10kv hybrid distribution transformer

Abstract

The application discloses a 10kV hybrid distribution transformer and belongs to the technical field of transformers. The 10kV hybrid distribution transformer comprises a three-winding transformer body and a back-to-back converter which are fixedly arranged adjacently. The lateral wall of the box body of the three-winding transformer extends laterally by 10 terminals which are connected with the end of the secondary winding open winding group, the auxiliary winding group, the secondary winding interface and the neutral point respectively. The cabinet body of the back-to-back converter is sequentially provided with a heat dissipation and filtering layer, a power device layer, a strong current connection layer and a weak current control layer along the depth direction, so that the electromagnetic and thermal layered isolation of the high-power element, the strong current loop and the weak current control module is realized. The application eliminates the external long cable through the lateral butt joint of the terminals, reduces the stray inductance and copper loss, and makes the whole machine structure compact through the four-layer layout, so that the industrial application is facilitated.

Description

Technical Field

[0001] This invention belongs to the field of transformer technology, specifically relating to a 10kV hybrid distribution transformer. Background Technology

[0002] Hybrid Distribution Transformer (HDT) is a core device suitable for new distribution networks. Traditional distribution transformers are passive devices with slow response speed and lack of active control capabilities, which cannot meet the active dynamic adjustment requirements of distribution network voltage and power flow after a high proportion of distributed energy is connected. HDT achieves smooth adjustment of grid-side current and load voltage by connecting a power electronic converter to the secondary winding side of the traditional transformer and using control methods such as high-frequency pulse width modulation.

[0003] To meet the high-capacity application requirements of power distribution networks, converters must be equipped with multiple high-power switching devices, filtering components, and energy storage modules. Furthermore, according to traditional design concepts, HDTs typically employ a discrete layout architecture, where the transformer body and the power electronic converter cabinet are two independent equipment entities, electrically connected by external flexible cables. However, in practical industrial applications, this architecture has significant engineering limitations: excessively long external interconnecting cables increase parasitic stray inductance and copper losses in the converter; simultaneously, the discrete layout results in a large cabinet footprint, which is detrimental to the upgrading and renovation of urban power distribution cabinets where space resources are limited.

[0004] Currently, HDTs lack a mature integrated three-dimensional spatial design scheme for transformers and converters, resulting in insufficient compactness of the internal layout and complex spatial assembly. Specifically, within a limited volume, the high-frequency high-voltage main circuit in back-to-back converters generates a large amount of heat and strong electromagnetic fields during operation, directly interfering with the stable operation of the low-voltage control boards, highlighting electro-magnetic-thermal coupling issues. Therefore, to achieve miniaturization and high power density in HDTs, it is urgent to develop an integrated design for transformers and converters to fundamentally improve the overall electro-magnetic-thermal performance of the equipment. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the prior art and provide a 10kV hybrid distribution transformer to solve the problems in the prior art, where the transformer and power electronic converter cabinet are separated and need to be connected by long cables, resulting in large stray inductance, high line copper loss, and the high-frequency high-voltage main circuit in the back-to-back converter generates a lot of heat and strong electromagnetic field during operation, which directly interferes with the stable operation of the weak current control board and the prominent electro-magnetic-thermal coupling problem.

[0006] To achieve the above objectives, the present invention employs the following technical solution: A 10kV hybrid distribution transformer includes a three-winding transformer body and a back-to-back converter that are fixedly arranged adjacently. The three-winding transformer has 10 terminals extending laterally from the side wall of the enclosure. These terminals are the three-phase lead-out terminal of the open winding at the end of the secondary winding, the three-phase interface of the auxiliary winding, the three-phase interface of the secondary winding, and the neutral point interface. The back-to-back converter cabinet contains, sequentially along the direction from the three-winding transformer body to the distance from it, a heat dissipation and filtering layer, a power device layer, a high-voltage connection layer, and a low-voltage control layer. The heat dissipation and filtering layer includes series filter inductors, parallel filter inductors, damping resistors, filter capacitors, and a heat sink. The power device layer includes a series voltage compensation side and a parallel current compensation side, with the power switching elements on the series voltage compensation side and the parallel current compensation side connected via a DC bus capacitor to form a common DC bus. The low-voltage control layer includes a drive circuit module, a detection circuit module, and a control circuit module. The three-phase leads of the open winding at the end of the secondary winding are connected to the AC side of the series voltage compensation power switch element via the series filter inductor; the three-phase interface of the secondary winding is connected to the output side of the series voltage compensation power switch element, and the neutral point interface is connected to the load-side neutral point circuit; the three-phase interface of the auxiliary winding is connected to the AC side of the parallel current compensation power switch element via the parallel filter inductor; the DC sides of the series voltage compensation power switch element and the parallel current compensation power switch element are interconnected through the DC bus capacitor; the damping resistor and the filter capacitor are connected in series to form a filter damping branch, and the filter damping branch is connected in parallel to the output side of the series voltage compensation power switch element and the output side of the parallel current compensation power switch element, respectively; The high-voltage connection layer is provided with a main circuit copper busbar and an insulated cable for realizing the connection. The drive circuit module is connected to the control terminal of the power switch element in the power device layer, the detection circuit module is connected to the current sensor in the high-voltage connection layer, and the control circuit module is signal-connected to the drive circuit module and the detection circuit module.

