Short-circuit fault processing method, device, equipment and medium

Abstract

The invention discloses a short-circuit fault processing method and device, equipment and a medium, and relates to the field of energy storage and power distribution. If the short-circuit fault occurs, determining a duty ratio limit gradient based on a current slope, a current value and an output end support capacitor voltage; reducing the duty ratio upper limit of the PWM signal based on the duty ratio limit gradient so as to limit the short-circuit current; when it is monitored that the short circuit fault of the circuit breaker is removed, determining a duty ratio release gradient based on the current slope, the current value and the output end support capacitor voltage; and based on the duty ratio release gradient, increasing the duty ratio upper limit of the PWM signal so as to limit the current passing through the DC output end of the energy storage power distribution system. According to the invention, system stop caused by a short circuit phenomenon can be avoided, and the energy storage power distribution system can be rapidly and stably recovered to a normal working state after a fault is removed.

Description

Technical Field

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

[0002] In the energy storage and distribution system, bidirectional DC / DC power converters are used to realize energy exchange between batteries and the grid. However, since bidirectional DC / DC power converters often use PI (Proportional Integral) control strategy, their low damping characteristics will cause overcurrent 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 distribution system. However, when a short circuit fault is detected, the protection mechanism of the current limiter will be triggered quickly to cut off or limit the current. And after the fault is removed, its protection mechanism remains locked, so the system cannot resume normal working state after the point where the short circuit fault occurs is removed.

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

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

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

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

[0008] If the short circuit fault occurs, the duty cycle limiting gradient is determined based on the current current slope, current value and output end support capacitor voltage;

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

[0010] When it is detected 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;

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

[0012] Optionally, based on the current slope, current value and output terminal support capacitor voltage, a duty cycle limiting gradient is determined, including:

[0013] 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;

[0014] 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;

[0015] 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;

[0016] 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.

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

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

[0019] ;

[0020] 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;

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

[0022] ;

[0023] Among them, the For the second duty cycle release gradient, is the second duty cycle release coefficient, For the rated current, is the current value of the current;

[0024] Based on the current output end support capacitor voltage, capacitor rated voltage and third duty cycle release coefficient, the third duty cycle release gradient is determined, and the specific formula is as follows:

[0025] ;

[0026] 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 end supporting capacitor voltage;

[0027] 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.

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

[0029] 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;

[0030] 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;

[0031] 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.

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

[0033] 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;

[0034] 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.

[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 limiting gradient, reducing the duty cycle upper limit of the PWM signal to limit the short-circuit current includes:

[0037] 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.

[0038] In a second aspect, the present application provides a short circuit fault handling device, which is applied to an energy storage distribution system; wherein the energy storage distribution system includes a DC / DC power converter, including:

[0039] A fault judgment module is used to judge whether a short circuit fault occurs in the power grid;

[0040] 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;

[0041] 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;

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

[0043] The second duty cycle adjustment module is used to increase the duty cycle upper limit 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 and distribution system.

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

[0045] Memory, used to store computer programs;

[0046] The processor is used to execute the computer program to implement the above-mentioned short circuit fault processing method.

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

[0048] From the above, it can be concluded that in the energy storage distribution system, if a short circuit fault occurs, the current current slope, current value and output end support capacitor voltage can be used to continuously calculate the current duty cycle limit gradient, and at the same time, based on the 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 distribution system not to exceed the safety threshold. Therefore, when a short circuit fault occurs in the system, it can respond to the change of the system current in real time and respond quickly to avoid damage to the system components caused by overcurrent. In addition, while limiting the current at the DC output end of the energy storage distribution system, the short circuit fault will trigger the circuit breaker to trip, so that the fault point is removed. At this time, the current duty cycle release gradient is calculated through the current slope, current value and output end support capacitor voltage, and the PWM duty cycle can be gradually relaxed, so that the system can quickly and smoothly resume normal operation. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying creative work.

