to obtain a first potential power increase value; and calculating the difference between the third square root value and the second active power and taking its opposite to obtain a second potential power increase value.

[0011] According to some embodiments of this application, the step of obtaining the battery charging power when each battery energy storage unit connected to each power grid branch is charging includes: obtaining the first charging power when the first energy storage unit is charging; and obtaining the second charging power when the second energy storage unit is charging.

[0012] According to some embodiments of this application, the step of obtaining the maximum rechargeable power of each battery energy storage unit based on the main road's increaseable power, the branch road's increaseable power, and the battery charging power, and then allocating power, includes: calculating the sum of the first increaseable power and the second increaseable power to obtain the total increaseable power of the branch road; calculating the ratio of the first increaseable power to the total increaseable power to obtain a first proportional coefficient, and calculating the ratio of the second increaseable power to the total increaseable power to obtain a second proportional coefficient; calculating the product of the main road's increaseable power and the first proportional coefficient to obtain a first allocated power, and calculating the product of the main road's increaseable power and the second proportional coefficient to obtain a second allocated power; selecting the larger value between the first increaseable power and the first allocated power as a first comparison value, and calculating the sum of the first comparison value and the first charging power to obtain a first rechargeable power; selecting the larger value between the second increaseable power and the second allocated power as a second comparison value, and calculating the sum of the second comparison value and the second charging power to obtain a second rechargeable power; and controlling the first energy storage unit and the second energy storage unit to charge at the first rechargeable power and the second rechargeable power, respectively.

[0013] According to some embodiments of this application, the method further includes: obtaining the battery discharge power, preset discharge coefficient, and preset discharge threshold of each battery energy storage unit during discharge; obtaining the actual power of each power grid branch corresponding to the battery energy storage unit; obtaining the maximum discharge power of the battery energy storage unit based on the battery discharge power, the actual power, the preset discharge coefficient, and the preset discharge threshold; and controlling the battery energy storage unit to discharge at the maximum discharge power.

[0014] According to some embodiments of this application, the step of obtaining the maximum discharge power of the battery energy storage unit based on the battery discharge power, the actual power, the preset discharge threshold, and the preset discharge coefficient includes: calculating the product of the actual power and the preset discharge coefficient to obtain a first discharge power; calculating the difference between the actual power and the preset discharge threshold to obtain a second discharge power; selecting the smaller value between the first discharge power and the second discharge power as the actual discharge power; and calculating the sum of the actual discharge power and the battery discharge power to obtain the maximum discharge power.

[0015] A combined thermal power generation and energy storage AGC frequency regulation system according to a second aspect of this application includes: a thermal power unit for generating electricity; a battery energy storage system connected to the thermal power unit, the battery energy storage system including multiple battery energy storage units, each battery energy storage unit connected to a power grid branch; and an energy management system connected to both the thermal power unit and the battery energy storage system, the energy management system being used for AGC frequency regulation, and the energy management system also being used to execute the energy storage control method of the first aspect of this application.

[0016] Additional aspects and advantages of this application will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of this application. Attached Figure Description

[0017] The present application will be further described below with reference to the accompanying drawings and embodiments, wherein:

[0018] Figure 1 This is a flowchart of one embodiment of the energy storage control method of this application;

[0019] Figure 2 for Figure 1 The flowchart of step S200 in one embodiment is shown;

[0020] Figure 3 This is a schematic diagram of one embodiment of the power grid described in this application;

[0021] Figure 4 for Figure 1 The flowchart of step S300 in one embodiment is shown;

[0022] Figure 5 for Figure 1 The flowchart of step S400 in one embodiment is shown;

[0023] Figure 6 for Figure 1 The flowchart of step S500 in one embodiment is shown;

[0024] Figure 7 for Figure 1 The flowchart of step S600 in one embodiment is shown;

[0025] Figure 8 This is a flowchart of another embodiment of the energy storage control method of this application;

[0026] Figure 9 for Figure 8 The flowchart of step S900 in one embodiment is shown;

[0027] Figure 10This is a block diagram of one embodiment of the combined fire and energy storage AGC frequency modulation system of this application.

