Short-circuit simulation and selective protection method for ship direct-current power system and storage medium

Abstract

The invention discloses a ship DC power system short circuit simulation and selective protection method and a storage medium. The method comprises the following steps: modeling a power battery energy storage device, a high-speed fuse and an inversion device; the ship direct-current power system is constructed through the modules obtained through modeling; performing short-circuit fault setting on the ship direct-current power system obtained through simulation; and determining a short-circuit selective protection method so as to carry out short-circuit selective protection on the ship direct-current power system with the short-circuit fault through the short-circuit selective protection method. According to the method, the defects of ship direct-current power system short-circuit modeling and corresponding selective protection method design in existing research can be overcome, so that the simulation accuracy of the ship direct-current power system is ensured, and effective action protection can be realized when the ship direct-current power system has a short-circuit fault.

Description

Technical Field

[0001] The present invention relates to the technical field of short - circuit protection for ship DC power systems, and particularly to a short - circuit simulation and selective protection method and storage medium for ship DC power systems. Background Art

[0002] As a core component of the ship power system, the ship power system undertakes the important tasks of generating, distributing, transmitting, and consuming electrical energy, and is a key infrastructure to ensure the safe and efficient operation of ships. The ship power system is a complex and precise system, mainly composed of four major parts: power supply devices, distribution devices, power grids, and loads. In some industries such as ships, medical institutions, data processing centers, etc., the requirements for stable power supply of the power system are very high. Once a power failure or power interruption occurs, it will cause major safety accidents, resulting in huge losses of human and financial resources, and endangering public safety. Therefore, ensuring the stable operation of the distribution system is crucial for the continuity of industrial production and the economic benefits of enterprises. Developing preventive strategies for potential risks to avoid equipment failure and power outage accidents is crucial for public safety and the economic benefits of enterprises.

[0003] There have been some domestic studies on short - circuit calculations for ship power systems. Although these related technologies have promoted the development of the ship power system protection field, they still do not meet the protection requirements for ship power systems. The existing problems are as follows: First, the above - mentioned methods mainly focus on the calculation method of short - circuit current, and rarely mention the corresponding selective protection scheme; second, there is insufficient research on short - circuit simulation of ship DC power systems, especially in the modeling of related circuits and components and short - circuit protection analysis. Summary of the Invention

[0004] The present invention aims to solve at least to some extent the technical problems in the related technologies. For this purpose, the first object of the present invention is to provide a short - circuit simulation and selective protection method for ship DC power systems to make up for the lack of short - circuit modeling and corresponding selective protection method design in existing research for ship DC power systems.

[0005] The second object of the present invention is to provide a computer - readable storage medium.

[0006] The third object of the present invention is to provide an electronic device.

[0007] To achieve the above objects, the present invention is realized through the following technical solutions:

[0008] A short - circuit simulation and selective protection method for ship DC power systems includes:

[0009] Modeling a power battery energy storage device, a fast fuse, and an inverter device;

[0010] Construct a ship DC power system by building each module obtained through modeling;

[0011] Set short - circuit faults for the ship DC power system obtained by simulation;

[0012] Determine the short - circuit selective protection method, so as to perform short - circuit selective protection on the ship DC power system with short - circuit faults through the short - circuit selective protection method.

[0013] Preferably, model the power battery energy storage device, including:

[0014] Determine the number of series - connected single - cell batteries and the open - circuit voltage of a single - cell battery, so as to determine the open - circuit voltage of the power battery pack;

[0015] Determine the ohmic resistance, polarization resistance, and polarization capacitance of a single - cell battery, so as to model the power battery energy storage device in combination with the open - circuit voltage of the power battery pack.

[0016] Preferably, model the fast fuse, including:

[0017] Connect a single - pole double - throw switch in series with the circuit branch. The circuit branch includes a normal - state branch of the fast fuse and a blown - state branch of the fast fuse; the blown - state branch of the fast fuse is composed of a wire in series with a fuse resistance, the fuse resistance is a variable resistance, and the normal - state branch of the fast fuse is composed of a wire in series with a fixed resistance.

