A module fault bypass control method and device for a high-voltage cascade energy storage system

Abstract

The application relates to a module fault bypass control method and device of a high-voltage cascade energy storage system. The method comprises the following steps: acquiring fault states of all sub-modules of the energy storage system, determining whether the system has a redundancy condition according to the number of sub-modules in each phase, the number of fault sub-modules in each phase and the minimum number of sub-modules in each phase; if the system has the redundancy condition, bypassing the fault sub-modules and increasing the modulation ratio of the non-fault sub-modules in each phase; if the system does not have the redundancy condition, locking the energy storage system to prevent hardware damage; after the sub-module fault is successfully bypassed, the controller stores a current bypass state word, so that after the controller is restarted or the controller is switched, it is still known that the fault module is in the bypass state; the controller sets two remote controls of 'unit bypass reset' and 'unit bypass clear', and after the energy storage converter is stopped and the fault sub-module is repaired, the two remote controls of 'unit bypass reset' and 'unit bypass clear' are driven to clear the bypass state word stored in the controller.

Description

Technical Field

[0001] This application relates to the field of energy storage system control technology, and in particular to a module fault bypass control method and device for a high-voltage cascaded energy storage system. Background Technology

[0002] The installed capacity of new energy sources will see a large-scale and rapid increase, but new energy power generation has serious randomness and volatility. Once large-scale new energy power generation is connected to the grid, the frequent power fluctuations it brings will lead to a dynamic imbalance between the active power output and the load of the power system, posing a severe challenge to the safety and stability of the power system.

[0003] Battery energy storage devices have fast response speed, strong short-term power throughput capacity, and bidirectional adjustment and precise tracking capabilities. They can play a key role in "peak shaving and valley filling" in new energy power plants, effectively control the power fluctuations of new energy power generation, and ensure the safe and stable operation of the power system.

[0004] In energy storage systems, different types of energy storage elements are connected through power conversion systems. Among them, chain topology has good application prospects in practical applications due to its modular structure, high voltage level and equivalent switching frequency.

[0005] High-voltage cascaded energy storage systems adopt a series structure between links, i.e., a series structure of sub-modules. If a certain margin is left in the number of links in the system, each link is equipped with a bypass switch or bypass power device. During normal operation of the system, the required number of links are put into operation according to control needs. When some links in the system fail, the faulty links are disconnected, and the system operates redundantly. This allows the system to maximize utilization while ensuring the safety of the devices and reduce the probability of new energy devices being disconnected from the grid due to energy storage system failures.

[0006] Therefore, online isolation of faulty links in the event of a single link failure and the realization of redundant control of energy storage systems are key technologies that must be achieved.

[0007] Prior art 1 discloses a redundant control system for a direct-connected energy storage converter based on port voltage state discrimination. It proposes a redundant control method for a direct-connected energy storage converter based on port voltage state discrimination. When a fault occurs in a certain link of the system, the faulty link is bypassed, and the voltage stability and balance of the AC output are maintained. Furthermore, there is no power deficit or short-term shutdown during the redundancy process, achieving seamless switching and reducing losses caused by system downtime due to partial link failures. Specifically, in step 2, the fault state of the faulty power module or battery pack is determined and located through autonomous discrimination and localization. Steps 3-5 determine the system's redundancy capability and rated power adjustment requirements, and adjust the system's rated power online according to the fault severity and system operating requirements, completing the system's redundant operation control and achieving seamless switching between healthy operating state and redundant state.

[0008] The shortcoming of the prior art 1 is that it uses the relationship between the expected output pulse modulation signal and the output voltage of the power module port to determine the fault, but does not latch the fault state of the sub-module. When the energy storage system is not unlocked and the module battery cluster has a fault, the module fault state cannot be obtained before unlocking. Bypassing after unlocking and putting the module into operation will cause unnecessary fluctuations.

