Method, system, device and equipment for controlling transformer magnetizing inrush current and medium

Abstract

This application provides a method, system, device, equipment, and medium for controlling transformer inrush current, specifically a phase-controlled closing module applied to the method for controlling transformer inrush current, relating to the field of power technology. The method includes: acquiring the opening angle of the circuit breaker at the time of its last opening; then, based on this opening angle and the internal environmental parameters of the circuit breaker, determining the target closing angle of the circuit breaker; and finally, controlling the circuit breaker to close based on the target closing angle to suppress the transformer's inrush current. Through this method, the transient magnetic flux generated during closing can be completely canceled out by the residual steady-state magnetism from opening, effectively suppressing the inrush current amplitude. Throughout the process, the excitation current will be maintained at a low level close to steady state, ensuring the safe and stable operation of the transformer and the power grid, and improving the operational safety and power supply reliability of the entire power system.

Description

Technical Field

[0001] This application relates to the field of power, and in particular to a method, system, device, equipment and medium for controlling transformer inrush current. Background Technology

[0002] In power systems, transformers are core equipment, and their no-load closing operation is often accompanied by significant inrush current problems, which not only threaten the safety of the transformer itself, but also affect the stable operation of the power grid.

[0003] Existing methods for controlling transformer inrush current mainly include phase-selective closing technology, which involves controlling the circuit breaker to close at the zero-crossing point or a specific point of the voltage waveform, so that the transformer core flux approaches the steady-state value at the moment of closing, thus reducing saturation. This method does not fully consider the impact of the opening operation on the residual magnetism of the core, and only controls the closing point, which cannot effectively counteract the residual magnetism left by the previous opening operation.

[0004] In summary, providing a solution that can counteract the residual magnetism generated in the transformer core due to circuit breaker tripping, thereby improving the effectiveness of transformer inrush current suppression, is an urgent technical problem to be solved. Summary of the Invention

[0005] This application provides a method, system, device, equipment, and medium for controlling transformer inrush current, which effectively counteracts the residual magnetism of the transformer core, significantly suppresses the amplitude of inrush current, and thus ensures the safe and stable operation of the transformer and the power grid.

[0006] In a first aspect, embodiments of this application provide a method for controlling transformer inrush current. The method is applied to a phase-controlled closing module in a transformer inrush current control system. The system further includes a circuit breaker and a transformer. The method includes:

[0007] Obtain the tripping angle of the circuit breaker at the last tripping moment;

[0008] Based on the opening angle and the environmental parameters inside the circuit breaker, the target closing angle of the circuit breaker is determined.

[0009] Based on the target closing angle, the circuit breaker is controlled to close in order to suppress the inrush current of the transformer.

[0010] In one possible implementation, determining the target closing angle of the circuit breaker based on the opening angle and the environmental parameters inside the circuit breaker includes:

[0011] Obtain the temperature and humidity values ​​inside the circuit breaker;

[0012] Based on the opening angle, the residual magnetism generated after the circuit breaker opens is calculated;

[0013] Based on the residual magnetism and the preset flux balance constraint equation, the initial closing angle of the circuit breaker is calculated.

[0014] Based on the temperature and humidity values, the initial closing angle is corrected to obtain the target closing angle.

[0015] In one possible implementation, the step of correcting the initial closing angle based on the temperature value and the humidity value to obtain the target closing angle includes:

[0016] Based on the temperature value, the humidity value, and the initial closing angle, the closing angle correction term is obtained through a pre-trained closing angle correction model;

[0017] The sum of the initial closing angle and the closing angle correction term is determined as the target closing angle;

[0018] The closing angle correction model is obtained by training a neural network model based on the historical temperature value, historical humidity value, historical initial closing angle, and historical target closing angle of the circuit breaker.

[0019] In one possible implementation, obtaining the tripping angle of the circuit breaker at the last tripping moment includes:

[0020] Obtain the voltage and current signals of the circuit breaker at the time of its last trip;

[0021] The tripping angle is calculated based on the current signal and the voltage signal.

[0022] In one possible implementation, calculating the tripping angle based on the current signal and the voltage signal includes:

[0023] Based on the voltage signal and the current signal, the instantaneous phase of the voltage and the instantaneous phase of the current are calculated respectively using phase-locked loop technology;

[0024] The phase difference between the instantaneous phase of the voltage and the instantaneous phase of the current when the current signal drops from a non-zero value to zero is determined as the tripping angle.

[0025] In one possible implementation, the method further includes:

[0026] Based on the target closing angle, a closing operation command is generated;

[0027] The closing operation command is sent to the circuit breaker through the closing command output channel of the phase-controlled closing module, so as to drive the circuit breaker to complete the closing operation at the target closing angle.

[0028] Secondly, embodiments of this application provide a control device for transformer inrush current. The device is applied to a phase-controlled closing module in a transformer inrush current control system. The system further includes a circuit breaker and a transformer. The device includes:

[0029] The first processing module is used to obtain the opening angle of the circuit breaker at the last opening time;

[0030] The second processing module is used to determine the target closing angle of the circuit breaker based on the opening angle and the environmental parameters inside the circuit breaker.

[0031] The third processing module is used to control the circuit breaker to close based on the target closing angle, so as to suppress the inrush current of the transformer.

[0032] In one possible implementation, the second processing module is specifically used for:

[0033] Obtain the temperature and humidity values ​​inside the circuit breaker;

[0034] Based on the opening angle, the residual magnetism generated after the circuit breaker opens is calculated;

[0035] Based on the residual magnetism and the preset flux balance constraint equation, the initial closing angle of the circuit breaker is calculated.

[0036] Based on the temperature and humidity values, the initial closing angle is corrected to obtain the target closing angle.

[0037] In one possible implementation, the second processing module is further configured to:

[0038] Based on the temperature value, the humidity value, and the initial closing angle, the closing angle correction term is obtained through a pre-trained closing angle correction model;

[0039] The sum of the initial closing angle and the closing angle correction term is determined as the target closing angle;

[0040] The closing angle correction model is obtained by training a neural network model based on the historical temperature value, historical humidity value, historical initial closing angle, and historical target closing angle of the circuit breaker.

[0041] In one possible implementation, the first processing module is specifically used for:

[0042] Obtain the voltage and current signals of the circuit breaker at the time of its last trip;

[0043] The tripping angle is calculated based on the current signal and the voltage signal.

[0044] In one possible implementation, the first processing module is further configured to:

[0045] Based on the voltage signal and the current signal, the instantaneous phase of the voltage and the instantaneous phase of the current are calculated respectively using phase-locked loop technology;

[0046] The phase difference between the instantaneous phase of the voltage and the instantaneous phase of the current when the current signal drops from a non-zero value to zero is determined as the tripping angle.

[0047] In one possible implementation, the device further includes a fourth processing module for:

[0048] Based on the target closing angle, a closing operation command is generated;

[0049] The closing operation command is sent to the circuit breaker through the closing command output channel of the phase-controlled closing module, so as to drive the circuit breaker to complete the closing operation at the target closing angle.

[0050] Thirdly, embodiments of this application provide a control system for transformer inrush current, including: a circuit breaker, a transformer, and a phase-controlled closing module, wherein the phase-controlled closing module is used to execute the first aspect and / or various possible implementations of the first aspect.

[0051] Fourthly, embodiments of this application provide an electronic device, including: a memory and a processor;

[0052] The memory stores computer-executed instructions;

[0053] The processor executes computer execution instructions stored in the memory, causing the processor to perform the first aspect and / or various possible implementations of the first aspect as described above.