[0007] A further improvement of the present invention is that: Preferably, the heat dissipation filter layer is further provided with a bottom air intake fan, and the heat sink includes a series voltage compensation side heat sink and a parallel current compensation side heat sink. The series filter inductor, the parallel filter inductor, the damping resistor and the heat sink are all fixed to the heat dissipation filter layer. The bottom air intake fan and the air outlet on the side wall of the cabinet form a forced air cooling channel from bottom to top.

[0008] Preferably, the power device layer is further provided with a soft-start resistor, a soft-start contactor, a bypass contactor, and a thyristor bypass switch; The soft-start resistor and the soft-start contactor are connected in parallel and then in series in the DC bus pre-charge circuit. The bypass contactor is connected in parallel to the AC output terminal of the power switching element on the series voltage compensation side. The thyristor bypass switch is connected in parallel with the bypass contactor.

[0009] Preferably, the high-voltage connection layer is further provided with a circuit breaker and a current sensor; The circuit breaker is connected in series between the three-phase interface of the auxiliary winding and the parallel filter inductor. The current sensor is set on the main current path on the secondary winding side and the output path of the parallel compensation branch to collect the load current and the compensation output current.

[0010] Preferably, the low-voltage control layer is further provided with a switching power supply module, an EMC processing unit, and a series contactor for filter capacitors; The switching power supply module provides isolated auxiliary power to the drive circuit module, detection circuit module and control circuit module. The EMC processing unit is used to suppress electromagnetic interference generated by the operation of power switching elements. The series contactor is used to control the connection and disconnection of the filter damping branch.

[0011] Preferably, the DC bus capacitor has a split capacitor structure, and the series voltage compensation side power switching element and the parallel current compensation side power switching element are both IGBT modules. Their DC sides are connected through the midpoint of the split capacitor to form a common DC bus.

[0012] Preferably, the main circuit copper busbar connects the DC bus capacitor to the power switching elements on the series voltage compensation side and the parallel current compensation side respectively, and the insulated cable completes the switching connection or cross-layer connection.

[0013] Preferably, the driving circuit module includes a series voltage compensation side driving circuit module and a parallel current compensation side driving circuit module, and the detection circuit module includes a series voltage compensation side detection circuit module and a parallel current compensation side detection circuit module. The series voltage compensation side driving circuit module is arranged close to the side of the series voltage compensation side power switching element, and the parallel current compensation side driving circuit module is arranged close to the side of the parallel current compensation side power switching element.

[0014] Preferably, a 10kV high-voltage terminal and a 400V low-voltage terminal are vertically installed on the top of the oil tank of the three-winding transformer body. The 10 horizontally extending terminals are independent of the 10kV high-voltage terminal and the 400V low-voltage terminal and are configured in conjunction with the low-voltage insulating bushing.

[0015] Preferably, the bottom of the three-winding transformer body is provided with a load-bearing base, and the back-to-back converter cabinet is aligned with and locked to the load-bearing base through bottom screw holes; The back-to-back converter cabinet has hanging rings at the four corners of the top, and a louvered air outlet is opened on the upper side wall of the cabinet. A DC terminal is led out from the side wall of the cabinet below the air outlet.

[0016] Compared with the prior art, the present invention has the following beneficial effects: To address the issues of large space occupation and lengthy connecting cables in the discrete design architecture of hybrid distribution transformers (HDTs), this invention discloses a 10kV hybrid distribution transformer, comprising a three-winding transformer body and a back-to-back converter. Multiple terminals extend laterally from the side wall of the three-winding transformer enclosure, passing through docking windows to connect seamlessly with the internal terminals of the converter. The back-to-back converter cabinet has four layers arranged sequentially from the inside out along its depth direction, achieving layered isolation between the heat sink, energy storage capacitor, power switching components, circuit connection copper busbars, and control circuit modules. This solution eliminates long external interconnecting cables through lateral terminal docking, reducing stray inductance and copper losses. Furthermore, the four-layer layout achieves electro-magnetic-thermal isolation between the main high-voltage circuit, the low-voltage control circuit modules, and the heat sink. The overall structure is compact and facilitates industrial application. This invention achieves seamless assembly with the transformer's sidewall-extending terminals and back-to-back converters, shortening the long flexible cable between them and reducing parasitic stray inductance and copper losses. This plug-in integrated design significantly reduces the overall size and footprint, improving compactness and facilitating industrial applications. A four-layer spatial layout is constructed inside the converter cabinet, anchoring heavy magnetic components and heat sinks to the bottom layer; components highly sensitive to electromagnetic interference, such as low-voltage control circuit modules, are parallelly isolated on the outermost layer, and a directional forced-air cooling duct is constructed at the bottom layer. This structure effectively isolates strong magnetic fields from weak electrical signals, offering significant advantages such as compact structure, excellent thermomagnetic isolation, and safe and reliable operation. Attached Figure Description

