Modular energy storage and consumption collaborative hybrid direct current energy consumption device and control method thereof

Abstract

The application belongs to the technical field of flexible direct current transmission and provides a modular energy storage and consumption collaborative hybrid direct current energy consumption device, which is arranged between a direct current positive bus and a direct current negative bus of a direct current system and comprises an energy storage submodule string, a line inductance L s and an energy consumption submodule string; the energy storage submodule string comprises n energy storage submodules ESM1 to ESM n connected in series; the energy consumption submodule string comprises m energy consumption submodules RSM1 to RSM m connected in series; the energy storage submodule string, the line inductance L s and the energy consumption submodule string are connected in series along a direct current current channel to form a direct current side energy absorption branch, the upper end of the direct current side energy absorption branch is connected to the direct current positive bus, and the lower end of the direct current side energy absorption branch is connected to the direct current negative bus. The application changes a traditional single energy consumption resistor into a controllable energy consumption submodule array and cooperates with the energy storage submodule to realize the functions of energy consumption and energy storage charging and discharging, can better maintain the stability of the bus direct current voltage and absorb surplus power during fault ride-through, and has good reliability and engineering adaptability.

Description

Technical Field

[0001] This application belongs to the field of flexible DC transmission technology, and in particular relates to a modular energy storage and energy consumption co-operation hybrid DC energy consumption device and its control method. Background Technology

[0002] Flexible DC transmission technology is widely used in large-scale offshore wind power transmission over long distances. When a fault occurs in the receiving-end AC system, the active power output of the receiving-end converter drops sharply, while the power on the wind farm side cannot decrease synchronously in a short period of time, leading to a power imbalance between the sending and receiving ends. The surplus power continuously accumulates on the equivalent capacitance of the DC bus and the capacitors of the converter submodules, causing a rapid rise in DC voltage, which may trigger overvoltage protection and threaten the insulation safety of critical equipment such as submarine cables and converter valves. Currently, in engineering practice, DC energy dissipation devices are typically installed on the onshore DC side. By activating energy dissipation resistors, surplus power is quickly dissipated to suppress DC overvoltage and ensure system fault ride-through.

[0003] However, existing DC power-consuming devices dissipate surplus power directly as heat loss, failing to achieve the recovery and utilization of surplus power. Summary of the Invention

[0004] This application provides a modular energy storage and energy consumption co-operation hybrid DC energy consumption device and its control method, which can solve the problem that existing DC energy consumption devices directly dissipate surplus power in the form of heat loss and fail to realize the recovery and utilization of surplus power.

[0005] In a first aspect, embodiments of this application provide a modular energy storage and energy consumption co-operation hybrid DC energy consumption device, which includes an energy storage sub-module string and a line inductance L between the DC positive bus and the DC negative bus of the DC system. s and an energy-consuming submodule string; the energy storage submodule string includes n energy storage submodules ESM1 to ESM1 connected in series. n Where n is a positive integer; the energy-consuming submodule string includes m cascaded energy-consuming submodules RSM1 to RSM m Where m is a positive integer; the energy storage submodule string, the line inductance L s The energy-consuming submodules are connected in series along the DC current channel to form a DC-side energy-absorbing branch. The upper end of the DC-side energy-absorbing branch is connected to the DC positive bus, and the lower end is connected to the DC negative bus.

[0006] In one possible implementation of the first aspect, any of the above-mentioned energy storage submodules ESM k It includes a first switch arm, a second switch arm, a submodule capacitor C, an interface inductor L, and a rechargeable battery energy storage unit U. bk ;

[0007] The first switch arm consists of a switching device T 1k With switching device T 2k The second switch arm is composed of a series connection and consists of a switching device T. 3k With switching device T 4k Composed of series connection;

[0008] The submodule capacitor C is connected across the upper and lower nodes of the energy storage submodule and is connected in parallel with the first switch arm and the second switch arm;

[0009] The midpoint of the first switch arm serves as the first external terminal of the energy storage submodule, and the lower node of the energy storage submodule serves as the second external terminal of the energy storage submodule. The first external terminal and the second external terminal are used to connect in series with the energy storage submodule.

[0010] The midpoint of the second switching arm is connected to the energy storage unit U via the interface inductor L. bk The positive electrode, the energy storage unit U bk The negative terminal is connected to the next node of the energy storage submodule.

[0011] Optionally, in another possible implementation of the first aspect, any of the above-mentioned energy-consuming submodules RSM j It has a first terminal and a second terminal, and includes a power-consuming resistor r and a bypass switch b;

[0012] The energy-consuming resistor r and the bypass switch b are connected in parallel between the first terminal and the second terminal, and the first terminal and the second terminal are used to connect in series with the energy-consuming submodule.

[0013] Secondly, embodiments of this application provide a control method for a modular energy storage and energy consumption co-operation hybrid DC energy consumption device, including: Step 1, acquiring the DC voltage U between the DC positive bus and the DC negative bus. dc And obtain the energy storage unit voltage U of each energy storage submodule. b,k State of charge (SOC) k and submodule capacitor voltage U C,k ; Obtain the temperature and bypass switch status of each energy-consuming submodule;

[0014] Step 2: Calculate the DC voltage deviation e u =U dc -U ref And according to U dc The operating modes of the energy storage start threshold U1, energy consumption fallback threshold U2, and discharge trigger threshold U3 determination device, wherein the U... ref This is a reference value for DC voltage.

