Reactive compensation equipment and abnormal capacitor detection method and system
By coordinating the detection meters and controllers, the reactive power detection method was used to solve the problem of reactive power compensation failure caused by capacitor cell capacitance decay. This enabled accurate detection and timely alarm of the capacitor cells, ensuring the reliability of the reactive power compensation equipment and the quality of power supply.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-06-23
- Publication Date
- 2026-03-27
AI Technical Summary
The problem of reactive power compensation failure caused by capacitance decay in capacitor units of reactive power compensation equipment is that existing technologies are unable to effectively detect and handle abnormal capacitors.
By coordinating the testing of electricity meters and controllers, reactive power detection methods are used to determine whether the capacitance value of capacitor units is normal. This includes timed inspections and anomaly identification mechanisms to ensure that testing is performed only when one capacitor unit is connected to the AC bus, and to promptly alarm and shut down the system in case of an anomaly.
It enables accurate detection and timely alarm of capacitor unit capacitance value, ensuring the accuracy of reactive power compensation and power supply quality, and avoiding repeated detection and impact of abnormal capacitor units.
Smart Images
Figure CN121749256A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to the technical field of reactive power compensation, in particular to a reactive power compensation device, an abnormal capacitor detection method and system. BACKGROUND
[0002] The reactive power compensation device includes multiple capacitor units, and the capacitor units are used to compensate the reactive power of the power grid. When compensating the reactive power, one or more capacitor units are selected from the multiple capacitor units to compensate the reactive power of the power grid each time. Therefore, according to the demand for reactive power compensation of the power grid, the capacitor units need to be connected or cut off. With the increase of the number of times of connecting or cutting off the capacitor units, the capacitance of the capacitor units may be attenuated. When the capacitance of the capacitor units is greatly attenuated, the problem of failure of reactive power compensation will be caused. SUMMARY
[0003] Therefore, the present application provides a reactive power compensation device, an abnormal capacitor detection method and system, which can detect whether the capacitance of the capacitor units is abnormal.
[0004] The present application provides a reactive power compensation device, which includes a controller, a detection ammeter and multiple capacitor units. The first end of each capacitor unit in the multiple capacitor units is connected to the first end of the detection ammeter, and the second end of the detection ammeter is used to be connected to an AC bus. The controller is configured to, when only one capacitor unit in the multiple capacitor units is connected to the AC bus, judge whether the capacitance of the connected capacitor unit is normal according to the reactive power detected by the detection ammeter.
[0005] In a possible implementation, the controller is further configured to, when a timing inspection time arrives, control the connected capacitor units in the multiple capacitor units to be cut off, and then control each capacitor unit in the multiple capacitor units to be connected to the AC bus in turn, so that only one capacitor unit is connected to the AC bus.
[0006] In a possible implementation, the controller is further configured to, during the process of reactive power compensation of the reactive power compensation device, detect whether only one capacitor unit is connected to the AC bus.
[0007] In a possible implementation, the controller is configured to read the reactive power detected by the detection ammeter N times. When N is an odd number greater than or equal to 3, the reactive power located in the middle after sorting the N reactive powers in size is used to judge whether the capacitance of the capacitor unit is normal. When N is an even number greater than 3, the two reactive powers located in the middle after sorting the N reactive powers in size are used to judge whether the capacitance of the capacitor unit is normal.
[0008] Or,
[0009] The controller is configured to read the reactive power detected by the detection meter N times, where N is an integer greater than or equal to 2, and determine whether the capacitance value of the capacitor unit is normal based on the average value of the N reactive power readings.
[0010] or,
[0011] The controller is configured to read the reactive power detected by the detection meter N times, where N is an integer greater than or equal to 2, compare the N reactive power values with a threshold, and determine whether the capacitance value of the capacitor unit is normal based on the comparison results.
[0012] In one possible implementation, the controller is configured to obtain the capacitance value of the capacitor cell based on the reactive power, and to determine that the capacitor cell is abnormal when the capacitance value is less than or equal to half of the nominal capacitance value of the capacitor cell.
