A method for setting fuses on shipboard DC distribution boards taking into account arc breaking

Abstract

The present invention provides a fuse setting method for a ship's DC distribution board that takes arcing into account. A fuse breaking arcing model is established: the fuse arcing process is described based on the Cassie arc model. The model parameter variation pattern is established by fitting test data using a genetic algorithm. A BP neural network is used to construct the relationship between the test loop resistance value and the arc voltage constant and arc time constant. The equivalent short-circuit impedance of the fault branch is calculated, and based on the proportional relationship between the short-circuit current peaks of the system and the test loop, the test loop impedance parameters that can be equivalent to the system short-circuit fault current waveform are calculated. Constraint-driven fuse setting is performed: with the constraints that the fuse rated current is not less than the product of the safety margin factor and the branch's maximum continuous operating current, and that the total joule integral value of the non-fault branch does not exceed 50% of its pre-arcing joule integral value, a minimum pre-arcing joule integral value priority strategy is adopted. Iterative selection begins with the smallest branch group and expands to all system branches.

Description

Technical Field

[0001] The invention belongs to the technical field of ship power system protection, and in particular relates to a ship DC distribution board fuse setting method taking arc breaking into consideration. Background Art

[0002] With the advancement of carbon neutrality in the maritime sector, shipboard DC integrated power systems (IPS) present enormous potential and opportunities for the transformation and upgrading of green shipping. However, they also face numerous challenges, with short-circuit fault protection being a key research topic. In a low-impedance DC IPS, the high-amplitude short-circuit current can significantly impact fragile power electronic components such as IGBTs and diodes. If the faulty branch is not promptly disconnected, the ship could suffer power outages, loss of control, or even fire.

[0003] In DC IPS, fast-acting, high-speed fuses are often used as fuses. When a short circuit occurs in the system, the fuse's internal fuse element melts, interrupting the fault current and clearing the faulty branch. However, whether the fuse in the non-faulty branch opens is closely related to the short-circuit location and the arcing process of the faulty branch fuse. Therefore, properly setting the fuses in each branch of the DC IPS to quickly clear the short circuit while meeting the requirements of selective protection is key to ensuring safe ship operation.

[0004] Currently, fuse setting in DC IPS primarily relies on methods such as comparing the melting moments of each branch fuse and comparing the intersection of branch current waveforms with the fuse's time-current characteristic curve. The implementation of these methods relies on current calculations throughout the DC IPS short-circuit protection process. DC IPS short-circuit current calculations are based on equivalent models of components such as fuses and cables. Whether the fuse model accurately represents the fuse's physical properties directly impacts the accuracy of the DC IPS short-circuit current calculations. The paper "Calculation and Analysis of Arc Characteristics of High-Voltage Current-Limiting Fuses Based on a Semi-Empirical Model" analyzes the arcing mechanism of high-voltage current-limiting fuses and establishes a semi-empirical arcing calculation model. However, it does not consider parameter selection issues associated with changes in fuse specifications. The paper "Modeling of Fuses for Melting Time and Fusing Current Analysis" constructs a fuse model that calculates fuse melting time and short-circuit current based on the Joule integral value. The paper "Simulation Research on Fuses in Ship DC Distribution Systems Based on the Mayr Arc Model" constructs a Mayr arc model fuse model in Simulink based on the principles of the Mayr arc model, but only models a single fuse. The paper "Animproved Mayr-type arc model based on current-zero measurements" improves the power dissipation coefficient of the Mayr arc model, dynamically adjusting model parameters according to the voltage or current during the arcing process to simulate the arcing process of a high-voltage circuit breaker. By combining the fuse breaking characteristic model with the DC IPS model, it is possible to determine whether the DC IPS protection scheme meets the requirements of selectivity. The paper "Design and Verification of Selective Protection for DC Networked Electric Propulsion Systems" models fuses as a series circuit of a variable resistor and inductor, analyzes the Joule integral values ​​of each branch fuse at different short-circuit points in the DC IPS, and analyzes the coordination of short-circuit protection based on the pre-arcing Joule integral value of the fuse. However, it does not clarify how to select fuses. The paper "Calculation of Short-Circuit Current and Analysis of Fuse Selective Protection in Marine DC Power Distribution Systems" established a DC IPS short-circuit current calculation model, calculated the Joule integral value of the fuse during the short-circuit process, and determined whether the fuse was disconnected based on the melting Joule integral value, thereby analyzing the selectivity of short-circuit fault protection. However, it ignored the impact of the fuse arcing process on the short-circuit current.

