Hybrid transformer and method for regulating the output voltage thereof

Abstract

The application discloses a hybrid transformer and an output voltage regulating method thereof. The hybrid transformer comprises an electromagnetic power frequency transformer and a power electronic converter module. The electromagnetic power frequency transformer is provided with at least one secondary winding. The power electronic converter module is electrically connected with the secondary winding. The power electronic converter module is configured with a filter circuit. The filter circuit comprises a filter capacitor and a converter-side filter inductor. The secondary winding is connected to the filter circuit. An equivalent inductance of the secondary winding and the filter capacitor and the converter-side filter inductor form a filter loop. An inductance value of the equivalent inductance is matched with an inductance value required for grid-side filtering. The secondary winding is connected to the filter circuit. The equivalent inductance of the secondary winding and the filter capacitor and the converter-side filter inductor form the filter loop. The inductance value of the equivalent inductance is matched with the inductance value required for the grid-side filtering. Therefore, the grid-side filter inductor is not required to be independently arranged. The integration of the hybrid transformer is improved.

Description

Technical Field

[0001] This application relates to the field of power distribution equipment technology, and in particular to a hybrid transformer and its output voltage regulation method. Background Technology

[0002] With the large-scale integration of new energy sources into the power distribution network, power distribution equipment is gradually evolving from simple voltage transformation to functions such as voltage regulation, reactive power compensation, and three-phase imbalance control. As a result, hybrid transformers have become important equipment for achieving power quality regulation in the power distribution network.

[0003] Existing hybrid transformers combine power frequency transformers with power electronic converters. The transformer undertakes voltage transformation and power transmission, while the converter uses independent filter inductors and filter capacitors to form a filter circuit, thereby filtering out high-frequency switching harmonics.

[0004] In the existing structure, the transformer winding and the converter filter inductor are set separately, and the system needs to be configured with an additional independent filter inductor, which limits the further improvement of the integration of the hybrid transformer. Summary of the Invention

[0005] In view of the shortcomings of the prior art, this application provides a hybrid transformer and its output voltage regulation method to solve the problem that the existing hybrid transformers require independent setting of filter inductors, which leads to limited system integration.

[0006] To achieve the above objectives, this application provides the following technical solution:

[0007] The first aspect of this application provides a hybrid transformer, which includes an electromagnetic power frequency transformer and a power electronic converter module;

[0008] The electromagnetic power frequency transformer is provided with at least one secondary winding, and the power electronic converter module is electrically connected to the secondary winding.

[0009] The power electronic converter module is equipped with a filter circuit, which includes a filter capacitor and a converter-side filter inductor.

[0010] The secondary winding is connected to the filter circuit. The equivalent inductance of the secondary winding, together with the filter capacitor and the converter-side filter inductance, forms a filter loop. The inductance value of the equivalent inductance matches the inductance value required for the grid-side filtering of the filter circuit.

[0011] Optionally, in the above-mentioned hybrid transformer, the secondary winding includes a first secondary winding and a second secondary winding, and the filter circuit includes a first filter circuit and a second filter circuit.

[0012] The first secondary winding is electrically connected to the first filter circuit, and the second secondary winding is electrically connected to the second filter circuit;

[0013] The first equivalent inductance of the first secondary winding, together with the first filter capacitor and the first converter-side filter inductance in the first filter circuit, constitutes the first filter circuit.

[0014] The second equivalent inductance of the second secondary winding, together with the second filter capacitor and the second converter-side filter inductance in the second filter circuit, constitute the second filter loop.

[0015] Optionally, in the above-described hybrid transformer, the first secondary winding is electrically connected to the load output terminal of the hybrid transformer;

[0016] The second secondary winding is electrically connected to the power supply terminal of the power electronic converter module.

[0017] Optionally, in the above-mentioned hybrid transformer, the first secondary winding and the second secondary winding are respectively provided with an inter-turn insulation structure, an inter-layer insulation structure and a winding-to-ground insulation structure, wherein the inter-turn insulation structure, the inter-layer insulation structure and the winding-to-ground insulation structure are formed of insulating material.

[0018] Optionally, in the above-mentioned hybrid transformer, the electromagnetic power frequency transformer includes a high-voltage winding, a low-voltage winding, and winding cooling oil channels.

