Reactive compensation and harmonic suppression system

Abstract

The utility model relates to a reactive compensation and harmonic suppression system which comprises an outgoing line bar, a low-voltage incoming line cabinet, a transformer, an active filter and a reactive compensation device. The input end of the outgoing line bar is suitable for being connected with the output end of a power grid, the output end of the outgoing line bar is electrically connected with the input end of the load equipment, the outgoing line bar is bidirectionally and electrically connected with the low-voltage incoming line cabinet, and the low-voltage incoming line cabinet is bidirectionally and electrically connected with the active filter and the reactive power compensation device; the outgoing line bar is electrically connected with the input end of the transformer, and the output end of the transformer outputs transformed voltage through the busbar; the active filtering and reactive power compensation device comprises a main compensation device; the main compensation device comprises more than two power modules, and any power module comprises a compensation capacitor; the compensation capacitor is bidirectionally and electrically connected with the low-voltage wire inlet cabinet and is suitable for accessing current output by a power grid to carry out harmonic suppression on the current, reactive power is transmitted to the power grid through the low-voltage wire inlet cabinet, and the power factor of the power grid is improved by carrying out harmonic suppression and reactive compensation on the current.

Description

Technical Field

[0001] This application relates to the field of power supply technology for oil drilling power grids, and in particular to a reactive power compensation and harmonic suppression system. Background Technology

[0002] With the continuous economic growth and rapid development of the oil drilling industry, the demand for electricity has increased dramatically, making the stable and efficient operation of the power system crucial. Currently, the electrical equipment used in drilling (such as motors, transformers, and frequency converters) is often powered directly from the power grid. However, most of these electrical devices are inductive and nonlinear loads. During operation, due to their inductive or nonlinear characteristics, the current often lags behind the voltage, resulting in reactive power. The increase in reactive power not only leads to a decrease in the power factor of the power grid, increases transmission losses, and reduces the transmission efficiency of the power grid, but may also affect the normal operation of other equipment. Summary of the Invention

[0003] In view of this, this application proposes a reactive power compensation and harmonic suppression system, including: outgoing line bus, low-voltage incoming line cabinet, transformer, active filter and reactive power compensation device;

[0004] The input end of the outgoing line busbar is suitable for connecting to the output end of the power grid. The output end of the outgoing line busbar is electrically connected to the input end of the load equipment. The outgoing line busbar is also bidirectionally electrically connected to the low-voltage incoming line cabinet. The low-voltage incoming line cabinet is bidirectionally electrically connected to the active filter and reactive power compensation device.

[0005] The output busbar is electrically connected to the input terminal of the transformer, and the output terminal of the transformer outputs the transformed voltage through the busbar;

[0006] The active filtering and reactive power compensation device includes a main compensation device; the main compensation device includes two or more power modules, each of which includes a compensation capacitor; the compensation capacitor is bidirectionally electrically connected to the low-voltage incoming cabinet to accept the current output from the power grid to suppress harmonics in the current, and to transmit reactive power to the power grid through the low-voltage incoming cabinet.

[0007] In one possible implementation, the low-voltage incoming switchgear includes a first frame circuit breaker; the outgoing line busbar is electrically connected to an active filter and reactive power compensation device via the first frame circuit breaker.

[0008] In one possible implementation, the low-voltage incoming switchgear also includes a voltage sampling device; the voltage sampling device is electrically connected to the circuit between the first frame circuit breaker and the outgoing line bar.

[0009] In one possible implementation, the power module also includes: a second frame circuit breaker; the low-voltage incoming cabinet is electrically connected to the compensation capacitor via the second frame circuit breaker.

[0010] In a possible implementation, the current transformer is further configured to: receive the current from the power grid; and transmit the current to the active power filter and reactive power compensation device.

[0011] In a possible implementation, the current transformer is arranged on the power supply side of the active power filter and reactive power compensation device.

[0012] In a possible implementation, the current transformer is arranged on the load side of the active power filter and reactive power compensation device.

[0013] In a possible implementation, the active power filter and reactive power compensation device further comprises two or more slave compensation devices, and each of the two or more slave compensation devices comprises two or more power modules.

[0014] In a possible implementation, the active power filter and reactive power compensation device comprises three slave compensation devices.

