CN113139321B - Calculation method and system for internal magnetic field distribution of direct-current transmission converter valve tower - Google Patents
Calculation method and system for internal magnetic field distribution of direct-current transmission converter valve tower Download PDFInfo
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Abstract
The invention relates to a calculation method and a system for magnetic field distribution in a direct-current transmission converter valve tower, which are used for decomposing time domain current into low-frequency sinusoidal current and high-frequency spike current; because the shielding effect of the nonmagnetic metal body on the low-frequency sinusoidal magnetic field is very weak, the calculation of the magnetic field generated by the low-frequency sinusoidal current flowing through the converter valve tower is equivalent to the calculation of the magnetic field in free space, and the required calculation time is very short; because the frequency of the high-frequency spike current in the converter valve is generally within 10MHz, the size of the valve tower can be regarded as an electric small size compared with the wavelength of the valve tower, and a quasi-static method is used for calculating a magnetic field generated by the high-frequency spike current flowing through the converter valve tower, so that the calculation speed is improved; the magnetic field after superposition of the first two parts is determined to be the magnetic field generated when the time-domain current flows through the converter valve tower, so that the magnetic field distribution inside the direct-current transmission converter valve tower is rapidly and accurately calculated.
Description
Technical Field
The invention relates to the technical field of electromagnetic field calculation, in particular to a method and a system for calculating magnetic field distribution in a direct-current transmission converter valve tower.
Background
In flexible dc power transmission converter valve towers, there are more sophisticated power electronics and complex operating conditions. When the converter valve works normally, the on and off of the IGBT are controlled through a special control strategy. In the on-off process, the IGBT generates more high-frequency electromagnetic disturbance, especially the MMC converter valve generates electromagnetic disturbance far larger than the traditional direct current converter valve, and the frequency is up to tens of MHz. There is therefore a need in engineering applications to study the magnetic field distribution inside the converter valve tower. In addition, in order to effectively suppress electromagnetic interference generated by the converter valve tower, shielding devices made of metal materials are often additionally arranged around the valve tower, so that the valve tower structure is further complicated. For such a complex structure, the analytical method is obviously not applicable to the calculation of the magnetic field distribution inside the converter valve tower; numerical simulation is insufficient in terms of model accuracy and calculation speed; the actual measurement method is limited by experimental conditions and has low efficiency.
Therefore, a method for rapidly and accurately calculating the internal magnetic field distribution of the direct-current transmission converter valve tower is needed.
Disclosure of Invention
The invention aims to provide a method and a system for calculating the magnetic field distribution in a direct-current transmission converter valve tower, so as to quickly and accurately calculate the magnetic field distribution in the direct-current transmission converter valve tower.
In order to achieve the above object, the present invention provides the following solutions:
A calculation method of magnetic field distribution inside a direct-current transmission converter valve tower, wherein a nonmagnetic metal shielding body is arranged around the converter valve tower, and the method comprises the following steps:
Acquiring a time domain current flowing through a converter valve tower, and decomposing the time domain current into a low-frequency sinusoidal current and a high-frequency spike current according to the waveform of the time domain current;
calculating a magnetic field generated by low-frequency sinusoidal current flowing through the converter valve tower as a first magnetic field;
Calculating a magnetic field generated by the high-frequency spike current flowing through the converter valve tower by using a quasi-static method to serve as a second magnetic field;
And determining the magnetic field obtained by superposing the first magnetic field and the second magnetic field as the magnetic field generated when the time domain current flows through the converter valve tower.
Further, the calculating the magnetic field generated by the low-frequency sinusoidal current flowing through the converter valve tower specifically comprises:
and calculating a magnetic field generated by the low-frequency sinusoidal current flowing through the converter valve tower when the nonmagnetic metal shielding body is not arranged by using the Pioshal law or electromagnetic simulation software according to the low-frequency sinusoidal current.
Further, the electromagnetic simulation software includes: COMSOL finite element simulation software, CST simulation software, and FEKO simulation software.
Further, the quasi-static method comprises: moment method, finite element method, time domain finite integration method and electromagnetic simulation.
