Impulse power transmission cable short circuit fault analysis method and system

Abstract

This invention discloses a method and system for analyzing short-circuit faults in pulse power transmission cables. The method includes fault current analysis of the power supply circuit and the load circuit, used to study the impact of short-circuit faults in the transmission cable during the discharge process of the pulse power supply. The method includes the following steps: acquiring circuit component parameters and output current waveforms; calculating the fault current in the power supply circuit and the load circuit, using the short-circuit location as a boundary; in the power supply circuit, the cable short circuit reduces the circuit inductance and increases the peak current; in the load circuit, impedance changes cause load polarity reversal, prematurely triggering the diodes in subsequent modules, leading to their damage during reverse recovery; based on the above analysis, a short-circuit protection scheme is proposed by increasing component design parameter redundancy and impedance matching. This invention, through the analysis method of establishing a short-circuit fault model for pulse power transmission cables, can effectively analyze the impact of cable short circuits on the system and proposes a practical and feasible protection scheme.

Description

Technical Field

[0001] This invention belongs to the field of cable electrical fault simulation analysis, specifically involving an analysis method for establishing a short-circuit model of a pulse power transmission cable. Background Technology

[0002] Pulse power supply systems have numerous modules and complex structures, requiring extremely high safety and reliability. A short circuit in the circuit will jeopardize the normal operation of the system.

[0003] Currently, in the field of power electronics, the analysis of short-circuit problems mainly focuses on alternating current, such as single-phase ground faults and two-phase inter-electrode short circuits. Research on DC current cable short-circuit problems during transient discharge of pulsed power supplies is very limited. Therefore, to conduct fault analysis of pulsed power supplies and provide a reference for device optimization, it is necessary to study the impact of cable short circuits from a theoretical perspective and establish a method for short-circuit analysis models of transmission cables. Summary of the Invention

[0004] This invention addresses the short-circuit problem in transmission cables during current pulse power supply experiments by providing a method and system for analyzing short-circuit faults in pulse power supply transmission cables.

[0005] To achieve the above objectives, the present invention provides the following technical solution: a method for analyzing short-circuit faults in pulse power transmission cables, comprising the following steps:

[0006] Collect circuit component data, detect pulse power supply discharge current, and preprocess the current signal;

[0007] Analyze the impact of short circuits in transmission cables on the power supply module and load module;

[0008] The power supply module and load module are protected after a short circuit fault occurs in the cable.

[0009] A short-circuit fault analysis system for pulse power transmission cables, comprising:

[0010] The information acquisition module is used to acquire circuit component data, detect pulse power supply discharge current, and preprocess the current signal;

[0011] The fault analysis module is used to analyze the impact of short circuits in the transmission cable on the power supply module and the load module.

[0012] The fault protection module is used to protect the power supply module and load module after a short circuit fault occurs in the cable.

[0013] An electronic device includes a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the program to implement the above-described pulse power transmission cable short-circuit fault analysis method.

[0014] A computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the above-described method for analyzing short-circuit faults in pulse power transmission cables.

[0015] Compared with existing technologies, the significant advantages of this invention are: 1) By using simulation software to establish a short-circuit fault model, various fault problems that occur and do not occur in the experiment can be accurately simulated. Without consuming experimental equipment, the impact of the fault can be accurately determined, greatly avoiding resource waste; 2) When establishing the fault model, only circuit component parameters and current data need to be collected, and the power supply module and load module are studied separately. By substituting them into the simulation software, the impact of the short-circuit fault on the circuit can be determined, requiring less data; 3) By analyzing the established fault model, the severity of the fault under different initial conditions can be obtained by changing the parameters, which is flexible, convenient, and more operable; 4) The method is simple, effective, reliable, and easy to implement.

[0016] The present invention will now be described in further detail with reference to the accompanying drawings. Attached Figure Description

[0017] Figure 1 This is a schematic diagram illustrating the process of a short-circuit analysis model for pulse power transmission cables.

