Ship direct current distribution board fuse setting method considering on-off arcing

Abstract

The invention provides a ship direct current distribution board fuse setting method considering on-off arcing. Establishing a fuse breaking arcing model: describing a fuse arcing process based on a Cassie arc model, fitting test data through a genetic algorithm to establish a model parameter change rule, and establishing a relationship between a test loop resistance value and an arc voltage constant and an arc time constant through a BP neural network; the method comprises the following steps: calculating equivalent short-circuit impedance of a fault branch, and calculating a test loop impedance parameter which can be equivalent to a system short-circuit fault current waveform according to a short-circuit current peak proportional relation of a system and a test loop; and executing constraint driving type fuse setting: taking the condition that the rated current of the fuse is not less than the product of a safety margin coefficient and the maximum continuous working current of the branch and the total Joule integral value of the non-fault branch does not exceed 50% of the pre-arc Joule integral value as constraint conditions, and adopting a minimum pre-arc Joule integral value priority strategy, iteratively selecting the model from the minimum-scale branch group and expanding to a whole-system branch.

Description

Technical Field

[0001] The invention belongs to the technical field of ship power system protection, and particularly relates to a method for setting a fuse of a ship DC distribution board considering the breaking arcing. Background Technique

[0002] With the promotion of "carbon neutrality" in the ship and ocean field, the shipboard DC integrated power systems (DC IPS) bring great potential and opportunities for the transformation and upgrading of green ships, but at the same time, it also faces many challenges. Among them, short-circuit fault protection is an important research topic. In a low-impedance DC IPS, once a short-circuit fault occurs, a high-magnitude short-circuit current will cause a huge impact on vulnerable power electronic devices such as IGBTs and diodes in the system. If the fault branch is not cut off in time, the ship will be in danger of power failure, out of control, fire, etc.

[0003] In DC IPS, fast fuses with rapid action are mostly used as fuses. When a short-circuit fault occurs in the system, the fuse cuts off the fault current and removes the fault branch by melting the fuse element inside. However, whether the fuses of non-fault branches are opened is closely related to the short-circuit location, the arcing process of the opening of the fuse of the fault branch, etc. Therefore, reasonably setting the fuses of each branch in DC IPS to quickly remove short-circuit faults while meeting the requirements of selective protection is the key to ensuring the safe operation of the ship.

[0004] At present, the setting of fuses in DC IPS mainly adopts schemes such as comparing the fusing moments of fuses in each branch and comparing the intersection points of the branch current waveforms and the time-current characteristic curves of fuses. The implementation of the above schemes depends on the current calculation throughout the short-circuit protection process of DC IPS. The short-circuit current calculation of DC IPS is based on the equivalent models of components such as fuses and cables. Among them, whether the fuse model can accurately represent the physical characteristics of the fuse directly affects the accuracy of the short-circuit current calculation of DC IPS. The literature "Calculation and Analysis of the Arc Characteristics of High-Voltage Current-Limiting Fuses Based on a Semi-Empirical Model" analyzed the mechanism of the arc-burning process of high-voltage current-limiting fuses and established a semi-empirical calculation model for the arc-burning process, but did not consider the parameter selection problem after the fuse specifications change. The literature "Modeling of fuses for melting time and fusing current analysis" constructed a fuse model that calculates the fuse melting time and short-circuit current according to the Joule integral value. The literature "Simulation Study of Fuses in Ship DC Distribution System Based on MAYR Arc Model" constructed a MAYR arc model fuse model in Simulink based on the principle of the MAYR arc model, but only modeled a single fuse. The literature "An improved Mayr-type arc model based on current-zero measurements" improved the power dissipation coefficient of the MAYR arc model and dynamically adjusted the model parameters according to the voltage or current during the arc-burning process, so as to simulate the arc-burning process of high-voltage circuit breakers. Combining the fuse opening characteristic model and the DC IPS model can determine whether the DC IPS protection scheme meets selectivity. The literature "Design and Verification of Selective Protection for DC Networked Electric Propulsion System" equivalent the fuse to a series circuit model of a variable resistor and an inductor, analyzed the Joule integral values of fuses in each branch under different short-circuit points of DC IPS, and analyzed the short-circuit protection coordination based on the pre-arcing Joule integral value of the fuse, but did not clarify how to select fuses. The literature "Calculation of Short-Circuit Current and Analysis of Selective Protection of Fuses in Ship DC Distribution System" established a short-circuit current calculation model for DC IPS, calculated the Joule integral value of the fuse during the short-circuit process, determined the fuse disconnection according to the fusing Joule integral value, and thus analyzed the selectivity of the short-circuit fault protection, but ignored the influence of the fuse arc-burning process on the short-circuit current.

