Isolation switch series connection type direct current magnetic bias suppression system
By using a series disconnector DC bias suppression system, combined with an air gap, current transformer, and surge arrester, multiple operating states of the transformer neutral point can be switched. By using a resistive DC bias suppression device to adjust the resistance, the problem of excessive DC bias current is solved, protecting the transformer and the power system, reducing costs, and improving safety and flexibility.
Patent Information
- Application Number
- CN202520106654.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2025-01-16
- Publication Date
- 2026-01-06
- Estimated Expiration
- 2035-01-16
AI Technical Summary
DC bias current exceeding the transformer's tolerance range leads to core magnetic flux saturation, increasing losses, affecting power quality and transformer lifespan, and causing severe excitation current distortion, which is difficult to effectively manage with existing technologies.
A series disconnector DC bias suppression system is adopted, which connects multiple main transformer neutral points to the DC bias suppression device. Combined with air gaps, current transformers and surge arresters, it realizes the switching of multiple operating states of the transformer neutral point, and uses a resistive DC bias suppression device to adjust the resistance to suppress DC bias current.
It effectively reduces the DC current at the neutral point of the transformer to an acceptable range, protects the transformer and the power system for normal operation, reduces management costs, and improves operational safety and layout flexibility.
Smart Images
Figure CN223771774U_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The utility model relates to the technical field of power system, concretely refers to a disconnecting switch series type direct current magnetic bias suppression system. BACKGROUND
[0002] At present, a series of high-voltage projects have been built. When the direct current project is in the monopolar ground operation mode, there is a larger direct current through the grounding electrode into the ground, which causes the potential of the grounding electrode of the surrounding substation to change, and then forms a potential difference. The direct current will flow from the power transmission line through the ground to the transformer neutral point, causing the transformer to have a direct current component, thereby generating transformer direct current magnetic bias phenomenon.
[0003] If the direct current magnetic bias current exceeds the bearing range of the transformer, the transformer core magnetic flux will be sharply saturated, the magnetic flux leakage will be increased, the core loss and copper loss will be increased, the transformer will be overheated, the insulation will be damaged, and the service life of the transformer will be reduced or even the transformer will be damaged. At the same time, the direct current magnetic bias current will also cause serious distortion of the excitation current, generate a large amount of harmonics, affect the power quality, increase the reactive power loss of the power system, cause the vibration of the transformer operation to be enhanced, and the noise to be obviously increased.
[0004] Therefore, it is necessary to treat the transformer direct current magnetic bias current exceeding the standard, and solve the influence of the excessive direct current magnetic bias current on the transformer and the power system. Utility model content
[0005] In order to overcome the above technical defects, the utility model discloses a disconnecting switch series type direct current magnetic bias suppression system, solves the problem of direct current magnetic bias current exceeding the standard, suppresses the direct current magnetic bias current, protects the normal operation of the transformer and the power system, and has the advantages of low cost.
[0006] In order to achieve the above object, the utility model adopts the following technical scheme:
[0007] The application discloses a disconnector series type direct current biasing suppression system, which is characterized in that: a plurality of main transformers are connected to each other at neutral points and are connected to a same direct current biasing suppression device; the neutral points are neutral points of high-voltage windings or low-voltage windings of the main transformers; a first disconnector and a third disconnector are arranged in sequence between the neutral points and the direct current biasing suppression device, and the neutral points, the first disconnector, the third disconnector and the direct current biasing suppression device are connected in series; an air gap, a current transformer and a lightning arrester are arranged between the first disconnector and the neutral points of the main transformers, the air gap and the current transformer are connected in series and are connected in parallel with the lightning arrester, and the air gap and the lightning arrester are connected to the neutral points; one side of the third disconnector connected to the first disconnector is grounded. Through the wiring scheme, the neutral points of the transformers can be operated in three operating states of no grounding, direct grounding or grounding through a direct-current grounding device, and the mutual switching between the three operating states can be realized.