[0013] In one possible implementation, the controller is further configured to set an abnormality flag for the capacitor unit when it is determined that the capacitor unit is abnormal, and to skip the capacitor unit with the abnormality flag when checking whether the capacitance value of the capacitor unit is normal the next time.
[0014] One possible implementation is that each of the plurality of said capacitor units has a number;
[0015] The controller is configured to arrive at the scheduled inspection time and control only one capacitor unit to connect to the AC bus at a time, according to the number.
[0016] This application embodiment also provides a method for detecting abnormal capacitance, including: when only one capacitor unit among multiple capacitor units is currently connected to the AC bus, determining whether the capacitance value of the connected capacitor unit is normal based on the reactive power detected by the detection meter; the first end of the multiple capacitor units is connected to the first end of the detection meter, and the second end of the detection meter is used to connect to the AC bus.
[0017] One possible implementation method, the detection method further includes: when the timed inspection time arrives, controlling all the connected capacitor units in the plurality of capacitor units to be switched off, and then controlling each capacitor unit in the plurality of capacitor units to be connected to the AC bus in sequence, so that only one capacitor unit is currently connected to the AC bus.
[0018] One possible implementation method, the detection method further includes: during the reactive power compensation process through multiple capacitor units, detecting whether only one capacitor unit is currently connected to the AC bus.
[0019] One possible implementation involves determining whether the capacitance value of the connected capacitor unit is normal based on the reactive power detected by the detection meter, including: reading the reactive power detected by the detection meter N times; when N is an odd number greater than or equal to 3, determining whether the capacitance value of the capacitor unit is normal based on the middle reactive power value after sorting the N reactive power values; when N is an even number greater than 3, determining whether the capacitance value of the capacitor unit is normal based on the two middle reactive power values after sorting the N reactive power values.
[0020] or,
[0021] Read the reactive power detected by the detection meter N times, and determine whether the capacitance value of the capacitor unit is normal based on the average value of the N reactive power values, where N is an integer greater than or equal to 2;
[0022] or,
[0023] The reactive power detected by the detection meter is read N times, and the N reactive power values are compared with the threshold value respectively. Based on the comparison results, it is determined whether the capacitance value of the capacitor unit is normal. N is an integer greater than or equal to 2.
[0024] One possible implementation involves determining whether the capacitance value of the connected capacitor unit is normal based on the reactive power detected by the detection meter, including:
[0025] The capacitance value of the capacitor unit is obtained based on the reactive power.
[0026] When the capacitance value is less than or equal to half of the nominal capacitance value of the capacitor cell, the capacitor cell is determined to be faulty.
[0027] One possible implementation method further includes: when the capacitor unit is determined to be abnormal, setting an abnormality flag for the capacitor unit, and skipping the capacitor unit with the abnormality flag when checking whether the capacitance value of the capacitor unit is normal in the next test.
[0028] One possible implementation involves controlling each of the plurality of capacitor units to be connected to the AC bus sequentially, including: controlling only one capacitor unit to be connected to the AC bus at a time, according to the number of each capacitor unit in the plurality of capacitor units.
[0029] This application embodiment also provides a photovoltaic system, including the reactive power compensation device described above, and an inverter; the reactive power compensation device is connected to the AC side of the inverter.
[0030] This application also provides a control device, including a processor and a memory, wherein the memory is used to store programs, instructions or code, and the processor is used to execute the programs, instructions or code in the memory to perform the methods described above.
[0031] This application also provides a computer-readable storage medium storing a computer program, which is loaded by a processor to execute the methods described above.