[0019] The winding cooling oil channel is located between the high-voltage winding and the low-voltage winding.

[0020] Optionally, in the hybrid transformer described above, the power electronic converter module includes power devices that are electrically connected to the filter circuit.

[0021] Optionally, in the above-mentioned hybrid transformer, the power electronic converter module is disposed outside the electromagnetic power frequency transformer and is fixedly connected to the electromagnetic power frequency transformer.

[0022] Optionally, in the above-mentioned hybrid transformer, the electromagnetic power frequency transformer is provided with reinforcing ribs on its outer side;

[0023] The power electronic converter module is fixedly connected to the reinforcing rib by bolts;

[0024] The AC output terminal of the power electronic converter module is electrically connected to the lead-out terminal of the secondary winding via a copper busbar.

[0025] Optionally, in the above-described hybrid transformer, the hybrid transformer includes a voltage detection module and a controller;

[0026] The voltage detection module is connected to the output voltage port of the hybrid transformer, and the output terminal of the voltage detection module is connected to the controller;

[0027] The controller is connected to the power electronic converter module.

[0028] A second aspect of this application provides an output voltage regulation method for a hybrid transformer, applied to a hybrid transformer provided in the first aspect of this application. The output voltage regulation method includes:

[0029] Obtain the electrical parameters of the output terminal of the hybrid transformer, and determine the power quality control requirements based on the electrical parameters;

[0030] Based on the power quality control requirements, a control signal for the power electronic converter module is generated, and the power electronic converter module is controlled to perform power conversion based on the control signal to adjust the output voltage of the hybrid transformer;

[0031] During the voltage regulation process of the power electronic converter module, the high-frequency harmonics generated by the power electronic converter module are filtered out through a filter circuit;

[0032] After filtering is completed, the output voltage of the adjusted hybrid transformer output terminal is obtained;

[0033] The power electronic converter module is further controlled based on the output voltage to maintain the output voltage of the hybrid transformer at a preset output voltage.

[0034] This application provides a hybrid transformer comprising an electromagnetic power frequency transformer and a power electronic converter module. The electromagnetic power frequency transformer has at least one secondary winding. The power electronic converter module is electrically connected to the secondary winding and is equipped with a filter circuit. The filter circuit includes a filter capacitor and a converter-side filter inductor. The secondary winding is connected to the filter circuit, and the equivalent inductance of the secondary winding, the filter capacitor, and the converter-side filter inductor form a filter loop. The inductance value of the equivalent inductance matches the inductance value required for grid-side filtering in the filter circuit. Therefore, by connecting the secondary winding to the filter circuit, the equivalent inductance of the secondary winding, the filter capacitor, and the converter-side filter inductor form a filter loop, and the inductance value of the equivalent inductance matches the inductance value required for grid-side filtering, thus eliminating the need for a separate grid-side filter inductor and improving the integration of the hybrid transformer. Attached Figure Description

[0035] 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, the drawings described below are only embodiments of this application. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0036] Figure 1 This is a first structural schematic diagram of a hybrid transformer provided in an embodiment of this application;

[0037] Figure 2 This is a schematic diagram of a second structure of a hybrid transformer provided in an embodiment of this application;

[0038] Figure 3 This is a schematic diagram of a reinforced insulation design provided in an embodiment of this application;

[0039] Figure 4 This is a schematic diagram of an integrated structure of a hybrid transformer provided in an embodiment of this application;

[0040] Figure 5 This is a flowchart illustrating a method for regulating the output voltage of a hybrid transformer, as provided in an embodiment of this application. Detailed Implementation

[0041] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0042] In this application, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0043] As the background technology shows, existing hybrid transformers typically separate the power frequency transformer and the power electronic converter, with an additional independent grid-side filter inductor configured in the filter circuit of the power electronic converter module. While this structure can achieve high-frequency harmonic filtering, it does not fully utilize the equivalent inductance of the secondary winding itself, resulting in a large number of filtering components and a large device size, thus limiting further improvements in the integration of hybrid transformers. Therefore, how to ensure that the equivalent inductance of the secondary winding simultaneously meets the impedance design requirements of the electromagnetic power frequency transformer and the grid-side filtering needs of the filter circuit, and on this basis achieve stable power quality regulation, is a technical problem that urgently needs to be solved in this field.