A computing system for magnetic field distribution inside a dc transmission converter valve tower, around which a non-magnetic metal shield is disposed, the system comprising:
The current decomposition module is used for obtaining time-domain current flowing through the converter valve tower and decomposing the time-domain current into a low-frequency sinusoidal current and a high-frequency spike current according to the waveform of the time-domain current;
the first magnetic field calculation module is used for calculating a magnetic field generated by the low-frequency sinusoidal current flowing through the converter valve tower and taking the magnetic field as a first magnetic field;
the second magnetic field calculation module is used for calculating a magnetic field generated by the high-frequency spike current flowing through the converter valve tower by using a quasi-static method and taking the magnetic field as a second magnetic field;
And the magnetic field determining module is used for determining the magnetic field generated by the time-domain current when the time-domain current flows through the converter valve tower as the magnetic field generated by the superposition of the first magnetic field and the second magnetic field.
Further, the first magnetic field calculation module specifically includes:
And the magnetic field calculation sub-module is used for calculating the magnetic field generated by the low-frequency sinusoidal current flowing through the converter valve tower when the nonmagnetic metal shielding body is not arranged according to the low-frequency sinusoidal current by using the Pioshal law or electromagnetic simulation software.
Further, the electromagnetic simulation software includes: COMSOL finite element simulation software, CST simulation software, and FEKO simulation software.
Further, the quasi-static method comprises: moment method, finite element method, time domain finite integration method and electromagnetic simulation.
According to the specific embodiment provided by the invention, the invention discloses the following technical effects:
the invention provides a calculation method of magnetic field distribution in a direct-current transmission converter valve tower, which is used for decomposing time domain current into low-frequency sinusoidal current and high-frequency spike current; because the shielding effect of the nonmagnetic metal body on the low-frequency sinusoidal magnetic field is very weak, the calculation of the magnetic field generated by the low-frequency sinusoidal current flowing through the converter valve tower is equivalent to the calculation of the magnetic field in free space, and the required calculation time is very short; because the frequency of the high-frequency spike current in the converter valve is generally within 10MHz, the size of the valve tower can be regarded as an electric small size compared with the wavelength of the valve tower, and a quasi-static method is used for calculating a magnetic field generated by the high-frequency spike current flowing through the converter valve tower, so that the calculation speed is improved; the magnetic field after superposition of the first two parts is determined to be the magnetic field generated when the time-domain current flows through the converter valve tower, so that the magnetic field distribution inside the direct-current transmission converter valve tower is rapidly and accurately calculated.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions of the prior art, the drawings that are needed in the embodiments will be briefly described below, it being obvious that the drawings in the following description are only some embodiments of the present invention, and that other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.
FIG. 1 is a flow chart of a method for calculating the magnetic field distribution in a DC transmission converter valve tower provided by the invention;
Fig. 2 is a model view of an open-pore metal shielding plate according to embodiment 1 of the present invention;
FIG. 3 is a waveform diagram of the time-domain current waveform and the decomposed waveform provided in embodiment 1 of the present invention; fig. 3 (a) is a time-domain current waveform, fig. 3 (b) is a waveform of a low-frequency sinusoidal current, and fig. 3 (c) is a waveform of a high-frequency spike current;
FIG. 4 is a graph of the magnetic field generated by sinusoidal current provided in example 1 of the present invention; fig. 4 (a) is a magnetic field diagram generated by sinusoidal current at a measuring point z 1 =0.03 m, fig. 4 (b) is a magnetic field diagram generated by sinusoidal current at a measuring point z 2 =0.05 m, and fig. 4 (c) is a magnetic field diagram generated by sinusoidal current at a measuring point z 3 =0.1 m;
FIG. 5 is a magnetic field diagram generated by the high frequency spike current according to embodiment 1 of the present invention; fig. 5 (a) is a magnetic field diagram generated by high-frequency spike current at a measuring point z 1 =0.03 m, fig. 5 (b) is a magnetic field diagram generated by high-frequency spike current at a measuring point z 2 =0.05 m, and fig. 5 (c) is a magnetic field diagram generated by high-frequency spike current at a measuring point z 3 =0.1 m;
FIG. 6 is a graph showing the magnetic field profile generated by the current a provided in example 1 of the present invention; fig. 6 (a) is a magnetic field profile generated by a current a at a point z 1 =0.03 m, fig. 6 (b) is a magnetic field profile generated by a current a at a point z 2 =0.05 m, and fig. 6 (c) is a magnetic field profile generated by a current a at a point z 3 =0.1 m;
