Oil-immersed reactor and flexible direct-current power transmission system

Abstract

The invention discloses an oil-immersed reactor and a flexible direct-current power transmission system, and relates to the technical field of flexible direct-current power transmission. The oil-immersed reactor comprises six groups of reactance coils; multiple groups of reactance coils corresponding to multiple groups of bridge arms of the flexible direct current power transmission system are integrated, so that two groups of reactance coils corresponding to one group of upper and lower bridge arms form a two-arm two-phase integrated structure, and three groups of reactance coils corresponding to each group of upper bridge arms or each group of lower bridge arms form a single-arm three-phase integrated structure. By means of the two-arm two-phase integrated structure and the single-arm three-phase integrated structure, larger inductance is provided for a single phase, under the condition that the inductance requirement is not changed, the overall size and the occupied area of the reactor are remarkably reduced, and the power density and the space utilization rate of a system are improved.

Description

Technical Field

[0001] This application relates to the field of flexible DC transmission technology, and in particular to an oil-immersed reactor and a flexible DC transmission system. Background Technology

[0002] Reactors are an important component of flexible DC transmission systems. They mainly play a role in suppressing circulating currents between bridge arms and suppressing the bridge arm fault current that rises too quickly during short circuits. In addition, they can control power transmission, filter, and suppress AC side current fluctuations.

[0003] Currently, all flexible DC transmission projects both domestically and internationally adopt dry-type air-core reactor structures. However, dry-type reactors are affected by parameters such as insulation level and current, resulting in a relatively small inductance per unit. Each coil can only be made as a single unit, and the footprint is relatively large when multiple units are connected in series, taking into account the space required for anti-magnetic protection. In addition, the reactor coils are mounted on post insulators, making them relatively sensitive to earthquakes, and placing high requirements on the creepage distance and mechanical strength of the post insulators. Summary of the Invention

[0004] The main objective of this application is to provide an oil-immersed reactor and a flexible DC transmission system, aiming to solve the technical problem of how to reduce the size of the reactor.

[0005] To achieve the above objectives, this application provides an oil-immersed reactor applied to a flexible DC transmission system. The flexible DC transmission system is configured with three upper and lower bridge arms and a three-phase flexible DC transformer. The oil-immersed reactor includes six sets of reactor coils.

[0006] Each reactor coil is connected in series in the electrical circuit of the corresponding upper or lower bridge arm; Between a corresponding set of upper and lower bridge arms, one end of each set of reactor coils is connected to one phase node of a three-phase flexible DC transformer, and the other end of each set of reactor coils is connected to a corresponding rectifier device, forming a two-arm, two-phase integrated structure. Between each upper arm or each lower arm, one end of each of the three sets of reactor coils is connected to a corresponding phase node of the three-phase flexible DC transformer, and the other end of each of the three sets of reactor coils is connected to a corresponding rectifier device, forming a single-arm three-phase integrated structure.

[0007] In one embodiment, the reactance coil is either an air-core coil or an iron-core coil.

[0008] In one embodiment, the body of the two-arm, two-phase integrated structure is a four-column structure with four core columns designed symmetrically, and two sets of reactor coils are respectively arranged on the two middle columns.

[0009] In one embodiment, the single-arm three-phase integrated structure has a five-column structure with five core columns arranged symmetrically and three sets of reactor coils arranged on the three middle columns respectively.

[0010] In one embodiment, the oil-immersed reactor further includes: an auxiliary magnetic shunt; The auxiliary magnetic shunt is located on the outside of the iron yoke of the reactor body to guide and close the loop of the leakage flux generated by the reactance coil.

[0011] In one embodiment, the auxiliary magnetic shunt is a closed frame structure made of silicon steel sheets.

[0012] In one embodiment, the oil-immersed reactor further includes: a plurality of auxiliary magnetic branches, each of which surrounds the main leakage magnetic emission area corresponding to the outer side of the iron yoke of the reactor body.

[0013] In one embodiment, the device body is placed in the oil tank and suspended inside the oil tank.

[0014] In one embodiment, the oil-immersed reactor further includes: a first vibration damping element, a second vibration damping element, and a third vibration damping element; The first damping element is disposed between the reactor coil and its corresponding main magnetic circuit; The second vibration damping element is located between the bottom of the device body and the bottom of the oil tank; The third vibration damping element is located between the side of the vessel body and the side of the oil tank.