[0005] In summary, current fuse models have not yet been integrated with DC IPS short-circuit protection setting. Furthermore, existing DCIPS fuse setting methods primarily focus on coordinating the melting moments of each branch fuse, ignoring the increase in the Joule integral value of the non-fault branch caused by arcing of the fault branch fuse. According to the "Guidelines for Inspection of Shipboard DC Integrated Power Systems" published by the China Classification Society, DC IPS short-circuit protection has detailed regulations for the operation and Joule integral value of faulty and non-faulty fuses, and further selection schemes are urgently needed. Summary of the Invention

[0006] In response to the defects and shortcomings of the existing technology, the present invention provides a fuse setting method for a ship's DC distribution board that takes into account the breaking arc. The arcing process of the fuse is described based on the Cassie arc model. The model parameter variation law is established by fitting the test data through a genetic algorithm. The relationship between the test circuit resistance value and the arc voltage constant and arc time constant is constructed for the first time using a BP neural network. A system short-circuit process-test circuit mapping mechanism is proposed. Based on the equivalent short-circuit impedance of the fault branch, according to the proportional relationship between the short-circuit current peak values ​​of the system and the test circuit, the test circuit impedance parameters that can be equivalent to the system short-circuit fault current waveform are calculated to match the actual short-circuit current characteristics. An innovative constraint-driven iterative selection strategy is adopted. With the rated current safety margin and the Joule integral value of the non-fault branch not exceeding 50% of the pre-arc value as constraints, starting from the minimum pre-arc Joule integral value model, it is gradually expanded to the entire system through the minimum branch group to achieve a balance between the selectivity and rapidity of short-circuit protection. Experimental verification: After setting, the fault branch protection time is as low as about 7 milliseconds, and the risk of false operation of the non-fault branch is significantly reduced.

[0007] The solutions adopted by the present invention to solve the technical problems specifically include:

[0008] A method for setting fuses on shipboard DC distribution boards taking into account arc breaking:

[0009] Establishment of fuse breaking arcing model: The fuse breaking arcing process is described based on the Cassie arc model. The model parameter variation law is established by fitting the test data through genetic algorithm. The relationship between the impedance of the RLC series test circuit and the arc time constant and arc voltage constant of the Cassie arc model is constructed through BP neural network.

[0010] Map the short-circuit characteristics of the ship's DC integrated power system to the test circuit: Calculate the test circuit impedance parameters that can be equivalent to the system short-circuit fault current waveform based on the equivalent short-circuit impedance of the system fault branch, the ratio of the test circuit current peak to the short-circuit current peak;

[0011] Execute constraint-driven fuse setting: with the constraints that the rated current of the fuse is not less than the product of the safety margin factor and the maximum continuous operating current of the branch, and the total joule integral value of the non-fault branch does not exceed 50% of its pre-arcing joule integral value, adopt the minimum pre-arcing joule integral value priority strategy, start iterative selection from the smallest branch group and expand to the branches of the entire system.

[0012] Furthermore, the establishment of the model parameter change law includes: pre-charging a fixed capacitor voltage in the RLC series test circuit, minimizing the standard deviation of the test current waveform and the Cassie model output waveform through a genetic algorithm, obtaining multiple sets of RLC series test circuit resistance values, arc time constants, and arc voltage constant data sets, and obtaining the laws of resistance value and arc time parameters, and resistance value and arc voltage constant through a BP neural network.

[0013] Furthermore, the calculation of the equivalent short-circuit impedance of the fault branch is achieved by using the Thevenin equivalent principle.

[0014] Furthermore, calculating the test loop impedance parameters includes: calculating the inductance of the test loop based on the initial change rate of the short-circuit current of the ship's DC integrated power system branch; estimating the resistance value of the test loop according to the inductance of the test loop, the preset capacitance and the calculated equivalent short-circuit impedance of the fault branch, and then obtaining the test loop short-circuit current peak value; and then adjusting the test loop resistance value according to the deviation between the test loop short-circuit current peak value and the system branch short-circuit current peak value, the adjusted test loop resistance value = (test loop short-circuit current peak value / system short-circuit current peak value) × original test loop resistance value.

[0015] Furthermore, the iterative selection includes:

[0016] Branch fuse selection: Sort the candidate model library in ascending order by pre-arcing Joule integral value, build the initial branch group starting with the model with the smallest pre-arcing Joule integral value, further determine whether the branch group meets the constraints, and update the fuse models of branches that do not meet the constraints until all branch fuse models meet the constraints;

[0017] Main bus tie fuse selection: Collaborate with branch fuses to verify constraints. If no feasible solution exists, update the branch fuse model and reselect.

[0018] Furthermore, the fuse adopts a segmented equivalent model:

[0019] The on-state equivalent resistance is determined by the ratio of the rated power loss to the square of the rated current;

[0020] When the accumulated joule integral value of the fuse exceeds the pre-arcing joule integral value, it switches to the arcing state.

