An integrated magnetically controlled transformer system and its method for stabilizing output voltage
By using an integrated magnetically controlled transformer system with a grid-shaped iron core and a modularly designed AC/AC converter, grid disturbances can be offset in real time, solving the problems of response speed and accuracy of traditional transformers in grid voltage disturbances, and achieving efficient and reliable voltage stable output.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- GUANGDONG CHAMPON ELECTRIC CO LTD
- Filing Date
- 2026-01-23
- Publication Date
- 2026-06-02
AI Technical Summary
Traditional distribution transformers are slow to respond and have low regulation accuracy when faced with frequent and rapid grid voltage disturbances, making it difficult to meet high power quality requirements. They are also complex in structure and expensive.
An integrated magnetically controlled transformer system is adopted, including a main transformer, an auxiliary transformer, an AC/AC converter, and a controller. By sampling the output voltage of the main transformer in real time, a control signal is generated to drive the AC/AC converter to output an adjustable compensation voltage, which can offset grid disturbances in real time. Combined with the grid-shaped iron core and modular design, fast and accurate voltage stabilization is achieved.
It achieves fast response (within 10 milliseconds), high-precision (within 0.5%) voltage stability, compact structure, high reliability, optimized cost efficiency, and flexible system capacity expansion.
Smart Images
Figure CN122136902A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of power transformer technology, and more specifically, to an integrated magnetically controlled transformer system and a method for stabilizing its output voltage. Background Technology
[0002] In power distribution networks, grid voltage often fluctuates, dips, or spikes due to factors such as load switching, faults, and the integration of distributed energy sources. Traditional distribution transformers (main transformers), as passive components, directly transmit these disturbances from the high-voltage side to the low-voltage side, affecting the normal operation of sensitive loads. Existing voltage regulation devices, such as mechanical on-load tap changers, solid-state electronic voltage regulators, or contactless magnetically controlled voltage regulators, either have shortcomings in response speed, regulation accuracy, and service life, or are complex in structure and expensive. In particular, when dealing with frequent and rapid grid voltage disturbances, the dynamic performance of traditional solutions often fails to meet the requirements of high power quality. Therefore, there is an urgent need for a new voltage stabilization solution that offers rapid response, precise regulation, high reliability, and deep integration with the main transformer. Summary of the Invention
[0003] To overcome the shortcomings and deficiencies of the existing technology, the purpose of this invention is to provide an integrated magnetically controlled transformer system and its method for stabilizing output voltage; the system effectively isolates voltage disturbances on the grid side, ensures voltage stability on the load side, has a fast response speed, high voltage regulation accuracy, and a compact and reliable structure.
[0004] To achieve the above objectives, the present invention is implemented through the following technical solution: an integrated magnetically controlled transformer system, comprising a main transformer, an auxiliary transformer, one or more AC / AC converters, and a controller; The input terminal of the main transformer is connected to a high-voltage power grid with voltage fluctuations, and the output terminal provides a main voltage containing disturbance components. The primary side of the auxiliary transformer is connected to the output terminal of the AC / AC converter, and the secondary side is connected in series to the output circuit of the main transformer. The input terminal of the AC / AC converter is connected to the output side of the main transformer, and is used to directly convert the power source taken from the output side of the main transformer into a three-phase AC power with continuously adjustable amplitude and phase, so as to drive the auxiliary transformer to generate an adjustable compensation voltage. The controller samples the output voltage of the main transformer in real time and compares it with a set voltage value to generate a command signal for controlling the AC / AC converter. This allows the adjustable compensation voltage to cancel out the disturbance components in the main voltage in real time, thereby stabilizing the total output voltage after series superposition at the set voltage value.