[0017] Figure 1 Three-view diagram of a 10kV hybrid distribution transformer; Figure 2 The following are plan views of a 10kV hybrid distribution transformer: (a) front view; (b) CAD front view; (c) side view; (d) CAD side view.

[0018] Figure 3 Three-view diagram of a three-winding transformer; (a) is the front view; (b) is the side view; (c) is the top view; Figure 4 Three-view diagrams of the transformer core and coils of the engineering prototype; (a) is the front view; (b) is the side view; (c) is the top view; Figure 5 This is the first layer layout diagram inside the back-to-back converter; Figure 6 This is the second layer layout diagram inside the back-to-back converter; Figure 7 This is a layout diagram of the third layer inside the back-to-back converter. Figure 8 This is a layout diagram of the fourth layer inside the back-to-back converter. Figure 9 This is the main circuit topology diagram of a hybrid distribution transformer; The components include: 1. Three-winding transformer; 2. Back-to-back converter; 3. Hanging ring; 4. Air outlet; 5. DC terminal; 6. Heat sink; 7. 10kV high-voltage terminal; 8. 400V low-voltage terminal; 9. Transformer lateral extension terminal; 10. Main core column; 11. Upper yoke; 12. Lower yoke; 13. Upper clamp; 14. Lower clamp; 15. Winding coil; 16. Three-phase core; 17. Load-bearing base. Detailed Implementation

[0019] The present invention will now be described in further detail with reference to the accompanying drawings: Embodiments of the present invention are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0020] To address the engineering challenges of large space requirements, lengthy connecting cables, and severe electromagnetic interference associated with the discrete design architecture of Hybrid Distribution Transformers (HDTs), this invention proposes a 10kV hybrid distribution transformer for industrial applications. This hybrid distribution transformer includes a three-winding transformer 1 and a back-to-back converter 2. Multiple terminals extend laterally from the side wall of the three-winding transformer 1, passing through docking windows and directly connecting to the internal circuitry of the converter, facilitating electrical signal connection between the transformer and the converter. The back-to-back converter 2 has a four-layer structure arranged sequentially from the inside out along its depth, achieving layered isolation between the heat sink, energy storage capacitor, power switching components, circuit connection copper busbars, and control circuit modules. This design eliminates long external interconnecting cables through lateral terminal docking, reducing stray inductance and copper losses. Furthermore, the four-layer layout achieves electro-magnetic-thermal isolation between the main high-voltage circuit, the low-voltage control circuit modules, and the heat sink. The overall structure is compact and conducive to industrial application.

[0021] like Figure 1As shown, the 10kV hybrid distribution transformer of this invention mainly includes a three-winding transformer 1 and a back-to-back converter 2. The three-winding transformer 1 and the back-to-back converter 2 are not traditionally arranged separately, but rather form a compact integrated distribution transformer structure through a shared load-bearing base, side wall docking windows, and laterally extended dedicated terminals. The cabinet of the back-to-back converter 2 is located on the side of the three-winding transformer 1's enclosure. The inner side wall of the cabinet has docking windows corresponding to the laterally extended terminals of the transformer. Ten laterally extended terminals 9 extend from the side wall of the three-winding transformer 1's enclosure. These ten laterally extended terminals pass through the docking windows into the back-to-back converter 2 and are fixedly connected to the corresponding electrical circuits within the cabinet. Through this connection method, the secondary winding W of the three-winding transformer 1 is connected... 2k Auxiliary winding W 3k CV of back-to-back converter 2 SE Series voltage compensation side and CV SH The parallel voltage compensation side is directly connected, thus avoiding the problem of long-distance external flexible cables being intertwined between the transformer and converter in the traditional discrete scheme.