[0005] In summary, the current fuse model has not been combined with the setting of DC IPS short-circuit protection. In addition, the existing fuse setting methods for DCIPS mainly focus on the coordination of the melting moments of the fuse melts in each branch, ignoring the increase in the Joule integral value of the non-faulty branch caused by the arcing of the fuse in the faulty branch. Referring to the "Inspection Guide for Ship DC Integrated Power System" issued by the China Classification Society, the DC IPS short-circuit fault protection has detailed regulations on the actions of faulty and non-faulty fuses, Joule integral values, etc., and there is an urgent need to further establish a selection scheme. Summary of the Invention

[0006] Aiming at the defects and deficiencies of the existing technology, the present invention provides a fuse setting method for ship DC switchboards considering opening arcing. Based on the Cassie arc model to describe the fuse arcing process, the variation law of model parameters is established by fitting experimental data through a genetic algorithm. Using a BP neural network, the relationship between the resistance value of the test circuit, the arc voltage constant, and the arc time constant is constructed for the first time; a system short-circuit process - test circuit mapping mechanism is proposed. Based on the equivalent short-circuit impedance of the faulty branch and the proportional relationship between the peak short-circuit current of the test circuit and the system, the impedance parameters of the test circuit that can equivalent the short-circuit fault current waveform of the system are calculated to match the actual short-circuit current characteristics; an innovative constraint-driven iterative selection strategy is proposed, with the safety margin of the rated current and the Joule integral value of the non-faulty branch not exceeding 50% of the pre-arcing value as constraints. Starting from the model with the minimum pre-arcing Joule integral value, it is gradually extended from the smallest branch group to the entire system to achieve the balance of selectivity and rapidity of short-circuit protection. Experimental verification: The protection time of the faulty branch after setting is as low as about 7 milliseconds, and the risk of misoperation of the non-faulty branch is significantly reduced.

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

[0008] A fuse setting method for ship DC switchboards considering opening arcing:

[0009] Establishment of the fuse opening arcing model: Based on the Cassie arc model to describe the fuse opening arcing process, the variation law of model parameters is established by fitting experimental data through a genetic algorithm, and 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 a BP neural network.

[0010] Mapping the short-circuit characteristics of the ship DC integrated power system to the test circuit: According to the equivalent short-circuit impedance of the system faulty branch and the proportional relationship between the peak current of the test circuit and the peak short-circuit current, the impedance parameters of the test circuit that can equivalent the short-circuit fault current waveform of the system are calculated;

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

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

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

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

[0015] Further, the iterative selection includes:

[0016] Branch fuse selection: Arrange the alternative model library in ascending order of the pre-arcing joule integral value, construct the initial branch group from the model with the smallest pre-arcing joule integral value, further judge whether the branch group meets the constraint conditions, and update the fuse models of the branches that do not meet the constraint conditions until all branch fuse models meet the constraint conditions;

[0017] Bus tie fuse selection: Collaborate with the branch fuses to verify the constraint conditions. If there is no feasible solution, update the branch fuse models and re-select.

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

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

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

[0021] Furthermore, the calculation formula for the cumulative Joule integral value is as follows:

[0022]

[0023] In the formula, i FU is the current flowing through the fuse, I e is the rated current value of the fuse, and (I 2 t) (j) is the cumulative Joule integral value.

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

[0025] And, a fuse setting system for a ship DC distribution board considering opening and arcing includes:

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

[0027] Dynamic mapping module: Calculate the impedance parameters of the experimental loop that can equivalent the short - circuit fault current waveform of the system according to the proportional relationship between the equivalent short - circuit impedance of the system fault branch, the peak current of the experimental loop and the peak short - circuit current, and map the system short - circuit characteristics to the RLC experimental loop;

[0028] Setting execution module: used to take the fuse rated current not less than the product of the safety margin coefficient and the maximum continuous working current of the branch, and the total Joule integral value of the non - fault branch not exceeding 50% of its pre - arcing Joule integral value as the constraint conditions, adopt the strategy of giving priority to the minimum pre - arcing Joule integral value, and start iterative selection from the smallest - scale branch group and expand to all system branches.