[0015] In addition, to achieve the above objectives, this application also proposes a flexible DC transmission system, which includes an oil tank and an oil-immersed reactor as described above.

[0016] This application provides an oil-immersed reactor and a flexible DC transmission system. The oil-immersed reactor includes six sets of reactor coils. By integrating multiple sets of reactor coils corresponding to multiple arms of the flexible DC transmission system, two sets of reactor coils corresponding to one upper or lower arm form a two-arm, two-phase integrated structure, and three sets of reactor coils corresponding to each upper or lower arm form a single-arm, three-phase integrated structure. The two-arm, two-phase integrated structure and the single-arm, three-phase integrated structure provide greater inductance for each phase. While maintaining the same inductance requirement, this significantly reduces the overall size and footprint of the reactor, improving the system's power density and space utilization.

[0017] Furthermore, the oil-immersed reactor proposed in this embodiment has a simple structure, allowing for free selection of the reactor coil to cope with various complex working environments. The reactor body can adopt a four-column / five-column symmetrical design, which can provide a stable and balanced magnetic circuit and strong mechanical support for the integrated coil. While facilitating miniaturization, it can also effectively balance multiphase magnetomotive force, reducing losses and vibrations. The additionally designed auxiliary magnetic shunt can control leakage flux, fundamentally solving the problem of local overheating of structural components such as the oil tank caused by leakage flux, thus improving long-term operational reliability and efficiency. The reactor body is suspended in the oil tank, and with the all-round designed vibration damping material, mechanical vibration and noise are significantly reduced, shock resistance is enhanced, and the service life of the device is extended. Attached Figure Description

[0018] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application.

[0019] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 This is a schematic diagram of the electrical structure of the oil-immersed reactor provided in Embodiment 1 of this application; Figure 2 This is a schematic diagram of the first structure provided for Embodiment 2 of the oil-immersed reactor of this application; Figure 3 This is a second structural schematic diagram of the oil-immersed reactor provided in Embodiment 2 of this application; Figure 4 This is a schematic diagram of a third structure provided in Embodiment 2 of the oil-immersed reactor of this application; Figure 5 This is a schematic diagram of the fourth structure provided in Embodiment 2 of the oil-immersed reactor of this application; Figure 6 A schematic diagram of the structure provided in Embodiment 3 of the oil-immersed reactor of this application; Figure 7 This is another structural schematic diagram of the oil-immersed reactor provided in Embodiment 3 of this application.

[0021] The purpose, features, and advantages of this application will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0022] It should be understood that the specific embodiments described herein are merely illustrative of the technical solutions of this application and are not intended to limit this application.

[0023] To better understand the technical solution of this application, a detailed description will be provided below in conjunction with the accompanying drawings and specific implementation methods.

[0024] This application presents a first embodiment of an oil-immersed reactor, applied to a flexible DC transmission system, such as... Figure 1 As shown, the flexible DC transmission system is equipped with three sets of upper and lower bridge arms and a three-phase flexible DC transformer 100. The oil-immersed reactor includes: six sets of reactor coils 2; Each reactor coil 2 is connected in series in the electrical circuit of the corresponding upper or lower bridge arm; Between a corresponding set of upper and lower bridge arms, one end of the two sets of reactor coils 2 is connected to one phase node of the three-phase flexible DC transformer 100, and the other end of the two sets of reactor coils 2 is connected to a corresponding rectifier device Dx, forming a two-arm two-phase integrated structure 200. Between each upper bridge arm or between each lower bridge arm, one end of each of the three sets of reactor coils 2 is connected to a corresponding phase node of the three-phase flexible DC transformer 100, and the other end of each of the three sets of reactor coils 2 is connected to a corresponding rectifier device Dx, forming a single-arm three-phase integrated structure 300.

[0025] It should be understood that, in this embodiment, Figure 1 The electrical connection diagram of the oil-immersed reactor proposed in this embodiment is shown. The flexible DC transmission system may include a three-phase flexible DC transformer 100, three sets of upper and lower bridge arms, and several rectifier devices Dx, etc. The three-phase interface of the three-phase flexible DC transformer 100 serves as three phase nodes, which are respectively connected to a set of upper and lower bridge arms.

