Power electronic transformer and method of operation control and non-volatile storage medium

Abstract

The application discloses a power electronic transformer, an operation control method and a nonvolatile storage medium. The power electronic transformer comprises a line compensation device and a hybrid module. The input end of the line compensation device is connected with a power grid side. The output end of the line compensation device is correspondingly connected with the input end of the hybrid module. The output end of the hybrid module is connected to a load side through a bypass module. The line compensation device comprises a series capacitor, a thyristor protection unit, a bypass mechanical switch and a series reactor. The series capacitor, the thyristor protection unit and the bypass mechanical switch are connected in parallel to form a parallel branch. The parallel branch is connected in series with the series reactor. The hybrid module comprises an input transformer, an AC / DC rectification unit, a DC / AC inversion unit and an output filter unit. The application solves the technical problem that the current end treatment device is insufficient in suppressing the voltage drop of a line side.

Description

Technical Field

[0001] This invention relates to the field of power electronics technology, and more specifically, to a power electronic transformer and its operation control method, as well as a non-volatile storage medium. Background Technology

[0002] In the current power distribution network, the mainstream solutions for voltage fluctuations, low voltage, and voltage flicker mainly fall into two categories: First, end-point voltage management devices, which achieve dynamic voltage compensation through hybrid converter modules (AC / DC-DC / AC converter units), can quickly respond to load-side voltage changes and have a direct effect on end-point voltage deviation and sag; Second, line-side reactive power compensation devices, which compensate for line reactive power through parallel capacitors or reactors, reducing line voltage drop caused by reactive current.

[0003] In the aforementioned technologies, traditional voltage management devices only compensate for voltage on the load side and do not intervene in the impedance voltage drop of the line itself, resulting in insufficient suppression of voltage drop on the line side. For long-distance distribution network lines, voltage loss caused by line impedance (especially the inductive component) increases significantly with the increase of load current, limiting the compensation effect. In addition, existing solutions cannot effectively suppress voltage flicker caused by the start-up of inductive loads. When inductive loads such as high-power motors at the end of the line start, short-term inrush current will generate a large voltage drop across the line impedance. Existing parallel reactive power compensation devices have slow response speeds and cannot match the millisecond-level inrush of motor start-up. The end-of-line management devices can only passively compensate for voltage deviations and cannot reduce the impact of inrush current on line voltage. At the same time, to compensate for line voltage drop and voltage fluctuations of inrush loads, existing end-of-line management devices need to be configured with larger compensation capacity, increasing equipment cost, size, and losses. Moreover, they cannot adapt to the differentiated scenarios of different line impedances, highlighting the contradiction between management cost and capacity.

[0004] There is currently no effective solution to the above problems. Summary of the Invention

[0005] This invention provides a power electronic transformer and its operation control method, as well as a non-volatile storage medium, to at least solve the technical problem of insufficient suppression of line-side voltage drop in current end-of-line treatment devices.

[0006] According to one aspect of the present invention, a power electronic transformer is provided, comprising: an input terminal of a line compensation device connected to the grid side, an output terminal of the line compensation device correspondingly connected to the input terminal of a hybrid transformer module, and an output terminal of the hybrid transformer module connected to the load side via a bypass module; the line compensation device includes a series capacitor, a thyristor protection unit, a bypass mechanical switch, and a series reactor, wherein the series capacitor, the thyristor protection unit, and the bypass mechanical switch are connected in parallel to form a parallel branch, and the parallel branch is connected in series with the series reactor; the hybrid transformer module includes an input transformer, an AC / DC rectifier unit, a DC / AC inverter unit, and an output filter unit, wherein the primary side of the input transformer is connected to the output terminal of the line compensation device, the secondary side of the input transformer is connected to the input terminal of the AC / DC rectifier unit, the DC side of the AC / DC rectifier unit is connected to the DC side of the DC / AC inverter unit, the output terminal of the DC / AC inverter unit is connected to the output filter unit, and the output filter unit is connected to the bypass module.

[0007] Optionally, the thyristor protection unit adopts an anti-parallel thyristor structure.

[0008] Optionally, the AC / DC rectifier unit is a three-phase PWM rectifier; the DC / AC inverter unit is a three-phase PWM inverter; and the output filter unit includes an LC filter, wherein the LC filter includes a filter inductor and a filter capacitor.

[0009] Optionally, the bypass module includes a bypass switch and a series reactor branch, wherein: the bypass switch and the series reactor branch are connected in parallel; one end of the bypass module is connected to the output end of the hybrid transformer module, and the other end is connected to the load side.

[0010] According to another aspect of the present invention, an operation control method for a power electronic transformer is also provided, for controlling any of the aforementioned power electronic transformers, including: real-time monitoring of the voltage and current on the grid side and the voltage and current on the load side; determining the operating mode of the power electronic transformer as a normal operating mode when the voltage and current on the grid side and the voltage and current on the load side are both within their respective safety ranges; controlling the bypass mechanical switch in the power electronic transformer to open, the thyristor protection unit to turn off, and the bypass switch to open when the operating mode is normal operating mode; offsetting the line inductive impedance through the series capacitor in the power electronic transformer and maintaining the voltage on the load side within the corresponding safety range through the DC / AC inverter unit in the power electronic transformer.

[0011] Optionally, the peak current is determined based on the load-side current; if the peak current exceeds a preset current threshold, the operating mode of the power electronic transformer is determined to be the impact load mitigation mode; if the operating mode is the impact load mitigation mode, the predicted voltage drop is calculated based on the peak current; and the output voltage of the DC / AC inverter unit in the power electronic transformer is adjusted based on the predicted voltage drop.

