A string type network construction type energy storage safety protection method
Patent Information
- Application Number
- CN202611183050.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-08-05
- Publication Date
- 2026-10-16
AI Technical Summary
[0003]本发明的目的在于：提出一种组串式构网型储能安全防护方法，以解决上述背景技术中提出的难以有效对组串式构网型储能系统进行安全防护问题
1、本发明首先依据储能系统与目标负载的不同功率对当前时间节点时储能系统的电网接入状态进行分析，从而判断得到储能系统的电网接入状态为并网状态或离网状态，本发明实现对储能系统并网状态的有效判断；
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Figure CN122931910A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of energy storage safety protection technology, specifically a string-grid type energy storage safety protection method. Background Technology
[0002] With the accelerated global energy transition, the installed capacity of new energy power generation such as wind power and photovoltaic power generation continues to grow rapidly. The power system is gradually showing the "double high" characteristics of high proportion of new energy and high proportion of power electronic equipment. The proportion of traditional synchronous generator sets continues to decline, resulting in a decrease in system inertia level and a weakening of voltage and frequency active support capabilities. While string-type grid-connected energy storage systems can currently simulate the operating characteristics of synchronous generators to support the power system, the large number of energy storage units within these systems makes it difficult to maintain consistency during power supply. When adjustments to the system are needed, it's impossible to effectively adapt to different energy storage units. Furthermore, when the system supplies power independently, it's difficult to predict the duration of power supply. Consequently, effective safety protection for string-type grid-connected energy storage systems is currently challenging. Therefore, this invention proposes a safety protection method for string-type grid-based energy storage. Summary of the Invention
[0003] The purpose of this invention is to propose a safety protection method for string-type grid-based energy storage systems, in order to solve the problem of difficulty in effectively protecting string-type grid-based energy storage systems mentioned in the background art.
[0004] To achieve the above objectives, the present invention adopts the following technical solution: A safety protection method for string-type grid-based energy storage includes the following steps: Step S1: Analyze the grid connection status of the energy storage system at the current time node to determine whether the grid connection status of the energy storage system is grid-connected or off-grid. Step S2: When the grid connection status of the energy storage system is grid-connected, analyze the different power adjustment amounts of the energy storage system to obtain the active power adjustment amount and reactive power adjustment amount of the energy storage system. Step S3: Analyze different energy storage units based on active power adjustment and reactive power adjustment to obtain the actual active power adjustment and actual reactive power adjustment of different energy storage units. Step S4: When the grid connection status of the energy storage system is off-grid status, analyze the load status of the energy storage system at the current time node to determine whether the load status of the energy storage system is full load or not full load. Step S5: Based on the active power of the target load at different time points, predict the remaining working time of the energy storage system under the condition of not being fully loaded, and obtain the remaining energy supply time of the energy storage system.
[0005] Furthermore, the analysis process in step S1 includes the following sub-steps: Step S101: Obtain the real-time electrical data of the energy storage system and the load electrical data of the target load at the current time point; Among them, the real-time electrical data are the real-time three-phase voltage, real-time three-phase current and real-time phase difference of the energy storage system, and the load electrical data are the load three-phase voltage, load three-phase current and load phase difference of the target load. Step S102: Multiply the fixed value by the real-time three-phase voltage to obtain the real-time line voltage of the energy storage system, and multiply the fixed value by the real-time three-phase current to obtain the real-time line current of the energy storage system. Step S103: Multiply the fixed value by the cosine of the real-time phase difference, the real-time line voltage, and the real-time line current respectively to obtain the real-time active power of the energy storage system at the current time node. The fixed value is multiplied by the sine value of the real-time phase difference, the real-time line voltage, and the real-time line current to obtain the real-time reactive power of the energy storage system at the current time point. Step S104: Repeat steps S102 and S103 to calculate the active power and reactive power of the target load. Step S105: Compare the real-time active power of the energy storage system with the load active power of the target load at the current time node, and compare the real-time reactive power of the energy storage system with the load reactive power of the target load at the current time node. If the real-time active power of the energy storage system at the current time node is greater than or equal to the load active power of the target load, and the real-time reactive power of the energy storage system at the current time node is greater than or equal to the load reactive power of the target load, then the grid connection status of the energy storage system at the current time node is recorded as the off-grid status. If the real-time active power of the energy storage system is less than the load active power of the target load at the current time point, or if the real-time reactive power of the energy storage system is less than the load reactive power of the target load at the current time point, then the grid connection status of the energy storage system at the current time point is recorded as the grid-connected status.