[0054] Fifthly, embodiments of this application provide a computer-readable storage medium storing computer-executable instructions, which, when executed by a processor, are used to implement the first aspect and / or various possible implementations of the first aspect.

[0055] In a sixth aspect, embodiments of this application provide a computer program product, including a computer program that, when executed by a processor, implements the first aspect and / or various possible implementations of the first aspect.

[0056] This application provides a method, system, device, equipment, and medium for controlling transformer inrush current. The method is applied to a phase-controlled closing module of a transformer inrush current control system. The system also includes a circuit breaker and a transformer. The method includes: first, obtaining the opening angle of the circuit breaker at the last opening moment; then, determining the target closing angle of the circuit breaker based on this opening angle and the internal environmental parameters of the circuit breaker; and finally, controlling the circuit breaker to perform a closing operation according to the target closing angle, thereby effectively suppressing the transformer's no-load closing inrush current. Through this method, the transient magnetic flux generated at the moment of closing is precisely canceled out in amplitude and direction with the residual magnetism remaining in the core after opening. This prevents the core from entering a deep saturation state at the magnetic flux level, effectively suppressing the inrush current. The winding electrodynamic impact and heat accumulation during the no-load closing process of the transformer are significantly reduced, helping to extend the service life of the transformer and circuit breaker. Simultaneously, it reduces the probability of maloperation of the main transformer differential protection due to inrush current, improving the safety and reliability of the entire power system operation. Attached Figure Description

[0057] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application.

[0058] Figure 1 A flowchart illustrating a method for controlling transformer inrush current provided in this application. Figure 1 ;

[0059] Figure 2 A flowchart illustrating a method for controlling transformer inrush current provided in this application. Figure 2 ;

[0060] Figure 3 A simplified no-load tripping equivalent circuit diagram of a transformer is provided for this application;

[0061] Figure 4 A schematic diagram of the structure of a transformer inrush current control system provided in this application;

[0062] Figure 5 A schematic diagram of the structure of a transformer inrush current control device provided in this application;

[0063] Figure 6 This is a schematic diagram of the structure of an electronic device provided in this application.

[0064] The accompanying drawings illustrate specific embodiments of this application, which will be described in more detail below. These drawings and descriptions are not intended to limit the scope of the concept in any way, but rather to illustrate the concept of this application to those skilled in the art through reference to particular embodiments. Detailed Implementation

[0065] Exemplary embodiments will now be described in detail, examples of which are illustrated in the accompanying drawings. When the following description relates to the drawings, unless otherwise indicated, the same numbers in different drawings denote the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with this application. Rather, they are merely examples of apparatuses and methods consistent with some aspects of this application.

[0066] The application background of this application is explained as follows:

[0067] In power systems, transformers are the core equipment for voltage transformation and energy transmission, and their safe and reliable operation is directly related to the power supply quality and stability of the entire power grid.

[0068] In actual operation, transformers must be switched on under no-load conditions before being connected to the grid. This involves first charging the transformer and then gradually connecting it to the load after the excitation transient process has ended and the operation has stabilized. This is to avoid the greater impact caused by the superposition of fault current and load current when switching on under load, and is a necessary measure to ensure the safety of power equipment and the power grid. However, when a transformer is switched on under no-load conditions, because the core magnetic flux cannot change abruptly, an inrush current with an amplitude several times or even more than ten times the rated current is often generated at the moment of switching on. This inrush current contains a large number of harmonics and DC components, which not only generate huge electrodynamic forces on the transformer windings, leading to cumulative effects of mechanical deformation and insulation damage, shortening equipment life, but also cause power quality problems such as voltage drops and waveform distortion, interfering with other equipment on the same grid. More seriously, its waveform characteristics are easily misjudged as internal faults by relay protection devices, causing circuit breakers to trip erroneously, resulting in switching failure or even expanding the power outage area, seriously threatening the safe and stable operation of the power grid. Therefore, the inrush current problem caused by no-load switching has become an unavoidable key technical challenge in the commissioning of transformers.

[0069] Existing transformer inrush current control methods mainly include phase-selective closing technology. The core idea of ​​this technology is that when a transformer is closed under no-load conditions, the residual magnetism in the core and the pre-induced magnetic flux determined by the power supply voltage at the moment of closing superimpose, easily causing the core to enter a saturated state, thus generating a large-amplitude inrush current. Therefore, phase-selective closing technology avoids core saturation by actively controlling the closing time. Specifically, this technology utilizes a circuit breaker phase-selective control device to monitor the voltage waveform phase in real time. Through precise calculation, the closing time of the circuit breaker's moving and stationary contacts is controlled at a specific phase angle of the voltage waveform. This ensures that the pre-induced magnetic flux established in the core by the power supply voltage at the moment of closing is exactly equal in magnitude and opposite in direction to the residual magnetism remaining in the core after the transformer is opened, thus canceling each other out. In this way, the total magnetic flux of the core after closing can directly enter or approach the normal steady-state operating magnetic flux level, avoiding excessive increase in magnetic flux during transient processes that could lead to core saturation, thereby suppressing the generation of inrush current at its source.

[0070] However, this method does not fully consider the impact of the tripping operation on the residual magnetism of the iron core. The moment when the transformer is de-energized (i.e. the tripping moment) determines the magnitude and direction of the residual magnetism of the iron core. The residual magnetism is a key initial condition affecting the inrush current when closing. Controlling only the closing point, i.e. attempting to control the closing phase angle so that the induced magnetic flux established after closing is exactly at a certain expected value, severs the physical connection between the two operation links of the transformer tripping and closing, and cannot effectively cancel the residual magnetism left by the previous tripping operation.

[0071] Specifically, each time a transformer is disconnected from the power grid, the forced interruption of the excitation current causes magnetic flux in the core to remain along the hysteresis loop, forming residual magnetism with a certain magnitude and direction. The specific state of this residual magnetism depends entirely on various random factors such as the phase angle of the voltage at the moment of opening, the amplitude of the current cut-off, and the arc-extinguishing performance of the circuit breaker, exhibiting a high degree of uncertainty and non-repeatability. Further complicating matters, slight differences in the operating sequence of circuit breakers in different phases can lead to different residual magnetisms remaining in the three-phase cores, potentially even being in drastically different states such as positive saturation, negative saturation, and zero residual magnetism. When the steady-state magnetic flux increment corresponding to the closing phase is unequal in amplitude and different in direction from the actual residual magnetism remaining in the core, they not only fail to cancel each other out but may even superimpose, causing the total magnetic flux in the core after closing to far exceed the saturation threshold, thereby generating an excitation inrush current more intense than that generated by random closing.

[0072] In addition, existing methods for controlling transformer inrush current include pre-magnetization and series resistance. Pre-magnetization involves applying a certain excitation current to the transformer core using an external device before the transformer is officially switched on, actively changing the magnetic flux state in the core to approach or reach a preset level conducive to suppressing inrush current. Series resistance, by introducing an appropriate resistor into the transformer's switching circuit, increases the total impedance of the circuit, thereby limiting the amplitude of the inrush current. Simultaneously, the introduction of the resistor accelerates the attenuation of the DC component in the transient magnetic flux, allowing the inrush current to subside more quickly.

[0073] In general, while both pre-magnetization and series resistance methods have achieved certain suppression effects in engineering practice, the former requires an additional independent pre-magnetization device and its control circuit, resulting in a complex system structure, high equipment costs, and extremely stringent requirements for control precision in coordinating the magnetization depth and closing phase, severely restricting its widespread application in large-capacity transformers and complex field conditions. The latter requires additional resistors and bypass switches, increasing the footprint and investment of primary equipment, and the selection of optimal resistance values ​​lacks unified engineering guidelines; improper resistance values ​​may even affect the normal charging of the transformer or prolong the transient process. More importantly, neither method fundamentally utilizes and controls the key link of the opening operation, which directly affects residual magnetism; they still focus only on the closing operation, exhibiting the same inherent logical limitations as the phase-selective closing technology.