FIG. 7 is a waveform comparison chart of simulation results and calculation results provided in embodiment 1 of the present invention; fig. 7 (a) is a waveform comparison chart at a point z 1 =0.03 m, fig. 7 (b) is a waveform comparison chart at a point z 2 =0.05 m, and fig. 7 (c) is a waveform comparison chart at a point z 3 =0.1 m;
Fig. 8 is an equivalent model diagram of a modular multilevel converter provided in embodiment 2 of the present invention;
FIG. 9 is a schematic diagram of a simplified current loop inside the model provided in embodiment 2 of the present invention; fig. 9 (a) is an IGBT upper tube current path diagram, fig. 9 (b) is an IGBT lower tube current path diagram, fig. 9 (c) is an IGBT upper and lower tube total current path diagram, fig. 9 (d) is a high potential current path diagram, and fig. 9 (e) is a low potential current path diagram;
FIG. 10 is a time-domain current waveform provided in embodiment 2 of the present invention; fig. 10 (a) is a time domain current waveform diagram of an IGBT lower tube, fig. 10 (b) is a time domain current waveform diagram of an IGBT upper tube, fig. 10 (c) is a time domain current waveform diagram of an IGBT upper and lower tube, fig. 10 (d) is a low potential time domain current waveform diagram, and fig. 10 (e) is a high potential time domain current waveform diagram;
FIG. 11 is a waveform diagram of a sinusoidal current at power frequency provided in example 2 of the present invention; fig. 11 (a) is a power frequency sinusoidal current waveform diagram of an IGBT lower tube, fig. 11 (b) is a power frequency sinusoidal current waveform diagram of an IGBT upper tube, fig. 11 (c) is a power frequency sinusoidal current waveform diagram of an IGBT upper and lower tube, fig. 11 (d) is a power frequency sinusoidal current waveform diagram of a low potential, and fig. 11 (e) is a power frequency sinusoidal current waveform diagram of a high potential;
FIG. 12 is a waveform diagram of a high frequency spike current provided in embodiment 2 of the present invention; fig. 12 (a) is a high-frequency spike current waveform of an IGBT lower tube, fig. 12 (b) is a high-frequency spike current waveform of an IGBT upper tube, fig. 12 (c) is a high-frequency spike current waveform of an IGBT upper and lower tube, fig. 12 (d) is a low-potential high-frequency spike current waveform, and fig. 12 (e) is a high-potential high-frequency spike current waveform;
FIG. 13 is a graph showing the magnetic field profile generated by the current b provided in example 2 of the present invention; fig. 13 (a) is a magnetic field x-axis component profile generated by a current b, fig. 13 (b) is a magnetic field y-axis component profile generated by a current b, and fig. 13 (c) is a magnetic field z-axis component profile generated by a current b;
FIG. 14 is a graph showing the magnetic field profile generated by the current c provided in example 2 of the present invention; fig. 14 (a) is a magnetic field x-axis component profile generated by a current c, fig. 14 (b) is a magnetic field y-axis component profile generated by a current c, and fig. 14 (c) is a magnetic field z-axis component profile generated by a current c;
FIG. 15 is a graph showing the magnetic field profile generated by the current a provided in example 2 of the present invention; fig. 15 (a) is a magnetic field x-axis component profile generated by a current a, fig. 15 (b) is a magnetic field y-axis component profile generated by a current a, fig. 15 (c) is a magnetic field z-axis component profile generated by a current a, and fig. 15 (d) is a total magnetic field profile generated by a current a;
fig. 16 is a graph showing the magnetic field profile generated by the verification current a provided in example 2 of the present invention.
Detailed Description
The following description of the embodiments of the present invention will be made clearly and completely with reference to the accompanying drawings, in which it is apparent that the embodiments described are only some embodiments of the present invention, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
The invention aims to provide a method and a system for calculating the magnetic field distribution in a direct-current transmission converter valve tower, so as to quickly and accurately calculate the magnetic field distribution in the direct-current transmission converter valve tower.
In order that the above-recited objects, features and advantages of the present invention will become more readily apparent, a more particular description of the invention will be rendered by reference to the appended drawings and appended detailed description.
The invention provides a calculation method of magnetic field distribution in a direct-current transmission converter valve tower, as shown in fig. 1, wherein a non-magnetic metal shielding body is arranged around the converter valve tower, and the method comprises the following steps:
s101, obtaining a time domain current flowing through a converter valve tower, and decomposing the time domain current into a low-frequency sinusoidal current and a high-frequency spike current according to the waveform of the time domain current;
S102, calculating a magnetic field generated by a low-frequency sinusoidal current flowing through a converter valve tower as a first magnetic field;
s103, calculating a magnetic field generated by the high-frequency spike current flowing through the converter valve tower by using a quasi-static method, and taking the magnetic field as a second magnetic field;
s104, determining the magnetic field obtained by superposing the first magnetic field and the second magnetic field as the magnetic field generated when the time domain current flows through the converter valve tower.