[0006] Furthermore, the analysis process in step S2 includes the following sub-steps: Step S201: Obtain the rated frequency, real-time frequency, rated voltage and real-time voltage at the grid connection point in the power grid, and compare the real-time frequency at the grid connection point with the rated frequency and the real-time voltage at the grid connection point with the rated voltage. If the real-time frequency at the grid connection point is not equal to the rated frequency, but the real-time voltage is equal to the rated voltage, then proceed to step S202. If the real-time frequency at the grid connection point is equal to the rated frequency, but the real-time voltage is not equal to the rated voltage, then proceed to step S203. If the real-time frequency at the grid connection point is equal to the rated frequency and the real-time voltage is equal to the rated voltage, then no operation is performed. If the real-time frequency at the grid connection point is not equal to the rated frequency, and the real-time voltage is not equal to the rated voltage, then the active power adjustment and reactive power adjustment of the energy storage system can be obtained through analysis. Step S202: Analyze the droop coefficient of the energy storage converter based on the real-time frequency and the rated frequency to obtain the active power adjustment of the energy storage system. Step S203: Analyze the droop coefficient of different energy storage converters based on the real-time voltage and rated voltage, and obtain the reactive power adjustment of the energy storage system.
[0007] Furthermore, the analysis process in step S202 includes the following sub-steps: Step S2021: Subtract the rated frequency from the real-time frequency to obtain the frequency deviation at the grid connection point; Step S2022: Obtain the frequency deviation threshold and the rated output power of the energy storage converter at the grid connection point, divide the frequency deviation threshold by the rated output power to obtain the droop coefficient of different energy storage converters, and sum the reciprocals of the different droop coefficients to obtain the frequency power factor of the energy storage system. Step S2023: Multiply the frequency deviation by the frequency power factor and take the absolute value to obtain the active power adjustment of the energy storage system.
[0008] Furthermore, the analysis process in step S203 includes the following sub-steps: Step S2031: Subtract the rated voltage from the real-time voltage to obtain the voltage deviation at the grid connection point; Step S2032: Obtain the voltage deviation threshold and the rated reactive power of the energy storage converter at the grid connection point, divide the voltage deviation threshold by the rated reactive power to obtain the droop coefficient of different energy storage converters, and sum the reciprocals of the different droop coefficients to obtain the voltage power factor of the energy storage system. Step S2033: Multiply the voltage deviation by the voltage power factor and take the absolute value to obtain the reactive power adjustment of the energy storage system.
[0009] Furthermore, the analysis process in step S3 includes the following sub-steps: Step S301: Obtain the rated capacity and real-time power consumption of different energy storage units at the current time node. Subtract the real-time power consumption from the rated capacity and divide by the rated capacity to obtain the remaining power ratio of different energy storage units at the current time node. Step S302: Divide the remaining power of the energy storage unit into a first power range, a second power range, and a third power range. Step S303: Energy storage units whose remaining power percentage falls within the first power range are designated as Level 1 energy storage units, energy storage units whose remaining power percentage falls within the second power range are designated as Level 2 energy storage units, and energy storage units whose remaining power percentage falls within the third power range are designated as Level 3 energy storage units.
[0010] Furthermore, the values within the first power range are all greater than the values within the second power range, and the values within the second power range are all greater than the values within the third power range.
[0011] Furthermore, the analysis process in step S3 also includes the following sub-steps: Step S304: Count the number of all energy storage units in the energy storage system and record it as the total number of energy storage units. Divide the active power adjustment by the total number of energy storage units to obtain the ideal active power adjustment of a single energy storage unit. Divide the reactive power adjustment by the total number of energy storage units to obtain the ideal reactive power adjustment of a single energy storage unit. Step S305: Divide the ideal active power adjustment of the three-level energy storage unit by two to obtain the actual active power adjustment of the corresponding energy storage unit, and divide the ideal active power adjustment of the three-level energy storage unit by two to obtain the actual reactive power adjustment of the corresponding energy storage unit. Step S306: Take the ideal active power adjustment of the secondary energy storage unit as the actual active power adjustment, and take the ideal reactive power adjustment of the secondary energy storage unit as the actual reactive power adjustment. Step S307: Add the actual active power adjustment of the secondary energy storage unit to the ideal active power adjustment of the primary energy storage unit to obtain the actual active power adjustment of the primary energy storage unit. The actual reactive power adjustment of the primary energy storage unit is obtained by summing the actual active power adjustment of the secondary energy storage unit with the ideal active power adjustment of the primary energy storage unit.