[0074] In view of this, it is an urgent technical problem to be solved to provide a way to counteract the residual magnetism generated in the transformer core due to circuit breaker opening, improve the effectiveness of transformer inrush current suppression, and thus ensure the safe and stable operation of power equipment and power grid.

[0075] Based on the aforementioned technical problems, in the process of researching control methods for transformer inrush current, the inventors no longer isolatedly controlled only the closing point. Instead, they used the previous circuit breaker opening angle as the basis for the current circuit breaker closing angle and optimized the closing angle based on environmental factors to obtain the optimal closing angle. When the moving and stationary contacts of the circuit breaker move to this optimal closing angle, closing is performed. This ensures that the transient magnetic flux established in the iron core by the power supply voltage at the moment of closing is exactly equal in amplitude and opposite in direction to the residual magnetism left by the previous opening operation, thus canceling each other out (the combined magnetic flux is closer to 0). This allows the total magnetic flux of the iron core to directly enter the steady-state operating range during the entire closing process, avoiding saturation, thereby effectively suppressing the generation of inrush current when the transformer is closed under no-load conditions. Based on this, this application provides a control method, system, device, equipment, and medium for transformer inrush current.

[0076] The technical solution of this application and how it solves the above-mentioned technical problems will be described in detail below with specific embodiments. These specific embodiments can be combined with each other, and the same or similar concepts or processes may not be described again in some embodiments. The embodiments of this application will be described below with reference to the accompanying drawings.

[0077] Figure 1 A flowchart illustrating a method for controlling transformer inrush current provided in this application. Figure 1 This method is applied to the phase-controlled closing module in the transformer inrush current control system. The inrush current control system also includes a circuit breaker and a transformer, such as... Figure 1 As shown, the method includes:

[0078] S101: Obtain the opening angle of the circuit breaker at the last opening time.

[0079] The phase-controlled closing module, as the implementation carrier, is typically electrically connected to the circuit breaker and transformer. The circuit breaker is the switching device that performs opening and closing actions; changes in its mechanical contact state correspond to the connection and disconnection of the transformer from the power grid. The transformer is the object to be put into operation under no-load conditions. After the circuit breaker's previous opening, its core retains a state corresponding to the magnetic flux at the moment of opening; therefore, the previous opening angle can be used as an input for subsequent control. In practice, the phase-controlled closing module saves the record of the most recent opening event and retrieves this record when it receives a request to put the transformer into operation under no-load conditions. The opening angle refers to the electrical phase position of the voltage waveform of the external power network connected to the primary side (high-voltage side) of the transformer at the moment of the previous opening. It is measured in degrees and continuously ranges from 0° to 360°, where 0° corresponds to the positive zero-crossing point of the voltage waveform, 90° corresponds to the positive peak point, 180° corresponds to the negative zero-crossing point, and 270° corresponds to the negative peak point.

[0080] In one possible implementation, the opening angle of the circuit breaker at the last opening moment can be obtained by acquiring the voltage and current signals of the circuit breaker at the last opening moment, and then calculating the opening angle based on the voltage and current signals.

[0081] Among them, the voltage signal refers to the voltage on the power supply side of the circuit breaker at the last time the circuit breaker was opened, that is, the voltage on the bus or transmission line to which the transformer is connected. It can be collected by a potential transformer (PT) connected in parallel near the bus side. Since the voltage transformer is always connected in parallel to the power grid bus, its secondary side can continuously output a voltage signal that is strictly synchronized with the real-time phase of the power grid, regardless of whether the circuit breaker is in the closed or open state. This provides a reference standard for the accurate calculation of the opening angle that is not affected by the circuit breaker's operating state.

[0082] The current signal refers to the transient current flowing through the primary winding of the transformer at the moment the circuit breaker was last opened. It can be acquired by a current transformer (CT) connected in series between the circuit breaker and the transformer. When the circuit breaker is in the closed state, the current transformer can reflect the instantaneous changes in the transformer's no-load excitation current or load current in real time. When the circuit breaker performs an opening operation, the current signal gradually decays from the initial power frequency excitation current value until the arc is finally extinguished at the current zero-crossing point, and the current signal suddenly drops to zero.

[0083] The phase-controlled closing module precisely locks the final moment when the excitation current is actually cut off (i.e., the transient state when the circuit is completely disconnected) by capturing the instant when the current signal changes from non-zero to zero. Then, by comparing the timing of this cut-off moment with the aforementioned bus-side voltage signal, the precise voltage phase angle corresponding to that moment, i.e., the opening angle, can be calculated.

[0084] By incorporating the circuit breaker's tripping angle at the time of the previous tripping into the control link, the subsequent closing angle no longer depends solely on the current voltage phase. This allows for the precise calculation of the unique closing phase corresponding to the transient flux with the same amplitude but opposite direction as the residual magnetism left from the previous tripping. Consequently, the closing strategy shifts from "passively adapting to random residual magnetism" to "actively compensating for known residual magnetism," ensuring that the total magnetic flux of the iron core can accurately enter the steady-state operating region at the moment of closing, thus avoiding saturation and improving the reliability of inrush current suppression.

[0085] S102: Determine the target closing angle of the circuit breaker based on the opening angle and the internal environmental parameters of the circuit breaker.

[0086] In this step, environmental parameters are used to reflect the impact of the internal environmental conditions of the circuit breaker on the control results. These parameters may include the humidity and temperature values ​​inside the circuit breaker. The humidity value can be detected by a humidity sensor installed on the circuit breaker, and the temperature value can be detected by a temperature sensor installed on the circuit breaker. The target closing angle refers to the specific electrical phase position at which each phase contact of the circuit breaker should complete the closing action during the transformer no-load closing operation, in order to suppress inrush current. This is determined by comprehensive calculation based on the circuit breaker's opening angle at the time of the previous opening and the current environmental parameters. The angle is expressed in degrees and ranges from 0° to 360°.

[0087] As the target of inrush current suppression, the magnitude of the inrush current during no-load closing of the transformer is related to the closing phase. Therefore, the determination of the target closing angle is essentially a process of back-calculating a suitable voltage closing phase based on the opening angle and environmental parameters. In specific implementation, the phase-controlled closing module calculates the initial closing angle based on the opening angle of the circuit breaker at the last opening moment. Subsequently, based on the internal temperature and humidity values ​​of the circuit breaker, the initial closing angle is corrected to obtain the target closing angle. After correction, the target closing angle is normalized to an angle range of one fundamental cycle (0° to 360°). In one possible embodiment, the phase-controlled closing module continuously monitors the internal temperature and humidity values ​​of the circuit breaker. When the detected humidity or temperature value exceeds a preset humidity threshold or a preset temperature threshold, the correction process is re-executed and the target closing angle is updated in real time.

[0088] By incorporating the historical state information reflected by the opening angle and the environmental parameters of the circuit breaker into the calculation of the target closing angle, the resulting target closing angle can simultaneously characterize the historical state requirements and the correction amount of the field operating conditions. This ensures that the final calculated target closing angle not only carries the physical memory of the actual residual magnetism of the iron core, but also eliminates the comprehensive influence of field environmental parameters such as temperature and humidity on the mechanical characteristics of the circuit breaker. This ensures that the instantaneous magnetic flux matching of the circuit breaker during closing is optimal under different environments, and improves the environmental adaptability, operating condition robustness and long-term operational reliability of the inrush current suppression strategy.