[0028] Figure label:

[0029] First energy storage unit 100, second energy storage unit 200, thermal power unit 300, battery energy storage system 400, energy management system 500. Detailed Implementation

[0030] The embodiments of this application are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain this application, and should not be construed as limiting this application.

[0031] In the description of this application, "several" means one or more, "multiple" means two or more, "greater than," "less than," and "exceeding" are understood to exclude the stated number, while "above," "below," and "within" are understood to include the stated number. The use of "first" and "second" in the description is merely for distinguishing technical features and should not be construed as indicating or implying relative importance, or implicitly indicating the number of indicated technical features, or implicitly indicating the order of the indicated technical features.

[0032] In the description of this application, unless otherwise expressly defined, terms such as "setup," "installation," and "connection" should be interpreted broadly, and those skilled in the art can reasonably determine the specific meaning of the above terms in this application in conjunction with the specific content of the technical solution.

[0033] The energy storage control method of this application embodiment can be used in a combined thermal power and energy storage AGC frequency regulation system, and can protect the battery energy storage system that assists in the AGC frequency regulation of thermal power units. AGC (Automatic Generation Control) is a technology in the power system that regulates the active power output of multiple generators in different power plants to respond to load changes. It is an important function in the energy management system. It controls the output of frequency regulation units to meet the ever-changing power demand of users and keep the system in an economical operating state.

[0034] In recent years, lithium battery technology has developed rapidly, and battery energy storage systems, as one application direction of lithium batteries, have important application scenarios on the generation side, grid side, and user side. Traditional thermal power unit AGC frequency regulation has slow adjustment rate and response speed, and low regulation accuracy, while battery energy storage systems have the characteristics of fast response speed and high regulation accuracy. Therefore, battery energy storage systems are now widely used to assist thermal power unit AGC frequency regulation, thereby improving the AGC regulation performance of thermal power units. In a combined thermal power and energy storage AGC frequency regulation system, when the battery energy storage system is charging, it acts as a power-consuming device, and the energy management system controls its charging power to not exceed the rated power of the main and branch lines of the power grid to prevent overload. When the battery energy storage system is discharging, it acts as a power-generating device, supplying power to the load along with the grid branch lines. To prevent triggering relay one-way protection or reverse transmission of unstable power to the grid, affecting the normal operation of the thermal power unit or the power grid, the energy management system controls the discharge power of the battery energy storage system to not exceed the power of the branch line load.

[0035] In related technologies, grid overload is typically prevented by setting a maximum current for grid branches. When the branch current exceeds this maximum value, the grid control system reports an overload status to the energy management system, which then reduces the charging power of the battery storage units to prevent overload. This method only considers the active current of the branch. Without an overload, the increase in charging power for each battery storage unit is difficult to predict. The energy management system can only reduce the charging power to avoid overload. Therefore, setting the maximum current for a branch must allow for sufficient margin to ensure safety, resulting in a lower maximum charging power for the battery storage units. When a battery storage unit discharges, if its discharge power exceeds the power required by the corresponding branch's load, the excess discharge power may flow back to the high-voltage side of the grid, triggering relay protection or affecting the normal operation of thermal power units and the grid. Existing technologies typically prevent backflow by setting a minimum current for grid branches. When the branch current is less than this minimum value, the grid control system reports a load limiting status to the energy management system, which then reduces the discharge power of the battery storage units to prevent backflow. Without load limiting, the increase in discharge power of each battery energy storage unit is difficult to predict. The energy management system can only reduce the discharge power of the battery energy storage unit under load limiting conditions. Therefore, sufficient margin must be reserved when setting the minimum current of the branch to ensure safety, resulting in a lower maximum discharge power of the battery energy storage unit.

[0036] Based on this, this application proposes an energy storage control method that can ensure the optimal operating efficiency of the battery energy storage system without overload or reverse feed.