[0018] Preferably, the fuse resistance function is obtained by fitting the fuse resistance curve tested through experiments. The steps for determining the fuse resistance function are as follows:

[0019] Connect the external equivalent circuit of the fast fuse in series with the fast fuse, simulate the short - circuit situation and record the change curve of the fuse resistance with the joule integral;

[0020] Select multiple coordinates in the obtained change curve, and use the polyfit function in Matlab to perform polynomial fitting on the fuse resistance curve;

[0021] Take the joule integral as the input and the fuse resistance value as the output, and implement the logic of the fuse resistance value changing with the joule integral through the S - function, so as to determine the fuse resistance function; among them, the fuse resistance function is used to simulate the resistance change of the fast fuse during the fusing process.

[0022] Preferably, the short - circuit fault setting method includes:

[0023] Set short - circuit fault points at the power supply output terminal, the bus output terminal, and the input terminals of each branch respectively;

[0024] Short-circuit the incoming line end and the outgoing line end of the short-circuit point through the Ideal Switch in Matlab / Simulink;

[0025] Control the turn-off of the Ideal Switch through the Step step signal.

[0026] Preferably, the short-circuit selective protection method includes the design of the positions of the support capacitors and fast fuses, and the protection action strategy of the fast fuses when a short circuit occurs.

[0027] Preferably, the design of the positions of the support capacitors and fast fuses includes:

[0028] Connect the first support capacitor in parallel with the busbar;

[0029] Connect the second support capacitor and the third support capacitor in parallel with the inverter device, and connect a diode in the forward direction at the input end of the second support capacitor and the third support capacitor, and connect a diode in the reverse direction at the output end;

[0030] Connect the first and second fast fuses in series at the power supply output end;

[0031] Connect the third and fourth fast fuses, and the fifth and sixth fast fuses in series at the input ends of each branch respectively.

[0032] Preferably, the protection action strategy of the fast fuses when a short circuit occurs includes:

[0033] When a short circuit occurs in the power supply, the first support capacitor discharges to provide a fusing current for the first and second fast fuses to ensure that the first and second fast fuses quickly fuse to cut off the power supply, and the second support capacitor and the third support capacitor ensure that the AC parts of each branch do not lose power immediately;

[0034] When a short circuit occurs in the busbar, the power supply provides a fusing current for the first and second fast fuses to ensure that the first and second fast fuses quickly fuse to cut off the power supply;

[0035] When a short circuit occurs in the propulsion branch of the ship's DC power system, the first support capacitor provides a fusing current for the fifth and sixth fast fuses to ensure that the fifth and sixth fast fuses quickly fuse to cut off the branch;

[0036] When a short circuit occurs in the daily use inverter branch of the ship's DC power system, the first support capacitor provides a fusing current for the third and fourth fast fuses to ensure that the third and fourth fast fuses quickly fuse to cut off the branch.

[0037] To achieve the above object, the second aspect of the present invention provides a computer-readable storage medium, on which a computer program is stored. When the computer program is executed by a processor, the above-mentioned short-circuit simulation and selective protection method for the ship's DC power system is realized.

[0038] To achieve the above object, a third aspect of the present invention provides an electronic device, including a memory, a processor, and a computer program stored on the memory and executable on the processor. When the processor executes the computer program, the short-circuit simulation and selective protection method for the ship DC power system described above is implemented.

[0039] The present invention has at least the following technical effects:

[0040] The present invention provides a simulation method for a ship DC power system based on Matlab / Simulink, which includes four parts: modeling of a power battery energy storage device, modeling of a fast fuse, modeling of an inverter device, and a short-circuit fault setting method. By simplifying the actual ship DC power system into the above modules for modeling, the effect of simply, quickly, and intuitively simulating the circuit conditions can be achieved. The present invention also provides a short-circuit selective protection method for a ship DC power system, which includes two parts: design of the position of a support capacitor and a fast fuse, and design of the protection action of the fast fuse when a short circuit occurs. The fast fuse and the support capacitor are respectively divided into two categories according to different functions, which can quickly cut off the faulty branch when a short-circuit fault occurs in the DC part and ensure the normal operation of other branches.