[0029] And, an electronic device includes a memory, a processor, and a computer program stored on the memory and executable on the processor. When the processor executes the program, the steps of the above - mentioned method are implemented.

[0030] [[ID=3s5]]A non - transitory computer - readable storage medium stores a computer program, and when the computer program is executed by a processor, the steps of the above - mentioned method are implemented.

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

[0032] Significantly improve the protection reliability: By adaptively fitting the arc ignition model parameters through genetic algorithms, break through the limitations of traditional fixed parameters or empirical formulas, accurately quantify the arc ignition characteristics of fuses, avoid the risk of misoperation of non-faulty branches caused by model distortion, and fundamentally solve the problem of selective protection failure.

[0033] Achieve dynamic matching of system-level characteristics: Innovatively propose a system-test loop parameter mapping mechanism, dynamically adjust the model parameters according to the peak short-circuit current ratio, enable the arc ignition model to adapt to the actual working conditions of the ship DC system in real time, and overcome the defect that the static equivalent model cannot respond to the multi-branch coupling characteristics.

[0034] Balance the rapidity and selectivity of protection: Drive iterative selection with the priority strategy of the minimum pre-arcing joule integral value. On the premise of meeting the strict constraints of the joule integral of non-faulty branches (≤50% of the pre-arcing value), preferentially select the fuse model with the fastest action to achieve fast fault removal in milliseconds and zero misoperation in non-faulty areas.

[0035] Ensure efficient convergence of the setting process: Based on the iterative process of gradually expanding the minimum branch group, avoid the redundancy of global traversal calculation, and cooperate with the state switching logic of the segmented equivalent model to greatly improve the setting efficiency of complex systems. Description of the Drawings

[0036] The present invention will be further described in detail below in conjunction with the drawings and specific embodiments:

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

[0038] Figure 2 It is a schematic diagram of the whole process of short-circuit fault protection in the DC IPS according to an embodiment of the present invention. Among them, (a) is a schematic diagram of the typical structure of the DC IPS of an electric ship and its short-circuit fault according to an embodiment of the present invention; (b) is a schematic diagram of the fuse breaking process according to an embodiment of the present invention.

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

[0040] Figure 4 It is a schematic diagram of the segmented equivalent model of the fuse according to an embodiment of the present invention.

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

[0042] Figure 6 It is a flow chart of setting the bus tie fuse according to an embodiment of the present invention. Specific Embodiments

[0043] To make the features and advantages of the present invention more obvious and understandable, specific embodiments are given below and described in detail as follows:

[0044] It should be noted that the following detailed description is exemplary and is intended to provide further explanation of the present application. Unless otherwise specified, all technical and scientific terms used in this specification have the same meaning as commonly understood by those of ordinary skill in the technical field to which the present 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 "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0046] Regarding the selectivity and rapidity of DC IPS short - circuit fault protection, this embodiment proposes a method for analyzing and setting the selectivity of DC IPS short - circuit fault protection considering the arc - burning of fuses. Based on the test results, the influence degree of the fuse arc - burning process on DC IPS short - circuit fault protection is clarified. A fuse arc - burning model, DC IPS parameters, and parameters of the fuse arc - burning model are established to form a full - process model of DC IPS short - circuit fault protection. A DC IPS fuse setting scheme is proposed, and the effectiveness of the selected fuse signal is verified through experiments.

[0047] Regarding the influence of fuse breaking characteristics on the rapidity and selectivity of short - circuit fault protection in ship DC integrated power systems, this embodiment proposes a method for modeling and setting DC IPS short - circuit fault protection considering fuse arc - burning, as Figure 1 shown. First, the arc - burning process of the fuse is described based on the Cassie model. Combining with test data, the genetic algorithm is used to determine the variation law of the model parameters, which is described by the BP neural network. Then, the short - circuit characteristics of DC IPS are mapped into the fuse test circuit, and a full - process model of DC IPS short - circuit fault protection suitable for different fuse selections is constructed. Then, according to the China Classification Society standards, constraint conditions are constructed. With the goal of realizing the rapidity and selectivity of DC IPS short - circuit fault protection, a method for setting DC IPS fuses is proposed, and the fuse setting results can balance the rapidity and selectivity of short - circuit fault protection.

