Intensive bus duct phase sequence optimization arrangement calculation method

Abstract

The invention discloses an intensive bus duct phase sequence optimization arrangement calculation method, which comprises the following steps of: firstly, determining a bus duct model and all phase sequence arrangement modes thereof, and establishing a bus duct geometric model by utilizing modeling software; secondly, importing the model into electromagnetic transient simulation software, establishing a three-dimensional electromagnetic model of the intensive bus duct in modes of excitation application, grid division and the like, and solving and extracting the electrodynamic force of each phase line; a phase sequence arrangement sequence is given according to the size sequence of the electrodynamic force, a curve that the electrodynamic force changes along with the phase sequence is drawn, and a change trend is obtained by fitting an equation; and finally, giving out bus duct phase sequence arrangement suggestions according to a calculation result in combination with engineering practice. According to the method, the characteristics of flexible simulation setting, low cost and high working efficiency are fully utilized, the electrodynamic force values of the bus duct in different phase sequence arrangement modes can be accurately obtained, the optimal phase sequence arrangement mode of the bus duct is provided, and data and method support is provided for theoretical research, design, construction and operation and maintenance of the intensive bus duct.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of bus duct design and operation, in particular to a dense bus duct phase sequence optimization arrangement calculation method. BACKGROUND

[0002] Bus ducts are widely used in low-voltage power transmission trunk line engineering projects, such as indoor substations, high-rise buildings, and factory buildings, due to their compact structure, small space occupation, convenient construction, and large load capacity. However, when the copper bus bars in the bus duct are connected to alternating current, an electric force is generated, which causes the entire bus duct to vibrate. In particular, when a three-phase short circuit occurs in the bus duct, the peak value of the short-circuit current can reach hundreds of kA, resulting in deformation of the copper bars, damage to the shell and support, and ultimately destruction of the entire bus duct, threatening the long-term safe operation of the power system. When the phase sequence arrangement changes, the magnetic field distribution around the three-phase copper bars of the bus duct will change, thereby affecting the short-circuit electric force they experience. Therefore, it is of great significance to calculate the electric force of each phase line under various phase sequence arrangement combinations of the bus duct and find the optimal phase sequence arrangement that minimizes the electric force.

[0003] Currently, research on electric force mainly focuses on cables, transmission lines, and transformers, while research on bus ducts mainly focuses on temperature distribution, eddy current analysis, and thermal expansion force. However, there is little systematic research on the magnetic field distribution and electric force variation characteristics of dense bus ducts under three-phase current excitation, and even less research on the impact of phase sequence arrangement on electric force. Therefore, establishing an electromagnetic finite element model of dense bus ducts to study the above-mentioned content provides a theoretical basis for the theoretical research, design, and construction of dense bus ducts.

[0004] To address the above problems, the present application establishes a dense bus duct phase sequence optimization arrangement calculation method to determine the electric force values of each phase line of the bus duct under different phase sequence arrangements and provide arrangement recommendations. SUMMARY

[0005] In view of the shortcomings of the prior art, the present application proposes a dense bus duct phase sequence optimization arrangement calculation method, which can solve the problems of difficult and inaccurate electric force calculation of dense bus ducts under different phase sequence arrangements, and provides an optimal phase sequence arrangement, providing data and method support for the theoretical research, design, construction, and operation and maintenance of dense bus ducts.

[0006] To solve the above technical problems, the technical solution provided by the present application is a dense bus duct phase sequence optimization arrangement calculation method, characterized in that the method comprises:

[0007] Step S101, determine the model of the bus duct and all its phase sequence arrangements, and establish a geometric model of the bus duct using modeling software;

[0008] Step S102, importing the model into the electromagnetic transient simulation software, establishing the dense bus duct three-dimensional electromagnetic model by applying excitation, meshing, etc., solving and extracting the electric force of each phase line;

[0009] Step S103, giving the phase sequence arrangement order according to the electric force size order, drawing the curve of the electric force changing with the phase sequence, and fitting the equation to obtain the change trend;

[0010] Step S104, comparing the electric force of the bus duct under different arrangement modes, and giving the phase sequence arrangement suggestion of the bus duct according to the finite element simulation results and engineering practice.

