An automatic switching impedance current limiting device

Abstract

The present invention provides an automatic switching impedance current limiting device, belonging to the technical field of switching impedance current limiting devices, including: a main control unit for judging whether switching or current limiting operations are required according to the data input by the acquisition unit and sending corresponding control instructions; an acquisition unit for real-time collecting the voltage, current, and frequency of the input power supply and transmitting this data to the main control unit as the criterion basis for switching and current limiting; a switching unit for quickly switching from the main power supply to the standby power supply under the control of the switching instruction of the main control unit to achieve seamless power supply switching; a current limiting unit for adjusting the equivalent impedance amount according to the current limiting instruction of the main control unit so as to limit the current output by the currently online power supply within a safe range; the main control unit includes: a prediction module for giving an early warning in advance to preheat the switching circuit or the impedance adjustment circuit; a judgment module for judging whether it is necessary to immediately start the switching or current limiting order.

Description

Technical Field

[0001] The present invention belongs to the technical field of switching impedance current limiting devices, and more particularly, relates to an automatic switching impedance current limiting device. Background Art

[0002] With the continuous improvement of the requirements for power supply reliability in modern society, the traditional passive power supply method can no longer meet the needs of some key application scenarios. In the fields of military communication, railway signal, medical surgery, etc., once the power supply system is interrupted or fails, it will cause significant economic losses and even potential safety hazards to life. Therefore, higher requirements are put forward for the reliability, stability and continuity of power supply.

[0003] Currently, common highly reliable power supply systems mainly adopt the hot standby method of main and standby power supplies. When the main power supply fails, it quickly switches to the standby power supply to ensure uninterrupted load power supply. This passive switching control technology requires manual monitoring of the main power supply status. Once a failure occurs, an immediate switching instruction is manually issued to switch to the standby power supply. This passive control has the following main problems:

[0004] 1. Reaction lag: Manual monitoring and operation responses are slow, and there is a time delay between the main power supply failure and the standby power supply switching, which may lead to a short interruption or even cause load damage.

[0005] 2. Operation uncertainty: It depends on manual experience judgment, is difficult to unify standards, and there is a possibility of mistakes and errors, which easily leads to incorrect switching. Summary of the Invention

[0006] In view of this, the present invention provides an automatic switching impedance current limiting device, which can solve the technical problems of the existing passive switching control, such as reaction lag and dependence on manual experience.

[0007] The present invention is implemented as follows:

[0008] The first aspect of the present invention provides an automatic switching impedance current limiting device, which includes: a main control unit, a collection unit, a switching unit, and a current limiting unit;

[0009] The main control unit is used to judge whether switching or current limiting operations are required according to the data input by the collection unit, and issue corresponding control instructions;

[0010] The collection unit is used to collect the voltage, current, and frequency of the input power supply in real time, and transmit this data to the main control unit as the basis for switching and current limiting criteria;

[0011] The switching unit is used to quickly switch from the main power supply to the standby power supply under the control of the switching instruction of the main control unit to achieve seamless power supply switching;

[0012] The current limiting unit is used to adjust the equivalent impedance according to the current limiting instruction of the main control unit, so as to limit the current output by the power supply currently online within a safe range;

[0013] Among them, the main control unit includes a prediction module and a judgment module. The prediction module is used to give a warning in advance with a preset warning time according to the parameters collected in real time, and preheat the switching circuit or impedance adjustment circuit; the judgment module is used to judge whether it is necessary to immediately start switching or current limiting according to the parameters collected in real time. When it is necessary to immediately start switching or current limiting, an switching instruction is immediately sent to the switching control unit or the impedance limiting instruction of the impedance amount is sent to the impedance control unit.

[0014] On the basis of the above technical solution, an automatic switching impedance current limiting device of the present invention can also be improved as follows:

[0015] Among them, the prediction module is used to execute the following steps:

[0016] S11. Receive the real-time data transmitted by the acquisition unit, including voltage, current, and frequency;

[0017] S12. Based on historical data, establish a time series model of voltage, current, and frequency;

[0018] S13. Input the real-time data into the time series model to predict the change trends of voltage, current, and frequency in a future period of time;

[0019] S14. According to the prediction trend, judge whether the preset switching threshold or current limiting threshold will be reached within the future prediction time;

[0020] S15. If it is predicted that the switching threshold or current limiting threshold will be reached, give a warning in advance with a preset warning time, and preheat the switching circuit or impedance adjustment circuit;

[0021] S16. Continuously update the real-time data, and repeat steps S11-S15 to dynamically adjust the prediction time and warning time.

[0022] Alternatively, the prediction module is used to execute the following steps:

[0023] Step 1. Receive the real-time data transmitted by the acquisition unit, including voltage, current, and frequency;

[0024] Step 2. Based on historical data, establish a time series model of voltage, current, and frequency;

[0025] Step 3. Initialize three grey wolves, which respectively represent voltage, current, and frequency, and randomly assign an initial position to each grey wolf, representing the current state of the corresponding index;

[0026] Step 4: Input the real-time data into the time series model to evaluate the fitness values of the three grey wolves, i.e., the deviation degrees of the current states of the three indicators from the expected target states;

[0027] Step 5: According to the grey wolf optimization algorithm, simulate the leader-follower behavior of the three grey wolves, adjust the positions of the three grey wolves to minimize the deviations of the three indicators, and the adjusted positions of the three grey wolves represent the predicted change trends of voltage, current, and frequency;

[0028] Step 6: According to the adjusted positions of the three grey wolves, judge whether the preset switching threshold or current limiting threshold will be reached within the future prediction time;

[0029] Step 7: If it is predicted that the switching threshold or current limiting threshold will be reached, give a warning with a preset warning time as the lead time, and preheat the switching circuit or impedance regulating circuit;

[0030] Step 8: Continuously update the real-time data, and repeat Steps 4 - 7 to dynamically adjust the prediction time and warning time.

[0031] Among them, the judgment module is used to execute the following steps:

[0032] S21: Receive the real-time data transmitted by the acquisition unit, including voltage, current, and frequency;

[0033] S22: Compare the real-time data with the preset switching threshold or current limiting threshold to judge whether the switching or current limiting condition has been reached;

[0034] S23: If the switching condition is reached, immediately send a switching instruction to the switching control unit;

[0035] S24: If the current limiting condition is reached, calculate the impedance amount to be adjusted, and immediately send the impedance amount current limiting instruction to the impedance control unit;

[0036] S25: Continuously monitor the real-time data, repeat Steps S21 - S24, and make switching or current limiting decisions in real time.

[0037] Furthermore, the time series model adopts the ARIMA model.

[0038] Furthermore, the specific steps of Step S14 include: setting the switching voltage threshold as [0.9V n , 1.1V n , where V n is the rated voltage; setting the switching frequency threshold as [0.95f n , 1.05f n , where f n is the rated frequency; setting the current limiting current threshold as 1.2I n, where I n is the rated current; compare the predicted future voltage and frequency sequences with the corresponding switching threshold intervals, and compare the real-time current value with the current limiting threshold. If there is a situation where the threshold is exceeded within the prediction time, it is determined that the switching or current limiting threshold will be reached.

[0039] Further, the specific steps of step S15 include: setting the warning time to T seconds. When it is predicted that the switching threshold will be reached after T seconds, the prediction module of the main control unit sends a preheating signal to the switching control unit. After receiving this signal, the switching control unit charges the backup power supply, detects the status of the backup power supply, and preheats the switching circuit to make the switching circuit enter the ready state; when it is predicted that the current limiting threshold will be reached after T seconds, the prediction module of the main control unit sends a preheating signal to the impedance control unit. The impedance control unit calculates the impedance amount to be adjusted according to this signal and preheats the impedance adjustment circuit.

[0040] Among them, the switching circuit includes a main power supply switching module, a standby power supply switching module, a switching control module, and a parallel inverter module. Both the main power supply switching module and the standby power supply switching module include a static switch and a protection unit. The static switch usually uses a thyristor or an IGBT; the switching control module consists of a controller, a drive circuit, and a timing logic circuit, and coordinates the actions of the main and standby power supply switching modules after receiving the switching instruction; the parallel inverter module includes two parallel inverter circuits and realizes seamless switching based on the orthogonal vector inversion control algorithm; the preheating of the switching circuit refers to: powering on the parallel inverter module and the switching control module for 2 to 3 times the preset warning time.