[0012] Furthermore, the analysis process in step S4 includes the following sub-steps: Step S401: Obtain the active power and reactive power of the target load at the current time point. Then, the square of the sum of the square of the active power of the load and the square of the square of the reactive power of the load is taken to obtain the apparent power of the target load at the current time point. Step S402: Obtain the rated output power and rated apparent power of different energy storage converters, sum the different rated output powers to obtain the limit output power of the energy storage system, and sum the different rated apparent powers to obtain the limit apparent power of the energy storage system. Step S403: Compare the apparent power of the target load at the current time node with the limit apparent power of the energy storage system, and compare the active power of the target load at the current time node with the limit output power of the energy storage system. If the apparent power of the target load at the current time point is greater than or equal to the limit apparent power of the energy storage system, or the active power of the target load at the current time point is greater than or equal to the limit output power of the energy storage system, then the load state of the energy storage system at the current time point is recorded as full load state. If the apparent power of the target load at the current time point is less than the limit apparent power of the energy storage system, and the active power of the target load at the current time point is less than the limit output power of the energy storage system, then the load state of the energy storage system at the current time point is recorded as not fully loaded.
[0013] Furthermore, the prediction process in step S5 includes the following sub-steps: Step S501: Obtain the active power of the target load at different time nodes, and subtract the active power of the target load at the previous time node from the active power of the target load at the current time node to obtain the change in the active power of the target load at the current time node. By analogy, the change in active power of the target load at different time points can be calculated; Step S502: Iterate through and compare the active power change of the target load at different time points to obtain the maximum value of the active power change. Divide the maximum value of the active power change by a fixed time interval to obtain the predicted active power change rate of the target load. Step S503: Subtract the load active power from the limit output power to obtain the remaining output power of the energy storage system at the current time node, and divide the remaining output power by the predicted active power change rate to obtain the remaining energy supply duration of the energy storage system.
[0014] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are: 1. This invention first analyzes the grid connection status of the energy storage system at the current time node based on the different power of the energy storage system and the target load, thereby determining whether the grid connection status of the energy storage system is grid-connected or off-grid. This invention achieves effective judgment of the grid connection status of the energy storage system. 2. This invention further analyzes the different power adjustment amounts of the energy storage system under grid-connected conditions, thereby obtaining the active power adjustment amount and reactive power adjustment amount of the energy storage system. Then, based on the active power adjustment amount and reactive power adjustment amount, different energy storage units are analyzed to obtain the actual active power adjustment amount and actual reactive power adjustment amount of different energy storage units. At the same time, the load status of the energy storage system under off-grid conditions is analyzed to determine whether the load status of the energy storage system is full-load or not. Finally, based on the active power of the target load at different time points, the remaining working time of the energy storage system under the not-full-load condition is predicted to obtain the remaining power supply time of the energy storage system. This invention achieves effective safety protection for string-type grid-connected energy storage systems. Attached Figure Description
[0015] To facilitate understanding by those skilled in the art, the present invention will be further described below with reference to the accompanying drawings.
[0016] Figure 1 This is a flowchart of the method of the present invention; Figure 2 This is a schematic diagram of the energy storage unit and energy storage module in this invention; Figure 3 This is a schematic diagram of a scenario for the present invention; Figure 4 This is a flowchart illustrating the logic of the present invention. Figure 5 This is a schematic diagram of the electronic device in this invention. Detailed Implementation
[0017] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.
[0018] Example 1, please refer to Figures 1-4 As shown, the technical solution provided by this invention is: a safety protection method for string-type grid-connected energy storage. This method first analyzes the grid connection status of the energy storage system, then analyzes the adjustment of active and reactive power of different energy storage units under grid-connected status, or predicts the remaining operating time of the energy storage system under off-grid status. The specific method is as follows: In this embodiment, please refer to Figure 2 As shown, multiple batteries are connected in series to form an energy storage unit, and each energy storage unit is connected in series with a single energy storage inverter to form an energy storage module; In the specific implementation process, multiple energy storage modules are connected in parallel to form an energy storage system. Then, the energy storage system is connected to the power grid and the target load. The location where the energy storage system is connected to the power grid and the target load is recorded as the grid connection point. Step S1: Analyze the grid connection status of the energy storage system at the current time node to determine whether the grid connection status of the energy storage system is grid-connected or off-grid. In this embodiment, the analysis process in step S1 includes the following sub-steps: Step S101: Obtain the real-time electrical data of the energy storage system and the load electrical data of the target load at the current time point; Among them, the real-time electrical data are the real-time three-phase voltage, real-time three-phase current and real-time phase difference of the energy storage system, and the load electrical data are the load three-phase voltage, load three-phase current and load phase difference of the target load. Step S102: Multiply the fixed value by the real-time three-phase voltage to obtain the real-time line voltage of the energy storage system, and multiply the fixed value by the real-time three-phase current to obtain the real-time line current of the energy storage system. Step S103: Multiply