[0015] Step 3: Based on the DC voltage deviation, generate the absorption power command P through proportional-integral adjustment. ∗ abs And limit its amplitude to meet the maximum absorption capacity and safety constraints allowed by the device;

[0016] Step 4: Calculate the upper limit P that energy storage can undertake based on energy storage-side constraints. ES,max The energy storage side constraints include the state of charge (SOC) constraints of the energy storage submodules, the capacitor voltage constraints of the submodules, the current constraints of the energy storage branches, and the charging and discharging power constraints of the energy storage; wherein, the SOC constraint is defined as the state of charge (SOC). min <SOC k <SOC max The capacitor voltage constraint of the submodule is U C,min <U C,k <U C,max The energy storage branch current constraint is that the energy storage branch current or the interface inductor current is less than a preset allowable current upper limit I. L,max The energy storage charging and discharging power constraint is that the charging and discharging power of the energy storage submodule is less than a preset allowable power limit P. ES,max And determine the energy storage power command P according to the principle of energy storage priority. ∗ ES With power consumption command P ∗ R :

[0017] Determine the energy storage power command P ∗ ES No more than P ES,max Determine the power consumption command P ∗ R For the remaining absorption demand; when the energy storage constraint condition or U is met dc When the energy consumption safety threshold U2 is exceeded, increase P. ∗ R In the power absorption command P ∗ abs The proportion in;

[0018] Step 5, according to P ∗ ES Determine the number n of energy storage sub-modules to be put into operation. on And select from n energy storage submodules:

[0019] For energy storage sub-modules that meet the energy storage constraint conditions, their use shall be prohibited or their use shall be reduced, and the number of energy-consuming sub-modules put into use shall be adjusted accordingly.

[0020] Under energy absorption conditions, in energy storage submodules that do not meet energy storage constraints, the state of charge (SOC) is calculated accordingly. k Sort the energy storage submodules in ascending order, and select n from the top-ranked submodules.on One energy storage sub-module was put into operation;

[0021] Under the backfeed operation, in energy storage submodules that do not meet the energy storage constraint conditions, according to the state of charge (SOC) k Sort the energy storage submodules in descending order, and select n from the top-ranked submodules. on One energy storage sub-module was put into operation;

[0022] Step 6: For the selected n on Each energy storage submodule controls its internal switching device T. 1k With T 2k The conduction state allows the energy storage submodule to switch between the on and off states, forming the required series output voltage U. out In the activated state, the voltage between the first external terminal of the energy storage submodule and the second external terminal of the energy storage submodule is located at the submodule capacitor voltage U. C,k Within the preset input voltage deviation range as a reference; in bypass mode, the terminal voltage between the first external terminal and the second external terminal does not exceed the preset bypass voltage threshold; using the inductor current of the interface inductor L as the control object, adjust its corresponding switching device T. 3k With T 4k The conduction method enables the energy storage unit U b,k Press P ∗ ES It performs charging absorption or discharging feedback, and converts the energy storage submodule capacitor voltage U C,k The constraints are within the preset range;

[0023] Step 7, according to P ∗ R Determine the number m of energy-consuming sub-modules to be put into operation. on The temperature data of each energy-consuming submodule is fused and processed to obtain the corresponding processing temperature. Based on the processing temperatures of each energy-consuming submodule, a temperature sequence is obtained by sorting the sequences from low to high, and the top m values ​​are selected from the sequence. on Each energy-consuming submodule is put into operation, and the temperature sequence excluding the first m... on Bypass and exit energy-consuming sub-modules other than the energy-consuming sub-module;

[0024] Step 8: During the operation of the energy-consuming sub-module, continuously monitor the processing temperature of the energy-consuming sub-module. When the processing temperature of any energy-consuming sub-module is greater than or equal to the preset temperature threshold, bypass the energy-consuming sub-module and select the energy-consuming sub-module that ranks higher in the temperature sequence from the energy-consuming sub-modules that have never been put into operation to replace it.

[0025] Step 9: Repeat steps 1 to 8 according to the preset control cycle, and update n in real time.on With m on ; when U dc When the system recovers to the preset allowable range and continues to meet the preset exit conditions, m will be gradually reduced. on Exit the energy-consuming submodule, then adjust n according to the preset requirements. on It enters standby or sustain mode, thus achieving a smooth switch from backup energy consumption to energy storage priority and then to standby.

[0026] In one possible implementation of the second aspect, step 2 described above, based on U dc The operating modes of the energy storage start-up threshold U1, energy consumption fallback threshold U2, and discharge trigger threshold U3 determination device include:

[0027] When U3≤U dc When ≤U1, the determination device enters standby mode;

[0028] When U1 < U dc When U2 < and the energy storage limitation condition is not met, the device is determined to enter the energy storage and absorption mode; the energy storage and absorption mode is determined according to the energy storage power command P. * ES Determine the number n of energy storage sub-modules to be put into operation. on And in energy storage sub-modules that do not meet the energy storage constraints, according to the state of charge (SOC) k Select n in ascending order on One energy storage submodule is put into operation, and the selected energy storage submodule is controlled to absorb the surplus power on the DC side. At the same time, the bypass switch b of the energy consumption submodule is controlled to be turned on, so that the energy consumption submodule is bypassed and de-energized.

[0029] When U dc >U2, or U1<U dc When <U2 and the energy storage limitation condition is met, the determination device enters the hybrid fallback mode; the hybrid fallback mode is to simultaneously activate the energy storage submodule and forcibly activate the energy consumption submodule as a fallback.

[0030] When U dc When <U3 and the energy storage constraint condition is not met, the device is determined to enter the energy storage feedback mode; the energy storage feedback mode is determined by the number n of energy storage sub-modules to be put into operation according to the energy storage feedback power command. on And in energy storage sub-modules that do not meet the energy storage constraints, according to the state of charge (SOC) k Select n in descending order on One energy storage submodule is put into operation, and the selected energy storage submodule is controlled to release energy to the DC side to assist in the recovery of DC voltage.

[0031] Optionally, in another possible implementation of the second aspect, the aforementioned energy storage constraints include: SOCk Reaching or exceeding SOC max SOC k Reaching or falling below SOC min U C,k Reaching or exceeding the preset voltage limit U C,max U C,k Reaching or falling below the preset lower voltage limit U C,min The current in the energy storage branch reaches or exceeds the preset allowable current limit I. L,max The charging and discharging power reaches or exceeds the preset allowable power limit P. ES,max .

[0032] Optionally, in another possible implementation of the second aspect, the temperature measurement data of each energy-consuming submodule in step 7 above are fused to obtain the corresponding processing temperature, specifically including:

[0033] Let T be the q temperature readings of the j-th energy-consuming submodule. j,1 ,…,T j,q Sort them from smallest to largest as T j,(1) ≤…≤T j,(q) After removing the maximum and minimum values, the average value is taken to obtain the processing temperature T. proc,j :

[0034] .