[0089] S103: Based on the target closing angle, control the circuit breaker to close in order to suppress the inrush current of the transformer.

[0090] This step is the final execution stage of the transformer inrush current control method. It is used to convert the target closing angle determined in the previous steps into a physical action command that the circuit breaker operating mechanism can execute, thereby effectively suppressing the inrush current in the actual closing operation.

[0091] In one possible implementation, controlling the circuit breaker to close based on the target closing angle can be achieved in the following way:

[0092] Based on the target closing angle, a closing operation command is generated; the closing operation command is sent to the circuit breaker through the closing command output channel of the phase-controlled closing module to drive the circuit breaker to complete the closing operation at the target closing angle.

[0093] The closing operation command is an electrical pulse signal with a definite issuance time and specific pulse width, generated after timing logic operations based on parameters such as the calculated target closing angle, the real-time phase of the current bus voltage, and the inherent operating time of the circuit breaker. This closing operation command is not a continuous level signal, but a pulse-type drive signal triggered at a precisely calculated time point. It is used to activate the excitation circuit of the circuit breaker closing coil, causing the coil to generate electromagnetic driving force to actuate the operating mechanism. The closing command output channel refers to the physical signal transmission path in the phase-controlled closing module specifically used to output the closing operation command. Its starting point is the pulse output port of the digital signal processing unit inside the module, and its ending point is the closing coil power input terminal on the circuit breaker terminal block. The hardware configuration of this channel typically includes opto-isolation circuits, power amplifier circuits, output relays, and corresponding terminals. It usually has stable transmission delay characteristics, that is, the total delay time from the generation of the pulse signal to the closing of the relay contacts and the delivery of driving energy to the circuit breaker terminal block must be a fixed and repeatable known quantity. This delay will be included in the calculation of the pre-compensation for the closing command. Any phase shift caused by the instability of the channel delay will reduce the closing control accuracy.

[0094] It should be noted that the closing operation command is not issued at the instant the target closing angle is reached, but rather in advance. This is because there is an inherent action delay between the circuit breaker receiving the closing command and the actual mechanical closing of its moving and stationary contacts. This delay is determined by factors such as the type of circuit breaker's operating mechanism, the energy storage state of the operating spring, ambient temperature, and hydraulic or pneumatic pressure. Therefore, when generating the command, the phase-controlled closing module uses the inherent action time of the circuit breaker as a pre-compensation amount. A corresponding amount of time is taken before the target closing angle arrives, and the closing operation command is sent to the circuit breaker's closing coil drive circuit via the closing command output channel, ensuring that the actual closing moment of the circuit breaker contacts falls precisely at the target closing angle of the system voltage waveform.

[0095] Upon receiving the closing operation command, the circuit breaker closing coil drive circuit drives the operating mechanism to move the moving contacts. After a predetermined action delay time, the contacts close, and the transformer primary winding connects to the power grid at this precise moment. The transient magnetic flux generated at the instant of closing precisely cancels out the residual magnetism remaining in the iron core, effectively suppressing the generation of inrush current. The entire process, from command generation to pulse transmission to mechanical action completion, effectively ensures the timeliness and reliability of the closing operation. This ensures, in engineering practice, that every closing operation is precisely executed at the target angle, effectively canceling out the transient magnetic flux and the residual magnetism in the iron core, thus suppressing inrush current at its source.

[0096] The transformer inrush current control method provided in this application uses a phase-controlled closing module as the execution subject. By establishing a physical connection between the transformer opening operation and the subsequent closing operation, it fundamentally changes the open-loop control mode of traditional phase-selective closing technology, which only isolates the closing point. Specifically, this involves: first, obtaining the opening angle of the circuit breaker at the last opening moment; then, based on this opening angle and the internal temperature and humidity values ​​of the circuit breaker, comprehensively calculating and determining the target closing angle of the circuit breaker; finally, based on this target closing angle, fully considering the inherent operating time of the circuit breaker and the transmission delay of the control circuit, generating a closing operation command with a precise issuance time and a specific pulse width in advance, and sending it to the circuit breaker closing coil drive circuit through the closing command output channel configured in the phase-controlled closing module, so that the circuit breaker contacts complete the closing at the instant when the voltage waveform on the bus side reaches the target closing angle. The transient magnetic flux generated during closing is equal in amplitude and opposite in direction to the residual magnetism left after opening, and the two achieve precise cancellation. The total magnetic flux of the iron core directly enters the steady-state operating range and avoids saturation, thereby suppressing the generation of inrush current from the source without adding additional hardware equipment.

[0097] By employing the above method, the determination of the target closing time simultaneously considers historical state information from the previous opening and current environmental changes, thus controlling the closing process. Ultimately, this ensures that the transient magnetic flux generated at the moment of closing maintains a precise cancellation relationship with the residual magnetism of the iron core, strictly limiting the inrush current amplitude to the normal excitation current level. This effectively avoids winding electrodynamic impacts and cumulative insulation damage caused by inrush current, improving the success rate of transformer no-load closing and the safety of power grid equipment operation, providing technical support for the long-term stable and reliable operation of the power system. Furthermore, this method is easily expandable on existing phase-controlled closing modules, with relatively low implementation costs, helping to reduce protection malfunctions and improve power grid operation safety and equipment lifespan.

[0098] Based on the above embodiments, in S101: the tripping angle is calculated based on the current signal and the voltage signal, specifically including:

[0099] (1) Based on the voltage signal and the current signal, the instantaneous phase of the voltage and the instantaneous phase of the current are calculated by phase-locked loop technology.

[0100] Instantaneous phase refers to the specific position of a sinusoidal AC voltage or current waveform at a given moment within its complete cycle (0° to 360°). Unlike amplitude parameters such as RMS or peak value, instantaneous phase characterizes the dynamic position of the waveform over time. Since voltage and current signals are continuous signals that vary sinusoidally with time, their instantaneous phase is actually linearly related to time. Under the condition of a constant fundamental frequency, the phase changes exactly 360° after each complete cycle. However, in actual power systems, voltage and current waveforms are often affected by factors such as harmonics, noise, frequency shifts, and transient disturbances. The phase information obtained directly through simple methods such as zero-crossing detection has limited accuracy and is easily affected by interference. Therefore, phase-locked loop (PLL) technology can be used to achieve high-precision phase tracking and extraction.

[0101] Specifically, when calculating the instantaneous voltage and current phases using phase-locked loop (PLL) technology based on voltage and current signals, a reference signal with a frequency close to the input signal (voltage / current signal) is first generated by a voltage-controlled oscillator (VCO). This reference signal and the input signal are simultaneously fed into a phase detector for phase comparison. The phase detector outputs the phase difference between the two signals. This error signal, after being filtered by a loop filter to remove high-frequency components, is fed back to the VCO as a control voltage, adjusting its output frequency and phase. This process continuously brings the reference signal closer to the input signal until their frequencies are perfectly synchronized and the phase difference is constant at zero or a fixed small value, at which point the VCO enters a locked state. In the locked state, the VCO's output signal frequency is completely synchronized with the input signal, and its instantaneous phase represents the real-time phase of the input signal, thus achieving accurate extraction of the input signal phase. Applying this technology to the voltage signal channel and the current signal channel respectively allows for the separate acquisition of the instantaneous voltage and current phases.

[0102] (2) The phase difference between the instantaneous phase of the voltage and the instantaneous phase of the current when the current signal drops from a non-zero value to zero is determined as the opening angle.

