CT wiring detection method and device, energy storage system and storage medium

Abstract

The invention relates to the technical field of energy storage, in particular to a CT wiring detection method and device, an energy storage system and a storage medium. The method comprises the following steps: controlling the i-th phase of an inversion unit to output first target power, and controlling the output power of other phases of the inversion unit to be 0; obtaining the ith-phase power grid power as first sampling power, and calculating a difference value between the first target power and the first sampling power; judging whether the difference value is within a preset range or not; if yes, it is judged that the ith phase of the CT is correctly connected to the ith phase of the power grid, and the orientation is positive; if not, calculating the sum of the first target power and the first sampling power to obtain a first power sum; judging whether the first power sum is within a preset range or not; if yes, the ith phase of the CT is judged to be connected to the ith phase of the power grid, but the orientation is opposite; and if not, judging that the ith phase of the CT is not connected to the ith phase of the power grid. By means of the method, CT wiring errors can be accurately recognized, and the operation stability and reliability of an energy storage system are improved.

Description

Technical Field

[0001] The present application relates to the field of energy storage technology, and in particular to a detection method, device, energy storage system, and storage medium for CT wiring. Background Art

[0002] The power system is a combination of the grid and energy storage system. Typically, the energy storage system includes storage batteries, inverter units, and current transformers (CTs). CTs perform critical current measurement and sampling functions in the system, and their installation quality directly impacts system reliability. It's important to note that CTs have specific phase sequence and polarity (direction) requirements. Wiring errors during installation will result in distorted current data collected by the energy storage system. This distorted data can further lead to decision errors in the power scheduling algorithm, potentially causing system malfunctions or even equipment damage. Summary of the Invention

[0003] In view of the above problems, the present application provides a CT wiring detection method, device, energy storage system and storage medium, which overcome the above problems or at least partially solve the above technical problem of needing to detect whether the CT wiring is incorrect.

[0004] According to one aspect of the present application, a method for detecting CT wiring is provided, which is applied to an energy storage system, wherein the energy storage system includes an energy storage battery, an inverter unit and a CT; the DC side of the inverter unit is connected to the energy storage battery, and the AC side is connected to the power grid; the sampling side of each phase of the CT is connected to the corresponding phase line of the power grid, and the feedback side is connected to the inverter unit. The method includes: when the energy storage system is not loaded, controlling the i-th phase of the inverter unit to output a first target power, and the output power of other phases of the inverter unit is 0; obtaining the i-th phase power of the power grid as a first sampling power, where the first sampling power is the product of the sampling current of the i-th phase CT and the i-th phase current. the product of the first target power and the first sampled power to obtain a first power difference; calculating the difference between the first target power and the first sampled power to obtain a first power difference; judging whether the first power difference is within a preset range, where the two end values of the preset range are a preset error value and zero, respectively; if so, judging that the i-th phase of the CT is correctly connected to the i-th phase of the grid and the direction is positive; if not, judging that the sum of the first target power and the first sampled power is obtained; judging whether the first power sum is within the preset range; if so, judging that the i-th phase of the CT is correctly connected to the i-th phase of the grid, but the direction is reversed; if not, judging that the i-th phase of the CT is not connected to the i-th phase of the grid.

[0005] In an optional manner, after determining that the i-th phase of the CT is not connected to the i-th phase of the grid, a second sampled power is obtained, where the second sampled power is the product of the sampled current of the j-th phase CT and the i-th phase grid voltage, where j≠i; the difference between the first target power and the second sampled power is calculated to obtain a first verification value; it is determined whether the first verification value is within the preset range; if so, it is determined that the j-th phase of the CT is wrongly connected to the i-th phase of the grid, and the direction is positive; if not, the sum of the first target power and the second sampled power is calculated to obtain a second power sum; it is determined whether the second power sum is within the preset range; if so, it is determined that the j-th phase of the CT is wrongly connected to the i-th phase of the grid, and the direction is reverse; if not, it is determined that the j-th phase of the CT is also not connected to the i-th phase of the grid; the j-th phase CT is replaced to obtain the second sampled power and the above steps are repeated until all phases of the CT are determined to be connected to the i-th phase of the grid.

