CN113361049A - Transformer bias current calculation method based on subway near-zone earth and power grid model - Google Patents

Transformer bias current calculation method based on subway near-zone earth and power grid model Download PDF

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CN113361049A
CN113361049A CN202110412261.4A CN202110412261A CN113361049A CN 113361049 A CN113361049 A CN 113361049A CN 202110412261 A CN202110412261 A CN 202110412261A CN 113361049 A CN113361049 A CN 113361049A
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subway
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CN113361049B (en
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陈璐
黄华
王龙飞
吴天逸
苏磊
刘春明
赵丹丹
刘文琳
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North China Electric Power University
State Grid Shanghai Electric Power Co Ltd
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State Grid Shanghai Electric Power Co Ltd
East China Power Test and Research Institute Co Ltd
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Abstract

The invention relates to a method for calculating bias current of a transformer based on a subway near-zone earth and power grid model, which comprises the steps of calculating the size of stray current through a resistance network model, analyzing the change of the surrounding ground potential caused by the stray current based on a ground resistivity model, and finally establishing an urban 220kV transformer network topology model to obtain the relation of the change of the current of a neutral point of the transformer along with time. The invention provides a calculation method for quantitatively calculating the bias current of a 220kV transformer in a power grid near a subway line for researching the correlation between the phenomenon of the stray current of the subway and the bias current of the 220kV transformer in the urban network, and the method is beneficial to analyzing the influence of the stray current of the subway on the transformer and overcoming the defects of a model and a method for calculating the bias current of the 220kV transformer in the urban network near the subway line in the prior art.

Description

Transformer bias current calculation method based on subway near-zone earth and power grid model
Technical Field
The invention relates to the field of urban power grids and transformers, in particular to a method for calculating bias current of a 220kV transformer based on a subway near-region earth and power grid model.
Background
With the continuous development of urban construction, urban rail transit is larger and larger, and becomes the most convenient scheme for determining the trip of citizens. However, because urban subways or light rails mostly adopt a direct current traction power supply mode, the rails are not completely insulated from the ground, and direct current leaks from the subway rails to the ground in the running process of a subway train, so that so-called subway direct current stray current is formed. The stray direct current can flow into the transformer winding through the grounding grid of the urban power grid transformer substation, the direct current magnetic biasing saturation of the transformer is caused, the main transformer vibration and the noise are aggravated, the temperature of the transformer core and the clamping piece is increased, and the serious direct current magnetic biasing can cause the transformer damage accident. The influence of the direct current stray current on the bias of the 220kV transformer of the urban network is a problem to be researched.
In the prior art, the harmful influence of direct-current stray current on corrosion of underground pipelines is researched, and the stray current under unilateral and bilateral power supply modes is calculated by modeling the subway stray current. Based on the purpose, in the prior art, the calculation or analysis of the static distribution model of the stray current of the single-side power supply and the double-side power supply is not researched, but the influence of the stray current of the subway on an underground metal pipeline or other metal facilities is mainly proved, but research literature reports of the establishment of a subway near-region earth and power grid model and the calculation of the bias current of a 220kV transformer of the urban network are not found. The urban network transformer is a power network area which is most affected by the bias current, the calculation complexity is higher, and the urban network transformer becomes a defect which cannot be solved by the prior art. Therefore, the invention provides a 220kV transformer bias current calculation method based on a subway near-zone earth and power grid model, which is used for solving the problems in the prior art.
Disclosure of Invention
Stray current generated during the operation of the subway can affect the electromagnetic environment nearby the subway, and further affect a 220kV transformer of a power grid around the subway. In order to analyze the influence of stray current on the direct current magnetic bias of the transformer, the invention provides that the size of the stray current is calculated by establishing a resistance network model, then the change of the surrounding ground potential caused by the stray current is analyzed based on a ground resistivity model, and finally, an urban network 220kV transformer network topology model is established, so that the relation of the change of the current of the neutral point of the transformer along with the time is obtained. The quantitative analysis method is provided for researching the correlation between the stray current of the subway and the bias current phenomenon of the urban network 220kV transformer and calculating the bias current of the urban network 220kV transformer near the subway, is beneficial to analyzing the influence of the stray current of the subway on the transformer and overcomes the defect that the calculated bias current of the subway near-region urban network 220kV transformer is lacked in the prior art.