[0037] Some embodiments, refer to Figure 1 Energy storage control methods include:

[0038] S100: Obtain the apparent power, reactive power and active power of the main power grid;

[0039] S200, based on the apparent power, reactive power and active power of the main line, the main line can be increased power of the main line of the power grid.

[0040] S300, obtain the branch apparent power, branch reactive power and branch active power of each power grid branch;

[0041] S400, based on the branch apparent power, branch reactive power and branch active power, obtains the branch power that can be increased corresponding to the grid branch;

[0042] S500: Obtain the battery charging power when each battery energy storage unit connected to the power grid branch is charging.

[0043] S600 obtains the maximum chargeable power corresponding to each battery energy storage unit based on the main road's increaseable power, the branch road's increaseable power, and the battery charging power, and then allocates the power.

[0044] It should be noted that multiple battery energy storage units constitute a battery energy storage system, and each battery energy storage unit is connected to a branch of the power grid. The above steps are applied when the battery energy storage units are charging.

[0045] For step S100, apparent power is a quantity representing the capacity of AC electrical equipment, equal to the product of the effective value of voltage and the effective value of current. Multiplying this by the power factor equals active power, thus determining the maximum active power obtainable under given voltage and current conditions. Reactive power refers to the energy absorbed from the power source by the electric or magnetic field in an AC circuit with reactance during a portion of a cycle and released during another portion. The average power is zero throughout the entire cycle, but energy is constantly exchanged between the power source and reactive components (capacitors, inductors). The maximum value of this exchange rate is the "reactive power." Active power refers to the actual AC electrical energy generated or consumed per unit time; it is the average power within a cycle.

[0046] For step S200, apparent power is composed of a mixture of reactive power and active power. The main line increaseable power is the active power that the main line can increase. Therefore, the main line increaseable power can be obtained by subtracting the reactive power portion and the current real-time active power portion from the apparent power.

[0047] For steps S300 and S400, the method for calculating the branch power increase of a power grid branch is similar to the method for calculating the main power increase of a power grid main line. The branch power increase is the active power that the branch can add. The branch power increase is usually different for different branches, so they need to be calculated separately.

[0048] For step S500, the battery charging power of the battery energy storage unit corresponding to different power grid branches is usually different, and they need to be tested separately.

[0049] In step S600, the sum of the actual increased power of each branch is the actual increased power of the main circuit. The sum of the increaseable power of each branch may be greater than the increaseable power of the main circuit. Therefore, it is possible that the actual increased power of some branches is greater than their individual increaseable power, while the total sum of the actual increased power of the branches is less than or equal to the increaseable power of the main circuit. In other words, if some branches are overloaded, the main circuit may not be overloaded. Similarly, it is possible that the actual increased power of each branch is less than or equal to their individual increaseable power, while the total sum of the actual increased power of the branches is greater than the increaseable power of the main circuit. In other words, if the branches are not overloaded, the main circuit may be overloaded. It is also understandable that both the main circuit and branches may be overloaded. This embodiment uses a power allocation method, distributing the increaseable power of the main circuit according to the proportion of the increaseable power of each branch to the total increaseable power of the branches, thereby ensuring that neither the main circuit nor the branches are overloaded. The sum of the additional power allocated to each branch and the battery charging power of the corresponding battery energy storage unit is the maximum chargeable power. In other words, the additional power allocated to each branch is the additional charging power of the corresponding battery energy storage unit. Charging the battery energy storage unit at the maximum chargeable power can greatly enhance the utilization efficiency of the battery energy storage unit.

[0050] The energy storage control method of this application embodiment has at least the following beneficial effects: the increaseable charging power of the battery energy storage unit can be clearly obtained by the active power, reactive power and apparent power of the main circuit and branch circuit of the power grid, and the optimal charging efficiency can be guaranteed without overload.

