High-current generator with adjustable phase

Abstract

The invention discloses a phase-adjustable large-current generator, and the generator comprises a main circuit module, and a topological structure of the main circuit module employs a multi-stage IGBT inverter; the phase control module inputs a power grid voltage signal through a voltage transformer, adopts an SOGI-PLL structure to improve signal tracking precision, and combines a virtual synchronous machine technology to enhance system balance and a self-adaptive control strategy to dynamically adjust an output signal so as to realize phase control and synchronization; the electromagnetic compatibility optimization module adopts a layered shielding design and is combined with an optical fiber to transmit a control signal, so that the electromagnetic compatibility of equipment is improved; a relay protection test integration module, wherein the relay protection test integration module comprises a differential protection test mode and a distance protection test mode; according to the invention, the problems of low phase adjustment precision, poor synchronization stability and insufficient electromagnetic compatibility of a large current generator in a new energy grid-connected environment are solved.

Description

Technical Field

[0001] The present invention relates to the technical field of measuring electric variables, in particular to the technical field of equipment for providing reference values in measuring instruments, specifically to a large current generator with adjustable phase. Background Art

[0002] Currently, the increasing demand for renewable energy has led to the large-scale integration of new energy devices such as wind power and solar photovoltaic power generation. This has led to changes in the structure and operating characteristics of the power grid, including increased stability, power quality, and the complexity of protection and control strategies. A high-current generator is a device used to generate high currents, typically operating on the principle of stepping down the voltage and increasing the current. It converts the input low-voltage, high-current into the required high-current output through a transformer. It is primarily used for testing, calibration, and experimentation of electrical equipment. However, the changes in grid characteristics brought about by the integration of new energy sources require corresponding optimization of its design to adapt to new demands.

[0003] After new energy equipment is connected to the power grid, due to the randomness and intermittent nature of the new energy equipment, this may cause power fluctuations in the power grid and affect the stability of the power grid; at the same time, new energy equipment is connected to the grid through power electronic converters, which may introduce harmonics and affect the quality of electric energy; in response to this situation, a large current generator is required to enhance synchronization stability in the face of power grid fluctuations, simulate the grid characteristics after the new energy equipment is connected to the power grid, and enable the large current generator to automatically adjust the output parameters according to the power grid status and the operation of the new energy equipment, realize optimized control, and test and optimize the power equipment.

[0004] Therefore, it is necessary to improve the high current generator in the prior art to solve the above problems. Summary of the Invention

[0005] The present invention overcomes the shortcomings of the existing technology and provides a phase-adjustable large current generator, aiming to solve the problems in the existing technology of low phase adjustment accuracy, poor synchronization stability and insufficient electromagnetic compatibility of traditional large current generators caused by changes in grid characteristics after new energy is connected to the grid.

[0006] To achieve the above object, the present invention adopts the following technical solution: a phase-adjustable high current generator, comprising:

[0007] A main circuit module, wherein the topology of the main circuit module adopts a multi-level IGBT inverter, including: a modular multi-level inverter or a parallel IGBT bridge structure;

[0008] A phase control module, wherein the phase control module inputs a grid voltage signal through a voltage transformer; the phase control module comprises: an input unit, a control unit, and an output unit;

[0009] The input unit uses a SOGI-PLL structure combining a second-order generalized integrator and a digital phase-locked loop to process the grid voltage signal. The control unit uses virtual synchronous machine technology to adjust the frequency and phase of the output signal based on the grid voltage phase information provided by the SOGI-PLL structure. It then uses an adaptive control strategy to monitor changes in system parameters in real time and adjust the virtual inertia parameters according to changes in load impedance. The output unit generates a control signal based on the adjusted parameters to control the main circuit module.

[0010] An electromagnetic compatibility optimization module, wherein the electromagnetic compatibility optimization module adopts optical fiber transmission and layered shielding, including a magnetic shielding layer and a conductive shielding layer;

[0011] A relay protection test integrated module includes a differential protection test mode and a distance protection test mode.