[0021] Furthermore, the cumulative Joule integral value is calculated as follows:

[0022]

[0023] Where i FU is the current flowing through the fuse, I e is the rated current value of the fuse, (I 2 t) (j) is the accumulated joule integral value.

[0024] Furthermore, the effectiveness of the tuning results is verified through the RLC loop experimental platform.

[0025] And, a ship DC switchboard fuse setting system taking into account arc breaking, comprising:

[0026] Parameter construction module: used to describe the fuse breaking and arcing process based on the Cassie arc model, establish the model parameter variation law by fitting test data through genetic algorithm, and construct the relationship between the impedance of the RLC series test circuit and the arc time constant and arc voltage constant of the Cassie arc model through BP neural network;

[0027] Dynamic mapping module: Calculates the test loop impedance parameters that can be equivalent to the system short-circuit fault current waveform based on the equivalent short-circuit impedance of the system fault branch, the ratio of the test loop current peak to the short-circuit current peak, and maps the system short-circuit characteristics to the RLC test loop;

[0028] Setting execution module: It is used to iteratively select the fuses starting from the smallest branch group and then expanding to all branches in the system, with the constraints that the rated current of the fuse is not less than the product of the safety margin factor and the maximum continuous operating current of the branch, and the total joule integral value of the non-fault branch does not exceed 50% of its pre-arcing joule integral value. It adopts the minimum pre-arcing joule integral value priority strategy.

[0029] And, an electronic device includes a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor implements the steps of the above method when executing the program.

[0030] A non-transitory computer-readable storage medium stores a computer program, which implements the steps of the method described above when executed by a processor.

[0031] Compared with the prior art, the present invention and its preferred embodiments have at least the following beneficial effects:

[0032] Significantly improve protection reliability: Through the genetic algorithm, the arcing model parameters are adaptively fitted, breaking through the limitations of traditional fixed parameters or empirical formulas, accurately quantifying the arcing characteristics of the fuse, avoiding the risk of false operation of non-fault branches due to model distortion, and solving the problem of selective protection failure from the root cause.

[0033] Achieve dynamic matching of system-level characteristics: An innovative system-test loop parameter mapping mechanism is proposed to dynamically adjust model parameters based on the short-circuit current peak ratio, so that the arcing model can adapt to the actual operating conditions of the ship's DC system in real time, overcoming the defect that the static equivalent model cannot respond to multi-branch coupling characteristics.

[0034] Taking into account both rapid protection and selectivity: The iterative selection is driven by the minimum pre-arc Joule integral value priority strategy. Under the premise of meeting the strict Joule integral constraints of the non-fault branch (≤50% of the pre-arc value), the fastest-acting fuse model is given priority, achieving millisecond-level fault rapid clearance and zero false operation in non-fault areas.

[0035] Ensure efficient convergence of the tuning process: Based on the iterative process of gradually expanding the minimum branch group, it avoids global traversal calculation redundancy. Combined with the state switching logic of the piecewise equivalent model, it greatly improves the tuning efficiency of complex systems. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] The present invention is further described in detail below with reference to the accompanying drawings and specific embodiments:

[0037] Figure 1 This is an overall schematic diagram of a DC IPS DC distribution board fuse setting method according to an embodiment of the present invention.

[0038] Figure 2 Schematic diagram of the entire process of DC IPS short-circuit fault protection according to an embodiment of the present invention, wherein (a) is a typical structure of the DC IPS for electric boats according to an embodiment of the present invention and a schematic diagram of its short-circuit fault; (b) is a schematic diagram of the fuse breaking process according to an embodiment of the present invention.

[0039] Figure 3 Schematic diagram of the equivalent model of the fuse in the pre-arcing stage under a DC IPS short-circuit fault according to an embodiment of the present invention.

[0040] Figure 4 Schematic diagram of the equivalent model of fuse segments according to an embodiment of the present invention.

[0041] Figure 5 This is a flow chart of branch fuse setting according to an embodiment of the present invention.

[0042] Figure 6 This is a flow chart of busbar fuse setting according to an embodiment of the present invention. DETAILED DESCRIPTION

[0043] In order to make the features and advantages of the present invention more clearly understood, the following embodiments are given for detailed description:

[0044] It should be noted that the following detailed descriptions are exemplary and are intended to provide further explanation of the present application. Unless otherwise specified, all technical and scientific terms used in this specification have the same meanings as those commonly understood by those skilled in the art to which this application belongs.

[0045] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present application. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, they indicate the presence of features, steps, operations, devices, components and / or combinations thereof.

[0046] To enhance the selectivity and speed of DC IPS short-circuit fault protection, this embodiment proposes a DC IPS short-circuit fault protection selectivity analysis and setting method that takes fuse arcing into account. Based on experimental results, the impact of the fuse arcing process on DC IPS short-circuit fault protection is clarified. A fuse arcing model, DC IPS parameters, and fuse arcing model parameters are established to form a comprehensive model of the DC IPS short-circuit fault protection process. A DC IPS fuse setting scheme is proposed, and the effectiveness of the selected fuse signal is verified through experiments.