[0015] Advantages

[0016] The current in the power grid flows to the low-voltage incoming line cabinet through the outgoing line, the outgoing line transmits the current transmitted by the power grid to the active power filter and reactive power compensation device through the low-voltage incoming line cabinet, and the harmonic is mainly caused by the phase difference between the current and the voltage. Since the compensation capacitor leads the current phase in the circuit ahead of the voltage phase, the leading current of the compensation capacitor interacts with the lagging current generated by the device at the load end to reduce the phase difference, thereby achieving suppression of the harmonic in the current and reducing the harmonic content in the current. At the same time, the compensation capacitor can absorb or release reactive power according to its own characteristics. When the reactive power in the power system is excessive, the compensation capacitor absorbs the reactive power and stores the reactive power, thereby reducing the reactive power in the power grid. On the contrary, when the reactive power in the power system is insufficient, the compensation capacitor releases the reactive power, thereby increasing the reactive power in the power grid, thereby adjusting the power factor of the power grid.

[0017] The application sets the active power filter and reactive power compensation device, which receives the current output by the power grid, suppresses the harmonic of the current through the capacitive characteristics of the active power filter and reactive power compensation device, absorbs the reactive power in the power grid according to the reactive power demand of the power grid, or transmits the absorbed reactive power to the power grid through the low-voltage incoming line cabinet, effectively improves the power quality of the power grid, reduces the interference and damage of the harmonic to the load end device, prolongs the service life of the load end device, improves the power factor of the power grid, reduces the transmission of the reactive power in the power grid, reduces the line loss, ensures the normal operation of the load end device, improves the transmission efficiency of the power grid, and reduces the electricity cost.

[0018] Other features and aspects of the present application will become apparent from a detailed description of exemplary embodiments with reference to the following drawings. BRIEF DESCRIPTION OF DRAWINGS

[0019] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate exemplary embodiments, features, and aspects of the application and serve to explain the principles of the application.

[0020] Figure 1 A main circuit diagram of a reactive power compensation and harmonic suppression system of the present application is shown;

[0021] Figure 2 An internal circuit diagram of a low-voltage incoming line cabinet of the present application is shown;

[0022] Figure 3 An internal circuit diagram of an electric control room of the present application is shown;

[0023] Figure 4 A structure schematic diagram of a current transformer of the present application arranged at a power supply side is shown;

[0024] Figure 5 A structure schematic diagram of a current transformer of the present application arranged at a load side is shown. DETAILED DESCRIPTION

[0025] Various exemplary embodiments, features, and aspects of the present application will be described in detail below with reference to the accompanying drawings. The same reference numbers in the drawings indicate functionally similar or identical elements. Although various aspects of the embodiments are shown in the drawings, the drawings are not necessarily drawn to scale unless specifically indicated.

[0026] It should be understood that the terms "center", "longitudinal", "transverse", "length", "width", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application or simplifying the description, and therefore cannot be understood as indicating or implying that the devices or elements indicated must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the present application.

[0027] In addition, the terms "first", "second", "third", etc. are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the technical features indicated. Therefore, the features defined with "first", "second", etc. can explicitly or implicitly include one or more of the features. In the description of the present application, the meaning of "multiple" is two or more, unless otherwise specifically limited.

[0028] The word "exemplary" is used herein to mean "serving as an example, instance, or illustration." Any implementation described herein as "exemplary" is not necessarily to be construed as preferred or advantageous over other implementations.

[0029] In addition, for the purpose of convenience and brevity, detailed descriptions of well-known devices and methods are omitted so as not to obscure the concepts of the application. It is to be understood that the terminology used herein is for the purpose of describing specific embodiments only and is not intended to be limiting.

[0030] Figure 1 The main circuit diagram of the reactive power compensation and harmonic suppression system of the application is shown; the application proposes a reactive power compensation and harmonic suppression system, as shown in Figures 1 to 5 The output end of the outgoing line row 430 is electrically connected with the input end of the load device, and the outgoing line row 430 and the low-voltage incoming line cabinet 100 are bidirectionally electrically connected, the low-voltage incoming line cabinet 100 and the active power filter and reactive power compensation device 200 are bidirectionally electrically connected; the outgoing line row 430 is electrically connected with the input end of the transformer 510, and the output end of the transformer 510 outputs the voltage after transformation through the busbar 520; the active power filter and reactive power compensation device 200 comprises a main compensation device 210; the main compensation device 210 comprises two or more power modules, and any power module comprises: a compensation capacitor 211; the compensation capacitor 211 is bidirectionally electrically connected with the low-voltage incoming line cabinet 100 and is adapted to access the current output by the power grid 410 to suppress the harmonic of the current, and to deliver the reactive power to the power grid 410 through the low-voltage incoming line cabinet 100.

