A short-circuit fault handling method, device, equipment and medium

Abstract

The present application discloses a short-circuit fault processing method, device, equipment and medium, relating to the field of energy storage power distribution, including: determining whether a short-circuit fault occurs in the power grid; if the short-circuit fault occurs, determining a duty cycle limit gradient based on the current current slope, current value and output terminal support capacitor voltage; reducing the upper limit of the duty cycle of the PWM signal based on the duty cycle limit gradient to limit the short-circuit current; when it is monitored that the circuit breaker removes the short-circuit fault, determining a duty cycle release gradient based on the current current slope, current value and output terminal support capacitor voltage; and increasing the upper limit of the duty cycle of the PWM signal based on the duty cycle release gradient to limit the current passing through the DC output terminal of the energy storage power distribution system. The present application can avoid the system shutdown caused by the short-circuit phenomenon and quickly and smoothly restore the energy storage power distribution system to the normal working state after the fault is removed.

Description

Technical Field

[0001] The present invention relates to the field of energy storage power distribution, and particularly to a short - circuit fault handling method, device, equipment and medium. Background Art

[0002] In an energy storage power distribution system, a bidirectional DC / DC power converter is used to achieve energy exchange between the battery and the power grid. However, since the bidirectional DC / DC power converter often adopts a PI (Proportional Integral) control strategy, the characteristic of its small damping will cause an over - current phenomenon when a short - circuit fault occurs at the output end of the system, which greatly threatens the safety of the system and operators.

[0003] In the prior art, the fault current generated by a short - circuit fault can be limited by adding a current limiter to the energy storage power distribution system. However, since the protection mechanism of the current limiter will be quickly triggered to cut off or limit the current when a short - circuit fault is detected. And after the fault is removed, its protection mechanism still remains in the locked state. Therefore, the system cannot resume the normal working state after removing the point where the short - circuit fault occurs.

[0004] In summary, how to avoid the system shutdown caused by the short - circuit phenomenon and quickly and smoothly resume the normal working state after the fault is removed is an urgent problem to be solved at present. Summary of the Invention

[0005] In view of this, the purpose of the present invention is to provide a short - circuit fault handling method, device, equipment and medium to avoid the occurrence of over - current phenomenon and quickly and smoothly restore the energy storage power distribution system to the normal working state after the fault is removed. The specific solutions are as follows:

[0006] In a first aspect, the present application provides a short - circuit fault handling method applied to an energy storage power distribution system; wherein, the energy storage power distribution system includes a DC / DC power converter, and the method includes:

[0007] Judge whether a short - circuit fault occurs in the power grid;

[0008] If the short - circuit fault occurs, determine the duty - cycle limit gradient based on the current slope, current value and output - terminal support capacitor voltage at present;

[0009] Based on the duty - cycle limit gradient, reduce the upper limit of the duty - cycle of the PWM signal to limit the short - circuit current;

[0010] When it is monitored that the circuit breaker removes the short - circuit fault, determine the duty - cycle release gradient based on the current slope, current value and output - terminal support capacitor voltage at present;

[0011] Based on the duty cycle release gradient, increase the upper limit of the duty cycle of the PWM signal to limit the current passing through the DC output terminal of the energy storage and power distribution system.

[0012] Optionally, determining the duty cycle limit gradient based on the current slope, current value, and output terminal support capacitor voltage includes:

[0013] Taking the product of the current slope and the current slope coefficient as the first duty cycle limit gradient; wherein, the current slope coefficient is negative;

[0014] Taking the product of the current value and the current value coefficient as the second duty cycle limit gradient; wherein, the current value coefficient is negative;

[0015] Taking the product of the difference between the current output terminal support capacitor voltage and the lower limit value of the capacitor voltage and the capacitor voltage coefficient as the third duty cycle limit gradient; wherein, the capacitor voltage coefficient is negative;

[0016] Taking the sum of the first duty cycle limit gradient, the second duty cycle limit gradient, and the third duty cycle limit gradient as the current duty cycle limit gradient.

[0017] Optionally, determining the duty cycle release gradient based on the current slope, the current value, and the output terminal support capacitor voltage includes:

[0018] Determining the first duty cycle release gradient based on the current slope and the first duty cycle release coefficient, and the specific formula is as follows:

[0019] ;

[0020] wherein, the is the first duty cycle release gradient, is the first duty cycle release coefficient, is the current slope, is the exponential function;

[0021] Determining the second duty cycle release gradient based on the current value, the rated current, and the second duty cycle release coefficient, and the specific formula is as follows:

[0022] ;

[0023] wherein, the is the second duty cycle release gradient, is the second duty cycle release coefficient, is the rated current, is the current value;

[0024] Determine the third duty cycle release gradient based on the current output terminal support capacitor voltage, the capacitor rated voltage, and the third duty cycle release coefficient. The specific formula is as follows:

[0025] ;

[0026] Wherein, the is the third duty cycle release gradient, is the third duty cycle release coefficient, is the capacitor rated voltage, is the current output terminal support capacitor voltage;

[0027] Take the sum of the first duty cycle release gradient, the second duty cycle release gradient, and the third duty cycle release gradient as the current duty cycle release gradient.

[0028] Optionally, determining whether a short - circuit fault occurs in the power grid includes:

[0029] Obtain the predicted current slope to determine whether the predicted current slope is greater than the defined slope boundary value; if it is greater, it is determined that the short - circuit fault occurs in the power grid;

[0030] Or, obtain the current value to determine whether the current value is greater than the short - circuit current limiting boundary value; if it is greater, it is determined that the short - circuit fault occurs in the power grid;

[0031] Or, obtain the current output terminal support capacitor voltage to determine whether the current output terminal support capacitor voltage is less than the minimum capacitor voltage boundary value; if it is less, it is determined that the short - circuit fault occurs in the power grid.