[0035] Optionally, in another possible implementation of the second aspect, the first m in step 7 above... on The energy-consuming submodule is activated as follows: the bypass switch b of the energy-consuming submodule is turned off, allowing the energy-consuming resistor r to be activated for energy consumption; the temperature sequence excluding the first m... on The bypass exit method for energy-consuming submodules other than the energy-consuming submodule is to control the bypass switch b of the energy-consuming submodule to be turned on so that it bypasses and exits.

[0036] Beneficial Effects: This application adopts a series-coordinated structure of energy storage submodules and energy dissipation submodules. During DC bus overvoltage, the energy storage submodules are prioritized to absorb surplus power and store it in the battery. Only when energy storage is limited or overvoltage is severe are the energy dissipation resistors activated as a fallback, thus recovering and utilizing the surplus power. This avoids the energy waste caused by direct heat dissipation in traditional solutions, significantly improving system economy. Simultaneously, the energy dissipation resistors are modularly configured in series, with each submodule connected to a parallel bypass switch and multiple temperature measurements. The processing temperature is obtained through extreme value removal and averaging. Based on temperature ranking, low-temperature modules are prioritized for activation, and rotation is performed when the rotation threshold is reached. This effectively distributes thermal stress, reduces the risk of single-point overheating, and improves the fault ride-through reliability and lifespan of the device. Furthermore, by setting multi-dimensional constraints such as state of charge (SOC), capacitor voltage, current, and power for the energy storage submodules, unconstrained modules are prioritized for activation, and selection is based on SOC levels during energy absorption or discharge conditions. This achieves SOC balance and maintains available capacity, ensuring the safe and efficient operation of the energy storage system. Attached Figure Description

[0037] To more clearly illustrate the technical solutions in the embodiments of this application, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0038] Figure 1 This is a schematic diagram of a scenario for a modular energy storage and energy consumption coordinating hybrid DC energy consumption device provided in one embodiment of this application;

[0039] Figure 2 This is a schematic diagram of the structure of a modular energy storage and energy consumption co-operation hybrid DC energy consumption device provided in an embodiment of this application;

[0040] Figure 3 This is a flowchart illustrating a control method for a modular energy storage and energy consumption coordinating hybrid DC energy consumption device according to an embodiment of this application;

[0041] Figure 4 This is a flowchart illustrating a control method for a modular energy storage and energy consumption coordinating hybrid DC energy consumption device according to another embodiment of this application;

[0042] Figure 5 This is a schematic flowchart of a control method for an energy storage submodule provided in an embodiment of this application;

[0043] Figure 6 This is a flowchart illustrating the control method for an energy-consuming submodule provided in an embodiment of this application. Detailed Implementation

[0044] In the following description, specific details such as particular system architectures and techniques are set forth for illustrative purposes and not for limitation, in order to provide a thorough understanding of the embodiments of this application. However, those skilled in the art will understand that this application may also be implemented in other embodiments without these specific details. In other instances, detailed descriptions of well-known systems, apparatuses, circuits, and methods have been omitted so as not to obscure the description of this application with unnecessary detail.

[0045] It should be understood that, when used in this application specification and the appended claims, the term "comprising" indicates the presence of the described features, integrals, steps, operations, elements and / or components, but does not exclude the presence or addition of one or more other features, integrals, steps, operations, elements, components and / or a collection thereof.

[0046] It should also be understood that the term “and / or” as used in this application specification and the appended claims means any combination of one or more of the associated listed items and all possible combinations, and includes such combinations.

[0047] As used in this application specification and the appended claims, the term "if" may be interpreted, depending on the context, as "when," "once," "in response to determination," or "in response to detection." Similarly, the phrase "if determined" or "if detected [the described condition or event]" may be interpreted, depending on the context, as meaning "once determined," "in response to determination," "once detected [the described condition or event]," or "in response to detection [the described condition or event]."

[0048] Furthermore, in the description of this application and the appended claims, the terms "first," "second," "third," etc., are used only to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0049] References to "one embodiment" or "some embodiments" as described in this specification mean that one or more embodiments of this application include a specific feature, structure, or characteristic described in connection with that embodiment. Therefore, the phrases "in one embodiment," "in some embodiments," "in other embodiments," "in still other embodiments," etc., appearing in different parts of this specification do not necessarily refer to the same embodiment, but rather mean "one or more, but not all, embodiments," unless otherwise specifically emphasized. The terms "comprising," "including," "having," and variations thereof mean "including but not limited to," unless otherwise specifically emphasized.

[0050] like Figure 1As shown, the modular energy storage and energy consumption co-operation hybrid DC energy consumption device of this application is connected between the DC positive bus and the DC negative bus of the DC system, and can be applied to the DC side of the offshore wind power transmission system via flexible DC. When the DC voltage rises due to an AC fault at the receiving end or a power imbalance on the DC side, the device suppresses the rapid rise of the DC bus voltage by absorbing the surplus power on the DC side; when the DC voltage is low and energy storage allows, the device can feed energy back to the DC side through the energy storage submodule to assist in the recovery of the DC voltage.

[0051] The following is a detailed description of a modular energy storage and energy consumption co-operation hybrid DC energy consumption device and its control method provided in this application.

[0052] Figure 2 A schematic diagram of a modular energy storage and energy consumption co-operation hybrid DC energy consumption device provided in an embodiment of this application is shown.

[0053] like Figure 2 As shown, this modular energy storage and energy consumption co-operation hybrid DC energy consumption device includes an energy storage sub-module string and a line inductor L. s And energy-consuming submodule strings;

[0054] The energy storage submodule string consists of n energy storage submodules connected in series, from ESM1 to ESM2. n , where n is a positive integer;

[0055] The energy-consuming submodule string consists of m energy-consuming submodules connected in series, from RSM1 to RSM2. m , where m is a positive integer;

[0056] Energy storage submodule string, line inductance L s The energy-consuming submodules are connected in series along the DC current channel to form a DC-side energy-absorbing branch. The upper end of the DC-side energy-absorbing branch is connected to the DC positive bus, and the lower end is connected to the DC negative bus.