[0009] The improvement of this invention compared to the prior art 1 lies in that, before unlocking, it integrates all fault information of the sub-modules, including the latched fault status, to avoid the faulty sub-modules being mistakenly activated, causing system fluctuations. In addition, it uses a statistical method for the number of faulty modules to determine the system redundancy capability, which is simpler and clearer than using the relationship between the module's rated voltage, current, and power to judge the system redundancy capability. The effect is that, in the application of high-voltage cascaded energy storage systems, through fault identification, module redundancy judgment, faulty module removal, and fault status latching, faulty sub-modules can be removed in a timely and accurate manner, avoiding unnecessary system fluctuations.

[0010] Prior art 2 discloses a medium-voltage direct-connected energy storage system and its online redundancy control method. The system includes a grid-connected switch G1, an AC pre-charge resistor R, an AC pre-charge bypass switch G2, an input three-phase reactor L, and cascaded sub-module units. The sub-module units include bypass modules, power modules, and battery clusters. When the system is connected to the grid, the pulse of the power modules is blocked, and the system is in grid-connected mode. When an AC side fault occurs, or when the redundancy operation capacity is exceeded, the system is in fault mode, all power module pulses are blocked, and G1 is disconnected. When a unit of the system fails, the system enters the redundancy operation mode. The proposed medium-voltage direct-connected energy storage system has high conversion efficiency and can meet the rapid development needs of large-scale energy storage technology. At the same time, by adding and removing online redundant modules of the medium-voltage direct-connected energy storage system, the reliability of the direct-connected energy storage system can be improved.

[0011] The shortcoming of the prior art 2 is that it does not latch the faulty submodule. After the controller restarts or switches, the faulty submodule may be re-engaged, resulting in unnecessary control fluctuations. After a module fails, all module pulses need to be blocked, the current needs to be cleared, the faulty module needs to be bypassed, and then the system switching process takes up to 10ms.

[0012] The improvement of this invention compared to the prior art 2 is that the state of the faulty submodule is latched to ensure that the submodule will not be mistakenly put into the control system when the fault is not cleared, thus preventing unnecessary fluctuations; after the submodule fault state is set, the system redundancy state can be determined in one control cycle (µs level). If the redundancy state is met, the bypass operation can be completed within several control cycles, locking the switching process. Summary of the Invention

[0013] Therefore, it is necessary to provide a module fault bypass control method and device for high-voltage cascaded energy storage systems that can effectively improve the utilization rate of high-voltage cascaded energy storage devices and avoid unexpected shutdowns due to factor module failures, in order to address the above-mentioned technical problems.

[0014] In a first aspect, this application provides a module fault bypass control method for a high-voltage cascaded energy storage system, comprising:

[0015] Step 1: Obtain the status of all sub-modules of the energy storage system;

[0016] Step 2: Once an anomaly is detected, the submodule is set to a fault state.

[0017] Step 3: Based on the fault status of all sub-modules obtained, determine whether the system has redundancy conditions;

[0018] Step 4: If the system has redundancy, bypass the faulty submodule; if the system does not have redundancy, lock out the energy storage system.

[0019] Preferably, in step 1, the state of the submodule includes the state of the battery cluster of the submodule and the state of each power electronic device of the submodule.

[0020] Preferably, in step 3, the method for determining whether the system has redundancy conditions is as follows:

[0021] Based on the fault information, determine whether the bypass switch V1 is faulty and whether the system has redundancy.

[0022] If the bypass switch fails, the system will not have redundancy.

[0023] If the bypass switch is not faulty, then based on the number of submodules N in each phase of the system settings, the minimum number of submodules N_L, and the number of faulty submodules M_j, determine whether the system has redundancy conditions:

[0024] If the number of submodules N in each of the three phases minus the number of faulty submodules M_j in the corresponding phase is greater than or equal to the minimum number of submodules N_L in that phase, then the system has redundancy.

[0025] If the number of submodules N in any of the three phases minus the number of faulty submodules M_j in the corresponding phase is less than the minimum number of submodules N_L in that phase, then the system does not have redundancy.