[0018] Figure 2 This is the first-stage circuit for discharging the power module during a short circuit.

[0019] Figure 3 This is the second-stage circuit for discharging the power module during a short circuit.

[0020] Figure 4 This is a schematic diagram of a short-circuit model for a pulse power transmission cable. Detailed Implementation

[0021] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0022] In the problem of short circuit in transmission cables, combined with Figure 1 A method for short-circuit analysis model of transmission cables is provided, which includes the following steps:

[0023] Information acquisition: Acquire circuit component data, detect pulse power supply discharge current, and preprocess the current signal;

[0024] Fault Analysis: The impact of short circuits in the transmission cable on the power supply module and load module is analyzed. The main research object is current information, and the study is conducted in two parts of the circuit.

[0025] Fault protection: After a short circuit fault occurs in the cable, targeted protection methods are taken for the power supply module and load module to ensure the safe operation of the system.

[0026] In a further embodiment, in the schematic diagram of the method for establishing a short-circuit analysis model of a transmission cable, the information acquisition module includes:

[0027] According to the component design specification, test its internal resistance and internal inductance at power frequency, and establish a pulse power supply discharge circuit model during normal operation.

[0028] The current sensor is mounted on the transmission cable, and the cable passes through the sensor coil in a loop manner. The sensor is not directly connected to the circuit, which avoids electromagnetic interference. It has high measurement accuracy and is suitable for detecting the discharge current of power modules.

[0029] For ease of understanding, the Rogowski coil of the current sensor is explained as follows: the discharge current flows through the center of the sensor coil. According to the law of magnetic induction and Ampere's circuital law, the output signal of the transmitter is the differential of the current with respect to time, di / dt.

[0030] By integrating the output voltage signal of the current transmitter through an integrating circuit, a current quantity can be obtained. This current quantity is proportional to the input current, and thus the original current can be determined.

[0031] In a further embodiment, the fault analysis includes:

[0032] When the transmission cable is short-circuited, it is divided into two parts: the power circuit and the load circuit, with the short-circuit location as the boundary.

[0033] For the power module after a short circuit, Kirchhoff's voltage theorem analysis method is adopted. Based on the characteristics of the energy storage capacitor and inductor, the fault current solution process is divided into two stages, the specific process of which includes:

[0034] Combination Figure 2 When the energy storage capacitor discharges, the circuit can be considered to contain only three components: capacitor, inductor, and resistor, and is equivalent to a second-order RLC circuit. The circuit equation is as follows:

[0035] u c +u L +u R =0

[0036] u c u L u R These are the capacitor voltage, inductor voltage, and resistor voltage, respectively. The capacitor current i is known. C and inductor voltage u L They respectively satisfy the following relations:

[0037]

[0038] In the first stage of discharge, the capacitor current i C Equal to inductor current i L Therefore, substituting both into the circuit equations yields:

[0039]

[0040] Where C is the discharge capacitor, and L and R are the circuit's equivalent resistance and inductance;

[0041] According to the solution method of the second-order ordinary differential coefficient equation, the pulse power supply system satisfies Due to this relationship, the power module circuit operates in an underdamped oscillatory discharge mode. The solution to the circuit's differential equation after a cable short-circuit fault is a pair of conjugate complex roots, denoted as...

[0042]

[0043]

[0044] In the formula, σ and ω are the real and imaginary parts of the conjugate complex root, respectively. Let ω0 and θ be:

[0045]

[0046] Let the initial voltage across the discharge capacitor be U0. From this, the voltage U across the capacitor can be calculated. c and short-circuit fault current i f The expression is:

[0047]

[0048] When a short circuit occurs in the power module circuit, the capacitor undergoes underdamped oscillating discharge, and the fault current i f A sharp rise occurs when the voltage U across the capacitor increases. c When it crosses zero, it means the capacitor has finished discharging;