[0006] In an optional embodiment, the method further includes: when it is determined that the i-th phase of the CT is correctly connected to the i-th phase of the power grid but in the reverse direction, calculating the correction power of the i-th phase power grid, wherein the correction power is the inverse of the product of the sampled current of the i-th phase CT and the i-th phase power grid voltage.

[0007] In an optional embodiment, the method further includes: when it is determined that the j-th phase of the CT is wrongly connected to the i-th phase of the power grid and the direction is positive, calculating the correction power of the i-th phase power grid, and the correction power is the product of the sampled current of the j-th phase CT and the i-th phase power grid voltage.

[0008] In an optional embodiment, the method further includes: when it is determined that the j-th phase of the CT is wrongly connected to the i-th phase of the power grid and the direction is reversed, calculating the correction power of the i-th phase power grid, wherein the correction power is the inverse of the product of the sampled current of the j-th phase CT and the i-th phase power grid voltage.

[0009] According to one aspect of an embodiment of the present application, a device for detecting CT wiring is provided, the device being applied to an energy storage system, the energy storage system comprising an energy storage battery, an inverter unit, and a CT, the DC side of the inverter unit being connected to the energy storage battery, and the AC side being connected to the grid; the sampling side of each phase of the CT being connected to the corresponding phase line of the grid, and the feedback side being connected to the inverter unit, the device comprising: a control module for controlling the i-th phase of the inverter unit to output a first target power when the energy storage system is not loaded, and the other phases of the inverter unit not to output power; an acquisition module for acquiring the i-th phase grid power as a first sampled power, the first sampled power being the product of the sampling current of the i-th phase CT and the sampling current of the i-th phase CT. a product of the phase grid voltages; a calculation module, configured to calculate the difference between the first target power and the first sampled power to obtain a first power difference; and further configured to calculate the sum of the first target power and the first sampled power to obtain a first power sum; a judgment module, configured to judge whether the first power difference is within a preset range, wherein the two end values of the preset range are a preset error value and zero, respectively; if so, judging that the i-th phase of the CT is correctly connected to the i-th phase of the grid and the direction is positive; and further configured to judge whether the first power sum is within the preset range, and if so, judging that the i-th phase of the CT is correctly connected to the i-th phase of the grid, but the direction is reversed; if not, judging that the i-th phase of the CT is not connected to the i-th phase of the grid.

[0010] According to one aspect of an embodiment of the present application, an energy storage system is provided, which includes: at least one processor, and a memory, wherein the memory is communicatively connected to the at least one processor, the memory stores instructions that can be executed by the at least one processor, and the instructions are executed by the at least one processor to enable the at least one processor to perform the method described above.

[0011] According to one aspect of an embodiment of the present application, a computer-readable storage medium is provided, wherein the computer-readable storage medium stores a computer program. When the computer program is executed by a processor, the processor performs the steps of the above method.

[0012] The beneficial effects of the present application include: through the CT wiring detection method provided in the embodiment of the present application, when the CT wiring is wrong, it can be accurately identified and then corrected when the CT wiring is wrong, thereby improving the operating stability and reliability of the energy storage system. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] One or more embodiments are exemplarily illustrated by pictures in the corresponding drawings. These exemplifications do not constitute limitations on the embodiments. Elements with the same reference numerals in the drawings are represented as similar elements. Unless otherwise stated, the figures in the drawings do not constitute proportional limitations.

[0014] Figure 1 is a schematic diagram of a power system provided in an embodiment of the present application;

[0015] Figure 2 This is a schematic diagram of the hardware structure of the control center provided in an embodiment of the present application;

[0016] Figure 3 This is a flow chart of a CT wiring detection method provided in an embodiment of the present application;

[0017] Figure 4 It is a flowchart of another CT wiring detection method provided in an embodiment of the present application. DETAILED DESCRIPTION

[0018] In order to make the purpose, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the embodiments described are part of the embodiments of the present application, rather than all the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not intended to limit the present application. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field fall within the scope of protection of this application.

[0019] In addition, the technical features involved in the embodiments of the present application described below can be combined with each other as long as they do not conflict with each other.

[0020] See also Figure 1 , Figure 1 1 is a schematic diagram of a dual-live-wire power system 100 provided in an embodiment of the present application. The power system 100 is applicable to the CT wiring detection method, the CT wiring error correction method, and the CT wiring detection device.