[0026] Preferably, in step 4, if the system has redundancy, the modulation ratio of the non-faulty submodules in the corresponding phase is increased while the faulty submodule is bypassed.

[0027] Preferably, the modulation ratio of the non-faulty submodule of the corresponding phase is increased from N_L / N to N_L / (N-M_j).

[0028] Preferably, in step 4, if the system has redundancy and the faulty submodule is successfully bypassed, the fault status of the faulty submodule is latched.

[0029] Preferably, latching the fault status of the fault submodule includes saving the bypass status word to the controller.

[0030] Preferably, the module fault bypass control method includes:

[0031] Step 5: The controller checks whether it has received remote control commands for "unit bypass reset" or "unit bypass clear".

[0032] Step 6: If the controller receives the remote control for "unit bypass reset" or "unit bypass clear", then clear the bypass status word stored in the controller.

[0033] Step 7: The energy storage controller restores the operating state of the submodule before the fault, including: removing the bypass to the faulty submodule; restoring the modulation ratio of the non-faulty submodule to N_L / N.

[0034] Secondly, this application provides a module fault bypass control device for a high-voltage cascaded energy storage system, characterized in that...

[0035] The module fault bypass control device includes a memory and a processor. The memory stores a computer program, and the processor executes the computer program in accordance with the module fault bypass control method for a high-voltage cascaded energy storage system according to any one of claims 1 to 8.

[0036] Preferably, the module fault bypass control device includes:

[0037] The submodule status acquisition module is used to acquire the status of all submodules in the energy storage system.

[0038] The logic judgment and execution module is used to determine whether the system has redundancy conditions. If the system has redundancy conditions, it will bypass the faulty sub-module; if the system does not have redundancy conditions, it will lock out the energy storage system.

[0039] The data storage module is used to store the fault status of the latching submodule;

[0040] The remote control command setting module is used to receive "unit bypass reset" and "unit bypass clear" remote commands to clear the fault status of the submodule.

[0041] The advantages of this invention compared to the prior art are as follows:

[0042] 1) Based on the calculated redundancy status, selective decisions are made on whether to continue operation, thereby maximizing the normal operation of the energy storage device and improving the device's availability while ensuring device safety;

[0043] 2) After bypassing the faulty submodule, the modulation ratio of each phase non-faulty submodule is increased to N / (N-M_j) times the original, thereby maintaining the stability of the output AC voltage of the energy storage system;

[0044] 3) Latch the fault status of the faulty submodule to ensure that after the controller is powered off and restarted or switched, the faulty module is still known to be in bypass state; before the faulty submodule is repaired, the faulty submodule is not mistakenly put into operation, thus ensuring the optimal working state of the device.

[0045] 4) The module fault bypass control device for implementing the module fault bypass control method of high-voltage cascaded energy storage system also has the above-mentioned beneficial effects.

[0046] It is understood that the beneficial effects that the above-mentioned module fault bypass control device for a high-voltage cascaded energy storage system can achieve can be referred to the beneficial effects of the module fault bypass control method for a high-voltage cascaded energy storage system as described in the first aspect, and will not be repeated here. Attached Figure Description

[0047] To more clearly illustrate the technical solutions in the embodiments of this application or the conventional technology, the drawings used in the description of the embodiments or the conventional technology 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.

[0048] Figure 1 This is a topology diagram of a high-voltage cascaded energy storage device;

[0049] Figure 2This is a flowchart illustrating a module fault bypass control method for a high-voltage cascaded energy storage system in one embodiment. Detailed Implementation

[0050] To facilitate understanding of this application, a more complete description will be provided below with reference to the accompanying drawings, which illustrate embodiments of the present application. However, the present application can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided so that the disclosure of this application will be thorough and complete.

[0051] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application.