[0005] Preferably, both the main transformer and the auxiliary transformer are mounted on a grid-shaped iron core; the three-phase high-voltage and low-voltage windings of the main transformer are wound on the three longitudinal core columns of the upper half of the grid-shaped iron core, respectively; the three-phase primary and secondary windings of the auxiliary transformer are wound on the three longitudinal core columns of the lower half of the grid-shaped iron core, respectively. This structure achieves a compact integration of the magnetic circuit and the electrical circuit, enhances magnetic coupling, and reduces leakage inductance and size.
[0006] Preferably, the width of the six longitudinal core columns in the upper and lower halves of the grid-shaped core is S0, the width of the transverse yoke at the top and bottom of the grid-shaped core is S0, and the width of the transverse yoke in the middle of the grid-shaped core is twice S0.
[0007] Preferably, the AC / AC converter adopts a matrix converter topology, comprising a switch array consisting of twelve bidirectional fully controlled switches, providing a three-phase input to three-phase output. This topology eliminates the need for DC energy storage, improving power density and system reliability.
[0008] Preferably, the system includes multiple AC / AC converters connected in parallel; the input terminals of all AC / AC converters are connected in parallel, and the output terminals are connected in parallel to jointly drive the auxiliary transformer; The controller includes a main controller and multiple module controllers corresponding one-to-one with each AC / AC converter. The main controller communicates with each module controller via a fiber optic synchronous bus. The module controllers control their respective AC / AC converters to achieve current sharing and redundant operation among the multiple AC / AC converters. This design enables flexible capacity expansion and high system reliability.
[0009] Preferably, the rated compensation capacity of the auxiliary transformer is in the range of 5% to 15% of the rated capacity of the main transformer, and the maximum compensation voltage of the auxiliary transformer is in the range of ±10% of the rated output voltage of the main transformer. This design optimizes cost and efficiency while ensuring sufficient compensation capacity.
[0010] A method for stabilizing output voltage, applied to the integrated magnetically controlled transformer system, includes: The output voltage of the main transformer is sampled in real time and used as the total output voltage feedback signal; The total output voltage feedback signal is compared with a set voltage value to obtain a voltage error signal; Based on the voltage error signal, the controller calculates the required total compensation current command. The total compensation current command is converted into a control signal for one or more AC / AC converters; The AC / AC converter is controlled to output a corresponding compensation voltage, which is superimposed in series with the disturbance voltage output by the main transformer to cancel the disturbance in real time and stabilize the final output voltage at the set voltage value.
[0011] Preferably, when calculating the compensation current command, a feedforward compensation amount based on the output voltage disturbance characteristics of the main transformer is introduced to improve the system's dynamic response speed and suppression accuracy to grid disturbances. The feedforward control acts in advance based on the detected disturbance, combined with feedback control, to achieve rapid and accurate voltage stabilization.
[0012] Preferably, when the integrated magnetically controlled transformer system includes multiple parallel AC / AC converters, and the controller includes a main controller and multiple module controllers corresponding one-to-one with the AC / AC converters, the method further includes: the main controller sends a synchronization clock signal to all module controllers through a synchronization optical fiber network, and dynamically allocates the total compensation current command to each module controller, and each module controller independently completes closed-loop tracking of the output current of the corresponding AC / AC converter to achieve current sharing and redundant operation.
[0013] Compared with the prior art, the present invention has the following advantages and beneficial effects: 1. Fast dynamic response: This invention adopts AC / AC direct conversion and feedforward-feedback composite control, which can shorten the response time to grid voltage disturbances to less than 10 milliseconds, far exceeding the traditional mechanical voltage regulation method; 2. High voltage regulation accuracy: Through closed-loop control and high-performance power electronic conversion, this invention can control the output voltage stability accuracy within 0.5%, meeting the requirements of highly sensitive loads; 3. Compact and reliable structure: This invention adopts a grid-shaped integrated iron core and modular design, which has a high degree of system integration and small size; it has no mechanical contacts, a long service life, and supports N+X redundancy, resulting in high operational reliability; 4. Efficiency and cost optimization: The auxiliary transformer of this invention only handles compensation power (5-15% of the main transformer capacity), the main power channel is highly efficient, the overall system loss is low, and the economy is good; 5. High scalability: The modular parallel AC / AC converter design of this invention allows the system capacity to be flexibly configured as needed, and is easy to maintain and upgrade. Attached Figure Description
[0014] Figure 1 This is a schematic diagram of the overall structure of the integrated magnetically controlled transformer system of the present invention; Figure 2 This is a schematic diagram of the structure of the main transformer and auxiliary transformer using a grid-shaped iron core in this invention; Figure 3 This is the circuit topology diagram of the AC / AC converter in this invention; Figure 4 This is a system control architecture diagram for the present invention when multiple AC / AC converters are connected in parallel. Detailed Implementation
[0015] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.