[0057] It should be noted that the voltage across the energy storage submodule string is the output voltage U. out The voltage across the two ends of the energy-consuming submodule string is the energy-consuming voltage U. res The voltage between the positive and negative DC busbars is the DC voltage U. dc .

[0058] It should be noted that the line inductance L s This is used to limit the rate of change of current when the device is switched on or off, and to work with the control strategy to achieve smooth regulation of the energy-absorbing branch current. If the energy-absorbing branch current I... dc For the positive flow from the DC positive bus to the DC negative bus, the energy-absorbing branch satisfies the following approximate relationship in an average sense:

[0059]

[0060] Therefore, by adjusting U out with U res It can realize I dc And the adjustment of DC side absorption power.

[0061] Furthermore, in the embodiments of this application, any energy storage submodule ESM k It includes a first switch arm, a second switch arm, a submodule capacitor C, an interface inductor L, and a rechargeable battery energy storage unit U. bk ;

[0062] The first switch arm consists of a switching device T 1k With switching device T 2k The second switch arm is composed of a series connection and consists of a switching device T. 3k With switching device T 4k Composed of series connection;

[0063] The submodule capacitor C is connected across the upper and lower nodes of the energy storage submodule and is connected in parallel with the first switch arm and the second switch arm;

[0064] The midpoint of the first switch arm serves as the first external terminal of the energy storage submodule, and the lower node of the energy storage submodule serves as the second external terminal of the energy storage submodule. The first external terminal and the second external terminal are used to connect in series with the energy storage submodule.

[0065] The midpoint of the second switching arm is connected to the energy storage unit U via the interface inductor L. bk The positive electrode, the energy storage unit U bk The negative terminal is connected to the next node of the energy storage submodule.

[0066] It should be noted that the energy storage submodule ESM k It has both active and bypass states. This is controlled by T. 1k With T 2k In the ON state, the first external terminal presents a non-zero voltage or near-zero voltage relative to the second external terminal. In the OFF state, the energy storage submodule contributes a voltage U provided by the submodule capacitor C to the series link. C,k Thus participating in the formation of U out In bypass mode, the energy storage submodule's voltage contribution to the series link is approximately zero. This is achieved by considering the number of energy storage submodules, n, in operation. on And the selection of specific investment targets can achieve U out Reconfigurable adjustment.

[0067] It should be noted that the second switch arm and the interface inductor L form a bidirectional energy exchange channel between the battery storage unit and the submodule capacitor. Let the interface inductor current be i.L,k The equivalent voltage between the midpoint of the second switch arm and the lower node is v. 2,k The average model of the interface inductance is:

[0068]

[0069] By analyzing T 3k With T 4k Modulation is performed so that v 2,k Follow the set value, thereby achieving control over i L,k Closed-loop control to complete the control of U b,k The charging absorption or discharging feedback, and the submodule capacitor voltage U C,k The constraints are within a preset range.

[0070] For example, the preset range refers to the allowable operating range of the submodule capacitor voltage [U]. C,min U C,max ], where U C,min U is the lower limit of the capacitor voltage of the submodule. C,max This is the upper limit of the submodule capacitor voltage. It is based on the submodule capacitor's rated voltage U. C,ref Based on, U C,min 0.95U is a suitable value. C,ref U C,max It can be taken as 1.05U. C,ref . When U C,k Below U C,min or higher than U C,max When the voltage of the corresponding energy storage submodule exceeds the limit, the system will restrict the energy storage submodule from continuing to operate or reduce its charging and discharging power.

[0071] In this embodiment, the energy storage submodule is not simply a direct parallel connection of the energy storage unit to the two ends of the submodule capacitor. Instead, it comprises a first switch arm, a second switch arm, a submodule capacitor C, an interface inductor L, and a battery energy storage unit Ubk. The midpoint of the first switch arm and the lower node of the energy storage submodule serve as two external terminals of the energy storage submodule, used to enable or bypass the energy storage submodule in a series link. The midpoint of the second switch arm is connected to the energy storage unit Ubk via the interface inductor L, forming a bidirectional energy exchange channel between the energy storage unit and the submodule capacitor. Thus, on the one hand, the series output voltage of the energy storage submodule can be independently adjusted through the first switch arm; on the other hand, the charging and discharging current of the energy storage unit can be independently adjusted through the second switch arm and the interface inductor L, decoupling the series switching control of the energy storage submodule from the charging and discharging control of the energy storage unit. This structure reduces the current surge when the energy storage unit is directly connected to the DC submodule capacitor, improves the smoothness and controllability of the energy storage charging and discharging process, and facilitates coordinated control of DC voltage suppression, energy absorption, and energy feedback during fault ride-through.

[0072] Furthermore, in the embodiments of this application, any energy-consuming submodule RSM j It has a first terminal and a second terminal, and includes a power-consuming resistor r and a bypass switch b;

[0073] The energy-consuming resistor r and the bypass switch b are connected in parallel between the first terminal and the second terminal. The first terminal and the second terminal are used to connect in series with the energy-consuming submodule.

[0074] In this embodiment, the energy-consuming submodule switches between an energy-consuming input state and a bypass state by controlling the conduction state of the bypass switch b. In the energy-consuming input state, the bypass switch b is off, the resistor r bears the voltage across the module and dissipates energy; in the bypass state, the bypass switch b is on, the resistor r is bypassed, and the voltage drop across the module is approximately zero, thereby ensuring continuous and reconfigurable operation of the series link.

[0075] This application provides a modular energy storage and energy consumption coordinated hybrid DC energy dissipation device, including an energy storage submodule string and a line inductor L. s And the energy consumption submodule string; the energy storage submodule string includes n energy storage submodules ESM1 to ESM in series. n The energy-consuming submodule string includes m energy-consuming submodules connected in series, from RSM1 to RSM2. m Energy storage submodule string, line inductance L s The energy-consuming submodules are connected in series along the DC current path to form a DC-side energy-absorbing branch. The upper end of the DC-side energy-absorbing branch is connected to the DC positive bus, and the lower end is connected to the DC negative bus. This application replaces the traditional single energy-consuming resistor with a controllable energy-consuming submodule array, which works in conjunction with the energy storage submodule to achieve energy consumption and energy storage charging and discharging functions. It can better maintain the stability of the bus DC voltage and absorb surplus power during fault ride-through, and has good reliability and engineering adaptability.