[0052] Figure 1 This is a structural diagram of a high-voltage cascaded energy storage device. The three phase lines of the power grid are respectively connected to three-phase chain energy storage bridge arms. Each phase chain energy storage bridge arm has multiple power sub-modules. Each power sub-module includes a sub-power module device and a battery cluster module. An IGBT tube V1 is configured at the chain link port. If the tube is turned on, the chain link is bypassed.

[0053] In one embodiment, such as Figure 2 As shown, a module fault bypass control method for a high-voltage cascaded energy storage system is provided, including steps S110 to S180.

[0054] S110. Obtain the fault status of all sub-modules in the energy storage device.

[0055] The fault status of the submodule includes battery cluster fault, power device fault, power device trigger circuit fault, etc. Any fault or abnormality of any device will set the fault status of the submodule.

[0056] S120. Based on the fault status of all sub-modules obtained, determine whether there is a sub-module fault. If not, continue testing and the system will operate normally. If there is a sub-module fault, proceed to step S130.

[0057] S130. Based on the fault status of the submodule, determine whether the system has redundancy conditions.

[0058] Specifically, based on the fault information, it is determined whether the bypass switch V1 is faulty, and whether the system has redundancy.

[0059] If the bypass switch fails, the system will not have redundancy.

[0060] If the bypass switch is not faulty, then based on the acquired status of all submodules, count the number of faulty submodules M_j in each phase. Based on the system setpoint number of submodules N in each phase, the minimum number of submodules N_L in each phase, and the number of faulty submodules M_j, determine whether the system has redundancy.

[0061] If the number of three-phase submodules N minus the number of faulty submodules M_j in that phase is greater than or equal to the minimum number of submodules N_L in each phase, that is, the faulty submodule can continue to operate, then the system is determined to have redundancy conditions, and proceeds to S145.

[0062] If the number of phase submodules N minus the number of faulty phase submodules M_j is less than the minimum number of phase submodules N_L, and the system cannot maintain normal operation after the faulty submodule is removed, then the system is determined to lack redundancy and proceeds to S140.

[0063] S140. Immediately shut down the energy storage system to prevent the fault from spreading and causing instability in the external power system or equipment damage.

[0064] S145. Turn on the bypass IGBT V1 of all faulty submodules to isolate all faulty submodules.

[0065] S150. Increase the modulation ratio of each phase non-faulty submodule from N_L / N to N_L / (N-M_j) to maintain the stability of the output AC voltage of the energy storage system and ensure the continued operation of the device.

[0066] S155, The fault bypass status of the latching fault submodule includes: saving the bypass status word to the controller.

[0067] S160: The controller checks whether it has received two remote control commands: "Unit Bypass Reset" and "Unit Bypass Clear". If so, proceed to S170; otherwise, continue checking.

[0068] S170. Clear the bypass status word stored in the controller.

[0069] S180, the energy storage controller restores the operating state of the submodule before the fault and continues to monitor the fault status of all submodules.

[0070] Step S180 specifically includes: turning off the bypass IGBT tube of the submodule after the fault is turned off, so that the submodule is put into the system; sending modulation waves to each submodule according to control needs; canceling the original operation of the modulation ratio of each phase non-faulty submodule being N / (N-M_j) times the original, and restoring the original modulation ratio of the non-faulty submodule of that phase to N_L / N.

[0071] In one embodiment, a controller is provided, including a memory and a processor, the memory storing a computer program, the processor executing the computer program in accordance with the steps described in the above method embodiments.

[0072] In one embodiment, a module fault bypass control device for a high-voltage cascaded energy storage system is provided, comprising:

[0073] The submodule status acquisition module is used to acquire the fault status of all submodules in the energy storage system.

[0074] The logic judgment and execution module is used to determine whether the system has redundancy conditions. If the system has redundancy conditions, it will bypass the faulty sub-module; if the system does not have redundancy conditions, it will lock out the energy storage system.

[0075] The data storage module is used to latch the fault status of the submodule to prevent the faulty submodule from being put back into service.

[0076] The remote control command setting module is used to receive remote commands for "unit bypass reset" and "unit bypass clear" and promptly clear the fault status of the submodule.