[0032] The reactive power compensation device provided in this application embodiment utilizes a detection meter and a controller to detect whether the capacitance value of a connected capacitor unit is normal when only one capacitor unit is connected to the AC bus. The hardware is simple and the detection method is easy to implement. Furthermore, when an abnormality occurs in a capacitor unit, an alarm can be triggered promptly, causing the abnormal capacitor unit to stop working, ensuring the accuracy of reactive power compensation and thus improving power supply quality. Attached Figure Description
[0033] Figure 1 This is a schematic diagram of a reactive power compensation device provided in an embodiment of this application;
[0034] Figure 2 A schematic diagram of yet another reactive power compensation device provided in an embodiment of this application;
[0035] Figure 3 A flowchart illustrating a method for detecting abnormal capacitance provided in an embodiment of this application;
[0036] Figure 4 A flowchart of another abnormal capacitance detection method provided in an embodiment of this application;
[0037] Figure 5 A schematic diagram of a photovoltaic system provided in an embodiment of this application;
[0038] Figure 6 This is a schematic diagram of a control device provided in an embodiment of this application. Detailed Implementation
[0039] To make the above-mentioned objectives, features and advantages of this application more apparent and understandable, the embodiments of this application will be further described in detail below with reference to the accompanying drawings and specific implementation methods.
[0040] See Figure 1 The figure is a schematic diagram of a reactive power compensation device provided in an embodiment of this application.
[0041] The reactive power compensation device 1000 provided in this application embodiment includes: a controller 200, a detection meter 100, and multiple capacitor units.
[0042] This application does not specifically limit the number of capacitor units, and may include capacitor unit 1, capacitor unit 2, capacitor unit 3, up to capacitor unit n. Here, n is an integer greater than or equal to 2. The first end of multiple capacitor units is connected to the first end of the detection meter 100, and the second end of the detection meter 100 is used to connect to the AC bus. Additionally, loads can be connected to the AC bus, which is connected to the low-voltage side of the transformer. The high-voltage side of the transformer is used to connect to the power grid.
[0043] The embodiments of this application do not specifically limit the application scenarios of reactive power compensation equipment, but can be applied to distributed photovoltaic systems, such as industrial and commercial photovoltaic systems, specifically rooftop photovoltaic systems of factories.
[0044] When capacitor units 1 through n are all connected to the AC bus, the reactive power detected by the meter will increase; conversely, when capacitor units are disconnected, the reactive power detected by the meter will decrease. Disconnection means that the capacitor unit is electrically disconnected from the AC bus.
[0045] A capacitor unit can include capacitors connected in series and a switch, and is an electrical device. The switch can be controlled by the controller 200. The capacitance values of the capacitors in multiple capacitor units can be different or the same, with different capacitance values corresponding to different reactive power. When a capacitor unit is connected to the AC bus, it indicates that a corresponding capacitive load has been connected to the low-voltage grid connection point of the transformer. The capacitive load is used to offset the inductive load of the load and perform reactive power compensation.
[0046] This application does not specifically limit whether the capacitance values of each capacitor unit are equal; for example, they can be unequal, thus forming different combinations of capacitor units for reactive power compensation. For instance, capacitor unit 1 corresponds to a reactive power of 10 kvar, capacitor unit 2 corresponds to a reactive power of 20 kvar, and capacitor unit 3 corresponds to a reactive power of 30 kvar. Then, when capacitor unit 1 is turned on, the reactive power displayed on the meter increases by 10 kvar. When capacitor unit 2 is turned off, the reactive power detected by the meter decreases by 20 kvar.
[0047] The controller 200 is configured to determine whether the capacitance value of the connected capacitor unit is normal based on the reactive power detected by the detection meter when only one capacitor unit among multiple capacitor units is currently connected to the AC bus.
[0048] It should be understood that when only one capacitor unit is connected, the reactive power detected by the detection meter 100 is the reactive power corresponding to the connected capacitor unit. Therefore, the capacitance value of the connected capacitor unit can be obtained based on the reactive power detected by the detection meter 100, and then it can be determined whether the capacitance value of the capacitor unit is normal.
[0049] The reactive power compensation device provided in this application embodiment utilizes a detection meter and a controller to detect whether the capacitance value of a connected capacitor unit is normal when only one capacitor unit is connected to the AC bus. The hardware is simple and the detection method is easy to implement. When an abnormality occurs in a capacitor unit, an alarm is triggered promptly, causing the abnormal capacitor unit to stop working and ensuring the accuracy of reactive power compensation. This application embodiment does not specifically limit the voltage level of the AC bus. For ease of understanding, the application scenario of the reactive power compensation device also includes inverters, with the inverter connected to the AC bus as an example for description.