[0021] The power system 100 is a combination of a power grid 20 and an energy storage system 10. The energy storage system 10 includes a storage battery 11, an inverter unit 12, and a CT (current transformer). The DC side of the inverter unit 12 is connected to the storage battery 11, and the AC side (the grid end) is connected to the power grid 20. The power system 100 is a dual-live system. The L1 phase of the inverter unit 12 on the grid end is connected to the L1 phase of the power grid 20, the L2 phase of the inverter unit 12 on the grid end is connected to the L2 phase of the power grid 20, and the G phase of the inverter unit 12 on the grid end is connected to the G phase of the power grid 20. The sampling side of each phase of the CT is connected to the corresponding phase line of the power grid 20, and the feedback side is connected to the inverter unit 12.

[0022] CT is used to measure and sample current, and has clear phase sequence and polarity (direction) requirements. Figure 1In the dual-live power system 100 shown in FIG, the CT has an L1 phase and an L2 phase. CT1 corresponds to the L1 phase of the inverter unit, and CT2 corresponds to the L2 phase of the inverter unit. When the CT is properly connected, the L1 phase of the CT is connected to the L1 phase of the power grid 20, and the L2 phase of the CT is connected to the L2 phase of the power grid 20. For a three-phase power system, the CT has an L1 phase, an L2 phase, and an L3 phase. The L1 phase, L2 phase, and L3 phase of the CT correspond to the L1 phase, L2 phase, and L3 phase of the power grid, respectively.

[0023] In general, energy flowing from the inverter unit 12 to the grid 20 is considered a positive direction, and energy flowing from the grid 20 to the inverter unit 12 is considered a negative direction. Therefore, when the grid 20 charges the energy storage battery 11 through the inverter unit 12, the current sampled by the CT should be a negative value; when the energy storage battery 11 feeds power to the grid 20 through the inverter unit, the current sampled by the CT should be a positive value.

[0024] During the installation of CT, there is a possibility that CT is connected incorrectly, reversely or missed, such as CT1 is connected incorrectly to the L2 phase of the power grid, CT1 is reversely connected to the L1 phase of the power grid, or CT1 is not connected to any phase of the power grid.

[0025] In some embodiments, the power system 100 also includes a load 30, which is connected to the load end of the inverter unit 12, that is, the L1 phase of the load 30 is connected to the L1 phase of the load end of the inverter unit 12, the L2 phase of the load 30 is connected to the L2 phase of the load end of the inverter unit 12, and the G phase of the load 30 is connected to the G phase of the load end of the inverter unit 12.

[0026] It is worth noting that the energy storage system 10 further includes a control center 13, i.e., an energy management system, which is connected to the inverter unit 12 and the energy storage battery 11. The control center 13 can be used to issue the target power required to be executed by the inverter unit 12.

[0027] See also Figure 2 , Figure 2 This is a hardware structure diagram of the control center 13 provided in the embodiment of the present application, which can execute the CT wiring detection method and the CT wiring error correction method. The control center 13 includes: at least one processor 131 and a memory 132 ( Figure 2 A bus connection and a processor are used as an example). A person skilled in the art will understand that Figure 2 The structure shown is only for illustration and does not limit the structure of the control center 13. For example, the control center 13 may also include Figure 2 More or fewer components than shown, or with Figure 2 Different configurations shown.

[0028] The processor 131 is used to provide computing and control capabilities, and to control the control center 13 to execute any method provided in the following application embodiments.

[0029] It is understandable that the processor 131 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, discrete hardware components.

[0030] The memory 132 is a non-transient computer-readable storage medium that can be used to store non-transient software programs, non-transient computer executable programs and modules, such as program instructions / modules corresponding to the various calculation methods in the embodiments of the present application. The processor 131 can implement the various calculation methods in any of the following method embodiments by running the non-transient software programs, instructions and modules stored in the memory 132. The memory 132 may include a high-speed random access memory and may also include a non-transient memory, such as at least one disk storage device, a flash memory device, or other non-transient solid-state storage device. In some embodiments, the memory 132 may also include a memory remotely arranged relative to the processor, and these remote memories may be connected to the processor via a network. Examples of the above-mentioned network include, but are not limited to, the Internet, an intranet, a local area network, a mobile communication network and a combination thereof.