[0012] Optionally, if an abnormality is detected in the line compensation device of the power electronic transformer, the operating mode of the power electronic transformer is determined to be fault / maintenance mode; when the operating mode is fault / maintenance mode, the thyristor protection unit in the power electronic transformer is turned on or the bypass mechanical switch is closed.

[0013] Optionally, if an abnormality is detected in the hybrid module of the power electronic transformer, the operating mode of the power electronic transformer is determined to be fault / maintenance mode; in the fault / maintenance mode, the PWM pulse of the DC / AC inverter unit in the power electronic transformer is blocked; and the bypass switch in the power electronic transformer is controlled to close.

[0014] According to another aspect of the present invention, a non-volatile storage medium is also provided, the non-volatile storage medium including a stored program, wherein, when the program is running, the device where the non-volatile storage medium is located is controlled to execute any of the above-described power electronic transformer operation control methods.

[0015] According to another aspect of the present invention, a computer device is also provided, the computer device including a processor, the processor being configured to run a program, wherein the program, when running, executes any of the above-described power electronic transformer operation control methods.

[0016] According to another aspect of the present invention, a computer program product is also provided, including a computer program that, when executed by a processor, implements any of the above-described methods for controlling the operation of a power electronic transformer.

[0017] In this embodiment of the invention, the power electronic transformer includes: an input terminal of a line compensation device connected to the grid side, an output terminal of the line compensation device correspondingly connected to the input terminal of a hybrid power conversion module, and an output terminal of the hybrid power conversion module connected to the load side via a bypass module; the line compensation device includes a series capacitor, a thyristor protection unit, a bypass mechanical switch, and a series reactor, wherein the series capacitor, thyristor protection unit, and bypass mechanical switch are connected in parallel to form a parallel branch, and the parallel branch is connected in series with the series reactor; the hybrid power conversion module includes an input transformer, an AC / DC rectifier unit, a DC / AC inverter unit, and an output filter unit, wherein the primary side of the input transformer is connected to the output of the line compensation device. The secondary side of the input transformer is connected to the input terminal of the AC / DC rectifier unit, the DC side of the AC / DC rectifier unit is connected to the DC side of the DC / AC inverter unit, the output terminal of the DC / AC inverter unit is connected to the output filter unit, and the output filter unit is connected to the bypass module. This effectively suppresses voltage flicker during inductive load startup. The series capacitor can quickly respond to changes in line current, offset the voltage drop of the inrush current on the line impedance, and significantly reduce the voltage fluctuation amplitude in scenarios such as motor startup. This achieves the technical effect of reducing line voltage drop from the source and improving the efficiency of the treatment device, thereby solving the technical problem of insufficient suppression of line-side voltage drop by current end-of-line treatment devices. Attached Figure Description

[0018] The accompanying drawings, which are included to provide a further understanding of the invention and form part of this application, illustrate exemplary embodiments of the invention and, together with their description, serve to explain the invention and do not constitute an undue limitation thereof. In the drawings:

[0019] Figure 1 A hardware structure block diagram of a computer terminal for implementing an operation control method for a power electronic transformer is shown.

[0020] Figure 2 This is a structural block diagram of a power electronic transformer provided according to an embodiment of the present invention;

[0021] Figure 3 This is a flowchart illustrating the operation control method for a power electronic transformer according to an embodiment of the present invention. Detailed Implementation

[0022] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0023] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of the invention described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover a non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0024] According to an embodiment of the present invention, a method embodiment of an operation control method for a power electronic transformer is provided. It should be noted that the steps shown in the flowchart in the accompanying drawings can be executed in a computer system such as a set of computer-executable instructions. Furthermore, although a logical order is shown in the flowchart, in some cases, the steps shown or described may be executed in a different order than that shown here.

[0025] The methods and embodiments provided in this application can be executed on mobile terminals, computer terminals, or similar computing devices. Figure 1 A hardware block diagram of a computer terminal for implementing an operation control method for a power electronic transformer is shown. Figure 1 As shown, the computer terminal 10 may include one or more processors (shown as 102a, 102b, ..., 102n in the figure) (the processor may include, but is not limited to, a microprocessor MCU or a programmable logic device FPGA, etc.) and a memory 104 for storing data. In addition, it may also include: a display, an input / output interface (I / O interface), a universal serial bus (USB) port (which may be included as one of the ports of a BUS bus), a network interface, a power supply, and / or a camera. Those skilled in the art will understand that... Figure 1 The structure shown is for illustrative purposes only and does not limit the structure of the aforementioned electronic device. For example, computer terminal 10 may also include... Figure 1 The more or fewer components shown, or having the same Figure 1 The different configurations shown.

[0026] It should be noted that the aforementioned one or more processors and / or other data processing circuits are generally referred to herein as "data processing circuits". These data processing circuits may be embodied, in whole or in part, in software, hardware, firmware, or any other combination thereof. Furthermore, the data processing circuits may be a single, independent processing module, or may be integrated, in whole or in part, into any other element within the computer terminal 10. As involved in the embodiments of this application, the data processing circuits serve as a processor control mechanism (e.g., selection of a variable resistor termination path connected to an interface).