[0047] In view of the influence of fuse breaking characteristics on the rapidity and selectivity of short-circuit fault protection of ship DC integrated power system, this embodiment proposes a DC IPS short-circuit fault protection modeling and setting method considering fuse arcing, such as Figure 1 As shown in the figure. First, the arcing process of the fuse is described based on the Cassie model. Combined with the test data, the variation pattern of the model parameters is determined by genetic algorithm and described by BP neural network. Then, the short-circuit characteristics of the DC IPS are mapped to the fuse test circuit, and a full-process model of the DC IPS short-circuit fault protection is constructed to adapt to different fuse selections. Then, based on the constraints established by the China Classification Society standards, a DC IPS fuse setting method is proposed with the goal of achieving rapidity and selectivity of the DC IPS short-circuit fault protection. The fuse setting result can take into account both rapidity and selectivity of the short-circuit fault protection.

[0048] The following is the specific content of this embodiment:

[0049] 1 DC IPS short-circuit fault protection whole process modeling

[0050] 1.1 The entire protection process and the impact of fuse arcing

[0051] The typical system structure of DC IPS for offshore small pure electric ships is as follows: Figure 2 (a) shows the power side, which typically consists of a lithium battery pack, and the load side, which consists of a propulsion motor and daily loads. Energy is exchanged between the power and load sides via converters. Each converter is connected via a multi-section busbar. The converters and busbars form a DC distribution board. Fuses within the DC distribution board provide selective short-circuit protection for each branch and busbar segment.

[0052] When a short circuit occurs in the DC IPS distribution board, the converters of each branch discharge to the short circuit point through the busbar, for example Figure 2 (a) shows a short circuit fault at the output of the 1# DC / DC converter. The discharge current makes the fault branch current i SC The accumulated Joule heat of the fuse in this branch increases rapidly to the pre-arc Joule integral (I 2 t) pre-arcing The temperature of the fuse element increases sharply and melts after reaching the melting point. The arc begins to form in the gap between the breaking points of the fuse. This process is the pre-arc stage (e.g. Figure 2 (b)). The arc keeps the circuit connected, extending the protection time; after the arc is extinguished, the short-circuit current is blocked, the fault branch is removed, and the DC IPS short-circuit fault protection is completed. This process is the arcing stage (e.g. Figure 2 (b)), the Joule integral value after melting is the melting Joule integral (I 2 t) clearing During the arcing phase, the faulty branch remains in place, and the Joule integral values ​​of the fuses in both the faulty and non-faulty branches continue to increase, posing a risk of the non-faulty branch fuse blowing. Therefore, the DC IPS short-circuit protection setting should take the fuse arcing process into account. To ensure both rapid and selective DC IPS short-circuit protection, a full-process model of the DC IPS short-circuit protection is required, thereby developing a DC IPS short-circuit protection setting method that takes the fuse arcing process into account.

[0053] 1.2 Equivalent model of the forearc stage

[0054] When the DC IPS short-circuit impedance is small, the short-circuit current is mainly provided by the input or output capacitors of each branch converter. Figure 2 In the short-circuit fault (a), the output capacitors of the DC / DC converter, the input capacitors of the frequency converter and the inverter all discharge toward the short-circuit point, providing Joule heat that causes the fuse FU1 to melt. During the capacitor discharge process toward the short-circuit point, the DC IPS can be equivalent to Figure 3 The model shown. Each converter consists of a capacitor C j , capacitor series parasitic resistance R ESj Equivalent to an anti-parallel diode; the cable and busbar are connected by a resistor Rj and inductor L j Equivalent; the fuse is in the on state, equivalent to the resistance R FUj ; j is a positive integer, indicating the fuse number.

[0055] The equivalent resistance of the fuse is:

[0056] (1)

[0057] Where, I e is the rated current of the fuse, P e is the rated power loss.

[0058] In the pre-arcing stage, since the current flowing through the fuse rises very quickly and the fuse protection time is very short, the increase in the fuse on-resistance caused by the temperature rise of the fuse element can be ignored. Assuming R FUj At the same time, assuming that the heat dissipation power of the fuse remains at the rated value, the accumulated joule integral value of the fuse is:

[0059] (2)

[0060] Where i FU is the current flowing through the fuse, I e is the rated current value of the fuse. 2 t) (j) Greater than its own arc front joule integral value (I 2 t) (j)pre-arcing When the fuse enters the arcing stage.