[0008] As a preferred scheme, the third disconnector is a single-grounding disconnector, which comprises a second disconnector and a grounding switch; the neutral points, the first disconnector and the second disconnector are connected in series with the direct current biasing suppression device; the grounding switch is arranged at one side of the second disconnector connected to the first disconnector; one end of the grounding switch is connected to the second disconnector, and the other end is grounded. The combined single-grounding disconnector can optimize the equipment support of the separately arranged grounding switch, and the combined equipment can be installed on the same equipment support.
[0009] As a preferred scheme, the first disconnector and the third disconnector and the second disconnector and the direct current biasing suppression device are connected through power cables. The arrangement of the second disconnector and the direct current biasing suppression device is flexible and is not limited by the site, and the connection has the advantages of high arrangement flexibility and high environmental adaptability.
[0010] As a preferred scheme, the static contact of the second disconnector is arranged at the side of the neutral points of the main transformers, and the dynamic contact is arranged at the side of the direct current biasing suppression device. The neutral points of the transformers are live sides, and the side of the direct current biasing suppression device is a grounded side; the dynamic contact is arranged at the grounded side, so that the potential of the dynamic contact is the ground potential when the dynamic contact is in action, and the safety of the closing and opening operation of the second disconnector can be effectively improved.
[0011] Further, the second disconnector is connected to the high-voltage side of the direct current biasing suppression device, and the low-voltage side of the direct current biasing suppression device is grounded. Through the connection of the first disconnector and the second disconnector and the connection of the second disconnector and the high-voltage side of the direct current biasing suppression device, the direct current biasing current on the transformer can be effectively introduced into the direct current biasing suppression device for suppression.
[0012] As a preferred solution, the direct current bias suppression device can be a resistance type direct current bias suppression device, or a capacitive direct current bias suppression device or other direct current bias suppression device; when it is a resistance type direct current bias suppression device, the resistance can be adjusted. By adjusting the resistance, the direct current bias current on the transformer can be suppressed to ensure that the direct current flowing through the neutral point of the transformer is within the range that the transformer can withstand, thereby ensuring the normal operation of the transformer and the power system.
[0013] Further, the resistance of the resistance type direct current bias suppression device is adjustable in the range of 0-5Ω.
[0014] As a preferred solution, the third disconnector is installed on a device support at a height of not less than 2.5 meters. According to the arrangement requirements of outdoor power distribution devices, the minimum part of the outdoor device arrangement device insulation body should be not less than 2.5m, otherwise a fixed shelter should be set.
[0015] As a preferred solution, the direct current bias suppression device is installed on a device foundation.
[0016] Further, the device foundation is 0.2-0.5 meters high. Considering the installation requirements and maintenance requirements of the direct current bias suppression device foundation height, it is set to be between 0.2-0.5 meters.
[0017] Compared with the prior art, the utility model has the beneficial effects that:
[0018] The disconnector series type direct current bias suppression system provided by the utility model realizes the effect of direct current bias suppression of multiple transformers, reduces the direct current flowing through the neutral point of the transformer to within the range that the transformer can withstand, protects the normal operation of the transformer and the power system, and has the advantages of low cost, flexible arrangement and high adaptability. BRIEF DESCRIPTION OF DRAWINGS
[0019] Figure 1 is a connection diagram of the disconnector series type direct current bias suppression system in the specific embodiment of the utility model;
[0020] Figure 2 is Figure 1 is an installation diagram of the disconnector series type direct current bias suppression system;
[0021] Figure 3 is a connection diagram of another disconnector series type direct current bias suppression system in the specific embodiment of the utility model;
[0022] In the figure: 100, main transformer; 101, first disconnecting switch; 102, air gap; 103, arrester; 104, second disconnecting switch; 105, grounding switch; 106, power cable; 107, DC bias suppression device; 108, current transformer; 109, third disconnecting switch. DETAILED DESCRIPTION
[0023] In order to better explain the utility model, the main content of the utility model is further illustrated below in combination with the drawings and specific embodiments, but the content of the utility model is not limited to the following embodiments only.