[0103] The instantaneous voltage phase provides a continuous phase reference unaffected by the circuit breaker's switching state for subsequent tripping angle calculations, while the instantaneous current phase is used to detect sudden changes in current amplitude. When the current signal suddenly drops from a non-zero value to zero, the critical moment when the excitation current is forcibly cut off is precisely calibrated. At this moment, the magnetic flux in the core is at a specific instantaneous value. After the current cut-off occurs, this magnetic flux will no longer be driven by the external voltage, but will fall back along the hysteresis loop of the ferromagnetic material from the current operating point, eventually settling at a certain residual magnetic flux density level. Therefore, this abrupt change directly determines the magnitude and direction of the residual magnetism in the core after tripping, and is the initial boundary condition for the entire residual magnetism formation process.

[0104] Therefore, when the current signal is detected to suddenly drop from a non-zero value to zero, the instantaneous voltage phase and current phase output by the phase-locked loop are read at that moment. The instantaneous voltage phase indicates the electrical position of the bus-side voltage waveform at the current moment, and the instantaneous current phase indicates the position of the current waveform at that moment. Subtracting the instantaneous current phase from the instantaneous voltage phase yields a difference that reflects the phase relationship between the voltage and current at that moment. Since the current waveform typically lags the voltage waveform by a certain angle under transformer no-load excitation, this difference is numerically represented as a definite positive or negative angle. However, the result of a simple difference calculation may be outside the range of 0° to 360° or negative. Therefore, normalization is required based on the physical meaning of the phase difference: if the difference is negative, add 360° to the difference; if the difference is greater than 360°, subtract 360° from the difference, until the result is constrained to the range of 0° to 360°. This angle value obtained after normalization is determined as the accurate tripping angle at the last tripping moment. The tripping angle physically represents the exact phase position of the system voltage waveform at the moment of current cutoff during tripping. This position directly maps the magnitude and direction of the residual magnetism in the iron core after tripping, providing a unique and definite initial boundary condition for the formulation of subsequent closing strategies.

[0105] Since the instantaneous voltage phase is continuously provided by the voltage transformer connected to the power grid bus, it has continuity and stability. The instantaneous current phase is tracked in real time by the current transformer and a calibration signal is provided at the moment of current cutoff. The difference between the two is calculated based on the synchronous sampling data at the same moment, which effectively eliminates the phase deviation caused by timing misalignment or inconsistent data sources, and ensures the accuracy and reliability of the tripping angle calculation results.

[0106] Figure 2 A flowchart illustrating a method for controlling transformer inrush current provided in this application. Figure 2 , Figure 3 This application provides a simplified no-load tripping equivalent circuit diagram for a transformer. Based on the above embodiment, in step S102: the target closing angle of the circuit breaker is determined based on the tripping angle and the internal environmental parameters of the circuit breaker, specifically including:

[0107] S201: Obtain the internal temperature and humidity values ​​of the circuit breaker.

[0108] The internal temperature of a circuit breaker is a comprehensive quantitative characterization of the thermodynamic state of key components and media within the circuit breaker. Specifically, it includes the thermodynamic temperature of the insulating medium (such as SF6 gas, dry air, or a N2 mixture) inside the arc-extinguishing chamber, the body temperature of the main circuit conductive circuit (especially the contact surfaces of the moving and stationary contacts and the conductive rod), and the ambient air temperature within the operating mechanism. Generally, the internal temperature of a circuit breaker refers to the body temperature of the main circuit conductive circuit, which is the point where heat generation is most prominent and faults are most likely to occur. The internal humidity of a circuit breaker refers to the actual water vapor content in the insulating medium filling the arc-extinguishing chamber or operating mechanism box, usually characterized as a relative humidity percentage or, more precisely, the dew point temperature. The relative humidity percentage reflects the ratio of the partial pressure of water vapor in the insulating medium at the current temperature to the saturated water vapor pressure at that temperature, while the dew point temperature represents the critical temperature at which water vapor begins to condense into liquid water when the gas is cooled.

[0109] As mentioned in S102, temperature and humidity values ​​can be collected by temperature and humidity sensors installed inside the circuit breaker, respectively. These values ​​can be used to correct the mechanical action delay deviation of the circuit breaker caused by environmental temperature drift, and to apply a safety margin constraint to the tolerance threshold of transient overvoltage during closing due to the decrease in the electrical strength of the insulating medium in a high humidity environment.

[0110] S202: Based on the opening angle, the residual magnetism generated after the circuit breaker opens is calculated.

[0111] In this process, remanence refers to the magnetic flux density that remains inside the transformer core after the external excitation power supply is completely cut off and the magnetic field strength drops to zero. Its essence stems from the inherent hysteresis characteristics of ferromagnetic materials. Macroscopically, remanence in the transformer core manifests as a magnetic flux of a certain magnitude and direction still remaining within the core.

[0112] Specifically, the interruption of the excitation current caused by the circuit breaker's tripping operation is essentially an interruption of the magnetization process. The magnetic flux in the core retreats along the hysteresis loop from a certain flux density value at the moment of tripping towards the zero magnetic field strength point, eventually settling at the residual flux density point. The value at this point is the actual residual magnetism remaining in the core after the tripping operation. The magnitude of the residual magnetism is usually expressed as a percentage of the saturation flux density. A typical power transformer core may retain 20% to 80% saturation residual magnetism after tripping. Since the existence of residual magnetism is one of the fundamental causes of inrush current, when the transformer is closed again, if the transient flux established by the bus voltage is in the same direction as the existing residual magnetism in the core, their superposition can easily exceed the core's saturation flux density, causing the core to enter a deep saturation state, thereby exciting a large-amplitude inrush current. Therefore, the accurate initial magnetic state of the core after tripping can be obtained by calculating the residual magnetism, and this initial magnetic state can be used as a direct input parameter for subsequent closing strategies.

[0113] like Figure 3 As shown, the residual magnetism formation mechanism and quantitative calculation logic are further explained by combining the equivalent circuit of transformer no-load tripping. Specifically, at t=0, circuit breaker Q performs a tripping operation, with a tripping angle of... Bus voltage before tripping The equivalent capacitance to ground C of the transformer and the equivalent resistance R of the transformer core loss are affected. m and the excitation equivalent inductance L m The excitation branch formed by the three components connected in parallel has a total input current of Decomposed into capacitive current Iron core loss current With magnetizing inductor current The excitation inductor L flows through it. m of It is the core excitation current that establishes the magnetic flux inside the iron core. When the circuit breaker trips and disconnects the external power supply circuit at t=0, the magnetic field strength applied by the external power supply instantaneously returns to zero, but the excitation inductance L... m The corresponding iron core ferromagnetic material cannot release all magnetic flux instantaneously due to its hysteresis characteristics, thus tripping the excitation current. The instantaneous magnetic flux value will decay along the hysteresis loop of the iron core to the residual magnetic flux corresponding to zero magnetic field, which is the residual magnetism of the iron core to be solved.

[0114] After circuit breaker Q completes the tripping and disconnects the external power supply at t=0, the equivalent capacitance to ground of the transformer C and the equivalent resistance of the transformer core loss R are... m and the excitation equivalent inductance L m This forms a passive parallel circuit without external excitation, where the current conservation relationship is satisfied at the parallel nodes, i.e., the capacitor current. Iron core loss current With magnetizing inductor current The sum of the three is always equal to zero.