[0016] Example
[0017] like Figure 1 As shown, the integrated magnetically controlled transformer system in this embodiment includes a main transformer 2, an auxiliary transformer 4, an AC / AC converter 3, and a controller. The high-voltage side 1 of the main transformer 2 is connected to a 10kV fluctuating power grid, and the low-voltage side 5 outputs 380V, but this voltage contains disturbance components from the power grid. The primary side (380V side) of the auxiliary transformer 4 is connected to the output terminal of the AC / AC converter 3, and the secondary side (e.g., the 38V side) is connected to the low-voltage output circuit of the main transformer 2 via a series reactor (optional, used for current limiting). The input terminal of the AC / AC converter 3 is also connected to the 380V output side of the main transformer 2 to obtain its operating power. The controller samples the total output voltage of the system in real time (i.e., the voltage after the series superposition point), compares it with the internally set target value of 380V, and generates control signals such as PWM to drive the AC / AC converter 3.
[0018] like Figure 2 As shown, to optimize the magnetic circuit and reduce size, the main transformer 2 and the auxiliary transformer 4 share the same grid-shaped core 6. This grid-shaped core 6 consists of three transverse yokes at the top, middle, and bottom, and six longitudinal core columns located in the upper and lower halves. The three-phase high-voltage windings (A1, B1, C1) and low-voltage windings (A3, B3, C3) of the main transformer 2 are wound on the three longitudinal core columns in the upper half, respectively. The three-phase primary windings (A4, B4, C4) and secondary windings (A2, B2, C2) of the auxiliary transformer 4 are wound on the three longitudinal core columns in the lower half, respectively. This structure ensures tight coupling of the magnetic circuits of the main and auxiliary transformers, effectively reducing leakage reactance and improving the overall power density and response characteristics.
[0019] The essence of the grid-shaped iron core of this invention is to deeply integrate the magnetic circuits of two traditionally independent transformers (main transformer and auxiliary transformer) by sharing a yoke. The size ratio directly determines the "passage capacity" of the magnetic flux path. In this invention, the width of the six longitudinal iron core columns in the upper and lower halves of the grid-shaped iron core is S0, the width of the transverse yoke at the top and bottom of the grid-shaped iron core is S0, and the width of the transverse yoke in the middle of the grid-shaped iron core is twice S0. The principle is as follows: Vertical iron core columns: Each vertical iron core column is wound with windings of a specific phase (such as the high / low voltage windings of the main transformer of phase A, the primary / secondary windings of the auxiliary transformer of phase A). During operation, the phase flux of that phase flows through the vertical iron core column. The width of the vertical iron core column is calculated based on the ampere-turns of the winding of that phase and the maximum allowable magnetic flux density (magnetic density Bm) selected to ensure that the iron core column does not become magnetically saturated under rated load and certain overload conditions. The magnetic flux amplitudes of all six vertical columns are theoretically equal, so the same width S0 is adopted.