[0031] It should be noted here that the outgoing line row 430 is suitable for providing power input for the whole system, the outgoing line row 430 distributes the power of the power grid 410, the low-voltage incoming line cabinet 100 is suitable for controlling the opening and closing of the active filter and reactive power compensation device 200, the low-voltage incoming line cabinet 100 transmits the power transmitted by the outgoing line row 430 to the active filter and reactive power compensation device 200, and provides current for the active filter and reactive power compensation device 200; After the active filter and reactive power compensation device 200 accesses the current output by the power grid 410, the current is suppressed by the capacitive characteristic of the active filter and reactive power compensation device 200, thereby reducing the harmonic content, at the same time, the compensation capacitor 211 can generate capacitive reactive power, which is transmitted to the power grid 410 through the low-voltage incoming line cabinet 100, thereby realizing the adjustment of the power factor of the power grid 410, the transformer 510 converts the 600V high voltage into 400V low voltage to provide appropriate voltage power for the equipment in the electric control room 530, and the busbar 520 effectively transmits the voltage output by the transformer 510 to the electric control room 530, thereby providing stable power supply for the equipment in the electric control room 530, and ensuring the normal operation of the equipment in the electric control room 530.

[0032] The current in the power grid 410 flows to the low-voltage incoming line cabinet 100 through the outgoing line row 430, the outgoing line row 430 transmits the current transmitted by the power grid 410 to the active filter and reactive power compensation device 200 through the low-voltage incoming line cabinet 100, the harmonic is mainly caused by the phase difference between the current and the voltage, since the compensation capacitor 211 leads the current phase in the circuit to the voltage phase, the leading current of the compensation capacitor 211 interacts with the lagging current generated by the equipment at the load end 420 to reduce the phase difference, thereby realizing the suppression of the harmonic in the current and reducing the harmonic content in the current, at the same time, the compensation capacitor can absorb or release reactive power according to its own characteristics, when the reactive power in the power system is too much, the compensation capacitor 211 will absorb the reactive power and store the reactive power, thereby reducing the reactive power in the power grid 410, on the contrary, when the reactive power in the power system is insufficient, the compensation capacitor 211 will release the reactive power, thereby increasing the reactive power in the power grid 410, thereby adjusting the power factor of the power grid 410.

[0033] The application sets the active filter and reactive power compensation device 200, which receives the current output by the power grid 410, and suppresses the current through its capacitive characteristics, and absorbs the reactive power in the power grid 410 or delivers the absorbed reactive power to the power grid 410 through the low-voltage incoming line cabinet 100 according to the reactive demand of the power grid 410, effectively improving the power quality of the power grid 410, reducing the interference and damage of harmonics to the load end 420 equipment, prolonging the service life of the load end 420 equipment. The power factor of the power grid 410 is improved, the transmission of reactive power in the power grid 410 is reduced, the line loss is reduced, the normal operation of the load end 420 equipment is ensured, the transmission efficiency of the power grid 410 is improved, and the power cost is reduced.

[0034] Further, the transformer 510 adopts a 600V / 400V-100kVA transformer 510 in the prior art; as shown in the figure, the primary winding of the transformer 510 is connected to a 600V voltage, and the secondary winding of the transformer 510 is adapted to be electrically connected to other electrical equipment to output a 220V voltage to other electrical equipment in the electrical control room 530, such as wall socket, lighting, sound and light alarm, smoke alarm, air conditioner host; the transformer 510 can provide AC 220V working power supply for these devices. Figure 3

[0035] At the same time, the secondary winding of the transformer 510 is electrically connected to the power supply end of the compensation capacitor 211, thereby providing AC 220V working power supply for the compensation capacitor 211.

[0036] In one possible implementation, the compensation capacitor 211 adopts a capacitor compensation cabinet with a model of SVG600-600V-300Kvar300kvar in the prior art.