[0115] It is known that the volt-ampere characteristic of a capacitor, the ohmic characteristic of a resistor, and the integral volt-ampere characteristic of an inductor can be expressed as:

[0116]

[0117] in, This refers to the real-time instantaneous voltage across capacitor C in the passive parallel circuit after circuit breaker Q trips and disconnects the external power supply. This is due to the transformer's equivalent ground capacitance C and the transformer core loss equivalent resistance R. m and the excitation equivalent inductance L m When the three are connected in parallel, the voltage is equal to the equivalent resistance R of the transformer core loss. m and the excitation equivalent inductance L m The terminal voltages at both ends, and .

[0118] Combining the volt-ampere characteristics of capacitors, the ohmic characteristics of resistors, the integral volt-ampere characteristics of inductors, and the current conservation relationship, we can obtain:

[0119]

[0120] To eliminate the integral operations in the inductance term and obtain a time-domain equation containing only the differential form of the capacitor voltage, we take the first derivative of both sides of the equation with respect to time t, and then simplify and reorganize all terms (while dividing by the coefficient C) to obtain:

[0121]

[0122] Solving this differential equation yields the discriminant ( )for:

[0123]

[0124] Since the equivalent capacitance to ground of a transformer typically ranges from C=100 to 5000pF, it is much smaller than the equivalent resistance R of the transformer core loss. m and the excitation equivalent inductance L m ,therefore This differential method has two characteristic roots. and , can be represented as:

[0125]

[0126] The general solution of the second-order homogeneous differential equation (with two distinct real roots) is as follows: Where A and B are undetermined constants, which need to be substituted into the initial boundary conditions at the time of circuit breaker opening t=0 to solve the problem.

[0127] Before the circuit breaker trips, the transformer operates under no-load steady-state conditions, and the busside voltage... , among which, U m Indicates voltage amplitude; It represents the power frequency angular frequency, which is the equivalent rotational angular velocity of AC electromagnetic quantities.

[0128] At the instant of circuit breaker tripping (t=0), the boundary conditions are: (1) The initial voltage of the capacitor (voltage at the parallel branch terminals) is: (2) The initial value of the first derivative of the capacitor voltage is obtained from the capacitor current. Since the steady-state excitation current lags the voltage by 90°, it can be concluded that:

[0129]

[0130] Substituting t=0 into the general solution It can be known that:

[0131]

[0132] The solution yields:

[0133]

[0134] Because the excitation circuit parameters of the power transformer satisfy: loss resistance R m Maximum, weak core damping, characteristic root The absolute value is much greater than exponent term The attenuation rate is extremely fast, and it occurs within a very short time after the circuit breaker is tripped. Since the decay rate approaches zero, this term can be ignored in engineering calculations, and only the principal component with slower decay is retained. Therefore, an approximate relationship exists:

[0135]

[0136] According to Faraday's law of electromagnetic induction, the induced electromotive force in the primary winding of a transformer and the magnetic flux in the core satisfy the following:

[0137]

[0138] Where N1 represents the number of turns in the primary winding of the transformer; u represents the voltage across the winding (which, after opening, is equal to the voltage of the parallel branch capacitor). ); This represents the total instantaneous magnetic flux passing through the main magnetic circuit of the iron core. Magnetic flux It can be represented as:

[0139]

[0140] The steady-state value at which the integral converges after the circuit energy is completely dissipated and the voltage decays to 0 after the circuit is opened is the residual magnetic flux of the iron core. Remanence, or remanence, can be defined as magnetic flux. The limiting result is:

[0141]

[0142] Based on the approximate relationship determined above, we can conclude that:

[0143]

[0144] Under overdamped circuit conditions, characteristic roots The infinite-finite exponential integral converges:

[0145]

[0146] Further results were obtained:

[0147]

[0148] S203: Based on residual magnetism and the preset flux balance constraint equation, the initial closing angle of the circuit breaker is calculated.

[0149] In this step, the flux balance constraint equation is a mathematical equation constructed with the goal of preventing the total flux of the iron core from saturating significantly on one side after the circuit breaker is closed. The core constraint logic is that the transient DC bias flux generated at the moment of closing is equal in amplitude and opposite in polarity to the residual magnetism reserved in the iron core. By substituting the residual magnetism derived from the opening angle into the flux balance constraint equation and solving it simultaneously, the initial closing angle of the circuit breaker that can achieve the mutual cancellation of flux and suppress the inrush current effect can be calculated. This initial closing angle is the core phase control parameter for the circuit breaker to perform phase selection closing operation.

[0150] Based on Faraday's law of electromagnetic induction, neglecting the leakage resistance and voltage drop of the winding, the voltage u1 at the primary winding terminals of the transformer is approximately equal to the induced electromotive force e1 of the primary winding, depending on the closing angle. The induced electromotive force in each phase can be expressed as:

[0151]

[0152] Therefore, we can conclude that:

[0153]

[0154] Define the rated magnetic flux amplitude of the transformer. ,therefore, C represents the integration constant.

[0155] At the moment of closing (t=0), the residual magnetism generated by the opening is pre-retained inside the iron core. ,but Therefore, we can conclude that:

[0156]

[0157] In this formula, This refers to steady-state alternating magnetic flux, which is permanently alternating and exists over a long period. What truly causes the flux to exceed the limit and generate inrush current is the superposition of the latter two DC components, i.e., the transient DC bias magnetic flux. With remanence Therefore, the initial closing angle of the circuit breaker needs to be determined. That is to let (Magnetic flux balance constraint equation) to counteract DC bias and suppress core saturation at its source. Therefore, we can obtain:

[0158]

[0159] Therefore, the solution yields:

[0160]

[0161] S204: Based on temperature and humidity values, the initial closing angle is corrected to obtain the target closing angle.

[0162] The initial closing angle is a theoretical closing angle calculated from the opening angle based on the principle of magnetic flux cancellation. Its validity rests on the assumption that the circuit breaker's mechanical operating characteristics are fixed and the insulating medium is in a standard state. However, in actual operating conditions, temperature changes alter the DC resistance of the closing coil and the viscosity coefficient of the lubricating oil in the operating mechanism. This results in a temperature-dependent mechanical action delay between the issuance of the closing command and the actual contact closure. Under high humidity conditions, the breakdown voltage of the gas is significantly reduced. If this transient overvoltage is superimposed on the high humidity environment, it may induce surface discharge or even flashover. If not corrected in time, the theoretically calculated initial closing angle will exhibit a fixed phase lead or lag deviation during actual execution due to the delay, making it difficult to effectively counteract the residual magnetism of the transformer core.

[0163] In one possible implementation, the initial closing angle is corrected based on temperature and humidity values ​​to obtain a closing angle correction term, and the sum of the initial closing angle and the closing angle correction term is determined as the target closing angle. Specifically, this may include:

[0164] Based on temperature, humidity and initial closing angle, the target closing angle is obtained through a pre-trained closing angle correction model. The closing angle correction model is obtained by training a neural network model based on the circuit breaker's historical temperature, humidity, initial closing angle and target closing angle.

[0165] Specifically, the neural network model can be a back propagation (BP) neural network model, whose core idea is to continuously adjust the connection weights inside the network through back propagation of errors. A typical BP neural network consists of an input layer, a hidden layer, and an output layer.

[0166] For example, the number of neurons in the input layer of the BP neural network can be set to 3, with each neuron corresponding to one data point. These data points are used to receive the circuit breaker's temperature value, humidity value, and the theoretical initial closing angle determined based on the opening angle. This is the starting point for the closing angle correction model to correct the initial closing angle.