[0041] Among them, the impedance adjustment circuit includes a controllable impedance unit and an impedance control module. The controllable impedance unit is composed of multiple controllable resistors or reactors connected in parallel and can dynamically adjust the equivalent impedance; the impedance control module includes a controller and an encoder. The controller calculates the target impedance R' according to the formula, and the encoder encodes R' into a switch control code. The controllable impedance unit adjusts the total equivalent impedance to R' according to the control code; the preheating of the impedance adjustment circuit refers to: pre-encoding the impedance control module, that is, the controller calculates the target impedance R' according to the formula, and the encoder encodes R' into a switch control code and stores it.

[0042] The switching control unit or the impedance control unit sends a preheating signal to enable the corresponding execution circuit to make preparations in advance.

[0043] After receiving the preheating signal from the prediction module, the switching link immediately charges the backup power supply and detects its status, and at the same time preheats the parallel inverter and the switching control circuit. Once the switching instruction is received, the switching action can be completed within a few milliseconds to achieve seamless switching of the main and standby power supplies.

[0044] After receiving the preheating signal from the prediction module, the current limiting section calculates the target equivalent impedance value to be adjusted and performs preheating encoding on the switching state of the controllable impedance unit. Once the current limiting instruction is received, the impedance adjustment can be completed within a few microseconds to limit the current within the safety threshold.

[0045] Further, the specific steps of step S23 include: when the judgment module finds that the switching condition has been reached, it immediately sends a switching instruction to the switching control unit. The switching control unit detects the state of the standby power supply and sends a switching signal, controls the switching circuit to separate the load from the main power supply and connect it to the standby power supply, controls the parallel inverters of the main power supply and the standby power supply to achieve seamless switching, and finally shuts down the main power supply.

[0046] Further, the specific steps of step S24 include: when the judgment module finds that the current limiting condition has been reached, it calculates the equivalent impedance amount to be adjusted according to the real-time current value, and immediately sends a corresponding impedance amount current limiting instruction to the impedance control unit. The impedance control unit calculates the target impedance R' according to the current value in the instruction and controls the controllable impedance unit to adjust the total equivalent impedance to R', thereby limiting the current within the safe range.

[0047] Compared with the prior art, the beneficial effects of an automatic switching impedance current limiting device provided by the present invention are:

[0048] 1. Improve the switching response speed

[0049] The traditional passive switching control method relies on manual monitoring and operation, and there is a problem of reaction lag. The present invention adopts an active prediction method, which can accurately predict the switching conditions to occur, make all preparations in advance, and immediately send a switching instruction once the switching threshold is reached. The switching circuit can complete the switching action within a few milliseconds. The response speed of this active switching control far exceeds manual operation, effectively avoiding power interruption and ensuring continuous and reliable power supply for critical loads.

[0050] 2. Improve the switching reliability

[0051] The traditional switching method completely relies on manual experience judgment, and there are risks of operation uncertainty and mistakes. The present invention adopts an intelligent judgment module, compares the prediction result with the set switching threshold conditions, and automatically decides whether to switch through strict mathematical criteria, avoiding the uncertainty of manual operation and improving the reliability of switching control. At the same time, through time series analysis, it can fully consider the volatility and suddenness of power supply data, improving the response adaptability to complex fault scenarios.

[0052] 3. Eliminate the waste of current limiting energy consumption

[0053] Existing current-limiting control technologies usually adopt fixed current-limiting components, permanently connecting a resistor or an inductor in series in the circuit. Although this approach can prevent overload, it will also bring additional voltage drops and energy losses during normal operation, affecting the overall power supply efficiency. In contrast, the present invention adopts a current-limiting control method of dynamic impedance regulation, which only adjusts the equivalent internal resistance when the current reaches the current-limiting threshold, limits the current within a safe range, and does not generate additional losses under normal working conditions, fundamentally eliminating the energy waste problem of fixed current-limiting.

[0054] 4. Improve output performance

[0055] Fixed current-limiting components not only cause energy losses but also permanently limit the maximum output capacity of the power supply. The dynamic current-limiting technology of the present invention maintains the minimum equivalent internal resistance under normal working conditions, enabling the power supply to fully exert its rated output capacity without any artificial restrictions. At the same time, the dynamic adjustment of the internal resistance can promptly suppress the instantaneous impact of the current and effectively avoid the transient overload of the current, thereby further improving the output performance and reliability of the power supply.

[0056] In summary, the solution of the present invention solves the technical problems of the existing passive switching control, such as reaction lag and dependence on manual experience. Brief description of the drawings

[0057] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following will briefly introduce the drawings required for the description of the embodiments of the present invention. Obviously, the following drawings are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0058] Figure 1 It is a schematic diagram of the composition of an automatic switching impedance current-limiting device provided by the present invention;

[0059] Figure 2 It is a flowchart of the steps executed by the prediction module;

[0060] Figure 3 It is a flowchart of the steps executed by the judgment module;

[0061] Figure 4 It is a schematic diagram of the composition of the switching circuit;

[0062] Figure 5 It is a schematic diagram of the composition of the impedance adjustment circuit. Detailed implementation manners

[0063] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the drawings in the embodiments of the present invention.

[0064] As shown Figure 1 in the figure, it is a schematic diagram of the composition of an automatic switching impedance current limiting device provided by the present invention, including: a main control unit, a collection unit, a switching unit, and a current limiting unit;

[0065] The main control unit is used to judge whether switching or current limiting operations are required according to the data input by the collection unit, and issue corresponding control instructions;

[0066] The collection unit is used to collect the voltage, current, and frequency of the input power supply in real time, and transmit this data to the main control unit as the basis for judging switching and current limiting;

[0067] The switching unit is used to quickly switch from the main power supply to the standby power supply under the control of the switching instruction of the main control unit to achieve seamless power supply switching;

[0068] The current limiting unit is used to adjust the equivalent impedance according to the current limiting instruction of the main control unit, so as to limit the current output by the currently online power supply within a safe range;

[0069] Among them, the main control unit includes a prediction module and a judgment module. The prediction module is used to give an early warning based on the real-time collected parameters with a preset early warning time as an advance, and preheat the switching circuit or impedance adjustment circuit; the judgment module is used to judge whether it is necessary to immediately start switching or current limiting according to the real-time collected parameters. When it is necessary to immediately start switching or current limiting, an switching instruction is immediately sent to the switching control unit or an impedance amount current limiting instruction is sent to the impedance control unit.

[0070] Among them, the prediction module is used to execute the following steps:

[0071] S11. Receive the real-time data transmitted by the collection unit, including voltage, current, and frequency;

[0072] S12. Based on historical data, establish a time series model of voltage, current, and frequency;

[0073] S13. Input the real-time data into the time series model to predict the change trend of voltage, current, and frequency in the next period of time;

[0074] S14. According to the prediction trend, judge whether the preset switching threshold or current limiting threshold will be reached within the future prediction time;

[0075] S15. If it is predicted that the switching threshold or current limiting threshold will be reached, give an early warning with a preset early warning time as an advance, and preheat the switching circuit or impedance adjustment circuit;

[0076] S16. Continuously update the real-time data, and repeat steps S11-S15 to dynamically adjust the prediction time and early warning time.

[0077] The judgment module is used to perform the following steps:

[0078] S21. Receive the real-time data transmitted by the acquisition unit, including voltage, current, and frequency;

[0079] S22. Compare the real-time data with the preset switching threshold or current limiting threshold to determine whether the switching or current limiting condition has been reached;

[0080] S23. If the switching condition is reached, immediately send a switching instruction to the switching control unit;

[0081] S24. If the current limiting condition is reached, calculate the impedance amount to be adjusted, and immediately send the impedance amount current limiting instruction to the impedance control unit;

[0082] S25. Continuously monitor the real-time data, repeat steps S21 - S24, and make switching or current limiting decisions in real time.