[0020] Top and bottom horizontal yokes (width S0): The top and bottom horizontal yokes form a path for the transverse closure of the magnetic flux. The key point is that in the "field" structure, the top horizontal yoke only carries the magnetic flux of the upper half of the three vertical iron core columns (main transformer part), and the bottom horizontal yoke only carries the magnetic flux of the lower half of the three vertical iron core columns (auxiliary transformer part). At any cross-section, the top and bottom horizontal yokes essentially only collect and conduct the magnetic flux of a single phase (because the three-phase magnetic fluxes differ by 120° in space, and theoretically the vector sum in the iron yoke is zero, but in the actual path, the magnetic fluxes of each phase alternate). Since the magnetic flux flowing through the top and bottom horizontal yokes is of the same order as that of a single vertical iron core column, their width is also designed as S0 to maintain a magnetic density level similar to that of the vertical columns and avoid becoming a bottleneck in the magnetic circuit.
[0021] Middle horizontal yoke: The middle horizontal yoke is the only magnetic path bridge connecting the upper half (main transformer magnetic path) and the lower half (auxiliary transformer magnetic path). It needs to carry the magnetic fluxes from the three vertical iron core columns above and the three vertical iron core columns below at the same time. The magnetomotive force of the three-phase windings of the main transformer generates the main magnetic flux in its magnetic path (upper half + middle horizontal yoke); the magnetomotive force of the three-phase windings of the auxiliary transformer generates the control magnetic flux in its magnetic path (lower half + middle horizontal yoke). These two sets of magnetic fluxes are vectorially superimposed or cancelled at the middle horizontal yoke, thus realizing magnetic control voltage regulation. Therefore, the instantaneous magnetic flux in the middle horizontal yoke may reach several times that of a single vertical iron core column. Designing the width of the middle horizontal yoke as 2S0 is precisely to provide sufficient "channels" for this complex magnetic flux collection and interaction, preventing the middle horizontal yoke from becoming the weakest point most prone to saturation in the entire magnetic circuit due to insufficient cross-sectional area.
[0022] In summary, the "field"-shaped iron core of the present invention has the following advantages: (1) Magnetic circuit balance and optimal performance: This size ratio ensures that the magnetic flux density of all paths from the vertical iron core column to the horizontal yoke is at a reasonable and similar level, maximizing the utilization of the iron core material and achieving low loss, low heat generation, and high efficiency; (2) Structural strength and processability: The uniform and symmetrical size design is beneficial to the lamination, clamping, and overall mechanical strength guarantee of the iron core; (3) Achieving deep integration: The middle horizontal yoke adopts a strengthened design, allowing the main and auxiliary transformer magnetic paths to be safely and efficiently coupled together, which is the physical basis for realizing the "integrated" and "magnetic control" functions.
[0023] like Figure 3 As shown, the AC / AC converter adopts a three-phase matrix converter topology. It includes three-phase input terminals connected to input LCL filters (L1-L6, C1-C3), followed by a 3×4 switch array consisting of twelve bidirectional fully controlled transistors (Q1-Q12, which can be IGBTs and diodes in anti-parallel). The output LC filters (L7-L9, C5-C7) then connect to the primary side of the auxiliary transformer. By controlling the duty cycle of these twelve transistors using algorithms such as Space Vector Modulation (SVM), the input three-phase 380V fixed AC power can be directly converted into a continuously adjustable three-phase AC output with adjustable amplitude (e.g., 0-38V adjustable) and phase (can be in phase or out of phase with the main voltage), without the need for an intermediate DC link.
[0024] like Figure 4 As mentioned above, when the system requires a larger compensation capacity or higher reliability, multiple AC / AC converters 3 can be connected in parallel. The input terminals of all AC / AC converters 3 are connected in parallel to the output side of the main transformer, and the output terminals are connected in parallel to jointly drive the primary side of the auxiliary transformer 4.