[0027] The memory 104 can be used to store software programs and modules of application software, such as the program instructions / data storage device corresponding to the operation control method of the power electronic transformer in this embodiment of the invention. The processor executes various functional applications and data processing by running the software programs and modules stored in the memory 104, thereby implementing the above-mentioned application program for the operation control method of the power electronic transformer. The memory 104 may include high-speed random access memory, and may also include non-volatile memory, such as one or more magnetic storage devices, flash memory, or other non-volatile solid-state memory. In some instances, the memory 104 may further include memory remotely located relative to the processor, and these remote memories can be connected to the computer terminal 10 via a network. Examples of such networks include, but are not limited to, the Internet, corporate intranets, local area networks, mobile communication networks, and combinations thereof.

[0028] The display can be, for example, a touchscreen liquid crystal display (LCD) that allows the user to interact with the user interface of the computer terminal 10.

[0029] Figure 2 This is a structural block diagram of a power electronic transformer provided according to an embodiment of the present invention, such as... Figure 2As shown, the line compensation device includes a series capacitor C1, a thyristor protection unit S1, a bypass mechanical switch K1, and a series reactor L1. The series capacitor, thyristor protection unit, and bypass mechanical switch are connected in parallel to form a parallel branch, which is connected in series with the series reactor. The hybrid module includes an input transformer TR1, an AC / DC rectifier unit (including a TR2 energy extraction winding), a DC / AC inverter unit (including a TR3 voltage regulating winding), and an output filter unit. The power electronic transformer includes: the input terminal of the line compensation device is connected to the grid side; the output terminal of the line compensation device is connected to the corresponding input terminal of the hybrid module; and the output terminal of the hybrid module is connected to the load side through a bypass module. The primary side of the input transformer is connected to the output terminal of the line compensation device; the secondary side of the input transformer is connected to the input terminal of the AC / DC rectifier unit; the DC side of the AC / DC rectifier unit is connected to the DC side of the DC / AC inverter unit; the output terminal of the DC / AC inverter unit is connected to the output filter unit; and the output filter unit is connected to the bypass module.

[0030] The grid-side lines are first connected to a line compensation device. The output of the line compensation device is connected to the input of the hybrid transformer module. The output of the hybrid transformer module is connected to the load-side unit through a bypass module. Through the coordinated work of each unit, the voltage management function of the distribution network lines is finally realized, ensuring stable voltage and qualified waveform on the load side. This modular structure design not only facilitates the installation, inspection, and maintenance of the device, but also allows for flexible adjustment of the parameters of each module according to the actual operating conditions of the distribution network, improving the adaptability and scalability of the device.

[0031] The line compensation device is the core front-end unit of this invention for suppressing voltage drop and stabilizing voltage in distribution network lines. It is mainly used to offset the inductive impedance of the lines and alleviate voltage flicker. Its structure, connection method and working principle are as follows:

[0032] Structural Composition: The core of this device includes a series capacitor, a thyristor protection unit (using an anti-parallel thyristor structure), a bypass mechanical switch, and a series reactor. These components work together to form the core circuit for line compensation. The anti-parallel thyristor serves as a fast protection actuator, the bypass mechanical switch serves as a backup protection and maintenance auxiliary device, and the series reactor is used to suppress current surges.

[0033] The series capacitor provides capacitive impedance to offset the inductive impedance of the line. The thyristor protection unit uses an anti-parallel thyristor structure as a fast protection actuator with a response time in the microsecond range. The bypass mechanical switch, such as an AC contactor or circuit breaker, serves as a backup protection and maintenance auxiliary device; its operating speed is relatively slow, but it has strong current-carrying capacity and no losses.

[0034] Connection method: A composite connection method of "parallel + series" is adopted. Specifically, the series capacitor, the thyristor protection unit, and the bypass mechanical switch are connected in parallel to form a parallel branch. This parallel branch is then connected in series with the series reactor, and the whole is connected in series in the grid-side line to ensure that the line current can flow through the series reactor and the parallel branch in sequence, so as to achieve the synergistic effect of compensation and protection.

[0035] Working Principle: When the device is in normal operation, the bypass mechanical switch is open, and the line current mainly flows through the series capacitor. The series capacitor uses its capacitive impedance to offset the inherent inductive impedance of the distribution network line, thereby reducing the line voltage drop, increasing the voltage level at the end of the line, and ensuring voltage stability. When abnormal conditions such as overvoltage or fault current occur in the line, the anti-parallel thyristor of the thyristor protection unit will quickly conduct (response time is on the order of microseconds), short-circuiting the series capacitor to prevent it from being damaged by overvoltage or overcurrent impacts, thus providing rapid protection. After the fault is cleared, the thyristor protection unit turns off, the series capacitor is reconnected to the line, and the device resumes its normal series compensation function. In addition, when the device needs maintenance or long-term shutdown, the bypass mechanical switch can be closed to allow the line current to flow directly through the bypass mechanical switch, achieving uncompensated operation of the line, ensuring the continuity of power supply to the distribution network, and avoiding load outages due to device maintenance.

[0036] The hybrid converter module is the core conversion unit of this invention for achieving precise voltage adjustment and power quality optimization. It is mainly used to convert the voltage after line compensation into a stable AC voltage that meets the requirements of the load side. Its structure, connection method and working principle are as follows:

[0037] Structural composition: The core consists of an input transformer, an AC / DC rectifier unit, a DC / AC inverter unit, and an output filter unit. Each unit works in sequence to achieve power isolation, rectification, inversion, and filtering, ensuring that the output voltage waveform is qualified and the amplitude is stable.