[0083] The specific implementation manners of the above steps are described in detail below:

[0084] The specific implementation manner of step S11 is: The prediction module of the main control unit receives the real-time data transmitted by the acquisition unit, including voltage, current, and frequency. These data are important indicators of the real-time operation state of the system, directly reflecting the actual situation of power input and output, and are the basic data for subsequent prediction and judgment.

[0085] The specific implementation manner of step S12 is: Based on historical data, establish a time series model of voltage, current, and frequency. The time series model is a statistical model for predicting future data. It uses the internal laws and trends existing in historical data and combines appropriate mathematical methods to predict future data. In the present invention, time series prediction models such as autoregressive moving average model (ARMA), autoregressive integrated moving average model (ARIMA), and exponential smoothing model can be used. These models need to be trained based on a sufficiently long historical data for model training and parameter estimation to improve the prediction accuracy. For example, for the ARIMA model, it is necessary to determine the autoregressive order p, the differencing order d, and the moving average order q, and estimate the corresponding parameters according to historical data. Selecting an appropriate time series model and parameter estimation method is crucial for improving the prediction accuracy.

[0086] The specific implementation manner of step S13 is: Input the real-time data into the time series model to predict the change trends of voltage, current, and frequency in the future for a period of time. Using the established time series model, input the currently collected real-time data, and the model will calculate the change trends of voltage, current, and frequency in the future for a period of time according to the internal mathematical formulas and parameters. For example, for the ARIMA(p, d, q) model, the predicted value can be expressed as:

[0087] y t = c + φ1 * y t-1 + … + φ p * y t-p - θ1 * e t-1 - … - θ q * e t-q + e t

[0088] where y t represents the predicted value of time t, c is a constant term, φ i and θ j are the coefficients of autoregression and moving average respectively, e t is the residual term at time t, where i ∈ [1, p], j ∈ [1, q]. By substituting real-time data into this formula, a sequence of predicted values for a future period of time can be obtained, thereby determining the change trend.

[0089] The specific implementation of step S14 is as follows: According to the predicted trend, it is judged whether the preset switching threshold or current limiting threshold will be reached within the future predicted time. The switching threshold and current limiting threshold are safety critical values set by the system for judging whether switching or current limiting operations need to be initiated. For example, the switching threshold can be set to 10% of the rated voltage deviation, that is, 0.9 times or 1.1 times the rated voltage; the current limiting threshold can be set to 120% of the rated current. By comparing the predicted voltage and current change trends within a future period of time with these thresholds, it is judged whether the thresholds will be reached within the predicted time. If the predicted trend shows that the threshold will be reached, it is necessary to make preparations in advance to avoid the system being unable to respond in a timely manner in case of emergencies.

[0090] The specific implementation of step S15 is as follows: If it is predicted that the switching threshold or current limiting threshold will be reached, an early warning is given with a preset early warning time as an advance, and the switching circuit or impedance adjustment circuit is preheated. The early warning time is a time parameter set by the system for making corresponding preparations in advance. For example, the early warning time can be set to 5 seconds. When it is predicted that the switching threshold will be reached in 5 seconds, the system will send an early warning signal 5 seconds in advance and preheat the switching circuit to make it enter the working ready state. Similarly, when it is predicted that the current limiting threshold will be reached in 5 seconds, the system will send an early warning signal 5 seconds in advance and preheat the impedance adjustment circuit to prepare for the upcoming impedance adjustment. The purpose of preheating the circuit is to shorten the response time of subsequent actual switching or current limiting operations and improve the reaction speed of the system.

[0091] The specific implementation of step S16 is as follows: Continuously update the real-time data, repeat steps S11 - S15, and dynamically adjust the prediction time and warning time. Since the power system is in a dynamic state, to ensure the real-time nature of prediction and decision-making, it is necessary to continuously obtain the latest real-time data and repeat the above steps for rolling prediction and decision-making. At the same time, according to the actual situation, the lengths of the prediction time and warning time can be dynamically adjusted. For example, when the system state tends to be stable, the prediction time can be appropriately extended to give an early warning earlier; when the system state fluctuates violently, the prediction time can be shortened to react in a timely manner. Dynamically adjusting the prediction time and warning time helps to improve the accuracy of prediction and the timeliness of decision-making.

[0092] The specific implementation of step S21 is as follows: The judgment module of the main control unit receives the voltage, current, and frequency data transmitted in real time by the acquisition unit. These data reflect the actual working state of the current power supply and are the basis for judging whether immediate switching or current limiting operations need to be started. To ensure the accuracy and real-time nature of the data, the acquisition unit should use high-precision, high-sampling-rate sensors and data acquisition circuits, and preprocess the original data through anti-interference and digital filtering means to exclude the influence of noise and interference. At the same time, a high-speed data transmission interface, such as optical fiber communication or Ethernet communication, should be used between the acquisition unit and the main control unit to ensure that the data can be transmitted to the judgment module in real time and accurately.

[0093] The specific implementation of step S22 is to compare the received real-time data with the preset switching threshold or current limiting threshold to determine whether the switching or current limiting conditions have been reached. Among them, the reference values for setting the switching threshold and current limiting threshold are as follows: The switching voltage threshold is [0.9V n , 1.1V n , where V n is the rated voltage value; the switching frequency threshold is [0.95f n , 1.05f n , where f n is the rated frequency value; the current limiting current threshold is 1.2I n , where I n is the rated current value. These thresholds can be appropriately adjusted according to the actual application scenario and safety requirements. The judgment module compares the real-time voltage and frequency values with the corresponding switching threshold intervals. If the real-time value exceeds the threshold interval, it is determined that the switching condition has been reached; the real-time current value is compared with the current limiting current threshold. If the real-time value exceeds the threshold, it is determined that the current limiting condition has been reached. This step uses a simple comparison algorithm to quickly determine whether immediate switching or current limiting operations need to be started by comparing the size relationship between the real-time data and the preset threshold.

[0094] The specific implementation of step S23 is as follows: If the judgment module detects that the switching condition has been met, it immediately sends a switching instruction to the switching control unit, instructing it to start the switching procedure to quickly switch from the main power supply to the backup power supply, achieving seamless power supply switching. After receiving the switching instruction, the switching control unit will perform the following operations: First, it will detect the status of the backup power supply to ensure that it is in a normal operating state; Second, it will send a switching signal to control the switching circuit to disconnect the load from the main power supply and connect it to the backup power supply; At the same time, it will control the parallel inverters of the main power supply and the backup power supply to achieve seamless switching, avoiding interruption of the load power supply; Finally, it will turn off the main power supply to completely isolate the faulty power supply. The entire switching process needs to be completed in an extremely short time to ensure uninterrupted power supply for critical loads. In this step, the switching control unit can adopt a fast switching algorithm to optimize the switching timing and shorten the switching time.

[0095] The specific implementation of step S24 is as follows: If the judgment module detects that the current limiting condition has been met, it will calculate the equivalent impedance amount to be adjusted based on the real-time current value, and immediately send a corresponding impedance amount current limiting instruction to the impedance control unit. After receiving the current limiting instruction, the impedance control unit will adjust the equivalent impedance of the current limiting circuit to control the power supply output current within a safe range. The specific calculation process is as follows: Let the internal resistance of the power supply be R, and the load impedance be R L , according to Ohm's law, under the given voltage V, the current To make the current I not exceed the current limiting threshold I max Adjust the equivalent internal resistance R', so that The control unit calculates the minimum equivalent internal resistance R' to be increased according to this formula, and controls the current limiting circuit to adjust to this impedance value, thereby limiting the current to I max This step utilizes Ohm's law and the principle of circuit equivalent impedance. By adjusting the equivalent internal resistance, it realizes the active limitation of the current and avoids potential safety hazards caused by current overload.