[0076] Figure 3 The diagram shows a flow chart of a control method for a modular energy storage and energy consumption co-operation hybrid DC energy consumption device provided in an embodiment of this application.

[0077] like Figure 3 As shown, the control method for this modular energy storage and energy consumption coordinated hybrid DC energy consumption device includes:

[0078] Step 1: Collect the DC voltage U between the DC positive bus and the DC negative bus. dc And obtain the energy storage unit voltage U of each energy storage submodule. b,k State of charge (SOC) k and submodule capacitor voltage U C,k ; Obtain the temperature and bypass switch status of each energy-consuming submodule;

[0079] Step 2: Calculate the DC voltage deviation e u =U dc -U ref And according to U dc The operating modes of the energy storage start threshold U1, energy consumption fallback threshold U2, and discharge trigger threshold U3 determination device, wherein U ref This is a reference value for DC voltage.

[0080] Furthermore, in the embodiments of this application, such as Figure 4 As shown, in step 2 above, according to U dc The operating modes of the energy storage start-up threshold U1, energy consumption fallback threshold U2, and discharge trigger threshold U3 determination device include:

[0081] When U3≤U dc When ≤U1, the determination device enters standby mode;

[0082] When U1 < U dc When U2 is less than 2 and the energy storage limitation condition is not met, the device is determined to enter the energy storage absorption mode; the energy storage absorption mode is determined according to the energy storage power command P. * ES Determine the number n of energy storage sub-modules to be put into operation. on And in energy storage sub-modules that do not meet the energy storage constraints, according to the state of charge (SOC) k Select n in ascending order on One energy storage submodule is put into operation, and the selected energy storage submodule is controlled to absorb the surplus power on the DC side. At the same time, the bypass switch b of the energy consumption submodule is controlled to be turned on, so that the energy consumption submodule is bypassed and de-energized.

[0083] When U dc >U2, or U1<U dc When <U2 and the energy storage limitation condition is met, the device is determined to enter the hybrid fallback mode; the hybrid fallback mode is to simultaneously activate the energy storage submodule and force the energy consumption submodule to be activated as a fallback.

[0084] When U dc When U3 is less than 3 and the energy storage constraint condition is not met, the device is determined to enter the energy storage feedback mode; the energy storage feedback mode is determined by the number of energy storage sub-modules n to be put into operation according to the energy storage feedback power command. on And in energy storage sub-modules that do not meet the energy storage constraints, according to the state of charge (SOC) k Select n in descending order on One energy storage submodule is put into operation, and the selected energy storage submodule is controlled to release energy to the DC side to assist in the recovery of DC voltage.

[0085] It should be noted that the above-mentioned energy storage constraints include: SOC (State of Charge). k Reaching or exceeding SOCmax SOC k Reaching or falling below SOC min U C,k Reaching or exceeding the preset voltage limit U C,max U C,k Reaching or falling below the preset lower voltage limit U C,min The current in the energy storage branch reaches or exceeds the preset allowable current limit I. L,max The charging and discharging power reaches or exceeds the preset allowable power limit P. ES,max .

[0086] Step 3: Based on the DC voltage deviation, generate the absorption power command P through proportional-integral adjustment. ∗ abs And limit its amplitude to meet the maximum absorption capacity and safety constraints allowed by the device;

[0087] Step 4: Calculate the upper limit P that energy storage can undertake based on energy storage-side constraints. ES,max The energy storage side constraints include the state of charge constraints of the energy storage submodules, the capacitor voltage constraints of the submodules, the current constraints of the energy storage branches, and the energy storage charging and discharging power constraints; and the energy storage power command P is determined according to the energy storage priority principle. ∗ ES With power consumption command P ∗ R :

[0088] Determine the energy storage power command P ∗ ES No more than P ES,max Determine the power consumption command P ∗ R For the remaining absorption demand; when the energy storage constraint condition or U is met dc When the energy consumption safety threshold U2 is exceeded, increase P. ∗ R In the power absorption command P ∗ abs The proportion in;

[0089] Among them, the state of charge constraint is SOC. min <SOC k <SOC max The submodule capacitor voltage constraint is U C,min <U C,k <U C,max The energy storage branch current constraint is that the energy storage branch current or the interface inductor current is less than the preset allowable current upper limit I. L,max The energy storage charging and discharging power constraint is that the charging and discharging power of the energy storage submodule is less than the preset allowable power limit P. ES,max .

[0090] Step 5, according to P∗ ES Determine the number n of energy storage sub-modules to be put into operation. on And select from n energy storage submodules;

[0091] Specifically, for energy storage sub-modules that meet the energy storage constraint conditions, their use shall be prohibited or their use shall be reduced, and the number of energy-consuming sub-modules used shall be adjusted accordingly.

[0092] Under energy absorption conditions, in energy storage submodules that do not meet energy storage constraints, the state of charge (SOC) is calculated accordingly. k Sort the energy storage submodules in ascending order, and select n from the top-ranked submodules. on One energy storage sub-module was put into operation;

[0093] Under the backfeed operation, in energy storage submodules that do not meet the energy storage constraint conditions, according to the state of charge (SOC) k Sort the energy storage submodules in descending order, and select n from the top-ranked submodules. on One energy storage sub-module was put into operation;

[0094] In one embodiment, such as Figure 5 As shown, in the control of the energy storage submodule, the controller is based on P ∗ ES Calculate the number n of energy storage sub-modules put into operation. on And select from n energy storage submodules. Under energy absorption conditions, SOC is the preferred choice. k Lower-level energy storage submodules that have not triggered the upper limit constraint should be put into operation; under the back-out condition, SOC should be selected first. k Energy storage submodules with higher capacity that have not triggered the lower limit constraint will be put into operation. For energy storage submodules that do not meet the allowed operation constraints, operation will be prohibited or their power allocation command will be reduced, and the number of energy-consuming submodules put into operation will be adjusted accordingly to meet the DC side absorption demand, thereby achieving state of charge balance and maintaining available capacity.