[0032] Optionally, determining whether the predicted current slope is greater than the defined slope boundary value; if it is greater, it is determined that the short - circuit fault occurs in the power grid, includes:

[0033] Based on the current output terminal support capacitor voltage and the current value, determine the predicted current slope through a current slope prediction model;

[0034] When the predicted current slope is greater than the defined slope boundary value, it is determined that the short - circuit fault occurs in the power grid.

[0035] Optionally, the current slope prediction model is a linear regression model obtained based on historical current slopes and their corresponding system states.

[0036] Optionally, based on the duty cycle limit gradient, reducing the upper limit of the PWM signal duty cycle to limit the short - circuit current, includes:

[0037] Based on the duty cycle limit gradient, by switching the PI parameters, reduce the upper limit of the duty cycle of the PWM signal to limit the short-circuit current.

[0038] In a second aspect, the present application provides a short-circuit fault processing device applied to an energy storage power distribution system. Among them, the energy storage power distribution system includes a DC / DC power converter, including:

[0039] A fault judgment module for judging whether a short-circuit fault occurs in the power grid;

[0040] A first gradient calculation module for, if the short-circuit fault occurs, determining a duty cycle limit gradient based on the current current slope, current value and output terminal support capacitor voltage;

[0041] A first duty cycle adjustment module for reducing the upper limit of the duty cycle of the PWM signal based on the duty cycle limit gradient to limit the short-circuit current;

[0042] A second gradient calculation module for, when it is monitored that the circuit breaker removes the short-circuit fault, determining a duty cycle release gradient based on the current current slope, current value and output terminal support capacitor voltage;

[0043] A second duty cycle adjustment module for increasing the upper limit of the duty cycle of the PWM signal based on the duty cycle release gradient to limit the current passing through the DC output terminal of the energy storage power distribution system.

[0044] In a third aspect, the present application provides an electronic device, including:

[0045] A memory for storing a computer program;

[0046] A processor for executing the computer program to implement the above short-circuit fault processing method.

[0047] In a fourth aspect, the present application provides a computer-readable storage medium for storing a computer program. Among them, when the computer program is executed by a processor, the above short-circuit fault processing method is implemented.

[0048] As described above, in the energy storage and power distribution system, if a short - circuit fault occurs, the duty - cycle limit gradient at the current moment can be continuously calculated through the current slope, current value, and the voltage of the output - end support capacitor at the current moment. Meanwhile, based on this duty - cycle limit gradient, the upper limit of the PWM (Pulse Width Modulation) duty - cycle is adjusted to accurately control the current at the DC output end of the energy storage and power distribution system not to exceed the safety threshold. Therefore, when a short - circuit fault occurs in the system, the change in the system current can be responded to in real - time, and a quick response can be made to avoid over - current phenomena from damaging the system components. In addition, while limiting the current at the DC output end of the energy storage and power distribution system, the short - circuit fault will trigger the circuit breaker to trip, removing the faulty point. At this time, by calculating the current duty - cycle release gradient through the current slope, current value, and the voltage of the output - end support capacitor, the PWM duty - cycle can be gradually relaxed, enabling the system to quickly and smoothly resume normal operation. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the drawings described below are only the embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on the provided drawings.

[0050] Figure 1 It is a flowchart of a short - circuit fault handling method disclosed in the present application;

[0051] Figure 2 It is a flowchart of a mode - switching disclosed in the present application;

[0052] Figure 3 It is a schematic structural diagram of a short - circuit fault handling device disclosed in the present application;

[0053] Figure 4 It is a structural diagram of an electronic device disclosed in the present application. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0054] The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of them. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention.

[0055] In an energy storage and power distribution system, a bidirectional DC / DC power converter is used to achieve energy exchange between the battery and the power grid. However, since the bidirectional DC / DC power converter often adopts a PI (Proportional Integral) control strategy, the characteristic of its small damping will cause an overcurrent phenomenon when a short-circuit fault occurs at the output end of the system, which greatly threatens the safety of the system and operators.

[0056] In the prior art, the fault current generated by a short-circuit fault can be limited by adding a current limiter to the energy storage and power distribution system. However, since the protection mechanism of the current limiter will be quickly triggered when a short-circuit fault is detected, the current will be cut off or limited. And after the fault is removed, its protection mechanism still remains in the locked state. Therefore, the system cannot resume its normal working state after removing the point where the short-circuit fault occurs.

[0057] For this reason, the present application provides a short-circuit fault handling solution to improve the response speed of the DC / DC power converter under short-circuit faults, avoid the occurrence of overcurrent phenomena, and quickly and smoothly resume the normal working state after the fault is removed.

[0058] See Figure 1 、 2 As shown in

[0059] Step S11: Determine whether a short-circuit fault has occurred in the power grid.

[0060] In this embodiment, the power grid is a complex system. When a short-circuit fault occurs in the power grid, a large current far exceeding the safe range will be generated instantaneously, which greatly threatens the safety of the system and external operators. Therefore, in order to respond to power grid faults in a timely manner and ensure the safety of equipment and personnel, it is necessary to continuously monitor the power grid and determine whether a fault has occurred.

[0061] In this embodiment, various methods can be used to determine whether a short-circuit fault has occurred in the power grid.