[0096] The specific implementation of step S25 is as follows: Continuously monitor the real-time data transmitted by the acquisition unit, repeatedly execute steps S21 - S24, and make switching or current-limiting decisions in real time. Since the operating conditions of the system are constantly changing, to ensure the real-time and accuracy of control decisions, it is necessary to continuously monitor and judge the latest acquired data. Whenever new real-time data is received, the judgment module will re-execute the above steps, compare the new data with the threshold, and decide whether to issue a switching instruction or a current-limiting instruction according to the comparison result. At the same time, the judgment module also needs to dynamically adjust the settings of the switching threshold and the current-limiting threshold according to the change trend of the data. For example, when the load surges, the current-limiting current threshold can be appropriately increased to allow a larger current output; when power supply failures occur frequently, the switching voltage / frequency threshold interval can be appropriately reduced to start the switching procedure in advance. This dynamic threshold adjustment strategy can make the control decision adapt to the actual operating conditions and improve the stability and reliability of the system.

[0097] Among them, the switching circuit is the key circuit to realize the rapid switching of the main and backup power supplies. It consists of a main power supply switching module, a backup power supply switching module, a switching control module, and a parallel inverter module.

[0098] The main power supply switching module includes a main power supply static switch and a main power supply protection unit. The static switch usually uses semiconductor devices such as thyristors or IGBTs. It conducts during normal operation to connect the main power supply to the load; once it receives the switching instruction from the switching control module, the static switch will quickly turn off, cutting off the connection between the main power supply and the load. The main power supply protection unit can cut off the main power supply in a timely manner in case of abnormalities in the main power supply to prevent the spread of faults.

[0099] The structure of the backup power supply switching module is similar to that of the main power supply switching module, and also includes a backup power supply static switch and a backup power supply protection unit. The difference is that the backup power supply switching module is in the off state under normal circumstances. Once it receives the switching instruction, the static switch will quickly conduct to connect the backup power supply to the load.

[0100] The switching control module is the control center of the entire switching circuit. It receives the switching instruction issued by the main control unit and coordinates the actions of the main and backup power supply switching modules according to the preset switching timing to achieve seamless switching. This module usually consists of a controller, a drive circuit, and a timing logic circuit. The controller receives and parses the switching instruction, the timing logic circuit generates control signals according to the switching timing, and the drive circuit controls the static switch to conduct or turn off according to the control signals.

[0101] The parallel inverter module is the key to achieving smooth switching between the main and backup power supplies. It consists of two parallel inverter circuits, one connected to the main power supply and the other to the backup power supply. The two inverters will operate alternately during the switching process to ensure the continuity of the load voltage. When the main power supply fails, the backup power supply inverter immediately takes over to supply power to the load until the backup power supply fully takes over the power supply task. The core of this module is the inverter control algorithm based on orthogonal vectors, which can precisely control the phase and amplitude of the inverter output voltage, making the output voltages of the main and backup power supply inverters phase-synchronized.

[0102] After receiving the switching instruction, each module of the switching circuit will act in coordination: the main power supply switching module quickly cuts off the main power supply, while the backup power supply switching module connects the backup power supply; the switching control module controls the parallel inverter module to start the switching program, and the output voltage of the parallel inverter transitions smoothly to achieve seamless switching. The entire process is completed within a few milliseconds to ensure uninterrupted power supply to the load.

[0103] The impedance regulation circuit is the actuator for current limiting control. It mainly consists of a controllable impedance unit and an impedance control module. The controllable impedance unit is a circuit that can dynamically adjust the equivalent impedance, usually composed of several controllable resistors or controllable reactors in parallel. Each controllable resistor (reactor) is composed of a fixed resistor (reactor) in parallel with a semiconductor switch. By turning the switch on or off, the total conduction state of the parallel branch can be controlled, thereby adjusting the equivalent impedance value.

[0104] The impedance control module is responsible for calculating the amount of impedance to be adjusted according to the current limiting instruction issued by the main control unit and coordinating the switch states of the controllable resistors (reactors) in the controllable impedance unit. This module mainly consists of a controller and an encoder. The controller receives the current limiting instruction and calculates the target impedance R' according to the above-mentioned The encoder encodes R' into the corresponding switch control code and sends it to the controllable impedance unit to make the conduction state of its parallel branch meet the target impedance requirement.

[0105] After receiving the current limiting instruction, the impedance control module first calculates the target equivalent impedance R' according to the current value in the instruction, then the encoder converts R' into a switch control code, and the controllable impedance unit adjusts the conduction state of the parallel branch according to the control code to adjust the total equivalent impedance to R'. Since the response speed of the controllable impedance unit is extremely fast, the impedance switching can be completed in just a few microseconds. The entire current limiting process can be started at the moment when the current suddenly increases to timely suppress the generation of overload current. By dynamically adjusting the equivalent internal resistance, the impedance regulation circuit limits the current within the safety threshold, effectively preventing the occurrence of overload phenomena.

[0106] The innovation of the switching circuit and the impedance regulation circuit lies in their ability to complete switching and current-limiting regulation in an extremely short time, with a reaction speed that is difficult for traditional circuits to match. Their fast response ability benefits from the use of semiconductor static switches, high-speed control algorithms, and advanced power electronics technologies. At the same time, the actions of the two circuits are uniformly commanded by the main control unit, realizing the automation of switching and current-limiting control, avoiding the inefficiency and errors of manual operation, and improving the reliability and intelligence level of the power supply system.

[0107] The following combines specific embodiments to describe in detail the principle, structure, and working process of the active switching current-limiting control system of the present invention.

[0108] This embodiment adopts a three-phase four-wire output design, with a rated output power of 50 kVA, an input voltage range of 380V ± 20%, a frequency of 50 Hz, an output voltage of 380V, and a frequency of 50 Hz. The control system adopts a three-layer hierarchical architecture, including an intelligent judgment layer, a coordination control layer, and an execution layer. The system hardware consists of a main circuit module, a control circuit module, and an auxiliary circuit module.

[0109] 1. Main circuit module

[0110] The main circuit module includes four sub-modules: a main power supply, a backup power supply, a parallel inverter, and a dynamic current-limiting circuit.

[0111] (1) Main power supply and backup power supply

[0112] Both the main power supply and the backup power supply adopt a three-level non-isolated buck-type full-bridge inverter topology. The rectifier stage uses a 12-pulse redundant parallel unified power flow controller (UPFC), with a DC side voltage of 640V and an inductance value of 2 mH. The full-bridge inverter stage is composed of 4 IGBT module strings in parallel, and each IGBT module is rated at 1200V / 200A. The module-level control chip uses an STM32-type DSP..

[0113] The output terminals of the two power supply units are connected through a three-phase parallel inverter circuit, and seamless switching can be realized during parallel connection, and the normal power supply of the system is not affected by any power supply failure.

[0114] (2) Parallel inverter circuit

[0115] A three-phase four-arm voltage-source inverter circuit is adopted, and the IGBT module is of the FF300R17ME4 type, with 4 IGBT modules (1200V / 300A) in parallel for each arm. The control chip of the parallel inverter circuit uses an XC3S1000-type FPGA, and the control algorithm uses SPWM phase-shift modulation, so as to realize the phase synchronization of the output voltages of the two power supplies. The switching control module is responsible for the execution of the switching action.

[0116] During the seamless switching process, the parallel inverters adopt a dual-channel control link and an inverter hardware redundancy design. The control link includes two control loops: a current loop and a voltage loop. The phase shift logic in the composite modulation uses the feedforward signal of the voltage loop to control the phase of the inverter, and the phases of the main power supply and the backup power supply do not affect each other. When the switching controller detects that the switching condition is met, one backup power inverter will output at a voltage phase slightly lower than that of the other working power supply, and this automatically forms a smooth switching between the two currents through the feedback control mechanism of the current loop. If the two phases remain consistent, the current switching will be completed smoothly without instantaneous impact. For instantaneous resistance, inductive resistance loads, and nonlinear loads, this switching process will be completed within a few milliseconds.