[0044] Therefore, the hybrid transformer provided in this application embodiment is described below. Figure 1 The hybrid transformer includes an electromagnetic power frequency transformer 1 and a power electronic converter module 2.

[0045] The electromagnetic power frequency transformer 1 is equipped with at least one secondary winding W, and the power electronic converter module 2 is electrically connected to the secondary winding W.

[0046] The power electronic converter module 2 is equipped with a filter circuit, which includes a filter capacitor C and a converter-side filter inductor L.

[0047] The secondary winding W is connected to the filter circuit. The equivalent inductance of the secondary winding W, together with the filter capacitor C and the converter-side filter inductance L, forms a filter loop. The inductance value of the equivalent inductance matches the inductance value required for the grid-side filtering of the filter circuit.

[0048] It is understandable that the equivalent inductance of the secondary winding W refers to the inductance characteristics exhibited by the secondary winding under the operating conditions of a hybrid transformer. To enable this equivalent inductance to perform grid-side filtering, when designing the electromagnetic power frequency transformer 1, the inductance value required for grid-side filtering of the filter circuit can be used as a target constraint condition for the secondary winding structure design. By adjusting at least one of the following: the number of winding turns, winding geometry, winding spacing, or winding arrangement, the equivalent inductance of the secondary winding can meet the impedance design requirements of the electromagnetic power frequency transformer 1 while matching the inductance value required for grid-side filtering of the filter circuit.

[0049] To further explain, the power electronic converter module 2 relies on the winding inductor integrated filter topology and works in conjunction with the electromagnetic power frequency transformer. Under the premise of having the basic functions of voltage transformation, power transmission and electrical isolation of traditional power transformers, it is adapted to the operating conditions of medium and low voltage distribution networks and realizes the functions of new energy grid connection, wide-range continuous voltage dynamic adjustment (±30%), grid reactive power compensation and distribution network three-phase imbalance management.

[0050] Specifically, the performance parameters of the power electronic converter module 2 can be determined first based on the rated capacity, primary rated voltage, secondary rated voltage, grid power frequency, and power quality control requirements of the hybrid transformer. Then, the filter circuit parameters are determined based on the performance parameters of the power electronic converter module 2, and the target inductance value required for grid-side filtering is obtained. Subsequently, the target inductance value is used as the design target for the equivalent inductance of the secondary winding, and the secondary winding is customized. Thus, while the secondary winding undertakes voltage transformation or power supply functions, its equivalent inductance can also serve as a component of the filter circuit, eliminating the need for an additional independent grid-side filter inductor.

[0051] Alternatively, in another embodiment of this application, combined with Figure 1 See Figure 2 The secondary winding W includes a first secondary winding W2 and a second secondary winding W3, and the filter circuit includes a first filter circuit FL1 and a second filter circuit FL2.

[0052] The first secondary winding W2 is electrically connected to the first filter circuit FL1, and the second secondary winding W3 is electrically connected to the second filter circuit FL2.

[0053] The first equivalent inductance L5 of the first secondary winding W2, together with the first filter capacitor C1 and the first converter-side filter inductance L2 in the first filter circuit FL1, form the first filter circuit.

[0054] The second equivalent inductance L6 of the second secondary winding W3, together with the second filter capacitor C2 and the second converter-side filter inductance L4 in the second filter circuit FL2, form the second filter circuit.

[0055] Specifically, the electromagnetic power frequency transformer 1 includes a primary winding W1, a first secondary winding W2, and a second secondary winding W3. The first secondary winding W2 and the second secondary winding W3 are electrically connected to the first filter circuit FL1 and the second filter circuit FL2, respectively.

[0056] It should be noted that the first secondary winding W2 and the second secondary winding W3 perform different electrical functions.

[0057] In some embodiments, the first secondary winding W2 is electrically connected to the load output terminal of the hybrid transformer for outputting electrical energy to the load side.

[0058] The second secondary winding W3 is electrically connected to the power supply terminal of the power electronic converter module 2, and is used to provide the corresponding power to the power electronic converter module 2.

[0059] At the same time, the first equivalent inductance L5 and the second equivalent inductance L6 participate in the first filter circuit and the second filter circuit respectively, thereby forming an integrated structure that combines functional partitioning of different secondary windings with multiplexing of equivalent winding inductance.