[0011] Further, the bus duct model and all phase sequence arrangement modes are determined in step S101, and a modeling software is used to establish the bus duct geometric model, which specifically includes:

[0012] Step S1011, determining the bus duct model;

[0013] Step S1012, if it is a three-phase four-wire system, the A, B, C three-phase N line needs to be arranged and combined to determine the phase sequence arrangement mode of the bus duct. The A, B, C three-phase and N line are all made of copper busbars of the same size wrapped with polyester film insulation. Arranging and combining ABCN can get 24 arrangement and combination modes. Considering that the bus duct arranged according to the ABCN arrangement mode is the bus duct arranged according to the NCBA arrangement mode, and the copper bars in the bus duct do not change in position, it is considered that the two arrangement modes are repeated, so arranging and combining ABCN can get 12 non-repeated arrangement and combination modes, which are NABC, ANBC, ABNC, ABCN, NACB, ANCB, ACNB, ACBN, NBAC, BNAC, BANC and BACN. If the bus duct model is a three-phase five-wire system, the A, B, C three-phase N, PE line needs to be arranged and combined to determine the phase sequence arrangement mode of the bus duct. Considering that the PE line needs to be grounded, the PE line arrangement position has 2, which are the first left and first right positions close to the shell. Adding the PE line to arrange in the 12 non-repeated arrangement and combination modes of the three-phase four-wire system, a total of 24 non-repeated arrangement and combination modes are obtained, which are NABCPE, ANBCPE, ABNCPE, ABCNPE, NACBPE, ANCBPE, ACNBPE, ACBNPE, NBACPE, BNACPE, BANCPE, BACNPE, PENABC, PEANBC, PEABNC, PEABCN, PENACB, PEANCB, PEACNB, PEACBN, PENBAC, PEBNAC, PEBANC and PEBACN;

[0014] Step S1013, the geometric model of the bus duct is established by the geometric module of the finite element software, and the bus duct models of all phase sequence arrangement modes of the type are obtained by mirror function, changing the current excitation application sequence and other operations.

[0015] Further, in step S102, the model is imported into the electromagnetic transient simulation software, and a dense bus duct three-dimensional electromagnetic model is established by applying excitation, mesh division and other methods, and each phase line electric force is solved and extracted, specifically including:

[0016] Step S1021, determine the electromagnetic transient simulation software, such as MAXWELL and similar computer-aided design software, select the transient analysis type, and establish the geometric model of the dense bus duct and the finite element model of the surrounding magnetic field distribution area according to the actual structure shape and size;

[0017] Step S1022, select the built-in copper material of the software as the copper conductor material of the bus duct; through the query of the material manual, add the polyester film insulation layer and the aluminum-magnesium alloy shell material of the bus duct, and determine the material parameters such as electrical conductivity and relative magnetic permeability;

[0018] Step S1023, according to the characteristics of the bus duct operation, determine the maximum value of the periodic component, the angular frequency and the initial phase angle of the three-phase current excitation, and apply the current excitation on the A, B and C three-phase copper conductors, and do not apply the current excitation on the N and PE lines;

[0019] Step S1024, the dense bus duct has a multi-layer structure, and the copper conductor is the key part of the magnetic field generation and force, so the copper conductor should be subjected to grid encryption processing; the larger the volume of the calculation domain, the more the magnetic field distribution around the bus duct conductor, and the more accurate the electric force calculation, so the appropriate grid should be used for the calculation domain to ensure the calculation speed and accuracy;

[0020] Step S1025, add the "force" parameter to the copper conductor of the bus duct for electric force calculation; set the calculation time length of the transient analysis, the calculation time of each step, calculate and export the electric force data.

[0021] Further, in step S103, the phase sequence arrangement order is given according to the size order of the electric force, the curve of the electric force changing with the phase sequence is drawn, and the change trend is obtained by fitting equation, specifically including:

[0022] Step S1031, number the phase sequence arrangement modes according to the order of the electric force from large to small;

[0023] Step S1032, let the above number be the independent variable X and the electric force value be the dependent variable Y, and use drawing software to draw the curve of the electric force changing with the phase sequence;

[0024] Step S1033, select the polynomial fitting method to obtain the fitting equation.

[0025] Further, the bus duct electric power under different arrangement modes is compared in step S104, and the bus duct phase sequence arrangement suggestion is given according to the finite element simulation result, specifically including:

[0026] Step S1041, comparing the maximum electric power of each phase line of the bus duct under different phase sequence arrangement modes;

[0027] Step S1042, selecting the arrangement mode with small difference in the maximum electric power, calculating the average electric power of each phase line and comparing;

[0028] Step S1043, selecting the phase sequence arrangement mode with relatively large maximum electric power of each phase line and small average electric power of each phase line as the optimal phase sequence arrangement combination of the bus duct.