[0031] Example 2

[0032] An embodiment of the present application further provides a non-volatile computer-readable storage medium, wherein the non-volatile computer-readable storage medium stores computer-executable instructions, which are used by the power system to execute the various calculation methods in any of the following method embodiments.

[0033] An embodiment of the present application provides a computer program product, including a computing program stored on a non-volatile computer-readable storage medium, wherein the computer program includes program instructions. When the program instructions are executed by a computer, the computer is caused to perform each computing method in any of the following method embodiments.

[0034] Through the description of the above embodiments, it can be clearly understood by those skilled in the art that each embodiment can be implemented by means of software plus a general hardware platform, and of course can also be implemented by hardware. It can be understood by those skilled in the art that all or part of the processes in the above embodiment methods can be completed by instructing the relevant hardware through a computer program, and the program can be stored in a computer-readable storage medium. When the program is executed, it can include the processes of the embodiments of the above methods. Among them, the storage medium can be a magnetic disk, an optical disk, a read-only memory (ROM) or a random access memory (RAM), etc.

[0035] Example 3

[0036] The following is a discussion of the CT connection detection method provided in the embodiment of the present application. For a dual-phase power system, phase i is L1 or L2, and phase j is L1 or L2. For a three-phase power system, phase i is any one of L1, L2, and L3, and phase j is any one of L1, L2, and L3. Figure 3 , Figure 3 : is a flow chart of a method for detecting CT wiring provided in an embodiment of the present application, the method comprising the following steps:

[0037] Step S1 : When the energy storage system is not loaded, controlling the i-th phase of the inverter unit to output a first target power, and the output powers of other phases of the inverter unit are 0.

[0038] The energy storage system being off-load means that the energy storage system does not supply power to the load, but the grid can supply power to the energy storage battery through the inverter unit, or the energy storage system can also feed power to the grid.

[0039] When the output power of the inverter unit's phase i is selected, the output power of the other phases of the inverter unit is 0, and the CT phase-by-phase detection is performed. For example, if the inverter unit's phase L1 outputs power, phases L2 and L3 do not output power.

[0040] The first target power is configured based on the maximum charge and discharge power that the energy storage battery can withstand and the maximum allowable charge and discharge power of the inverter unit. For example, when the grid charges the energy storage battery through the inverter unit, the maximum charging power that the energy storage battery can withstand is 6000W, the maximum allowable charging power of the inverter unit is 4500W, and the inverter unit's L1 phase output power is selected. The power allocated to the inverter unit's L1 phase is -4500W, that is, the obtained first target power of the inverter unit's L1 phase is -4500W, and the other phases of the inverter unit do not output power.

[0041] It can be understood that in the above example, if the L2 phase output power of the inverter unit is selected, the power allocated to the L2 phase of the inverter unit is -4500W, that is, the second target power of the L2 phase of the inverter unit that can be obtained is -4500W, and the other phases of the inverter unit do not output power.

[0042] Step S2: Acquire the i-th phase grid power as a first sampled power, where the first sampled power is the product of the sampled current of the i-th phase CT and the i-th phase grid voltage.

[0043] When the inverter outputs power on phase i, energy flows through the grid on phase i. When the CT on phase i is connected to the grid, it detects a corresponding current with magnitude and direction. If the CT on phase i is not connected to the grid, the current detected by the CT on phase i should be close to zero.

[0044] The i-th phase grid power = the i-th phase CT sampling current * the i-th phase grid voltage.

[0045] Step S3: Calculate the difference between the first target power and the first sampled power to obtain a first power difference.

[0046] The first power difference is calculated as follows: first power difference=first target power−first sampling power.

[0047] Step S4, determining whether the first power difference is within a preset range, where the two end values of the preset range are a preset error value and zero respectively. If yes, execute the following step S5; if not, execute the following step S6.

[0048] The preset error value can be set through experience. For example, if the preset error value is -150W, the preset range is [-150, 0]; for another example, if the preset error value is 150W, the preset range is [0, 150].

[0049] S5, determining whether the i-th phase of the CT is correctly connected to the i-th phase of the grid and the direction is positive.