The specific process is as follows:
step S101, decomposing a complex time domain current waveform with spike flowing through a converter valve tower into a low-frequency sinusoidal current and a high-frequency spike current.
In step S102, regarding the power frequency sinusoidal current (low frequency sinusoidal current), considering that the shielding effect of the non-magnetic metal body on the power frequency magnetic field is weak, the metal shielding body around the valve tower can be ignored, and only the magnetic field generated when the low frequency sinusoidal current flows through the converter valve without the shielding device is calculated, so that the problem of magnetic field calculation in free space is degraded. At this time, the spatial magnetic field can be directly calculated by the pioshal law or electromagnetic simulation software based on the current distribution, and the required calculation time is short.
The electromagnetic simulation software comprises: COMSOL finite element simulation software, CST simulation software, and FEKO simulation software.
In step S103, regarding the high-frequency spike current, regarding the metal shield around the valve tower as an ideal conductor material (PEC), the magnetic field generated by the high-frequency spike current when the shield material is PEC is calculated. Because the frequency of the high-frequency spike current in the converter valve is generally within 10MHz, the size of the valve tower can be regarded as an electric small size compared with the wavelength of the valve tower, so that the valve tower can be calculated by using a quasi-static method, meanwhile, PEC materials do not need to split grids internally, and the two aspects can greatly reduce the calculation complexity and the time requirement.
Because PEC materials are characterized in that the normal component of the magnetic field is 0 on the PEC surface, that is, the magnetic field lines do not pass through the PEC material, the quasi-static calculation can be performed by taking the normal component of the magnetic field on the PEC surface as a boundary condition, and the quasi-static method comprises the following steps: moment method, finite element method, time domain finite integration method and electromagnetic simulation. Taking COMSOL finite element simulation software as an example, the COMSOL self-contained magnetic insulation boundary condition can be additionally arranged on the PEC surface aiming at PEC materials, and mesh division is only carried out on the surface and the outer side of the shielding body, so that the defects of low calculation speed and inaccurate calculation caused by the fact that the metal shielding material is required to be divided into precise meshes in the prior art are overcome, and time and memory can be saved on the premise of ensuring accuracy.
Quasi-static methods refer to computational or simulation methods under quasi-static conditions, not a specific method name, but rather a precondition. Quasi-static conditions refer to the model size being much smaller than the wavelength of the frequency of investigation (size < wavelength/(2 pi)).
And step S104, superposing the magnetic fields obtained in the step S102 and the step S103 together to obtain the magnetic field generated when the sinusoidal current with the high-frequency spike flows in the converter valve tower.
According to the invention, for low-frequency power frequency sinusoidal current, the problem of magnetic field calculation of degradation into free space caused by the fact that the shielding effect of a non-magnetic metal body on a power frequency magnetic field is very weak and the metal shielding body around a valve tower can be ignored, and only the magnetic field generated when the low-frequency sinusoidal current flows through a converter valve without a shielding device is calculated. At this time, the spatial magnetic field can be directly calculated by the pioshal law based on the current distribution, and the calculation time required is short. And regarding the high-frequency spike current, regarding the metal shielding body around the valve tower as an ideal conductor material (PEC), calculating a magnetic field generated by the high-frequency spike current when the shielding material is the PEC. Because the frequency of the high-frequency spike current in the converter valve is generally within 10MHz, the size of the valve tower can be regarded as an electric small size compared with the wavelength of the valve tower, so that the valve tower can be calculated by using a quasi-static method, meanwhile, PEC materials do not need to split grids internally, and the two aspects can greatly reduce the calculation complexity and the time requirement. And superposing the results obtained by calculation of the two sub-models to obtain the internal magnetic field distribution of the converter valve tower under the actual metal material shielding device when the current flows through the complex waveform (power frequency sine superposition high-frequency spike). And, the speed of calculating the two sub-models is far faster than that of directly calculating the original model.
Example 1
Fig. 2 shows a simple embodiment of the method: and opening the metal shielding plate model. The time domain current I flows in the annular transmitting antenna with the radius r, the thickness of the metal shielding plate is t, a round hole with the radius a is arranged in the center, the round hole and the annular antenna are coaxially arranged, and the magnetic field waveform at the measuring point P of the area above the shielding plate is solved. The parameters in this example are set ：r＝6cm,z0＝5cm,t＝0.5mm,a＝1.5cm,z1＝0.03m,z2＝0.05m,z3＝0.1m(z1、z2、z3 to three different height points on the z-axis).