[0024] As Figure 1 shown, the utility model discloses a disconnecting switch series type DC bias suppression system, including two main transformers 100, is 1# main transformer and 2# main transformer respectively. The neutral point of two main transformers 100 is connected to each other and is commonly connected to the same DC bias suppression device 107. The neutral point is the neutral point of the high voltage winding of 220kV side of the main transformer 100. The first disconnecting switch 101, the grounding switch 105 and the second disconnecting switch 104 are arranged between the neutral point and the DC bias suppression device 107. The neutral point, the first disconnecting switch 101, the second disconnecting switch 104 and the DC bias suppression device 107 of the main transformer 100 are connected in order. The grounding switch 105 is arranged between the first disconnecting switch 101 and the second disconnecting switch 104. One end of the grounding switch 105 is connected to the second disconnecting switch 104, and the other end is grounded. The second disconnecting switch 104 and the grounding switch 105 constitute a single grounding disconnecting switch, which is the third disconnecting switch 109. The air gap 102, the current transformer 108 and the arrester 103 are arranged between the neutral point of the main transformer 100 and the first disconnecting switch 101. The air gap 102 and the current transformer 108 are connected in series and are commonly connected in parallel with the arrester 103. The first disconnecting switch 101, the second disconnecting switch 104, the grounding switch 105 and the DC bias suppression device 107 are connected and jointly act on the neutral point. The air gap 102 and the arrester 103 are commonly connected to the neutral point, and the arrester 103 and the current transformer 108 are commonly grounded.
[0025] The neutral point of the main transformer 100, the first disconnecting switch 101, the third disconnecting switch 109 and the DC bias suppression device 107 are sequentially connected through the power cable 106.
[0026] The static contact of the second disconnecting switch 104 is arranged at the neutral point side of the main transformer 100, and the moving contact is arranged at the side where the DC bias suppression device 107 is arranged.
[0027] The second disconnecting switch 104 is connected to the high voltage side of the DC bias suppression device 107, and the low voltage side of the DC bias suppression device 107 is grounded.
[0028] The DC bias suppression device 107 is a resistance type DC bias suppression device, and the resistance size is adjustable, and the adjustment range is 0-5Ω.
[0029] As shown in Figure 2 The third disconnector 109 with single grounding is installed on the equipment support, and the installation height is 2.5 meters. The first disconnector 101, the air gap 102, the current transformer 108 and the arrester 103 connected on each main transformer 100 are jointly installed on the same equipment support, and the installation height is 4.15 meters. The equipment support of the third disconnector 109 with single grounding can be flexibly arranged in the range of the field.
[0030] The DC bias suppression device 107 is arranged in a proper open space in the station area; the DC bias suppression device 107 is installed on the equipment foundation, and the equipment foundation height is 0.3 meters.
[0031] The model of the power cable 106 is ZRB-YJV62-26 / 35-1x300.
[0032] The wiring scheme can meet different grounding modes of different main transformer neutral points in the station. Under the operation condition of different grounding requirements of the main transformer neutral point, the opening and closing states of the first disconnector 101, the second disconnector 104 and the grounding switch 105 of different main transformers are shown in Table 1.
[0033] Table 1: Disconnector state under different operation conditions
[0034]
[0035] The DC bias suppression device in Table 1 is the DC bias suppression device 107.
[0036] In another specific embodiment, as shown in Figure 3 The main transformer 100 is provided with three main transformers, which are 1# main transformer, 2# main transformer and 3# main transformer, and the other parts are consistent with the above, and will not be described here.