[0050] Figure 1 A flow chart of a short circuit fault processing method disclosed in this application;

[0051] Figure 2 A mode switching flow chart disclosed in this application;

[0052] Figure 3 This is a schematic diagram of the structure of a short-circuit fault processing device disclosed in this application;

[0053] Figure 4 This is a structural diagram of an electronic device disclosed in this application. DETAILED DESCRIPTION

[0054] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0055] In the energy storage and distribution system, bidirectional DC / DC power converters are used to realize energy exchange between batteries and the grid. However, since bidirectional DC / DC power converters often use PI (Proportional Integral) control strategy, their low damping characteristics will cause overcurrent 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 distribution system. However, when a short circuit fault is detected, the protection mechanism of the current limiter will be triggered quickly to cut off or limit the current. And after the fault is removed, its protection mechanism remains locked, so the system cannot resume normal working state after the point where the short circuit fault occurs is removed.

[0057] To this end, the present application provides a short-circuit fault processing solution to improve the response speed of the DC / DC power converter under a short-circuit fault, to avoid the occurrence of overcurrent, and to quickly and smoothly restore the normal working state after the fault is removed.

[0058] See also Figure 1 , 2 As shown, an embodiment of the present invention discloses a short circuit fault processing method, which is applied to an energy storage distribution system; wherein the energy storage distribution system includes a DC / DC power converter, and the method includes:

[0059] Step S11, determining whether a short circuit fault occurs in the power grid.

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

[0061] In this embodiment, a variety of methods can be used to determine whether a short circuit fault occurs in the power grid.

[0062] In the first specific implementation, the predicted current slope is obtained to determine whether the predicted current slope is greater than the limited slope boundary value; if greater, it is determined that a short circuit fault occurs in the power grid. It can be understood that the changes caused by normal switching of loads, start and stop of electrical equipment, etc. are usually gradual, and there will be no sudden and large changes. Therefore, when the power grid is operating normally, the current in the power grid is stable, changes more slowly over time, and its current slope is also small.

[0063] When a short circuit occurs in the power grid, the current will increase sharply. At the moment of short circuit, the current will quickly rise from the normal operating value to a short circuit current value far higher than the normal level. In this process, the rate of change of the current over time is very large, that is, the current slope shows a significant mutation. The current slope k n The specific formula is as follows:

[0064] ;

[0065] in, is the current difference between the current moment and the previous moment, For the current moment The current value at For the previous moment The current value.

[0066] ;

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

[0068] Furthermore, based on the current output end support capacitor voltage and the current current value, the predicted current slope is determined through the current slope prediction model; when the predicted current slope is greater than the limited slope boundary value, it is determined that a short circuit fault has occurred. In the early stage of a short circuit fault in the power grid, even before the current value of the power grid has reached the action threshold of the protection device, the predicted current slope at the next moment can be obtained through the current slope prediction model to determine whether a short circuit fault is about to occur, and abnormal changes in the current slope are detected, so that an early warning signal is issued in advance, which buys precious time for quickly removing the fault and protecting the safety of the equipment.

[0069] In this embodiment, the current slope prediction model is a linear regression model based on the historical current slope and its corresponding system state. The current data of the output terminal under different working conditions is sampled at high speed to use the historical current slope data. , ,……, And its corresponding working conditions, realize slope calculation and slope curve fitting, and the specific formula of the obtained linear regression model is as follows:

[0070] ;

[0071] in, For the next moment The predicted current slope, , , and are the coefficients of the linear regression model, For the current moment The input voltage, For the current moment of load current.

[0072] Understandably, , , and It can be determined by combining the simulation data of simulink and the actual experimental data under different working conditions, and the above-mentioned limited slope boundary value k th It needs to be set according to the rated operating data performance of the energy storage distribution system and the short-circuit withstand capability determined by the device selection. n+1 Greater than the limit slope boundary value When the short circuit fault occurs, it can be judged that the short circuit fault is about to occur, and the corresponding operation needs to be triggered to avoid the overcurrent phenomenon caused by the short circuit fault.