[0022] The three-winding transformer 1 housing contains a three-phase iron core 16 and winding coils 17, with 10 terminals extending outwards to connect to the back-to-back converter 2. For example... Figure 1 As shown, the transformer enclosure and the back-to-back converter 2 cabinet are seamlessly connected on the side, forming an integrated 10kV-HDT transformer. On the transformer side, the main body uses a high-protection-level corrugated oil tank, with insulating bushings for the 10kV high-voltage and 400V low-voltage terminals vertically installed on the top. The back-to-back converter 2 cabinet is bolted to the side wall of the transformer enclosure. To meet the requirements of hoisting and transportation, high-strength lifting rings 3 are independently installed at each of the four corners of the top of the back-to-back converter 2 cabinet. A matrix of louvered air vents 4 are provided on the upper side wall of the converter cabinet. These vents 4 correspond to the ends of the internal heat sink and forced air cooling channels, facilitating the removal of heat carried away by the internal forced air cooling. Below the air vents 4, on the side wall of the cabinet, DC terminals 5 with positive and negative polarity are led out, providing a standardized physical interface for the subsequent AC / DC hybrid distribution network and distributed DC power supply access.

[0023] See Figure 2The top of the oil tank of the three-winding transformer 1 is vertically equipped with a 10kV high-voltage terminal 7 and a 400V low-voltage terminal 8; the 10 transversely extending transformer terminals 9 are independent of the 10kV high-voltage terminal 7 and the 400V low-voltage terminal 8, and the 10 transversely extending transformer terminals 9 are configured with low-voltage insulating bushings. The 10kV high-voltage terminal 7 and the 400V low-voltage terminal 8 are dedicated to the connection of conventional power frequency grid lines, and the 10 transversely extending transformer terminals 9 are dedicated to the connection with the back-to-back converter 2. Therefore, the transversely extending terminals and the top bushing terminals are independent of each other in terms of purpose, location and service object.

[0024] like Figure 3 As shown, the 10 terminals extend laterally from the side wall of the tank of the three-winding transformer 1, thus enabling connection to the back-to-back converter 2. Specifically, the terminals are c... 2f b 2f a 2f n 2f z 2w y 2w x 2w c 3w b 3w a 3w For ease of description, the terminal markings in this embodiment follow the following naming rules: letters a, b, and c correspond to phases A, B, and C; letters x, y, and z correspond to the three-phase output terminals on the other side of the corresponding winding; the number 2 indicates the connection to the secondary winding W. 2k The relevant circuit, the number 3 indicates the connection with the auxiliary winding W. 3k The relevant circuits; the letter 'w' indicates the winding-side terminal directly led out from the transformer winding body, the letter 'f' indicates the interface terminal facing the converter's filter / compensation branch, and the letter 'n' indicates the neutral point interface terminal. Where, x 2w y 2w z 2w For secondary winding W 2k The three-phase leads of the end open winding, a 3w b 3w c 3w For auxiliary winding W 3k With parallel voltage compensation side CV SH The corresponding three-phase interface, a 2f b 2f c 2f and n 2f Together they form the secondary winding W 2k With series voltage compensation side CV SE The corresponding three-phase / neutral point interface, where a 2f b 2f c 2f For the three-phase interface of the secondary winding, n 2fFor neutral point interfaces; specifically, x 2w y 2w z 2w After entering the converter cabinet, connect to the CV. SE Side filter inductor L SE At the input terminal, the secondary winding is connected in series with the voltage compensation circuit; a 3w b 3w c 3w via circuit breaker S x and filter inductor L SH Access CV SH Parallel compensation main circuit; a 2f b 2f c 2f With CV SE The three-phase compensation voltage injection path on the output side is connected accordingly, n 2f Then with C 2f R 2f The corresponding branch and the neutral point circuit on the load side are connected.

[0025] The 10 laterally extending terminals are located above the side wall of the transformer tank. A sealing assembly prevents potential leakage of insulating oil through this transverse through-structure, and strict electrical safety creepage distances are maintained between the terminals. The 10kV and 400V winding leads inside the transformer are still led out through the top insulator bushing. The bottom of the three-winding transformer 1 is equipped with a load-bearing base. The back-to-back converter 2 cabinet is aligned and locked to the load-bearing base via bottom screw holes. Furthermore, a load-bearing base channel steel is welded to the bottom of the transformer tank. This base supports the weight of the transformer body and serves as a fixing reference for the back-to-back converter 2.