[0026] It should be noted that, as Figure 1 As shown in this embodiment, for any bridge arm (upper bridge arm or lower bridge arm), a reactor coil 2 and a rectifier device Dx are configured. In the electrical circuit corresponding to the upper or lower bridge arm, one end of the reactor coil 2 is connected to one phase node of the three-phase flexible DC transformer 100, and the other end of the reactor coil 2 is connected to a corresponding rectifier device Dx.

[0027] It is easy to understand that in this embodiment, the rectifier device Dx can specifically be a rectifier diode, which is connected to the corresponding reactance coil 2 through its cathode. The anodes of the rectifier diodes configured in each upper bridge arm share a common connection point, and correspondingly, the anodes of the rectifier diodes configured in each lower bridge arm also share a common connection point, so that the current can only flow unidirectionally to the three-phase interface of the three-phase flexible DC transformer 100.

[0028] It should be noted that, in this embodiment, the two-arm two-phase integrated structure 200 refers to an integrated structure formed by integrating two reactor coils 2 of the same set of upper and lower bridge arms. Here, "two phases" does not refer to two phases of the three-phase interface of the three-phase flexible DC transformer 100, but should be understood as two current transmission channels corresponding to a certain phase interface. Therefore, the two-arm two-phase integrated structure 200 proposed in this embodiment should actually be understood as an integrated structure formed by parallel connection of two reactor coils 2 corresponding to the upper and lower bridge arms of the same phase. The single-arm three-phase integrated structure 300 refers to an integrated structure formed by integrating three reactor coils 2 configured in all upper bridge arms or three reactor coils 2 configured in all lower bridge arms. Here, "single arm" does not refer to a single upper bridge arm or a single lower bridge arm, but should be understood as the entirety corresponding to all upper bridge arms or all lower bridge arms. Therefore, the single-arm three-phase integrated structure 300 proposed in this embodiment should actually be understood as an integrated structure formed by parallel connection of three reactor coils 2 corresponding to all upper bridge arms or all lower bridge arms.

[0029] It is easy to understand that, in this embodiment, by setting the electrical connection relationship of the six sets of reactor coils 2 as an integration of the above two structural forms (two-arm two-phase integrated structure 200 and single-arm three-phase integrated structure 300), the physical entity of the reactor, which originally required six installation positions and support structures, is greatly merged, significantly reducing the number of external connection lines and insulation supports. In addition, the above-described two-arm two-phase integrated structure 200 and single-arm three-phase integrated structure 300 can also increase the actual inductance value provided to a single phase of the system. Under the condition that the inductance requirement remains unchanged, the physical volume of a single reactor coil 2 can also be reduced, thereby further reducing the overall volume and footprint of the reactor, making it suitable for space-constrained scenarios such as offshore wind power platforms.

[0030] This application provides an oil-immersed reactor comprising six sets of reactor coils. By integrating multiple sets of reactor coils corresponding to multiple arms of a flexible DC transmission system, two sets of reactor coils corresponding to one upper or lower arm form a two-arm, two-phase integrated structure, and three sets of reactor coils corresponding to each upper or lower arm form a single-arm, three-phase integrated structure. The two-arm, two-phase integrated structure and the single-arm, three-phase integrated structure provide greater inductance for each phase, significantly reducing the overall size and footprint of the reactor while maintaining the same inductance requirement, thereby improving the system's power density and space utilization.

[0031] Based on the first embodiment of the oil-immersed reactor of this application, a second embodiment of the oil-immersed reactor of this application is proposed. In the second embodiment of the oil-immersed reactor of this application, the contents that are the same as or similar to those in the first embodiment described above can be referred to the above description, and will not be repeated hereafter. Based on this, please refer to... Figure 2 , Figure 3 , Figure 4 as well as Figure 5 In this embodiment, the reactor coil 2 is either a hollow coil or an iron-core coil.

[0032] It should be noted that in this embodiment, the hollow coil refers to the reactance coil 2 without an internal ferromagnetic core. Its inductance mainly depends on the geometry and number of turns of the reactance coil 2 itself, exhibiting good linearity and no risk of magnetic saturation. For details, please refer to [reference needed]. Figure 2 and Figure 4 The two physical structures are shown. The iron-core coil refers to a structure where the reactance coil 2 is wound on an iron core column made of stacked silicon steel sheets. Utilizing the high permeability of ferromagnetic materials, a larger inductance can be achieved with a smaller volume and number of turns, which is beneficial for further reducing equipment size. For details, please refer to [reference needed]. Figure 3 and Figure 5 The two solid structures shown are shown.