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

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

[0050] 1.1 Influence of the full - protection process and fuse arc - burning

[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 the inductor L j are equivalent; the fuse is in the conducting state and is equivalent to a resistor R FUj ; j is a positive integer representing the fuse number.

[0055] The equivalent resistance of the fuse is:

[0056] (1)

[0057] where I e is the rated current of the fuse and P e is the rated power loss.

[0058] In the pre-arcing stage, since the current flowing through the fuse rises extremely fast and the protection outlet time of the fuse is extremely short, the increase in the conduction resistance of the fuse caused by the fuse temperature rise can be ignored. Assume that R FUj remains unchanged. At the same time, assume that the heat dissipation power of the fuse remains at the rated value. Then the cumulative joule integral value of the fuse is:

[0059] (2)

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

[0061] 1.3 Equivalent model in the arcing stage

[0062] During the opening process, the fuse can be equivalent to an arc macroscopic mathematical model. Common arc macroscopic mathematical models include Mayr, Cassie, and Ayrton, etc. Among them, the Cassie arc model is applicable to the arcing process under large currents and is suitable for simulating the arcing process of the 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 conductance. The initial value of g (0) is much greater than 1 / R e , and g (0) can be set to 10 8 R e . U C and τ should be able to be adjusted autonomously according to the specifications of the fuse and the changes in the opening conditions.

[0065] The test is carried out using an RLC series circuit. Combining the fuse current obtained from the test and using the genetic algorithm, with the goal of minimizing the standard deviation between the test current waveform and the equivalent model current waveform, the parameters of the equivalent model of the fuse breaking process are optimized.

[0066] According to the experimental results, τ can be approximated as a constant a; U C has a linear relationship with the loop resistance, that is:

[0067] (4)

[0068] In the formula, R test is the resistive component of the test loop; A1, A2, and B are coefficients, and different specifications of fuses 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, the Figure 4 shown sectional equivalent model of the fuse is established. According to the current joule integral value I 2 t of the fuse and the magnitude relationship with the pre-arcing joule integral (I 2 t) Pre-arcing , the fuse switches between the off and on states.

[0071] The resistance R FUj in the on state is determined by Equation (1). The parameters of the Cassie model in the off state are determined by Equation (4). In Equation (4), the resistance R test in the RLC series test loop is determined by the DC IPS parameters. The following is the principle for determining R test .

[0072] Denote the impedance of each branch of the DC IPS as:

[0073] (5)

[0074] Denote the fault branch as k, and the DC IPS has a total of n branches. 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 the Figure 3 model, the short-circuit current i SC waveform of the DC IPS fault branch is obtained. Extract the current change amount Δi SC in a very short time Δt after the short-circuit fault occurs. According to the rated voltage U bus of the busbar, the inductance of the RLC series test loop for estimating the fuse arcing characteristics is:

[0077] (7)

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

[0079] (8)

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

[0081] (9)

[0082] Find the time - domain expression of ΔZ according to the Laplace inverse transform formula, and take the coefficient of the impulse function as the resistance value R of the RLC series test circuit test . test .

[0083] Obtain the first peak value of the loop current through the RLC series loop simulation model, denoted as I p . Denote based on Figure 3 The peak value of the short - circuit current of the DC - IPS fault branch obtained by the model is I p(SC) , then according to I p(SC) and I p Scale up R test and L test by the ratio, the resistive component of the final RLC series test circuit can be obtained as:

[0084] (10)

[0085] Substitute R test(new) into Equation (4), then the model parameters of the fuse arcing process can be obtained, and further used for the DC - IPS short - circuit fault protection setting process

[0086] 2 DC - IPS Fuse Setting Method

[0087] The short - circuit fault protection of the DC - IPS DC distribution board needs to have both selectivity and rapidity. Since the current marine fuse is a passive protection component, the selection of the fuse directly determines the DC - IPS short - circuit fault protection effect, and an optimization setting method needs to be established

[0088] 2.1 Constraints and Objectives of Fuse Setting

[0089] The "Inspection Guide for Ship DC Integrated Power System" issued by the China Classification Society has made relevant regulations on the working characteristics of fuses in the DC IPS DC distribution board. Based on this regulation, constraint conditions and objectives are established.