[0050] When the first power difference is within the preset range, it can be determined that the i-th phase of the CT is correctly connected to the i-th phase of the power grid, and the direction is positive. If the first power difference exceeds the preset range, it can actually be determined that the i-th phase of the CT is incorrectly connected, which includes three situations: the i-th phase of the CT is missed, wrongly connected, and the phase sequence is correct but the direction is reversed; missed connection means that the i-th phase of the CT is not connected to any phase of the power grid, wrong connection means that the i-th phase of the CT is wrongly connected to other phases of the power grid, and correct phase sequence but reverse direction means that the i-th phase of the CT is connected to the i-th phase of the power grid, but the direction is reversed. The embodiment of the present application has been further verified, that is, when the first power difference exceeds the preset range, the following steps S6-S8 are executed to identify the situation that the i-th phase of the CT is correctly connected but the direction is reversed.

[0051] Step S6: Calculate the sum of the first target power and the first sampling power to obtain a first power sum.

[0052] The first power sum is calculated as follows: first power sum=first target power+first sampling power.

[0053] Step S7, determining whether the first power sum is within the preset range, if so, executing the following step S8, if not, executing the following step S9.

[0054] Step S8 , determining that the i-th phase of the CT is connected to the i-th phase of the grid, but in a reverse direction.

[0055] When a difference between the first target power and the first sampled power is calculated and a first power difference is outside the preset range, but a first power sum obtained by calculating the sum of the first target power and the first sampled power is within the preset range, it is determined that the i-th phase of the CT is connected to the i-th phase of the power grid, but in a reverse direction.

[0056] In step S9, it is determined that the i-th phase of the CT is not connected to the i-th phase of the power grid.

[0057] After determining that the i-th phase of the CT is not connected to the i-th phase of the grid, if Figure 4 As shown, it is also necessary to go through the following steps S10-S17 to detect which phase CT is connected to the i-th phase of the power grid, so as to subsequently correct the power of the i-th phase power grid.

[0058] Step S10 : obtaining a second sampled power, where the second sampled power is the product of the sampled current of the j-th phase CT and the i-th phase grid voltage, where j≠i.

[0059] The j-th phase CT is different from the i-th phase CT. Assuming that the i-th phase CT is CT1, for a dual-live system, the j-th phase CT is CT2; for a three-phase system, the j-th phase CT is CT2 or CT3.

[0060] It is worth noting that the sampling current of the j-th phase CT also has magnitude and direction.

[0061] Step S11: Calculate the difference between the first target power and the second sampling power to obtain a first verification value.

[0062] The first verification value is calculated as follows: first verification value=first target power-second sampling power.

[0063] Step S12, determining whether the first verification value is within the preset range, if so, executing the following step S13, if not, executing the following step S14.

[0064] The preset range is the same as the preset range in step S4.

[0065] Step S13 , determining that the j-th phase of the CT is mistakenly connected to the i-th phase of the grid, and the direction is positive.

[0066] If the first power difference is within the preset range, it indicates that the jth phase of the CT is incorrectly connected to the ith phase of the grid in a positive direction. If the first power difference exceeds the preset range, it can be determined that the jth phase of the CT has the following two possible scenarios: 1) the jth phase of the CT is incorrectly connected to the ith phase of the grid in a negative direction; or 2) the jth phase of the CT is not connected to the ith phase of the grid. Therefore, it is necessary to further determine whether the jth phase of the CT falls into the first scenario.

[0067] Step S14: Calculate the sum of the first target power and the second sampled power to obtain a second power sum.

[0068] The second power sum is calculated as follows: second power sum=first target power+second sampling power.

[0069] Step S15, determining whether the second power sum is within the preset range, if so, executing the following step S16, if not, executing the following step S17.

[0070] Step S16 , determining that the j-th phase of the CT is mistakenly connected to the i-th phase of the power grid, and the direction is reversed.

[0071] When a first verification value obtained by calculating the difference between the first target power and the second sampled power is outside the preset range, but a second power sum obtained by calculating the sum of the first target power and the second sampled power is within the preset range, it is determined that the j-th phase of the CT is connected to the i-th phase of the power grid in a reverse direction.

[0072] Step S17: If not, it is determined that the j-th phase of the CT is not connected to the i-th phase of the grid.

[0073] Step S18: Replace the j-th phase CT to obtain the second sampled power and repeat the above steps S10-S17 until all phases of the CT are determined to be connected to the i-th phase of the power grid.