[0012] In a preferred embodiment of the present invention, the multi-level IGBT inverter increases the output current capacity by connecting multiple IGBT modules in parallel, and adopts IGBT modules with a withstand voltage of ≥1700V and a current of ≥500A.

[0013] In a preferred embodiment of the present invention, the IGBT module is equipped with a water cooling system, the flow rate of the water cooling system is ≥10L / min, the thermal resistance is <0.02℃ / W, the junction temperature is <120℃, and the output copper busbar has a built-in hollow water channel.

[0014] In a preferred embodiment of the present invention, the phase control module further includes a temperature compensation unit, which monitors the operating temperature of the IGBT module in real time and compensates the phase control signal according to temperature changes.

[0015] In a preferred embodiment of the present invention, the magnetic shielding layer adopts a 2 mm thick Mu-metal shell to suppress the interference of low-frequency magnetic fields, and the attenuation is ≥35 dB.

[0016] In a preferred embodiment of the present invention, the conductive shielding layer uses a conductive shielding layer with a copper mesh coverage of ≥95%, combined with a conductive coating to suppress high-frequency radiation with an attenuation of ≥45dB.

[0017] In a preferred embodiment of the present invention, when the relay protection test integrated module detects a load abnormality, it blocks the IGBT pulse within 5 μs and quickly cuts off the output.

[0018] In a preferred embodiment of the present invention, the phase control module uses a combination of a closed-loop Hall sensor and a Rogowski coil for current feedback, the closed-loop Hall sensor is used to measure low-frequency and DC current, the Rogowski coil is used to measure high-frequency current, and the sensor error is dynamically corrected through a data fusion algorithm.

[0019] In a preferred embodiment of the present invention, the relay protection test integrated module can automatically generate two large currents with a phase difference adjustable from 0° to 360° under differential protection testing to simulate in-zone / out-of-zone faults; under distance protection testing, the voltage-current phase angle can be continuously adjusted from 0° to 90° to simulate the impedance changes after new energy equipment is connected to the power grid.

[0020] In a preferred embodiment of the present invention, the busbar of the main circuit module adopts a laminated copper busbar design, the distance between the conductive layers is less than 100 μm, and the insulating material is one of polypropylene, cross-linked polyethylene and polyimide film to reduce electromagnetic noise and interference.

[0021] The present invention solves the defects existing in the background technology and has the following beneficial effects:

[0022] (1) The present invention provides a large current generator with adjustable phase. The main circuit module adopts a multi-level IGBT inverter topology to achieve high current output and flexible phase adjustment; the phase control module combines the SOGI-PLL structure and virtual synchronous machine technology to improve phase tracking accuracy and system stability; the electromagnetic compatibility optimization module reduces electromagnetic interference through layered shielding design and optical fiber isolation communication; the relay protection test integration module supports multiple protection test modes to ensure the comprehensiveness and practicality of the equipment.

[0023] (2) The present invention combines the SOGI-PLL structure of the phase control module with the virtual synchronous machine technology. The phase control module significantly improves the tracking accuracy of the grid voltage signal through the SOGI-PLL structure, effectively filters out high-frequency noise and harmonics, extracts the fundamental component, and ensures the accuracy of phase tracking. The virtual synchronous machine technology starts from the system stability and simulates the inertia and damping characteristics of the synchronous generator to enhance the internal stability of the large current generator when connected to a large number of new energy equipment, effectively avoiding the synchronization instability problem that may occur in traditional digital phase-locked loop technology. Although VSG technology may have a certain impact on the response speed while enhancing stability, the high tracking speed of the SOGI-PLL structure just makes up for this shortcoming. The two complement each other and jointly optimize the system performance. Compared with the existing technology, it further achieves the effect of maintaining high-precision phase control and stable output in a complex grid environment.