the fixed value by the cosine of the real-time phase difference, the real-time line voltage, and the real-time line current respectively to obtain the real-time active power of the energy storage system at the current time node. The fixed value is multiplied by the sine value of the real-time phase difference, the real-time line voltage, and the real-time line current to obtain the real-time reactive power of the energy storage system at the current time point. In this embodiment, the fixed values in steps S102 and S103 are both √3. It should be explained that the fixed values in both places are a rated part of the existing active power and existing reactive power calculation formulas. Step S104: Repeat steps S102 and S103 to calculate the active power and reactive power of the target load. Step S105: Compare the real-time active power of the energy storage system with the load active power of the target load at the current time node, and compare the real-time reactive power of the energy storage system with the load reactive power of the target load at the current time node. If the real-time active power of the energy storage system at the current time node is greater than or equal to the load active power of the target load, and the real-time reactive power of the energy storage system at the current time node is greater than or equal to the load reactive power of the target load, then the grid connection status of the energy storage system at the current time node is recorded as the off-grid status. If the real-time active power of the energy storage system is less than the load active power of the target load at the current time point, or if the real-time reactive power of the energy storage system is less than the load reactive power of the target load at the current time point, then the grid connection status of the energy storage system at the current time point is recorded as the grid-connected status. It should be explained that string-type grid-connected energy storage systems can simulate the characteristics of synchronous generators, and can independently establish voltage and frequency without relying on the external power grid. They can be used to assist the grid in supplying power to the load and to supply power to the load independently. In this embodiment, when the real-time active power is greater than or equal to the load active power and the real-time reactive power is greater than or equal to the load reactive power, it indicates that the power supply of the energy storage system is used for transmission losses and the power consumption of the target load. At this time, the energy storage system is in an off-grid state. When the real-time active power is less than the load active power or the real-time reactive power is less than the load reactive power, the power supply of the energy storage system is insufficient to support the power consumption of the target load. This indicates that the energy storage system is in a grid-connected state and is used to assist the grid in supplying power to the target load.
[0019] Step S2: When the grid connection status of the energy storage system is grid-connected, analyze the different power adjustment amounts of the energy storage system to obtain the active power adjustment amount and reactive power adjustment amount of the energy storage system. In this embodiment, the analysis process in step S2 includes the following sub-steps: Step S201: Obtain the rated frequency, real-time frequency, rated voltage and real-time voltage at the grid connection point in the power grid, and compare the real-time frequency at the grid connection point with the rated frequency and the real-time voltage at the grid connection point with the rated voltage. If the real-time frequency at the grid connection point is not equal to the rated frequency, but the real-time voltage is equal to the rated voltage, then proceed to step S202. If the real-time frequency at the grid connection point is equal to the rated frequency, but the real-time voltage is not equal to the rated voltage, then proceed to step S203. If the real-time frequency at the grid connection point is equal to the rated frequency and the real-time voltage is equal to the rated voltage, then no operation is performed. If the real-time frequency at the grid connection point is not equal to the rated frequency, and the real-time voltage is not equal to the rated voltage, then the active power adjustment and reactive power adjustment of the energy storage system can be obtained through analysis. In this embodiment, the rated frequency and rated voltage of the power grid can be obtained from the power specification parameters of the power grid. The analysis process of the active power adjustment and reactive power adjustment is the same as that in steps S202 and S203, and will not be repeated here. Step S202: Analyze the droop coefficient of the energy storage converter based on the real-time frequency and the rated frequency to obtain the active power adjustment of the energy storage system. In this embodiment, the analysis process in step S202 includes the following sub-steps: Step S2021: Subtract the rated frequency from the real-time frequency to obtain the frequency deviation at the grid connection point; Step S2022: Obtain the frequency deviation threshold and the rated output power of the energy storage converter at the grid connection point, divide the frequency deviation threshold by the rated output power to obtain the droop coefficient of different energy storage converters, and sum the reciprocals of the different droop coefficients to obtain the frequency power factor of the energy storage system. In this embodiment, the frequency deviation threshold is the maximum allowable frequency deviation at the grid connection point during grid operation, and the frequency deviation threshold is a fixed preset value; Step S2023: Multiply the frequency deviation by the frequency power factor and take the absolute value to obtain the active power adjustment of the energy storage system. Step S203: Analyze the droop coefficient of different energy storage converters based on the real-time voltage and rated voltage, and obtain the reactive power adjustment of the energy storage system. In this embodiment, the analysis process in step S203 includes the following sub-steps: Step S2031: Subtract the rated voltage from the real-time voltage to obtain the voltage deviation at the grid connection point; Step S2032: Obtain the voltage deviation threshold and the rated reactive power of the energy storage converter at the grid connection point, divide the voltage deviation threshold by the rated reactive power to obtain the droop coefficient of different energy storage converters, and sum the reciprocals of the different droop coefficients to obtain the voltage power factor of the energy storage system. In this embodiment, the voltage deviation threshold is the maximum allowable voltage deviation at the grid connection point during grid operation, and the voltage deviation threshold is a fixed preset value; Step S2033: Multiply the voltage deviation by the voltage power factor and take the absolute value to obtain the reactive power adjustment of the energy storage system.