In order to achieve the above purposes, the technical scheme adopted by the invention is as follows:
a method for calculating bias current of a transformer based on a subway near-zone earth and power grid model comprises the following steps:
step 1: establishing a resistance network model, and calculating stray current leaked from the steel rail and flowing into the ground during the operation of the subway through the resistance network model;
step 2: establishing a three-dimensional resistivity model of the earth according to the earth electrical property and the construction data thereof, and calculating the ground potential of the subway near-region transformer substation by using the three-dimensional resistivity model of the earth;
and step 3: analyzing influence factors of power grid bias current, and simplifying data and parameters such as a power grid structure, lead resistance, transformer wiring, winding resistance and the like by using a GIC-Benchmark method to obtain a simplified transformer substation and power supply line bias current equivalent circuit;
and 4, step 4: and (3) establishing a power grid magnetic bias current model based on the GIC-Benchmark method and the equivalent circuit obtained in the step (3), and calculating the direct current magnetic bias current of each transformer substation neutral point of the power grid.
On the basis of the scheme, in the step 1, the circulation path of the stray current leaks outwards from the rail at the train wheel, enters the ground through the rail track bed structure and the drainage network, and flows back to the transformer substation from the ground.
On the basis of the scheme, the specific steps of the step 1 are as follows:
firstly, considering the condition that a pipeline and a track are distributed in parallel, simplifying the track, a drainage network and the ground into laminated resistors, establishing a resistor network model, and then calculating to obtain stray current when a train runs to a certain position according to resistance data and the resistor network model;
the train is set to travel from location 1 to location 2, resulting in stray current flowing from rail leakage into the ground during operation of the train.
On the basis of the scheme, KCL and KVL equations of the resistance network model are respectively as follows:
Figure BDA0003024633500000031
Figure BDA0003024633500000032
in the formula:
Figure BDA0003024633500000033
representing the current on the track, RGRepresenting the longitudinal resistance of the rail, RPIn order to drain the longitudinal resistance of the wire,
Figure BDA0003024633500000034
is the current of the drainage network, g1Is the transition conductance of the rail and the drainage network, g2Is the transition conductance of the drainage network to earth, u1(x) Representing the voltage on the transition conductance of the track and the drainage network, u2(x) Representing the voltage on the transition conductance of the drainage network to earth;
assuming that the total stray current generated when the train runs to a distance of x meters from the transformer substation is IscOf stray current IscThe calculation formula of (2) is as follows:
Figure BDA0003024633500000035
Iscnamely the stray current when the train runs on the whole line,
Figure BDA0003024633500000036
which is representative of the current on the track,
Figure BDA0003024633500000037
is the current of the drainage network, I is the current through the train, Isc1、isc2Representing the stray current of each micro-element.
On the basis of the scheme, the specific steps of the step 2 are as follows:
supposing that the subway normally operates, stray current flows into the ground, and the stray current entering the ground is taken as a driving current source of the bias current of the transformer in the near area of the subway;
and deducing and solving field equations near the rails based on the Maxwell equation set, and expressing the earth potential distribution rule by using the field equations.
On the basis of the above scheme, maxwell differential equations of the stray current are shown in formulas (4) and (5) in a basic form, and auxiliary equations are shown in formulas (6) and (7):
Figure BDA0003024633500000038
Figure BDA0003024633500000041
Figure BDA0003024633500000042
Figure BDA0003024633500000043
wherein the content of the first and second substances,
Figure BDA0003024633500000044
represents del operator, → is the vector sign, and E is the electric field strength (V/m); j is the current density (A/m)2)；ρvIs the bulk charge density (C/m)3) (ii) a σ is the conductivity (S/m); u is a scalar potential (V) and t is time;
based on the expression, the field quantity U to be solved is used to describe two types of equations of the current field, wherein the two types of equations are Laplace equations without current sources, as shown in formula (8), and Poisson equations with current sources, as shown in formula (9):
Figure BDA0003024633500000045
Figure BDA0003024633500000046
on the basis of the scheme, the specific steps of the step 3 are as follows:
analyzing the influence factors of the bias current in the power grid when the subway normally operates;
and considering the influence of the influence factor of the bias current, simplifying data and parameters such as a power grid structure, wire resistance, transformer wiring, winding resistance and the like according to a GIC-Benchmark method to obtain a simplified bias current equivalent circuit of the transformer substation and the power supply line.