[0073] It should be noted that, on the one hand, obtaining an accurate predicted current slope requires high-precision real-time measurement of the current and fast and accurate calculation. This places high demands on the measuring equipment and data processing system. If the measurement accuracy is insufficient or the calculation error is large, it may lead to misjudgment or missed judgment. On the other hand, there are various interference factors in the power system, such as lightning strikes, the starting of large motors, the switching of capacitors, etc. These operations may cause instantaneous fluctuations or changes in the current, thereby 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 by predicting the current slope, multiple methods can also be set up simultaneously in the energy storage distribution system to make a comprehensive judgment on the working conditions of the system.

[0074] In a second specific implementation, the current current value is obtained to determine whether the current current value is greater than the short-circuit current limiting boundary value; if greater than, it is determined that a short-circuit fault occurs in the power grid. It is understandable that when a short-circuit fault occurs in the power grid, the impedance of the circuit will decrease sharply. When the power supply voltage remains basically unchanged, the reduction in impedance will inevitably lead to a sharp increase in current. Therefore, a large change in the current value is a significant 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, this abnormal change can be captured to determine whether a short circuit occurs in the power grid.

[0075] In the third specific implementation, the current output end support capacitor voltage is obtained to determine whether the current output end support capacitor voltage is less than the minimum capacitor voltage boundary value; if less than, it is determined that a short circuit fault occurs in the power grid. The support capacitor smoothes the voltage fluctuation by storing and releasing charge, ensures that the voltage output by the power grid remains within a relatively stable range, provides a stable power supply for various electrical equipment connected to the power grid, and maintains the output end voltage stability. It is understandable that when a short circuit fault occurs in the power grid, the impedance in the circuit will suddenly decrease, causing the current to increase sharply, causing the state of the circuit to suddenly change. At this time, the support capacitor will begin 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 discharge speed under normal circumstances, and the stored charge decreases rapidly, resulting in a rapid drop in the voltage across the support point capacitor. Therefore, by monitoring the output end support capacitor voltage and comparing the above output end support capacitor voltage with the minimum capacitor voltage boundary value, it can be determined whether the power grid has a short circuit fault.

[0076] It is understandable that in order to judge the short-circuit fault of the power grid, it is necessary to arrange multiple sensors at the key parts of the DC-DC power converter to monitor the voltage and current value of the output supporting capacitor in real time, and input the monitored data and the feedback of the power grid working status and load changes into the fuzzy logic controller in real time. Based on the acquired data and judging whether a short-circuit fault occurs in the power grid, or whether the short-circuit fault is successfully removed, it is further judged whether the energy storage distribution system needs to switch modes. Among them, the energy storage distribution system includes current limiting mode, fast recovery mode and steady-state mode. Through real-time evaluation of the system working conditions, it can smoothly switch between the three modes.

[0077] like Figure 2 As shown, the current and voltage values ​​of the system can be sampled at high speed by current sensors and voltage sensors, and the obtained high-speed sampling signals are processed and analyzed to determine whether a fault will occur at the next moment. If not, maintain normal operation, that is, steady-state mode. If so, the system needs to be switched to current limiting mode to limit the current within a safe range and protect the safety of the system. In addition, after monitoring that the DC circuit breaker trips within 500ms to remove the fault point, the current limiting mode can be switched to a fast recovery mode to quickly and smoothly restore the system to the rated state, 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 500ms, the system needs to perform a fault mode at this time to issue an alarm, and at the same time seal the switch tube, disconnect all circuit breakers and shut down to protect the safety of the system and personnel.

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

[0079] Step S12: If a short circuit fault occurs, the duty cycle limiting gradient is determined based on the current current slope, current value and output end support capacitor voltage.

[0080] In this embodiment, after a short circuit fault is detected in the power grid or a short circuit fault is predicted to occur in the power grid according to the above method, in order to avoid overcurrent, the energy storage distribution system needs to be converted to a current limiting mode to reduce the output current.