[0062] In the first specific implementation manner, the predicted current slope is obtained to determine whether the predicted current slope is greater than the defined slope boundary value; if it is greater, it is determined that a short-circuit fault has occurred in the power grid. It can be understood that due to the normal switching of loads, the start and stop of electrical equipment, etc., the changes caused are usually gradual and will not show sudden large changes. Therefore, when the power grid is operating normally, the current in the power grid is stable, changes gently with time, and its current slope is also small.

[0063] When a short - circuit fault occurs in the power grid, due to the sharp increase in current, at the moment of short - circuit, the current will rapidly rise from the normal operating value to a short - circuit current value far higher than the normal level. During this process, the rate of change of current with time is very large, that is, the current slope shows an obvious mutation. Among them, calculating the current slope k at the current moment n has the following specific formula:

[0064] ;

[0065] Among them, is the current difference between the current moment and the previous moment, is the current value at the current moment time, is the current value at the previous moment time.

[0066] ;

[0067] Among them, is the sampling interval, that is, the time interval between the current moment and the previous moment.

[0068] Furthermore, based on the current output - terminal support capacitor voltage and the current value, through the current - slope prediction model, the predicted current slope is determined; when the predicted current slope is greater than the defined slope boundary value, it is determined that a short - circuit fault has occurred. In the initial stage of a short - circuit fault in the power grid, even before the current value of the power grid reaches the action threshold of the protection device, the predicted current slope for the next moment can be obtained through the current - slope prediction model to determine whether a short - circuit fault is about to occur, detect the abnormal change of the current slope, and thus send out an early warning signal in advance, which can gain valuable time for quickly cutting off the fault and protecting the safety of the equipment.

[0069] In this embodiment, the current - slope prediction model is a linear regression model obtained based on historical current slopes and their corresponding system states. By sampling the current data at the output terminal under different working conditions at high speed, in order to utilize the historical current - slope data 、 、……、 and their corresponding working conditions, slope calculation and slope - curve fitting are realized. The specific formula of the obtained linear regression model is as follows:

[0070] ;

[0071] Among them, is the predicted current slope for the next moment time, 、 、 and are the coefficients of this linear regression model, is the input voltage at the current moment , is the load current at the current moment .

[0072] It can be understood that , , and can be determined by combining the simulation data of Simulink and the actual experimental data under different working conditions, and the above limited slope boundary value k th needs to be set according to the rated working condition data performance of the energy storage power distribution system and the short-circuit withstand capacity determined by the device selection. Therefore, when the predicted current slope k n+1 is greater than the limited slope boundary value , it can be judged that a short-circuit fault is about to occur, and corresponding operations need to be triggered to avoid the overcurrent phenomenon caused by the short-circuit fault.

[0073] It should be noted that, on the one hand, to obtain an accurate predicted current slope, high-precision real-time measurement and fast and accurate calculation of the current are required. This places high requirements on the measurement equipment and data processing system. If the measurement accuracy is insufficient or the calculation error is large, misjudgment or missed judgment may occur. On the other hand, there are various interference factors in the power system, such as lightning strikes, starting of large motors, switching of capacitors, etc. These operations may cause instantaneous fluctuations or changes in the current, thus affecting the accuracy of the predicted current slope. Therefore, in order to ensure the accuracy of short-circuit fault judgment, in addition to judging whether a short-circuit fault occurs in the power grid through the predicted current slope, multiple methods can also be set simultaneously in the energy storage power distribution system to comprehensively judge the working conditions of the system.

[0074] In the second specific implementation manner, the current value at the current moment is obtained to judge whether the current value at the current moment is greater than the short-circuit current limiting boundary value; if it is greater, it is determined that a short-circuit fault has occurred in the power grid. It can be understood that when a short-circuit fault occurs in the power grid, the impedance of the circuit will decrease sharply. Under the condition that the power supply voltage remains basically unchanged, the decrease in impedance will inevitably lead to a sharp increase in the current. Therefore, a significant change in the current value is a remarkable feature of a short-circuit fault. By monitoring the current value and comparing the above current value with the short-circuit current limiting boundary value to capture this abnormal change, it is possible to judge whether a short-circuit fault has occurred in the power grid.

[0075] In the third specific implementation, the current output terminal support capacitor voltage is obtained to determine whether the current output terminal support capacitor voltage is less than the minimum capacitor voltage boundary value; if it is less, it is determined that a short - circuit fault has occurred in the power grid. The support capacitor smooths voltage fluctuations by storing and releasing charges, ensuring that the voltage output by the power grid remains within a relatively stable range, providing a stable power supply for various electrical devices connected to the power grid, and maintaining the stability of the output terminal voltage. It can be understood that when a short - circuit fault occurs in the power grid, the impedance in the circuit suddenly decreases, resulting in a sharp increase in current and causing a sudden change in the state of the circuit. At this time, the support capacitor will start to discharge rapidly to maintain the voltage in the circuit. However, when the current caused by the short - circuit fault is too large, the discharge speed of the support capacitor far exceeds the normal discharge speed, and the stored charge in it rapidly decreases, resulting in a rapid drop in the voltage across the support capacitor. Therefore, by monitoring the output terminal support capacitor voltage and comparing the above - mentioned output terminal support capacitor voltage with the minimum capacitor voltage boundary value, it is possible to determine whether a short - circuit fault has occurred in the power grid.

[0076] It can be understood that to achieve the judgment of the power grid short - circuit fault, multiple sensors need to be arranged at key parts of the DC - DC power converter to monitor the output terminal support capacitor voltage and current values in real time, and input the monitored data and the real - time feedback of the power grid working state and load changes into the fuzzy logic controller in real time. Based on the obtained data, it is judged whether a short - circuit fault has occurred in the power grid or whether the short - circuit fault has been successfully removed, so as to further judge whether the energy storage power distribution system needs to perform mode switching. Among them, the energy storage power distribution system includes a current - limiting mode, a rapid - recovery mode, and a steady - state mode. Through real - time evaluation of the system working conditions, smooth switching can be performed among the three modes.