[0033] Furthermore, in this embodiment, the body of the two-arm two-phase integrated structure 200 is a four-column structure with four core columns designed symmetrically, and two sets of reactor coils 2 are respectively arranged on the two middle columns.

[0034] It should be understood that, in this embodiment, the body refers to the core assembly containing the reactance coil 2 and its directly associated magnetic circuit support structure. For hollow coils, the body mainly includes the reactance coil 2 body and a non-magnetic or low-magnetic structure (which may be referred to as the main magnetic circuit 1) for fixing and guiding magnetic flux. For iron-core coils, the body explicitly includes the iron core 4 (composed of an iron core column and an iron yoke) and the reactance coil 2 body wound on the iron core column.

[0035] It should be noted that, in this embodiment, as Figure 2 and Figure 3 As shown, Figure 2 The diagram shows a two-arm, two-phase integrated structure 200 formed by hollow coil assembly. Figure 3 The diagram shows a schematic of a two-arm, two-phase integrated structure 200 formed by using iron-core coils. In both cases, to accommodate and support the two reactor coils 2 of the two-arm, two-phase integrated structure 200 and optimize the magnetic circuit, the body can adopt a four-column structure, which mainly includes the main magnetic circuit 1, two reactor coils 2, and four core columns. One end of the two reactor coils 2 forms a common node, and the other ends of the two coils are led out separately. The two middle core columns are used to house the two reactor coils 2 (for the iron-core type, these two columns are the iron-core columns), while the side core columns mainly serve as structural supports and constitute part of the magnetic flux loop.

[0036] It is easy to understand that, in this embodiment, the four-column structure provides a stable physical basis and magnetic circuit space for the two-arm two-phase integration, so that the two reactance coils 2 can maintain the necessary electrical isolation and be structurally integrated.

[0037] It is worth noting that in this embodiment, the four core columns are symmetrically and compactly distributed, which is beneficial for magnetic field management.

[0038] Furthermore, in this embodiment, the body of the single-arm three-phase integrated structure 300 is a five-column structure with five core columns arranged symmetrically, and three sets of reactor coils 2 are respectively arranged on the three middle columns.

[0039] It should be noted that, in this embodiment, as Figure 4 and Figure 5 As shown, Figure 4 The diagram shows a single-arm three-phase integrated structure 300 formed by hollow coil assembly. Figure 5 The diagram shows a structural schematic of a single-arm three-phase integrated structure 300 formed by using iron-core coils. In both of the above cases, to integrate three reactor coils 2, the transformer body can adopt a five-column structure, mainly including the main magnetic circuit 1, three reactor coils 2, and five core columns. Both ends of each reactor coil 2 are led out. The three middle core columns are used to house the three reactor coils 2 respectively (for the iron-core type, this means three iron-core columns), and the two outermost side core columns provide structural support and assist in magnetic flux closure.

[0040] It is easy to understand that in this embodiment, the five-column structure matches the symmetry of the three-phase system, which can better balance the three-phase magnetomotive force and reduce the additional losses and vibrations caused by magnetic circuit imbalance.

[0041] Based on the first and / or second embodiments of the oil-immersed reactor of this application, a third embodiment of the oil-immersed reactor of this application is proposed. In the third embodiment of the oil-immersed reactor of this application, the contents that are the same as or similar to those in the first embodiment described above can be referred to the above description and will not be repeated hereafter. Based on this, please refer to... Figure 6 as well as Figure 7 In this embodiment, the oil-immersed reactor further includes: an auxiliary magnetic shunt 5; The auxiliary magnetic shunt 5 is located on the outside of the iron yoke of the reactor body and is used to guide and close the loop to constrain the leakage flux generated by the reactor coil 2.

[0042] It should be understood that in this embodiment, due to the presence of mixed current and fault current in the flexible DC transmission system, both can generate significant leakage flux and electrodynamic force through the two-arm two-phase integrated structure 200 and the single-arm three-phase integrated structure 300 proposed in this embodiment. This can lead to resonance and abnormal temperature rise in other arms and related structures. For example, under the action of AC / DC mixed current, these leakage fluxes may enter the oil tank 3, clamps, and other structural components uncontrollably, resulting in considerable eddy current losses and consequently, local overheating.