[0081] Furthermore, in order to ensure that the current value of the system does not exceed the safety threshold during a short-circuit fault by accurately controlling the current, the current slope, current value and output end support capacitor voltage of the power distribution system can be combined to determine the duty cycle limiting gradient. It should be noted that the duty cycle limiting gradient is mainly a parameter that limits the rate of duty cycle reduction, that is, the duty cycle limiting gradient specifies the maximum change amplitude of the duty cycle per unit time to ensure that the duty cycle changes smoothly, thereby making the current change relatively smooth and avoiding the impact of current mutations on the circuit. In a DC-DC power converter, the duty cycle limiting gradient can prevent the sudden increase in duty cycle from causing excessive output current, thereby protecting circuit components such as switches, inductors, and loads from the impact of excessive current.

[0082] In this embodiment, 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 specific formula is as follows:

[0083] ;

[0084] in, is the first duty cycle limiting gradient, is the current slope coefficient, is the current slope.

[0085] It should be noted that the current slope reflects the speed of current change. Therefore, if the current current slope is large, it means that the current short-circuit current is increasing rapidly, and the duty cycle needs to be adjusted more significantly to suppress the current rise. Therefore, the magnitude of the current slope is 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 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;

[0087] ;

[0088] in, is the second duty cycle limiting gradient, is the current value coefficient, The current value.

[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 to a safe range as soon as possible. Therefore, the current value is 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 end support 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;

[0091] ;

[0092] in, is the third duty cycle limiting gradient, is the capacitance voltage coefficient, is the lower limit of capacitor voltage, is the current output end support capacitor voltage.

[0093] It should be noted that since the lower support capacitor voltage indicates that the support capacitor is discharged more at this time, the system stability is more threatened. Therefore, 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] Further, the sum of the first duty cycle limiting gradient, the second duty cycle limiting gradient and the third duty cycle limiting gradient is used as the current duty cycle limiting gradient The specific formula is as follows:

[0095] ;

[0096] In addition, since the first duty cycle limiting gradient, the second duty cycle limiting gradient and the third duty cycle limiting gradient all reflect the magnitude of the duty cycle reduction, their corresponding coefficients are all negative numbers.

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

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

[0099] In this embodiment, Figure 2As shown, switch the PI parameters, based on the duty cycle limit gradient, reduce the duty cycle upper limit of the PWM signal to limit the short-circuit current. It can be understood that the proportional parameter determines the controller's response speed and adjustment strength to the error. Increasing the proportional parameter will make the controller more sensitive to the error, so that the duty cycle adjustment speed will be faster, and the output can be closer to the set value faster. The integral parameter is mainly used to eliminate the steady-state error of the system. During the duty cycle adjustment process, the integral link will accumulate the error, and gradually adjust the duty cycle over time so that the output reaches and stabilizes at the set value. Therefore, after entering the current limiting mode, adjusting the PI parameters to parameters that are more suitable for the current limiting mode can make the duty cycle quickly adjustable, and also make the PI control output the duty cycle in a restricted state to limit the DC output current.

[0100] Step S14: when it is detected that the circuit breaker clears the short circuit fault, the duty cycle release gradient is determined based on the current current slope, current value and output end support capacitor voltage.

[0101] In this embodiment, after a fault occurs in the power grid, the circuit breaker at the corresponding position will trip quickly to cut off the short circuit fault. At this time, the energy storage distribution system needs to be gradually restored to a normal working state, so the system needs to be converted to a fast recovery mode, and the current duty cycle release gradient is calculated based on the current current slope, current value and output end support capacitor voltage. It can be understood that, similar to the duty cycle limit gradient, the duty cycle release gradient is mainly a parameter that limits the rate of increase of the duty cycle, that is, the duty cycle release gradient specifies the maximum change amplitude of the duty cycle in a unit time to ensure that the duty cycle changes smoothly.