[0060] For example, the target inductance value of the grid-side filter corresponding to the first filter circuit can be used as the design target for the first equivalent inductance L5, and the target inductance value of the grid-side filter corresponding to the second filter circuit can be used as the design target for the second equivalent inductance L6. When the first equivalent inductance L5 and the second equivalent inductance L6 reach their respective target inductance values, a first high-order filter circuit can be formed by the first equivalent inductance L5, the first filter capacitor C1, and the first converter-side filter inductance L2, and a second high-order filter circuit can be formed by the second equivalent inductance L6, the second filter capacitor C2, and the second converter-side filter inductance L4. This reduces the number of independent filter components while maintaining filtering performance.

[0061] Specifically, the formula for calculating the filter inductance L2 on the first converter side is:

[0062]

[0063] Among them, U dc Here, f is the DC bus voltage of the first filter circuit, Δi is the ripple current of the first filter circuit, and f is the DC bus voltage of the first filter circuit. s This is the switching frequency of the power element in the first converter.

[0064] The formula for calculating the filter inductor L4 on the second converter side is:

[0065]

[0066] Among them, E n i is the rated voltage of the circuit. r f is the ripple current of the second filter circuit. sl This is the cutoff frequency of the second filter.

[0067] Based on the inductor reuse design: L1=L5, L3=L6.

[0068] Parameters of the first filter FL1:

[0069]

[0070]

[0071]

[0072]

[0073] Where L5 is the first equivalent inductance, L2 is the first converter-side filter inductance, K is the inductance scaling factor, and U 12 U is the percentage of the impedance voltage between the primary winding W1 and the first secondary winding W2. x2 S is the rated line voltage of the W2 winding.x2 This is the rated capacity of the W2 winding.

[0074] Parameters of the second filter FL2:

[0075]

[0076]

[0077] Among them, U x3 S is the rated line voltage of the W3 winding. x3 L3 is the rated capacity of the W3 winding, L6 is the second equivalent inductance, and L4 is the second converter-side filter inductance.

[0078] In one specific embodiment, the electromagnetic power frequency transformer 1 can be an oil-immersed transformer with a rated capacity of 200kVA, and the switching frequency of the power devices in the power electronic converter module 2 can be 40kHz. Based on the filtering requirements of the first filter circuit FL1, the first secondary winding W2 is designed to have a first equivalent inductance L5 of approximately 5μH under corresponding high-frequency operating conditions. The first filter capacitor C1 is set to 20μF, and the first converter-side filter inductance L2 is set to 20μH, so that the first filter circuit formed by these three components matches the switching frequency of the power devices to suppress harmonics generated by high-frequency switching operations. The above parameters are only one optional embodiment; the actual parameters can be adjusted according to the hybrid transformer capacity, voltage level, power device switching frequency, and filtering specifications.

[0079] Since the first secondary winding W2 and the second secondary winding W3 are connected to the filter circuit corresponding to the power electronic converter module 2, when the power electronic converter module 2 performs high-frequency power conversion, the first secondary winding W2 and the second secondary winding W3 may be subjected to high-frequency harmonic voltage and high-order harmonic current generated by the switching of power devices.

[0080] Therefore, in another embodiment of this application, the first secondary winding W2 and the second secondary winding W3 are respectively provided with an inter-turn insulation structure, an inter-layer insulation structure and a winding-to-ground insulation structure, wherein the inter-turn insulation structure, the inter-layer insulation structure and the winding-to-ground insulation structure are formed of insulating material.

[0081] Specifically, based on the inter-turn voltage, inter-layer voltage, and winding-to-ground voltage of the first secondary winding W2 and the second secondary winding W3 under high-frequency harmonic conditions, insulation withstand design can be performed on the inter-turn insulation structure, inter-layer insulation structure, and winding-to-ground insulation structure. The inter-turn electric field strength is adapted to the insulation withstand requirements under high-frequency harmonic conditions, avoiding insulation aging, partial discharge, and insulation breakdown, thus ensuring the long-term insulation reliability and electrical safety of the transformer. For example, insulation materials meeting the corresponding heat resistance requirements can be used, and the electric field strength between turns, between layers, and between windings and ground can be checked, thereby reducing the risk of insulation aging, partial discharge, or insulation breakdown under high-frequency harmonic conditions.