[0077] As Figure 2 shown, the current value and voltage value of the system can be sampled at high speed through a current sensor and a voltage sensor, and the obtained high - speed sampling signals are processed and analyzed to judge whether a fault will occur at the next moment. If not, the system remains in normal operation, that is, the steady - state mode. If so, the system needs to be switched to the current - limiting mode to limit the current within a safe range and protect the safety of the system. In addition, after it is monitored that the DC circuit breaker trips within 500 ms to remove the fault point, the current - limiting mode can be switched to the rapid - recovery mode to quickly and smoothly restore the system to the rated state operation, that is, switch back to the steady - state mode. It can be understood that if the DC circuit breaker does not remove the fault point within 500 ms, the system needs to enter the fault mode at this time to issue an alarm, and at the same time block the switching tubes, disconnect all circuit breakers and shut down to protect the safety of the system and personnel.

[0078] In addition, the above - mentioned 500 - ms time limit can be adjusted according to the actual working conditions of the system and device settings.

[0079] Step S12: If a short - circuit fault occurs, determine the duty - cycle limit gradient based on the current slope, current value, and the voltage of the output - terminal support capacitor at the current moment.

[0080] In this embodiment, after detecting that a short - circuit fault occurs in the power grid or predicting that a short - circuit fault in the power grid is about to occur according to the above method, in order to avoid the occurrence of over - current phenomenon, it is necessary to convert the above energy - storage power - distribution system into a current - limiting mode to reduce the output current.

[0081] Furthermore, in order to accurately control the current and ensure that the current value of the system does not exceed the safety threshold during the short - circuit fault, the current slope, current value, and the magnitude of the voltage of the output - terminal support capacitor of the power - distribution system can be comprehensively considered to determine the duty - cycle limit gradient. It should be noted that the duty - cycle limit gradient is mainly a parameter that restricts the reduction rate of the duty cycle, that is, the duty - cycle limit gradient stipulates the maximum change amplitude of the duty cycle within a unit time to ensure that the duty cycle changes smoothly, and further makes the current change relatively gently to avoid the impact on the circuit caused by current mutation. In a DC - DC power converter, the duty - cycle limit gradient can prevent the duty cycle from suddenly increasing, resulting in an excessive output current, thereby protecting circuit components such as switching transistors, inductors, and loads from the impact of excessive current.

[0082] In this embodiment, the product of the current slope at the current moment and the current - slope coefficient is used as the first duty - cycle limit gradient; where the current - slope coefficient is a negative value; its specific formula is as follows:

[0083] ;

[0084] where is the first duty - cycle limit gradient, is the current - slope coefficient, is the current slope at the current moment.

[0085] It should be noted that the current slope reflects the speed of current change. Therefore, if the current slope at the current moment is large, it indicates that the current of the current short - circuit grows rapidly, and a larger adjustment of the duty cycle is required to suppress the current rise. Therefore, the magnitude of the current slope is directly proportional to the absolute value of the duty - cycle limit gradient and inversely proportional to the duty - cycle limit gradient.

[0086] In this embodiment, the product of the current value at the current moment and the current - value coefficient is used as the second duty - cycle limit gradient; where the current - value coefficient is a negative value;

[0087] ;

[0088] where is the second duty - cycle limit gradient, is the current - value coefficient, is the current value at the current moment.

[0089] It should be noted that if the current value is large, the duty cycle needs to be adjusted more actively to limit the current value within the safe range as soon as possible. Therefore, the current value is directly proportional to the absolute value of the duty cycle limit gradient and inversely proportional to the duty cycle limit gradient.

[0090] In this embodiment, the product of the difference between the current output terminal support capacitor voltage and the lower limit value of the capacitor voltage and the capacitor voltage coefficient is used as the third duty cycle limit gradient; wherein, the capacitor voltage coefficient is negative;

[0091] ;

[0092] Wherein, is the third duty cycle limit gradient, is the capacitor voltage coefficient, is the lower limit value of the capacitor voltage, is the current output terminal support capacitor voltage.

[0093] It should be noted that since a lower support capacitor voltage indicates that the support capacitor has discharged more at this time and the system stability is more threatened, the duty cycle needs to be adjusted more carefully to avoid further decrease in the support capacitor voltage and system instability due to improper duty cycle adjustment.

[0094] Furthermore, the sum of the first duty cycle limit gradient, the second duty cycle limit gradient, and the third duty cycle limit gradient is used as the current duty cycle limit gradient . The specific formula is as follows:

[0095] ;

[0096] In addition, since the first duty cycle limit gradient, the second duty cycle limit gradient, and the third duty cycle limit gradient all reflect the amplitude of the duty cycle decrease, their corresponding coefficients are all negative.

[0097] Step S13, based on the duty cycle limit gradient, reduce the upper limit of the duty cycle of the PWM signal to limit the short-circuit current.

[0098] In this embodiment, based on the current output terminal support capacitor voltage, current value, and current slope, the magnitude of the duty cycle limit gradient is calculated and adjusted in real time according to the above algorithm, and the upper limit of the duty cycle of the PWM signal is slowly reduced based on this duty cycle limit gradient, so that the system current is always within the safe threshold during the short-circuit fault process.