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

[0103] ;

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

[0105] It can be understood that as the current slope decreases, it indicates that the current current changes slowly, so the first duty cycle release gradient can be correspondingly increased to speed up the release of the duty cycle. As the current slope increases, it indicates that the current current changes quickly, so the first duty cycle release gradient can be correspondingly reduced to slow down the release of the duty cycle and avoid current shock.

[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, and the specific formula is as follows:

[0107] ;

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

[0109] It is understandable that as the current value approaches the rated current, the system is closer to normal working state. The rated current of the equipment is the maximum current value that can be operated stably for a long time. Therefore, when the current value gradually approaches the rated current, it means that the DC-DC power converter is capable of bearing a larger load. At this time, speeding up the release speed of the duty cycle limit can allow the DC-DC power converter to give full play to its power conversion capacity within a safe range and output more power to quickly restore the system to normal working state.

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

[0111] ;

[0112] in, is the third duty cycle release gradient, is the third duty cycle release coefficient, is the capacitor rated voltage, is the current output end supporting capacitor voltage;

[0113] It should be noted that as the output-end support capacitor voltage recovers and increases, the duty cycle limit can be more actively released. Because the output-end support capacitor has the ability to store charge, when the output-end support capacitor voltage increases, it means 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 enable the DC-DC power converter to output greater power, so as to quickly restore the energy storage distribution system to 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 taken as the current duty cycle release gradient. The specific formula is as follows:

[0115] ;

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

[0117] In this embodiment, based on the current output-end supporting capacitor voltage, current value and current slope, the duty cycle release gradient is adjusted in real time according to the above algorithm, and based on the duty cycle release gradient, the duty cycle upper limit of the PWM signal is quickly and smoothly increased, so that the voltage and current in the system gradually return to normal levels.

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

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

[0120] Accordingly, see Figure 3 As shown, the embodiment of the present application further provides a short circuit fault processing device, which is applied to an energy storage distribution system; wherein the energy storage distribution system includes a DC / DC power converter, which may include:

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

[0122] A first gradient calculation module 12, for determining a duty cycle limiting gradient based on a current current slope, current value and output end 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, so as to limit the short-circuit current;

[0124] A second gradient calculation module 14 is used to determine a duty cycle release gradient based on the current current slope, the current value and the output end support capacitor voltage when it is monitored that the circuit breaker removes the short circuit fault;

[0125] The second duty cycle adjustment module 15 is used to increase the duty cycle upper limit 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 and distribution system.

[0126] From the above, it can be concluded that in the energy storage distribution system, if a short circuit fault occurs, the duty cycle limit gradient at the current moment can be immediately calculated through the current current slope, current value and output end support capacitor voltage, and the upper limit of the PWM duty cycle can be adjusted based on the duty cycle limit gradient to accurately control the system current not to exceed the safety threshold. Therefore, when a short circuit fault occurs in the system, it can respond to the change of the system current in real time and respond quickly to avoid damage to the system components caused by overcurrent. In addition, while limiting the system current, the short circuit fault will trigger the circuit breaker to trip, so that the fault point is removed. At this time, the duty cycle release gradient at the current moment is calculated through the current slope, current value and output end support capacitor voltage, and the PWM duty cycle can be gradually relaxed, so that the system can quickly and smoothly resume normal operation.

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

[0128] 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;

[0129] 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;

[0130] 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 a third duty cycle limiting gradient; wherein the capacitor voltage coefficient is a negative value;

[0131] The duty cycle limit gradient determining unit is 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.

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

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

[0134] ;

[0135] Among them, the The first duty cycle release gradient is, is the first duty cycle release coefficient, is the current slope;

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

[0137] ;

[0138] 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;

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

[0140] ;

[0141] 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 end supporting capacitor voltage;

[0142] 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.

[0143] In some specific implementations, the fault judgment module 11 includes:

[0144] A first fault judgment unit is used to obtain a predicted current slope to determine whether the predicted current slope is greater than a limited slope boundary value; if greater, it is determined that a short circuit fault occurs in the power grid;

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

[0146] The third fault judgment unit is used to 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, it is determined that a short circuit fault occurs in the power grid.