[0041] Additional aspects and advantages of the present invention will be given in part in the following description, become apparent in part from the following description, or be understood through the practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 It is a flowchart of the short-circuit simulation and selective protection method for the ship DC power system according to an embodiment of the present invention.

[0043] Figure 2 It is a system block diagram of the short-circuit simulation and selective protection method for the ship DC power system according to an embodiment of the present invention.

[0044] Figure 3 It is a schematic diagram of the modeling of the power battery energy storage device according to an embodiment of the present invention.

[0045] Figure 4 It is a schematic diagram of the modeling of the fast fuse according to an embodiment of the present invention.

[0046] Figure 5 It is a schematic diagram of the method for obtaining the variable resistance value function of the fast fuse according to an embodiment of the present invention.

[0047] Figure 6 It is a schematic diagram of the topological structure of the ship DC power system according to an embodiment of the present invention.

[0048] Figure 7This is the simulation circuit diagram of the ship DC power system according to the embodiment of the present invention. Detailed implementation manners

[0049] The following details this embodiment. The examples of the embodiment are shown in the accompanying drawings, where the same or similar reference numerals denote the same or similar elements or elements with the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to explain the present invention and should not be construed as a limitation to the present invention.

[0050] The following describes the ship DC power system short-circuit simulation and selective protection method and storage medium according to this embodiment with reference to the accompanying drawings.

[0051] Figure 1 This is the flowchart of the ship DC power system short-circuit simulation and selective protection method according to the embodiment of the present invention. As Figure 1 shown, the method includes:

[0052] Step S101: Model the power battery energy storage device, fast fuse, and inverter device.

[0053] Step S102: Construct a ship DC power system through the modules obtained by modeling.

[0054] Step S103: Set short-circuit faults for the ship DC power system obtained by simulation.

[0055] Step S104: Determine the short-circuit selective protection method so as to perform short-circuit selective protection on the ship DC power system with short-circuit faults through the short-circuit selective protection method.

[0056] Figure 2 This is the system block diagram of the ship DC power system short-circuit simulation and selective protection method according to the embodiment of the present invention. Specifically, as Figure 2 shown, the ship DC power system short-circuit simulation and selective protection method according to the embodiment of the present invention specifically includes a ship DC power system short-circuit simulation method and a ship DC power system short-circuit selective protection method.

[0057] The ship DC power system short-circuit simulation method includes: a power battery energy storage device modeling method, a fast fuse modeling method, an inverter device modeling method, and a short-circuit fault setting method.

[0058] Construct a ship DC power system simulation circuit model through the modeling method, and collect and record the circuit parameters under short-circuit faults by setting short-circuit faults.

[0059] The ship DC power system short-circuit selective protection method includes: the design of the position of the support capacitor and the fast fuse, and the design of the protection action strategy of the fast fuse when a short circuit occurs.

[0060] Quick fuses are set for the power supply module, bus bar, daily use inverter module, and propulsion module respectively. The short-circuit fault parameters are collected through the above simulations to complete the selection of quick fuses.

[0061] The position of the support capacitor is designed by dividing the protection purpose, and the specification of the support capacitor is determined in combination with the specification of the quick fuse.

[0062] The designed support capacitor and quick fuse are verified through the simulation system, and the effect is judged. Thus, the short-circuit selective protection of the ship DC power system with short-circuit faults can be realized.

[0063] Figure 3 It is a modeling schematic diagram of the power battery energy storage device according to the embodiment of the present invention.

[0064] As Figure 3 shown, the modeling of the power battery energy storage device is as follows:

[0065] The power battery energy storage device of the ship DC power system is composed of small single-cell battery cores, and the power and voltage outputs that meet the requirements are realized through series and parallel connections.

[0066] Furthermore, the overall modeling of the power battery pack can be represented by the Thevenin equivalent circuit model.

[0067] Determine the number N sb of the series-connected single-cell battery cores, and determine the open-circuit voltage U OCV of the single-cell battery core according to the OCV-SOC (open-circuit voltage at different states and battery levels) characteristic curve provided by the manufacturer.