[0082] In some embodiments, the electromagnetic power frequency transformer includes a high-voltage winding, a low-voltage winding, and a winding cooling oil passage, wherein the winding cooling oil passage is disposed between the high-voltage winding and the low-voltage winding.

[0083] Since the equivalent inductance of the secondary winding is reused in the filter circuit, high-order harmonic currents may cause additional losses in the winding. Therefore, the heat dissipation capacity near the winding can be improved by setting up cooling oil channels in the winding, and a temperature rise margin should be reserved in combination with the core magnetic density design to accommodate the additional heat generated by high-frequency harmonic currents. See details in [link to relevant documentation]. Figure 3 The content shown.

[0084] For example, an axial winding cooling oil channel can be provided between the high-voltage winding and the low-voltage winding, and the working magnetic flux density of the core can be appropriately reduced to decrease core losses and reserve a temperature rise margin for additional heating of the winding. In one specific embodiment, the rated magnetic flux density of the core can be adjusted from 1.7T to 1.62T. After a temperature rise test, the heat dissipation design can be judged to meet the operating requirements based on the temperature rise of the top oil, the average temperature rise of the high-voltage winding, and the average temperature rise of the low-voltage winding.

[0085] In some embodiments, the power electronic converter module 2 includes power devices that are electrically connected to a filter circuit.

[0086] Specifically, the power devices are used to perform high-frequency power conversion and can work with the first and second filter circuits to regulate the output voltage. Because the power devices have a high switching frequency, the filter circuits can filter out the high-frequency harmonics generated by the switching action, thereby reducing the impact of high-frequency harmonics on the output power quality of the hybrid transformer.

[0087] In some embodiments, the power device can be a silicon carbide power device, and the specific configuration can be determined according to requirements.

[0088] In some embodiments, the power electronic converter module 2 is disposed outside the electromagnetic power frequency transformer 1 and is fixedly connected to the electromagnetic power frequency transformer 1.

[0089] It is understandable that the power electronic converter module adopts an integrated layout structure. By arranging the two parts adjacent to each other, an integrated whole structure can be formed in space while maintaining the relatively independent functional structure of the electromagnetic power frequency transformer 1 and the power electronic converter module 2. This reduces the space occupied by the split equipment and facilitates overall transportation, overall hoisting and on-site grid connection installation.

[0090] To further explain, the electromagnetic power frequency transformer 1 has reinforcing ribs on its outer side. The power electronic converter module 2 is fixedly connected to the reinforcing ribs by bolts. The AC output terminal of the power electronic converter module 2 is electrically connected to the lead-out terminal of the secondary winding via a copper busbar. For details, please refer to [link to relevant documentation]. Figure 4 The content shown.

[0091] For example, the power electronic converter module 2 can be mounted on the outside of the electromagnetic power frequency transformer 1 body, with the mechanical load of the power electronic converter module 2 supported by reinforcing ribs, and the electrical connection path between the power electronic converter module 2 and the secondary winding shortened by copper busbars.

[0092] In some embodiments, the hybrid transformer includes a voltage detection module and a controller. The voltage detection module is connected to the output voltage port of the hybrid transformer, the output of the voltage detection module is connected to the controller, and the controller is connected to the power electronic converter module 2.

[0093] Understandably, the voltage detection module is used to acquire the output voltage of the hybrid transformer in real time and send the corresponding detection signal to the controller. The controller generates a control signal for the power electronic converter module 2 based on the deviation between the output voltage and the preset output voltage, and uses the control signal to adjust the power conversion state of the power electronic converter module 2, thereby causing the output voltage of the hybrid transformer to approach and maintain the preset output voltage. For example, the preset output voltage can be 400V.

[0094] Furthermore, the controller can employ a closed-loop control method involving detection, analysis, and execution. The detection phase acquires the electrical parameters at the output of the hybrid transformer. The analysis phase determines, based on the electrical parameters, whether the current distribution network has power quality control requirements such as output voltage deviation, reactive power demand, or three-phase load imbalance. The execution phase generates control signals based on the power quality control requirements to control the power electronic converter module 2 to perform corresponding power conversion. Thus, in addition to voltage conversion and power transmission, the hybrid transformer can also perform output voltage regulation and power quality-related controls according to the application scenario.