[0061] 1.3 Equivalent model of arcing stage

[0062] During the breaking process, the fuse can be represented by a macroscopic arc mathematical model. Commonly used arc macroscopic mathematical models include Mayr, Cassie, and Ayrton. Among them, the Cassie arc model is suitable for arcing processes under high currents and is suitable for simulating the arcing process of a fuse breaking short-circuit currents. The Cassie arc mathematical model is as follows:

[0063] (3)

[0064] Where U C is the arc voltage constant, τ is the arc time constant, and g is the arc conductivity. The initial value of g is g (0) Much larger than 1 / R e , we can make g (0) is 10 8 R e .U C and τ should be able to be adjusted independently according to changes in fuse specifications and breaking conditions.

[0065] The test was conducted using an RLC series circuit. Combined with the fuse current obtained from the test, a genetic algorithm was used to optimize the equivalent model parameters of the fuse breaking process, with the goal of minimizing the standard deviation between the test current waveform and the equivalent model current waveform.

[0066] According to experimental results, τ can be approximated as a constant a; U C It is linearly related to the loop resistance, that is:

[0067] (4)

[0068] Where R test is the resistive component of the test circuit; A1, A2 and B are coefficients. Fuses of different specifications need to be fitted according to the test data.

[0069] 1.4 Method for determining fuse model parameters under DC IPS short circuit

[0070] Based on the above analysis, we establish Figure 4 The equivalent model of the fuse segment shown in the figure. According to the current Joule integral value of the fuse I 2 t and the arc front joule integral (I 2 t) Pre-arcing The fuse switches between the open and closed states according to the size relationship of the fuse.

[0071] Resistance R in the on state FUj Determined by formula (1). The parameters of the Cassie model in the disconnected state are determined by formula (4). In formula (4), the resistance R in the RLC series test circuit is test Determined by DC IPS parameters. The following is to determine R test principle.

[0072] The impedance of each branch of DC IPS is:

[0073] (5)

[0074] Let the fault branch be k, and the DC IPS has n branches in total. Then, according to the Thevenin equivalent principle, the equivalent short-circuit impedance of the DC IPS fault branch can be obtained as:

[0075] (6)

[0076] based on Figure 3 The model obtains the short-circuit current i of the DC IPS fault branch SC Waveform. Extract the current change Δi in a very short time Δt after the short circuit fault occurs SC , according to the busbar rated voltage U bus , the inductance of the RLC series test circuit of the fuse arcing characteristic is estimated to be:

[0077] (7)

[0078] Take the inductance L of each branch of DC IPS under short circuit fault k The mean value of is the inductance of the RLC series test circuit of the final fuse arcing characteristic, which is:

[0079] (8)

[0080] Assume that the capacitance of the RLC series test circuit is C test , then according to formula (6), the loop impedance deviation can be obtained as:

[0081] (9)

[0082] Calculate ΔZ according to the inverse Laplace transform formula test The time domain expression of the impulse function is taken as the resistance value R of the RLC series test circuit. test .

[0083] The first peak value of the loop current is obtained by the RLC series loop simulation model, which is recorded as I p . Based on Figure 3 The model obtains the peak value of the short-circuit current of the DC IPS fault branch as I p(SC) , then according to I p(SC) with I p Ratio magnification R test and L test , the resistive component of the final RLC series test circuit is:

[0084] (10)

[0085] R test(new) Substituting into formula (4), the model parameters of the fuse arcing process can be obtained, which can then be used in the DC IPS short-circuit fault protection setting process.

[0086] 2 DC IPS fuse setting method

[0087] Short-circuit fault protection for DC IPS (Direct Current Integral Switchgear) distribution boards requires both selectivity and speed. Since current marine fuses are passive protection components, fuse selection directly determines the effectiveness of DC IPS short-circuit fault protection, necessitating an optimal setting method.

[0088] 2.1 Constraints and objectives for fuse setting

[0089] The China Classification Society's "Guidelines for Inspection of Shipboard DC Integrated Power Systems" specifies the operating characteristics of fuses in DC IPS (Direct Current Switchgear) panels. Constraints and objectives are established based on these regulations.

[0090] Constraint 1: Rated current constraint. The rated current of the fuse is I e Should be greater than the maximum normal continuous working current I of the branch S This provision can be expressed as:

[0091] (11)

[0092] Wherein, α is the amplification factor that takes into account the ambient temperature, heat dissipation conditions, and safety margin, and α can be between 1 and 2.34. In this embodiment, α is set to 1.5.

[0093] Constraint 2: Short-circuit fault protection result constraint. After a short circuit occurs, the fuse closest to the fault point operates, thereby disconnecting the faulty area of ​​the DC IPS. Fuses in non-faulty areas do not operate, ensuring normal operation of electrical equipment in non-faulty areas.