[0099] In this embodiment, as Figure 2As shown, the PI parameters are switched, the gradient is limited based on the duty cycle, and the upper limit of the duty cycle of the PWM signal is reduced to limit the short-circuit current. It can be understood that the proportional parameter determines the response speed and adjustment strength of the controller to the error. Increasing the proportional parameter, the controller will respond more sensitively to the error, making the adjustment speed of the duty cycle faster, and enabling the output to approach the set value more quickly. The integral parameter is mainly used to eliminate the steady-state error of the system. During the duty cycle adjustment process, the integral link accumulates the error, and over time, gradually adjusts the duty cycle to make the output reach and stabilize at the set value. Therefore, after entering the current limiting mode, adjusting the PI parameters to more suitable parameters for the current limiting mode can enable the duty cycle to be adjusted quickly, and also enable the PI control to output the duty cycle under the limited state, restricting the current at the DC output end.

[0100] Step S14: When it is detected that the circuit breaker trips to cut off the short-circuit fault, determine the duty cycle release gradient based on the current slope, current value, and the voltage of the output terminal support capacitor.

[0101] In this embodiment, after a power grid fault occurs, the circuit breaker at the corresponding position will trip quickly to cut off the short-circuit fault. At this time, it is necessary to gradually restore the energy storage power distribution system to the normal working state. Therefore, it is necessary to convert the system to the fast recovery mode and calculate the current duty cycle release gradient based on the current slope, current value, and the voltage of the output terminal support capacitor. It can be understood that similar to the duty cycle limit gradient, the duty cycle release gradient is mainly a parameter that limits the increase rate of the duty cycle, that is, the duty cycle release gradient stipulates the maximum change amplitude of the duty cycle per unit time to ensure the smooth change of the duty cycle.

[0102] In this embodiment, determine the first duty cycle release gradient based on the current slope and the first duty cycle release coefficient. The specific formula is as follows:

[0103] ;

[0104] Wherein, is the first duty cycle release gradient, is the first duty cycle release coefficient, is the current slope, is the exponential function.

[0105] It can be understood that as the current slope decreases, it indicates that the current change is gentle at present. Therefore, the first duty cycle release gradient can be increased correspondingly to speed up the release of the duty cycle. As the current slope increases, it indicates that the current changes quickly, and the first duty cycle release gradient can be decreased correspondingly to slow down the release of the duty cycle and avoid current impact.

[0106] In this embodiment, based on the current current value, the rated current, and the second duty cycle release coefficient, the second duty cycle release gradient is determined. The specific formula is as follows:

[0107] ;

[0108] Wherein, is the second duty cycle release gradient, is the second duty cycle release coefficient, is the rated current, is the current current value;

[0109] It can be understood that as the current value approaches the rated current, that is, the system is closer to the normal working state. The rated current of the device is the maximum current value at which it can operate stably for a long time. Therefore, when the current value gradually approaches the rated current, it indicates that the DC-DC power converter has the ability to withstand a larger load. At this time, accelerating the release speed of the duty cycle limit can allow the DC-DC power converter to fully exert its power conversion ability within the safe range and output more power to quickly restore the system to the normal working state.

[0110] In this embodiment, based on the current output terminal support capacitor voltage, the capacitor rated voltage, and the third duty cycle release coefficient, the third duty cycle release gradient is determined. The specific formula is as follows:

[0111] ;

[0112] Wherein, is the third duty cycle release gradient, is the third duty cycle release coefficient, is the capacitor rated voltage, is the current output terminal support capacitor voltage;

[0113] It should be noted that as the output terminal support capacitor voltage recovers and increases, the duty cycle limit can be released more actively. Because the output terminal support capacitor has the ability to store charge, when the output terminal support capacitor voltage increases, it indicates that its output power has the potential to increase. At this time, increasing the duty cycle limit gradient can utilize the energy stored in the capacitor to make the DC-DC power converter output more power to quickly restore the energy storage and power distribution system to the normal working state.

[0114] The sum of the first duty cycle release gradient, the second duty cycle release gradient, and the third duty cycle release gradient is used as the current duty cycle release gradient. At this time, the duty cycle release gradient The specific formula is as follows:

[0115] ;

[0116] Step S15: Based on the duty cycle release gradient, increase the upper limit of the duty cycle of the PWM signal to limit the current passing through the DC output terminal of the energy storage and power distribution system.

[0117] In this embodiment, based on the current output terminal support capacitor voltage, current value, and current slope, the magnitude of the duty cycle release gradient is calculated and adjusted in real time according to the above algorithm, and the upper limit of the duty cycle of the PWM signal is rapidly and gently increased based on this duty cycle release gradient, so that the voltage and current in the system gradually return to the normal level.

[0118] It should be noted that since the maximum value of the duty cycle is specified in the energy storage and power distribution system to prevent excessive current, when increasing the upper limit of the duty cycle of the PWM signal based on the duty cycle release gradient, it is necessary to ensure that the upper limit of the duty cycle is less than the maximum value of the duty cycle. As Figure 2 shown, after entering the current limiting mode, the maximum value of the duty cycle can be calculated based on the PI parameters.

[0119] From the above, it can be seen that in the energy storage and power distribution system, if a short circuit fault occurs, the duty cycle limit gradient at the current moment can be continuously calculated immediately through the current slope, current value, and output terminal support capacitor voltage at the current moment. At the same time, based on this duty cycle limit gradient, the upper limit of the PWM duty cycle is adjusted to accurately control the system current not to exceed the safety threshold. Therefore, it is possible to achieve real-time response to the change of the system current when a short circuit fault occurs in the system, and quickly respond to avoid damage to the system components caused by overcurrent phenomena. In addition, while limiting the system current, the short circuit fault will trigger the circuit breaker to trip, so that the faulty point is cut off. At this time, the duty cycle release gradient at the current moment is calculated through the current slope, current value, and output terminal support capacitor voltage at the current moment, and the duty cycle of the PWM can be gradually relaxed, so that the system can quickly and stably resume normal operation.