On the basis of the scheme, calculating the bias current by adopting a KVL method;
the KVL equation system for calculating the bias current is:
Figure BDA0003024633500000047
wherein n is the number of nodes, I0For the distribution of the stray current into the ground, RiiIs point i self-admittance, i is 1,2, …, n, RijIs the mutual admittance of point i and point j, j is 1,2, …, n, uiAnd IiIs the potential and current of the earth point i, R0iIs the equivalent ground resistance of the substation.
Drawings
The invention has the following drawings:
FIG. 1 is a schematic diagram of a double-side power supply circuit model in the earth potential model;
FIG. 2 is a diagram of a circuit micro-element model;
FIG. 3 is a schematic diagram of an equivalent circuit for calculating a grid bias current;
FIG. 4 is a geographic view of a metro system in a certain city;
FIG. 5 is a graph illustrating the variation of the full-line stray current with time;
FIG. 6 is a schematic diagram of a potential variation curve along the subway line;
FIG. 7 is a schematic diagram of the bias current at the transformer neutral point of substation 1;
fig. 8 shows a schematic diagram of the bias current of the transformer neutral point of substation 2.
Detailed Description
The present invention is described in further detail below with reference to figures 1-8.
A method for calculating bias current of a transformer based on a subway near-zone earth and power grid model specifically comprises the following steps:
step 1: establishing a resistance network model, and calculating stray current leaked from the steel rail and flowing into the ground during the operation of the subway through the resistance network model;
step 2: establishing a three-dimensional resistivity model of the earth according to the earth electrical property and the construction data thereof, and calculating the ground potential of the subway near-region transformer substation by using the three-dimensional resistivity model of the earth;
and step 3: analyzing influence factors of power grid bias current, and simplifying data and parameters such as a power grid structure, lead resistance, transformer wiring, winding resistance and the like by using a GIC-Benchmark method to obtain a simplified transformer substation and power supply line bias current equivalent circuit;
and 4, step 4: and (3) establishing a power grid magnetic bias current model based on the GIC-Benchmark method and the equivalent circuit obtained in the step (3), and calculating the direct current magnetic bias current of each transformer substation neutral point of the power grid.
In the step 1, the circulation path of the stray current is that the stray current leaks outwards from the track at the train wheels, enters the ground through the track ballast bed structure and the drainage network, and flows back to the transformer substation from the ground.
Further, the specific steps of step 1 are:
firstly, considering the condition that a pipeline and a track are distributed in parallel, simplifying the track, a drainage network and the ground into laminated resistors, establishing a resistor network model, and then calculating to obtain stray current when a train runs to a certain position according to resistance data and the resistor network model;
the train is set to travel from location 1 to location 2, resulting in stray current flowing from rail leakage into the ground during operation of the train.
Specifically, the KCL and KVL equations of the resistance network model are respectively:
Figure BDA0003024633500000061
Figure BDA0003024633500000062
in the formula:
Figure BDA0003024633500000063
representing the current on the track, RGRepresenting the longitudinal resistance of the rail, RPIn order to drain the longitudinal resistance of the wire,
Figure BDA0003024633500000064
is the current of the drainage network, g1Is the transition conductance of the rail and the drainage network, g2Is the transition conductance of the drainage network to earth, u1(x) Representing the voltage on the transition conductance of the track and the drainage network, u2(x) Representing the voltage on the transition conductance of the drainage network to earth;
assuming that the total stray current generated when the train runs to a distance of x meters from the transformer substation is IscOf stray current IscThe calculation formula of (2) is as follows:
Isc＝∑(isc1+isc2)＝I-iG1-iP1 (3)
Iscnamely the stray current when the train runs on the whole line,
Figure BDA0003024633500000065
which is representative of the current on the track,
Figure BDA0003024633500000066
is the current of the drainage network, I is the current through the train, Isc1、isc2Representing the stray current of each micro-element.