[0167] The number of neurons in the hidden layer can be set to 3. Each neuron in the input layer receives an input value that connects to every neuron in the hidden layer, forming nine data pathways. Each of these nine pathways is assigned an independent connection weight, determining the degree of influence of each input feature on subsequent calculations. When an input value (such as temperature) is transmitted along a pathway to the first neuron in the hidden layer, it is first multiplied by the weight corresponding to that pathway. Then, the products of the three input values ​​multiplied by their respective weights are summed within that neuron, and a bias term specific to that neuron is added, completing a linear weighted summation. This linear weighted summation result undergoes a non-linear transformation using an activation function (Sigmoid or ReLU), and the resulting value is the final output value of the hidden layer neuron. Similarly, the other two hidden layer neurons calculate their respective output values ​​in the exact same way, using their own independent weights and biases. However, due to different weight configurations, the combinations of input features they focus on and extract differ.

[0168] Subsequently, the output values ​​of these three neurons in the hidden layer will serve as the input to the output layer. The output layer has only one neuron, and its operation is similar to that of the neurons in the hidden layer. It first multiplies the three received values ​​by their respective connection weights and then sums them, adds its own bias term, and finally passes them through an activation function (usually a linear function, such as the identity mapping function) to obtain the closing angle correction term. This closing angle correction term is the difference offset between the corrected target closing angle and the initial closing angle. Adding the closing angle correction term to the initial closing angle gives the target closing angle.

[0169] In the process of pre-training the BP neural network model, the historical dataset, including historical temperature values, historical humidity values, historical initial closing angles, and historical target closing angles, is first preprocessed. Preprocessing includes at least one of outlier detection, missing value handling, standardization, and normalization. Then, the preprocessed historical dataset D is divided into a training set D. train Validation set D val and test set D test (D=D) train ∪D val ∪D test Optionally, the partitioning ratio can be 14:3:3, or 8:1:1, etc., and then the training set D is used. train The BP neural network model is trained, and the loss error between the predicted closing angle and the historical target closing angle is calculated layer by layer through the backpropagation algorithm. The connection weights and bias parameters of each layer of the network are iteratively updated according to the gradient descent rule. After each round of training, the generalization ability of the model is verified using a validation set. The iteration is repeated until the loss value of the validation set tends to be stable and there is no significant decrease. Finally, the closing angle correction model is obtained.

[0170] It should be noted that the above model is only an exemplary structure, especially the setting of the number of neurons in each layer, which is only used to illustrate the general architecture of the closing angle correction model and does not constitute a limitation on the actual model parameters.

[0171] In another possible implementation, a closing angle compensation function can be fitted based on historical temperature values, historical humidity values, historical initial closing angles, and historical target closing angles, with the circuit breaker's temperature and humidity values ​​as independent variables: By substituting the real-time temperature and humidity values ​​of the circuit breaker into the closing angle function, the angle compensation value can be calculated. Finally, the sum of the initial closing angle and the compensation value of that angle is taken as the target closing angle.

[0172] The transformer inrush current control method provided in this application first obtains the temperature and humidity values ​​inside the circuit breaker using temperature and humidity sensors installed inside the circuit breaker; then, it calculates the residual magnetism remaining in the iron core after the circuit breaker is opened based on the opening angle; next, it substitutes the calculated residual magnetism into a preset magnetic flux balance constraint equation. The core constraint logic of this equation is that the transient DC bias magnetic flux generated at the moment of closing is equal in amplitude and opposite in polarity to the residual magnetism pre-reserved in the iron core. By solving the equation simultaneously, the initial closing angle that can achieve mutual cancellation of magnetic fluxes is calculated; finally, using a pre-trained closing angle correction model or a fitted closing angle compensation function, the initial closing angle is nonlinearly corrected using the temperature and humidity values ​​as inputs to obtain the correction term of the initial closing angle. Finally, the correction term is superimposed with the initial angle to obtain the target closing angle.

[0173] The above method enables the circuit breaker to be precisely controlled to close near the optimal closing angle. The transient magnetic flux generated completely or significantly cancels out the steady-state residual magnetism remaining after the tripping. Throughout the process, the excitation current will be maintained at a low level close to steady state, significantly reducing the amplitude and duration of the transformer no-load closing excitation inrush current.

[0174] Figure 4 A schematic diagram of a transformer inrush current control system provided in this application is shown below. Figure 4 As shown, the control system for the transformer inrush current includes: a circuit breaker, a transformer, and a phase-controlled closing module. In addition, the system also includes a voltage transformer and a current transformer.

[0175] Specifically, the transformer inrush current control system relies on the coordinated operation of the high-voltage primary main circuit and the secondary measurement and control signal circuit. The primary side includes a high-voltage bus / line as the power transmission carrier, responsible for delivering high-voltage power to the downstream power transformer. A parallel voltage transformer is used to collect real-time bus voltage signals, and a current transformer connected in series between the circuit breaker and the transformer collects real-time load current and inrush current signals from the main circuit. The core primary equipment is the high-voltage circuit breaker, which performs the circuit switching function. Its internal mechanism can receive closing operation commands from the phase-controlled closing module to complete precise phase closing operations. The downstream three-winding power transformer is prone to generating inrush current during the closing process, and is also the target of this inrush current control method. The core secondary equipment is the phase-controlled closing module, used to execute the above method. The specific implementation process can be found in the above method embodiment, and its implementation principle and technical effects are similar, so it will not be repeated here. In addition to the closing command output channel, the phase-controlled closing module also includes a closing command input channel, a closing command input channel, and a closing command input channel, which are used to receive remote closing and opening operation commands issued by the background or local area.

[0176] Figure 5 This application provides a schematic diagram of a control device for transformer inrush current. This device is applied to the phase-controlled closing module in a transformer inrush current control system. The control system also includes a circuit breaker and a transformer. Figure 5 As shown, the transformer inrush current control device 50 provided in this embodiment includes:

[0177] The first processing module 501 is used to obtain the opening angle of the circuit breaker at the last opening time;

[0178] The second processing module 502 is used to determine the target closing angle of the circuit breaker based on the opening angle and the environmental parameters inside the circuit breaker.

[0179] The third processing module 503 is used to control the circuit breaker to close based on the target closing angle in order to suppress the inrush current of the transformer.

[0180] In one possible implementation, the second processing module 502 is specifically used for:

[0181] Obtain the internal temperature and humidity values ​​of the circuit breaker;

[0182] Based on the opening angle, the residual magnetism generated after the circuit breaker opens is calculated;

[0183] Based on residual magnetism and the preset flux balance constraint equation, the initial closing angle of the circuit breaker is calculated.

[0184] Based on the temperature and humidity values, the initial closing angle is corrected to obtain the target closing angle.

[0185] In one possible implementation, the second processing module 502 is further used for:

[0186] Based on temperature, humidity and initial closing angle, the closing angle correction term is obtained through a pre-trained closing angle correction model;

[0187] The sum of the initial closing angle and the closing angle correction term is determined as the target closing angle;

[0188] Among them, the closing angle correction model is obtained by training the neural network model based on the historical temperature value, historical humidity value, historical initial closing angle and historical target closing angle of the circuit breaker.

[0189] In one possible implementation, the first processing module 501 is specifically used for:

[0190] Obtain the voltage and current signals of the circuit breaker at the time of its last trip;

[0191] The tripping angle is calculated based on the current and voltage signals.

[0192] In one possible implementation, the first processing module 501 is further configured to:

[0193] Based on voltage and current signals, the instantaneous phase of voltage and the instantaneous phase of current are calculated separately using phase-locked loop (PLL) technology.

[0194] The phase difference between the instantaneous phase of the voltage and the instantaneous phase of the current when the current signal drops from a non-zero value to zero is determined as the tripping angle.