[0090] Constraint condition 1: Rated current constraint. The rated current I of the fuse e should be greater than the maximum normal continuous working current I of the branch where it is located S . This regulation can be expressed as:

[0091] (11)

[0092] where α is an amplification factor considering ambient temperature, heat dissipation conditions and safety margin, and α can take values from 1 to 2.34. In this embodiment, α is set to 1.5.

[0093] Constraint condition 2: Short-circuit fault protection result constraint. After a short circuit occurs, the fuse closest to the fault point operates, and then the fault area of the DC IPS is cut off; the fuses in the non-fault area do not operate to ensure the normal operation of electrical equipment in the non-fault area.

[0094] Constraint condition 3: Total joule integral value constraint. During the period from the occurrence of a short-circuit fault to the removal of the fault, the total joule integral value (I 2 t) (j)all of each fuse in the non-fault area should be less than half of the inherent pre-arcing joule integral value (I 2 t) (j)pre-arcing of the fuse. This regulation can be expressed as:

[0095] (12)

[0096] Objective: The fuse setting result can balance the selectivity and rapidity of short-circuit fault protection.

[0097] Considering the differences in the protection scopes of branch fuses and bus-tie fuses in the DC IPS system, the setting methods for branch fuses and bus-tie fuses are established separately below.

[0098] 2.2 Branch fuse setting process

[0099] When a short-circuit fault occurs in a DC IPS branch, only the fuse of that branch operates, and the fuses of the remaining branches and busbars remain conducting. Based on this, the branch fuse setting process shown below is established, specifically as follows. Figure 5 as shown below.

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

[0101] Step ②: Randomly select 2 branches as the branch group to be set. Initially select the fuses for this branch group, that is, select the model with the smallest (I 2 t) pre-arcing in the fuse alternative library; and determine the parameters of the fuse model according to the fuse data manual, DC IPS parameters and the method in Section 1.4.

[0102] Step ③: Set the fuses for the selected branch group. Combine the Figure 3 and Figure 4 shown DC IPS and fuse model to establish a full-process model of DC IPS short-circuit protection. Conduct short-circuit simulations on each branch in the branch group in turn to determine whether the fuses between the branches in each branch group meet Constraint Conditions 2 and 3. If the fuse of a non-fault branch does not meet the constraint conditions with the fuse of the fault branch, update the fuse of this non-fault branch to the model with the second smallest (I 2 t) pre-arcing value in the alternative library and conduct simulation judgment again. If the fuse selection of all branches has traversed the entire alternative library but still does not meet the constraint conditions, it is considered that there is no available fuse selection, and the fuse alternative library should be expanded.

[0103] Step ④: If all fuses meet Constraint Conditions 2 and 3 when short-circuit faults occur in each branch in the branch group, add one more branch to form a new branch group, select the fuse for this branch as the model with the smallest (I 2 t) pre-arcing in the alternative library, and return to Step ③. When the branch group includes all DC IPS branches and the fuse setting of the branch group is completed, the fuse setting of the DCIPS branch ends.

[0104] 2.3 DC Link Fuse Setting Process

[0105] The DC link fuse bears the energy interaction between the left and right busbars in the DC IPS. Therefore, the rated current I S at the DC link should be the maximum current value flowing through the busbar under various operating conditions of the DC IPS. In addition, when a short-circuit fault occurs in the left or right busbar, the DC link fuse opens, and the non-fault busbar and its branches remain normal. Based on this, establish the setting process as shown in Figure 6 as follows.

[0106] Step ①: Determine the alternative model library of the DC link fuse according to Constraint Condition 1. By selecting the set with the smallest (I 2 t) pre-arcing of the DC link fuse in the feasible solution set as the final selection, the rapidity of short-circuit fault protection can be taken into account.

[0107] Step ②: Load the initially selected branch fuse type, determine the fuse parameters, and establish a full-process model for the short-circuit protection of the DC IPS. Traverse the models in the backup library of the bus-tie fuse, and traverse the short-circuit fault points. Judge whether all the models of the bus-tie fuse in the library meet the DC IPS short-circuit protection constraint conditions after being matched with the branch fuse. If all the models in the bus-tie fuse selection library do not meet the constraint conditions, update the branch fuse type with the most times of non-compliance with the constraint conditions, and re-tune the branch fuse. If the branch fuse tuning is successful, repeat Step ②; if not, it indicates that there is no available selection for the DC IPS, and the fuse backup library should be expanded. If there is a selection in the bus-tie fuse selection library that meets the constraint conditions, proceed to Step ③.