[0074] Assuming that the i-th phase is L1 and the j-th phase is L2, for a dual-live-wire system, this step has completed the detection of whether all CT phases are connected to the L1 phase of the grid.

[0075] If the power system is a three-phase system, it is also necessary to use phase L3 as the jth phase to repeat the above steps S10-S17 until all phases of the CT are determined to be connected to the i-th phase of the grid.

[0076] If all phases of the CT are judged to be not connected to the i-th phase of the grid, the i-th phase grid power cannot be calibrated and manual adjustment is required before retesting.

[0077] After determining which phase of the CT is connected to phase i of the grid, replace the output phase of the inverter unit and repeat the above steps to detect the connection relationship between all phases of the CT and all phases of the grid without omission.

[0078] In order to facilitate readers to understand the inventive concept of the present application, the CT wiring error detection method of the present application is now described with reference to specific examples.

[0079] Working condition 1: Dual-live power system, the energy storage system is not connected to the load and is in charging state, CT1 is missing; CT2 is connected to the grid line L1 and the direction is positive.

[0080] The control center sends the target power, the first target power of the inverter unit L1 phase = -500 W, and the power output of the inverter unit L2 phase is 0 W. The preset range is [-150 W, 0 W].

[0081] Because CT1 is not connected, the first sampled power = 0 W. The first power difference = -500 W, which is not within the preset range of -150 W to 0. Further determination is made to see whether the first power sum formed by the first target power + the first sampled power is within the preset range of -150 W to 0: -500 + 0 = -500 W. This is also not within the preset range of -150 W to 0. Therefore, it can be determined that CT1 is not connected to phase L1 of the power grid.

[0082] Continuing to obtain the second power, CT2 is connected to the grid line L1, so CT2 has current. The second sampled power = CT2 phase sampled current * L1 phase grid voltage = -480W. Subtracting the second sampled power from the first target power yields the first verification value: -500W - (-480W) = -20W. Since the first verification value is within the preset range of -150W to 0, it is determined that CT2 is incorrectly connected to the grid phase L1 and is facing in the positive direction.

[0083] In summary, according to the CT wiring error detection method, it can be determined that CT1 is missing and CT2 is incorrectly connected to the grid phase L1. Since CT1 is missing, it affects the overall function of the energy storage system, so it is prompted that CT1 is missing.

[0084] Working condition 2: Dual-live power system, the energy storage system is not connected to the load and is in the discharge state, CT1 is connected to the L2 phase of the grid in the positive direction; CT2 is connected to the L1 phase of the grid in the negative direction.

[0085] The control center issues the target power for the first time. The first target power of the inverter unit L1 phase is 500W, the power output of the inverter unit L2 phase is 0W, and the preset range is [0W, 150W].

[0086] Because CT1 is connected to the grid's L2 phase, and the inverter's L2 phase power output is 0 W, the current detected by CT1 is 0, resulting in the first sampled power being 0 W. The first power difference, 500 - 0 = 500 W, is outside the preset range of 0 to 150 W. Further testing is performed to determine whether the first target power + the first sampled power is within the preset range of 0 to 150 W: 500 + 0 = 500 W. This result is inconsistent with the determination, so it can be determined that CT1 is not connected to the grid's L1 phase.

[0087] Continuing to obtain the second power, CT2 is connected to the grid line L1, so CT2 has current. The second sampled power = CT2 phase sampled current * L1 phase grid voltage = -480W. The difference between the first target power and the second sampled power yields the first verification value: 500 - (-480) = 980W. This first verification value is not within the preset range of 0 to 150W. Therefore, the sum of the first target power and the second sampled power is calculated: 500 + (-480) = 20W. This is within the preset range of 0 to 150W, so it can be determined that CT2 is connected to the grid phase L1 and in the reverse direction.

[0088] The output phase of the inverter unit is changed. The control center sends the target power for the second time. The first target power of the inverter unit L2 phase is 500W, the power output of the inverter unit L1 phase is 0W, and the preset range is [0W, 150W].

[0089] Since the inverter unit's L1 phase power output is 0 W, the current detected by CT2 is 0, resulting in the first sampled power = 0 W. The first power difference, 500 - 0 = 500 W, is outside the preset range of 0 to 150 W. Further determination is made to see whether the first target power + the first sampled power is within the preset range of 0 to 150 W: 500 + 0 = 500 W. This result is inconsistent with the determination, so it can be determined that CT2 is not connected to the L2 phase of the grid.