[0020] Step S3: Analyze different energy storage units based on active power adjustment and reactive power adjustment to obtain the actual active power adjustment and actual reactive power adjustment of different energy storage units. In this embodiment, the analysis process in step S3 includes the following sub-steps: Step S301: Obtain the rated capacity and real-time power consumption of different energy storage units at the current time node. Subtract the real-time power consumption from the rated capacity and divide by the rated capacity to obtain the remaining power ratio of different energy storage units at the current time node. Step S302: Divide the remaining power of the energy storage unit into a first power range, a second power range, and a third power range. Among them, the values in the first power range are all greater than the values in the second power range, and the values in the second power range are all greater than the values in the third power range. For example, the first power range is (66%, 100%), the second power range is (33%, 66%), and the third power range is [0%, 33%). It should be explained that parentheses indicate an open range, that is, the range does not include the endpoint value, and square brackets indicate a closed range, that is, the range includes the endpoint value. Step S303: Energy storage units whose remaining power percentage belongs to the first power range are recorded as first-level energy storage units, energy storage units whose remaining power percentage belongs to the second power range are recorded as second-level energy storage units, and energy storage units whose remaining power percentage belongs to the third power range are recorded as third-level energy storage units. Step S304: Count the number of all energy storage units in the energy storage system and record it as the total number of energy storage units. Divide the active power adjustment by the total number of energy storage units to obtain the ideal active power adjustment of a single energy storage unit. Divide the reactive power adjustment by the total number of energy storage units to obtain the ideal reactive power adjustment of a single energy storage unit. Step S305: Divide the ideal active power adjustment of the three-level energy storage unit by two to obtain the actual active power adjustment of the corresponding energy storage unit, and divide the ideal active power adjustment of the three-level energy storage unit by two to obtain the actual reactive power adjustment of the corresponding energy storage unit. Step S306: Take the ideal active power adjustment of the secondary energy storage unit as the actual active power adjustment, and take the ideal reactive power adjustment of the secondary energy storage unit as the actual reactive power adjustment. Step S307: Add the actual active power adjustment of the secondary energy storage unit to the ideal active power adjustment of the primary energy storage unit to obtain the actual active power adjustment of the primary energy storage unit. The actual active power adjustment of the secondary energy storage unit is summed with the ideal active power adjustment of the primary energy storage unit to obtain the actual reactive power adjustment of the primary energy storage unit. In the specific implementation process, the energy storage converter adjusts the active and reactive power of different energy storage units based on the actual active power adjustment and the actual reactive power adjustment.
[0021] Step S4: When the grid connection status of the energy storage system is off-grid status, analyze the load status of the energy storage system at the current time node to determine whether the load status of the energy storage system is full load or not full load. In this embodiment, the analysis process in step S4 includes the following sub-steps: Step S401: Obtain the active power and reactive power of the target load at the current time point. Then, the square of the sum of the square of the active power of the load and the square of the square of the reactive power of the load is taken to obtain the apparent power of the target load at the current time point. Step S402: Obtain the rated output power and rated apparent power of different energy storage converters, sum the different rated output powers to obtain the limit output power of the energy storage system, and sum the different rated apparent powers to obtain the limit apparent power of the energy storage system. Step S403: Compare the apparent power of the target load at the current time node with the limit apparent power of the energy storage system, and compare the active power of the target load at the current time node with the limit output power of the energy storage system. If the apparent power of the target load at the current time point is greater than or equal to the limit apparent power of the energy storage system, or the active power of the target load at the current time point is greater than or equal to the limit output power of the energy storage system, then the load state of the energy storage system at the current time point is recorded as full load state. If the apparent power of the target load at the current time point is less than the limit apparent power of the energy storage system, and the active power of the target load at the current time point is less than the limit output power of the energy storage system, then the load state of the energy storage system at the current time point is recorded as not fully loaded. In the specific implementation process, the rated apparent power can be obtained from the electrical specifications of the energy storage converter. When the load status of the energy storage system is at full load, an early warning will be issued immediately and relevant personnel will be reminded to carry out power dispatch.