[0025] The controller adopts a distributed architecture, including a main controller and module controllers corresponding to each AC / AC converter. Each module controller and its corresponding AC / AC converter constitute a module. The main controller is responsible for system-level tasks: acquiring the total output voltage, running the voltage outer loop algorithm, and calculating the total compensation current command I*. total And through a high-speed fiber optic synchronization network, the synchronization clock signal and the allocated current command I* are transmitted. module_i The command is sent to each module controller. Each module controller (typically integrating a DSP and FPGA) receives the command and samples its own output current I using its Hall sensor. out_i High-speed current inner-loop control (such as proportional resonant control) generates PWM drive signals for the switching transistors of this module, achieving precise current tracking and automatic current sharing among modules. The main controller continuously monitors the status of each module. If a module fails, it can be immediately shut down, and instructions can be reallocated to the remaining modules to achieve redundant and uninterrupted operation.
[0026] The specific steps of the method for stabilizing output voltage according to the present invention are as follows: S1: Real-time sampled total output voltage U after series superposition out ; S2: Convert the total output voltage U out With the set voltage value U ref (e.g., 380V) Compare to obtain the voltage error e; S3: The voltage error e passes through the outer voltage loop PI controller to generate a basic feedback compensation current command I*.fb ; S4 (Optional Enhancement Step): To improve dynamic performance, the voltage U on the output side of the main transformer is sampled simultaneously. in (Including disturbances), the disturbance component U is quickly extracted using the disturbance observer algorithm. disturb And calculate the feedforward compensation current command I* ff ; The feedforward compensation current command I* ff The specific generation method is as follows: real-time sampling of the voltage U on the output side of the main transformer. A ;Change U A Combined with the equivalent mathematical model of the AC / AC converter and auxiliary transformer; for example: a frequency-locked loop disturbance observer based on a second-order generalized integrator, the fundamental positive-sequence component and the disturbance component U can be quickly separated. disturb Then, based on the turns ratio of the auxiliary transformer and the impedance characteristics of the series connection point, the feedforward current command I* required to directly cancel the disturbance component is calculated. ff In particular, the observer model considers the total system delay from the disturbance input point to the compensation voltage output point to achieve advance compensation and overcome the system inertia caused by energy extraction from the disturbance side; S5: Synthetic total compensation current command I* total =I∗ fb +I∗ ff ; S6: For a single AC / AC converter system, directly use I* total Converted into a control signal; in the case of a system with multiple AC / AC converters, the main controller will convert I* total Instructions I* are allocated to each module according to a strategy (such as average allocation). module_i And it is distributed via fiber optic network; S7: Each AC / AC converter operates local current closed-loop control according to the received current command and outputs the corresponding compensation voltage; S8: This compensation voltage is induced to the secondary side through the auxiliary transformer, and superimposed on the main voltage vector to cancel out the disturbance component in real time, ultimately making U out Stable at U ref .
[0027] Taking a 10kV / 380V, 200kVA main transformer as an example. To compensate for ±10% voltage fluctuations, the auxiliary transformer is designed to be 380V / 38V, with a capacity of 10% of the main transformer capacity, i.e., 20kVA. The capacity of a single AC / AC converter module can be set to 10kVA as needed, and two modules connected in parallel can meet the 20kVA requirement, achieving 1+1 redundancy. The controller sampling frequency is set to 10kHz, the switching frequency is set to 10kHz, and the current loop control cycle is 100μs. Through these parameter designs, the system can achieve a voltage regulation range of ±10%, a steady-state accuracy better than 0.5%, and a step disturbance response time of less than 10ms.
[0028] This invention effectively solves the problem of actively and quickly stabilizing the voltage of the power distribution network by combining the above-mentioned integrated structure, advanced topology and intelligent control method.
[0029] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.