[0050] See Figure 2 The figure is a schematic diagram of another reactive power compensation device provided in the embodiments of this application.
[0051] This application embodiment uses an AC bus connected to the AC side of the inverter 2000 as an example for explanation. This application embodiment does not specifically limit the timing of the controller's detection of the capacitor unit; it can be performed before or during inverter 2000 operation. Furthermore, during inverter 2000 operation, the controller can perform detection when the reactive power compensation equipment is working or when the reactive power compensation equipment is not working.
[0052] Due to its limited driving capability, the controller 200 requires an I / O module 300 to control the switching on and off of the capacitor cells. The I / O module 300 connects to all capacitor cells and is also connected to the detection meter 100. Specifically, the controller 200 sends a switch-on or switch-off command to the I / O module 300, which then controls the capacitor cells to switch on or off accordingly. Furthermore, the controller 200 uses the I / O module 300 to read the reactive power of the detection meter 100 and the switch-on or switch-off status of the capacitor cells.
[0053] The reactive power compensation device provided in this application embodiment can perform periodic inspections of capacitor units. For example, an inspection cycle can be set, without specifically limiting the time of the inspection cycle. The inspection cycle can be set to 1 hour, 1 week, or 1 month, etc. The timed inspection period refers to the inspection time included in each inspection cycle. For example, it can be set to inspect once every hour, once a week, or once a month, etc. When the inspection cycle is reached, the controller will automatically inspect multiple capacitor units separately.
[0054] Specifically, the controller is configured to, upon arrival at the scheduled inspection time, disconnect all connected capacitor units from a plurality of capacitor banks, i.e., disconnect all capacitor banks. Each capacitor bank is then sequentially connected to the AC bus, one at a time. Each time a capacitor bank is connected, the capacitance value of the connected capacitor bank is determined based on the reactive power measured by the monitoring meter. In one scenario, some capacitor banks may be connected for reactive power compensation before the controller's inspection. During the inspection, each capacitor bank needs to be tested individually; therefore, it is necessary to first disconnect all connected capacitor banks. For example, if there are 10 sets of capacitor banks, and 3 sets are currently connected, before the inspection, these 3 connected sets need to be disconnected, and then the remaining 10 sets need to be connected sequentially for testing.
[0055] To facilitate traversing all capacitor cells during inspection, each capacitor cell in a multi-cell system is numbered, for example, pre-numbered to ensure each cell has a unique identifier. The controller is configured to arrive at the scheduled inspection time and control only one capacitor cell connection at a time, according to its assigned number. After the inspection is completed, the controller can release the normal capacitor cells, which can then participate in reactive power compensation.
[0056] The detection described above relies on a timed cycle for inspection. The following describes how the detection process can be triggered when the timed inspection time has not arrived, or when there is no timed inspection time (i.e., no timed inspection). If only one capacitor unit is detected to be connected, the detection process can also be triggered.
[0057] Specifically, the controller is configured to detect whether only one capacitor bank is currently connected to the AC bus during reactive power compensation when the scheduled inspection time has not arrived or when there is no scheduled inspection. When only one capacitor bank is currently connected to the AC bus, the controller determines whether the capacitance value of the currently connected capacitor bank is normal based on the reactive power detected by the power meter. Since only one capacitor bank is performing reactive power compensation at this time, there is no need to control the connected capacitor bank to switch off and on again. The capacitance value of the capacitor bank can be directly obtained from the reactive power detected by the power meter, which is simpler and more efficient.
[0058] Because the capacitors in the capacitor cell undergo a charging and discharging process during operation, to ensure more accurate capacitance readings, the reactive power detected by the meter can be read multiple times, using a method similar to the median to obtain the capacitance value. Specifically, the controller is configured to read the reactive power detected by the meter N times. When N is an odd number greater than or equal to 3, the middle reactive power value after sorting the N reactive power values is used to determine whether the capacitance value corresponding to the capacitor cell is normal. When N is an even number greater than 3, the two middle reactive power values after sorting the N reactive power values are used to determine whether the capacitance value corresponding to the capacitor cell is normal.