[0026] The electromagnetic body of the three-winding transformer 1 includes a three-phase iron core 16 and winding coils 17. The three-phase iron core 16 consists of a three-phase main iron core column 10, an upper yoke 11, and a lower yoke 12 forming a closed three-phase magnetic circuit. The upper and lower ends are respectively fastened by an upper clamp 13 and a lower clamp 14. Each phase main iron core column 10 has a primary winding, a secondary winding, and an auxiliary winding concentrically wound on it. Figure 4 As shown, the three-winding transformer 1 has a three-phase structure. Its three-phase core mainly consists of three-phase main core columns 10, upper yoke 11, and lower yoke 12, forming a closed three-phase magnetic circuit. The upper and lower ends of the core are secured by upper clamp 13 and lower clamp 14, respectively. Figure 4 (c) It can be seen that the three windings of each phase are concentrically layered around the main iron core column 10; specifically, the primary winding W 1a W 1b W 1c Secondary winding W 2a W 2b W 2cAuxiliary winding W 3a W 3b W 3c The windings are concentrically wound on the main iron core columns 10 of phases A, B, and C. To accelerate the circulation of the cooling oil, each winding consists of two layers with an oil channel in between.

[0027] The internal space of the back-to-back converter 2 includes four modules, with the four layers arranged sequentially from the inside to the outside along the depth direction. These four layers, from the inside out, are the first, second, third, and fourth layers, respectively providing electro-magnetic-thermal isolation for the heat sink, power components, connecting copper busbars, and control circuit modules. In this invention, the inner side is the side of the back-to-back converter 2 cabinet facing the three-winding transformer 1 enclosure and close to the cabinet back panel, while the outer side is the side away from the three-winding transformer 1 enclosure and facing the cabinet door.

[0028] like Figure 5 As shown, the first layer of the back-to-back converter 2 is arranged close to the back panel of the cabinet, located on the side of the cabinet closest to the three-winding transformer 1, and belongs to the heat dissipation and filtering layer; it contains a filter inductor, damping resistor, aluminum heat sink, bottom intake fan, and terminal area, wherein the filter inductor includes CV SE Series filter inductor L SE CV SH Parallel filter inductor L SH Damping resistors include the load-side damping resistor R. 2f Grid-side damping resistor R SHf Load-side filter capacitor C 2f And the grid-side filter capacitor C SHf The heat sink includes thyristors TH. SE Heat sink and CV SE The heatsink, and the CV SH The heat sink, in which the thyristor TH SE and CV SE The heatsink area is larger than CV SH The heat sink area. It should be noted that the specific locations of the various components in this layer can be arranged in functional groups. For example, two damping resistors are jointly positioned next to the side wall of the back-to-back converter 2, and two filter inductors are positioned opposite each other on both sides of the cabinet's side wall. The terminal area is located inside the two damping resistors, and the two heat sinks are surrounded by one side wall of the cabinet, the two types of filter inductors, and the terminal area. From this structure, it can be seen that arranging the transversely extending terminals 9 of the transformer in a row facilitates a compact internal structure for the entire converter.

[0029] The 10 transformer horizontally extending terminals 9 are inserted into the pre-reserved access holes on the back panel of the cabinet according to... Figure 1After completing the electrical connections, the filter inductor, damping resistor, and heat sink, as heavy and high-heat-generating components within the system, are centrally anchored in the first layer. This spatial layout relies on the back panel and base of the back-to-back converter 2 cabinet to construct a high-strength, rigid load-bearing foundation. Simultaneously, in conjunction with the bottom intake fan, a vertical forced air cooling channel is formed from bottom to top, guiding the cooling airflow preferentially through the heat sink and high-heat-density areas, thereby quickly extracting heat out of the cabinet. This structural arrangement places the heat sink, used for heat dissipation, in a relatively central position within the entire cabinet. On one hand, the heat sink is in contact with the intake fan area; on the other hand, it is positioned between the filter inductor and resistor, effectively reducing the impact of localized temperature rise on surrounding components. Furthermore, a second layer can be installed on top of it to cool the power devices on the second layer.

[0030] like Figure 6 As shown, the second layer is located outside the first layer and belongs to the power device layer. Specifically, it is set outside the two heat sinks. This layer is still surrounded by the side wall of the cabinet, two types of filter inductors, and damping resistors. All power devices in this layer are fixedly connected to the corresponding heat sinks through device circuit boards and insulating thermal interfaces. The power devices include soft-start resistors R. D DC bus capacitor C D Soft starter contactor S D Bypass contactor S SE Power switching module (IGBT), thyristor bypass switch T HSE The connection hole area is identical to the first layer's connection hole area, ensuring the insertion length of the terminals. This connection hole area corresponds to the wiring terminals of the previous layer and to the copper busbars, cables, or wiring terminals of the subsequent layer. The power switch module includes a CV... SE Side IGBT and CV SH Side-mounted IGBTs. The semiconductor power devices of the second layer are arranged in close proximity to the aluminum heat sink of the first layer, forming an extremely short heat conduction path; simultaneously, CV SE Side and CV SH The side components are arranged as relatively independent power units along the depth of the cabinet. Specifically, CV SE Side IGBT module and T HSE S SE Together they form a series voltage compensation and bypass unit, CV SH The side IGBT modules form a parallel current compensation unit, and the DC bus capacitor C D It is placed between the two types of power units to form a shared DC energy storage hub, and a soft-start resistor R is configured on the side. D With soft start contactor S D These two components constitute a current-limiting pre-charge circuit for the DC bus. This is to achieve CV... SEThe connection and disconnection of the series compensation branch and the load-side circuit, in a 2f b 2f c 2f The corresponding injection-side interface and L SE C 2f / R 2f A front-end switch S is installed between the common nodes of the branch roads. F CV SH Side by C SHf and R SHf The filter damping branch is connected in series with a contactor S at its front end. SH The contactor S SH It should be noted that the specific locations of the various devices in this layer can be arranged in functional groups to control the connection and disconnection of the filter damping branch.