[0043] It should be noted that the "body" mentioned in this embodiment can refer to either the body of the aforementioned two-arm, two-phase integrated structure 200 or the body of the aforementioned single-arm, three-phase integrated structure 300. The iron yoke of the body in this embodiment should be understood according to the type of the reactor coil 2. If the reactor coil 2 is an iron-core coil, then the "iron yoke of the body" should be understood as the upper and lower transverse yokes of the iron core 4; if the reactor coil 2 is a hollow coil, then the "iron yoke of the body" should be understood as the structural frame at the top and bottom of the body. In this embodiment, as... Figure 6 As shown, taking a single-arm three-phase hollow structure as an example, in this embodiment, an auxiliary magnetic shunt 5 is installed close to the outside of the iron yoke of the transformer body to provide a low magnetic resistance path for the leakage flux, thereby actively attracting the leakage flux emitted from the end of the reactor coil 2.

[0044] It is easy to understand that in this embodiment, the auxiliary magnetic shunt 5 is made of a highly permeable material, specifically a closed frame structure made of silicon steel sheets stacked or spliced ​​together. This makes the auxiliary magnetic shunt 5 itself a closed magnetic circuit. The attracted leakage magnetic flux forms a closed loop in this magnetic circuit, thus being confined within the shunt and preventing leakage flux from penetrating into external metal parts such as the oil tank 3, fundamentally preventing overheating of the structural components.

[0045] Furthermore, in this embodiment, the oil-immersed reactor also includes: a plurality of auxiliary magnetic branches 5, each of which surrounds the main leakage magnetic emission area corresponding to the outer side of the iron yoke of the reactor body.

[0046] It is easy to understand, please combine Figure 6 In this embodiment, in practice, the number of auxiliary magnetic shunts 5 can be multiple. They can be set above and below the iron yoke of the device body and on both sides (i.e., the main leakage magnetic emission area mentioned above) according to the size of the device body and the leakage magnetic distribution, so as to form a comprehensive shield and ensure that there is no significant leakage magnetic escape area.

[0047] Furthermore, in this embodiment, the device body is placed in the oil tank 3 and suspended inside the oil tank 3.

[0048] It should be understood that, in this embodiment, regardless of whether the reactor coil 2 is a hollow coil or an iron-core coil, its body (reactor coil 2 and its associated magnetic circuit structure) is immersed in the insulating oil of the same oil tank 3. Based on the above oil-immersed design, the reactor as a whole is provided with excellent electrical insulation strength, heat dissipation capacity and environmental protection (moisture-proof, salt spray-proof, dust-proof), fundamentally overcoming the limitations of dry-type reactors in harsh environments.

[0049] It should be noted that in this embodiment, "suspended" does not mean completely non-contact, but rather that the device body is not rigidly fixed inside the oil tank 3. Based on the suspended design, the vibrations generated and transmitted by the device body during operation can be isolated and attenuated, resulting in a very good noise reduction effect.

[0050] Furthermore, in this embodiment, the oil-immersed reactor further includes: a first vibration damping element 8, a second vibration damping element 6, and a third vibration damping element 7; The first vibration damping element 8 is disposed between the reactor coil 2 and its corresponding main magnetic circuit 1; The second vibration damping element 6 is located between the bottom of the device body and the bottom of the oil tank 3; The third vibration damping element 7 is located between the side of the device body and the side of the oil tank 3.

[0051] It should be understood that, in this embodiment, the first damping element 8, the second damping element 6, and the third damping element 7 can all be a viscoelastic material with high internal friction, such as rubber or other composite materials. This material can convert the energy of mechanical vibration into internal energy for dissipation.

[0052] It should be noted that, please refer to... Figure 7 To understand this, in this embodiment, the gap between the reactor coil 2 and the main magnetic circuit 1 (or the core column) is filled with a first vibration damping material 8, which is mainly used to absorb and attenuate the vibration of the reactor coil 2 itself caused by electrodynamic force, and to prevent the vibration from being directly transmitted to the magnetic circuit structure; in this embodiment, the gap between the bottom of the reactor body and the bottom of the oil tank 3 is also filled with a second vibration damping material 6, which is mainly used to bear the weight of the reactor body and isolate the vertical vibration transmission; in this embodiment, the gap between the side of the reactor body and the side wall of the oil tank 3 is also filled with a third vibration damping material 7, which is mainly used to limit the horizontal swing of the reactor body and suppress lateral vibration.