[0059] For example, in the simplest way, reactive power is read once in each of the three reading cycles. The three reactive power values are then sorted by size, and the median value is taken as the final reactive power value to obtain the capacitance value. When N is an even number, such as 4, after sorting the four reactive power values, the capacitance value can be obtained using the second reactive power value, the third reactive power value, or the average of the second and third reactive power values. To speed up the detection process, N can be chosen to be 3, which ensures both the speed and accuracy of the inspection.
[0060] Another possible implementation is that the controller is configured to read the reactive power detected by the meter N times, where N is an integer greater than or equal to 2. Based on the average of the N reactive power readings, the controller determines whether the capacitance value corresponding to the capacitor unit is normal. For example, if the average of the N reactive power readings is less than the preset capacitance value, then the capacitor unit is considered abnormal.
[0061] Another possible implementation involves configuring the controller to read the reactive power detected by the meter N times, where N is an integer greater than or equal to 2. Each of the N reactive power values is compared to a threshold, and the capacitance value of the corresponding capacitor unit is determined based on the comparison results. For example, if more than N / 2 of the N reactive power values are less than the threshold, the capacitance value of that capacitor unit is considered abnormal. Similarly, if N is 3 and two reactive power values are less than the threshold, the capacitance value of that capacitor unit is considered abnormal.
[0062] The reactive power compensation device provided in this application does not limit the specific criteria for the controller to determine the abnormality of the capacitor unit. For example, the controller is configured to obtain the capacitance value of the capacitor unit based on the reactive power. When the capacitance value is less than or equal to half of the nominal capacitance value of the capacitor unit, the capacitor unit is determined to be abnormal. When the capacitance value is less than half of the nominal capacitance value, it indicates that the capacitor unit is severely worn and needs to be replaced.
[0063] The reactive power compensation device provided in this application embodiment, to avoid repeated detection of abnormal capacitor units, further configures the controller to set an abnormality flag for the capacitor unit when an abnormality is determined. The next time the capacitance value of a capacitor unit is checked, the capacitor unit with the abnormality flag is skipped directly. The abnormally flagged capacitor unit neither participates in reactive power compensation work, nor does it need to be controlled to be switched on or off, nor does it participate in the next scheduled inspection. When the abnormally flagged capacitor unit is replaced, the abnormality flag can be cleared.
[0064] Based on the reactive power compensation device provided in the above embodiments, this application also provides a method for detecting abnormal capacitance, which will be described in detail below with reference to the accompanying drawings.
[0065] See Figure 3 The figure is a flowchart of an abnormal capacitance detection method provided in an embodiment of this application.
[0066] The abnormal capacitance detection method provided in this application includes:
[0067] S301: Start.
[0068] S302: When only one capacitor unit is currently connected to the AC bus among multiple capacitor units, the capacitance value of the connected capacitor unit is determined based on the reactive power detected by the detection meter.
[0069] The first end of multiple capacitor units is connected to the first end of the detection meter, and the second end of the detection meter is used to connect to the AC bus.
[0070] The embodiments of this application do not specifically limit the timing of capacitor unit detection; it can be performed before or during inverter operation. Furthermore, during inverter operation, the controller can perform detection when the capacitor unit is active or when it is deactivated.
[0071] The abnormal capacitor detection method provided in this application embodiment utilizes a testing meter to detect whether the capacitance value of a connected capacitor unit is normal when only one capacitor unit is connected. The hardware is simple and the detection method is easy to implement. When an abnormality occurs in a capacitor unit, an alarm is triggered promptly, causing the abnormal capacitor unit to stop working and ensuring the accuracy of reactive power compensation.