[0077] Preferably, the remote control for "unit bypass reset" and "unit bypass clear" is given by the operator.

[0078] Those skilled in the art will understand that all or part of the processes in the methods of the above embodiments can be implemented by a computer program instructing related hardware. The computer program can be stored in a non-volatile computer memory, and when executed, it can include the processes of the embodiments of the methods described above.

[0079] The embodiments described above are merely one implementation method of this application, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims.

Claims

1. A module fault bypass control method for a high-voltage cascaded energy storage system, characterized in that, The module fault bypass control method includes: Step 1: Obtain the status of all sub-modules of the energy storage system; Step 2: Once an anomaly is detected, the submodule is set to a fault state. Step 3: Based on the fault status of all submodules obtained, determine whether the system has redundancy conditions; the method for determining whether the system has redundancy conditions in step 3 is as follows: Based on the fault information, determine whether the bypass switch V1 is faulty and whether the system has redundancy. If the bypass switch fails, the system will not have redundancy. If the bypass switch is not faulty, then based on the number of submodules N in each phase of the system settings, the minimum number of submodules N_L, and the number of faulty submodules M_j, determine whether the system has redundancy conditions: If the number of submodules N in each of the three phases minus the number of faulty submodules M_j in the corresponding phase is greater than or equal to the minimum number of submodules N_L in that phase, then the system has redundancy. If the number of submodules N in any of the three phases minus the number of faulty submodules M_j in the corresponding phase is less than the minimum number of submodules N_L in that phase, then the system does not have redundancy. Step 4: If the system has redundancy, bypass the faulty submodule; if the system does not have redundancy, lock out the energy storage system. In step 4, if the system has redundancy, while bypassing the faulty submodule, increase the modulation ratio of the non-faulty submodules of the corresponding phase. In step 4, if the system has redundancy and the faulty submodule is successfully bypassed, latch the fault state of the faulty submodule.

2. The module fault bypass control method for a high-voltage cascaded energy storage system according to claim 1, characterized in that, In step 1, the state of the submodule includes the state of the battery cluster of the submodule and the state of each power electronic device of the submodule.

3. The module fault bypass control method for a high-voltage cascaded energy storage system according to claim 1, characterized in that, Increase the modulation ratio of the non-faulty submodule of the corresponding phase from N_L / N to N_L / (N-M_j).

4. The module fault bypass control method for a high-voltage cascaded energy storage system according to claim 1, characterized in that, Latching the fault status of the fault submodule includes saving the bypass status word to the controller.

5. The module fault bypass control method for a high-voltage cascaded energy storage system according to claim 4, characterized in that, The module fault bypass control method includes: Step 5: The controller checks whether it has received a "unit bypass reset" or "unit bypass clear" remote control. Step 6: If the controller receives the "unit bypass reset" or "unit bypass clear" remote control, then clear the bypass status word stored in the controller. Step 7: The energy storage controller restores the operating state of the submodule before the fault, including: removing the bypass to the faulty submodule; restoring the modulation ratio of the non-faulty submodule to N_L / N.

6. A module fault bypass control device for a high-voltage cascaded energy storage system, characterized in that, The module fault bypass control device includes a memory and a processor. The memory stores a computer program, and the processor executes the computer program in accordance with the module fault bypass control method for a high-voltage cascaded energy storage system according to any one of claims 1 to 5.

7. The module fault bypass control device for a high-voltage cascaded energy storage system according to claim 6, characterized in that, The module fault bypass control device includes: The submodule status acquisition module is used to acquire the status of all submodules in the energy storage system. The logic judgment and execution module is used to determine whether the system has redundancy conditions. If the system has redundancy conditions, it will bypass the faulty sub-module; if the system does not have redundancy conditions, it will lock out the energy storage system. The data storage module is used to store the fault status of the latching submodule; The remote control command setting module is used to receive "unit bypass reset" and "unit bypass clear" remote commands to clear the fault status of the submodule.

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