[0038] Connection method: The components are connected sequentially. The primary side of the input transformer is connected to the output terminal of the line compensation device to receive the AC voltage after line compensation. The secondary side of the input transformer is connected to the input terminal of the AC / DC rectifier unit to achieve electrical isolation and preliminary voltage matching. The DC side of the AC / DC rectifier unit is connected to the DC side of the DC / AC inverter unit to transmit the rectified stable DC voltage. The output side of the DC / AC inverter unit is connected to the output filter unit, and the filtered voltage is finally output to the bypass module.

[0039] Working Principle: The AC voltage, compensated by the line compensation device, first enters the input transformer. The input transformer serves two purposes: firstly, it provides electrical isolation between the line compensation device and the subsequent power electronic modules, preventing electromagnetic interference between modules and protecting the safety of downstream devices; secondly, it performs preliminary adaptation and transformation of the input voltage, outputting an AC voltage that meets the input requirements of the AC / DC rectifier unit. This AC voltage is then input to the AC / DC rectifier unit, which performs rectification, converting the AC voltage into a stable DC voltage. This provides a stable DC input for the subsequent DC / AC inverter unit, ensuring the stability of the inverter process. The DC / AC inverter unit, based on the real-time voltage demand of the load side, inverts the input DC voltage into an AC voltage with stable amplitude and frequency, adapting to the load's power requirements. Finally, the output filter unit filters out harmonics generated during the inverter process, eliminating harmonic interference, ensuring the quality of the load-side voltage waveform, and preventing harmonics from damaging the electrical load.

[0040] The bypass module is the core redundant unit of this invention for improving power supply reliability. It is mainly used to ensure continuous power supply to the load side when the hybrid transformer module fails or is under maintenance. Its structure, connection method and working principle are as follows:

[0041] Structural composition: The core consists of a bypass switch and a series reactor branch, which together form a bypass circuit. The series reactor branch is used to suppress the current surge during bypass switching, and the bypass switch is used to control the on / off state of the bypass circuit.

[0042] Connection method: The bypass switch and the series reactor branch are connected in parallel. One end of the parallel circuit is connected to the output side of the hybrid transformer module, and the other end is connected to the load side unit, forming a parallel redundant structure of the hybrid transformer module and the bypass module, ensuring that if any module fails, the other module can quickly take over.

[0043] Working principle: When the device is operating normally, the bypass switch is in the open state, and the stable voltage output by the hybrid transformer module is transmitted to the load side through the series reactor branch of the bypass module (at which time no current flows). When the hybrid transformer module fails (such as the AC / DC rectifier unit or DC / AC inverter unit fails) or needs maintenance, the control unit immediately triggers the bypass switch to close, and the line current flows directly through the bypass switch of the bypass module, bypassing the faulty or maintenance-needed hybrid transformer module, and directly supplying power to the load side, realizing uninterrupted maintenance of the device, greatly improving the power supply reliability of the distribution network, and avoiding load power outages due to hybrid transformer module failures.

[0044] By using series capacitors to compensate for the inductive impedance of the line, the inductive voltage drop of the line is offset, the transmission loss of the line is reduced, the compensation capacity requirement of the downstream hybrid power conversion module is lowered, and the overall efficiency of the device is improved. Furthermore, the series capacitors can quickly respond to changes in line current, offsetting the voltage drop across the line impedance caused by inrush current, significantly reducing voltage fluctuations in scenarios such as motor startup, and solving the lag problem of passive compensation in end-of-pipe treatment devices.

[0045] The line compensation device integrates a thyristor protection unit and a bypass mechanical switch, which can quickly disconnect the capacitor in case of a fault to avoid overvoltage damage and ensure the safe operation of the device and the power grid. The existence of the bypass module allows the load side to still be directly powered through the bypass when the hybrid transformer module fails or is under maintenance, realizing uninterrupted maintenance and significantly improving the reliability of the power distribution network.

[0046] As an optional embodiment, the thyristor protection unit adopts an anti-parallel thyristor structure.

[0047] Optionally, the thyristor protection unit adopts an anti-parallel thyristor structure, specifically, two thyristors are connected in reverse parallel with anode to cathode and cathode to anode, giving it bidirectional conduction capability. When overvoltage or fault current occurs on the line side, this structure can quickly trigger conduction according to the voltage polarity, thereby short-circuiting the series capacitor within microseconds. Compared with traditional unidirectional conduction or slow response protection methods, this significantly improves the timeliness and reliability of protection action, effectively avoids damage to the series capacitor due to overvoltage and overcurrent impacts, and ensures the safe operation of the power electronic transformer under abnormal grid conditions.

[0048] As an optional embodiment, the AC / DC rectifier unit is a three-phase PWM rectifier; the DC / AC inverter unit is a three-phase PWM inverter; and the output filter unit includes an LC filter, wherein the LC filter includes a filter inductor and a filter capacitor.