[0024] (3) The present invention adopts a layered shielding design through the electromagnetic compatibility optimization module, including a magnetic shielding layer and a conductive shielding layer, combined with optical fiber transmission control signals, to effectively suppress electromagnetic interference. The magnetic shielding layer suppresses low-frequency magnetic field interference, and the conductive shielding layer suppresses high-frequency radiation interference. The layered shielding design shields electromagnetic interference from different frequency bands, and optical fiber transmission blocks ground loop interference, thereby improving the electromagnetic compatibility of the equipment. In addition, the busbar of the main circuit module adopts a laminated copper busbar design. Through the layered shielding design, optical fiber isolation communication and the laminated copper busbar design of the main circuit module, a set of multi-level electromagnetic compatibility strategies from the inside to the outside is formed. Compared with the existing technology, it further achieves the effect of stable operation in complex electromagnetic environments and significantly reducing electromagnetic interference.

[0025] (4) The present invention organically combines the SOGI-PLL structure, virtual synchronous machine technology, adaptive control strategy and real-time temperature correction compensation through the phase control module. The SOGI-PLL structure starts from tracking the signal to ensure the accuracy of phase tracking. The virtual synchronous machine technology improves the system stability and enhances the system inertia and damping. The adaptive control strategy ensures dynamic adjustment of the output and achieves a balance between dynamic performance and stability. The three start from tracking the signal, improving the system stability and ensuring dynamic adjustment of the output, realizing high-precision phase control and synchronization, forming a complete content control system of the large current generator, and significantly improving the performance and reliability of the large current generator in the new energy grid-connected environment.

[0026] (5) The present invention uses a combination of a closed-loop Hall effect sensor and a Rogowski coil through current feedback, and performs signal processing through a data fusion algorithm. The closed-loop Hall effect sensor is used for measuring low-frequency and DC current, and the Rogowski coil is used for measuring high-frequency current. The combination of the two can ensure high-precision measurement in different current ranges and complex electromagnetic environments. Compared with the existing technology, the measurement accuracy and anti-interference ability of the equipment are further improved. In particular, after the new energy equipment is connected to the power grid, it can effectively deal with current fluctuations and electromagnetic interference, ensuring the stable operation of the equipment. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments described in the present invention. Those skilled in the art can also derive other drawings based on these drawings without inventive efforts.

[0028] Figure 1 It is a structural diagram of a preferred embodiment of the present invention. DETAILED DESCRIPTION

[0029] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0030] In the following description, many specific details are set forth to facilitate a full understanding of the present invention. However, the present invention may also be implemented in other ways different from those described herein. Therefore, the scope of protection of the present invention is not limited to the specific embodiments disclosed below.

[0031] Application Overview:

[0032] Traditional high-current generators mostly use industrial frequency transformer current boosting or LC resonant boosting technology, which have technical bottlenecks such as low phase adjustment accuracy and slow dynamic response. Especially in the grid scenario with high penetration of new energy equipment, existing equipment has difficulty tracking the dynamic changes of grid impedance in real time, resulting in inaccurate fault current phase simulation. When expanding in parallel, they adopt a simple master-slave control strategy, which has problems such as large current sharing deviation and low synchronization accuracy, and cannot meet the phase consistency requirements of double-sided injection of differential protection. In addition, traditional equipment generally adopts a direct parallel structure of copper busbars, resulting in insufficient electromagnetic interference suppression capability and conducted emission >30dBμV, affecting the reliability of high-precision measurement systems.

[0033] This application combines the SOGI-PLL structure, virtual synchronous machine technology, and adaptive control strategy to sense the changes in the equivalent impedance of the power grid in real time and dynamically adjust the output characteristics, achieving phase adjustment and improving the power grid adaptability of the equipment; through the magnetic-electric layered shielding structure, it solves the problem of high-frequency radiation interference during large current output and significantly improves the electromagnetic compatibility of the equipment.

[0034] Example device structure:

[0035] like Figure 1 As shown, through the organic combination of the main circuit module, phase control module, electromagnetic compatibility optimization module and relay protection test integration module, a phase-adjustable high current generator is provided, which solves the impact of changes in grid characteristics caused by the connection of new energy equipment to the grid on the performance of traditional high current generators.