[0108] Step ③: Based on the comprehensive bus-tie fuse selection results, select the bus-tie fuse (I 2 t) pre-arcing The smallest fuse solution set, indicating that the fuse selection result of this DC IPS takes into account both the selectivity and rapidity of short-circuit protection.

[0109] 3 Innovation

[0110] In this embodiment, aiming at the selectivity and rapidity requirements of the short-circuit fault protection of the DC integrated power system of electric ships, a full-process model of short-circuit fault protection considering the fuse breaking characteristics is established, and a fuse tuning method for the DC distribution board is proposed. The main innovations are as follows:

[0111] (1) A full-process model of short-circuit fault protection considering the fuse breaking characteristics is proposed. The smaller the short-circuit impedance of the ship's DC IPS, the larger the short-circuit current, and the greater the proportion of the Joule integral value in the fuse breaking and arcing stage in the whole process of 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, the pre-arcing process of the fuse is described, and based on the Cassie model, the fuse breaking and arcing process is described. By combining the two, a full-process model of the DC IPS short-circuit fault protection is constructed.

[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 by using the genetic algorithm. The relationship between the parameters of the RLC series test circuit, the arc time constant, and the 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 burning RLC series test circuit is proposed. Based on the DC IPS short-circuit characteristics, the parameters of the RLC series test circuit are estimated, and the fuse arcing process is obtained, so as to accurately describe the whole process of the DC IPS short-circuit fault protection.

[0113] (3) A method for setting the fuses of a ship's DC switchboard is proposed. Based on the equivalent model of the entire short-circuit protection process of a ship's DC integrated power system, with the constraint conditions that the rated current of the fuse is not less than the product of the safety margin coefficient and the maximum continuous working current of the branch, and the total Joule integral value of the non-faulty branches does not exceed 50% of its pre-arcing Joule integral value, a fuse setting scheme is established by adopting the strategy of giving priority to the minimum pre-arcing Joule integral value. Starting from the smallest-scale branch group, iterative selection is carried out and extended to all the branches of the system, so that the short-circuit fault protection scheme of the DC IPS takes into account both selectivity and rapidity.

[0114] It should be noted that, based on the same inventive concept, the present invention is applicable to the short-circuit fault protection modeling and setting of a ship's DC switchboard considering the opening process of the protection electrical appliances. The protection electrical appliances include fuses, circuit breakers, and contactors. This method can describe the opening process of the protection electrical appliances through arc models such as Mayr and Cassie, fit the parameters of the opening process and the test circuit through a BP neural network, establish a sectional model of the protection electrical appliances and a whole-process model of the short-circuit fault protection of the DC IPS, and set the type of the protection electrical appliances based on the constraint conditions of the selective protection of the short-circuit fault of the DC IPS, so that the short-circuit fault protection scheme of the DC IPS has both selectivity and rapidity.

[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 may also be other general-purpose processors, Digital Signal Processors (DSPs), Application Specific Integrated Circuits (ASICs), Field-Programmable Gate Arrays (FPGAs), 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, and is used to implement one or more instructions. Specifically, it is used to load and execute one or more instructions in the computer storage medium to implement the above method.

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

[0117] It should be noted that, unless otherwise defined, the technical terms or scientific terms used in the present invention should have the ordinary meaning understood by those with ordinary skills in the field to which the present invention belongs. The "first", "second", and similar terms used in the present invention do not denote any order, quantity, or importance, but are only used to distinguish different components. The terms such as "including" or "comprising" mean that the elements or objects appearing before this word cover the elements or objects listed after this word and their equivalents, without excluding other elements or objects. The terms such as "connected" or "coupled" are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect. The terms such as "up", "down", "left", "right", etc. are only used to represent relative positional relationships, and when the absolute position of the object being described changes, the relative positional relationship may also change accordingly.

[0118] As described above, these are only the preferred embodiments of the present invention, and the present invention is not limited to other forms. Any person skilled in the relevant art may use the disclosed technical content to make changes or modifications into equivalent embodiments with equivalent changes. However, any simple modifications, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present invention without departing from the technical solution content of the present invention still fall within the protection scope of the technical solution of the present invention.