[0049] Optionally, the AC / DC rectifier unit is a three-phase PWM rectifier, which uses pulse width modulation technology to controllably rectify AC power from the grid. Compared with traditional uncontrolled rectification, this structure can adjust the phase and amplitude of the input current, achieve unity power factor operation, and suppress input harmonics. The DC / AC inverter unit is a three-phase PWM inverter, which inverts DC power into AC power with adjustable frequency and voltage. It accurately synthesizes a sinusoidal output voltage through PWM control strategy, thereby reducing voltage stress on the load. The output filter unit includes an LC filter, which is a passive filter network composed of filter inductors and filter capacitors connected in series or in parallel. The filter inductor is connected in series at the inverter output to impede high-frequency current surges, and the filter capacitor is connected in parallel at the output to absorb high-frequency voltage fluctuations. The two work together to form a low-pass filter characteristic, effectively filtering out high-frequency harmonic components generated by the inverter switching action. Through the combination of the above-mentioned rectification, inversion and LC filtering structures, not only is the energy conversion efficiency improved in the power conversion process, but the high-order harmonic interference at the output end is also significantly reduced, ensuring the purity and stability of the voltage waveform finally delivered to the load side, thereby optimizing the overall power quality.

[0050] As an optional embodiment, the bypass module includes a bypass switch and a series reactor branch, wherein: the bypass switch and the series reactor branch are connected in parallel; one end of the bypass module is connected to the output terminal of the hybrid transformer module, and the other end is connected to the load side.

[0051] Optionally, the bypass module consists of a bypass switch and a series reactor branch connected in parallel. The series reactor branch is used to limit the inrush current or fault current that may be generated when the bypass switch is closed, thus protecting the switching equipment. One end of the bypass module is connected to the output end of the hybrid transformer module, and the other end is connected to the load side, forming a redundant power supply path parallel to the hybrid transformer module. When the hybrid transformer module is shut down due to an internal fault or requires planned maintenance, the control system closes the bypass switch. At this time, the grid current no longer passes through the input transformer, rectifier unit, and inverter unit inside the hybrid transformer module, but flows directly to the load side through the closed bypass switch, thereby bypassing the main power link that is not in operation. This structure enables the load side to directly obtain power from the grid, avoiding power interruption caused by the shutdown of the main module, and realizing seamless or rapid power switching when the hybrid transformer module is out of operation, significantly improving the power supply continuity and reliability of the distribution network in equipment maintenance or fault scenarios.

[0052] Figure 3 This is a flowchart illustrating the operation control method for a power electronic transformer according to an embodiment of the present invention, as shown below. Figure 2 As shown, the method includes the following steps:

[0053] Step S302: Monitor the voltage and current on the grid side and the voltage and current on the load side in real time.

[0054] In this step, voltage and current sensors installed at the grid input end collect real-time voltage and line current signals from the grid side, respectively. The voltage sensor is used to obtain the effective value and frequency information of the grid voltage, while the current sensor is used to obtain the amplitude and rate of change of the load current flowing through the line compensation device. Simultaneously, voltage and current sensors installed at the load output end collect real-time voltage and load current signals from the load side, respectively, to monitor the working status of the load side in real time. Subsequently, the collected analog electrical signals are processed by the signal conditioning circuit and input to the digital interface of the control unit for analog-to-digital conversion. Based on the converted digital signals, the control unit uses a preset algorithm to calculate the specific values ​​of grid-side voltage, grid-side current, load-side voltage, and load-side current in real time, and uses this real-time data as the basis for judging the operating condition of the power electronic transformer and executing corresponding control strategies.

[0055] Step S304: When the voltage and current on the grid side and the voltage and current on the load side are both within their respective safe ranges, the operating mode of the power electronic transformer is determined to be the normal operating mode.

[0056] In this step, when determining the operating mode of the power electronic transformer, the control unit receives voltage and current monitoring data from the grid side and the load side in real time, and compares them one by one with the preset safety threshold range. If and only if the grid side voltage is within the allowable deviation range of the rated voltage, the grid side current does not exceed the rated carrying capacity of the line and equipment, the load side voltage is maintained at the qualified voltage level, and the load side current is within the normal load range, the control unit determines that the voltage and current of the grid side and the voltage and current of the load side are within their respective safety ranges, and thus determines that the power electronic transformer is currently in normal operating mode. In this mode, the series capacitor of the line compensation device is maintained to provide reactive power support, and the hybrid transformer module is controlled to perform routine voltage regulation.

[0057] Step S306: When the working mode is normal operation mode, the bypass mechanical switch in the power electronic transformer is opened, the thyristor protection unit is turned off, and the bypass switch is opened.

[0058] In this step, under normal operating conditions, the control unit sends control commands to the line compensation device and the bypass module to establish a normal power transmission path. Specifically, the control unit drives the bypass mechanical switch to remain open to cut off the path of line current bypassing the mechanical switch; at the same time, it controls the thyristor protection unit to remain off to ensure that the anti-parallel thyristor does not conduct, thereby allowing the series capacitor to be normally connected to the circuit to play a compensation role; in addition, the control unit controls the bypass switch in the bypass module to remain open to prevent the current from directly bypassing the hybrid transformer module, thereby ensuring that the power input from the grid side is processed sequentially through the line compensation device and the hybrid transformer module and finally delivered to the load side.

[0059] Step S308: The inductive impedance of the line is offset by the series capacitor in the power electronic transformer, and the voltage on the load side is maintained within the corresponding safe range by the DC / AC inverter unit in the power electronic transformer.

[0060] In this step, under normal operating mode, the power electronic transformer achieves voltage management through collaborative operation: on the one hand, the series capacitor in the line compensation device is connected to the grid-side line, and its capacitive impedance is used to offset the inherent inductive impedance of the distribution network line, thereby reducing voltage loss during line transmission and improving the voltage level at the end of the line; on the other hand, the DC / AC inverter unit in the power electronic transformer performs secondary regulation on the voltage after line compensation, and maintains the load-side voltage stable within the preset safety range by monitoring the load-side voltage in real time and adjusting the inverter output amplitude, ensuring that the load-side electrical equipment receives a high-quality and stable power supply.