[0117] (3) Dynamic current limiting circuit

[0118] The dynamic current limiting circuit adopts a series current limiting topology, which is composed of 8 impedance branches in parallel. The impedance value of each branch ranges from 0.05Ω to 12.8Ω, and the theoretical equivalent impedance can be dynamically adjusted within the range of 0.05Ω - 0.39Ω. The impedance unit uses STM32-bit series metal oxide field effect transistors with a rated continuous working current of 100A. In the normal working state, each branch remains fully conducting, and the equivalent internal resistance is close to zero. Once an overload occurs and current limiting is urgently needed, the current limiting controller controls each branch to open or close through binary weighted coding, thereby adjusting the total equivalent impedance within microseconds and limiting the load current within the rated range. This dynamic current limiting method greatly improves the overload resistance and protection accuracy of the system.

[0119] The control chip of the dynamic current limiting module uses the XC7K70T type FPGA of XILINX Company, which is connected to the main controller through a high-speed peripheral interface to achieve rapid state adjustment. The current limiting control logic quickly determines the target current limiting equivalent impedance through mathematical calculations based on the set current limiting threshold and the load current feedback value, and specifically controls the conduction state of each branch MOSFET.

[0120] 2. Control circuit module

[0121] The control circuit module adopts a hierarchical architecture design, including three levels: an intelligent judgment layer, a coordination control layer, and an execution layer.

[0122] (1) Intelligent judgment layer

[0123] The core control chip of the intelligent judgment layer is an Intel dual-core processor with a main frequency of 1.86GHz. This layer is mainly responsible for establishing an ARIMA time series model, and based on methods of mathematical statistics and theoretical derivation, deeply mining and analyzing and predicting power grid data.

[0124] Time series analysis includes model identification processes such as autocorrelation analysis, partial autocorrelation analysis, and white noise test. The model orders p, d, q are determined by the BOX-JENKINS method, and the model parameters are estimated by the least squares method. On this basis, the ARIMA(p, d, q) model is used to perform short-term prediction on key data such as voltage, current, and frequency.

[0125] The intelligent judgment layer collects grid data every 500 ms and analyzes and judges the prediction curve according to the set switching threshold conditions (such as voltage deviating from ±15% up and down, frequency deviating from ±3 Hz, current exceeding 120% of the rated value, etc.). Once it is found that the switching or current limiting conditions will be reached, a preheating signal is immediately sent to the coordinated control layer.

[0126] (2) Coordinated control layer

[0127] The core controller of the coordinated control layer is an STM32 series chip, which integrates an ARM dual-core Cortex-A9 processor and programmable logic resources. This layer receives the preheating instructions from the intelligent judgment layer and coordinates the preparation work of each execution layer according to different situations of switching or current limiting.

[0128] When preparing for switching, the coordinated control layer needs to start the charging process of the standby power supply and detect its working status. At the same time, a preheating instruction is sent to the parallel inverter and the switching controller to make them enter the standby state.

[0129] When preparing for current limiting, the coordinated control layer needs to calculate the target current limiting equivalent impedance according to the prediction value and send the corresponding control instructions to the current limiting controller in advance.

[0130] Once the intelligent judgment layer issues a switching or current limiting execution instruction, the coordinated control layer immediately issues an instruction to the corresponding execution layer to start the subsequent actions.

[0131] (3) Execution layer

[0132] The execution layer includes a power supply preheating module, an inverter control module, a switching execution module, and a current limiting execution module.

[0133] The power supply preheating module controls the rectifier stage, inverter stage, and filter circuit of the standby power supply to start in sequence, and checks the voltage, current, and temperature parameters to ensure that it is in a normal standby state.

[0134] The inverter control module controls the IGBT module of the parallel inverter circuit to conduct, so that it outputs synchronously according to the required phase, and monitors the current loop in real time to prepare for seamless switching.

[0135] The switching execution module controls the mechanical or static switch elements in the switching control circuit to complete the switching-in of the main and standby power supplies. The parallel inverter seamless switching algorithm is adopted during the switching process to ensure smooth and impact-free switching.

[0136] The current limiting execution module controls the on-circuit and off-circuit states of the MOSFET in the dynamic current limiting module, thereby realizing rapid adjustment of the impedance equivalent value and limiting the current within the rated range.

[0137] The auxiliary circuit module includes sub-modules such as DC filtering and bus energy storage, intermediate transformer, wireless communication module, intelligent diagnosis module, and environmental monitoring sensor.

[0138] These modules play an auxiliary supporting role, providing the required power, communication and monitoring services for the main circuit and control circuit modules.

[0139] 3. System working process

[0140] After the system is powered on and started, it first enters normal power supply operation. The main power supply unit is in operation and maintains full rated power, while the backup power supply unit is idle and on standby. The parallel inverter circuit synchronizes the main power supply voltage phase output, the switching control circuit is in the main power supply connection state, and the dynamic current limiting circuit maintains a fully conductive state with an equivalent internal resistance of zero.

[0141] The voltage, current, and environmental monitoring sensors receive relevant data and pass it to the control layer for processing via the A / D conversion module. Simultaneously, the system also receives relevant status data from the external communication network.

[0142] At the intelligent judgment layer, a time series forecast is established based on the ARIMA model to obtain the changing trends of voltage, current, and frequency over a period of time. Based on the set threshold conditions, it is determined whether the system will switch on or off or current limit.

[0143] If the prediction result is normal, the normal power supply operation state will be maintained.

[0144] If the prediction result indicates that a switching situation will occur, such as voltage or frequency deviation from the threshold, power failure, etc., the intelligent judgment layer immediately sends a switching preheating signal to the coordination control layer. After receiving the preheating signal, the coordination control layer starts the following procedures:

[0145] (1) Command the backup power supply unit to preheat and charge and stand by; (2) Command the parallel inverter circuit to enter the standby state and output a voltage slightly lower than the main voltage phase through the control algorithm; (3) Command the switching control circuit to prepare for switching operation.

[0146] Once the intelligent judgment layer confirms that the switching conditions have been met, it immediately issues a switching instruction. Upon receiving the instruction, the coordination control layer immediately controls the switching control circuit to disconnect the primary power supply and switch to the backup circuit. Because the backup power inverter voltage phase is slightly offset in advance, the primary and backup currents are automatically and smoothly switched seamlessly. The entire switching process is completed within 5 milliseconds, without affecting the continuity of load power supply.

[0147] If the prediction result determines that current limiting will occur, such as when the load current is about to exceed the rated threshold, the intelligent judgment layer sends a current limiting preheating signal to the coordinated control layer. After receiving the preheating signal, the coordinated control layer calculates the target current limiting equivalent impedance through the dynamic impedance regulation algorithm according to the predicted current value, and issues a control code to the current limiting execution module in advance.

[0148] Once the intelligent judgment layer confirms that the current limiting condition has been reached, it immediately issues a current limiting execution instruction. The current limiting execution module immediately controls the open or conduction state of each MOSFET in the current limiting circuit according to the pre-coding, and instantaneously adjusts the equivalent impedance to the preset value. The whole process is completed within 30 microseconds, effectively limiting the abnormal current within a safe range.

[0149] The switching and current limiting operations can also make autonomous decisions on whether to continue according to the feedback of the intelligent diagnosis module. If the voltage and frequency return to normal, or the fault is eliminated, the normal power supply state will be automatically restored.

[0150] The above is the description of the embodiment of the active switching current limiting control system of the present invention. By organically integrating the three links of prediction, switching and current limiting, after model identification, the judgment layer conducts multi-dimensional time series prediction and analysis on key data such as input voltage, current, and frequency based on the ARIMA(p, d, q) model, and predicts the data trend in the next period of time. Among them, p is the autoregressive order, d is the difference order, and q is the moving average order. In this embodiment, p = 2, d = 1, q = 1, that is, the ARIMA(2, 1, 1) model is adopted.

[0151] The calculation formula of the ARIMA model is:

[0152]

[0153] Among them, X(t) is the predicted value at time t, is the autoregressive coefficient, ε(t) is the white noise sequence, and θ1 is the moving average coefficient.

[0154] The model parameters are determined by methods such as the least squares method or maximum likelihood estimation. The judgment layer collects data every 5ms and performs real-time rolling prediction with a 30ms unit time window, and the prediction range is 1 second.