[0051] Some embodiments, refer to Figure 2 The steps for determining the potential increase in power of the main line based on the apparent power, reactive power, and active power of the main line include:

[0052] S210 squares the apparent power of the main road to obtain the first squared value;

[0053] S220 squares the reactive power of the main road to obtain the second squared value;

[0054] S230 calculates the difference between the first squared value and the second squared value to obtain the first difference;

[0055] S240 takes the square root of the first difference to obtain the first square root value;

[0056] S250 calculates the difference between the first square root value and the active power of the main road and takes the opposite number to obtain the increase in power of the main road.

[0057] Let apparent power be S, reactive power be Q, and active power be P. In an AC circuit, the relationship between apparent power, reactive power, and active power of the same line is: S 2 =Q 2 +P 2 It should be noted that, in the embodiments of this application, the power of the battery energy storage unit during charging is specified as a negative value, and the power during discharging is specified as a positive value.

[0058] For steps S210, S220, S230, and S240, first calculate the squares of the apparent power and reactive power of the main circuit, then calculate the difference between the two squares to obtain the square of the maximum active power of the main circuit. The first square root obtained by taking the square root is the maximum active power of the main circuit.

[0059] For step S250, the difference between the maximum active power of the main circuit and the current active power of the main circuit is the main circuit's potential power increase. The main circuit's potential power increase is one of the factors that determines the battery energy storage unit's ability to increase charging power, therefore it is taken as a negative value.

[0060] It should be noted that the apparent power of the main line in this embodiment is the rated power, while the reactive power and active power of the main line are variable real-time power.

[0061] The specific calculation formula for calculating the power increase of the main road in this embodiment is as follows:

[0062]

[0063] In equation (1), ΔfPb_main represents the main circuit's increaseable power, fSe_main represents the rated main circuit's apparent power, fQ_main represents the real-time main circuit's reactive power, and fP_main represents the real-time main circuit's active power.

[0064] Some embodiments, refer to Figure 3 The power grid branch includes a first branch and a second branch, and the battery energy storage unit includes a first energy storage unit 100 and a second energy storage unit 200. The first energy storage unit 100 is connected to the first branch, and the second energy storage unit 200 is connected to the second branch. The first branch is branch A, and the second branch is branch B. In one embodiment, the power grid branch may also include three or more branches. In actual power supply grids, there are usually more than two power grid branches.

[0065] Some embodiments, refer to Figure 4 The steps for obtaining the apparent power, reactive power, and active power of each power grid branch include:

[0066] S310, obtain the first apparent power, first reactive power and first active power of the first branch;

[0067] S320, obtains the second apparent power, second reactive power and second active power of the second branch.

[0068] For steps S310 and S320, the electrical loads of different branches are different, so it is necessary to obtain their apparent power, reactive power, and active power separately. Understandably, if there are more than three branches in the power grid, it is also necessary to obtain the power data for each branch separately.

[0069] Some embodiments, refer to Figure 5 The steps for obtaining the branch's potential power increase based on the branch's apparent power, reactive power, and active power include:

[0070] S410, square the first apparent power and the second apparent power respectively to obtain the third square value and the fourth square value;

[0071] S420, square the first reactive power and the second reactive power respectively to obtain the fifth square value and the sixth square value;

[0072] S430, calculate the difference between the third square value and the fifth square value to obtain the second difference value, and calculate the difference between the fourth square value and the sixth square value to obtain the third difference value;

[0073] S440, take the square root of the second difference and the third difference respectively to obtain the second square root value and the third square root value;

[0074] S450, calculate the difference between the second square root value and the first active power and take the opposite number to obtain the first increaseable power;

[0075] S460, calculate the difference between the third square root value and the second active power and take the opposite number to obtain the second increaseable power.

[0076] For steps S410, S420, S430, and S440, first calculate the squares of the apparent power and reactive power of the first branch, then calculate the difference between these two squares to obtain the square of the maximum active power of the first branch, and finally take the second square root to obtain the maximum active power of the first branch. Similarly, first calculate the squares of the apparent power and reactive power of the second branch, then calculate the difference between these two squares to obtain the square of the maximum active power of the second branch, and finally take the third square root to obtain the maximum active power of the second branch.