[0068] Furthermore, according to the formula U OC = N sb × U OCV determine the open-circuit voltage of the power battery pack, that is, U OC .

[0069] Furthermore, based on the battery ohmic resistance R0, polarization resistance R s , polarization capacitance C s provided by the manufacturer, combined with the open-circuit voltage of the power battery pack, the modeling of the power battery energy storage device can be realized.

[0070] Figure 4 It is a modeling schematic diagram of the quick fuse according to the embodiment of the present invention. As Figure 4 shown, the modeling of the quick fuse is as follows:

[0071] The fast fuse modeling consists of two parallel circuit branches in the normal state and the blown state, and is connected in series with the circuit branches through a single-pole double-throw switch. The circuit branches include the fast fuse normal state branch and the fast fuse blown state branch; the fast fuse blown state branch is composed of a wire in series with a fuse resistance, and the fuse resistance is a variable resistance, and the fast fuse normal state branch is composed of a wire in series with a fixed resistance.

[0072] Further, when the ship DC power system is operating normally, the fast fuse is in the normal state, and the single-pole double-throw switch S1 is connected to the fast fuse normal state branch, that is, the branch where the fixed resistance R2 is located.

[0073] When the branch where the fast fuse is located is short-circuited, the single-pole double-throw switch S1 is connected to the fast fuse blown state branch, that is, the branch where the variable resistance R1 is located, and the fast fuse normal state branch is disconnected.

[0074] As Figure 5 shown, the fast fuse blown state branch is composed of a wire in series with a variable resistance, and the variable resistance value function, that is, the fuse resistance function, is obtained by fitting the fuse resistance curve obtained from experimental tests. The specific steps are as follows:

[0075] When experimentally testing the fuse resistance curve, the external equivalent circuit of the fast fuse is connected in series with the measured fast fuse, simulating the short-circuit situation and recording the change curve of the fuse resistance with the Joule integral I 2 t.

[0076] Take as many coordinates as possible on the obtained change curve, and use the polyfit (curve fitting function) function in Matlab (simulation software) to perform polynomial fitting on the fuse resistance curve.

[0077] Implement the logic of the fuse resistance changing with the Joule integral in the S function (system function), and use the Joule integral as the input and the resistance value as the output to obtain the fuse resistance function.

[0078] In this implementation, the fuse resistance function is used to simulate the resistance change of the fast fuse during the fusing process, that is, obtaining this function can simulate the resistance change of the fuse during the fusing process, thereby making the simulation closer to the actual situation.

[0079] Further, the inverter device is modeled as follows:

[0080] The internal of the inverter device is a three-phase bridge inverter circuit, which can be built by using the Universal Bridge module in Matlab / Simulink.

[0081] Further, the short-circuit fault setting method includes:

[0082] Set short - circuit fault points at the power output terminal, bus output terminal, and input terminals of each branch respectively.

[0083] Short - circuit the incoming - line end and outgoing - line end of the short - circuit point through the Ideal Switch in Matlab / Simulink.

[0084] Furthermore, control the turn - off of the Ideal Switch through the Step step signal.

[0085] Among them, the Ideal Switch is open when the circuit is working normally and closed when a short - circuit occurs.

[0086] It should be noted that the topology structure of the ship's DC power system constructed by each module obtained through modeling in this embodiment is as Figure 6 shown. The structures on both sides of the ship are the same. Taking the port side as an example:

[0087] As Figure 6 shown, the positions of the support capacitors and fast fuses are designed as follows:

[0088] This solution determines the installation positions of two types of support capacitors.

[0089] The first support capacitor C1 is connected in parallel with the busbar to provide current for the fast fuse to blow.

[0090] The second support capacitor C2 and the third support capacitor C3 are connected in parallel with the inverter device, and diodes are connected in the forward direction at the input ends of the second support capacitor C2 and the third support capacitor C3 and in the reverse direction at the output ends to ensure that the relevant AC electrical appliances at the output ends of each branch inverter device will not lose power instantaneously when the power supply is cut off due to a power - supply short - circuit.

[0091] This solution determines the installation positions of two types of fast fuses.