Claims
1. An integrated magnetically controlled transformer system, characterized in that: Includes a main transformer, an auxiliary transformer, one or more AC / AC converters, and a controller; The input terminal of the main transformer is connected to a high-voltage power grid with voltage fluctuations, and the output terminal provides a main voltage containing disturbance components. The primary side of the auxiliary transformer is connected to the output terminal of the AC / AC converter, and the secondary side is connected in series to the output circuit of the main transformer. The input terminal of the AC / AC converter is connected to the output side of the main transformer, and is used to directly convert the power source taken from the output side of the main transformer into a three-phase AC power with continuously adjustable amplitude and phase, so as to drive the auxiliary transformer to generate an adjustable compensation voltage. The controller samples the output voltage of the main transformer in real time and compares it with a set voltage value to generate a command signal for controlling the AC / AC converter. This allows the adjustable compensation voltage to cancel out the disturbance components in the main voltage in real time, thereby stabilizing the total output voltage after series superposition at the set voltage value.
2. The integrated magnetically controlled transformer system according to claim 1, characterized in that: Both the main transformer and the auxiliary transformer are mounted on a grid-shaped iron core. The three-phase high and low voltage windings of the main transformer are wound on the three longitudinal iron core columns in the upper half of the grid-shaped iron core, respectively. The three-phase primary and secondary windings of the auxiliary transformer are wound on the three longitudinal iron core columns in the lower half of the grid-shaped iron core, respectively.
3. The integrated magnetically controlled transformer system according to claim 1, characterized in that: The width of the six longitudinal core columns in the upper and lower halves of the grid-shaped core is S0, the width of the transverse yoke at the top and bottom of the grid-shaped core is S0, and the width of the transverse yoke in the middle of the grid-shaped core is twice S0.
4. The integrated magnetically controlled transformer system according to claim 1, characterized in that: The AC / AC converter adopts a matrix converter topology, which includes a switch array consisting of twelve bidirectional fully controlled switches, providing a three-phase input to a three-phase output.
5. The integrated magnetically controlled transformer system according to claim 1, characterized in that: The system includes multiple AC / AC converters connected in parallel; the inputs of all AC / AC converters are connected in parallel, and the outputs are connected in parallel to jointly drive the auxiliary transformer. The controller includes a main controller and multiple module controllers corresponding to each AC / AC converter. The main controller communicates with each module controller via a fiber optic synchronous bus. The module controllers control their corresponding AC / AC converters to achieve current sharing and redundant operation among the multiple AC / AC converters.
6. The integrated magnetically controlled transformer system according to claim 1, characterized in that: The rated compensation capacity of the auxiliary transformer is 5% to 15% of the rated capacity of the main transformer, and the maximum compensation voltage of the auxiliary transformer is ±10% of the rated output voltage of the main transformer.
7. A method for stabilizing output voltage, applied to the integrated magnetically controlled transformer system of claim 1, characterized in that: include: The output voltage of the main transformer is sampled in real time and used as the total output voltage feedback signal; The total output voltage feedback signal is compared with a set voltage value to obtain a voltage error signal; Based on the voltage error signal, the controller calculates the required total compensation current command. The total compensation current command is converted into a control signal for one or more AC / AC converters; The AC / AC converter is controlled to output a corresponding compensation voltage, which is superimposed in series with the disturbance voltage output by the main transformer to cancel the disturbance in real time and stabilize the final output voltage at the set voltage value.
8. The method for stabilizing output voltage according to claim 7, characterized in that: When calculating the compensation current command, a feedforward compensation amount based on the output voltage disturbance characteristics of the main transformer is introduced to improve the system's dynamic response speed and suppression accuracy to grid disturbances.
9. The method for stabilizing output voltage according to claim 7, characterized in that: When the integrated magnetically controlled transformer system includes multiple parallel AC / AC converters, and the controller includes a main controller and multiple module controllers corresponding one-to-one with the AC / AC converters, the method further includes: the main controller sends a synchronization clock signal to all module controllers through a synchronization optical fiber network, and dynamically allocates the total compensation current command to each module controller. Each module controller independently completes closed-loop tracking of the output current of the corresponding AC / AC converter to achieve current sharing and redundant operation.