[0120] Correspondingly, as shown in Figure 3 this figure, an embodiment of the present application further provides a short circuit fault processing device applied to an energy storage and power distribution system; wherein, the energy storage and power distribution system includes a DC / DC power converter, and may include:

[0121] A fault judgment module 11, configured to judge whether a short circuit fault occurs in the power grid;

[0122] A first gradient calculation module 12, configured to determine a duty cycle limit gradient based on the current current slope, current value, and output terminal support capacitor voltage if a short circuit fault occurs;

[0123] A first duty cycle adjustment module 13, configured to reduce the upper limit of the duty cycle of the PWM signal based on the duty cycle limit gradient to limit the short circuit current;

[0124] The second gradient calculation module 14 is configured to, when it is detected that the circuit breaker cuts off the short-circuit fault, determine the duty ratio release gradient based on the current current slope, the current value, and the output terminal support capacitor voltage.

[0125] The second duty ratio adjustment module 15 is configured to increase the upper limit of the duty ratio of the PWM signal based on the duty ratio release gradient to limit the current passing through the DC output terminal of the energy storage power distribution system.

[0126] As can be seen from the above, in the energy storage power distribution system, if a short-circuit fault occurs, the duty ratio limit gradient at the current moment can be continuously calculated immediately through the current current slope, current value, and output terminal support capacitor voltage. At the same time, based on this duty ratio limit gradient, the upper limit of the PWM duty ratio is adjusted to accurately control the system current not to exceed the safety threshold. Therefore, when a short-circuit fault occurs in the system, the change of the system current can be responded to in real time, and a quick response can be made to avoid damage to the system components caused by overcurrent phenomena. In addition, while limiting the system current, the short-circuit fault will trigger the circuit breaker to trip, so that the faulty point is cut off. At this time, the duty ratio release gradient at the current moment is calculated through the current current slope, current value, and output terminal support capacitor voltage, and the duty ratio of the PWM can be gradually relaxed, enabling the system to quickly and stably resume normal operation.

[0127] In some specific embodiments, the first gradient calculation module 12 includes:

[0128] The first duty ratio limit gradient determination unit is configured to use the product of the current current slope and the current slope coefficient as the first duty ratio limit gradient; wherein, the current slope coefficient is a negative value;

[0129] The second duty ratio limit gradient determination unit is configured to use the product of the current current value and the current value coefficient as the second duty ratio limit gradient; wherein, the current value coefficient is a negative value;

[0130] The third duty ratio limit gradient determination unit is configured to use the product of the difference between the current output terminal support capacitor voltage and the lower limit value of the capacitor voltage and the capacitor voltage coefficient as the third duty ratio limit gradient; wherein the capacitor voltage coefficient is a negative value;

[0131] The duty ratio limit gradient determination unit is configured to use the sum of the first duty ratio limit gradient, the second duty ratio limit gradient, and the third duty ratio limit gradient as the current duty ratio limit gradient.

[0132] In some specific embodiments, the second gradient calculation module 14 includes:

[0133] The first duty cycle release gradient determination unit is configured to determine a first duty cycle release gradient based on the current current slope and a first duty cycle release coefficient. The specific formula is as follows:

[0134] ;

[0135] wherein, the is the first duty cycle release gradient, is the first duty cycle release coefficient, is the current current slope;

[0136] The second duty cycle release gradient determination unit is configured to determine a second duty cycle release gradient based on the current current value, the rated current, and a second duty cycle release coefficient. The specific formula is as follows:

[0137] ;

[0138] wherein, the is the second duty cycle release gradient, is the second duty cycle release coefficient, is the rated current, is the current current value;

[0139] The third duty cycle release gradient determination unit is configured to determine a third duty cycle release gradient based on the current output terminal support capacitor voltage, the capacitor rated voltage, and a third duty cycle release coefficient. The specific formula is as follows:

[0140] ;

[0141] wherein, the is the third duty cycle release gradient, is the third duty cycle release coefficient, is the capacitor rated voltage, is the current output terminal support capacitor voltage;

[0142] The duty cycle release gradient determination unit is configured to use the sum of the first duty cycle release gradient, the second duty cycle release gradient, and the third duty cycle release gradient as the current duty cycle release gradient.

[0143] In some specific embodiments, the fault determination module 11 includes:

[0144] The first fault determination unit is configured to obtain a predicted current slope to determine whether the predicted current slope is greater than a defined slope boundary value; if it is greater, it is determined that a short circuit fault has occurred in the power grid;

[0145] The second fault judgment unit is configured to obtain the current current value to determine whether the current current value is greater than the short - circuit current - limiting boundary value; if it is greater, it is determined that a short - circuit fault has occurred in the power grid;

[0146] The third fault judgment unit is configured to obtain the current output - terminal support capacitor voltage to determine whether the current output - terminal support capacitor voltage is less than the minimum capacitor voltage boundary value; if it is less, it is determined that a short - circuit fault has occurred in the power grid.

[0147] In some specific embodiments, the first fault judgment unit is specifically configured to determine the predicted current slope through a current - slope prediction model based on the current output - terminal support capacitor voltage and the current current value; when the predicted current slope is greater than the defined slope boundary value, it is determined that a short - circuit fault has occurred.

[0148] Among them, the current - slope prediction model is a linear regression model obtained based on historical current slopes and their corresponding system states.

[0149] In some specific embodiments, the first duty - cycle adjustment module 13 includes:

[0150] The first duty - cycle adjustment unit is configured to reduce the upper limit of the PWM signal duty - cycle based on the duty - cycle limit gradient by switching PI parameters to limit the short - circuit current.