[0037] In one possible implementation, as shown in the figure, Figure 2 ​As shown, the low-voltage incoming line cabinet 100 includes a first frame circuit breaker 110; the outgoing line row 430 is electrically connected with the active filter and reactive power compensation device 200 through the first frame circuit breaker 110; it should be noted that the first frame circuit breaker 110 is suitable for manually turning on and off the circuit in the low-voltage incoming line cabinet 100 to realize the active filter and reactive power compensation device 200 to be put into operation or withdrawn from operation; when it is needed to put the active filter and reactive power compensation device into use, the first frame circuit breaker 110 is closed to form a passage, and the current transmitted by the outgoing line row 430 is transmitted to the active filter and reactive power compensation device 200 through the low-voltage incoming line cabinet 100; the active filter and reactive power compensation device 200 performs reactive power compensation and harmonic suppression on the current flowing in; on the contrary, when the first frame circuit breaker 110 is closed, the circuit is open, and the active filter and reactive power compensation device 200 is not put into use; by setting the first frame circuit breaker 110, the active filter and reactive power compensation device 200 can be controlled to be put into and withdrawn from operation, and at the same time, when the active filter and reactive power compensation device 200 needs to be maintained and overhauled, the operator can conveniently cut off the power supply of the device by operating the first frame circuit breaker 110, so that the maintenance work can be safely carried out.

[0038] Further, as shown in Figure 2 The low-voltage incoming line cabinet 100 further includes an under-voltage coil 120, which is electrically connected to the circuit between the first frame circuit breaker 110 and the outgoing line row 430; the under-voltage coil 120 is suitable for ensuring that the first frame circuit breaker 110 can be closed only when the power supply voltage meets the preset threshold; when the voltage transmitted by the outgoing line row 430 to the under-voltage coil 120 meets the preset threshold, the voltage is in a normal state, the under-voltage coil 120 is powered, and at this time the first frame circuit breaker 110 can be manually closed; when the power supply voltage is lower than the preset threshold or the first frame circuit breaker 110 is manually opened, the under-voltage coil 120 is powered off, and at this time the first frame circuit breaker 110 is in an open state, and the active filter and reactive power compensation device 200 is withdrawn from operation, so as to prevent the active filter and reactive power compensation device 200 from being operated or damaged under low voltage.

[0039] The preset threshold of the voltage can be set according to the actual operation scene, and in the embodiment, the preset threshold of the voltage is 600V.

[0040] In a possible implementation manner, as shown in Figure 2As shown in the figure, the low-voltage incoming line cabinet 100 further comprises an indicator lamp 140, which is electrically connected with the first frame circuit breaker 110, and is adapted to display the on and off states of the first frame circuit breaker 110. When the first frame circuit breaker 110 is on, the circuit in which the indicator lamp 140 is located is in a conducting state, and the indicator lamp 140 is on, thereby indicating that the first frame circuit breaker 110 is in an on state. When the first frame circuit breaker 110 is off, the circuit in which the indicator lamp 140 is located is in a non-conducting state, and the indicator lamp 140 is off.

[0041] In a possible implementation manner, as shown in the figure, Figure 2 As shown in the figure, the low-voltage incoming line cabinet 100 further comprises a voltage sampling device 130, which is electrically connected to the circuit between the first frame circuit breaker 110 and the outgoing line row 430. By arranging the voltage sampling device 130, the staff can intuitively obtain whether the voltage flowing into the low-voltage incoming line cabinet 100 meets the voltage requirement of the active power filter and reactive power compensation device 200.

[0042] Further, the voltage sampling device 130 adopts a voltage sampling meter with a model number of 45L9-V, 600V / 100V, 50Hz (scale: 0-750V) in the prior art.

[0043] Preferably, the low-voltage incoming line cabinet 100 adopts a GCS low-voltage cabinet with a model number of CND-G-A40 in the prior art.

[0044] In a possible implementation manner, as shown in the figure, Figure 1 As shown in the figure, the power module further comprises a second frame circuit breaker 222, and the low-voltage incoming line cabinet 100 is electrically connected with the compensation capacitor 211 through the second frame circuit breaker 222. It should be noted that the staff can control the on and off of the second frame circuit breaker 222 according to the demand of the power grid 410, so as to realize the connection and disconnection of the circuit between the compensation capacitor 211 and the low-voltage incoming line cabinet 100, and further control the operation of the compensation capacitor 211. At the same time, the second frame circuit breaker 222 can prevent the compensation capacitor 211 from being damaged due to overload or short circuit, prolong the service life of the capacitor compensator, and reduce the maintenance and replacement cost of the equipment.

[0045] In a possible implementation manner, as shown in the figure, Figure 4 , Figure 5 As shown in the figure, the power module further comprises a current transformer 300, an input end of the current transformer 300 is electrically connected with the power grid 410, and is adapted to collect the current value in the power grid 410. An output end of the current transformer 300 is electrically connected with the active power filter and reactive power compensation device 200, and is adapted to transmit the collected signal to the active power filter and reactive power compensation device 200.