[0037] The wiring scheme of the disconnector series type DC bias suppression system in the utility model can meet the following requirements: 1) reducing the DC current flowing through the transformer neutral point to the range that can be borne by the transformer, protecting the normal operation of the transformer and the power system; 2) the DC bias suppression of multiple transformers can be realized only by the setting of the cable, the disconnector and the DC bias suppression device, and the treatment cost of the transformer neutral point DC current exceeding the standard is effectively reduced; 3) the connection between the DC bias suppression device, the disconnector and the main transformer adopts power cable wiring, and the arrangement flexibility and adaptability are high, and the DC bias suppression current suppression project of the main transformer with limited arrangement can be applied.
[0038] The above embodiments only express several implementation manners of the present application, which are described in a more specific and detailed manner, but cannot be understood as limiting the scope of the present application. It should be noted that, for those skilled in the art, several modifications and improvements can be made without departing from the concept of the present application, which all belong to the protection scope of the present application.
Claims
1. An isolator series DC bias mitigation system, characterized in that: The application relates to a power supply system for a plurality of main transformers (100), wherein the neutral points of the main transformers (100) are connected to each other and to a same DC bias suppression device (107); the neutral points are neutral points of high-voltage windings or low-voltage windings of the main transformers (100); a first disconnecting switch (101) and a third disconnecting switch (109) are arranged in sequence between the neutral points and the DC bias suppression device (107), and the neutral points, the first disconnecting switch (101), the third disconnecting switch (109) and the DC bias suppression device (107) are connected in series; an air gap (102), a current transformer (108) and a surge arrester (103) are arranged between the first disconnecting switch (101) and the neutral points of the main transformers (100), the air gap (102) and the current transformer (108) are connected in series and are connected in parallel with the surge arrester (103) in common, and the air gap (102) and the surge arrester (103) are connected to the neutral points in common; one side of the third disconnecting switch (109) connected to the first disconnecting switch (101) is grounded.
2. The disconnector series DC bias suppression system according to claim 1, characterized in that: The third disconnecting switch (109) is a single-ground disconnecting switch, comprising a second disconnecting switch (104) and a grounding switch (105); the neutral points, the first disconnecting switch (101) and the second disconnecting switch (104) are connected in series with the DC bias suppression device (107); the grounding switch (105) is arranged on one side of the second disconnecting switch (104) connected to the first disconnecting switch (101); one end of the grounding switch (105) is connected to the second disconnecting switch (104) and the other end is grounded.
3. The disconnector series DC bias suppression system according to claim 2, characterized in that: The first disconnecting switch (101) and the third disconnecting switch (109) and the second disconnecting switch (104) and the DC bias suppression device (107) are connected by power cables (106).
4. The disconnector series DC bias suppression system of claim 2, wherein: The static contact of the second disconnecting switch (104) is arranged on the side of the neutral points of the main transformers (100), and the moving contact is arranged on the side of the DC bias suppression device (107).
5. The disconnector series DC bias suppression system of claim 2, wherein: The second disconnecting switch (104) is connected to the high-voltage side of the DC bias suppression device (107), and the low-voltage side of the DC bias suppression device (107) is grounded.
6. The disconnector series DC bias suppression system of claim 1, wherein: The DC bias suppression device (107) can be a resistance type DC bias suppression device or a capacitive DC bias suppression device; the resistance of the resistance type DC bias suppression device can be adjusted.
7. The disconnector series DC bias suppression system of claim 6, wherein: The resistance of the resistance type DC bias suppression device can be adjusted in a range of 0-5 ohms.
8. The disconnector series DC bias suppression system of claim 1, wherein: The third disconnecting switch (109) is installed on an equipment support, and the installation height is not less than 2.5 meters.
9. The disconnector series DC bias suppression system according to any one of claims 1-8, characterized in that: The DC bias suppression device (107) is installed on an equipment foundation.
10. The disconnector series DC bias suppression system of claim 9, wherein: The equipment foundation has a height of 0.2-0.5 meters.