[0151] Furthermore, an embodiment of the present application also discloses an electronic device, Figure 4 This is a structural diagram of an electronic device disclosed in the present application. The content in the figure should not be regarded as any limitation on the scope of use of the present application. The electronic device 20 may specifically include: at least one processor 21, at least one memory 22, a power supply 23, a communication interface 24, an input - output interface 25, and a communication bus 26. Among them, the memory 22 is used to store a computer program, and the computer program is loaded and executed by the processor 21 to implement the relevant steps in the short - circuit fault handling method disclosed in any of the foregoing embodiments. Additionally, the electronic device 20 in this embodiment may specifically be an electronic computer.

[0152] In this embodiment, the power supply 23 is used to provide operating voltages for each hardware device on the electronic device 20; the communication interface 24 can create a data - transmission channel between the electronic device 20 and external devices, and the communication protocol it follows is any communication protocol applicable to the technical solution of the present application, and no specific limitation is imposed here; the input - output interface 25 is used to obtain external input data or output data to the outside, and its specific interface type can be selected according to specific application requirements, and no specific limitation is made here.

[0153] In addition, as a carrier for storing resources, the memory 22 can be a read-only memory, a random access memory, a magnetic disk, an optical disc, etc. The resources stored thereon can include an operating system 221, a computer program 222, etc. The storage method can be transient storage or permanent storage.

[0154] Among them, the operating system 221 is used to manage and control each hardware device and the computer program 222 on the electronic device 20, and it can be Windows Server, Netware, Unix, Linux, etc. In addition to the computer program that can be used to complete the short-circuit fault processing method executed by the electronic device 20 disclosed in any of the foregoing embodiments, the computer program 222 can further include computer programs that can be used to complete other specific tasks.

[0155] Furthermore, the present application also discloses a computer-readable storage medium for storing a computer program; wherein, when the computer program is executed by a processor, the short-circuit fault processing method disclosed above is implemented. For the specific steps of this method, reference can be made to the corresponding content disclosed in the foregoing embodiments, and details will not be repeated here.

[0156] In this specification, each embodiment is described in a progressive manner. The key point of each embodiment is to illustrate the differences from other embodiments. For the same or similar parts among the embodiments, reference can be made to each other. For the device disclosed in the embodiment, since it corresponds to the method disclosed in the embodiment, the description is relatively simple, and reference can be made to the description of the method part for related parts.

[0157] Those skilled in the art can further realize that the units and algorithm steps of each example described in combination with the embodiments disclosed in this article can be implemented by electronic hardware, computer software, or a combination of the two. To clearly illustrate the interchangeability of hardware and software, the composition and steps of each example have been generally described according to functions in the above description. Whether these functions are executed in a hardware or software manner depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementation should not be considered to exceed the scope of this application.

[0158] The steps of the method or algorithm described in combination with the embodiments disclosed in this article can be directly implemented by hardware, a software module executed by a processor, or a combination of the two. The software module can be placed in a random access memory (RAM), internal memory, read-only memory (ROM), electrically programmable ROM, electrically erasable programmable ROM, register, hard disk, removable disk, CD-ROM, or any other form of storage medium well-known in the technical field.

[0159] Finally, it should also be noted that in this text, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the term "comprising", "including" or any other variant thereof is intended to cover non-exclusive inclusion, so that a process, method, article or device comprising a series of elements not only includes those elements, but also includes other elements not expressly listed, or further includes elements inherent to such process, method, article or device. Without further limitation, an element defined by the statement "comprising an..." does not exclude the presence of additional identical elements in the process, method, article or device comprising the said element.

[0160] The technical solutions provided in this application have been introduced in detail above. Specific examples are used in this text to elaborate on the principle and implementation manner of this application. The description of the above embodiments is only used to help understand the method and its core idea of this application; at the same time, for those of ordinary skill in the art, according to the idea of this application, there will be changes in the specific implementation manner and application scope. In summary, the content of this specification should not be construed as a limitation to this application.

Claims

1. A short circuit fault processing method, characterized in that: Applied to an energy storage and distribution system; wherein the energy storage and distribution system includes a DC / DC power converter, and the method includes: Determine whether a short circuit fault occurs in the power grid; If the short circuit fault occurs, a duty cycle limiting gradient is determined based on the current current slope, current value and output end support capacitor voltage, wherein the duty cycle limiting gradient is a parameter for limiting the duty cycle reduction rate; Based on the duty cycle limiting gradient, reducing the duty cycle upper limit of the PWM signal to limit the short-circuit current; When it is monitored that the circuit breaker cuts off the short circuit fault, a duty cycle release gradient is determined based on the current current slope, current value and output end support capacitor voltage, where the duty cycle release gradient is a parameter that limits the rate at which the duty cycle increases; Based on the duty cycle release gradient, increasing the duty cycle upper limit of the PWM signal to limit the current passing through the DC output terminal of the energy storage and distribution system; Wherein, based on the current current slope, current value and output end support capacitor voltage, the duty cycle limiting gradient is determined, including: The product of the current current slope and the current slope coefficient is used as the first duty cycle limiting gradient; wherein the current slope coefficient is a negative value; The product of the current current value and the current value coefficient is used as the second duty cycle limiting gradient; wherein the current value coefficient is a negative value; The product of the difference between the current output end supporting capacitor voltage and the capacitor voltage lower limit value and the capacitor voltage coefficient is used as the third duty cycle limiting gradient; wherein the capacitor voltage coefficient is a negative value; taking the sum of the first duty cycle limit gradient, the second duty cycle limit gradient and the third duty cycle limit gradient as the current duty cycle limit gradient; Wherein, based on the current current slope, current value and output end support capacitor voltage, determining the duty cycle release gradient includes: Determining a first duty cycle release gradient based on the current current slope and the first duty cycle release coefficient; Determining a second duty cycle release gradient based on the current current value, the rated current and the second duty cycle release coefficient; Determining a third duty cycle release gradient based on the current output end support capacitor voltage, capacitor rated voltage and a third duty cycle release coefficient; The sum of the first duty cycle release gradient, the second duty cycle release gradient and the third duty cycle release gradient is used as the current duty cycle release gradient.