[0090] Continuing to obtain the second power, CT1 is connected to the L2 phase of the power grid, so CT1 has current. The second sampled power = CT1 phase sampled current * L2 phase power grid voltage = 480W. The difference between the first target power and the second sampled power yields the first verification value: 500 - 480 = 20W. This first verification value is within the preset range of 0 to 150W, so it can be determined that CT1 is connected to the L2 phase of the power grid and the direction is positive.

[0091] In summary, according to the method for detecting CT wiring errors, it can be known that CT1 is connected to the L2 phase of the power grid in the positive direction; CT2 is connected to the L1 phase of the power grid in the negative direction.

[0092] Example 4

[0093] The present application also provides a method for correcting grid power after a CT wiring error occurs, specifically comprising the following steps:

[0094] In step A10 , when it is determined that the i-th phase of the CT is correctly connected to the i-th phase of the grid and the direction is positive, the i-th phase grid power does not need to be corrected.

[0095] In step A20 , when it is determined that the i-th phase of the CT is connected to the i-th phase of the grid but in a reverse direction, the correction power of the i-th phase grid power is the inverse of the product of the sampled current of the i-th phase CT and the i-th phase grid voltage.

[0096] Step A30: When it is determined that the jth phase of the CT is incorrectly connected to the ith phase of the grid and the direction is positive, the correction power of the ith phase grid power is the product of the sampled current of the jth phase CT and the ith phase grid voltage.

[0097] Step A40: When it is determined that the jth phase of the CT is incorrectly connected to the ith phase of the grid and the direction is reversed, the correction power of the ith phase grid power is the inverse of the product of the sampled current of the jth phase CT and the ith phase grid voltage.

[0098] Example 5

[0099] The following discusses a device for detecting CT wiring errors provided in an embodiment of the present application. A schematic diagram of a device for detecting CT wiring errors provided in an embodiment of the present application is provided. The device for detecting CT wiring errors is applied to an energy storage system, wherein the energy storage system includes an energy storage battery, an inverter unit, and a CT. The DC side of the inverter unit 12 is connected to the energy storage battery 11, and the AC side (grid end) is connected to the grid 20. The sampling side of each phase of the CT is connected to the corresponding phase line of the grid, and the feedback side is connected to the inverter unit. The device for detecting CT wiring includes:

[0100] The control module is used to control the i-th phase of the inverter unit to output the first target power when the energy storage system is not loaded, and the other phases of the inverter unit do not output power.

[0101] The acquisition module is configured to acquire the i-th phase grid power as a first sampled power, where the first sampled power is the product of the sampled current of the i-th phase CT and the i-th phase grid voltage.

[0102] The calculation module is used to calculate the difference between the first target power and the first sampling power to obtain a first power difference; and is also used to calculate the sum of the first target power and the first sampling power to obtain a first power sum.

[0103] The judgment module is configured to judge whether the first power difference is within a preset range, where the two end values of the preset range are a preset error value and zero respectively; if so, it is determined that the i-th phase of the CT is correctly connected to the i-th phase of the grid and the direction is positive.

[0104] It is also used to determine whether the first power sum is within the preset range. If so, it is determined that the i-th phase of the CT is correctly connected to the i-th phase of the power grid, but in the reverse direction; if not, it is determined that the i-th phase of the CT is not connected to the i-th phase of the power grid.

[0105] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Based on the idea of the present application, the technical features in the above embodiments or different embodiments can also be combined, the steps can be implemented in any order, and there are many other variations in different aspects of the present application as above, which are not provided in detail for the sake of simplicity. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A method for detecting CT wiring, characterized in that: The method is applied to an energy storage system, which includes an energy storage battery, an inverter unit, and a CT; the DC side of the inverter unit is connected to the energy storage battery, and the AC side is connected to the power grid; the sampling side of each phase of the CT is connected to the corresponding phase line of the power grid, and the feedback side is connected to the inverter unit. The method includes: When the energy storage system is not loaded, controlling the i-th phase of the inverter unit to output a first target power, and the output powers of other phases of the inverter unit are 0; Acquire the i-th phase grid power as a first sampled power, where the first sampled power is the product of the sampled current of the i-th phase CT and the i-th phase grid voltage; Calculating a difference between the first target power and the first sampled power to obtain a first power difference; Determining whether the first power difference is within a preset range, where two end values of the preset range are a preset error value and zero respectively; If so, it is determined that the i-th phase of the CT is correctly connected to the i-th phase of the grid, and the direction is positive; If not, calculating the sum of the first target power and the first sampled power to obtain a first power sum; Determining whether the first power sum is within a preset range; If so, it is determined that the i-th phase of the CT is connected to the i-th phase of the grid, but in the opposite direction; If not, it is determined that the i-th phase of the CT is not connected to the i-th phase of the grid.