[0022] Step S5: Based on the active power of the target load at different time points, predict the remaining working time of the energy storage system under the condition of not being fully loaded, and obtain the remaining energy supply time of the energy storage system. In this embodiment, the prediction process in step S5 includes the following sub-steps: Step S501: Obtain the active power of the target load at different time nodes, and subtract the active power of the target load at the previous time node from the active power of the target load at the current time node to obtain the change in the active power of the target load at the current time node. By analogy, the change in active power of the target load at different time points can be calculated; Step S502: Iterate through and compare the active power change of the target load at different time points to obtain the maximum value of the active power change. Divide the maximum value of the active power change by a fixed time interval to obtain the predicted active power change rate of the target load. Step S503: Subtract the load active power from the limit output power to obtain the remaining output power of the energy storage system at the current time node, and divide the remaining output power by the predicted active power change rate to obtain the remaining energy supply duration of the energy storage system. During the implementation process, relevant personnel need to charge the energy storage system or add energy storage units within the remaining power supply time.
[0023] Example 2: This embodiment of the invention also provides an electronic device for operating the aforementioned string-grid energy storage safety protection method; see [link to previous embodiment]. Figure 5 The schematic diagram of an electronic device provided by the embodiment of the present invention shown above includes a memory and a processor. The memory is used to store one or more computer instructions, which are executed by the processor to realize the above-mentioned string-grid type energy storage safety protection method. Furthermore, Figure 5 The electronic device shown also includes a communication bus and a communication interface, with the processor, communication interface and memory connected via the communication bus; The memory may include high-speed random access memory (RAM) and may also include non-volatile memory, such as at least one disk storage device. Communication between this system network element and at least one other network element is achieved through at least one communication interface (which can be wired or wireless), such as the Internet, wide area network, local area network, metropolitan area network, etc. The communication bus can be an ISA bus, PCI bus, or EISA bus, etc. The communication bus can be divided into address bus, data bus, control bus, etc. For ease of representation, Figure 5 The symbol is represented by only one double-headed arrow, but this does not mean that there is only one communication bus or one type of communication bus. The processor may be an integrated circuit chip with signal processing capabilities. In implementation, the steps of the above methods can be completed by integrated logic circuits in the processor's hardware or by software instructions. The processor can be a general-purpose processor, including a Central Processing Unit (CPU), a Network Processor (NP), etc.; it can also be a Digital Signal Processor (DSP), an Application Specific Integrated Circuit (ASIC), a Field-Programmable Gate Array (FPGA), or other programmable logic devices, discrete gate or transistor logic devices, or discrete hardware components. It can implement or execute the methods, steps, and logic block diagrams disclosed in the embodiments of this invention. The general-purpose processor can be a microprocessor or any conventional processor. The steps of the methods disclosed in the embodiments of this invention can be directly embodied in the execution of a hardware decoding processor, or executed by a combination of hardware and software modules in the decoding processor. The software modules can reside in random access memory, flash memory, read-only memory, programmable read-only memory, electrically erasable programmable memory, registers, or other mature storage media in the art. The storage medium is located in the memory, and the processor reads the information in the memory and, in conjunction with its hardware, completes the steps of the method described in the foregoing embodiments.
[0024] In embodiment three, this invention also provides a computer storage medium that stores computer-executable instructions. When these computer-executable instructions are called and executed by a processor, they cause the processor to implement the above-described string-type network-based energy storage security protection method. For specific implementation details, please refer to the method embodiment, which will not be repeated here. The computer program product of the string-grid energy storage safety protection method provided in this embodiment of the invention includes a computer storage medium storing program code. The instructions included in the program code can be used to execute the methods in the preceding method embodiments. For specific implementation, please refer to the method embodiments, which will not be repeated here.
[0025] Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the specific working process of the system and / or device described above can be referred to the corresponding process in the foregoing method embodiments, and will not be repeated here.
[0026] Furthermore, in the description of the embodiments of the present invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in the present invention based on the specific circumstances.
[0027] If the aforementioned functions are implemented as software functional units and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of this invention, essentially, or the part that contributes to the prior art, or a portion of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of this invention. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.
[0028] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention 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 or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.