[0049] Combination Figure 3 According to the characteristics of thyristors, when the current flowing through the thyristor is less than the conduction current, the thyristor will automatically turn off. Entering the second stage of discharge, the tuning inductor continues to release the stored energy through the freewheeling circuit, and the diode conducts. The circuit can be equivalent to a first-order RL circuit model, and the KVL equations can be derived:

[0050] u L +u R =0

[0051]

[0052] In the formula, R1 and L1 are the equivalent resistance and equivalent inductance of the circuit. It is known that the inductor current cannot change abruptly, so the current remains constant at the instant of switching from the RLC circuit to the RL circuit. The initial value of the current in the RL circuit is denoted as I1. After the diode is turned on, the discharge current decays exponentially with R1 / L1 as the time constant.

[0053] Fault current i at the power supply terminal f The maximum fault current is reached during the first stage of discharge. After differentiating the current and setting the rate of change of current di / dt to zero, the time t of the maximum fault current can be obtained. m and amplitude i fmax for

[0054]

[0055]

[0056] Therefore, the peak fault current i fmax It is mainly determined by the initial voltage and the loop inductance. When a short circuit fault occurs in the transmission cable, the stray inductance of the cable decreases, resulting in an increase in the peak current.

[0057] In further case analysis, the following analysis method is adopted for load modules after short circuit, and the specific steps are as follows:

[0058] Combination Figure 4 Based on Kirchhoff's voltage theorem, the formulas for calculating the load current and voltage are derived:

[0059]

[0060]

[0061] In the formula, R2 = R L +R cab2 L2 = L L +L cab2 I2 is the initial current of the circuit, L cab2 and R cab2 L represents the inductance and resistance of the cable on the load side. L and R L The load is resistive and inductive. The current i f Substitute the load voltage U L The calculation formula is further used to obtain the load voltage as follows:

[0062]

[0063] Therefore, when a short circuit fault occurs in the transmission cable, the parameters of the circuit originally connected to the load change drastically, and the load voltage U... L The sign of R depends on the relationship between the remaining cable inductance and the load inductance, i.e., the expression R.L L cab -L L R cab Positive and negative, if the relationship between them satisfies the following conditions:

[0064]

[0065] Then the load voltage U L A value less than 0 indicates a reversal of the load's polarity. Since the potentials are equal, the load has a negative voltage U. L This will cause the freewheeling diode of the subsequent module to turn on prematurely. When a reverse voltage is applied, the diode will return to the cutoff state. During this reverse recovery process, if the dv / dt of the diode is too large, it will break down.

[0066] In a further embodiment, in the schematic diagram of the method for establishing a short-circuit analysis model of a transmission cable, the fault protection method includes the following steps:

[0067] To address the impact of short-circuit current in the power module, a model of cable short-circuit conditions is established. When the capacitor voltage is set to the maximum energy storage voltage, the short-circuit current during a cable short-circuit fault will exceed the normal current by a significant margin compared to the peak current of power supply discharge under normal conditions. Therefore, when selecting and designing pulse power supply components, redundant parameters should be added. The cable short-circuit current can be used as a reference to ensure that components such as thyristors, diodes, and inductors in the circuit can withstand a certain range of extreme fault currents.

[0068] To address situations where changes in circuit parameters lead to changes in load voltage, a protection method can be implemented using an inductive discrimination approach. For cable and load parameters, the load voltage polarity will not change when the following conditions are met, thus avoiding damage to the diodes in subsequent modules.

[0069]

[0070] This invention proposes an analysis method for short-circuit faults in pulse power transmission cables. By establishing simulation models and conducting theoretical calculations, the impact of cable short-circuit faults can be quantitatively analyzed. Furthermore, by flexibly adjusting model parameters, the specific degree of impact of short-circuit faults under different initial conditions can be obtained. Based on this, practical circuit optimization and protection schemes are proposed, which greatly reduces damage to pulse power supply circuit components and fully improves the utilization rate of experimental resources.