Step 1: the time domain current waveform with spike (current a) is decomposed into a low frequency sinusoidal current (current b) and a high frequency spike current (current c), and the result is shown in fig. 3, with the ordinate being the current magnitude (a).
Step 2: the magnetic field generated by the sinusoidal current when the shielding device is not added is calculated in a simulation way. The method comprises the following steps: unshielded device + current b, the result is shown in fig. 4 with the magnetic field strength (a/m) on the ordinate. The calculation is directly performed by using CST simulation software, and a CST microwave working chamber module is used. CST is based on the time domain finite integration method. Fig. 4 (a) shows the magnetic field generated by sinusoidal current at the z 1 =0.03 m measurement point, fig. 4 (b) shows the magnetic field generated by sinusoidal current at the z 2 =0.05 m measurement point, and fig. 4 (c) shows the magnetic field generated by sinusoidal current at the z 3 =0.1 m measurement point.
Step 3: and (3) simulating and calculating a magnetic field generated by high-frequency spike current when the shielding material is PEC. The method comprises the following steps: PEC mask + current c, the result is shown in fig. 5 with the magnetic field strength (a/m) on the ordinate. Fig. 5 (a) shows a magnetic field generated by a high-frequency spike current at a point z 1 =0.03 m, fig. 5 (b) shows a magnetic field generated by a high-frequency spike current at a point z 2 =0.05 m, and fig. 5 (c) shows a magnetic field generated by a high-frequency spike current at a point z 3 =0.1 m.
Step 4: the magnetic fields obtained in the step 2 and the step 3 are superimposed together, namely, the magnetic field generated by the current a is equivalently obtained, and the result is shown in fig. 6, and the ordinate is the magnetic field intensity (A/m). Fig. 6 (a) shows the magnetic field generated by the current a at the z 1 =0.03 m measuring point, fig. 6 (b) shows the magnetic field generated by the current a at the z 2 =0.05 m measuring point, and fig. 6 (c) shows the magnetic field generated by the current a at the z 3 =0.1 m measuring point.
And (3) verification: the simulation calculates the metallic shield + current a, compared to the waveform of fig. 6, and the result is shown in fig. 7 with the magnetic field strength (a/m) on the ordinate. As can be seen from fig. 7, the two curves substantially coincide, i.e. the result re-superposition obtained with the submodel using the method described above is substantially identical to the result of the direct calculation. Fig. 7 (a) shows a waveform comparison chart at a point z 1 =0.03 m, fig. 7 (b) shows a waveform comparison chart at a point z 2 =0.05 m, and fig. 7 (c) shows a waveform comparison chart at a point z 3 =0.1 m.
The consistency of the results of the superposition of the original model and the simplified model of example 1 shown in fig. 7 proves that the method of decomposing the current first, then adopting different sub-models for calculating different types of current, and finally superposing the results of the sub-models has certain accuracy.
Example 2
Fig. 8 shows an equivalent model of a modular-multilevel-converter (MMC), with a simplified current loop inside and a non-magnetic metal shield outside.
In practice, the modularized multi-level converter has a complex structure, the switching-on and switching-off working conditions of the switch are complex, and the interference is difficult to accurately calculate, so that the operation working conditions of the modularized multi-level converter are difficult to accurately simulate. Fig. 9 is a schematic diagram of a simplified current loop inside the model. In the equivalent loop, the current paths and the positions of the sections can be respectively equivalent to the upper tube current, the lower tube current, the total upper tube current and the lower tube current of the IGBT, the high potential current and the low potential current of the IGBT. Fig. 9 (a) is an IGBT upper tube current path diagram, fig. 9 (b) is an IGBT lower tube current path diagram, fig. 9 (c) is an IGBT upper and lower tube total current path diagram, fig. 9 (d) is a high potential current path diagram, and fig. 9 (e) is a low potential current path diagram. The light gray lines in each of fig. 9 (a) - (e) are current paths for the respective figures.
Step 1: the time-domain current waveform (current a) of the current flowing through each part with the spike is decomposed into two parts of a power frequency sinusoidal current (current b) and a high-frequency spike current (current c), and the results are shown in fig. 10-12.
Step 2: and calculating a magnetic field generated by the power frequency sinusoidal current when the shielding device is not additionally arranged.