[0036] The main circuit module is used to realize the transmission, distribution and control of electric energy. After the new energy equipment is connected to the power grid, the operating characteristics of the power grid change. The high current generator is required to output high current and flexibly adjust the phase to simulate the characteristics of the power grid after the new energy equipment is connected.

[0037] The topology of the main circuit module adopts a multi-level IGBT inverter, specifically a modular multi-level inverter or a parallel IGBT bridge structure. This topology can achieve high current output and flexible phase adjustment; it can output current ≤10kA; it can meet the needs of new energy equipment for large current and phase adjustment after being connected to the power grid, ensuring the stable operation of the equipment in complex power grid environments.

[0038] New energy equipment is connected to the grid through power electronic converters, which will introduce harmonics and affect the power quality. The modular multi-level inverter uses multiple IGBT modules to achieve high voltage and high current output. Each module can be independently controlled to generate multiple levels of output voltage, which can be closer to a sine waveform, thereby reducing harmonic content and improving power quality. The parallel IGBT bridge structure increases the output current capacity by connecting multiple IGBT modules in parallel, and at the same time achieves flexible control through phase adjustment. Preferably, an IGBT module with a withstand voltage ≥1700V and a current ≥500A is used, such as the Infineon FF450R17ME4. The IGBT module is equipped with a water cooling system with a flow rate ≥10L / min, a thermal resistance <0.02℃ / W, a junction temperature <120℃, and a built-in hollow water channel in the output copper busbar.

[0039] In order to further improve the quality of the output waveform, high-frequency PWM modulation technology is adopted, and the switching frequency

[0040] ≥50kHz, combined with an LC filter with a cutoff frequency of 1.5kHz, it can effectively filter out high-frequency harmonics and control the total harmonic distortion rate below 0.5%. High-frequency PWM modulation not only improves the quality of the output waveform and reduces harmonic distortion, but also further improves the quality of electric energy; the LC filter plays a role in filtering out high-frequency harmonics, ensuring the waveform quality of the output current;

[0041] This design also uses multi-winding coupled output, superimposing currents through magnetic coupling, thereby significantly increasing output capacity. Magnetic coupling is used to superimpose the output currents of multiple parallel modules to achieve high current output.

[0042] The busbar of the main circuit module adopts a laminated copper busbar design to reduce the high voltage spikes generated by the IGBT during switching transients. The laminated copper busbar is designed with several conductive layers stacked together, and insulating material is added between each layer to reduce the inductance of the busbar. The low inductance design reduces the generation of electromagnetic noise and reduces the impact of electromagnetic interference on the system. Specifically, the distance between the conductive layers is less than 100μm; the insulating material is one of polypropylene, cross-linked polyethylene and polyimide film.

[0043] The phase control module is used to achieve high-precision phase control and synchronization. After the new energy equipment is connected to the power grid, in the face of changes in grid characteristics, it enhances synchronization stability, simulates the grid characteristics after the new energy equipment is connected to the power grid, and enables the high current generator to automatically adjust the output parameters according to the grid status and the operation of the new energy equipment, to achieve optimized control and test and optimize the power equipment.

[0044] The phase control module inputs the grid voltage signal through a voltage transformer and uses the digital phase-locked loop (PLL) technology commonly used in the prior art to achieve phase tracking. This application uses a second-order generalized integrator (SOGI) to achieve phase tracking, forming a SOGI-PLL structure. The second-order generalized integrator constructs a filter structure that receives a sinusoidal input signal and outputs two mutually orthogonal signals. These two signals can be used to accurately extract the amplitude, frequency, and phase information of the input signal.

[0045] SOGI is used to filter and integrate the grid voltage signal, effectively filtering out high-frequency noise and harmonics and extracting the fundamental component of the grid voltage. This further addresses the harmonic issues that are prone to occur in the grid after new energy equipment is connected to the grid. By filtering out harmonics, the SOGI-PLL structure can more accurately track the phase of the grid voltage, improving phase tracking accuracy.