[0095] This application provides a hybrid transformer comprising an electromagnetic power frequency transformer and a power electronic converter module. The electromagnetic power frequency transformer has a primary winding and at least one secondary winding. The power electronic converter module is electrically connected to the secondary winding and is equipped with a filter circuit. The filter circuit includes a filter capacitor and a converter-side filter inductor. The secondary winding is connected to the filter circuit, and the equivalent inductance of the secondary winding, the filter capacitor, and the converter-side filter inductor form a filter loop. The inductance value of the equivalent inductance matches the inductance value required for grid-side filtering in the filter circuit. Therefore, by connecting the secondary winding to the filter circuit, the equivalent inductance of the secondary winding, the filter capacitor, and the converter-side filter inductor form a filter loop, and the inductance value of the equivalent inductance matches the inductance value required for grid-side filtering, thus eliminating the need for a separate grid-side filter inductor and improving the integration of the hybrid transformer.

[0096] Corresponding to the hybrid transformer described above, this application also provides a method for regulating the output voltage of a hybrid transformer, such as... Figure 5 As shown, the specific steps include:

[0097] S501. Obtain the electrical parameters of the output terminal of the hybrid transformer, and determine the power quality control requirements based on the electrical parameters.

[0098] It is understandable that electrical parameters may include output voltage, and may also include at least one of output current, reactive power, or three-phase electrical quantities, depending on actual control requirements. The controller can obtain the output voltage through the voltage detection module and determine whether there is an output voltage adjustment requirement based on the deviation between the output voltage and the preset output voltage.

[0099] S502. Based on the power quality regulation requirements, generate control signals for the power electronic converter module, and control the power electronic converter module to perform power conversion based on the control signals in order to regulate the output voltage of the hybrid transformer.

[0100] Specifically, when the output voltage deviates from the preset output voltage, the controller determines the corresponding adjustment direction and amount based on the output voltage deviation and generates a control signal for the power electronic converter module. The power electronic converter module responds to the control signal by changing the power conversion state, causing the output voltage to adjust towards the preset output voltage.

[0101] S503. During the voltage regulation process of the power electronic converter module, the high-frequency harmonics generated by the power electronic converter module are filtered out through a filter circuit.

[0102] It should be noted that when the power electronic converter module performs high-frequency switching operations, the power devices will generate high-frequency harmonics. Since the equivalent inductance of the secondary winding is already used as the grid-side filter inductance of the filter circuit, the high-frequency harmonics can be attenuated sequentially through the filter circuit composed of the equivalent inductance, the filter capacitor, and the converter-side filter inductance, thus achieving high-frequency harmonic filtering without setting an independent grid-side filter inductor.

[0103] S504. After filtering is completed, obtain the output voltage of the regulated hybrid transformer output terminal.

[0104] Specifically, the voltage detection module continues to detect the output voltage port of the hybrid transformer and sends the adjusted output voltage to the controller, so that the controller can obtain the feedback result after this power conversion.

[0105] S505: Continue to control the power electronic converter module according to the output voltage to maintain the output voltage of the hybrid transformer at the preset output voltage.

[0106] Understandably, when the adjusted output voltage still deviates from the preset output voltage, the controller continues to adjust the control signal of the power electronic converter module 2 according to the output voltage deviation. When the output voltage reaches the corresponding allowable range, the controller maintains the current control state and continuously acquires new output voltages for feedback adjustment, thereby forming a closed-loop output voltage regulation process.

[0107] This application provides a method for regulating the output voltage of a hybrid transformer. By matching the equivalent inductance of the secondary winding with the inductance value required for grid-side filtering in the filter circuit, the equivalent inductance of the secondary winding itself is reused in the filter circuit. While ensuring the normal voltage transformation of the electromagnetic power frequency transformer and the high-frequency harmonic filtering function of the filter circuit, there is no need to set up an additional independent grid-side filter inductor, thereby reducing the number of filtering components and improving the integration of the hybrid transformer. Simultaneously, by strengthening the insulation structure of the secondary winding, setting up winding cooling oil channels, and fixing the power electronic converter module to the outside of the electromagnetic power frequency transformer, the operational reliability of the hybrid transformer under high-frequency harmonic conditions and the overall integration level can be further improved.