[0046] It should be noted that the active filter and reactive power compensation device 200 is provided with a CT conversion board and a main control board in the main compensation device 210, the CT conversion board is electrically connected with the main control board, the current transformer 300 is electrically connected with the CT conversion board in the main compensation device 210, the current transformer 300 is suitable for monitoring the current change of the power grid 410 in real time, and provides a basis for the active filter and reactive power compensation device 200 to adjust the output of the reactive power in real time, the current transformer 300 monitors the current change of the power grid 410 in real time by using the electromagnetic induction principle, and transmits the data to the CT conversion board in the active filter and reactive power compensation device 200, the CT conversion board processes and converts the data transmitted by the current transformer 300 and then transmits the data to the main control board, the main control board in the active filter and reactive power compensation device 200 receives the data converted by the CT conversion board, judges the size and direction of the reactive power required by the power grid 410 based on the received converted data, and controls the active filter and reactive power compensation device 200 to absorb or release the reactive power to meet the reactive power demand of the power grid 410 and suppress the harmonic, so that the harmonic content is controlled within the allowable range, the compensation and adjustment of the reactive power of the power grid 410 are realized, the power quality is improved, and the power factor of the power grid 410 is improved.

[0047] In a possible implementation manner, as shown in Figure 4 The current transformer 300 is arranged on the power supply side of the active filter and reactive power compensation device 200. It should be noted that the input end of the current transformer 300 is connected with the power grid 410, and the output end of the current transformer 300 is electrically connected with the input end of the active filter and reactive power compensation device 200. The current transformer 300 monitors the current flowing into the active filter and reactive power compensation device 200 in real time by using the electromagnetic induction principle, and outputs the data to the active filter and reactive power compensation device 200. The active filter and reactive power compensation device 200 needs to acquire the current information of the power supply side in real time, so as to judge the operation state of the power grid 410 and provide a data basis for subsequent reactive power compensation and harmonic suppression operations.

[0048] In a possible implementation manner, as shown in Figure 5 The current transformer 300 is arranged on the load side of the active filter and reactive power compensation device 200. It should be noted that the current transformer 300 can monitor the current change of the load side in real time, and the active filter and reactive power compensation device 200 dynamically adjusts the output according to the data measured by the load side current transformer 300, provides appropriate reactive power to the load, and effectively improves the power factor of the load.

[0049] Further, the current transformer 300 can be provided two, two current transformers 300 are provided on the power supply side and the load side of the active filter and reactive power compensation device 200, and the active filter and reactive power compensation device 200 compares and analyzes the current data detected by the load side current transformer 300 and the current data detected by the power supply side current transformer 300, so as to realize more accurate compensation control and improve the filtering and reactive power compensation effect.

[0050] Further, the current transformer 300 adopts a current transformer with a model of SDH-0.66, 0.2 level, 5000 / 5A, 30VA, 50Hz, 120x50 II type in the prior art.

[0051] In a possible implementation manner, as shown in Figure 1 The active filter and reactive power compensation device 200 further includes two or more slave compensation devices 220, and the two or more slave compensation devices 220 also include two or more power modules.

[0052] It should be noted that, as shown in Figure 2 Further, the busbar is electrically connected with the first frame circuit breaker 110, and the two or more slave compensation devices 220 and the master compensation device 210 are electrically connected with the busbar. The plurality of slave compensation devices 220 work cooperatively, and the slave compensation devices 220 compensate and suppress harmonics according to different load devices, thereby improving the processing efficiency of the active filter and reactive power compensation device 200. The structures and functions of the power modules in the slave compensation devices 220 and the master compensation device 210 are the same, and have been described in detail above, and thus will not be described here again.

[0053] Further, the master compensation device 210 is communicatively connected with the second frame circuit breaker 222 of the slave compensation device 220 through a master control board, and the master compensation device 210 controls the second frame circuit breaker 222 through the master control board, so as to control the output power of the slave compensation device 220. Specifically, when the power grid needs more reactive power compensation, the master control board sends a command to make the second frame circuit breaker 222 of the corresponding slave compensation device 220 close, so as to connect the compensation capacitor 211 to the circuit, thereby increasing the reactive power output of the slave compensation device 220. Conversely, when the reactive power compensation is excessive, the master control board can control the second frame circuit breaker 222 to open, thereby cutting off part of the compensation capacitor 211, so as to reduce the output power of the slave compensation device 220. The master compensation device 210 uniformly controls and manages the two or more slave compensation devices 220, adjusts the output power of each slave compensation device 220, and ensures that the active filter and reactive power compensation device 200 can effectively compensate reactive power and suppress harmonics, thereby maintaining the stable operation of the power system.