[0046] However, with the integration of a large number of renewable energy sources into the power grid, due to the temporal characteristics of renewable energy devices, multi-timescale interactions and multi-machine interactions between devices can easily lead to grid-connected system stability issues, which can easily cause synchronization instability in digital phase-locked loop technology. To address the above issues, this application combines virtual synchronous machine technology and adaptive control strategies on the basis of the above to improve the synchronization efficiency of large current generators and maintain the system balance point.

[0047] The synchronization instability problems of renewable energy grid-connected systems can be summarized into the following three categories:

[0048] 1. Under certain operating conditions, the system may not have a stable equilibrium point, resulting in synchronization instability;

[0049] 2. Even if the system has an equilibrium point, it may not be able to remain stable when subjected to small disturbances, resulting in synchronous instability;

[0050] 3. When system parameters or operating conditions change, the system may not be able to smoothly transition to the new equilibrium point, resulting in synchronization instability.

[0051] Therefore, maintaining this balance point is crucial. Virtual synchronous machine technology is a control strategy that can simulate the dynamic characteristics of synchronous generators and enhance the inertia and damping of the system. This allows the system to maintain its balance point even when a large number of energy devices are connected and the load increases, thereby improving the system's stability and anti-interference ability. By simulating the rotation equation of the synchronous generator, VSG technology enables new energy devices to provide inertia and damping support similar to that of traditional synchronous generators, thereby enhancing the stability of the system and avoiding the synchronization instability of digital phase-locked loop technology. The inertia model formula of VSG is: Among them, J is the virtual inertia, P m is the mechanical power, P e is the electric power, ω is the rotor angular velocity, ω s is the synchronous angular velocity, δ is the power angle;

[0052] The calculation formula of the virtual impedance voltage drop of VSG is: V out =V ref -Z v I, where V out is the output voltage, V ref is the reference voltage, Z v is the virtual impedance, I is the output current;

[0053] The phase control module significantly improves the tracking accuracy of the grid voltage signal through the SOGI-PLL structure, effectively filtering out high-frequency noise and harmonics, extracting the fundamental component, and ensuring phase tracking accuracy. Virtual Synchronous Generator (VSG) technology focuses on system stability. By simulating the inertia and damping characteristics of synchronous generators, it enhances the internal stability of high-current generators when connected to a large number of new energy devices, effectively avoiding the synchronization instability issues that can occur with traditional digital phase-locked loop technology. Although VSG technology may have a certain impact on response speed while enhancing stability, the high tracking speed of the SOGI-PLL structure offsets this shortcoming. The two complement each other and jointly optimize system performance.

[0054] For output current control, the phase control module adopts an adaptive control strategy to monitor the changes in system parameters in real time. According to the changes in load impedance, when the system load fluctuates greatly, the adaptive inertia control adjusts the virtual inertia parameter J in real time to achieve a balance between dynamic performance and stability. The formula for adaptive inertia control is: J ad =J0+k p (P ref -P e ), where J ad is the adaptive inertia, J0 is the initial inertia, k p is the proportional coefficient, P refAs the reference power, the high current generator can maintain stable output performance when facing complex power grid environment and fluctuations of new energy equipment.

[0055] The above-mentioned current feedback uses a combination of closed-loop Hall sensors and Rogowski coils. The closed-loop Hall sensors are used to measure low-frequency and DC currents, while the Rogowski coils are used to measure high-frequency currents. The signals of these two sensors are integrated through signal processing. The closed-loop Hall sensors have the characteristics of high precision, fast response, and low thermal drift, while the Rogowski coils have the advantages of non-contact measurement, wide measurement range, and strong anti-interference capabilities. The combination of the two ensures high-precision measurement in different current ranges and complex electromagnetic environments.

[0056] Adopting data fusion algorithms, such as Kalman filtering, to fuse the signals of closed-loop Hall sensors and Rogowski coils, it is possible to dynamically correct sensor errors and achieve high-precision positioning and measurement. in, Represents the estimation of the state vector at time k, k-1, that is, the final state estimation and the prediction of the current state; K k is the Kalman gain, z k is the confidence level in the difference between the measured and predicted values at time k, is the prediction of the measured value at time k.