Specifically, a three-layer resistance network model is adopted as a train leakage current model, a DC1500V power supply overhead contact network is adopted for a subway system to supply power on the two sides, and traveling rails flow back. In order to reduce stray current leakage, measures such as arranging a gasket and insulating rubber are adopted to increase the rail-ground transition resistance; meanwhile, a drainage net is arranged in concrete below the track to recover stray current. Therefore, the subway stray current circulation path is from the rail to the outside at the wheel of the trainAnd the leakage enters the ground through the track bed structure and the drainage network and flows back to the transformer substation from the ground. According to the stray current leakage path, considering the parallel distribution condition of the pipeline and the track, simplifying the track, the drainage network and the ground into laminated resistors, and connecting different layers by using transition resistors. The stray current flow path can be regarded as a current loop of the rail-drainage network-earth parallel to each other. The distribution of the established three-layer resistance network model is shown in figure 1. In the figure, I1And I2For the magnitude of the current through the train's equivalent resistance, I3And I4For the magnitude of the current flowing through the train track, I5And I6For the magnitude of the current through the grid, I7And I8The magnitude of the leakage current. Since the subway line, the drainage network and the ground resistance are all uniform transmission line models, the circuit model should be differentiated, and a micro-element model of the circuit can be obtained as shown in fig. 2. According to the formulas (1), (2) and (3), the total stray current when the train runs to a certain position can be calculated, and the condition of the stray current entering the ground when the train runs from the position 1 to the position 2 can be obtained by arranging the train to run from the position 1. Assuming that the total stray current I generated when the train travels x meters from the substationscThe stray current value is defined by the stray current, i.e., equation (3).
Further, the specific steps of step 2 are:
supposing that the subway normally operates, stray current flows into the ground, and the stray current entering the ground is taken as a driving current source of the bias current of the transformer in the near area of the subway;
and deducing and solving field equations near the rails based on the Maxwell equation set, and expressing the earth potential distribution rule by using the field equations.
On the basis of the above scheme, maxwell differential equations of the stray current are shown in formulas (4) and (5) in a basic form, and auxiliary equations are shown in formulas (6) and (7):
Figure BDA0003024633500000071
Figure BDA0003024633500000072
Figure BDA0003024633500000073
Figure BDA0003024633500000074
wherein E is the electric field intensity (V/m); j is the current density (A/m)2)；ρvIs the bulk charge density (C/m)3) (ii) a σ is the conductivity (S/m); u is a scalar potential (V);
based on the expression, the field quantity U to be solved is used to describe two types of equations of the current field, wherein the two types of equations are Laplace equations without current sources, as shown in formula (8), and Poisson equations with current sources, as shown in formula (9):
Figure BDA0003024633500000081
Figure BDA0003024633500000082
and establishing a fine earth resistivity model according to the earth electrical property, the construction data and the data thereof, and further calculating the earth potential of the peripheral substation of the subway. It should be noted that the position of the subway train is constantly changing during operation, so if the subway runs a plurality of trains at turning, intersection, parallel and other positions simultaneously, the ground potential generated by stray current generated by the trains can be used for researching the ground potential dynamically distributed by the trains by using the superposition law. Under the actual operation condition, a plurality of trains which run simultaneously are possible, and the change of the potential and the time of the transformer substation is required to be considered.
When the subway normally operates, if stray current flows into the ground, the stray current flowing into the ground is regarded as a driving current source, and the solving problem of potential distribution can be converted into mathematical description of a current field. Specifically, a field equation is deduced by taking a Maxwell equation set as a theoretical basis, and a ground potential distribution rule is expressed by solving the field equation near a rail. The field domain equation is firstly derived from the Maxwell equation system, the basic form of the differential equation of the current field can be obtained as shown in the formulas (4) and (5), the auxiliary equation is shown in the formulas (6) and (7), and the field quantity U to be solved is used for describing the current field, so that the differential equation has two forms as shown in the formulas (8) and (9). Since the electric field equation is unique, a unique solution can be found by determining the electric field whenever the field boundary conditions are determined. Therefore, the boundary condition of the electric field equation near the subway track is found, the boundary condition is that voltage and current at infinity are all 0, and the potential change distribution near the subway track can be obtained by solving the equation by adopting a finite element method.