[0094] Constraint 3: Total Joule integral value constraint. During the period from the occurrence of the short-circuit fault to the removal of the fault, the total Joule integral value (I 2 t) (j)all Should be less than the inherent pre-arcing Joule integral value of the fuse (I 2 t) (j)pre-arcing Half of . This rule can be expressed as:

[0095] (12)

[0096] Objective: The fuse setting result can take into account both the selectivity and speed of short-circuit fault protection.

[0097] Taking into account the differences in the protection ranges of branch fuses and busbar fuses in a DC IPS system, the setting methods for branch fuses and busbar fuses are established below.

[0098] 2.2 Branch Fuse Setting Process

[0099] When a short circuit occurs in a DC IPS branch, only the fuse of that branch will operate, while the fuses of the other branches and busbar will remain on. Figure 5 The branch circuit fuse setting process shown is as follows.

[0100] Step ①: According to the rated current of each branch of the DC IPS DC distribution board and constraint condition 1, determine the candidate library of fuse models for each branch. The fuses in the library are selected according to the pre-arc Joule integral value (I 2 t) pre-arcingSort them from small to large and select them in sequence during the setting process, so that the fuse setting result can take into account the speed of short-circuit fault protection.

[0101] Step ②: Randomly select 2 branches as the branch group to be adjusted. Initially select the fuse of the branch group, that is, take the fuse from the fuse selection library (I 2 t) pre-arcing The smallest model; and determine the parameters of the fuse model according to the fuse data sheet, DC IPS parameters and the method in Section 1.4.

[0102] Step ③: Adjust the fuses of the selected branch group. Figure 3 and Figure 4 The DC IPS and fuse models are shown in the figure, and the DC IPS short-circuit protection whole process model is established. The short-circuit simulation is carried out on each branch in the branch group in turn to determine whether the fuses of each branch meet the constraints 2 and 3. If the fuse of a non-fault branch does not meet the constraints with the fuse of the fault branch, the fuse of the non-fault branch is updated to the fuse in the alternative library (I 2 t) pre-arcing The next smallest model is simulated again. If the fuse selections for all branches have traversed the entire candidate library but still do not meet the constraints, it is considered that no fuse selection is available and the fuse candidate library should be expanded.

[0103] Step ④: If a short circuit occurs in each branch in the branch group, and each fuse meets constraints 2 and 3, then select a branch to form a new branch group, and select the fuse of this branch as the backup fuse (I 2 t) pre-arcing The smallest model and return to step ③. When the branch group includes all DC IPS branches and the branch group fuse setting is completed, the DCIPS branch fuse setting is completed.

[0104] 2.3 Busbar fuse setting process

[0105] The busbar fuse carries the energy exchange between the left and starboard busbars in the DC IPS. Therefore, the rated current I S It should be the maximum current value flowing through the busbar under various working conditions of DC IPS. In addition, when a short circuit fault occurs on the port or starboard busbar, the busbar fuse is disconnected and the non-faulty busbar and its branches maintain normal operation. Based on this, the following is established: Figure 6 The tuning process is shown in detail as follows.

[0106] Step ①: According to constraint 1, determine the candidate model library of busbar fuse. By selecting feasible solutions to concentrate busbar fuses (I 2 t) pre-arcing The smallest set is the final selection, which can take into account the rapidity of short-circuit fault protection.

[0107] Step 2: Load the pre-selected branch fuse types, determine the fuse parameters, and establish a full-process model for DC IPS short-circuit protection. Traverse the models in the busbar fuse selection library and traverse the short-circuit fault points. Determine whether all busbar fuse types in the library, when combined with branch fuses, meet the DC IPS short-circuit protection constraints. If all models in the busbar fuse selection library do not meet the constraints, update the branch fuse type that has failed to meet the constraints the most times and re-adjust the branch fuse. If the branch fuse is successfully adjusted, repeat step 2; if not, it indicates that there are no available options for DC IPS and the fuse selection library should be expanded. If there are options in the busbar fuse selection library that meet the constraints, proceed to step 3.

[0108] Step ③: Comprehensively consider the busbar fuse selection results and select the busbar fuse (I 2 t) pre-arcing The smallest fuse solution set indicates that the DC IPS fuse selection result takes into account both the selectivity and fastness of short-circuit protection.

[0109] 3. Innovation

[0110] This embodiment addresses the requirements for selectivity and rapidity in short-circuit fault protection for the DC integrated power system of electric ships. A full-process model for short-circuit fault protection that takes fuse breaking characteristics into account is established, and a fuse setting method for DC distribution boards is proposed. The main innovations are as follows:

[0111] (1) A full-process model of short-circuit fault protection that takes into account the fuse breaking characteristics is proposed. The smaller the short-circuit impedance of the ship's DC IPS and the larger the short-circuit current, the greater the proportion of the Joule integral value of the fuse breaking arcing stage in the full-process short-circuit protection and the greater the impact on the coordination of short-circuit fault protection. Based on the DC IPS short-circuit equivalent model to describe the pre-arcing process of the fuse, and based on the Cassie model to describe the fuse breaking arcing process, a full-process model of DC IPS short-circuit fault protection is constructed by combining the two.