[0195] In one possible implementation, the transformer inrush current control device 50 further includes a fourth processing module 504, used for:

[0196] Generate closing operation instructions based on the target closing angle;

[0197] The closing operation command is sent to the circuit breaker through the closing command output channel of the phase-controlled closing module, so as to drive the circuit breaker to complete the closing operation at the target closing angle.

[0198] The transformer inrush current control device provided in this embodiment can execute the method provided in the above method embodiment. Its implementation principle and technical effect are similar, and will not be described again in this embodiment.

[0199] Figure 6 A schematic diagram of the structure of an electronic device provided in this application, such as... Figure 6As shown, the electronic device 60 provided in this embodiment includes at least one processor 601 and a memory 602. Optionally, the electronic device 60 further includes a communication component 603. The processor 601, memory 602, and communication component 603 are connected via a bus 604.

[0200] In a specific implementation, at least one processor 601 executes computer execution instructions stored in memory 602, causing at least one processor 601 to perform the above-described method.

[0201] The specific implementation process of processor 601 can be found in the above method embodiments, and its implementation principle and technical effect are similar. It will not be repeated here.

[0202] In the above embodiments, it should be understood that the processor can be a Central Processing Unit (CPU), or other general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), etc. The general-purpose processor can be a microprocessor or any conventional processor. The steps of the method disclosed in this invention can be directly implemented by a hardware processor, or implemented by a combination of hardware and software modules within the processor.

[0203] The memory may include random access memory (RAM) in high-speed memory, and may also include non-volatile memory (NVM), such as at least one disk storage device.

[0204] The bus can be an Industry Standard Architecture (ISA) bus, a Peripheral Component Interconnect (PCI) bus, or an Extended Industry Standard Architecture (EISA) bus, etc. Buses can be categorized as address buses, data buses, control buses, etc. For ease of illustration, the buses shown in the accompanying drawings are not limited to a single bus or a single type of bus.

[0205] This application also provides a computer program product, including a computer program that, when executed by a processor, implements the above-described method.

[0206] This application also provides a computer-readable storage medium storing computer-executable instructions, which, when executed by a processor, implement the above-described method.

[0207] The aforementioned readable storage medium can be implemented by any type of volatile or non-volatile storage device or a combination thereof, such as Static Random-Access Memory (SRAM), Electrically Erasable Programmable Read-Only Memory (EEPROM), Erasable Programmable Read-Only Memory (EPROM), Programmable Read-Only Memory (PROM), Read-Only Memory (ROM), magnetic storage, flash memory, magnetic disk, or optical disk. The readable storage medium can be any available medium accessible to a general-purpose or special-purpose computer.

[0208] An exemplary readable storage medium is coupled to a processor, enabling the processor to read information from and write information to the readable storage medium. Of course, the readable storage medium can also be a component of the processor. The processor and the readable storage medium can reside within an ASIC. Alternatively, the processor and the readable storage medium can exist as discrete components in a device.

[0209] The division of units is merely a logical functional division; in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the coupling or direct coupling or communication connection shown or discussed may be indirect coupling or communication connection through some interfaces, devices, or units, and may be electrical, mechanical, or other forms.

[0210] 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 network units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0211] In addition, 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.

[0212] If a function is implemented as a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of this invention, or the part that contributes to the prior art, or a 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 of the various embodiments of this invention. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, ROM, RAM, magnetic disks, or optical disks.

[0213] Those skilled in the art will understand that all or part of the steps of the above-described method embodiments can be implemented by hardware related to program instructions. The aforementioned program can be stored in a computer-readable storage medium. When executed, the program performs the steps of the above-described method embodiments; and the aforementioned storage medium includes various media capable of storing program code, such as ROM, RAM, magnetic disks, or optical disks.

[0214] Finally, it should be noted that other embodiments of the invention will readily occur to those skilled in the art upon consideration of the specification and practice of the invention disclosed herein. This invention is intended to cover any variations, uses, or adaptations of the invention that follow the general principles of the invention and include common knowledge or customary techniques in the art not disclosed herein, and is not limited to the precise structures described above and shown in the accompanying drawings, and various modifications and changes can be made without departing from its scope.

Claims

1. A method of controlling transformer energizing inrush, characterized by, The method is applied to the phase-controlled closing module in a transformer inrush current control system. The system also includes a circuit breaker and a transformer. The method includes: Obtain the tripping angle of the circuit breaker at the last tripping moment; Based on the opening angle and the environmental parameters inside the circuit breaker, the target closing angle of the circuit breaker is determined. Based on the target closing angle, the circuit breaker is controlled to close in order to suppress the inrush current of the transformer.

2. The method of claim 1, wherein, Based on the opening angle and the internal environmental parameters of the circuit breaker, the target closing angle of the circuit breaker is determined, including: Obtain the temperature and humidity values ​​inside the circuit breaker; Based on the opening angle, the residual magnetism generated after the circuit breaker opens is calculated; Based on the residual magnetism and the preset flux balance constraint equation, the initial closing angle of the circuit breaker is calculated. Based on the temperature and humidity values, the initial closing angle is corrected to obtain the target closing angle.

3. The method of claim 2, wherein, The step of correcting the initial closing angle based on the temperature and humidity values ​​to obtain the target closing angle includes: Based on the temperature value, the humidity value, and the initial closing angle, the closing angle correction term is obtained through a pre-trained closing angle correction model; The sum of the initial closing angle and the closing angle correction term is determined as the target closing angle; The closing angle correction model is obtained by training a neural network model based on the historical temperature value, historical humidity value, historical initial closing angle, and historical target closing angle of the circuit breaker.

4. The method according to any one of claims 1 to 3, characterized in that, The step of obtaining the tripping angle of the circuit breaker at the time of its last trip includes: Obtain the voltage and current signals of the circuit breaker at the time of its last trip; The tripping angle is calculated based on the current signal and the voltage signal.

5. The method of claim 4, wherein, The calculation of the tripping angle based on the current signal and the voltage signal includes: Based on the voltage signal and the current signal, the instantaneous phase of the voltage and the instantaneous phase of the current are calculated respectively using phase-locked loop technology; The phase difference between the instantaneous phase of the voltage and the instantaneous phase of the current when the current signal drops from a non-zero value to zero is determined as the tripping angle.

6. The method according to any one of claims 1 to 3, characterized in that, The method further includes: Based on the target closing angle, a closing operation command is generated; The closing operation command is sent to the circuit breaker through the closing command output channel of the phase-controlled closing module, so as to drive the circuit breaker to complete the closing operation at the target closing angle.

7. A control system for transformer energizing inrush, characterized by, include: The circuit breaker, the transformer, and the phase-controlled closing module, wherein the phase-controlled closing module is used to perform the method as described in any one of claims 1 to 6.

8. A control device for transformer energizing inrush, characterized by The device is applied to the phase-controlled closing module in a transformer inrush current control system. The system also includes a circuit breaker and a transformer. The device includes: The first processing module is used to obtain the opening angle of the circuit breaker at the last opening time; The second processing module is used to determine the target closing angle of the circuit breaker based on the opening angle and the environmental parameters inside the circuit breaker. The third processing module is used to control the circuit breaker to close based on the target closing angle, so as to suppress the inrush current of the transformer.

9. An electronic device, comprising: include: Memory, processor; The memory stores computer-executed instructions; The processor executes computer execution instructions stored in the memory, causing the processor to perform the method as described in any one of claims 1 to 6.

10. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores computer-executable instructions, which, when executed by a processor, are used to implement the method as described in any one of claims 1 to 6.

Images