Further, the specific steps of step 3 are:
analyzing the influence factors of the bias current in the power grid when the subway normally operates;
and considering the influence of the influence factor of the bias current, simplifying data and parameters such as a power grid structure, wire resistance, transformer wiring, winding resistance and the like according to a GIC-Benchmark method to obtain a simplified bias current equivalent circuit of the transformer substation and the power supply line.
Further, calculating the bias current by adopting a KVL method;
the KVL equation system for calculating the bias current is:
Figure BDA0003024633500000091
wherein n is the number of nodes, I0For the distribution of the stray current into the ground, RiiIs point i self-admittance, i is 1,2, …, n, RijIs the mutual admittance of point i and point j, j is 1,2, …, n, uiAnd IiThe potential and current of the grounding point i.
The change of the ground potential can generate a potential difference between two grounds of the transformer, and further generate a magnetic bias current in a power grid. And establishing a bias current model of the power grid based on the GIC-Benchmark and the topological structure of the power grid.
When a subway normally runs, the actual magnetic bias current in a power grid is complex, the factors influencing the magnetic bias current of the power grid are many, the influence of the factors is considered, the data and parameters of the power grid are simplified according to GIC-Benchmark, and a simplified equivalent circuit of the magnetic bias current of a transformer substation and a power supply line is shown in fig. 3. Wherein, Ui(i 1, 2., n) is the potential equivalent to the neutral point of the transformer acting on two substations, Ri(i ═ 1,2, …, n) is the line equivalent resistance. The bias current of the power grid can be calculated by adopting a node voltage method (formula 10).
The following describes an application of the above calculation method, taking a subway in a certain city as an example.
A typical subway map of a city is shown in fig. 4, and data information for establishing earth and power grid models is shown in table 1. According to data and data in the figure 4 and the table 1, the earth potential and power grid bias current algorithm is adopted to establish an earth potential model and a power grid bias current model of a nearby subway region, and the bias current of the urban 220kV transformer neutral point is calculated by MATLAB programming in consideration of the influence of factors such as train running speed, train quantity and the like. In order to improve the calculation precision, the total length of the simulation line is 2000 calculation infinitesimals, wherein the calculation infinitesimals are 1m during simulation calculation, and the total length of the simulation line is 2000 m. The relevant simulation parameter settings are as follows.
TABLE 1 simulation resistance parameter (per 1m infinitesimal value)
Figure BDA0003024633500000101
The simulation shows that the stray current between subway stations along the subway line in fig. 4 is shown in fig. 5, and the ground potential change along the subway line is shown in fig. 6. In the calculation, the equivalent earth resistance data is 200 Ω/m, the train is supposed to be sent from the starting station every five minutes according to the running schedule, the train running time between the stations is 2min, the running mode is that the first 40s is acceleration time, the last 40s is deceleration time, and the middle running is uniform motion.
According to the calculated ground potential along the subway and the established bias current model of the urban power grid, the ground potential of each substation of the power grid and the potential difference between the grounding points of the two transformer substations of the power grid can be calculated, and then the magnitude of the direct current bias current of the neutral points of the two transformer substations, which changes along with the ground potential, can be calculated. The results obtained are shown in fig. 7 and 8.
The invention adopts a three-layer physical model of subway-earth-power grid, completes the theoretical calculation of the influence of the leakage stray current of the subway system on the DC magnetic bias current of the urban network transformer, and obtains the following main research conclusion:
1) in two substations, the maximum value of the magnetic bias current of one substation transformer is 12.8A, the average value within one minute also reaches 7.58A, and the maximum value of the reverse magnetic bias current is 5.68A, and appears periodically. When the operating rule of the transformer exceeds 3A, the transformer needs to be treated, and measures for treating the transformer magnetic bias caused by the subway are taken.
2) In a substation within the influence range along the same subway, if the number of feeders inserted into the substation and the number of defense lines connected into the substation are different, the direct-current magnetic bias current of the neutral point of the transformer of the substation is also different, and the magnitude and the variation trend of the magnetic bias current of the power grid are related to the operation mode of the subway and the topological structure of the power grid.
3) Because the subway train runs at a high speed, the trains on the same subway line are many times, and the ground potential can be rapidly changed in a large area, the bias current of the transformer can change the direction within one minute for many times.