[0095] Step 6: For the selected n on Each energy storage submodule controls its internal switching device T. 1k With T 2k The conduction state allows the energy storage submodule to switch between the on and off states, forming the required series output voltage U. out In the activated state, the voltage between the first external terminal of the energy storage submodule and the second external terminal of the energy storage submodule is located at the level of the submodule capacitor voltage U. C,k Within the preset input voltage deviation range as a reference; in bypass mode, the terminal voltage between the first external terminal and the second external terminal does not exceed the preset bypass voltage threshold; using the inductor current of the interface inductor L as the control object, adjust its corresponding switching device T. 3kWith T 4k The conduction method enables the energy storage unit U b,k Press P ∗ ES It performs charging absorption or discharging feedback, and converts the energy storage submodule capacitor voltage U C,k The constraints are within the preset range;

[0096] For example, let the terminal voltage between the first external terminal and the second external terminal of the k-th energy storage submodule be U. ESM,k The preset input voltage deviation range refers to U ESM,k Relative to the submodule capacitor voltage U C,k The allowable deviation range, i.e., satisfying |U ESM,k -U C,k |≤ΔU ins , where ΔU ins This is a preset input voltage deviation threshold. The rated voltage U of the submodule capacitor is used. C,ref Based on, ΔU ins It can be taken as 0.01U. C,ref In other words, when in operation, the voltage at the end of the energy storage submodule is allowed to be U C,k It fluctuates within a certain range nearby, without being required to be strictly equal to U. C,k .

[0097] Step 7, according to P ∗ R Determine the number m of energy-consuming sub-modules to be put into operation. on The temperature data of each energy-consuming submodule is fused and processed to obtain the corresponding processing temperature. Based on the processing temperatures of each energy-consuming submodule, a temperature sequence is obtained by sorting the sequences from low to high, and the top m values ​​are selected from the sequence. on Each energy-consuming submodule is put into operation, and the temperature sequence excluding the first m... on Bypass and exit energy-consuming sub-modules other than the energy-consuming sub-module;

[0098] In one embodiment, such as Figure 6 As shown, in the energy-consuming submodule control, the controller is based on P ∗ R Calculate the number m of energy-consuming sub-modules that are put into operation. on And perform input control on the selected energy-consuming submodule. For the selected m... on For each energy-consuming submodule, control its bypass switch b to turn off, so that the energy-consuming resistor r can be put into energy consumption; for the unselected energy-consuming submodule, control its bypass switch b to turn on so that the bypass is deactivated, so as to ensure the continuous and reconfigurable operation of the series link.

[0099] Furthermore, in this embodiment, the fusion processing of temperature measurement data from each energy-consuming submodule in step 7 above to obtain the corresponding processing temperature specifically includes:

[0100] Let T be the q temperature readings of the j-th energy-consuming submodule. j,1 ,…,T j,q Sort them from smallest to largest as T j,(1) ≤…≤T j,(q) After removing the maximum and minimum values, the average value is taken to obtain the processing temperature T. proc,j :

[0101] .

[0102] As one possible approach, temperature measurement points are set at the resistor body, heat sink, and housing to obtain optimal temperature data for the energy-consuming submodule.

[0103] Furthermore, in the embodiments of this application, the first m in step 7 above... on The energy-consuming submodule is activated as follows: the bypass switch b of the energy-consuming submodule is turned off, allowing the energy-consuming resistor r to be activated for energy consumption; in the temperature sequence, excluding the first m... on The bypass exit method for energy-consuming submodules other than the energy-consuming submodule is to control the bypass switch b of the energy-consuming submodule to be turned on so that it bypasses and exits.

[0104] Step 8: During the operation of the energy-consuming sub-module, continuously monitor the processing temperature of the energy-consuming sub-module. When the processing temperature of any energy-consuming sub-module is greater than or equal to the preset temperature threshold, bypass the energy-consuming sub-module and select the energy-consuming sub-module that ranks higher in the temperature sequence from the energy-consuming sub-modules that have never been put into operation to replace it.

[0105] Step 9: Repeat steps 1 to 8 according to the preset control cycle, and update n in real time. on With m on ; when U dc When the system recovers to the preset allowable range and continues to meet the preset exit conditions, m will be gradually reduced. on Exit the energy-consuming submodule, then adjust n according to the preset requirements. on It enters standby or sustain mode, thus achieving a smooth switch from backup energy consumption to energy storage priority and then to standby.

[0106] For example, the preset allowable range can refer to the DC voltage recovery range [U] rec,min U rec,max ]. Using the DC voltage reference value U ref Based on, U rec,min 0.95U is a suitable value. ref U rec,maxIt can be taken as 1.05 U. ref When the DC voltage U dc Satisfy U rec,min ≤U dc ≤U rec,max When the DC voltage recovers to the preset allowable range, it is determined that the DC voltage has returned to the preset allowable range.

[0107] For example, the preset exit conditions include at least one or a combination of the following conditions: DC voltage U dc It remains within the preset allowable range; power absorption command P ∗ abs Less than the preset power exit threshold P exit The energy-consuming sub-modules in operation are operating at temperatures below the preset temperature threshold T. swap The energy storage submodule did not trigger the energy storage limitation condition. The preset power exit threshold P exit The maximum absorption power P of the device can be taken as 1. abs,max 10%. When the above conditions are continuously met for the preset exit time t... exit When the preset exit condition is met, t is determined to be satisfied. exit 200ms is a suitable value.