[0057] Since adaptive control will adjust the on-state voltage of the IGBT module, the phase offset caused by the voltage change of the IGBT module is compensated by temperature in real time, which further improves the stability of the phase control and the test accuracy. Specifically, by setting a temperature sensor such as PT100, the stability of the phase control is improved. The temperature real-time compensation formula is: c =δ m -k t (T-T0), where δ c is the phase after compensation, δ m is the measured phase, k t is the temperature compensation coefficient, T, T0 are the current temperature and reference temperature.

[0058] The phase control module is an organic combination of SOGI-PLL structure, virtual synchronizer technology, adaptive control strategy and real-time temperature correction compensation. The SOGI-PLL structure starts with tracking signals to ensure the accuracy of phase tracking. The virtual synchronizer technology improves system stability and enhances system inertia and damping. The adaptive control strategy ensures dynamic output adjustment to achieve a balance between dynamic performance and stability. The three start from tracking signals, improving system stability and ensuring dynamic output adjustment to achieve high-precision phase control and synchronization, forming a complete content control system for large current generators, which significantly improves the performance and reliability of large current generators in new energy grid-connected environments.

[0059] The electromagnetic compatibility optimization module is used to improve the equipment's anti-interference capability and electromagnetic compatibility, ensuring that the equipment can still operate stably in complex electromagnetic environments. New energy equipment such as wind power generation and solar photovoltaic power generation equipment are connected to the grid through power electronic converters, which will generate high-frequency electromagnetic interference and affect the power quality. By suppressing electromagnetic interference, the stable operation of the equipment can be ensured.

[0060] Specifically, the magnetic shielding layer of the high current generator is set on the inner layer of the device, close to the internal circuit of the device, and uses a 2mm thick high magnetic permeability material such as Mu-metal material to make the shell, which can suppress the interference of low-frequency magnetic fields of 50Hz to 1kHz, with an attenuation of 35dB or more; the conductive shielding layer is set on the outer layer of the magnetic shielding layer, directly in contact with the external environment, using a conductive shielding layer with a copper mesh coverage rate of 95% or more, combined with a conductive coating, which can effectively suppress high-frequency radiation above 1MHz, with an attenuation of 45dB or more;

[0061] The main function of the magnetic shielding layer is to shield low-frequency magnetic fields. Low-frequency magnetic fields have strong penetrating power, so they need to be close to the internal circuits of the device to reduce the impact of low-frequency magnetic fields on the device. The main function of the conductive shielding layer is to shield high-frequency electromagnetic waves. High-frequency electromagnetic waves have weak penetrating power, so setting it on the outer layer can effectively block external high-frequency interference and protect the internal circuits.

[0062] In addition, during signal transmission, the control signal is transmitted through optical fiber, such as the Avago AFBR-1521Z optical fiber communication. Optical fiber transmission has high anti-interference ability and can effectively block ground loop interference, ensuring stable transmission of control signals in complex electromagnetic environments.

[0063] The electromagnetic compatibility optimization module utilizes a layered shielding design and fiber-optic isolated communication to improve the device's anti-interference capabilities and electromagnetic compatibility. Furthermore, the main circuit module's busbars utilize a laminated copper busbar design. This layered shielding design, fiber-optic isolated communication, and the laminated copper busbar design of the main circuit module form a multi-layered electromagnetic compatibility strategy from the inside out. These strategies work together to significantly improve the device's anti-interference capabilities and electromagnetic compatibility.

[0064] The relay protection test integration module is used to support multiple protection test modes to ensure the comprehensiveness and practicality of the equipment. After the new energy is connected, the module can simulate the complex working conditions of the new energy equipment after being connected to the grid and conduct a comprehensive test of the relay protection device:

[0065] Specifically, under differential protection testing, two large currents are automatically generated with a phase difference adjustable from 0° to 360° to simulate internal / external faults. After renewable energy access, the fault characteristics of renewable energy equipment connected to the grid can be simulated. Under distance protection testing, the voltage-current phase angle can be continuously adjusted from 0° to 90°, simulating the impedance changes of renewable energy equipment connected to the grid.