Those not described in detail in this specification are within the skill of the art.

Claims (7)

1. A method for calculating bias current of a transformer based on a subway near-zone earth and power grid model is characterized by comprising the following steps:
step 1: establishing a resistance network model, and calculating stray current leaked from the steel rail and flowing into the ground during the operation of the subway through the resistance network model;
step 2: establishing a three-dimensional resistivity model of the earth according to the earth electrical property and the construction data thereof, and calculating the ground potential of the subway near-region transformer substation by using the three-dimensional resistivity model of the earth;
and step 3: analyzing influence factors of power grid bias current, and simplifying a power grid structure, a lead resistor, transformer wiring and winding resistance by using a GIC-Benchmark method to obtain a simplified transformer substation and power supply circuit bias current equivalent circuit;
and 4, step 4: and (3) establishing a power grid magnetic bias current model based on the GIC-Benchmark method and the equivalent circuit obtained in the step (3), and calculating the direct current magnetic bias current of each transformer substation neutral point of the power grid.
2. The method for calculating the bias current of the transformer based on the near-zone earth and power grid model of the subway as claimed in claim 1, wherein in step 1, the flow path of the stray current is that the stray current leaks outwards from the rail at the train wheel, enters the earth through the rail track bed structure and the drainage network, and flows back to the substation from the earth.
3. The method for calculating the bias current of the transformer based on the subway near-zone earth and power grid model according to claim 2, wherein the specific steps in the step 1 are as follows:
firstly, considering the condition that a pipeline and a track are distributed in parallel, simplifying the track, a drainage network and the ground into laminated resistors, establishing a resistor network model, and then calculating to obtain stray current when a train runs to a certain position according to resistance data and the resistor network model;
the train is set to travel from location 1 to location 2, resulting in stray current flowing from rail leakage into the ground during operation of the train.
4. The method for calculating the bias current of the transformer based on the subway near-zone earth and power grid model as claimed in claim 3, wherein KCL and KVL equations of the resistance network model are respectively:
Figure FDA0003024633490000021
Figure FDA0003024633490000022
in the formula:
Figure FDA0003024633490000023
representing the current on the track, RGRepresenting the longitudinal resistance of the rail, RPIn order to drain the longitudinal resistance of the wire,
Figure FDA0003024633490000024
is the current of the drainage network, g1Is the transition conductance of the rail and the drainage network, g2Is the transition conductance of the drainage network to earth, u1(x) Representing the voltage on the transition conductance of the track and the drainage network, u2(x) Representing the voltage on the transition conductance of the drainage network to earth;
assuming that the total stray current generated when the train runs to a distance of x meters from the transformer substation is IscOf stray current IscThe calculation formula of (2) is as follows:
Figure FDA0003024633490000025
Iscnamely the stray current when the train runs on the whole line,
Figure FDA0003024633490000026
which is representative of the current on the track,
Figure FDA0003024633490000027
is the current of the drainage network, I is the current through the train, Isc1、isc2Representing the stray current of each micro-element.
5. The method for calculating the bias current of the transformer based on the subway near-zone earth and power grid model according to claim 4, wherein the specific steps in the step 2 are as follows:
supposing that the subway normally operates, stray current flows into the ground, and the stray current entering the ground is taken as a driving current source of the bias current of the transformer in the near area of the subway;
and deducing and solving field equations near the rails based on the Maxwell equation set, and expressing the earth potential distribution rule by using the field equations.