[0077] For steps S450 and S460, the difference between the maximum active power of the first branch and the second branch and the current active power of the corresponding branch is the potential power increase of each branch, namely the first potential power increase and the second potential power increase. Similarly, the first potential power increase and the second potential power increase are negative.

[0078] The specific calculation formulas for the power increase of the first branch (branch A) and the second branch (branch B) in this embodiment are as follows:

[0079]

[0080]

[0081] In equation (2), ΔfPb_A represents the first increaseable power, fSe_A represents the rated first apparent power, fQ_A represents the real-time first reactive power, and fP_A represents the real-time first active power.

[0082] In equation (3), ΔfPb_B represents the second increaseable power, fSe_B represents the rated second apparent power, fQ_B represents the real-time second reactive power, and fP_B represents the real-time second active power.

[0083] In an illustrative embodiment, the number of power grid branches can be three or more, and the calculation method for the power increase of each branch is the same as the steps described above.

[0084] Some embodiments, refer to Figure 6 The steps for obtaining the battery charging power of each battery storage unit connected to each power grid branch during charging include:

[0085] S510, obtain the first charging power when the first energy storage unit is charging;

[0086] S520, obtain the second charging power when the second energy storage unit is charging.

[0087] For steps S510 and S520, the charging power of the battery energy storage unit in different branches is different, and it needs to be detected and calculated separately.

[0088] Some embodiments, refer to Figure 7 The steps of obtaining the maximum chargeable power of each battery energy storage unit based on the main road's scalable power, the branch road's scalable power, and the battery's charging power, and then allocating power, include:

[0089] S610, calculate the sum of the first increaseable power and the second increaseable power to obtain the total increaseable power of the branch;

[0090] S620, calculate the ratio of the first increaseable power to the total increaseable power to obtain the first proportional coefficient, and calculate the ratio of the second increaseable power to the total increaseable power to obtain the second proportional coefficient;

[0091] S630, calculate the product of the main road's upgradable power and the first proportional coefficient to obtain the first allocated power, and calculate the product of the main road's upgradable power and the second proportional coefficient to obtain the second allocated power;

[0092] S640, Select the larger value between the first increaseable power and the first allocated power as the first comparison value, calculate the sum of the first comparison value and the first charging power to obtain the first chargeable power;

[0093] S650, select the larger value between the second increaseable power and the second allocated power as the second comparison value, calculate the sum of the second comparison value and the second charging power to obtain the second chargeable power;

[0094] S660 controls the first energy storage unit and the second energy storage unit to charge at the first rechargeable power and the second rechargeable power, respectively.

[0095] For step S610, the power increase of each branch is added together to obtain the total power increase of all branches.

[0096] For step S620, the first proportionality coefficient and the second proportionality coefficient each represent the proportion of the power increase that the first branch and the second branch can achieve among all branches. The calculation formulas for the first proportionality coefficient and the second proportionality coefficient in this embodiment are as follows:

[0097]

[0098]

[0099] In equations (4) and (5), k1 represents the first proportionality coefficient, k2 represents the second proportionality coefficient, ΔfPb_A represents the first achievable power, and ΔfPb_B represents the second achievable power.

[0100] In step S630, the power increase of the main line is allocated according to the proportional coefficient of each branch, so as to ensure that the sum of the actual power increase of each branch does not exceed the power increase of the main line, thus avoiding the overload of the main line.

[0101] In steps S640 and S650, the allocated power to each branch is compared with the increaseable power of each branch. Since both the allocated power value and the increaseable power value are defined as negative values, the larger value is taken as the actual increaseable power, i.e., the smaller absolute value is taken as the actual increaseable power. This ensures that the actual increase in power of each branch does not exceed its allowable increase range, avoiding branch overload. The sum of the actual increaseable power of each branch and its original battery energy storage unit charging power is the maximum chargeable power of the battery energy storage unit of each branch, i.e., the first chargeable power and the second chargeable power.