[0029] The beneficial effects of the application are: 1. The characteristics of the finite element analysis method are fully utilized, the finite element model of the dense bus duct can be accurately and quickly established, and the electric power values of each phase line of the bus duct under different phase sequence arrangement modes can be accurately obtained; 2. The application overcomes the shortcomings of difficult calculation, large error by formula method, and complex entity experiment and high cost; 3. The application can find an optimal phase sequence arrangement mode, and provide data support for the theoretical research, design, construction and operation of the dense bus duct. BRIEF DESCRIPTION OF DRAWINGS

[0030] Figure 1 It is a flow chart of a dense bus duct phase sequence optimization arrangement calculation method;

[0031] Figure 2 It is a dense bus duct structure diagram;

[0032] Figure 3 It is a three-phase current excitation diagram;

[0033] Figure 4 It is a grid subdivision effect diagram;

[0034] Figure 5 It is a curve diagram of the electric power of the bus duct changing with the phase sequence;

[0035] Figure 6 It is a comparison diagram of the electric power of each phase of the bus duct under different phase sequence arrangement modes. DETAILED DESCRIPTION

[0036] The flow chart of the dense bus duct phase sequence optimization arrangement calculation method given by the application is shown in Figure 1 In order to make the purpose, technical scheme and advantages of the application more clear and obvious, the application will be further and specifically described in combination with the drawings and implementation examples. It should be understood that the specific implementation examples described herein are only used to explain the application, and are not used to limit the application.

[0037] An embodiment is listed below.

[0038] The application provides a dense bus duct phase sequence optimization arrangement calculation method, which takes 1600A three-phase five-wire system dense bus duct normal working condition as an example for calculation.

[0039] 1. Determine all phase sequence arrangement modes of the bus duct and establish a geometric model thereof

[0040] The dense bus duct is composed of three parts of copper busbar, polyester film insulation and aluminum-magnesium alloy shell, and a finite element geometric model is established according to the actual structure as shown in the drawing. Figure 2 The five copper busbars are N, A, B, C and PE from left to right.

[0041] The arrangement mode of the phase sequence of the bus duct is determined by arranging and combining the N and PE lines of the A, B and C three-phase lines, and the PE line needs to be grounded, so the PE line arrangement position is 2, which is the left and right positions close to the shell. The A, B and C three-phase lines and the N line are all made of copper busbars of the same size wrapped with polyester film insulation. Arranging and combining ABCN can obtain 24 arrangement and combination modes. Considering that the bus duct arranged according to the ABCN arrangement mode is the bus duct arranged according to the NCBA arrangement mode and the copper busbar position does not change, it is considered that the two arrangement modes are repeated, so arranging and combining ABCN can obtain 12 non-repeated arrangement and combination modes. Then, the PE line is arranged, and 24 non-repeated arrangement and combination modes are obtained, which are NABCPE, ANBCPE, ABNCPE, ABCNPE, NACBPE, ANCBPE, ACNBPE, ACBNPE, NBACPE, BNACPE, BANCPE, BACNPE, PENABC, PEANBC, PEABNC, PEABCN, PENACB, PEANCB, PEACNB, PEACBN, PENBAC, PEBNAC, PEBANC and PEBACN. Through the mirror image function and changing the current excitation application sequence, the bus duct models of the above 24 phase sequence arrangement modes are obtained.

[0042] 2. Establish a three-dimensional electromagnetic model of the dense bus duct

[0043] The finite element analysis method can flexibly set the current excitation, conductivity, relative permeability, various boundary conditions and the like, and can more comprehensively simulate the magnetic field distribution and electric force around the bus duct.

[0044] The material parameters of each part of the bus duct are shown in Table 1.

[0045] Table 1 Material parameters of each part of the bus duct

[0046] Material name Cross-sectional dimension / (mm*mm) Electrical conductivity (m / s) Relative magnetic permeability Copper busbar 125×6 58000000 0.999991 Polyester film insulation 133×35 0 1 Aluminum-magnesium alloy housing 180×185 27027027 1

[0047] Transient electromagnetic field calculations were performed to determine the electrodynamics of the busbar trunking, and its characteristics were analyzed. The computational domain was set to air, and the vector magnetic potential at the outer boundary of the domain was set to 0 Wb / m (first-type boundary condition). To ensure no current leakage, the end faces of the busbar trunking were aligned with the computational domain, and a 50Hz three-phase AC excitation was applied to the A, B, and C phase end faces of the busbar trunking. Figure 3 As shown. There is no current in the N-line and PE-line.