6. The method for calculating the bias current of the transformer based on the near-zone earth and power grid model of the subway as claimed in claim 5, wherein maxwell differential equations of the stray currents are shown in the basic forms as formulas (4) and (5), and auxiliary equations thereof are shown in the formulas (6) and (7):
Figure FDA0003024633490000028
Figure FDA0003024633490000029
Figure FDA00030246334900000210
Figure FDA0003024633490000031
wherein the content of the first and second substances,
Figure FDA0003024633490000032
representing del operator, → is the vector sign, and E is the electric field strength; j is the current density; rhovIs the bulk charge density; σ is the conductivity; u is a scalar potential and t is time;
based on the expression, the field quantity U to be solved is used to describe two types of equations of the current field, wherein the two types of equations are Laplace equations without current sources, as shown in formula (8), and Poisson equations with current sources, as shown in formula (9):
Figure FDA0003024633490000033
Figure FDA0003024633490000034
7. the method for calculating the bias current of the transformer based on the near-zone earth and power grid model of the subway as claimed in claim 6, wherein the bias current is calculated by adopting a KVL method;
the KVL equation system for calculating the bias current is:
Figure FDA0003024633490000035
wherein n is the number of nodes, I0For the distribution of the stray current into the ground, RiiIs point i self-admittance, i is 1,2, …, n, RijIs the mutual admittance of point i and point j, j is 1,2, …, n, uiAnd IiIs the potential and current of the earth point i, R0iIs the equivalent ground resistance of the substation.
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Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN113836718A (en) * 2021-09-23 2021-12-24 中铁第四勘察设计院集团有限公司 Direct-current magnetic bias calculation method for transformer of high-speed magnetic levitation main substation
CN114325044A (en) * 2021-12-21 2022-04-12 国网上海市电力公司 Method and system for judging relevance between direct current bias magnet of transformer substation and direct current fluctuation source of rail transit
CN115600458A (en) * 2022-10-11 2023-01-13 苏州大学（Cn） Stray current dynamic distribution calculation method considering three-dimensional ground system
CN116680850A (en) * 2023-07-28 2023-09-01 西华大学 Modeling calculation method and system for network subway stray current considering reflow equipment
CN117892211A (en) * 2024-03-11 2024-04-16 国网上海市电力公司 SVM-based subway and power grid electromagnetic coupling fault identification method

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN109256771A (en) * 2018-10-16 2019-01-22 国网湖南省电力有限公司 Metro stray current and its caused transformer neutral point DC current calculation method
CN110427703A (en) * 2019-08-03 2019-11-08 国网山西省电力公司电力科学研究院 A kind of stray electrical current emulation modelling method based under the conditions of multi-train movement
CN111338233A (en) * 2020-03-03 2020-06-26 西南交通大学 Simulation modeling method for subway stray current distribution in urban power grid

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN109256771A (en) * 2018-10-16 2019-01-22 国网湖南省电力有限公司 Metro stray current and its caused transformer neutral point DC current calculation method
CN110427703A (en) * 2019-08-03 2019-11-08 国网山西省电力公司电力科学研究院 A kind of stray electrical current emulation modelling method based under the conditions of multi-train movement
CN111338233A (en) * 2020-03-03 2020-06-26 西南交通大学 Simulation modeling method for subway stray current distribution in urban power grid

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
伍国兴等: "城轨杂散电流在电网系统中的分布特性仿真分析", 《南方电网技术》 *

Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN113836718A (en) * 2021-09-23 2021-12-24 中铁第四勘察设计院集团有限公司 Direct-current magnetic bias calculation method for transformer of high-speed magnetic levitation main substation
CN113836718B (en) * 2021-09-23 2023-12-29 中铁第四勘察设计院集团有限公司 Direct-current magnetic bias calculation method for high-speed magnetic levitation main transformer substation
CN114325044A (en) * 2021-12-21 2022-04-12 国网上海市电力公司 Method and system for judging relevance between direct current bias magnet of transformer substation and direct current fluctuation source of rail transit
CN114325044B (en) * 2021-12-21 2023-08-01 国网上海市电力公司 Method and system for judging relevance of direct-current magnetic bias of transformer substation and direct-current fluctuation source of rail transit
CN115600458A (en) * 2022-10-11 2023-01-13 苏州大学（Cn） Stray current dynamic distribution calculation method considering three-dimensional ground system
CN115600458B (en) * 2022-10-11 2024-05-10 苏州大学 Stray current dynamic distribution calculation method considering three-dimensional ground system
CN116680850A (en) * 2023-07-28 2023-09-01 西华大学 Modeling calculation method and system for network subway stray current considering reflow equipment
CN116680850B (en) * 2023-07-28 2023-10-10 西华大学 Modeling calculation method and system for network subway stray current considering reflow equipment
CN117892211A (en) * 2024-03-11 2024-04-16 国网上海市电力公司 SVM-based subway and power grid electromagnetic coupling fault identification method

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