[0119] The present invention is not limited to the above-mentioned optimal implementation manners. Anyone can derive various other forms of a method for setting a fuse of a ship DC switchboard considering the opening and arcing under the inspiration of the present invention. All equal changes and modifications made according to the scope of the application of the present invention shall fall within the scope covered by the present invention.

Claims

1. A method for setting the fuses of a ship's DC switchboard considering the arc interruption during opening, characterized in that: Establishment of the fuse opening arc model: Based on the Cassie arc model to describe the fuse opening arc process, the variation law of the model parameters is established by fitting the test data through the genetic algorithm, and 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 the BP neural network; Mapping the short-circuit characteristics of the ship's DC integrated power system to the test circuit: According to the equivalent short-circuit impedance of the system fault branch and the proportional relationship between the peak current of the test circuit and the peak short-circuit current, calculate the impedance parameters of the test circuit that can equivalent the short-circuit fault current waveform of the system; Execute constraint-driven fuse setting: Taking the rated current of the fuse not less than the product of the safety margin coefficient and the maximum continuous working current of the branch, and the total Joule integral value of the non-fault branch not exceeding 50% of its pre-arcing Joule integral value as the constraint conditions, adopting the strategy of giving priority to the minimum pre-arcing Joule integral value, start the iterative selection from the smallest-scale branch group and expand to all the branches of the system.

2. The method for setting the fuses of a ship's DC switchboard considering the arc interruption during opening according to claim 1, characterized in that: The establishment of the variation law of the model parameters includes: pre-charging a fixed capacitor voltage in the RLC series test circuit, minimizing the standard deviation between the test current waveform and the output waveform of the Cassie model through the genetic algorithm to obtain multiple sets of data of the resistance value, arc time constant and arc voltage constant of the RLC series test circuit, and obtaining the law between the resistance value and the arc time parameter, and the law between the resistance value and the arc voltage constant through the BP neural network.

3. The method for setting the fuses of a ship's DC switchboard considering the arc interruption during opening according to claim 1, characterized in that: Calculating the equivalent short-circuit impedance of the fault branch is realized by using the Thevenin equivalent principle.

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

5. The method for setting the fuses of a ship's DC switchboard considering the arc interruption during opening according to claim 1, characterized in that: The iterative selection includes: Selection of branch fuses: Arrange the alternative model library in ascending order of the pre-arcing Joule integral value, start constructing the initial branch group from the model with the smallest pre-arcing Joule integral value, further judge whether the branch group meets the constraint conditions, and update the fuse models of the branches that do not meet the constraint conditions until the fuse models of all branches meet the constraint conditions; Selection of bus-tie fuse: Coordinate with branch fuses to verify the constraint conditions. If there is no feasible solution, update the branch fuse model and re-select.

6. A method for setting the fuse of a ship DC distribution board considering opening and arcing, 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 cumulative joule integral value of the fuse exceeds the pre-arcing joule integral value, it switches to the arcing state.

7. A method for setting the fuse of a ship DC distribution board considering opening and arcing, according to claim 6, characterized in that: The calculation formula of the cumulative joule integral value is: Wherein, 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 cumulative joule integral value.

8. A fuse setting system for a ship DC switchboard considering the breaking arcing, characterized in that, Including: Parameter construction module: Used to describe the fuse opening and arcing process based on the Cassie arc model, establish the variation law of model parameters by fitting experimental data through the genetic algorithm, and construct the relationship between the impedance of the RLC series experimental circuit and the arc time constant and arc voltage constant of the Cassie arc model through the BP neural network; Dynamic mapping module: Calculate the impedance parameters of the experimental circuit that can equivalent the short-circuit fault current waveform of the system according to the ratio relationship between the equivalent short-circuit impedance of the system fault branch, the peak current of the experimental circuit and the peak short-circuit current, and map the system short-circuit characteristics to the RLC experimental circuit; Setting execution module: Used to take the rated current of the fuse not less than the product of the safety margin coefficient and the maximum continuous working current of the branch, and the total joule integral value of the non-fault branch not exceeding 50% of its pre-arcing joule integral value as the constraint conditions, adopt the strategy of giving priority to the minimum pre-arcing joule integral value, and start iterative selection from the smallest scale branch group and expand to all system branches.

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