2. The short circuit fault processing method according to claim 1, characterized in that: The formula for generating the first duty cycle release gradient is as follows: ； Among them, the The first duty cycle release gradient is, is the first duty cycle release coefficient, is the current slope of the current, is an exponential function; The formula for generating the second duty cycle release gradient is as follows: ； Among them, the For the second duty cycle release gradient, is the second duty cycle release coefficient, is the rated current, is the current value of the current; The formula for generating the third duty cycle release gradient is as follows: ； Among them, the is the third duty cycle release gradient, is the third duty cycle release coefficient, is the capacitor rated voltage, is the current output terminal supporting capacitor voltage.

3. The short circuit fault processing method according to claim 1, characterized in that: Determine whether a short circuit fault occurs in the power grid, including: Obtaining a predicted current slope to determine whether the predicted current slope is greater than a limited slope boundary value; if so, determining that the short circuit fault occurs in the power grid; Or, obtaining the current current value to determine whether the current current value is greater than the short-circuit current limiting boundary value; if greater than, determining that the short-circuit fault occurs in the power grid; Or, obtain the current output end supporting capacitor voltage to determine whether the current output end supporting capacitor voltage is less than the minimum capacitor voltage boundary value; if it is less than, determine that the short circuit fault occurs in the power grid.

4. The short circuit fault processing method according to claim 3, characterized in that: Determining whether the predicted current slope is greater than a limited slope boundary value; If it is greater than, determining that the short circuit fault occurs in the power grid includes: Based on the current output end supporting capacitor voltage and the current current value, the predicted current slope is determined by a current slope prediction model; When the predicted current slope is greater than the limited slope boundary value, it is determined that the short circuit fault occurs in the power grid.

5. The short circuit fault processing method according to claim 4, characterized in that: The current slope prediction model is a linear regression model obtained based on the historical current slope and its corresponding system state.

6. The short circuit fault processing method according to any one of claims 1 to 5, characterized in that: Based on the duty cycle limiting gradient, reducing the duty cycle upper limit of the PWM signal to limit the short-circuit current includes: Based on the duty cycle limit gradient, the duty cycle upper limit of the PWM signal is reduced by switching PI parameters to limit the short-circuit current.

7. A short circuit fault handling device, characterized in that: Applied to energy storage and distribution system; wherein the energy storage and distribution system includes a DC / DC power converter, including: A fault judgment module is used to judge whether a short circuit fault occurs in the power grid; A first gradient calculation module, used for determining a duty cycle limiting gradient based on a current current slope, a current value and an output end supporting capacitor voltage if the short circuit fault occurs; A first duty cycle adjustment module, configured to reduce an upper limit of a duty cycle of a PWM signal based on the duty cycle limit gradient, so as to limit a short-circuit current; A second gradient calculation module is used to determine a duty cycle release gradient based on the current current slope, current value and output end support capacitor voltage when it is monitored that the circuit breaker removes the short circuit fault; A second duty cycle adjustment module, configured to increase the duty cycle upper limit of the PWM signal based on the duty cycle release gradient, so as to limit the current passing through the DC output terminal of the energy storage and distribution system; Wherein, the first gradient calculation module includes: A first duty cycle limiting gradient determining unit, configured to use the product of the current current slope and the current slope coefficient as a first duty cycle limiting gradient; wherein the current slope coefficient is a negative value; A second duty cycle limiting gradient determining unit, configured to use the product of the current current value and the current value coefficient as a second duty cycle limiting gradient; wherein the current value coefficient is a negative value; a third duty cycle limiting gradient determining unit, configured to use the product of the difference between the current output end supporting capacitor voltage and the capacitor voltage lower limit value and the capacitor voltage coefficient as the third duty cycle limiting gradient; wherein the capacitor voltage coefficient is a negative value; a duty cycle limit gradient determining unit, configured to take the sum of the first duty cycle limit gradient, the second duty cycle limit gradient and the third duty cycle limit gradient as a current duty cycle limit gradient; Wherein, the second gradient calculation module includes: a first duty cycle release gradient determining unit, configured to determine a first duty cycle release gradient based on the current slope and a first duty cycle release coefficient; a second duty cycle release gradient determining unit, configured to determine a second duty cycle release gradient based on the current current value, the rated current and the second duty cycle release coefficient; a third duty cycle release gradient determining unit, configured to determine a third duty cycle release gradient based on a current output end support capacitor voltage, a capacitor rated voltage and a third duty cycle release coefficient; The duty cycle release gradient determining unit is used to take the sum of the first duty cycle release gradient, the second duty cycle release gradient and the third duty cycle release gradient as the current duty cycle release gradient.

8. An electronic device, characterized in that: include: Memory, used to store computer programs; A processor, configured to execute the computer program to implement the short circuit fault processing method according to any one of claims 1 to 6.

9. A computer-readable storage medium, characterized in that: Used to store a computer program; wherein, when the computer program is executed by a processor, the short-circuit fault processing method according to any one of claims 1 to 6 is implemented.

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