[0102] The specific calculation formulas for the first chargeable power and the second chargeable power in this embodiment are as follows:

[0103] fPmin_A=fPb_A+max(ΔfPb_A,ΔfPb_main*k1) (6)

[0104] fPmin_B=fPb_B+max(ΔfPb_B,ΔfPb_main*k2) (7)

[0105] In equations (6) and (7), fPmin_A represents the first chargeable power, fPb_A represents the first charging power, ΔfPb_A represents the first boostable power, ΔfPb_main represents the boostable power of the main circuit, k1 represents the first proportional coefficient, fPmin_B represents the second chargeable power, fPb_B represents the second charging power, ΔfPb_B represents the second boostable power, k2 represents the second proportional coefficient, max represents taking the larger value, and both fPmin_A and fPmin_B are negative values.

[0106] In step S660, under the premise of ensuring that neither the main circuit nor the branch circuit is overloaded, the battery energy storage units of the first branch circuit and the second branch circuit are charged at the maximum chargeable power, thus ensuring the best charging efficiency of the battery energy storage units.

[0107] In an illustrative embodiment, there can be three or more power grid branches. The process of distributing the power upscaling capacity of the main line to each branch is similar to the steps described above and will not be repeated here.

[0108] Some embodiments, refer to Figure 8 Energy storage control methods also include:

[0109] S700, obtains the battery discharge power, preset discharge coefficient and preset discharge threshold when each battery energy storage unit discharges;

[0110] S800, obtains the actual power of each grid branch corresponding to the battery energy storage unit;

[0111] S900 obtains the maximum discharge power of the battery energy storage unit based on the battery discharge power, actual power, preset discharge coefficient and preset discharge threshold.

[0112] S1000 controls the battery energy storage unit to discharge at its maximum discharge power.

[0113] It should be noted that the steps in this embodiment are applied when the battery energy storage unit is discharging. In the embodiments of this application, the power of the battery energy storage unit during charging is defined as a negative value, and the power during discharging is defined as a positive value.

[0114] For steps S700 and S800, the battery discharge power is the real-time discharge power of the battery energy storage unit. To ensure that the corresponding branch is always in a power supply state, the increased discharge power of the battery energy storage unit must not exceed a certain proportion of the current actual power of the branch. This proportion is the preset discharge coefficient. In this embodiment, the preset discharge coefficient is set to 0.95, which is determined in consultation with the power plant. When the discharge power of the battery energy storage unit increases, the power supplied by the branch will decrease because the power consumed by the electrical load remains stable. If the power supply of the branch is too low, reverse power transmission may occur. Therefore, a preset discharge threshold is set to ensure that the power supply of the branch is not less than this threshold, thus preventing the battery energy storage unit from transmitting power back to the main line via the branch. Typically, this preset discharge threshold is 0.5MV.

[0115] For steps S900 and 1000, after calculating the maximum discharge power of the battery energy storage unit in this branch, the battery energy storage unit is controlled to discharge at this power. This ensures that the power supply function of the battery energy storage unit is fully utilized, reducing the pressure on the power plant, while preventing reverse power transmission.

[0116] Some embodiments, refer to Figure 9 The steps for obtaining the maximum discharge power of the battery energy storage unit based on the battery discharge power, actual power, preset discharge threshold, and preset discharge coefficient include:

[0117] S910, calculate the product of the actual power and the preset discharge coefficient to obtain the first dischargeable power;

[0118] S920, calculate the difference between the actual power and the preset discharge threshold to obtain the second dischargeable power;

[0119] S930, select the smaller value between the first amplifiable power and the second amplifiable power as the actual amplifiable power;

[0120] S940 calculates the sum of the actual discharge power and the battery discharge power to obtain the maximum discharge power.

[0121] For steps S910 and S920, the first dischargeable power and the second dischargeable power are the dischargeable power that can be increased by the branch considering only the preset discharge coefficient and the preset discharge threshold, respectively.