[0108] For example, the preset requirements include at least one of the following: energy storage submodule state of charge maintenance requirements, submodule capacitor voltage maintenance requirements, and DC voltage stabilization requirements. The state of charge maintenance requirement refers to maintaining the energy storage submodule's state of charge (SOC). k Maintain at the target state of charge (SOC) mid Within the nearby preset range, where SOC mid It can be taken as (SOC) max +SOC min ) / 2, SOC k The allowable deviation range can be taken as SOC. mid ±5%; the submodule capacitor voltage maintenance requirement is to keep U C,k Maintain at [U C,min U C,max [Inside; the DC voltage stabilization requirement is to make U] dc Maintain at [U rec,min U rec,max [Inside.] The controller adjusts the number n of energy storage sub-modules put into operation according to the above preset requirements. on This puts the device into standby mode or maintenance mode.

[0109] This application provides a control method for a modular energy storage and energy consumption co-operation hybrid DC energy-consuming device. By real-time acquisition of DC voltage and the status of energy storage and energy consumption modules, the method automatically determines standby, energy absorption, hybrid fallback, or energy return modes based on voltage range and energy storage constraints. It dynamically allocates energy storage power commands and energy consumption power commands according to the principle of energy storage priority. This prioritizes utilizing surplus power from energy storage for energy recovery, while forcibly engaging energy consumption resistors as a fallback when energy storage is insufficient or overvoltage is severe, ensuring that the DC voltage remains controllable. Furthermore, based on the state of charge, capacitor voltage, current, and power constraints of the energy storage modules, the method selects modules for deployment and assigns them to either energy absorption or energy return modes. The system prioritizes optimal operating conditions, prohibiting or reducing the deployment of restricted modules while simultaneously adding energy-consuming resistors to fill power gaps, effectively achieving balanced state of charge and maintaining available capacity. Simultaneously, it performs extreme value removal and averaging fusion processing on multi-point temperature measurement data of energy-consuming modules, prioritizing the deployment of low-temperature modules based on the processed temperature, and performing rotation when the rotation threshold is reached and forced bypass when the temperature exceeds the limit, significantly reducing the risk of thermal stress concentration. Finally, through a periodic repetitive execution and smooth exit strategy, it prioritizes the exit of energy-consuming modules and then adjusts energy storage modules, achieving seamless switching from backup energy consumption to energy storage priority and then to standby, significantly improving the utilization efficiency of surplus power during DC fault ride-through, as well as the safety and long-term reliability of the device operation.

[0110] It should be understood that the sequence number of each step in the above embodiments does not imply the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of this application.

[0111] The above-described embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application, and should all be included within the protection scope of this application.

Claims

1. A modular energy storage and energy consumption co-operation hybrid DC energy consumption device, connected between the DC positive bus and the DC negative bus of a DC system, characterized in that, Including energy storage sub-module strings, line inductance L s And energy-consuming submodule strings; The energy storage submodule string includes n energy storage submodules connected in series, from ESM1 to ESM2. n , where n is a positive integer; The energy-consuming submodule string includes m energy-consuming submodules RSM1 to RSM1 connected in series. m , where m is a positive integer; The energy storage submodule string and the line inductance L s The energy-consuming submodules are connected in series along the DC current channel to form a DC-side energy-absorbing branch. The upper end of the DC-side energy-absorbing branch is connected to the DC positive bus, and the lower end is connected to the DC negative bus. Any Energy Storage Submodule (ESM) k It includes a first switch arm, a second switch arm, a submodule capacitor C, an interface inductor L, and a rechargeable battery energy storage unit U. bk ; The first switch arm consists of a switching device T 1k With switching device T 2k The second switch arm is composed of a series connection and consists of a switching device T. 3k With switching device T 4k Composed of series connection; The submodule capacitor C is connected across the upper and lower nodes of the energy storage submodule and is connected in parallel with the first switch arm and the second switch arm; The midpoint of the first switch arm serves as the first external terminal of the energy storage submodule, and the lower node of the energy storage submodule serves as the second external terminal of the energy storage submodule. The first external terminal and the second external terminal are used to connect in series with the energy storage submodule. The midpoint of the second switching arm is connected to the energy storage unit U via the interface inductor L. bk The positive electrode, the energy storage unit U bk The negative terminal is connected to the next node of the energy storage submodule.

2. The apparatus according to claim 1, characterized in that, Any energy-consuming submodule RSM j It has a first terminal and a second terminal, and includes a power-consuming resistor r and a bypass switch b; The energy-consuming resistor r and the bypass switch b are connected in parallel between the first terminal and the second terminal, and the first terminal and the second terminal are used to connect in series with the energy-consuming submodule.