[0054] Preferably, the main control board uses the SVG600-U1 microcontroller, which is a model in the existing technology.

[0055] In one possible implementation, such as Figure 1 As shown, there are three slave compensation devices 220. It should be noted that the three slave compensation devices 220 form a redundancy mechanism. During system operation, the compensation task can be flexibly allocated to the three slave compensation devices 220 according to the reactive power demand and harmonic suppression status of the power grid 410, ensuring the stable operation of the power grid 410.

[0056] Furthermore, such as Figure 1 , Figure 2 Figure 2 As shown, two of the compensation devices 220 are equipped with three power modules, all of which are bidirectionally electrically connected to the low-voltage incoming cabinet 100. They are used to connect to the current output of the power grid 410 to suppress harmonics and to transmit reactive power to the power grid 410 through the low-voltage incoming cabinet 100. The other compensation device 220 is equipped with two power modules, both of which are bidirectionally electrically connected to the low-voltage incoming cabinet 100.

[0057] The various embodiments of this application have been described above. These descriptions are exemplary and not exhaustive, nor are they limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments. The terminology used herein is chosen to best explain the principles, practical application, or improvement of the technology in the market, or to enable others skilled in the art to understand the embodiments disclosed herein.

Claims

1. A reactive power compensation and harmonic suppression system, characterized in that, include: Outgoing line bar, low-voltage incoming line cabinet, transformer, active filter and reactive power compensation device; The input end of the outgoing line is suitable for connecting to the output end of the power grid. The output end of the outgoing line is electrically connected to the input end of the load equipment. The outgoing line is bidirectionally electrically connected to the low-voltage incoming line cabinet. The low-voltage incoming line cabinet is bidirectionally electrically connected to the active filter and reactive power compensation device. The output busbar is electrically connected to the input terminal of the transformer, and the output terminal of the transformer outputs the transformed voltage through the busbar; The active filtering and reactive power compensation device includes a main compensation device; the main compensation device includes two or more power modules, and each of the power modules includes a compensation capacitor; The compensation capacitor is bidirectionally electrically connected to the low-voltage incoming cabinet to receive the current output from the power grid for harmonic suppression, and to transmit reactive power to the power grid through the low-voltage incoming cabinet.

2. The reactive power compensation and harmonic suppression system according to claim 1, characterized in that, The low-voltage incoming switchgear includes a first frame circuit breaker; The outgoing line is electrically connected to the active filter and reactive power compensation device through the first frame circuit breaker.

3. The reactive power compensation and harmonic suppression system according to claim 2, characterized in that, The low-voltage incoming line cabinet also includes: a voltage sampling device; The voltage sampling device is electrically connected to the circuit between the first frame circuit breaker and the outgoing line.

4. The reactive power compensation and harmonic suppression system according to claim 1, characterized in that, The power module also includes: a second frame circuit breaker; The low-voltage incoming switchgear is electrically connected to the compensation capacitor via the second frame circuit breaker.

5. The reactive power compensation and harmonic suppression system according to claim 1, characterized in that, Also includes: Current transformer; The input terminal of the current transformer is electrically connected to the power grid and is suitable for collecting the current value in the power grid. The output terminal of the current transformer is electrically connected to the active filter and reactive power compensation device and is suitable for transmitting the collected signal to the active filter and reactive power compensation device.

6. The reactive power compensation and harmonic suppression system according to claim 5, characterized in that, The current transformer is located on the power supply side of the active filter and reactive power compensation device.

7. The reactive power compensation and harmonic suppression system according to claim 5, characterized in that, The current transformer is installed on the load side of the active filter and reactive power compensation device.

8. The reactive power compensation and harmonic suppression system according to claim 1, characterized in that, The active filtering and reactive power compensation device also includes two or more slave compensation devices; The two or more of the aforementioned compensation devices also include two or more of the aforementioned power modules.

9. The reactive power compensation and harmonic suppression system according to claim 8, characterized in that, There are three compensation devices in total.

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