[0122] For step S930, by selecting the smaller value between the first dischargeable power and the second dischargeable power, the maximum increaseable discharge power of the battery energy storage unit can be obtained while ensuring that the branch is in a power supply state, which is the actual increaseable discharge power.

[0123] For step S940, the current discharge power of the battery energy storage unit is added to its maximum increase discharge power to obtain the maximum discharge power of the battery energy storage unit.

[0124] Specific examples, embodiments of this application Figure 3 The formula for calculating the maximum discharge power of the first energy storage unit 100 in the first branch (branch A) shown is:

[0125] fPmax_A=fPb_a+min(0.95fP,fP-0.5) (8)

[0126] In equation (8), fPmax_A represents the maximum discharge power of the energy storage unit of branch A, fPb_a represents the real-time battery discharge power of the first energy storage unit 100, fP represents the actual power supplied by branch A, and min represents taking the smaller value.

[0127] The calculation method for the maximum discharge power of the second energy storage unit 200 in branch B is similar to that in branch A, and will not be repeated here. It is understandable that if there are three or more branches in the power grid, the calculation method for the maximum discharge power of the battery energy storage units in other branches is the same as above.

[0128] Some embodiments, refer to Figure 10 The combined thermal power generation and energy storage AGC frequency regulation system includes: a thermal power unit 300, a battery energy storage system 400, and an energy management system 500. The thermal power unit 300 is used for power generation; the battery energy storage system 400 is connected to the thermal power unit 300 and includes multiple battery energy storage units, each of which is connected to a power grid branch; the energy management system 500 is connected to both the thermal power unit 300 and the battery energy storage system 400, and is used for AGC frequency regulation. The energy management system 500 is also used to execute the energy storage control method of any of the above embodiments.

[0129] The combined thermal energy storage AGC frequency regulation system of this application embodiment can be a system with high energy storage capacity. By considering the influence of factors such as active power, reactive power, apparent power, preset discharge coefficient, and preset discharge threshold, the maximum chargeable power or maximum dischargeable power of each branch battery energy storage unit is predicted under the condition of no overload or reverse feed, so that the energy management system can perform energy control within the maximum chargeable and dischargeable power space and give full play to the auxiliary functions of the battery energy storage system.

[0130] In the description of this application, the references to terms such as "one embodiment," "some embodiments," "illustrative embodiment," or "specific example," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0131] The embodiments of this application have been described in detail above with reference to the accompanying drawings. However, this application is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of this application. Furthermore, unless otherwise specified, the embodiments and features described in the embodiments of this application can be combined with each other.

Claims

1. An energy storage control method, applied to a combined thermal energy storage AGC frequency regulation system, characterized in that, include: Obtain the apparent power, reactive power, and active power of the main power grid; The first squared value is obtained by squaring the apparent power of the main road; Square the reactive power of the main circuit to obtain the second squared value; Calculate the difference between the first squared value and the second squared value to obtain the first difference; Take the square root of the first difference to obtain the first square root value; Calculate the difference between the first square root value and the active power of the main road, and take the opposite number to obtain the increase in power of the main road; Obtain the apparent power, reactive power, and active power of each power grid branch; The branch power increase capability corresponding to the power grid branch is obtained based on the branch apparent power, the branch reactive power, and the branch active power. Obtain the battery charging power when each battery energy storage unit connected to the power grid branch is charging. The maximum chargeable power corresponding to each battery energy storage unit is obtained based on the main circuit's scalable power, the branch circuit's scalable power, and the battery charging power, and power allocation is performed accordingly. Specifically, the maximum chargeable power corresponding to each battery energy storage unit is obtained by allocating the main circuit's scalable power based on the ratio of the branch circuit's scalable power to the sum of the scalable power of all the grid branches, and then adding this scalable power to the battery charging power. Obtain the battery discharge power, preset discharge coefficient, and preset discharge threshold of each battery energy storage unit during discharge; Obtain the actual power of each of the power grid branches corresponding to the battery energy storage unit; The maximum discharge power of the battery energy storage unit is obtained based on the battery discharge power, the actual power, the preset discharge coefficient, and the preset discharge threshold. The battery energy storage unit is controlled to discharge at the maximum discharge power.