[0147] In some specific embodiments, the first fault judgment unit determines the predicted current slope based on the current output end supporting capacitor voltage and the current current value through a current slope prediction model; when the predicted current slope is greater than the limited slope boundary value, it is determined that a short circuit fault has occurred.

[0148] The current slope prediction model is a linear regression model based on the historical current slope and its corresponding system state.

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

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

[0151] Furthermore, the present application also discloses an electronic device. Figure 4 This is a structural diagram of an electronic device disclosed in the present application, and the content in the diagram cannot 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. The memory 22 is used to store a computer program, which is loaded and executed by the processor 21 to implement the relevant steps in the short-circuit fault processing method disclosed in any of the aforementioned embodiments. In addition, 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 working voltage 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 the external device, and the communication protocol it follows is any communication protocol that can be applied to the technical solution of the present application, and is not specifically limited here; the input and output interface 25 is used to obtain external input data or output data to the outside world, and its specific interface type can be selected according to specific application needs and is not specifically limited here.

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

[0154] The operating system 221 is used to manage and control the hardware devices and computer program 222 on the electronic device 20, which can be Windows Server, Netware, Unix, Linux, etc. In addition to including a computer program that can be used to complete the short-circuit fault processing method performed by the electronic device 20 disclosed in any of the aforementioned embodiments, the computer program 222 can further include a computer program 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 the computer program, when executed by a processor, implements the short-circuit fault processing method disclosed above. The specific steps of the method can refer to the corresponding contents disclosed in the above embodiments, and will not be repeated here.

[0156] In this specification, each embodiment is described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the embodiments can be referred 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 the relevant parts can be referred to the method part.

[0157] Professionals may further appreciate that the units and algorithm steps of each example described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, computer software, or a combination of the two. In order to clearly illustrate the interchangeability of hardware and software, the composition and steps of each example have been generally described in the above description according to function. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Professionals and technicians may use different methods to implement the described functions for each specific application, but such implementation should not be considered to be beyond the scope of this application.

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

[0159] Finally, it should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the sentence "comprise a ..." do not exclude the presence of other identical elements in the process, method, article or device including the elements.

[0160] The technical solution provided by the present application is introduced in detail above. Specific examples are used in this article to illustrate the principles and implementation methods of the present application. The description of the above embodiments is only used to help understand the method of the present application and its core idea. At the same time, for general technicians in this field, according to the idea of ​​the present application, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as a limitation on the present 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, the duty cycle limiting gradient is determined based on the current current slope, current value and output end support capacitor voltage; 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 detected 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; Based on the duty cycle release gradient, the duty cycle upper limit of the PWM signal is increased to limit the current passing through the DC output terminal of the energy storage and distribution system.

2. The short circuit fault processing method according to claim 1, characterized in that: Based on the current slope, current value and output end support capacitor voltage, the duty cycle limit 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; 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.

3. The short circuit fault processing method according to claim 1, characterized in that: Based on the current slope, current value and output end support capacitor voltage, a duty cycle release gradient is determined, including: Based on the current current slope and the first duty cycle release coefficient, the first duty cycle release gradient is determined, and the specific formula 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; Based on the current current value, the rated current and the second duty cycle release coefficient, the second duty cycle release gradient is determined, and the specific formula is as follows: ； Among them, the For the second duty cycle release gradient, is the second duty cycle release coefficient, For the rated current, is the current value of the current; Based on the current output end support capacitor voltage, capacitor rated voltage and third duty cycle release coefficient, the third duty cycle release gradient is determined, and the specific formula 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 end supporting capacitor voltage; 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.

4. 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.

5. The short circuit fault processing method according to claim 4, 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.

6. The short circuit fault processing method according to claim 5, 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.

7. The short circuit fault processing method according to any one of claims 1 to 6, 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.

8. 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; The second duty cycle adjustment module is used to increase the duty cycle upper limit 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 and distribution system.

9. 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 7.

10. 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 7 is implemented.

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