[0048] Mesh generation effect as follows Figure 4 As shown. In the finite element analysis calculation process, mesh generation is a crucial step in establishing the finite element model, and the mesh type directly affects the calculation accuracy and scale. Since the electrodynamic force experienced by the busbar during operation is generated by the alternating current flowing through the copper busbar, and the other layers of the busbar have a relatively small impact on the numerical results of the electrodynamic force, a denser mesh is used for the copper busbar, while a relatively sparse mesh is used for the computational domain to ensure calculation speed.

[0049] The solver calculation time is set to 40ms (two cycles) with a step size of 0.4ms. A "force" parameter is added to the copper conductors of the busbar trunking to calculate the electrodynamic force. When the phase sequence arrangement changes, the magnetic field distribution around the copper busbar trunking changes, thus affecting the electrodynamic force it experiences in the magnetic field. The electrodynamic force of each phase under each combination is calculated to find the optimal phase sequence arrangement that minimizes the electrodynamic force.

[0050] 3. Plot the curve of electrodynamic force as a function of phase sequence, and fit the equation to obtain the trend of change.

[0051] The phase sequence is numbered 1-24 according to the order of electromotive force from largest to smallest. Let the above numbers be the independent variable X and the electromotive force value be the dependent variable Y. Use graphing software to plot the curve of electromotive force changing with phase sequence, as shown below. Figure 5 As shown, the fitted equation is:

[0052] Y=0.0002x 3 -0.008x 2 +0.0536x+10.234

[0053] 4. Analyze the electrodynamic forces of busbar trunking under different phase sequence arrangements and provide suggestions.

[0054] The amplitude of the electrodynamic force varies with the phase sequence arrangement, as follows: Figure 6 Show. From Figure 6As can be seen from the diagram, the BANCPE phase sequence (shown in the black box in the figure) exhibits relatively small phase line electrodynamic forces. However, if any phase in the circuit experiences a large electrodynamic force, the entire circuit will be threatened. Therefore, in actual production of dense busbar trunking, the maximum value of each phase line electrodynamic force should be considered first. If the maximum electrodynamic forces are not significantly different, the arrangement with the smallest average electrodynamic force should be selected. The figure shows that when the phase sequence arrangements are ABNCPE, BNACPE, PEABNC, and PEBNAC (shown in the red box in the figure), the maximum electrodynamic force of the busbar trunking is approximately 9.73 N, which is 5.65% lower than the maximum electrodynamic force of the PEBACN arrangement (shown in the black box in the figure). By calculating and comparing the average electrodynamic forces of these four phase sequences, it can be found that the ABNCPE phase sequence has the smallest average electrodynamic force, at 5.5799 N. Therefore, ABNCPE is recommended as the optimal phase sequence arrangement.

[0055] Finally, it should be noted that the above embodiments are merely illustrative of the technical solutions of the present invention and not intended to limit it. Those skilled in the art should understand that modifications or equivalent substitutions can be made to the specific embodiments of the present invention, but such modifications or alterations are all within the scope of protection of the pending claims.

Claims

1. A method for optimizing the phase sequence arrangement of dense busbar trunking, characterized in that, Includes the following steps: Step S101: Determine the busbar trunking model and the arrangement of all its phase sequences, and use modeling software to establish the geometric model of the busbar trunking; Step S102: Import the model into the electromagnetic transient simulation software, establish a three-dimensional electromagnetic model of the dense busbar trunking by applying excitation and mesh generation, and solve and extract the electrodynamic forces of each phase line. Step S103: Based on the order of magnitude of the electromotive force, give the phase sequence arrangement order, draw the curve of the electromotive force changing with the phase sequence, and fit the equation to obtain the trend of change. Step S104: Compare the magnitude of the electrodynamic force of the busbar trunking under different arrangement methods, and give suggestions on the phase sequence arrangement of the busbar trunking based on the finite element simulation results and engineering practice.