[0031] In this layer, power semiconductor devices and their corresponding heat sinks should be arranged vertically to shorten the heat conduction path; DC bus capacitor C D Arranged in CV SE Side and CV SH Between the side power units, to shorten the DC bus loop; soft-start resistor R D With soft start contactor S D They should be arranged close together to form a complete pre-charge branch. If extending further to the third and fourth layers, the current sensor should be placed close to the main branch being measured, and the drive module should be placed close to the side of its corresponding power device.

[0032] like Figure 7 As shown, the third layer is located outside the second layer and is a high-voltage connection layer. It contains the main circuit copper busbar, insulated cables, and circuit breaker S. x A current sensor is used to connect the electrical components in the first and second layers. The main circuit copper busbar extends each phase compensation circuit to the corresponding filter inductor and transformer lateral extension terminals 9 groups in the first layer; insulated cables are used to complete cross-layer connections, turning connections, or flexible lead-out connections where direct arrangement of rigid copper busbars is not suitable. Specifically, the upper part of the third layer has access terminals corresponding one-to-one with the transformer lateral extension terminals 9. After entering the cabinet, the 10 lateral extension terminals are first connected to these access terminals and then connected to the lower circuit via the main circuit copper busbar or insulated cables, and to the auxiliary winding W. 3k Related to a 3w b 3w c 3w The terminals are led out through the third layer of copper busbar and connected in series with the circuit breaker S. x Circuit breaker S x Circuit breaker S is located above the DC bus capacitor CD side. x With CV SH Branch and i 3kThe circuit where the current sensor is located is connected to enable the connection, disconnection, and fault isolation of the parallel compensation branch; and is connected to the secondary winding W. 2k The main current path related to the load side passes through the third layer i 2k After the current sensor, then with CV SE The relevant copper busbars on the side and the first layer of filter branches are connected; at the same time, the main circuit copper busbars of the third layer will also connect the DC bus capacitor C of the second layer. D respectively with CV SE Side IGBT module, CV SH Side IGBT module connection, and through insulated cables to complete the switching connection or cross-layer connection; the i 2k i 3k The sampling signal from the current sensor is sent to the fourth-layer detection circuit module via a dedicated sampling signal harness. The load current sensor is located at W... 2k On the main current path related to the load side, CV SH The output current sensor is installed on the output path of the parallel compensation branch, and the sampling signals of both are sent to the detection and control unit on the fourth layer through the sampling signal harness. In this layer, the copper busbars, cables, protection and measuring devices of the high current loop are centrally arranged on the third layer, realizing the independent layering of high-voltage wiring, forming a physical isolation distance with the low-voltage module on the fourth layer, and meeting the electrical clearance and safety specifications for door opening and maintenance.

[0033] like Figure 8 As shown, the fourth layer is located on the outermost side and belongs to the low-voltage control layer. This layer completely covers the aforementioned filter inductor and the entire third layer, and it houses a drive circuit module, a detection circuit module, a control circuit module, a switching power supply module, an EMC processing unit, filter capacitors, and their series contactors. Preferably, it is located near the CV. SE CV arranged on one side of the power unit SE Side drive circuit module and CV SE Side detection circuit module, close to CV SH CV arranged on one side of the power unit SH Side drive circuit module and CV SH Side detection circuit module, the thyristor T HSE Trigger control is achieved by a dedicated circuit module; the switching power supply module provides isolated auxiliary power to the various drive, detection, and control circuits within the device; and the EMC processing unit suppresses electromagnetic interference generated by the operation of the main power switching devices in the second layer. 2f With C SHf respectively with L SE L SH and the corresponding damping resistor R 2f R SHf Together they constitute CV SE Side CV SHThe filter / damping branch on the side is used to suppress high-frequency harmonics generated during the converter switching process, mitigate voltage and current spikes, reduce resonance risk, and improve the quality of the compensation waveform; and with C 2f With C SHf The corresponding series contactor S SE S SH This is used to control the connection and disconnection of corresponding filter branches, so as to avoid the capacitor being hard-connected to the main circuit for a long time during start-up, shutdown, fault isolation, or maintenance, and to reduce switching impact. Since the fourth layer is closest to the cabinet door, it facilitates the centralized arrangement of the contactor execution circuit and status detection circuit with the fourth-layer drive / detection / control module, which is also beneficial for later debugging, maintenance, and replacement. At the same time, this layer is far from the high heat source areas of the first and second layers, which is more conducive to ensuring the operational stability of these devices. In this layer, the current sensor of the third layer feeds back the collected branch current to the fourth-layer detection circuit module. The detection circuit module isolates, conditions, or converts the sampled signal before sending it to the control function unit; the control circuit module sends the signal to the CV according to the detection result. SE Side drive function unit, CV SH Side drive functional unit and thyristor T HSE The dedicated drive unit outputs control commands and sends them to contactor S. SE Contactor S SH and soft start contactor S D The execution circuit outputs switching signals. The fourth layer is the layer closest to the cabinet door and has the largest distance from the high magnetic field and high heat source areas of the first and second layers. This layout structure can ensure the operational stability of the weak current PCB modules in the layer, and at the same time facilitate the debugging, wiring inspection and maintenance of the device.