Claims
1. A safety protection method for string-type grid-based energy storage, characterized in that, The method includes the following steps: Step S1: Analyze the grid connection status of the energy storage system at the current time node to determine whether the grid connection status of the energy storage system is grid-connected or off-grid. Step S2: When the grid connection status of the energy storage system is grid-connected, analyze the different power adjustment amounts of the energy storage system to obtain the active power adjustment amount and reactive power adjustment amount of the energy storage system. Step S3: Analyze different energy storage units based on active power adjustment and reactive power adjustment to obtain the actual active power adjustment and actual reactive power adjustment of different energy storage units. Step S4: When the grid connection status of the energy storage system is off-grid status, analyze the load status of the energy storage system at the current time node to determine whether the load status of the energy storage system is full load or not full load. Step S5: Based on the active power of the target load at different time points, predict the remaining working time of the energy storage system under the condition of not being fully loaded, and obtain the remaining energy supply time of the energy storage system.
2. The safety protection method for string-type grid-based energy storage according to claim 1, characterized in that, The analysis process in step S1 includes the following sub-steps: Step S101: Obtain the real-time electrical data of the energy storage system and the load electrical data of the target load at the current time point; Among them, the real-time electrical data are the real-time three-phase voltage, real-time three-phase current and real-time phase difference of the energy storage system, and the load electrical data are the load three-phase voltage, load three-phase current and load phase difference of the target load. Step S102: Multiply the fixed value by the real-time three-phase voltage to obtain the real-time line voltage of the energy storage system, and multiply the fixed value by the real-time three-phase current to obtain the real-time line current of the energy storage system. Step S103: Multiply the fixed value by the cosine of the real-time phase difference, the real-time line voltage, and the real-time line current respectively to obtain the real-time active power of the energy storage system at the current time node. The fixed value is multiplied by the sine value of the real-time phase difference, the real-time line voltage, and the real-time line current to obtain the real-time reactive power of the energy storage system at the current time point. Step S104: Repeat steps S102 and S103 to calculate the active power and reactive power of the target load. Step S105: Compare the real-time active power of the energy storage system with the load active power of the target load at the current time node, and compare the real-time reactive power of the energy storage system with the load reactive power of the target load at the current time node. If the real-time active power of the energy storage system at the current time node is greater than or equal to the load active power of the target load, and the real-time reactive power of the energy storage system at the current time node is greater than or equal to the load reactive power of the target load, then the grid connection status of the energy storage system at the current time node is recorded as the off-grid status. If the real-time active power of the energy storage system is less than the load active power of the target load at the current time point, or if the real-time reactive power of the energy storage system is less than the load reactive power of the target load at the current time point, then the grid connection status of the energy storage system at the current time point is recorded as the grid-connected status.
3. The safety protection method for string-type grid-based energy storage according to claim 2, characterized in that, The analysis process in step S2 includes the following sub-steps: Step S201: Obtain the rated frequency, real-time frequency, rated voltage and real-time voltage at the grid connection point in the power grid, and compare the real-time frequency at the grid connection point with the rated frequency and the real-time voltage at the grid connection point with the rated voltage. If the real-time frequency at the grid connection point is not equal to the rated frequency, but the real-time voltage is equal to the rated voltage, then proceed to step S202. If the real-time frequency at the grid connection point is equal to the rated frequency, but the real-time voltage is not equal to the rated voltage, then proceed to step S203. If the real-time frequency at the grid connection point is equal to the rated frequency and the real-time voltage is equal to the rated voltage, then no operation is performed. If the real-time frequency at the grid connection point is not equal to the rated frequency, and the real-time voltage is not equal to the rated voltage, then the active power adjustment and reactive power adjustment of the energy storage system can be obtained through analysis. Step S202: Analyze the droop coefficient of the energy storage converter based on the real-time frequency and the rated frequency to obtain the active power adjustment of the energy storage system. Step S203: Analyze the droop coefficient of different energy storage converters based on the real-time voltage and rated voltage, and obtain the reactive power adjustment of the energy storage system.
4. The safety protection method for string-type grid-based energy storage according to claim 3, characterized in that, The analysis process in step S202 includes the following sub-steps: Step S2021: Subtract the rated frequency from the real-time frequency to obtain the frequency deviation at the grid connection point; Step S2022: Obtain the frequency deviation threshold and the rated output power of the energy storage converter at the grid connection point, divide the frequency deviation threshold by the rated output power to obtain the droop coefficient of different energy storage converters, and sum the reciprocals of the different droop coefficients to obtain the frequency power factor of the energy storage system. Step S2023: Multiply the frequency deviation by the frequency power factor and take the absolute value to obtain the active power adjustment of the energy storage system.