[0155] Based on the prediction result, the judgment layer compares the prediction curve with the set switching threshold / current limiting threshold. If there is data that will break through the threshold within 1 second, it sends a preheating signal to the next layer and gives the breakthrough time window.

[0156] (2) Coordinated control layer

[0157] The core of the coordination control layer is an STM32 dual-core floating-point DSP with a main frequency of 300 MHz, integrating numerous communication and control peripherals. The main function of this layer is to coordinate the main and standby power supplies and other subsystems to prepare for switching or current limiting according to the preheating instructions from the upper layer.

[0158] After receiving the preheating signal from the upper layer, the coordination control layer first determines whether it is switching preheating. If so, it immediately issues the main power parallel connection instruction and the standby power parallel connection instruction to prepare for subsequent switching. At the same time, it also needs to control the standby power circuit to start charging the electrolytic capacitor and the preheating switching control circuit.

[0159] If it is current limiting preheating, the coordination control layer calculates the target current limiting impedance according to the preheating moment and sends it to the current limiting control unit through the optical fiber channel. After receiving the instruction, the control unit will calculate the required conduction states of each branch and pre-encode and latch them to make full preparations for subsequent rapid response.

[0160] (3) Execution layer

[0161] The execution layer mainly includes two parts: the power execution unit and the current limiting execution unit. The power execution unit consists of two power module units, the main power supply and the standby power supply. Each module unit has an STM32-type DSP chip built-in, which is responsible for the internal power module control.

[0162] This layer is connected to the upper layer through the optical fiber / CAN bus and receives the switching control command or current limiting control command from the upper layer. For example, when receiving the switching control command, the execution layer immediately makes the standby power supply output voltage with a slightly lower phase, and the output currents of the main power supply and the standby power supply are smoothly switched through the feedback control of the current loop. The entire switching process is completed within a few milliseconds.

[0163] The current limiting execution unit is responsible for the control of the dynamic current limiting circuit. Once it receives the current limiting instruction, it controls the on states of the MOSFETs of each branch through a parallel high-speed encoder / decoder to make the total current limiting resistance reach the target value and limit the current within the safe range within a few microseconds.

[0164] The execution layer uses a dedicated power electronics chipset of FPGAs and DSPs to ensure the timeliness and efficiency of control response.

[0165] 3. Auxiliary circuit module

[0166] The auxiliary circuit module provides auxiliary support for the main control module and the power module, mainly including a power filter circuit, a cooling system, a communication interface circuit, a monitoring circuit, and a housing, etc.

[0167] (1) Power filter circuit

[0168] The power supply filtering circuit includes a rectifier circuit and a main filtering circuit. The rectifier circuit is a 12-pulse redundant parallel passive pick-up circuit, which can effectively suppress harmonic current and improve rectification efficiency. The main filtering circuit adopts an LC filter to further filter out high-frequency components and ensure the purity of the DC bus voltage.

[0169] (2) Cooling system

[0170] The cooling system adopts an air-cooled thermal management design and consists of a heat exchanger, a fan, and a temperature control circuit. The heat exchanger is set at the power module and power electronic devices, and uses an aluminum alloy heat conduction plate to contact the junction temperature element to transfer heat to the heat sink fins. The system is equipped with dual-redundant fans, and the operation of the fans is controlled by a fan drive chip. The fan drive chip will also automatically adjust the fan speed according to the junction temperature signal detected by the temperature sensor to save energy to the greatest extent.

[0171] (3) Communication interface circuit

[0172] The communication interface circuit provides two communication methods: wired and wireless. Wired communication uses standard CAN bus and RS485 bus interfaces, which can be connected to a host computer or other external devices to achieve remote monitoring and control. Wireless communication uses a ZigBee wireless communication module, which operates in the 2.4GHz ISM band, with a data transmission rate of up to 250Kbps and a communication distance of up to 100 meters.

[0173] (4) Monitoring circuit

[0174] The monitoring circuit includes three parts: digital input, analog input, and data acquisition module. Digital input is used to detect the switch status of each subsystem, dry contact signals, etc.; analog input is connected to various sensors to detect analog parameter such as voltage, current, power, temperature of the system; the data acquisition module periodically collects these data and uploads them to the host computer through the CAN bus.

[0175] 4. System working process

[0176] The main working process of this system is as follows:

[0177] (1) Normal state

[0178] Under normal power supply conditions, the main power supply and the standby power supply are parallel online and supply power in parallel through a parallel inverter circuit. The voltage phases of the two power supplies are synchronized through the SPWM modulation algorithm. The dynamic current limiting circuit is in a fully conductive state and does not generate impedance. At this time, the system real-time collects data such as grid voltage, current, power, harmonic content, etc., and after uploading to the intelligent judgment layer, it is predicted by the ARIMA model in a rolling manner.

[0179] (2) Abnormal warning

[0180] If the ARIMA model predicts that the voltage or current will exceed the set safety threshold at a certain moment 1 second later, the intelligent judgment layer immediately sends a preheating instruction to the coordination control layer.

[0181] For switching preheating, the coordination control layer controls the main and standby power inverters to enter the parallel state and simultaneously controls the preheating of the switching circuit.

[0182] For current-limiting preheating, the coordination control layer calculates the target current-limiting equivalent impedance and sends it to the current-limiting execution unit through the optical fiber channel. The current-limiting execution unit performs encoded preheating on the MOSFETs of each branch.

[0183] (3) Switching

[0184] When reaching the abnormal moment, for switching, the execution layer receives the switching instruction and immediately controls the standby inverter to output a voltage phase slightly lower than that of the main power supply. Through the current-loop feedback control of the parallel inverter circuit, the two-way current will be smoothly switched within a few milliseconds to achieve seamless switching.

[0185] (4) Dynamic current limiting

[0186] When reaching the abnormal moment, for overload current limiting, after the execution layer receives the current-limiting instruction, it will immediately change the conduction state of the current-limiting branch to make the total current-limiting resistance equal to the target value. Due to the fast response characteristic of the metal-oxide-semiconductor field-effect transistor, the current limiting will take effect within a few microseconds to timely limit the current within the safe range.

[0187] (5) Monitoring and alarming

[0188] During the switching or current-limiting process, the system will monitor parameters such as the grid voltage, current, power, and temperature in real time. Once an abnormality is detected, it will immediately send an alarm to the host computer by wired or wireless means, and at the same time trigger the intelligent diagnosis module to conduct fault troubleshooting.

[0189] Another embodiment is also provided in the present invention. The difference from the above embodiment is that the prediction module is used to perform the following steps:

[0190] Step 1: Receive the real-time data transmitted by the acquisition unit, including voltage, current, and frequency;

[0191] Step 2: Based on the historical data, establish a time series model of voltage, current, and frequency;

[0192] Step 3: Initialize three grey wolves, representing voltage, current, and frequency respectively, and randomly assign an initial position to each grey wolf, representing the current state of the corresponding index;

[0193] Step 4: Input the real-time data into the time series model to evaluate the fitness values of the three grey wolves, that is, the deviation degree between the current states of the three indexes and the expected target states;

[0194] Step 5: According to the grey wolf optimization algorithm, simulate the leader-follower behavior of three grey wolves, adjust the positions of the three grey wolves to minimize the deviation of three indicators, and the adjusted positions of the three grey wolves represent the changing trends of the predicted voltage, current, and frequency.

[0195] Step 6: According to the adjusted positions of the three grey wolves, determine whether the preset switching threshold or current limiting threshold will be reached within the future prediction time.

[0196] Step 7: If it is predicted that the switching threshold or current limiting threshold will be reached, give an early warning with the preset early warning time as the lead time, and preheat the switching circuit or impedance adjustment circuit.

[0197] Step 8: Continuously update the real-time data, and repeat Steps 4 - 7 to dynamically adjust the prediction time and early warning time. The specific explanations are as follows:

[0198] The specific implementation of Step 1 is to transmit the real-time data collected by the acquisition unit, including multiple indicators such as voltage, current, and frequency, to the prediction module using wired or wireless data transmission methods. A data receiver is set in the prediction module to receive the real-time data transmitted by the acquisition unit. The data receiver can be in various forms such as a serial communication interface, an Ethernet interface, or a wireless communication interface.