[0071] This invention also provides an analysis system for short-circuit faults in pulse power transmission cables, comprising:

[0072] Information acquisition module: used to acquire circuit component data, detect pulse power supply discharge current, and preprocess the current signal;

[0073] Fault Analysis Module: Used to analyze the impact of short circuits in transmission cables on the power supply module and load module. The main research object is current information, and the study is conducted in two parts of the circuit.

[0074] Fault protection module: Used to take targeted protection measures for the power supply module and load module after a short circuit fault occurs in the cable, so as to ensure the safe operation of the system.

[0075] For details on the implementation of the above module functions, please refer to the description of the analysis method for short circuit faults in pulse power transmission cables above, which will not be repeated here.

[0076] In summary, this invention analyzes short-circuit faults in pulse power transmission cables. By collecting data, establishing fault models, analyzing discharge circuits, and performing simulation calculations, it can determine the impact of cable short circuits on system operation and provide short-circuit protection schemes, thereby improving the operational reliability and safety of pulse power systems. This invention is effective and feasible.

[0077] The above description details the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for analyzing short-circuit faults in pulse power transmission cables, characterized in that, Includes the following steps: Collect circuit component data, detect pulse power supply discharge current, and preprocess the current signal; The impact of a short circuit in the transmission cable on the power module and load module is analyzed as follows: (1) When the transmission cable is short-circuited, it is divided into two parts: the power supply circuit and the load circuit, with the short-circuit location as the boundary. (2) For the power module after a short circuit, Kirchhoff's voltage theorem analysis method is adopted. Based on the characteristics of the energy storage capacitor and inductor, the fault current solution process is divided into two stages, the specific process of which includes: When the energy storage capacitor discharges, the circuit can be considered to contain only three components: capacitor, inductor, and resistor, and is equivalent to a second-order RLC circuit. The circuit equations are as follows: in c +in L +in R =0 u c u L u R These are the capacitor voltage, inductor voltage, and resistor voltage, respectively. The capacitor current i is known. C and inductor voltage u L They respectively satisfy the following relations: In the first stage of discharge, the capacitor current i C Equal to inductor current i L Therefore, substituting both into the circuit equations yields: Where C is the discharge capacitor, and L and R are the circuit's equivalent resistance and inductance; According to the solution method of the second-order ordinary differential coefficient equation, the pulse power supply system satisfies Due to this relationship, the power module circuit operates in an underdamped oscillatory discharge mode. The solution to the circuit's differential equation after a cable short-circuit fault is a pair of conjugate complex roots, denoted as... In the formula, σ and ω are the real and imaginary parts of the conjugate complex root, respectively. Let ω0 and θ be: Let the initial voltage across the discharge capacitor be U0, from which the voltage U across the capacitor can be calculated. c and short-circuit fault current i f The expression is: When a short circuit occurs in the power module circuit, the capacitor undergoes underdamped oscillating discharge, and the fault current i f A sharp rise occurs when the voltage U across the capacitor increases. c When it crosses zero, it means the capacitor has finished discharging; Based on the characteristics of thyristors, when the current flowing through the thyristor is less than the conduction current, the thyristor will automatically turn off; entering the second stage of discharge, the tuning inductor continues to release the stored energy through the freewheeling circuit, the diode conducts, and the circuit is equivalent to a first-order RL circuit model, and the KVL equations are listed: in L +in R =0 In the formula, R1 and L1 are the equivalent resistance and equivalent inductance of the circuit. It is known that the inductor current cannot change abruptly, so the current remains unchanged at the instant of switching from the RLC circuit to the RL circuit. The initial value of the current in the RL circuit is denoted as I1. When the diode is turned on, the discharge current decays exponentially with R1 / L1 as the time constant. Fault current i at the power supply terminal f The maximum fault current is reached during the first stage of discharge. After differentiating the current and setting the rate of change of current di / dt to zero, the time t of the maximum fault current can be obtained. m and amplitude i fmax for For load modules that have been short-circuited, the following analysis method is adopted, and the specific steps are as follows: Based on Kirchhoff's voltage theorem, the load terminal current i is obtained. f and voltage U L The formula for calculation is: In the formula, R2 = R L +R cab2 L2 = L L +L cab2 I2 is the initial current of the circuit, L cab2 and R cab2 L represents the inductance and resistance of the cable on the load side. L and R L For load resistance and inductance; the current i f Substitute the load voltage U L The calculation formula is further used to obtain the load voltage as follows: Load voltage U L The sign of R depends on the relationship between the remaining cable inductance and the load inductance, i.e., the expression R. L L cab -L L R cab Positive and negative, if the relationship between them satisfies the following conditions: Then the load voltage U L A value less than 0 indicates a reversal of the load's polarity; since the potentials are equal, the load has a negative voltage U. L This will cause the freewheeling diode of the subsequent module to turn on prematurely. When a reverse voltage is applied, the diode will return to the cutoff state. During this reverse recovery process, if the dv / dt of the diode is too large, it will break down. The power supply module and load module are protected after a short circuit fault occurs in the cable.