[0108] Those skilled in the art will further recognize that the units and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, computer software, or a combination of both. To clearly illustrate the interchangeability of hardware and software, the components and steps of the various examples have been generally described in terms of functionality in the foregoing description. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of this application.

[0109] The above description of the disclosed embodiments enables those skilled in the art to make or use this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A hybrid transformer, characterized in that, The hybrid transformer includes an electromagnetic power frequency transformer and a power electronic converter module; The electromagnetic power frequency transformer is provided with at least one secondary winding, and the power electronic converter module is electrically connected to the secondary winding. The power electronic converter module is equipped with a filter circuit, which includes a filter capacitor and a converter-side filter inductor. The secondary winding is connected to the filter circuit. The equivalent inductance of the secondary winding, together with the filter capacitor and the converter-side filter inductance, forms a filter loop. The inductance value of the equivalent inductance matches the inductance value required for the grid-side filtering of the filter circuit.

2. The hybrid transformer according to claim 1, characterized in that, The secondary winding includes a first secondary winding and a second secondary winding, and the filter circuit includes a first filter circuit and a second filter circuit. The first secondary winding is electrically connected to the first filter circuit, and the second secondary winding is electrically connected to the second filter circuit; The first equivalent inductance of the first secondary winding, together with the first filter capacitor and the first converter-side filter inductance in the first filter circuit, constitutes the first filter circuit. The second equivalent inductance of the second secondary winding, together with the second filter capacitor and the second converter-side filter inductance in the second filter circuit, constitute the second filter loop.

3. The hybrid transformer according to claim 2, characterized in that, The first secondary winding is electrically connected to the load output terminal of the hybrid transformer; The second secondary winding is electrically connected to the power supply terminal of the power electronic converter module.

4. The hybrid transformer according to claim 2, characterized in that, The first secondary winding and the second secondary winding are respectively provided with an inter-turn insulation structure, an inter-layer insulation structure and a winding-to-ground insulation structure, wherein the inter-turn insulation structure, the inter-layer insulation structure and the winding-to-ground insulation structure are formed of insulating material.

5. The hybrid transformer according to claim 1, characterized in that, The electromagnetic power frequency transformer includes a high-voltage winding, a low-voltage winding, and winding cooling oil channels; The winding cooling oil passage is located between the high-voltage winding and the low-voltage winding.

6. The hybrid transformer according to claim 1, characterized in that, The power electronic converter module includes power devices, which are electrically connected to the filter circuit.

7. The hybrid transformer according to claim 1, characterized in that, The power electronic converter module is located outside the electromagnetic power frequency transformer and is fixedly connected to the electromagnetic power frequency transformer.

8. The hybrid transformer according to claim 7, characterized in that, The electromagnetic power frequency transformer is provided with reinforcing ribs on its outer side. The power electronic converter module is fixedly connected to the reinforcing rib by bolts; The AC output terminal of the power electronic converter module is electrically connected to the lead-out terminal of the secondary winding via a copper busbar.

9. The hybrid transformer according to claim 1, characterized in that, The hybrid transformer includes a voltage detection module and a controller; The voltage detection module is connected to the output voltage port of the hybrid transformer, and the output terminal of the voltage detection module is connected to the controller; The controller is connected to the power electronic converter module.

10. A method for regulating the output voltage of a hybrid transformer, characterized in that, Applied to any one of the hybrid transformers described in claims 1-9, the output voltage regulation method includes: Obtain the electrical parameters of the output terminal of the hybrid transformer, and determine the power quality control requirements based on the electrical parameters; Based on the power quality control requirements, a control signal for the power electronic converter module is generated, and the power electronic converter module is controlled to perform power conversion based on the control signal to adjust the output voltage of the hybrid transformer; During the voltage regulation process of the power electronic converter module, the high-frequency harmonics generated by the power electronic converter module are filtered out through a filter circuit; After filtering is completed, the output voltage of the adjusted hybrid transformer output terminal is obtained; The power electronic converter module is further controlled based on the output voltage to maintain the output voltage of the hybrid transformer at a preset output voltage.

Images