[0092] The first fast fuse Fu1 and the second fast fuse Fu2 are connected in series at the power output terminal to ensure that the power supply is cut off in time when a short - circuit occurs at the power - supply end.

[0093] The third fast fuse Fu3 and the fourth fast fuse Fu4, the fifth fast fuse Fu5 and the sixth fast fuse Fu6 are respectively connected in series at the input ends of each branch to ensure that the branch is cut off in time when a short - circuit fault occurs in the branch.

[0094] Figure 7 is the simulation circuit diagram of the ship's DC power system in the embodiment of the present invention, which corresponds to the Figure 6 topology structure. Figure 7 The part indicated by the red arrow in Figure 6 and 7 is the short - circuit fault point. As shown in

[0095] When the power supply has a short circuit at ①, the first support capacitor C1 discharges to provide fusing current for the first fast fuse Fu1 and the second fast fuse Fu2 to ensure their rapid fusing and cut off the power supply. The second support capacitor C2 and the third support capacitor C3 ensure that the AC parts of each branch do not lose power immediately.

[0096] When the busbar has a short circuit at ②, the power supply module provides fusing current for the first fast fuse Fu1 and the second fast fuse Fu2 to ensure their rapid fusing and cut off the power supply, and then further conduct on-site inspections.

[0097] When the propulsion branch has a short circuit at ③, the first support capacitor C1 provides fusing current for the fifth fast fuse Fu5 and the sixth fast fuse Fu6 to ensure their rapid fusing and cut off the branch.

[0098] When the daily use inverter branch has a short circuit at ④, the first support capacitor C1 provides fusing current for the third fast fuse Fu3 and the fourth fast fuse Fu4 to ensure their rapid fusing and cut off the branch.

[0099] In summary, the present invention provides a simulation method for a ship DC power system based on Matlab / Simulink, which includes four parts: modeling of a power battery energy storage device, modeling of fast fuses, modeling of an inverter device, and a short-circuit fault setting method. By simplifying the actual ship DC power system into the above modules for modeling, the effect of simple, fast, and intuitive simulation of the circuit conditions can be achieved. The present invention also provides a short-circuit selective protection method for a ship DC power system, which includes two parts: the design of the position of the support capacitor and the fast fuse, and the design of the protection action of the fast fuse when a short circuit occurs. The fast fuses and the support capacitors are each divided into two categories according to different functions, which can quickly cut off the faulty branch when a short-circuit fault occurs in the DC part and ensure the normal operation of other branches.

[0100] Furthermore, the present invention also provides a computer-readable storage medium, on which a computer program is stored. When the computer program is executed by a processor, the above-mentioned short-circuit simulation and selective protection method for a ship DC power system is realized.

[0101] Furthermore, the present invention also provides an electronic device, which includes a memory, a processor, and a computer program stored on the memory and executable on the processor. When the processor executes the computer program, the above-mentioned short-circuit simulation and selective protection method for a ship DC power system is realized.

[0102] It should be noted that in this document, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "comprising", "including" or any other variant thereof are intended to cover non-exclusive inclusion, such that a process, method, article or device comprising a series of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article or device. Without further limitation, an element defined by the statement "comprising an..." does not exclude the presence of additional identical elements in the process, method, article or device comprising the element.

[0103] Although the content of the present invention has been described in detail through the above preferred embodiments, it should be recognized that the above description should not be considered as a limitation of the present invention. After those skilled in the art have read the above content, various modifications and alternatives to the present invention will be obvious. Therefore, the protection scope of the present invention should be defined by the appended claims.

Claims

1. A short-circuit simulation and selective protection method for a ship DC power system, characterized in that, Including: Modeling the power battery energy storage device, fast fuse, and inverter device; Constructing a ship DC power system from the modules obtained through modeling; Setting short - circuit faults for the simulated ship DC power system; Determining a short - circuit selective protection method to perform short - circuit selective protection on the ship DC power system with a short - circuit fault through the short - circuit selective protection method.

2. The short-circuit simulation and selective protection method for a ship DC power system according to claim 1, characterized in that, Modeling the power battery energy storage device, including: Determining the number of series - connected single - cell batteries and the open - circuit voltage of a single - cell battery to determine the open - circuit voltage of the power battery pack; Determining the ohmic resistance, polarization resistance, and polarization capacitance of a single - cell battery to model the power battery energy storage device in combination with the open - circuit voltage of the power battery pack.