[0034] like Figure 9 As shown, the HDT of the present invention includes a three-winding transformer 1 and a back-to-back converter 2; specifically, the main transformer includes a primary winding W connected to the 10kV grid side. 1k Secondary winding W 2k Auxiliary winding W 3k Among them, the primary winding W 1k Connected to the 10kV grid side, secondary winding W 2k Set with CV SE The relevant series compensation circuit winding, auxiliary winding W 3k Parallel connection with CV SH The relevant parallel compensation circuit windings. Secondary winding W 2k One side is a 2f b 2f c 2f and n 2f Interface, as a CV SE Injection-side interface of series compensation branch; secondary winding W 2k The other side is x2w y 2w z 2w The interface serves as the open-winding output side interface and is connected via a series filter inductor. L SE With CV SE Connection. Auxiliary winding W 3k Forming a 3w b 3w c 3w Interface, and via circuit breaker S x and parallel filter inductor L SH Access CV SH The back-to-back converter 2 includes a voltage compensation converter CV connected in series with the load circuit. SE and the auxiliary winding W 3k Parallel-side current-compensated converter CV SH Both share a DC bus split capacitor. C D This forms a back-to-back converter structure with a common DC bus. Secondary winding W 2k The end adopts an open winding structure and is filtered by an inductor. L SE With CV SE Serial, CV SE A thyristor T is connected in parallel on the side. HSE With contactor S SE Constructing a bypass switching unit, CV SE A filter capacitor is also installed on the side. C 2f With damping resistor R 2f The filter damping branch is formed. Two soft-start resistors are connected in series on the DC bus. R D Each soft-start resistor R D A soft-start contactor is connected in parallel. S D This forms the pre-charging branch; CV SH A filter capacitor is connected in parallel on the side. C SHf With damping resistor R SHf The filter damping branch formed by this.

[0035] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential," etc., indicating orientation or positional relationships, are based on the orientation or positional relationships shown in the accompanying drawings and are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. Furthermore, features defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, unless otherwise stated, "a plurality of" means two or more. In the description of this invention, "above" or "below" a second feature may include direct contact between the first and second features, or it may include contact between the first and second features not being in direct contact but through another feature between them.

[0036] In the description of this invention, the terms "above," "over," and "on top" for the first feature and the second feature include the first feature being directly above or diagonally above the second feature, or simply indicating that the first feature is at a higher horizontal level than the second feature.

[0037] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0038] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0039] Although embodiments of the invention have been shown and described, those skilled in the art will understand that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the claims and their equivalents.