[0072] The abnormal capacitor detection method provided in this application does not limit the specific criteria for the controller to determine whether the capacitor unit is abnormal. For example, it can determine whether the capacitance value of the connected capacitor unit is normal based on the reactive power detected by the detection meter, including: obtaining the capacitance value corresponding to the capacitor unit based on the reactive power; when the capacitance value is less than or equal to half of the nominal capacitance value of the capacitor unit, the capacitor unit is determined to be abnormal. When the capacitance value is lower than half of the nominal capacitance value, it indicates that the capacitor unit is severely worn and needs to be replaced.
[0073] See Figure 4 The figure is a flowchart of another abnormal capacitance detection method provided in an embodiment of this application.
[0074] The abnormal capacitance detection method provided in this application includes:
[0075] S401: Check if the scheduled inspection time has arrived. If yes, execute S402; otherwise, wait.
[0076] S402: When the scheduled inspection time arrives, all capacitor units connected to the AC bus are switched off, and each capacitor unit in the control system is sequentially connected to the AC bus. The purpose is to ensure that only one capacitor unit is currently connected to the AC bus.
[0077] Controlling each capacitor unit in a plurality of capacitor units to connect to the AC bus in sequence includes: controlling only one capacitor unit to connect to the AC bus at a time according to the number of each capacitor unit in the plurality of capacitor units.
[0078] S403: When each capacitor unit is connected, read the reactive power detected by the detection meter N times. When N is an odd number greater than or equal to 3, determine whether the capacitance value corresponding to the capacitor unit is normal based on the middle reactive power after sorting the N reactive power values. When N is an even number greater than 3, determine whether the capacitance value corresponding to the capacitor unit is normal based on the two middle reactive power values after sorting the N reactive power values.
[0079] S404: When the capacitance value is less than or equal to half of the nominal capacitance value of the capacitor cell, the capacitor cell is determined to be faulty.
[0080] S405: When a capacitor cell is determined to be abnormal, an abnormality flag is set for the capacitor cell. The next time the capacitance value of a capacitor cell is checked, the capacitor cell with the abnormality flag is skipped directly.
[0081] S406: Cycle through S403 to S405 until all capacitor cells have been traversed.
[0082] The specific judgment method for S403 can also include the following two, for example:
[0083] The first method involves reading the reactive power detected by the testing meter N times, where N is an integer greater than or equal to 2. Based on the average of the N reactive power readings, the capacitance value corresponding to the capacitor unit is determined to be normal. For example, if the average of the N reactive power readings is less than a preset capacitance value, then the capacitor unit is considered abnormal.
[0084] The second method involves reading the reactive power detected by the testing meter N times, where N is an integer greater than or equal to 2. Each of the N reactive power readings is compared to a threshold value. Based on the comparison results, it is determined whether the capacitance value corresponding to the capacitor unit is normal. For example, if N is 3 and two reactive power readings are less than the threshold, then the capacitor unit is considered abnormal.
[0085] The detection described above relies on a timed cycle for inspection. The following describes how the detection process can be triggered when only one capacitor unit is detected to be connected, even if the timed inspection time has not arrived or there is no timed inspection time (i.e., no timed inspection).
[0086] Specifically, it also includes: during the reactive power compensation process when the scheduled inspection time has not arrived or there is no scheduled inspection, detecting whether only one capacitor unit is currently connected to the AC bus. When it is detected that only one capacitor unit is currently connected to the AC bus, judging whether the capacitance value of the currently connected capacitor unit is normal based on the reactive power detected by the detection meter.
[0087] Based on the reactive power compensation device and abnormal capacitor detection method provided in the above embodiments, this application also provides a photovoltaic system, which will be described in detail below with reference to the accompanying drawings.
[0088] See Figure 5 The figure is a schematic diagram of a photovoltaic system provided in an embodiment of this application.
[0089] The photovoltaic system provided in this application includes the reactive power compensation device 1000 described in the above embodiments, and also includes an inverter 2000;
[0090] The reactive power compensation device 1000 is connected to the AC side of the inverter.