[0066] After the new energy is connected, when a load abnormality is detected, the IGBT pulse is blocked within 5μs, and the output is quickly cut off in the event of overcurrent to protect the safety of equipment and personnel. At the same time, it can record the current, voltage, and phase data 1 second before and after the fault with a sampling rate of 100kHz, providing detailed data support for fault analysis.

[0067] The present invention provides a phase-adjustable high-current generator through the organic combination of a main circuit module, a phase control module, an electromagnetic compatibility optimization module, and a relay protection test integration module, thereby solving the impact of changes in grid characteristics caused by the connection of new energy equipment to the grid on the performance of traditional high-current generators. Compared with the existing technology, the present invention has achieved significant improvements and enhancements in high current output, flexible phase adjustment, harmonic reduction, improved power quality, phase control accuracy, system stability, electromagnetic compatibility, test capability, and measurement accuracy, significantly improving the performance and reliability of the equipment in a new energy grid-connected environment.

[0068] For the above equipment, experiments were conducted to prove the high synchronization and anti-electromagnetic interference performance of the present invention:

[0069] Experimental Example 1:

[0070] Under the conditions of different proportions of new energy equipment access, the synchronization performance of the present invention and the traditional high current generator was tested. The traditional high current generator uses power frequency transformer current boosting or LC resonance boosting technology;

[0071] The high-current generator of the present invention and a traditional high-current generator were respectively connected to a power grid simulator; a new energy device simulator was used to simulate different proportions of new energy devices connected to the power grid (20%, 40%, and 60%); the power grid simulator was set to generate the same power grid voltage signal, including fundamental and harmonic components; and an oscilloscope and a power analyzer were used to record the output current and phase of the device.

[0072] Table 1 The impact of the proportion of connected new energy equipment on synchronization

[0073]

[0074] When different proportions of new energy devices are connected to the large current generator of the present invention, the phase tracking accuracy is higher and the phase difference between the output current and the grid voltage is smaller.

[0075] The present invention adopts SOGI-PLL structure and virtual synchronous machine (VSG) technology. SOGI-PLL structure can effectively filter out high-frequency noise and harmonics, extract fundamental components, and ensure the accuracy of phase tracking. VSG technology enhances the stability of the system by simulating the inertia and damping characteristics of the synchronous generator. Even when the proportion of new energy equipment access increases, the balance point of the system can be maintained to avoid synchronous instability; the phase control module of the present invention is combined with an adaptive control strategy, which can monitor the changes in system parameters in real time, adjust the virtual inertia parameters according to the changes in load impedance, and achieve a balance between dynamic performance and stability. Therefore, when different proportions of new energy equipment are connected, the large current generator of the present invention can still maintain high-precision phase control.

[0076] Experimental Example 2:

[0077] Under the conditions of different proportions of new energy equipment access, the anti-electromagnetic interference capabilities of the present invention and traditional high-current generators were tested; traditional high-current generators use power frequency transformer current boosting or LC resonant boosting technology;

[0078] The high current generator of the present invention and a traditional high current generator were connected to a power grid simulator respectively; a new energy device simulator was used to simulate different proportions of new energy devices connected to the power grid (20%, 40%, 60%); electromagnetic interference sources were arranged around the equipment to generate high-frequency electromagnetic interference signals, such as high-frequency signals above 1 MHz; and an oscilloscope and a power analyzer were used to record the output current and phase of the equipment.

[0079] Table 2 Impact of the proportion of connected new energy equipment on the ability to resist electromagnetic interference

[0080]

[0081]

[0082] When new energy devices of different proportions are connected to the high current generator of the present invention, the output current and phase fluctuations are small and the anti-interference ability is stronger.

[0083] This invention utilizes a layered shielding design, including magnetic and conductive shielding layers, to effectively suppress interference from low-frequency magnetic fields. Furthermore, control signals are transmitted via optical fiber, effectively blocking ground loop interference and ensuring stable transmission of control signals in complex electromagnetic environments. The main circuit module's busbars utilize laminated copper busbars to reduce the high voltage spikes generated by IGBT switching transients, lower the busbar inductance, and minimize electromagnetic noise. These design optimizations significantly enhance the device's anti-interference capabilities.