2. The method for optimizing the phase sequence arrangement of dense busbar trunking according to claim 1, characterized in that, Step S101, which involves determining the busbar trunking model and its phase sequence arrangement, and establishing a geometric model of the busbar trunking using modeling software, specifically includes: Step S1011: Determine the busbar trunking model; Step S1012: If it is a three-phase four-wire system, the A, B, and C phases and the N line need to be arranged to determine the busbar phase sequence arrangement. The A, B, and C phases and the N line are all made of copper busbars of the same size wrapped with polyester film insulation. Arranging ABCN yields 24 arrangement combinations. Considering that the busbar arrangement according to ABCN is obtained by completely reversing the busbar arrangement according to NCBA, and the adjacent positions of the copper busbars in the busbar do not change, it is considered that these two arrangements are repeated. Therefore, arranging ABCN yields 12 non-repeating arrangement combinations, namely NABC, ANBC, ABNC, ABCN, NACB, ANCB, ACNB, ACBN, NBAC, BNAC, BANC, and BACN. If the busbar trunking model is a three-phase five-wire system, then the arrangement of the N and PE lines of the three phases A, B, and C needs to be determined to determine the phase sequence of the busbar trunking. Considering that the PE line needs to be grounded, there are two possible positions for the PE line, which are the leftmost and rightmost positions closest to the outer casing. The PE line is added to the 12 non-repeating arrangement combinations of the three-phase four-wire system, resulting in a total of 24 non-repeating arrangement combinations, namely NABCPE, ANBCPE, ABNCPE, ABCNPE, NACBPE, ANCBPE, ACNBPE, ACBNPE, NBACPE, BNACPE, BANCPE, BACNPE, PENABC, PEANBC, PEABNC, PEABCN, PENACB, PEANCB, PEACNB, PEACBN, PENBAC, PEBNAC, PEBANC, PEBACN. Step S1013: Establish the geometric model of the busbar trunking through the geometry module of the finite element software, and obtain the busbar trunking model with all phase sequence arrangements of this model through operations such as mirroring and changing the current excitation application order.

3. The method for optimizing the phase sequence arrangement of dense busbar trunking according to claim 1, characterized in that, In step S102, the model is imported into electromagnetic transient simulation software. A three-dimensional electromagnetic model of the dense busbar trunking is established by applying excitation and mesh generation. The electrodynamic forces of each phase line are solved and extracted. Specifically, this includes: Step S1021: Determine the electromagnetic transient simulation software, such as MAXWELL or similar computer-aided design software, select the transient analysis type, and establish a geometric model of the dense busbar trunking and a finite element model of the surrounding magnetic field distribution area based on the actual structural shape and size. Step S1022: Select the copper material built into the software as the copper conductor material of the busbar trunking; through the material manual, add the polyester film insulation layer and aluminum-magnesium alloy shell material of the busbar trunking, and determine the material parameters such as conductivity and relative permeability. Step S1023: Based on the characteristics of busbar operation, determine the maximum value of the periodic component, angular frequency, and initial phase angle of the three-phase current excitation. Apply current excitation to the copper conductors of phases A, B, and C, but do not apply current excitation to the copper conductors of the N and PE lines. Step S1024: Dense busbar trunking has a multi-layered structure. The copper conductor is the key part for generating and receiving magnetic field forces. Therefore, the copper conductor should be subjected to mesh refinement processing. The larger the volume of the computational domain, the more magnetic field distribution around the busbar trunking conductor, and the more accurate the electrodynamic calculation. Therefore, a suitable mesh should be used for the computational domain to ensure computational speed and accuracy. Step S1025: Add a "force" parameter to the copper conductor of the busbar trunking to calculate the electrodynamic force; set the calculation duration of the transient analysis, the calculation time of each step, calculate and export the electrodynamic force data.

4. The method for optimizing the phase sequence arrangement of dense busbar trunking according to claim 1, characterized in that, In step S103, the phase sequence is given according to the magnitude of the electromotive force, the curve of the electromotive force changing with the phase sequence is plotted, and the equation is fitted to obtain the trend of change. Specifically, this includes: Step S1031: Number the phase sequence arrangement according to the order of electromotive force from largest to smallest; Step S1032: Let the above number be the independent variable X and the electrodynamic force value be the dependent variable Y, and use plotting software to draw the curve of the electrodynamic force changing with the phase sequence; Step S1033: Select the polynomial fitting method to obtain the fitting equation.

5. The method for optimizing the phase sequence arrangement of dense busbar trunking according to claim 1, characterized in that, Step S104 compares the magnitude of the electrodynamic force of the busbar trunking under different arrangement methods, and provides suggestions on the phase sequence arrangement of the busbar trunking based on finite element simulation results and engineering practice. Specifically, this includes: Step S1041: Compare the maximum values ​​of the electrodynamic forces of each phase line of the busbar under different phase sequence arrangements; Step S1042: Select an arrangement where the maximum values ​​of the electromotive force are not significantly different, calculate the average electromotive force of each phase line, and compare them; Step S1043: Select the phase sequence arrangement with relatively large maximum electromotive force of each phase line and relatively small average electromotive force of each phase line as the optimal phase sequence arrangement combination for the busbar.

Images