3. The short-circuit simulation and selective protection method for a ship DC power system according to claim 1, characterized in that Modeling the fast fuse, including: Connecting a single - pole double - throw switch in series with a circuit branch, where the circuit branch includes a normal - state branch of the fast fuse and a blown - state branch of the fast fuse; the blown - state branch of the fast fuse is composed of a wire in series with a fuse resistance, the fuse resistance is a variable resistance, and the normal - state branch of the fast fuse is composed of a wire in series with a fixed resistance.

4. The short-circuit simulation and selective protection method for a ship DC power system according to claim 3, characterized in that The fuse resistance function is fitted from the fuse resistance curve obtained through experimental testing. The steps for determining the fuse resistance function are as follows: Connecting the external equivalent circuit of the fast fuse in series with the fast fuse, simulating a short - circuit situation and recording the change curve of the fuse resistance with the joule integral; Selecting multiple coordinates in the obtained change curve and using the polyfit function in Matlab to perform polynomial fitting on the fuse resistance curve; Taking the joule integral as the input and the fuse resistance value as the output, implementing the logic of the fuse resistance value changing with the joule integral through an S - function to determine the fuse resistance function; among them, the fuse resistance function is used to simulate the resistance change of the fast fuse during the fusing process.

5. The short-circuit simulation and selective protection method for a ship DC power system according to claim 1, characterized in that The short - circuit fault setting method includes: Setting short - circuit fault points at the power supply output terminal, bus output terminal, and input terminals of each branch respectively; Short - circuiting the incoming - line end and the outgoing - line end of the short - circuit point through the Ideal Switch in Matlab / Simulink; Controlling the turn - off of the Ideal Switch through a Step step signal.

6. The short-circuit simulation and selective protection method for the ship DC power system according to claim 1, characterized in that The short - circuit selective protection method includes the design of the support capacitor and the position of the fast fuse, and the protection action strategy of the fast fuse when a short - circuit occurs.

7. The short-circuit simulation and selective protection method for a ship DC power system according to claim 6, characterized in that, The design of the support capacitor and the position of the fast fuse includes: Connecting the first support capacitor in parallel with the busbar; Connecting the second support capacitor and the third support capacitor in parallel with the inverter device, and connecting a diode in the forward direction at the input terminal and a diode in the reverse direction at the output terminal of the second support capacitor and the third support capacitor; Connecting the first and second fast fuses in series at the power supply output terminal; Connecting the third and fourth fast fuses, and the fifth and sixth fast fuses in series at the input terminals of each branch respectively.

8. The short-circuit simulation and selective protection method for a ship DC power system according to claim 7, characterized in that, The protection action strategy of the fast fuse when a short - circuit occurs includes: When a short - circuit occurs at the power supply, the first support capacitor discharges to provide a fusing current for the first and second fast fuses to ensure that the first and second fast fuses quickly fuse to cut off the power supply, and the second support capacitor and the third support capacitor ensure that the AC part of each branch does not immediately lose power; When a short circuit occurs in the busbar, the power supply provides fusing current for the first and second fast fuses to ensure that the first and second fast fuses quickly fuse to cut off the power supply; When a short circuit occurs in the propulsion branch of the ship DC power system, the first support capacitor provides fusing current for the fifth and sixth fast fuses to ensure that the fifth and sixth fast fuses quickly fuse to cut off the branch; When a short circuit occurs in the daily use inverter branch of the ship DC power system, the first support capacitor provides fusing current for the third and fourth fast fuses to ensure that the third and fourth fast fuses quickly fuse to cut off the branch.

9. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by a processor, it implements the ship DC power system short circuit simulation and selective protection method according to any one of claims 1-8.

10. An electronic device, comprising a memory, a processor, and a computer program stored on the memory and executable on the processor, characterized in that, When the processor executes the computer program, it implements the ship DC power system short circuit simulation and selective protection method according to any one of claims 1-8.

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