[0112] (2) A fuse arcing characteristic model and its application method in the DC IPS short-circuit characteristics are proposed. Based on the test results of the fuse in the RLC series test circuit, the arc time constant and arc voltage constant of the Cassie model of the fuse arcing process are obtained using a genetic algorithm. The relationship between the RLC series test circuit parameters, arc time constant and arc voltage constant is described by a BP neural network, forming a fuse arcing characteristic model. A mapping method of the DC IPS short-circuit characteristics in the fuse RLC series test circuit is proposed. Based on the DC IPS short-circuit characteristics, the RLC series test circuit parameters are estimated and the fuse arcing process is obtained, which can accurately describe the entire process of DC IPS short-circuit fault protection.

[0113] (3) A fuse setting method for shipboard DC distribution boards was proposed. Based on the equivalent model of the entire short-circuit protection process of the shipboard DC integrated power system, the rated current of the fuse is not less than the product of the safety margin factor and the maximum continuous operating current of the branch, and the total Joule integral value of the non-fault branch does not exceed 50% of its pre-arcing Joule integral value as constraints. A minimum pre-arcing Joule integral value priority strategy was adopted. The iterative selection started from the smallest branch group and expanded to the entire system branches. A fuse setting scheme was established, which made the DC IPS short-circuit fault protection scheme both selective and rapid.

[0114] It should be noted that, based on the same inventive concept, the present invention is applicable to the modeling and setting of short-circuit fault protection for shipboard DC distribution boards, taking into account the disconnection process of protective devices. These protective devices include fuses, circuit breakers, and contactors. This method describes the disconnection process of the protective devices using arc models such as Mayr and Cassie. By fitting the disconnection process and test circuit parameters using a BP neural network, a segmented model of the protective device and a full-process model of DC IPS short-circuit fault protection are established. The protective device model is then set based on the constraints of DC IPS short-circuit fault selective protection, ensuring that the DC IPS short-circuit fault protection scheme is both selective and rapid.

[0115] Based on the same inventive concept, the present invention also provides a computer device, which includes: one or more processors and a memory for storing one or more computer programs; the program includes program instructions, and the processor is used to execute the program instructions stored in the memory. The processor may be a central processing unit (CPU), or other general-purpose processors, digital signal processors (DSP), application-specific integrated circuits (ASIC), field-programmable gate arrays (FPGA) or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. It is the computing core and control core of the terminal, which is used to implement one or more instructions, specifically for loading and executing one or more instructions in a computer storage medium to implement the above method.

[0116] It should be further explained that, based on the same inventive concept, the present invention also provides a computer storage medium having a computer program stored thereon, which, when executed by a processor, performs the above-described method. The storage medium may be any combination of one or more computer-readable media. The computer-readable medium may be a computer-readable signal medium or a computer-readable storage medium. The computer-readable storage medium may be, for example, but not limited to, an electrical, magnetic, optical, infrared, or semiconductor system, apparatus, or device, or any combination thereof. More specific examples (a non-exhaustive list) of computer-readable storage media include: an electrical connection having one or more conductors, a portable computer disk, a hard disk, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM or flash memory), optical fiber, a portable compact disk read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination thereof. In the present invention, a computer-readable storage medium may be any tangible medium containing or storing a program that can be used by or in conjunction with an instruction execution system, apparatus, or device.

[0117] It should be noted that, unless otherwise defined, the technical or scientific terms used in the present invention should have the usual meanings understood by people with ordinary skills in the field to which the present invention belongs. The "first", "second" and similar words used in the present invention do not indicate any order, quantity or importance, but are only used to distinguish different components. "Include" or "comprise" and similar words mean that the elements or objects appearing before the word include the elements or objects listed after the word and their equivalents, without excluding other elements or objects. "Connect" or "connected" and similar words are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect. "Up", "down", "left", "right" and the like are only used to indicate relative positional relationships. When the absolute position of the object being described changes, the relative positional relationship may also change accordingly.

[0118] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any other manner. Any person skilled in the art may utilize the above-disclosed technical content to modify or modify the present invention into equivalent embodiments. However, any simple modifications, equivalent variations, and modifications to the above embodiments that do not depart from the technical content of the present invention and are based on the technical essence of the present invention remain within the scope of protection of the present invention.

[0119] The present invention is not limited to the above-mentioned optimal embodiment. Anyone can derive various other forms of a fuse setting method for a ship DC distribution board taking into account arc interruption based on the inspiration of the present invention. All equivalent changes and modifications made within the scope of application of the present invention should fall within the scope of the present invention.