[0091] This application does not specifically limit the application scenario of the reactive power compensation equipment, and it can be applied to distributed photovoltaic systems, such as industrial and commercial photovoltaic systems, specifically rooftop photovoltaic systems for factories. Because the photovoltaic system provided in this application can accurately detect whether the capacitor units are functioning properly and promptly alarm and replace them when problems occur, it can ensure more reliable reactive power compensation in the photovoltaic system and improve the quality of power supply.
[0092] In one possible implementation, see Figure 6 The figure is a schematic diagram of a control device provided in an embodiment of this application.
[0093] The control device may include a memory 1011 and a processor 1012. The processor 1012 can be connected to the reactive power compensation device and can control the switching on or off of each capacitor unit in the reactive power compensation device. Figure 6As shown, the memory can be random access memory (RAM), flash memory, read-only memory (ROM), EPROM, non-volatile read-only memory (Electronic Programmable ROM), registers, hard disks, removable disks, etc.
[0094] The memory 1011 can store computer instructions. When the computer instructions stored in the memory 1011 are executed by the processor 1012, the processor 1012 can be used to execute the method. The memory 1011 can also store data, such as information like the nominal capacitance value involved in the above embodiments.
[0095] In the above embodiments, implementation can be achieved, in whole or in part, through software, hardware, firmware, or any combination thereof. When implemented in software, it can be implemented, in whole or in part, as a computer program product. A computer program product includes one or more computer instructions. When the computer program instructions are loaded and executed on a computer, all or part of the flow or function according to the embodiments of this application is generated. The computer can be a general-purpose computer, a special-purpose computer, a computer network, or other programmable device. The computer instructions can be stored in a computer-readable storage medium or transmitted from one computer-readable storage medium to another. For example, computer instructions can be transmitted from one website, computer, server, or data center to another website, computer, server, or data center via wired (e.g., coaxial cable, fiber optic, digital subscriber line (DSL)) or wireless (e.g., infrared, wireless, microwave, etc.) means. The computer-readable storage medium can be any available medium that a computer can access or a data storage device such as a server or data center that integrates one or more available media. The available medium can be a magnetic medium (e.g., floppy disk, hard disk, magnetic tape) or a semiconductor medium (e.g., solid-state disk (SSD)).
[0096] This application also provides a readable storage medium for storing the methods provided in the above embodiments. Examples include random access memory (RAM), flash memory, read-only memory (ROM), EPROM, non-volatile read-only memory (EPROM), registers, hard disks, removable disks, or any other form of storage medium in the art.
[0097] It should be noted that the various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. The same or similar parts between the various embodiments can be referred to each other.
[0098] The above description of the disclosed embodiments enables those skilled in the art to make or use this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.
Claims
1. A reactive power compensation device, characterized in that, include: Controller, detection meter and multiple capacitor units; The first end of each of the plurality of capacitor units is connected to the first end of the detection meter, and the second end of the detection meter is used to connect to the AC bus. The controller is configured to determine whether the capacitance value of the connected capacitor unit is normal based on the reactive power detected by the detection meter when only one capacitor unit among the plurality of capacitor units is currently connected to the AC bus.
2. The reactive power compensation device according to claim 1, characterized in that, The controller is also configured to, upon arrival at the scheduled inspection time, control all connected capacitor units among the plurality of capacitor units to be switched off, and then control each capacitor unit among the plurality of capacitor units to be sequentially connected to the AC bus, so that only one capacitor unit is currently connected to the AC bus.
3. The reactive power compensation device according to claim 1, characterized in that, The controller is also configured to detect whether only one capacitor unit is currently connected to the AC bus during the reactive power compensation process of the reactive power compensation device.
4. The reactive power compensation device according to any one of claims 1-3, characterized in that, The controller is configured to read the reactive power detected by the detection meter N times. When N is an odd number greater than or equal to 3, the controller determines whether the capacitance value of the capacitor unit is normal based on the middle reactive power value after sorting the N reactive power values. When N is an even number greater than 3, the controller determines whether the capacitance value of the capacitor unit is normal based on the two middle reactive power values after sorting the N reactive power values. or, The controller is configured to read the reactive power detected by the detection meter N times, where N is an integer greater than or equal to 2, and determine whether the capacitance value of the capacitor unit is normal based on the average value of the N reactive power readings. or, The controller is configured to read the reactive power detected by the detection meter N times, where N is an integer greater than or equal to 2, compare the N reactive power values with a threshold, and determine whether the capacitance value of the capacitor unit is normal based on the comparison results.