2. The method according to claim 1, characterized in that After determining that the i-th phase of the CT is not connected to the i-th phase of the grid, obtaining a second sampled power, where the second sampled power is the product of the sampled current of the j-th phase CT and the i-th phase grid voltage, where j≠i; Calculating a difference between the first target power and the second sampled power to obtain a first verification value; Determining whether the first verification value is within the preset range; If so, it is determined that the jth phase of the CT is wrongly connected to the ith phase of the grid, and the direction is positive; If not, calculating the sum of the first target power and the second sampled power to obtain a second power sum; Determining whether the second power sum is within the preset range; If so, it is determined that the jth phase of the CT is wrongly connected to the ith phase of the grid, and the direction is reversed; If not, it is determined that the jth phase of the CT is also not connected to the ith phase of the grid; The j-th phase CT is replaced to obtain the second sampled power and the above steps are repeated until all phases of the CT are determined to be connected to the i-th phase of the grid.

3. The method according to claim 2, characterized in that The method further comprises: When it is determined that the i-th phase of the CT is connected to the i-th phase of the grid but in a reverse direction, a correction power of the i-th phase grid power is calculated, where the correction power is the inverse of the product of the sampled current of the i-th phase CT and the i-th phase grid voltage.

4. The method according to claim 2, characterized in that The method further comprises: When it is determined that the jth phase of the CT is wrongly connected to the ith phase of the grid and the direction is positive, the correction power of the ith phase grid power is calculated, and the correction power is the product of the sampled current of the jth phase CT and the ith phase grid voltage.

5. The method according to claim 2, characterized in that The method further comprises: When it is determined that the jth phase of the CT is mistakenly connected to the ith phase of the power grid and the direction is reversed, the correction power of the ith phase power grid is calculated, and the correction power is the inverse of the product of the sampled current of the jth phase CT and the ith phase power grid voltage.

6. A CT wiring detection device, characterized in that: The device is applied to an energy storage system, which includes an energy storage battery, an inverter unit, and a CT. The DC side of the inverter unit is connected to the energy storage battery, and the AC side is connected to the power grid. The sampling side of each phase of the CT is connected to the corresponding phase line of the power grid, and the feedback side is connected to the inverter unit. The device includes: a control module, configured to control the i-th phase of the inverter unit to output a first target power and control other phases of the inverter unit not to output power when the energy storage system is not loaded; an acquisition module, configured to acquire an i-th phase grid power as a first sampled power, where the first sampled power is a product of a sampled current of the i-th phase CT and an i-th phase grid voltage; a calculation module, configured to calculate a difference between the first target power and the first sampled power to obtain a first power difference; and further configured to calculate a sum of the first target power and the first sampled power to obtain a first power sum; a determination module, configured to determine whether the first power difference is within a preset range, where the two end values of the preset range are a preset error value and zero, respectively; and if so, determine that the i-th phase of the CT is correctly connected to the i-th phase of the grid and is in a positive direction; It is also used to determine whether the first power sum is within the preset range. If so, it is determined that the i-th phase of the CT is correctly connected to the i-th phase of the power grid, but in the reverse direction; if not, it is determined that the i-th phase of the CT is not connected to the i-th phase of the power grid.

7. An energy storage system, characterized in that: include: at least one processor; as well as A memory, the memory being communicatively connected to the at least one processor, the memory storing instructions executable by the at least one processor, the instructions being executed by the at least one processor so that the at least one processor can execute the method according to any one of claims 1 to 5.

8. A computer-readable storage medium, characterized in that The computer-readable storage medium stores a computer program. When the computer program is executed by a processor, the processor performs the steps of the method according to any one of claims 1 to 5.

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