2. The method for analyzing short-circuit faults in pulse power transmission cables according to claim 1, characterized in that, The data acquisition circuit components are used to detect the discharge current of the pulse power supply and to preprocess the current signal, as follows: Based on the circuit component design specifications, test its internal resistance and internal inductance at power frequency, and establish a pulse power supply discharge circuit model during normal operation. The current sensor is mounted on the transmission cable, and the cable is passed through the sensor coil in a loop manner; By integrating the output voltage signal of the current transmitter through the integrator circuit, a current quantity is obtained. This current quantity is proportional to the input current, and thus the original current can be known.

3. The method for analyzing short-circuit faults in pulse power transmission cables according to claim 2, characterized in that, The discharge current flows through the center of the sensor coil. According to the law of magnetic induction and Ampere's circuital law, the output signal of the transmitter is the differential of the current with respect to time, di / dt.

4. The method for analyzing short-circuit faults in pulse power transmission cables according to claim 1, characterized in that, After a short circuit fault occurs in the cable, targeted protection methods are implemented for the power supply module and the load module, including: (1) In view of the impact of the short circuit current of the power module, a model of the cable short circuit condition is established. When selecting and designing pulse power supply components, redundant parameters are added. The cable short circuit condition current is used as a reference to ensure that the thyristors, diodes and inductors in the circuit can withstand a certain range of extreme fault currents. (2) For load circuit protection schemes, when load voltage changes due to changes in circuit parameters, a protection method is adopted using a resistance-inductance discrimination method. This method applies to cable and load parameters when the following conditions are met: The load voltage polarity will not change, thus avoiding damage to the diodes in subsequent modules.