[0061] Specifically, when the distribution network and load side are in normal operating condition, without abnormal impacts or equipment failures, the device enters normal operating mode. At this time, the voltage input from the grid side is first processed by the line compensation device. The bypass mechanical switch of the line compensation device is opened, the thyristor protection unit is turned off, and a series capacitor is connected to the line to offset the inductive voltage drop of the line and improve the line voltage level. The compensated voltage enters the hybrid module, which adjusts the voltage to the rated voltage value on the load side through a series of processes including input transformer isolation, AC / DC rectification, DC / AC inversion, and output filtering. Subsequently, the voltage is transmitted to the load side through the bypass module (at this time, the bypass switch is open) to provide stable and qualified power to the load and ensure the normal operation of the load.

[0062] As an optional embodiment, the peak current is determined based on the load-side current; if the peak current exceeds a preset current threshold, the operating mode of the power electronic transformer is determined to be the impact load mitigation mode; if the operating mode is the impact load mitigation mode, the predicted voltage drop is calculated based on the peak current; and the output voltage of the DC / AC inverter unit in the power electronic transformer is adjusted based on the predicted voltage drop.

[0063] Optionally, determining the peak current based on the load-side current refers to acquiring instantaneous current data from the load side in real time through a sampling circuit, and then filtering or averaging the data to extract the maximum current value characterizing the intensity of the impact load. This peak current serves as a core indicator for judging the degree of grid disturbance. When the peak current exceeds a preset current threshold, the operating mode is determined to be the impact load management mode. This means that the system, by setting a reasonable current warning line, automatically switches control from the conventional voltage maintenance logic to an active management logic for transient impacts when a sudden load increase causes the current to rise sharply and exceed the threshold, thus avoiding voltage drops due to response lag. In the impact load management mode, based on the peak... The current-based calculation predicts the voltage drop and adjusts the output voltage of the DC / AC inverter unit. Specifically, it uses Ohm's law or an equivalent impedance model to predict the voltage drop caused by the current flowing through the inductive impedance of the line based on the measured peak current and line impedance parameters. Then, it controls the DC / AC inverter unit to immediately output a compensation voltage higher than the current rated voltage on the load side to offset the voltage drop on the line. Through the above steps, it realizes the rapid identification of impact conditions and the active compensation of voltage fluctuations, effectively solving the problem that the traditional method of relying solely on series capacitors to offset inductive impedance cannot cope with the severe voltage fluctuations (voltage flicker) caused by instantaneous large currents, and significantly improving the stability of the load-side voltage and power quality.

[0064] Specifically, when there are impact loads such as high-power motors starting on the load side, the impact load will generate a short-term inrush current. When this current flows through the distribution network line, it will generate an additional inductive voltage drop, causing line voltage flicker and affecting the normal operation of the load. At this time, the device automatically switches to the impact load management mode. The series capacitor of the line compensation device responds quickly, using its own capacitive impedance to offset the inductive voltage drop generated by the inrush current, quickly suppressing voltage flicker and stabilizing the line voltage. At the same time, the hybrid module synchronously detects the voltage changes on the load side and adjusts the output voltage of the DC / AC inverter unit in real time to further compensate for voltage fluctuations, ensuring that the load side voltage remains stable and avoiding the impact of the impact load on electrical equipment and the distribution network.

[0065] As an optional embodiment, when an abnormality is detected in the line compensation device in the power electronic transformer, the operating mode of the power electronic transformer is determined to be fault / maintenance mode; when the operating mode is fault / maintenance mode, the thyristor protection unit in the power electronic transformer is controlled to turn on or the bypass mechanical switch is closed.

[0066] Optionally, when the control unit detects an abnormal operating condition in the line compensation device of the power electronic transformer, it determines the operating mode of the power electronic transformer to be fault / maintenance mode. In this operating mode, if the abnormality is manifested as overvoltage or fault current requiring rapid protection, the control unit controls the thyristor protection unit to conduct, short-circuiting the series capacitor to bypass it and protect the device. If the abnormality is manifested as the device requiring maintenance or long-term shutdown, the control unit controls the bypass mechanical switch to close, allowing the line current to flow directly through the bypass mechanical switch, achieving uncompensated operation of the line, thereby ensuring the continuity of power supply to the distribution network while troubleshooting or performing maintenance.

[0067] Specifically, when the line compensation device malfunctions or requires maintenance, it automatically switches to fault / maintenance mode to ensure power supply continuity. If the line compensation device malfunctions (e.g., due to an abnormal series capacitor), its internal thyristor protection unit quickly conducts, bypassing the series capacitor to prevent the fault from escalating. If the line compensation device requires maintenance, its internal bypass mechanical switch can be closed, enabling the line to operate without compensation. In this case, the load side can still obtain stable power supply through the hybrid transformer module or bypass module, ensuring uninterrupted power supply to the distribution network and improving power supply reliability.

[0068] As an optional embodiment, when an abnormality is detected in the hybrid module of the power electronic transformer, the operating mode of the power electronic transformer is determined to be fault / maintenance mode; when the operating mode is fault / maintenance mode, the PWM pulse of the DC / AC inverter unit in the power electronic transformer is blocked; and the bypass switch in the power electronic transformer is controlled to close.