2. The energy storage control method according to claim 1, characterized in that, The power grid branch includes a first branch and a second branch, and the battery energy storage unit includes a first energy storage unit and a second energy storage unit. The first energy storage unit is connected to the first branch, and the second energy storage unit is connected to the second branch.

3. The energy storage control method according to claim 2, characterized in that, The steps of obtaining the apparent power, reactive power, and active power of each power grid branch include: Obtain the first apparent power, first reactive power, and first active power of the first branch; Obtain the second apparent power, second reactive power, and second active power of the second branch.

4. The energy storage control method according to claim 3, characterized in that, The step of obtaining the branch's potential power increase based on the branch's apparent power, reactive power, and active power includes: Square the first apparent power and the second apparent power respectively to obtain the third squared value and the fourth squared value; Square the first reactive power and the second reactive power respectively to obtain the fifth square value and the sixth square value; The difference between the third squared value and the fifth squared value is calculated to obtain the second difference value, and the difference between the fourth squared value and the sixth squared value is calculated to obtain the third difference value; Calculate the square roots of the second difference and the third difference to obtain the second square root value and the third square root value respectively; calculate the difference between the second square root value and the first active power and take the opposite number to obtain the first increaseable power. The difference between the third square root value and the second active power is calculated and its opposite is taken to obtain the second increaseable power.

5. The energy storage control method according to claim 4, characterized in that, The step of obtaining the battery charging power of each battery energy storage unit connected to each power grid branch during charging includes: Obtain the first charging power when the first energy storage unit is charging; Obtain the second charging power when the second energy storage unit is charging.

6. The energy storage control method according to claim 5, characterized in that, The step of obtaining the maximum chargeable power of each battery energy storage unit based on the main road's scalable power, the branch road's scalable power, and the battery's charging power, and then allocating the power, includes: Calculate the sum of the first increaseable power and the second increaseable power to obtain the total increaseable power of the branch; A first proportionality coefficient is obtained by calculating the ratio of the first increaseable power to the total increaseable power, and a second proportionality coefficient is obtained by calculating the ratio of the second increaseable power to the total increaseable power. The first allocated power is obtained by multiplying the main road's upscaling power by the first proportional coefficient, and the second allocated power is obtained by multiplying the main road's upscaling power by the second proportional coefficient. The larger value between the first increaseable power and the first allocated power is selected as the first comparison value. The sum of the first comparison value and the first charging power is calculated to obtain the first chargeable power. The larger value between the second increaseable power and the second allocated power is selected as the second comparison value. The sum of the second comparison value and the second charging power is calculated to obtain the second chargeable power. The first energy storage unit and the second energy storage unit are controlled to charge at the first rechargeable power and the second rechargeable power, respectively.

7. The energy storage control method according to claim 1, characterized in that, The step of obtaining the maximum discharge power of the battery energy storage unit based on the battery discharge power, the actual power, the preset discharge threshold, and the preset discharge coefficient includes: The first dischargeable power is obtained by calculating the product of the actual power and the preset discharge coefficient. The difference between the actual power and the preset discharge threshold is calculated to obtain the second dischargeable power; The smaller value between the first amplifiable power and the second amplifiable power is selected as the actual amplifiable power. The maximum discharge power is obtained by calculating the sum of the actual discharge power and the battery discharge power.

8. A combined thermal power and energy storage AGC frequency regulation system, characterized in that, include: Thermal power units, which are used for power generation; A battery energy storage system is connected to the thermal power unit. The battery energy storage system includes multiple battery energy storage units, and each battery energy storage unit is connected to a power grid branch. An energy management system is provided, which is connected to the thermal power unit and the battery energy storage system respectively. The energy management system is used for AGC frequency regulation and is also used to execute the energy storage control method as described in any one of claims 1 to 7.

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