5. A short-circuit fault analysis system for pulse power transmission cables, characterized in that, include The information acquisition module is used to acquire circuit component data, detect pulse power supply discharge current, and preprocess the current signal; The fault analysis module is used to analyze the impact of short circuits in the transmission cable on the power supply module and the load module, as detailed below: (1) When the transmission cable is short-circuited, it is divided into two parts: the power supply circuit and the load circuit, with the short-circuit location as the boundary. (2) For the power module after a short circuit, Kirchhoff's voltage theorem analysis method is adopted. Based on the characteristics of the energy storage capacitor and inductor, the fault current solution process is divided into two stages, the specific process of which includes: When the energy storage capacitor discharges, the circuit can be considered to contain only three components: capacitor, inductor, and resistor, and is equivalent to a second-order RLC circuit. The circuit equations are as follows: in c +in L +in R =0 u c u L u R These are the capacitor voltage, inductor voltage, and resistor voltage, respectively. The capacitor current i is known. C and inductor voltage u L They respectively satisfy the following relations: In the first stage of discharge, the capacitor current i C Equal to inductor current i L Therefore, substituting both into the circuit equations yields: Where C is the discharge capacitor, and L and R are the circuit's equivalent resistance and inductance; According to the solution method of the second-order ordinary differential coefficient equation, the pulse power supply system satisfies Due to this relationship, the power module circuit operates in an underdamped oscillatory discharge mode. The solution to the circuit's differential equation after a cable short-circuit fault is a pair of conjugate complex roots, denoted as... In the formula, σ and ω are the real and imaginary parts of the conjugate complex root, respectively. Let ω0 and θ be: Let the initial voltage across the discharge capacitor be U0, from which the voltage U across the capacitor can be calculated. c and short-circuit fault current i f The expression is: When a short circuit occurs in the power module circuit, the capacitor undergoes underdamped oscillating discharge, and the fault current i f A sharp rise occurs when the voltage U across the capacitor increases. c When it crosses zero, it means the capacitor has finished discharging; Based on the characteristics of thyristors, when the current flowing through the thyristor is less than the conduction current, the thyristor will automatically turn off; entering the second stage of discharge, the tuning inductor continues to release the stored energy through the freewheeling circuit, the diode conducts, and the circuit is equivalent to a first-order RL circuit model, and the KVL equations are listed: in L +in R =0 In the formula, R1 and L1 are the equivalent resistance and equivalent inductance of the circuit. It is known that the inductor current cannot change abruptly, so the current remains unchanged at the instant of switching from the RLC circuit to the RL circuit. The initial value of the current in the RL circuit is denoted as I1. When the diode is turned on, the discharge current decays exponentially with R1 / L1 as the time constant. Fault current i at the power supply terminal f The discharge reaches its maximum value in the first stage. After differentiating the current and setting the rate of change of current di / dt to zero, the time t of the maximum fault current can be obtained. m and amplitude i fmax for For load modules that have been short-circuited, the following analysis method is adopted, and the specific steps are as follows: Based on Kirchhoff's voltage theorem, the load terminal current i is obtained. f and voltage U L The formula for calculation is: In the formula, R2 = R L +R cab2 L2 = L L +L cab2 I2 is the initial current of the circuit, L cab2 and R cab2 L represents the inductance and resistance of the cable on the load side. L and R L For load resistance and inductance; the current i f Substitute the load voltage U L The calculation formula is further used to obtain the load voltage as follows: Load voltage U L The sign of R depends on the relationship between the remaining cable inductance and the load inductance, i.e., the expression R. L L cab -L L R cab Positive and negative, if the relationship between them satisfies the following conditions: Then the load voltage U L A value less than 0 indicates a reversal of the load's polarity; since the potentials are equal, the load has a negative voltage U. L This will cause the freewheeling diode of the subsequent module to turn on prematurely. When a reverse voltage is applied, the diode will return to the cutoff state. During this reverse recovery process, if the dv / dt of the diode is too large, it will break down. The fault protection module is used to protect the power supply module and load module after a short circuit fault occurs in the cable.

6. The pulse power transmission cable short-circuit fault analysis system according to claim 5, characterized in that, The information acquisition module is used to collect circuit component data, detect the pulse power supply discharge current, and preprocess the current signal, as follows: According to the circuit component design specifications, test its internal resistance and internal inductance at power frequency, and establish a pulse power supply discharge circuit model during normal operation. The current sensor is mounted on the transmission cable, and the cable is passed through the sensor coil in a loop manner; By integrating the output voltage signal of the current transmitter through the integrator circuit, a current quantity is obtained. This current quantity is proportional to the input current, and thus the original current can be known.

7. An electronic device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that, When the processor executes the program, it implements the pulse power transmission cable short-circuit fault analysis method as described in any one of claims 1-4.

8. A computer-readable storage medium having a computer program stored thereon, characterized in that, When executed by the processor, the program implements the pulse power transmission cable short-circuit fault analysis method as described in any one of claims 1-4.

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