Claims

1. A method for setting fuses on a DC switchboard of a ship taking into account arc breaking, characterized by: Establishment of a fuse breaking arcing model: The fuse breaking arcing process is described based on the Cassie arc model. The variation pattern of model parameters is established by fitting test data using a genetic algorithm. The relationship between the impedance of the RLC series test circuit and the arc time constant and arc voltage constant of the Cassie arc model is constructed using a BP neural network. Map the short-circuit characteristics of the ship's DC integrated power system to the test circuit: Calculate the test circuit impedance parameters that can be equivalent to the system short-circuit fault current waveform based on the equivalent short-circuit impedance of the system fault branch, the ratio of the test circuit current peak to the short-circuit current peak; Execute constraint-driven fuse setting: With the constraints that the fuse rated current is not less than the product of the safety margin factor and the branch maximum continuous operating current, and the total Joule integral value of the non-fault branch does not exceed 50% of its pre-arcing Joule integral value, adopt a minimum pre-arcing Joule integral value priority strategy, iteratively select fuses starting from the smallest branch group and expanding to all branches in the system; The method of establishing a model parameter variation law includes: precharging a fixed capacitor voltage in an RLC series test circuit, minimizing the standard deviation of a test current waveform and an output waveform of a Cassie model by a genetic algorithm, obtaining multiple sets of data sets of resistance values, arc time constants, and arc voltage constants of the RLC series test circuit, and obtaining a law between resistance value and arc time parameter, and between resistance value and arc voltage constant by a BP neural network; The iterative selection includes: Branch fuse selection: Sort the candidate model library in ascending order by pre-arcing Joule integral value, build the initial branch group starting with the model with the smallest pre-arcing Joule integral value, further determine whether the branch group meets the constraints, and update the fuse models of branches that do not meet the constraints until all branch fuse models meet the constraints; Main bus tie fuse selection: Collaborate with branch fuses to verify constraints. If no feasible solution exists, update the branch fuse model and reselect.

2. A method for setting fuses of a DC switchboard of a ship taking into account arc breaking according to claim 1, characterized in that: The calculation of the equivalent short-circuit impedance of the fault branch is achieved by using the Thevenin equivalent principle.

3. The method for setting fuses of a DC switchboard of a ship taking into account arc breaking according to claim 1, characterized in that: Calculating the test loop impedance parameters includes: calculating the inductance of the test loop based on the initial change rate of the short-circuit current of the ship's DC integrated power system branch; estimating the resistance value of the test loop based on the inductance of the test loop, the preset capacitance and the calculated equivalent short-circuit impedance of the fault branch, and then obtaining the test loop short-circuit current peak value; and then adjusting the test loop resistance value based on the deviation between the test loop short-circuit current peak value and the system branch short-circuit current peak value, the adjusted test loop resistance value = (test loop short-circuit current peak value / system short-circuit current peak value) × original test loop resistance value.

4. The method for setting fuses of a DC switchboard on a ship taking arc breaking into consideration according to claim 1, characterized in that: The fuse adopts a segmented equivalent model: The on-state equivalent resistance is determined by the ratio of the rated power loss to the square of the rated current; When the accumulated joule integral value of the fuse exceeds the pre-arcing joule integral value, it switches to the arcing state.

5. A method for setting fuses of a DC switchboard on a ship taking arc breaking into consideration according to claim 4, characterized in that: The cumulative Joule integral value calculation formula is: Where, i FU is the current flowing through the fuse, I e is the rated current value of the fuse, ( I 2 t ) (j) is the accumulated joule integral value.

6. A shipboard DC switchboard fuse setting system taking into account arc breaking, characterized in that: Used to implement the method according to any one of claims 1 to 5, comprising: Parameter construction module: used to describe the fuse breaking and arcing process based on the Cassie arc model, establish the model parameter variation law by fitting test data through genetic algorithm, and construct the relationship between the impedance of the RLC series test circuit and the arc time constant and arc voltage constant of the Cassie arc model through BP neural network; Dynamic mapping module: Calculates the test loop impedance parameters that can be equivalent to the system short-circuit fault current waveform based on the equivalent short-circuit impedance of the system fault branch, the ratio of the test loop current peak to the short-circuit current peak, and maps the system short-circuit characteristics to the RLC test loop; Setting execution module: It is used to iteratively select the fuses starting from the smallest branch group and then expanding to all branches in the system, with the constraints that the rated current of the fuse is not less than the product of the safety margin factor and the maximum continuous operating current of the branch, and the total joule integral value of the non-fault branch does not exceed 50% of its pre-arcing joule integral value. It adopts the minimum pre-arcing joule integral value priority strategy.

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