[0199] The specific implementation of Step 2 is to store the historical data in a database or a data file. For each indicator such as voltage, current, and frequency, establish a corresponding time series model using time series analysis methods. Commonly used time series models include autoregressive moving average model (ARMA), autoregressive integrated moving average model (ARIMA), exponential smoothing model, etc. These time series models can capture the trends, periodicity, and random fluctuations of the data, so as to predict future data. The establishment of the model can be achieved using statistical analysis software or programming languages.

[0200] The specific implementation of Step 3 is to use the grey wolf optimization algorithm (GWO) to predict the three indicators of voltage, current, and frequency. First, regard the three indicators as three grey wolves, named alpha, beta, and delta respectively. Each grey wolf represents the current state of an indicator, which is represented by a vector, and the dimension of the vector is equal to the prediction time step. At the initialization, randomly assign an initial position vector to each grey wolf, representing the initial state of the corresponding indicator. Here, the "position" can be understood as a multi-dimensional vector representing the state.

[0201] The specific implementation of Step 4 is to input the real-time collected data into the established time series model to obtain the ideal target state sequence of the corresponding indicators within the prediction time range. Then, calculate the fitness values, that is, the deviation degrees, between the current position vectors of the three grey wolves and the ideal target state sequence. The fitness function can use the root mean square error (RMSE) or other distance functions. The role of this step is to evaluate the deviation between the current state and the ideal state, laying a foundation for the next optimization and adjustment.

[0202] The specific implementation of Step 5 is to use the mathematical iteration formula in the grey wolf optimization algorithm to simulate the leader-follower behavior of the three grey wolves, adjust the position vectors of the three grey wolves, and make them gradually approach the ideal target state sequence, so as to minimize the deviation of the three indicators. Specifically, the algorithm will determine a leader wolf (alpha), whose position vector is closest to the ideal target; the other two wolves (beta and delta) will gradually adjust their own position vectors and tend to the combined position of the alpha wolf and the ideal target. The iteration formula contains multiple parameters such as the distance weighting between wolves and the random walking vector, which are used to control the convergence speed and the global search ability. The iterative operation continues until the termination condition is met (such as reaching the maximum number of iterations or the fitness value is less than the threshold). The adjusted position vectors of the three grey wolves represent the changing trends of the predicted voltage, current, and frequency. The role of this step is to utilize the excellent performance of the grey wolf optimization algorithm to find the best state prediction sequence.

[0203] The specific implementation of Step 6 is to determine whether the preset switching threshold or current limiting threshold will be reached within the future prediction time range according to the adjusted position vectors of the three grey wolves (i.e., the prediction sequence). For voltage, the switching threshold can be set to 220 ± 10%, that is, 198V to 242V; for current, the current limiting threshold can be set to 16A. If there is voltage or current data in the prediction sequence that exceeds the corresponding threshold range, it is determined that the corresponding threshold will be reached. The role of this step is to detect abnormal situations in advance and prepare for the next warning.

[0204] The specific implementation of Step 7 is that if it is determined that the switching threshold or current limiting threshold will be reached, the system will send a warning signal to the operator with a preset warning time (such as 30 seconds) in advance, preheat the response devices such as the switching circuit or impedance adjustment circuit, and make them enter the ready state. The warning signal can be an audible and visual signal or other forms of notification. At the same time, the prediction module also needs to display information such as the warning time and the abnormal occurrence time on the operation interface. The role of this step is to make preparations in advance before the abnormality occurs to avoid passive response.

[0205] The specific implementation of step 8 is that the prediction module continuously receives the latest real-time data transmitted by the acquisition unit and repeats steps 4 to 7, that is, updates the time series model based on the new data, reruns the grey wolf optimization algorithm to optimize the positions of the three grey wolves, and determines whether the threshold is reached. If so, an early warning is issued. Due to the iterative nature of the algorithm, the new real-time data will continuously correct and adjust the prediction sequence, enabling it to dynamically adapt to the changes in the data. At the same time, the prediction module can dynamically adjust the prediction time range and early warning time according to the real-time situation to obtain the best anomaly detection and response effects. The function of this step is to achieve continuous and dynamic state prediction and anomaly early warning to ensure the timely response of the system.

[0206] In this embodiment, the grey wolf hunting algorithm (GWO) is used for the state prediction of voltage, current, and frequency. Compared with directly predicting based on historical curves, it has the following advantages and advanced features:

[0207] 1. Better global search ability

[0208] The grey wolf hunting algorithm draws on the leader-follower mechanism in wolf pack hunting and applies this behavior pattern to the optimization solution through mathematical modeling. Compared with the curve-based prediction method, GWO has stronger global search ability and is not easily trapped in local optimal solutions, thus being able to find a more accurate prediction sequence.

[0209] 2. More advantageous for nonlinear and dynamic systems

[0210] The changes in physical quantities such as voltage, current, and frequency are usually affected by various complex factors, showing nonlinear and dynamic characteristics. As an intelligent optimization algorithm, GWO is good at dealing with such nonlinear and dynamic problems. While the prediction method based on historical curves often assumes that the data follows a certain specific linear or nonlinear model, which may be difficult to accurately describe complex dynamic systems.

[0211] 3. Combining the advantages of multiple prediction models

[0212] The GWO prediction method organically combines the time series model (such as ARIMA) and the optimization algorithm, capable of integrating the advantages of both. The time series model can mine the hidden laws in historical data as the basis for the optimization algorithm; while the optimization algorithm can specifically adjust the prediction sequence to make it as close to the actual situation as possible. This way of model fusion significantly improves the accuracy and robustness of the prediction.

[0213] 4. Having strong adaptability and scalability

[0214] The prediction method based on GWO can conveniently adjust algorithm parameters (such as the number of iterations, step size factor, etc.) to adapt to different prediction scenarios and performance requirements. In addition, this method can also be extended to the prediction of other physical quantities (such as temperature, power, etc.), and has good generality. While the method based on curve prediction needs to re-model and tune parameters for each new prediction object, and its scalability is relatively poor.

[0215] Specifically, the principle of the present invention is that the active switching current-limiting control technology of the present invention integrates advanced prediction, decision-making, and execution circuits, and adopts an automatic control method to realize the intelligent management of switching and active current limiting.

[0216] In terms of switching control, the present invention introduces a time series prediction algorithm to predict the future state of the main power supply. Based on the prediction results, it judges whether the switching condition will occur, and makes switching preparations in advance. Once the switching condition is met, it immediately issues a switching instruction to start the switching process. Compared with passive manual monitoring, this active switching control with prediction and early warning greatly shortens the switching response time, and can almost synchronously switch to the standby power supply with the main power supply fault, effectively avoiding power interruption and ensuring the continuous and reliable power supply of critical loads.

[0217] The switching circuit adopts the seamless switching technology of parallel inverters. The output voltages of the two inverters are phase-synchronized, and the phase transitions smoothly during the switching process, avoiding voltage fluctuations and interruptions during switching. At the same time, this circuit uses semiconductor static switches for switching, with an extremely fast response speed, and the switching process can be completed in just a few milliseconds. This switching circuit has a compact structure, flexible and reliable control, and solves the defects of existing redundant parallel power supplies such as capacity limitation, large volume, and difficult control.

[0218] In terms of current-limiting control, the present invention adopts a circuit for dynamic impedance regulation, which can dynamically adjust the equivalent internal resistance according to the real-time condition of the load current, and limit the current within the safe threshold range. Compared with existing fixed current-limiting circuits, this dynamic current-limiting circuit can not only prevent power overload faults, but also avoid energy waste and output performance limitations under normal operating conditions.

[0219] The dynamic impedance regulation circuit is composed of multiple parallel controllable resistors (reactors). Each controllable resistor (reactor) is composed of a fixed resistor (reactance) in parallel with a semiconductor switch. By controlling the conduction state of the switch, the size of the total equivalent impedance can be precisely adjusted. The impedance control unit calculates the target impedance through Ohm's law and performs encoded control on the controllable resistors (reactors) to make the total equivalent impedance equal to the target value. This controllable impedance structure has an extremely fast response speed, and the impedance switching can be completed in just a few microseconds, which can promptly suppress the instantaneous steep increase of the current and prevent the occurrence of overload faults.