[0069] Optionally, when the control unit detects an abnormality in the hybrid module of the power electronic transformer, it determines the operating mode of the power electronic transformer to be fault / maintenance mode. In this operating mode, the control unit immediately blocks the PWM pulse of the DC / AC inverter unit, causing the hybrid module to exit the operating state. At the same time, it controls the bypass switch in the bypass module to close, so that the voltage after line compensation on the grid side is directly transmitted to the load side through the bypass module, thereby ensuring the continuous power supply to the load side during the fault or maintenance of the hybrid module.

[0070] When the hybrid power module malfunctions or requires maintenance, the device automatically switches to fault / maintenance mode to ensure power supply continuity. If the hybrid power module malfunctions or requires maintenance, the hybrid power module immediately shuts down, and the bypass switch of the bypass module quickly closes, allowing line current to directly supply power to the load side via the bypass module.

[0071] It should be noted that, for the sake of simplicity, the foregoing method embodiments are all described as a series of actions. However, those skilled in the art should understand that the present invention is not limited to the described order of actions, because according to the present invention, some steps can be performed in other orders or simultaneously. Furthermore, those skilled in the art should also understand that the embodiments described in the specification are preferred embodiments, and the actions and modules involved are not necessarily essential to the present invention.

[0072] Through the above description of the embodiments, those skilled in the art can clearly understand that the operation control method of the power electronic transformer according to the above embodiments can be implemented by means of software plus necessary general-purpose hardware platform. Of course, it can also be implemented by hardware, but in many cases the former is a better implementation method. Based on this understanding, the technical solution of the present invention, in essence, or the part that contributes to the prior art, can be embodied in the form of a software product. This computer software product is stored in a storage medium (such as ROM / RAM, magnetic disk, optical disk) and includes several instructions to cause a terminal device (which may be a mobile phone, computer, server, or network device, etc.) to execute the methods described in the various embodiments of the present invention.

[0073] Embodiments of the present invention may provide a computer device. Optionally, in this embodiment, the computer device may be located in at least one of a plurality of network devices in a computer network. The computer device includes a memory and a processor.

[0074] The memory can be used to store software programs and modules, such as the program instructions / modules corresponding to the power electronic transformer operation control method and device in this embodiment of the invention. The processor executes various functional applications and data processing by running the software programs and modules stored in the memory, thereby realizing the aforementioned power electronic transformer operation control method. The memory may include high-speed random access memory, and may also include non-volatile memory, such as one or more magnetic storage devices, flash memory, or other non-volatile solid-state memory. In some instances, the memory may further include memory remotely located relative to the processor, and these remote memories can be connected to a computer terminal via a network. Examples of such networks include, but are not limited to, the Internet, corporate intranets, local area networks, mobile communication networks, and combinations thereof.

[0075] The processor can access the information and application programs stored in the memory via the transmission device to execute any of the above-mentioned power electronic transformer operation control methods.

[0076] According to an embodiment of the present invention, a power electronic transformer is provided, comprising: an input terminal of a line compensation device connected to the grid side, an output terminal of the line compensation device correspondingly connected to the input terminal of a hybrid transformer module, and an output terminal of the hybrid transformer module connected to the load side via a bypass module; the line compensation device includes a series capacitor, a thyristor protection unit, a bypass mechanical switch, and a series reactor, wherein the series capacitor, the thyristor protection unit, and the bypass mechanical switch are connected in parallel to form a parallel branch, and the parallel branch is connected in series with the series reactor; the hybrid transformer module includes an input transformer, an AC / DC rectifier unit, a DC / AC inverter unit, and an output filter unit, wherein the primary side of the input transformer is connected to the input terminal of the line compensation device. The output terminals are connected as follows: the secondary side of the input transformer is connected to the input terminal of the AC / DC rectifier unit; the DC side of the AC / DC rectifier unit is connected to the DC side of the DC / AC inverter unit; the output terminal of the DC / AC inverter unit is connected to the output filter unit; and the output filter unit is connected to the bypass module. This effectively suppresses voltage flicker during inductive load startup. The series capacitor can quickly respond to changes in line current, offsetting the voltage drop of the inrush current on the line impedance, and significantly reducing the voltage fluctuation amplitude in scenarios such as motor startup. This achieves the technical effect of reducing line voltage drop from the source and improving the efficiency of the treatment device, thereby solving the technical problem of insufficient suppression of line-side voltage drop by current end-of-line treatment devices.

[0077] Those skilled in the art will understand that all or part of the steps in the various methods of the above embodiments can be implemented by a program instructing the hardware related to the terminal device. The program can be stored in a non-volatile storage medium, which may include: flash drive, read-only memory (ROM), random access memory (RAM), disk or optical disk, etc.

[0078] Embodiments of the present invention also provide a non-volatile storage medium. Optionally, in this embodiment, the aforementioned non-volatile storage medium can be used to store the program code executed by the operation control method of the power electronic transformer provided in the above embodiments.

[0079] Optionally, in this embodiment, the non-volatile storage medium may be located in any computer terminal in a group of computer terminals in a computer network, or in any mobile terminal in a group of mobile terminals.

[0080] Optionally, in this embodiment, the non-volatile storage medium is configured to store program code for executing any of the above-described power electronic transformer operation control methods.

[0081] Embodiments of the present invention also provide a computer program product, including a computer program. Optionally, in this embodiment, when the computer program is executed by a processor, it can implement any of the above-described power electronic transformer operation control methods.