5. The reactive power compensation device according to any one of claims 1-3, characterized in that, The controller is configured to obtain the capacitance value of the capacitor unit based on the reactive power, and to determine that the capacitor unit is abnormal when the capacitance value is less than or equal to half of the nominal capacitance value of the capacitor unit.
6. The reactive power compensation device according to any one of claims 1-3, characterized in that, The controller is also configured to set an abnormality flag for the capacitor unit when it is determined that the capacitor unit is abnormal, and to skip the capacitor unit with the abnormality flag when checking whether the capacitance value of the capacitor unit is normal the next time.
7. The reactive power compensation device according to claim 2, characterized in that, Each of the plurality of said capacitor units has a number; The controller is used to arrive at the scheduled inspection time and control only one capacitor unit to connect to the AC bus at a time according to the number.
8. A method for detecting abnormal capacitance, characterized in that, include: When only one capacitor unit among multiple capacitor units is currently connected to the AC bus, the capacitance value of the connected capacitor unit is determined based on the reactive power detected by the detection meter. The first end of the multiple capacitor units is connected to the first end of the detection meter, and the second end of the detection meter is used to connect to the AC bus.
9. The method according to claim 8, characterized in that, The detection method further includes: When the scheduled inspection time arrives, all the connected capacitors in the multiple capacitor units are switched off, and then each capacitor unit in the multiple capacitor units is sequentially connected to the AC bus, so that only one capacitor unit is currently connected to the AC bus.
10. The method according to claim 8, characterized in that, The detection method further includes: during the reactive power compensation process through multiple capacitor units, detecting whether only one capacitor unit is currently connected to the AC bus.
11. The method according to any one of claims 8-10, characterized in that, Determining whether the capacitance value of the connected capacitor unit is normal based on the reactive power detected by the power meter includes: Read the reactive power detected by the meter N times; When N is an odd number greater than or equal to 3, the capacitance value of the capacitor unit is determined to be normal based on the reactive power value that is in the middle after sorting the N reactive power values. When N is an even number greater than 3, the capacitance value of the capacitor unit is determined to be normal based on the two middle reactive power values after sorting the N reactive power values. or, Read the reactive power detected by the detection meter N times, and determine whether the capacitance value of the capacitor unit is normal based on the average value of the N reactive power values, where N is an integer greater than or equal to 2; or, The reactive power detected by the detection meter is read N times, and the N reactive power values are compared with the threshold value respectively. Based on the comparison results, it is determined whether the capacitance value of the capacitor unit is normal. N is an integer greater than or equal to 2.
12. The method according to any one of claims 8-10, characterized in that, Determining whether the capacitance value of the connected capacitor unit is normal based on the reactive power detected by the power meter includes: The capacitance value of the capacitor unit is obtained based on the reactive power. When the capacitance value is less than or equal to half of the nominal capacitance value of the capacitor cell, the capacitor cell is determined to be faulty.
13. The method according to any one of claims 8-10, characterized in that, The detection method further includes: When a capacitor cell is determined to be abnormal, an abnormality flag is set for the capacitor cell. The next time the capacitance value of a capacitor cell is checked, the capacitor cell with the abnormality flag is skipped directly.
14. The method according to claim 9, characterized in that, Controlling each of the plurality of capacitor units to be sequentially connected to the AC bus includes: According to the number of each capacitor unit in the plurality of capacitor units, only one capacitor unit is controlled to be connected to the AC bus at a time.
15. A photovoltaic system, characterized in that, The device includes the reactive power compensation equipment as described in any one of claims 1-7, and also includes an inverter; The reactive power compensation device is connected to the AC side of the inverter.