[0220] Like the switching circuit, this current-limiting circuit also adopts advanced power electronic devices and high-speed control algorithms, with timely response and precise control. While ensuring the safety and reliability of the power supply system, it also maximizes the normal output performance of the power source and avoids unnecessary restrictions on the power supply capacity.

[0221] By organically combining the three links of prediction, switching, and current limiting, the present invention constructs a complete active high-reliability power supply control system.

[0222] The prediction link is responsible for collecting power grid data in real time, establishing an ARIMA time series prediction model, accurately predicting the trends of voltage, current, and frequency in a future period of time, and determining whether the switching or current-limiting threshold conditions will be reached. If they will be reached, a preheating signal is sent to the switching control unit or the impedance control unit in advance, so that the corresponding execution circuit can make preparations in advance.

[0223] After receiving the preheating signal from the prediction module, the switching link immediately charges the backup power supply and detects its state. At the same time, it preheats the parallel inverter and the switching control circuit. Once the switching instruction is received, the switching action can be completed within a few milliseconds to achieve seamless switching between the main and backup power supplies.

[0224] After receiving the preheating signal from the prediction module, the current-limiting link calculates the target equivalent impedance value to be adjusted and preheats the switching state of the controllable impedance unit. Once the current-limiting instruction is received, the impedance adjustment can be completed within a few microseconds to limit the current within the safe threshold.

[0225] The above is only the specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention can easily think of changes or substitutions, which should all be covered by the protection scope of the present invention.

Claims

1. An automatic switching impedance current limiting device, characterized in that, Including: A main control unit, a collection unit, a switching unit, and a current limiting unit; The main control unit is used to judge whether switching or current limiting operations are required according to the data input by the collection unit, and issue corresponding control instructions; The collection unit is used to collect the voltage, current, and frequency of the input power supply in real time, and transmit this data to the main control unit as the basis for switching and current limiting criteria; The switching unit is used to quickly switch from the main power supply to the standby power supply under the control of the switching instruction of the main control unit to achieve seamless power supply switching; The current limiting unit is used to adjust the equivalent impedance according to the current limiting instruction of the main control unit, so as to limit the current output by the currently online power supply within a safe range; Among them, the main control unit includes a prediction module and a judgment module. The prediction module is used to give a warning in advance with a preset warning time according to the parameters collected in real time, and preheat the switching circuit or the impedance adjustment circuit; the judgment module is used to judge whether it is necessary to immediately start switching or current limiting according to the parameters collected in real time. When it is necessary to immediately start switching or current limiting, immediately send a switching instruction to the switching control unit or send the impedance amount current limiting instruction to the impedance control unit; The prediction module is used to execute the following steps: Step 1: Receive the real-time data transmitted by the collection unit, including voltage, current, and frequency; Step 2: Based on historical data, establish a time series model of voltage, current, and frequency; Step 3: Initialize three grey wolves, which represent voltage, current, and frequency respectively, and randomly assign an initial position to each grey wolf, which represents the current state of the corresponding index; Step 4: Input the real-time data into the time series model, and evaluate the fitness values of the three grey wolves, that is, the deviation degree between the current states of the three indexes and the expected target state; Step 5: According to the grey wolf hunting algorithm, simulate the leader-follower behavior of the three grey wolves, adjust the positions of the three grey wolves to minimize the deviation of the three indexes, and the adjusted positions of the three grey wolves represent the predicted change trends of voltage, current, and frequency; Step 6: According to the adjusted positions of the three grey wolves, judge whether the preset switching threshold or current limiting threshold will be touched within the future prediction time; Step 7: If it is predicted that the switching threshold or current limiting threshold will be touched, give a warning in advance with a preset warning time, and preheat the switching circuit or the impedance adjustment circuit; Step 8: Continuously update the real-time data, and repeat steps 4-7 to dynamically adjust the prediction time and warning time; The impedance adjustment circuit includes a controllable impedance unit and an impedance control module. The controllable impedance unit is composed of multiple controllable resistors or reactors connected in parallel and can dynamically adjust the equivalent impedance. The impedance control module includes a controller and an encoder. The controller calculates the target impedance R' according to The encoder encodes the target impedance R' into a switch control code, and the controllable impedance unit adjusts the total equivalent impedance to the target impedance R' according to the control code. The preheating impedance adjustment circuit means pre-encoding the impedance control module, that is, the controller calculates the target impedance R' according to The encoder encodes R' into a switch control code and stores it. V is the given voltage, and I max is the current limiting threshold, Load impedance.

2. The automatic switching impedance current limiting device according to claim 1, wherein, The judgment module is used to execute the following steps: S21: Receive the real-time data transmitted by the collection unit, including voltage, current, and frequency; S22: Compare the real-time data with the preset switching threshold or current limiting threshold to judge whether the switching or current limiting condition has been touched; S23: If the switching condition is touched, immediately send a switching instruction to the switching control unit; S24: If the current limiting condition is touched, calculate the impedance amount to be adjusted, and immediately send the impedance amount current limiting instruction to the impedance control unit; S25: Continuously monitor the real-time data, repeat steps S21-S24, and make switching or current limiting decisions in real time.

3. An automatic switching impedance current limiting device according to claim 1, characterized in that, The specific steps of step 6 include: setting the switching voltage threshold as , where is the rated voltage; setting the switching frequency threshold as , where is the rated frequency; setting the current limiting threshold as , where is the rated current; comparing the predicted future voltage and frequency sequences with the corresponding switching threshold intervals, and comparing the real-time current value with the current limiting threshold. If there is a situation where the threshold is exceeded during the prediction time, it is determined that the switching or current limiting threshold will be reached.

4. An automatic switching impedance current limiting device according to claim 1, characterized in that, The specific steps of step 7 include: setting the warning time as T seconds. When it is predicted that the switching threshold will be reached after T seconds, the prediction module of the main control unit sends a preheating signal to the switching control unit. After receiving this signal, the switching control unit charges the backup power supply, detects the status of the backup power supply, and preheats the switching circuit to make the switching circuit enter the ready state. When it is predicted that the current limiting threshold will be reached after T seconds, the prediction module of the main control unit sends a preheating signal to the impedance control unit. The impedance control unit calculates the impedance amount to be adjusted according to this signal and preheats the impedance adjustment circuit.

5. An automatic switching impedance current limiting device according to claim 1, characterized in that, The switching circuit includes a main power supply switching module, a backup power supply switching module, a switching control module, and a parallel inverter module. Both the main power supply switching module and the backup power supply switching module include a static switch and a protection unit. The static switch uses a thyristor or an IGBT. The switching control module consists of a controller, a drive circuit, and a timing logic circuit, and coordinates the actions of the main and backup power supply switching modules after receiving a switching instruction. The parallel inverter module includes two parallel inverter circuits and realizes seamless switching based on the orthogonal vector inversion control algorithm. The preheating of the switching circuit means: powering on the parallel inverter module and the switching control module for 2 to 3 times the preset warning time.

6. The automatic switching impedance current limiting device according to claim 2, wherein The specific steps of step S23 include: when the judgment module finds that the switching condition has been reached, it immediately sends a switching instruction to the switching control unit. The switching control unit detects the status of the backup power supply and sends a switching signal, controls the switching circuit to separate the load from the main power supply and connect it to the backup power supply, controls the parallel inverters of the main power supply and the backup power supply to achieve seamless switching, and finally shuts down the main power supply.

7. An automatic switching impedance current limiting device according to claim 2, characterized in that, The specific steps of step S24 include: when the judgment module finds that the current limiting condition has been reached, it calculates the equivalent impedance amount to be adjusted according to the real-time current value, and immediately sends a corresponding current limiting instruction of the impedance amount to the impedance control unit. The impedance control unit calculates the target impedance R' according to the current value in the instruction and controls the controllable impedance unit to adjust the total equivalent impedance to R', so as to limit the current within a safe range.

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