[0082] The sequence numbers of the above embodiments of the present invention are for descriptive purposes only and do not represent the superiority or inferiority of the embodiments.

[0083] In the above embodiments of the present invention, the descriptions of each embodiment have different focuses. For parts not described in detail in a certain embodiment, please refer to the relevant descriptions of other embodiments.

[0084] In the several embodiments provided in this application, it should be understood that the disclosed technical content can be implemented in other ways. The device embodiments described above are merely illustrative; for example, the division of units can be a logical functional division, and in actual implementation, there may be other division methods. For instance, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the displayed or discussed mutual coupling, direct coupling, or communication connection may be through some interfaces; the indirect coupling or communication connection between units or modules may be electrical or other forms.

[0085] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0086] Furthermore, the functional units in the various embodiments of the present invention can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. The integrated unit can be implemented in hardware or as a software functional unit.

[0087] If the integrated unit is implemented as a software functional unit and sold or used as an independent product, it can be stored in a non-volatile storage medium. Based on this understanding, the technical solution of the present invention, in essence, or the part that contributes to the prior art, or all or part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of the present invention. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, read-only memory (ROM), random access memory (RAM), portable hard drives, magnetic disks, or optical disks.

[0088] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A power electronic transformer, characterized in that, include: Line compensation device and hybrid transformer module, among which, The input terminal of the line compensation device is connected to the power grid side, the output terminal of the line compensation device is connected to the input terminal of the hybrid transformer module, and the output terminal of the hybrid transformer module is connected to the load side through a bypass module. The line compensation device includes a series capacitor, a thyristor protection unit, a bypass mechanical switch, and a series reactor. The series capacitor, the thyristor protection unit, and the bypass mechanical switch are connected in parallel to form a parallel branch, which is connected in series with the series reactor. The hybrid module includes an input transformer, an AC / DC rectifier unit, a DC / AC inverter unit, and an output filter unit. The primary side of the input transformer is connected to the output terminal of the line compensation device, the secondary side of the input transformer is connected to the input terminal of the AC / DC rectifier unit, the DC side of the AC / DC rectifier unit is connected to the DC side of the DC / AC inverter unit, the output terminal of the DC / AC inverter unit is connected to the output filter unit, and the output filter unit is connected to the bypass module.

2. The power electronic transformer according to claim 1, characterized in that, The thyristor protection unit adopts an anti-parallel thyristor structure.

3. The power electronic transformer according to claim 1, characterized in that, in: The AC / DC rectifier unit is a three-phase PWM rectifier; The DC / AC inverter unit is a three-phase PWM inverter; The output filtering unit includes an LC filter, wherein the LC filter includes a filter inductor and a filter capacitor.

4. The power electronic transformer according to claim 1, characterized in that, The bypass module includes a bypass switch and a series reactor branch, wherein: The bypass switch is connected in parallel with the series reactor branch; One end of the bypass module is connected to the output end of the hybrid converter module, and the other end is connected to the load side.

5. A method for operating and controlling a power electronic transformer, characterized in that, For controlling the power electronic transformer according to any one of claims 1 to 4, comprising: Real-time monitoring of voltage and current on the grid side and on the load side; When the voltage and current on the grid side and the voltage and current on the load side are both within their respective safe ranges, the operating mode of the power electronic transformer is determined to be the normal operating mode. When the operating mode is the normal operating mode, the bypass mechanical switch in the power electronic transformer is opened, the thyristor protection unit is turned off, and the bypass switch is opened. The inductive impedance of the line is offset by the series capacitor in the power electronic transformer, and the voltage on the load side is maintained within the corresponding safe range by the DC / AC inverter unit in the power electronic transformer.

6. The method according to claim 5, characterized in that, Also includes: Determine the peak current based on the current on the load side; If the peak current exceeds a preset current threshold, the operating mode of the power electronic transformer is determined to be the impact load mitigation mode. When the operating mode is the impact load mitigation mode, the predicted voltage drop is calculated based on the peak current; Based on the predicted voltage drop, the output voltage of the DC / AC inverter unit in the power electronic transformer is adjusted.

7. The method according to claim 5, characterized in that, Also includes: If an abnormality is detected in the line compensation device of the power electronic transformer, the operating mode of the power electronic transformer is determined to be fault / maintenance mode. When the operating mode is the fault / maintenance mode, the thyristor protection unit in the power electronic transformer is turned on or the bypass mechanical switch is closed.

8. The method according to claim 5, characterized in that, Also includes: If an abnormality is detected in the hybrid module of the power electronic transformer, the operating mode of the power electronic transformer is determined to be fault / maintenance mode. When the operating mode is the fault / maintenance mode, the PWM pulses of the DC / AC inverter unit in the power electronic transformer are blocked; Control the closing of the bypass switch in the power electronic transformer.

9. A non-volatile storage medium, characterized in that, The non-volatile storage medium includes a stored program, wherein, when the program is executed, it controls the device containing the non-volatile storage medium to perform the operation control method of the power electronic transformer according to any one of claims 5 to 8.

10. A computer device, characterized in that, include: Memory and processor The memory stores computer programs; The processor is configured to execute a computer program stored in the memory, wherein when the computer program is executed, the processor performs the operation control method of the power electronic transformer according to any one of claims 5 to 8.

11. A computer program product, comprising a computer program, characterized in that, When the computer program is executed by the processor, it implements the operation control method of the power electronic transformer according to any one of claims 5 to 8.

Images