[0040] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A 10kV hybrid distribution transformer, characterized in that, This includes adjacent, fixedly arranged three-winding transformer bodies and back-to-back converters; The three-winding transformer has 10 terminals extending laterally from the side wall of the enclosure. These terminals are the three-phase lead-out terminal of the open winding at the end of the secondary winding, the three-phase interface of the auxiliary winding, the three-phase interface of the secondary winding, and the neutral point interface. The back-to-back converter cabinet contains, sequentially along the direction from the three-winding transformer body to the distance from it, a heat dissipation and filtering layer, a power device layer, a high-voltage connection layer, and a low-voltage control layer. The heat dissipation and filtering layer includes series filter inductors, parallel filter inductors, damping resistors, filter capacitors, and a heat sink. The power device layer includes a series voltage compensation side and a parallel current compensation side, with the power switching elements on the series voltage compensation side and the parallel current compensation side connected via a DC bus capacitor to form a common DC bus. The low-voltage control layer includes a drive circuit module, a detection circuit module, and a control circuit module. The three-phase leads of the open winding at the end of the secondary winding are connected to the AC side of the series voltage compensation power switch element via the series filter inductor; the three-phase interface of the secondary winding is connected to the output side of the series voltage compensation power switch element, and the neutral point interface is connected to the load-side neutral point circuit; the three-phase interface of the auxiliary winding is connected to the AC side of the parallel current compensation power switch element via the parallel filter inductor; the DC sides of the series voltage compensation power switch element and the parallel current compensation power switch element are interconnected through the DC bus capacitor; the damping resistor and the filter capacitor are connected in series to form a filter damping branch, and the filter damping branch is connected in parallel to the output side of the series voltage compensation power switch element and the output side of the parallel current compensation power switch element, respectively; The high-voltage connection layer is provided with a main circuit copper busbar and an insulated cable for realizing the connection. The drive circuit module is connected to the control terminal of the power switch element in the power device layer, the detection circuit module is connected to the current sensor in the high-voltage connection layer, and the control circuit module is signal-connected to the drive circuit module and the detection circuit module.

2. The 10kV hybrid distribution transformer according to claim 1, characterized in that, The heat dissipation filter layer is also provided with a bottom air intake fan. The heat sink includes a series voltage compensation side heat sink and a parallel current compensation side heat sink. The series filter inductor, parallel filter inductor, damping resistor and heat sink are all fixed to the heat dissipation filter layer. The bottom air intake fan and the air outlet on the side wall of the cabinet form a forced air cooling channel from bottom to top.

3. The 10kV hybrid distribution transformer according to claim 1, characterized in that, The power device layer is also provided with a soft-start resistor, a soft-start contactor, a bypass contactor, and a thyristor bypass switch. The soft-start resistor and the soft-start contactor are connected in parallel and then in series in the DC bus pre-charge circuit. The bypass contactor is connected in parallel to the AC output terminal of the power switching element on the series voltage compensation side. The thyristor bypass switch is connected in parallel with the bypass contactor.

4. The 10kV hybrid distribution transformer according to claim 1, characterized in that, The high-voltage connection layer is also equipped with a circuit breaker and a current sensor; The circuit breaker is connected in series between the three-phase interface of the auxiliary winding and the parallel filter inductor. The current sensor is set on the main current path on the secondary winding side and the output path of the parallel compensation branch to collect the load current and the compensation output current.

5. The 10kV hybrid distribution transformer according to claim 1, characterized in that, The low-voltage control layer is also equipped with a switching power supply module, an EMC processing unit, and a series contactor for filter capacitors. The switching power supply module provides isolated auxiliary power to the drive circuit module, detection circuit module and control circuit module. The EMC processing unit is used to suppress electromagnetic interference generated by the operation of power switching elements. The series contactor is used to control the connection and disconnection of the filter damping branch.

6. The 10kV hybrid distribution transformer according to claim 1, characterized in that, The DC bus capacitor has a split capacitor structure. The series voltage compensation side power switching element and the parallel current compensation side power switching element are both IGBT modules. Their DC sides are connected through the midpoint of the split capacitor to form a common DC bus.

7. The 10kV hybrid distribution transformer according to claim 1, characterized in that, The main circuit copper busbar connects the DC bus capacitor to the power switching elements on the series voltage compensation side and the parallel current compensation side, respectively, and the insulated cable completes the turning connection or cross-layer connection.

8. The 10kV hybrid distribution transformer according to claim 1, characterized in that, The drive circuit module includes a series voltage compensation side drive circuit module and a parallel current compensation side drive circuit module. The detection circuit module includes a series voltage compensation side detection circuit module and a parallel current compensation side detection circuit module. The series voltage compensation side drive circuit module is arranged close to the power switching element on the series voltage compensation side, and the parallel current compensation side drive circuit module is arranged close to the power switching element on the parallel current compensation side.

9. The 10kV hybrid distribution transformer according to claim 1, characterized in that, The top of the oil tank of the three-winding transformer body is vertically equipped with 10kV high-voltage terminals and 400V low-voltage terminals. The 10 horizontally extending terminals are independent of the 10kV high-voltage terminals and 400V low-voltage terminals and are configured in conjunction with the low-voltage insulating bushing.

10. The 10kV hybrid distribution transformer according to claim 1, characterized in that, The bottom of the three-winding transformer body is provided with a load-bearing base, and the back-to-back converter cabinet is aligned with and locked to the load-bearing base through the bottom screw holes. The back-to-back converter cabinet has hanging rings at the four corners of the top, and a louvered air outlet is opened on the upper side wall of the cabinet. A DC terminal is led out from the side wall of the cabinet below the air outlet.

Images