[0053] It is easy to understand that, in this embodiment, based on the damping design in the above three directions, and in conjunction with the insulating oil in the oil tank 3, the reactor body is able to "float" inside the oil tank 3, which further reduces the vibration amplitude, improves the mechanical stability and service life of the reactor product, and at the same time reduces noise pollution to the external environment.

[0054] It is worth noting that, on the one hand, the oil-immersed reactor proposed in this embodiment can be installed on the ground, has a low center of gravity, a sturdy structure, and good vibration resistance; on the other hand, the oil-immersed reactor proposed in this embodiment can be inserted into the valve hall using a dry bushing, eliminating the need for a horizontal through-wall bushing, making assembly and use more convenient.

[0055] Furthermore, this application also provides a flexible DC transmission system, which includes an oil tank and an oil-immersed reactor as described above. Compared with the prior art, the other beneficial effects of the flexible DC transmission system provided in this application are the same as those of the oil-immersed reactor provided in the above embodiments, and the other technical features of the flexible DC transmission system are the same as those disclosed in the embodiments of the oil-immersed reactor, and will not be repeated here.

[0056] The above are merely preferred embodiments of this application and do not limit the patent scope of this application. Any equivalent structural or procedural transformations made using the content of this application's specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the patent scope of this application.

Claims

1. An oil-immersed reactor, characterized in that, This invention is applied to a flexible DC transmission system, which is configured with three upper and lower bridge arms and a three-phase flexible DC transformer. The oil-immersed reactor includes six sets of reactor coils. Each of the aforementioned reactor coils is connected in series in the electrical circuit of the corresponding upper or lower bridge arm; Between a corresponding set of upper and lower bridge arms, one end of each of the two sets of reactor coils is connected to one phase node of the three-phase flexible DC transformer, and the other end of each set of reactor coils is connected to a corresponding rectifier device, forming a two-arm, two-phase integrated structure. Between each of the upper bridge arms or between each of the lower bridge arms, one end of each of the three sets of reactor coils is connected to a corresponding phase node of the three-phase flexible DC transformer, and the other end of each of the three sets of reactor coils is connected to a corresponding rectifier device, forming a single-arm three-phase integrated structure.

2. The oil-immersed reactor as described in claim 1, characterized in that, The reactor coil can be either a hollow coil or an iron-core coil.

3. The oil-immersed reactor as described in claim 1, characterized in that, The body of the two-arm, two-phase integrated structure is a four-column structure with four core columns designed symmetrically. The two sets of reactor coils are respectively arranged on the two middle columns.

4. The oil-immersed reactor as described in claim 1, characterized in that, The single-arm three-phase integrated structure has a five-column structure with five core columns designed symmetrically, and the three sets of reactor coils are respectively arranged on the three middle columns.

5. The oil-immersed reactor as described in any one of claims 3 or 4, characterized in that, The oil-immersed reactor also includes: an auxiliary magnetic shunt; The auxiliary magnetic shunt is located on the outside of the iron yoke of the reactor body and is used to guide and close the loop to constrain the leakage flux generated by the reactance coil.

6. The oil-immersed reactor as described in claim 5, characterized in that, The auxiliary magnetic shunt is a closed frame structure made of silicon steel sheets.

7. The oil-immersed reactor as described in claim 5, characterized in that, The oil-immersed reactor further includes: a plurality of auxiliary magnetic circuits, each of which surrounds the main leakage magnetic emission area corresponding to the outer side of the iron yoke of the reactor body.

8. The oil-immersed reactor as described in any one of claims 3 or 4, characterized in that, The device body is placed in the oil tank and suspended inside the oil tank.

9. The oil-immersed reactor as described in claim 8, characterized in that, The oil-immersed reactor further includes: a first vibration damping element, a second vibration damping element, and a third vibration damping element; The first vibration damping element is disposed between the reactor coil and its corresponding main magnetic circuit; The second vibration damping element is disposed between the bottom of the device body and the bottom of the oil tank; The third vibration damping element is disposed between the side of the vessel body and the side of the oil tank.

10. A flexible DC transmission system, characterized in that, The flexible DC transmission system includes an oil tank and an oil-immersed reactor as described in any one of claims 1-9.

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