When no outer shielding is adopted, the unit current with the amplitude of 1A is added to the upper tube current section of the simplified model in fig. 8, the current of other current sections is set to be zero, and the magnetic field at the obtained measuring point is recorded asSimilarly, the lower tube current section, the upper tube and lower tube total current section, the high potential current section and the low potential current section are respectively and independently added with unit currents, when a certain part of current sections are added with the unit currents, other parts of currents are set to be zero, and magnetic fields measured at measuring points are respectively recorded as follows: /(I)
The results are linearly superposed, and the total magnetic field generated by the low-frequency sinusoidal current at the measuring point when the shielding is not needed can be obtained according to the following formula, wherein H is a vector magnetic field, and I is the low-frequency sinusoidal current in fig. 11:
Η1＝Η1 Upper part I Upper part +Η1 Lower part(s) I Lower part(s) +Η1 Upper part + Lower part(s) I Upper part + Lower part(s) +Η1 High potential I High potential +Η1 Low potential I Low potential
Fig. 13 shows that: the magnetic field H 1 generated at the measurement point without shielding + current b.
Step 3: and calculating a magnetic field generated by the high-frequency spike current when the shielding material is PEC. The PEC shielding plate is additionally arranged on the outer side of the model adopted in the step, and the rest is similar to the step 2, and unit currents (when one of the currents is independently additionally arranged, the currents of other current segments are set to be zero) are respectively and independently arranged in the upper tube current segment, the lower tube current segment, the upper tube total current segment, the lower tube total current segment, the high potential current segment and the low potential current segment. The magnetic fields measured at the measuring points are respectively noted as: The results are linearly superposed, and the total magnetic field generated by the low-frequency sinusoidal current at the measuring point when the shielding is not needed can be obtained according to the following formula, wherein H is a vector, and I' is the high-frequency spike current in fig. 12:
Η2＝Η2 Upper part I′ Upper part +Η2 Lower part(s) I′ Lower part(s) +Η2 Upper part + Lower part(s) I′ Upper part + Lower part(s) +Η2 High potential I′ High potential +Η2 Low potential I′ Low potential
fig. 14 shows that: PEC shields the magnetic field H 1 generated at the measurement point in the case of a +current c.
Step 4: superposing the magnetic fields obtained in the step 2 and the step 3 to obtain superposition values of magnetic field components in x, y and z directions respectively, and then passing through a formulaThe final total magnetic field at the location can be calculated and the result is shown in fig. 15.
And (3) verification: fig. 16 shows the calculation result of the MMC model by dividing the current path into microelements, respectively calculating the complex current wave acting on each section of microelements, and generating magnetic fields at the measuring points to be superimposed together, namely directly calculating the situation of 'metal shielding + current a'. According to the method, the model is required to be subjected to detail subdivision, and then calculation is carried out section by section, and particularly, more time is required to process the metal material grids. The consistency of the final results of fig. 16 and 15 indicates that: the total magnetic field obtained by calculation through the sub-model superposition method is more accurate, and the calculation time is greatly saved.
Example 2 better demonstrates the advantages of the method of calculating post-superposition using two sub-models, respectively, described above. For a modularized multi-level converter with a complex structure, if a current loop is directly micronized and a metal framework is split into fine grids for calculation, more than ten hours are needed; and decomposing the current, establishing the submodel, and respectively calculating and linearly superposing the submodel according to the magnetic field generated by the unit current, wherein the method only needs a few minutes. In addition, for the model in the embodiment, on the premise of unchanged model size, the magnetic field generated when unit current is added to each current segment in the submodel The current is unchanged, so that when the magnetic field under the condition of different complex current waveforms is calculated, the existing calculation result H of the submodel under the condition of unit current can be combined with different current to carry out linear superposition, and the calculation time can be greatly saved.
The invention also provides a calculation system of the magnetic field distribution inside the direct-current transmission converter valve tower, a non-magnetic metal shielding body is arranged around the converter valve tower, and the system comprises:
The current decomposition module is used for obtaining the time domain current flowing through the converter valve tower and decomposing the time domain current into a low-frequency sinusoidal current and a high-frequency spike current according to the waveform of the time domain current;
the first magnetic field calculation module is used for calculating a magnetic field generated by the low-frequency sinusoidal current flowing through the converter valve tower and taking the magnetic field as a first magnetic field;
the second magnetic field calculation module is used for calculating a magnetic field generated by the high-frequency spike current flowing through the converter valve tower by using a quasi-static method and taking the magnetic field as a second magnetic field;
And the magnetic field determining module is used for determining the magnetic field obtained by superposing the first magnetic field and the second magnetic field as the magnetic field generated when the time-domain current flows through the converter valve tower.