[0084] The above description is based on the ideal embodiment of the present invention. Based on the above description, relevant personnel can make various changes and modifications without departing from the technical scope of this invention. The technical scope of this invention is not limited to the content of the specification and must be determined according to the scope of the claims.

Claims

1. A phase-adjustable large current generator, characterized in that: Included modules: A main circuit module, wherein the topology of the main circuit module adopts a multi-level IGBT inverter, including: a modular multi-level inverter or a parallel IGBT bridge structure; A phase control module, wherein the phase control module inputs a grid voltage signal through a voltage transformer; the phase control module comprises: an input unit, a control unit, and an output unit; The input unit uses a SOGI-PLL structure combining a second-order generalized integrator and a digital phase-locked loop to process the grid voltage signal. The control unit uses virtual synchronous machine technology to adjust the frequency and phase of the output signal based on the grid voltage phase information provided by the SOGI-PLL structure. It then uses an adaptive control strategy to monitor changes in system parameters in real time and adjust the virtual inertia parameters according to changes in load impedance. The output unit generates a control signal based on the adjusted parameters to control the main circuit module. An electromagnetic compatibility optimization module, wherein the electromagnetic compatibility optimization module adopts optical fiber transmission and layered shielding, including a magnetic shielding layer and a conductive shielding layer; A relay protection test integrated module includes a differential protection test mode and a distance protection test mode.

2. The phase-adjustable high current generator according to claim 1, characterized in that: The multi-level IGBT inverter increases the output current capacity by connecting multiple IGBT modules in parallel, and adopts IGBT modules with a withstand voltage of ≥1700V and a current of ≥500A.

3. The phase-adjustable high current generator according to claim 2, characterized in that: The IGBT module is equipped with a water cooling system with a flow rate of ≥10L / min, a thermal resistance of <0.02°C / W, a junction temperature of <120°C, and a built-in hollow water channel in the output copper busbar.

4. The phase-adjustable high current generator according to claim 1, characterized in that: The phase control module further includes a temperature compensation unit, which monitors the operating temperature of the IGBT module in real time and compensates the phase control signal according to temperature changes.

5. The phase-adjustable high current generator according to claim 1, characterized in that: The magnetic shielding layer adopts a 2mm thick Mu-metal shell to suppress the interference of low-frequency magnetic fields, with an attenuation of ≥35dB.

6. The phase-adjustable high current generator according to claim 1, characterized in that: The conductive shielding layer uses a conductive shielding layer with a copper mesh coverage rate of ≥95%, combined with a conductive coating to suppress high-frequency radiation, with an attenuation of ≥45dB.

7. The phase-adjustable high current generator according to claim 1, characterized in that: When the relay protection test integrated module detects a load abnormality, it blocks the IGBT pulse within 5 μs and quickly cuts off the output.

8. The phase-adjustable high current generator according to claim 1, characterized in that: The phase control module uses a combination of a closed-loop Hall sensor and a Rogowski coil for current feedback. The closed-loop Hall sensor is used to measure low-frequency and DC currents, and the Rogowski coil is used to measure high-frequency currents. Sensor errors are dynamically corrected through a data fusion algorithm.

9. The phase-adjustable high current generator according to claim 1, characterized in that: The relay protection test integrated module can automatically generate two large currents with a phase difference adjustable from 0° to 360° under differential protection testing to simulate in-zone / out-of-zone faults; under distance protection testing, the voltage-current phase angle can be continuously adjusted from 0° to 90° to simulate the impedance changes after new energy equipment is connected to the power grid.

10. The phase-adjustable high current generator according to claim 1, characterized in that: The busbar of the main circuit module adopts a laminated copper busbar design, the distance between the conductive layers is less than 100 μm, and the insulating material is one of polypropylene, cross-linked polyethylene and polyimide film to reduce electromagnetic noise and interference.

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