3. A control method for a modular energy storage and energy consumption co-operation hybrid DC energy consumption device, applied to the device described in any one of claims 1-2, characterized in that, Includes the following steps: Step 1: Collect the DC voltage U between the DC positive bus and the DC negative bus. dc And obtain the energy storage unit voltage U of each energy storage submodule. b,k State of charge (SOC) k and submodule capacitor voltage U C,k ; Obtain the temperature and bypass switch status of each energy-consuming submodule; Step 2: Calculate the DC voltage deviation e u =U dc -U ref And according to U dc The operating modes of the energy storage start threshold U1, energy consumption fallback threshold U2, and discharge trigger threshold U3 determination device, wherein the U... ref This is a reference value for DC voltage. Step 3: Based on the DC voltage deviation, generate the absorption power command P through proportional-integral adjustment. ∗ abs And limit its amplitude to meet the maximum absorption capacity and safety constraints allowed by the device; Step 4: Calculate the upper limit P that energy storage can undertake based on energy storage-side constraints. ES,max The energy storage side constraints include the state of charge (SOC) constraints of the energy storage submodules, the capacitor voltage constraints of the submodules, the current constraints of the energy storage branches, and the charging and discharging power constraints of the energy storage; wherein, the SOC constraint is defined as the state of charge (SOC). min <SOC k <SOC max The capacitor voltage constraint of the submodule is U C,min <U C,k <U C,max The energy storage branch current constraint is that the energy storage branch current or the interface inductor current is less than a preset allowable current upper limit I. L,max The energy storage charging and discharging power constraint is that the charging and discharging power of the energy storage submodule is less than a preset allowable power limit P. ES,max And determine the energy storage power command P according to the principle of energy storage priority. ∗ ES With power consumption command P ∗ R : Determine the energy storage power command P ∗ ES No more than P ES,max Determine the power consumption command P ∗ R For the remaining absorption demand; when the energy storage constraint condition or U is met dc When the energy consumption safety threshold U2 is exceeded, increase P. ∗ R In the power absorption command P ∗ abs The proportion in; Step 5, according to P ∗ ES Determine the number n of energy storage sub-modules to be put into operation. on And select from n energy storage submodules: For energy storage sub-modules that meet the energy storage constraint conditions, their use shall be prohibited or their use shall be reduced, and the number of energy-consuming sub-modules put into use shall be adjusted accordingly. Under energy absorption conditions, in energy storage submodules that do not meet energy storage constraints, the state of charge (SOC) is calculated accordingly. k Sort the energy storage submodules in ascending order, and select n from the top-ranked submodules. on One energy storage sub-module was put into operation; Under the backfeed operation, in energy storage submodules that do not meet the energy storage constraint conditions, according to the state of charge (SOC) k Sort the energy storage submodules in descending order, and select n from the top-ranked submodules. on One energy storage sub-module was put into operation; Step 6: For the selected n on Each energy storage submodule controls its internal switching device T. 1k With T 2k The conduction state allows the energy storage submodule to switch between the on and off states, forming the required series output voltage U. out In the activated state, the voltage between the first external terminal of the energy storage submodule and the second external terminal of the energy storage submodule is located at the submodule capacitor voltage U. C,k Within the preset input voltage deviation range as a reference; in bypass mode, the terminal voltage between the first external terminal and the second external terminal does not exceed the preset bypass voltage threshold; using the inductor current of the interface inductor L as the control object, adjust its corresponding switching device T. 3k With T 4k The conduction method enables the energy storage unit U b,k Press P ∗ ES It performs charging absorption or discharging feedback, and converts the energy storage submodule capacitor voltage U C,k The constraints are within the preset range; Step 7, according to P ∗ R Determine the number m of energy-consuming sub-modules to be put into operation. on The temperature data of each energy-consuming submodule is fused and processed to obtain the corresponding processing temperature. Based on the processing temperatures of each energy-consuming submodule, a temperature sequence is obtained by sorting the sequences from low to high, and the top m values ​​are selected from the sequence. on Each energy-consuming submodule is put into operation, and the temperature sequence excluding the first m... on Bypass and exit energy-consuming sub-modules other than the energy-consuming sub-module; Step 8: During the operation of the energy-consuming sub-module, continuously monitor the processing temperature of the energy-consuming sub-module. When the processing temperature of any energy-consuming sub-module is greater than or equal to the preset temperature threshold, bypass the energy-consuming sub-module and select the energy-consuming sub-module that ranks higher in the temperature sequence from the energy-consuming sub-modules that have never been put into operation to replace it. Step 9: Repeat steps 1 to 8 according to the preset control cycle, and update n in real time. on With m on ; when U dc When the system recovers to the preset allowable range and continues to meet the preset exit conditions, m will be gradually reduced. on Exit the energy-consuming submodule, then adjust n according to the preset requirements. on It enters standby or sustain mode, thus achieving a smooth switch from backup energy consumption to energy storage priority and then to standby.

4. The method according to claim 3, characterized in that, Step 2, according to U dc The operating modes of the energy storage start-up threshold U1, energy consumption fallback threshold U2, and discharge trigger threshold U3 determination device include: When U3≤U dc When ≤U1, the determination device enters standby mode; When U1 < U dc When U2 < and the energy storage limitation condition is not met, the device is determined to enter the energy storage and absorption mode; the energy storage and absorption mode is determined according to the energy storage power command P. * ES Determine the number n of energy storage sub-modules to be put into operation. on And in energy storage sub-modules that do not meet the energy storage constraints, according to the state of charge (SOC) k Select n in ascending order on One energy storage submodule is put into operation, and the selected energy storage submodule is controlled to absorb the surplus power on the DC side. At the same time, the bypass switch b of the energy consumption submodule is controlled to be turned on, so that the energy consumption submodule is bypassed and de-energized. When U dc >U2, or U1<U dc When <U2 and the energy storage limitation condition is met, the determination device enters the hybrid fallback mode; the hybrid fallback mode is to simultaneously activate the energy storage submodule and forcibly activate the energy consumption submodule as a fallback. When U dc When <U3 and the energy storage constraint condition is not met, the device is determined to enter the energy storage feedback mode; the energy storage feedback mode is determined by the number n of energy storage sub-modules to be put into operation according to the energy storage feedback power command. on And in energy storage sub-modules that do not meet the energy storage constraints, according to the state of charge (SOC) k Select n in descending order on One energy storage submodule is put into operation, and the selected energy storage submodule is controlled to release energy to the DC side to assist in the recovery of DC voltage.

5. The method according to claim 4, characterized in that, The energy storage constraints include: SOC k Reaching or exceeding SOC max SOC k Reaching or falling below SOC min U C,k Reaching or exceeding the preset voltage limit U C,max U C,k Reaching or falling below the preset lower voltage limit U C,min The current in the energy storage branch reaches or exceeds the preset allowable current limit I. L,max The charging and discharging power reaches or exceeds the preset allowable power limit P. ES,max .

6. The method according to claim 5, characterized in that, Step 7, which involves fusing the temperature measurement data from each energy-consuming submodule to obtain the corresponding processing temperature, specifically includes: Let T be the q temperature readings of the j-th energy-consuming submodule. j,1 ,…,T j,q Sort them from smallest to largest as T j,(1) ≤…≤T j,(q) After removing the maximum and minimum values, the average value is taken to obtain the processing temperature T. proc,j : 。 7. The method according to claim 6, characterized in that, The first m in step 7 on The energy-consuming submodule is activated as follows: the bypass switch b of the energy-consuming submodule is turned off, allowing the energy-consuming resistor r to be activated for energy consumption; the temperature sequence excluding the first m... on The bypass exit method for energy-consuming submodules other than the energy-consuming submodule is to control the bypass switch b of the energy-consuming submodule to be turned on so that it bypasses and exits.

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