The first magnetic field calculation module specifically comprises:
and the magnetic field calculation sub-module is used for calculating the magnetic field generated by the low-frequency sinusoidal current flowing through the converter valve tower when the nonmagnetic metal shielding body is not arranged according to the low-frequency sinusoidal current by using the Pioshal law or electromagnetic simulation software.
The electromagnetic simulation software comprises: COMSOL finite element simulation software, CST simulation software, and FEKO simulation software.
The quasi-static method comprises the following steps: moment method, finite element method, time domain finite integration method and electromagnetic simulation.
In the present specification, each embodiment is described in a progressive manner, and each embodiment is mainly described in a different point from other embodiments, and identical and similar parts between the embodiments are all enough to refer to each other. For the system disclosed in the embodiment, since it corresponds to the method disclosed in the embodiment, the description is relatively simple, and the relevant points refer to the description of the method section.
The principles and embodiments of the present invention have been described herein with reference to specific examples, the description of which is intended only to assist in understanding the methods of the present invention and the core ideas thereof; also, it is within the scope of the present invention to be modified by those of ordinary skill in the art in light of the present teachings. In view of the foregoing, this description should not be construed as limiting the invention.
Claims (8)
1. The method for calculating the magnetic field distribution inside the direct-current transmission converter valve tower is characterized in that a non-magnetic metal shielding body is arranged around the converter valve tower, and the method comprises the following steps:
Acquiring a time domain current flowing through a converter valve tower, and decomposing the time domain current into a low-frequency sinusoidal current and a high-frequency spike current according to the waveform of the time domain current;
Calculating a magnetic field generated by low-frequency sinusoidal current flowing through the converter valve tower as a first magnetic field; for the low-frequency sinusoidal current, a metal shielding body around the valve tower is ignored, and only a magnetic field generated when the low-frequency sinusoidal current flows through the converter valve without the shielding device is calculated, so that the problem of magnetic field calculation of free space is solved;
Calculating a magnetic field generated by the high-frequency spike current flowing through the converter valve tower by using a quasi-static method to serve as a second magnetic field; regarding high-frequency spike current, regarding a metal shielding body around a valve tower as an ideal conductor material PEC, and calculating a magnetic field generated by the high-frequency spike current when the shielding material is the PEC;
And determining the magnetic field obtained by superposing the first magnetic field and the second magnetic field as the magnetic field generated when the time domain current flows through the converter valve tower.
2. The method for calculating the magnetic field distribution inside the dc transmission converter valve tower according to claim 1, wherein the calculating the magnetic field generated by the low-frequency sinusoidal current flowing through the converter valve tower specifically comprises:
and calculating a magnetic field generated by the low-frequency sinusoidal current flowing through the converter valve tower when the nonmagnetic metal shielding body is not arranged by using the Pioshal law or electromagnetic simulation software according to the low-frequency sinusoidal current.
3. The method for calculating the internal magnetic field distribution of the direct-current transmission converter valve tower according to claim 2, wherein the electromagnetic simulation software comprises: COMSOL finite element simulation software, CST simulation software, and FEKO simulation software.
4. The method for calculating the internal magnetic field distribution of the direct-current transmission converter valve tower according to claim 1, wherein the quasi-static method comprises: moment method, finite element method, time domain finite integration method and electromagnetic simulation.
5. A computing system for magnetic field distribution inside a dc transmission converter valve tower, wherein a non-magnetic metal shield is disposed around the converter valve tower, the system comprising:
The current decomposition module is used for obtaining time-domain current flowing through the converter valve tower and decomposing the time-domain current into a low-frequency sinusoidal current and a high-frequency spike current according to the waveform of the time-domain current;
The first magnetic field calculation module is used for calculating a magnetic field generated by the low-frequency sinusoidal current flowing through the converter valve tower and taking the magnetic field as a first magnetic field; for the low-frequency sinusoidal current, a metal shielding body around the valve tower is ignored, and only a magnetic field generated when the low-frequency sinusoidal current flows through the converter valve without the shielding device is calculated, so that the problem of magnetic field calculation of free space is solved;
The second magnetic field calculation module is used for calculating a magnetic field generated by the high-frequency spike current flowing through the converter valve tower by using a quasi-static method and taking the magnetic field as a second magnetic field; regarding high-frequency spike current, regarding a metal shielding body around a valve tower as an ideal conductor material PEC, and calculating a magnetic field generated by the high-frequency spike current when the shielding material is the PEC;
And the magnetic field determining module is used for determining the magnetic field generated by the time-domain current when the time-domain current flows through the converter valve tower as the magnetic field generated by the superposition of the first magnetic field and the second magnetic field.