5. A safety protection method for string-type grid-based energy storage according to claim 4, characterized in that, The analysis process in step S203 includes the following sub-steps: Step S2031: Subtract the rated voltage from the real-time voltage to obtain the voltage deviation at the grid connection point; Step S2032: Obtain the voltage deviation threshold and the rated reactive power of the energy storage converter at the grid connection point, divide the voltage deviation threshold by the rated reactive power to obtain the droop coefficient of different energy storage converters, and sum the reciprocals of the different droop coefficients to obtain the voltage power factor of the energy storage system. Step S2033: Multiply the voltage deviation by the voltage power factor and take the absolute value to obtain the reactive power adjustment of the energy storage system.
6. The safety protection method for string-type grid-based energy storage according to claim 1, characterized in that, The analysis process in step S3 includes the following sub-steps: Step S301: Obtain the rated capacity and real-time power consumption of different energy storage units at the current time node. Subtract the real-time power consumption from the rated capacity and divide by the rated capacity to obtain the remaining power ratio of different energy storage units at the current time node. Step S302: Divide the remaining power of the energy storage unit into a first power range, a second power range, and a third power range. Step S303: Energy storage units whose remaining power percentage falls within the first power range are designated as Level 1 energy storage units, energy storage units whose remaining power percentage falls within the second power range are designated as Level 2 energy storage units, and energy storage units whose remaining power percentage falls within the third power range are designated as Level 3 energy storage units.
7. A safety protection method for string-type grid-based energy storage according to claim 6, characterized in that, The values in the first power range are all greater than the values in the second power range, and the values in the second power range are all greater than the values in the third power range.
8. A safety protection method for string-type grid-based energy storage according to claim 7, characterized in that, The analysis process in step S3 also includes the following sub-steps: Step S304: Count the number of all energy storage units in the energy storage system and record it as the total number of energy storage units. Divide the active power adjustment by the total number of energy storage units to obtain the ideal active power adjustment of a single energy storage unit. Divide the reactive power adjustment by the total number of energy storage units to obtain the ideal reactive power adjustment of a single energy storage unit. Step S305: Divide the ideal active power adjustment of the three-level energy storage unit by two to obtain the actual active power adjustment of the corresponding energy storage unit, and divide the ideal active power adjustment of the three-level energy storage unit by two to obtain the actual reactive power adjustment of the corresponding energy storage unit. Step S306: Take the ideal active power adjustment of the secondary energy storage unit as the actual active power adjustment, and take the ideal reactive power adjustment of the secondary energy storage unit as the actual reactive power adjustment. Step S307: Add the actual active power adjustment of the secondary energy storage unit to the ideal active power adjustment of the primary energy storage unit to obtain the actual active power adjustment of the primary energy storage unit. The actual reactive power adjustment of the primary energy storage unit is obtained by summing the actual active power adjustment of the secondary energy storage unit with the ideal active power adjustment of the primary energy storage unit.
9. A safety protection method for string-type grid-based energy storage according to claim 1, characterized in that, The analysis process in step S4 includes the following sub-steps: Step S401: Obtain the active power and reactive power of the target load at the current time point. Then, the square of the sum of the square of the active power of the load and the square of the square of the reactive power of the load is taken to obtain the apparent power of the target load at the current time point. Step S402: Obtain the rated output power and rated apparent power of different energy storage converters, sum the different rated output powers to obtain the limit output power of the energy storage system, and sum the different rated apparent powers to obtain the limit apparent power of the energy storage system. Step S403: Compare the apparent power of the target load at the current time node with the limit apparent power of the energy storage system, and compare the active power of the target load at the current time node with the limit output power of the energy storage system. If the apparent power of the target load at the current time point is greater than or equal to the limit apparent power of the energy storage system, or the active power of the target load at the current time point is greater than or equal to the limit output power of the energy storage system, then the load state of the energy storage system at the current time point is recorded as full load state. If the apparent power of the target load at the current time point is less than the limit apparent power of the energy storage system, and the active power of the target load at the current time point is less than the limit output power of the energy storage system, then the load state of the energy storage system at the current time point is recorded as not fully loaded.
10. A safety protection method for string-type grid-based energy storage according to claim 1, characterized in that, The prediction process in step S5 includes the following sub-steps: Step S501: Obtain the active power of the target load at different time nodes, and subtract the active power of the target load at the previous time node from the active power of the target load at the current time node to obtain the change in the active power of the target load at the current time node. By analogy, the change in active power of the target load at different time points can be calculated; Step S502: Iterate through and compare the active power change of the target load at different time points to obtain the maximum value of the active power change. Divide the maximum value of the active power change by a fixed time interval to obtain the predicted active power change rate of the target load. Step S503: Subtract the load active power from the limit output power to obtain the remaining output power of the energy storage system at the current time node, and divide the remaining output power by the predicted active power change rate to obtain the remaining energy supply duration of the energy storage system.