6. The system for calculating the magnetic field distribution inside the dc transmission converter valve tower according to claim 5, wherein the first magnetic field calculation module specifically comprises:
And the magnetic field calculation sub-module is used for calculating the magnetic field generated by the low-frequency sinusoidal current flowing through the converter valve tower when the nonmagnetic metal shielding body is not arranged according to the low-frequency sinusoidal current by using the Pioshal law or electromagnetic simulation software.
7. The system for calculating the magnetic field distribution inside a dc transmission converter valve tower according to claim 6, wherein the electromagnetic simulation software comprises: COMSOL finite element simulation software, CST simulation software, and FEKO simulation software.
8. The system for calculating the internal magnetic field distribution of a dc power transmission converter valve tower of claim 5, wherein said quasi-static method comprises: moment method, finite element method, time domain finite integration method and electromagnetic simulation.
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Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2008140924A1 (en) * | 2007-05-09 | 2008-11-20 | Frederick William Klatt | Brushless multiphase self-commutation control and related inventions |
| CN108680813A (en) * | 2018-08-21 | 2018-10-19 | 北京经纬恒润科技有限公司 | A kind of electromagnetic interference modeling and simulating method and device |
| CN109508480A (en) * | 2018-10-23 | 2019-03-22 | 华中科技大学 | A kind of construction low-frequency harmonics electric current calculates the semi-analytic method of motor high frequency electromagnetic force |
| CN110362937A (en) * | 2019-07-19 | 2019-10-22 | 华北电力大学 | A kind of modularization multi-level converter electromagnetical transient emulation method and system |
| JP2020154560A (en) * | 2019-03-19 | 2020-09-24 | 学校法人同志社 | Electromagnetic field simulator and electromagnetic field analysis method |
-
2021
- 2021-05-14 CN CN202110526645.9A patent/CN113139321B/en active Active
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2008140924A1 (en) * | 2007-05-09 | 2008-11-20 | Frederick William Klatt | Brushless multiphase self-commutation control and related inventions |
| CN108680813A (en) * | 2018-08-21 | 2018-10-19 | 北京经纬恒润科技有限公司 | A kind of electromagnetic interference modeling and simulating method and device |
| CN109508480A (en) * | 2018-10-23 | 2019-03-22 | 华中科技大学 | A kind of construction low-frequency harmonics electric current calculates the semi-analytic method of motor high frequency electromagnetic force |
| JP2020154560A (en) * | 2019-03-19 | 2020-09-24 | 学校法人同志社 | Electromagnetic field simulator and electromagnetic field analysis method |
| CN110362937A (en) * | 2019-07-19 | 2019-10-22 | 华北电力大学 | A kind of modularization multi-level converter electromagnetical transient emulation method and system |
Non-Patent Citations (7)
| Title |
|---|
| Low Frequency Magnetic Shielding Effectiveness of a Conducting Plate With Periodic Apertures;Bai, Wanxin and Ning, Feng and Yang, Xiaochen and Jiao, Chongqing and Chen, Longlong;IEEE Transactions on Electromagnetic Compatibility;20200501;第63卷(第1期);30-37 * |
| Shielding Effectiveness Analysis of the Conducting Spherical Shell With a Circular Aperture Against Low Frequency Magnetic Fields;Yang, Xiaochen and Zhang, Zhixin and Ning, Feng and Jiao, Chongqing and Chen, Longlong;IEEE Access;20200420;第8卷;79844-79850 * |
| VSC-HVDC换流系统辐射电磁场计算及其影响因素分析;孙海峰;杜林森;梁贵书;蒋剑;;华北电力大学学报(自然科学版);20151130(第06期);16-23 * |
| 刘兵 ; 阮江军 ; 韩海宏 ; 余世峰 ; 吴田 ; .柔性直流输电系统电磁环境分析.高电压技术.2009,第35卷(第11期),2747-2752. * |
| 换流站阀厅电磁骚扰强度的计算分析;赵志斌;崔翔;王琦;;高电压技术;20100331(第03期);643-648 * |
| 柔性直流输电系统电磁环境分析;刘兵;阮江军;韩海宏;余世峰;吴田;;高电压技术;20091130;第35卷(第11期);2747-2752 * |
| 模块化多电平换流阀系统天线模型及其辐射电磁骚扰特性分析;孙海峰;杜林森;梁贵书;;中国电机工程学报;20160205(第03期);879-888 * |
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