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CN118013904B - Method and device for calculating DC frequency distribution of neutral point of transformer - Google Patents

Method and device for calculating DC frequency distribution of neutral point of transformer Download PDF

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Publication number
CN118013904B
CN118013904B CN202410162461.2A CN202410162461A CN118013904B CN 118013904 B CN118013904 B CN 118013904B CN 202410162461 A CN202410162461 A CN 202410162461A CN 118013904 B CN118013904 B CN 118013904B
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subway
model
traction current
resistance
calculating
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CN118013904A (en
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王爱民
李宇
王军
李贤胤
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Xihua University
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Xihua University
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    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—ELECTRIC POWER NETWORKS; CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J3/00—Circuit arrangements for AC mains or AC distribution networks
    • G—PHYSICS
    • G06—COMPUTING OR CALCULATING; COUNTING
    • G06F—ELECTRIC DIGITAL DATA PROCESSING
    • G06F30/00—Computer-aided design [CAD]
    • G06F30/30—Circuit design
    • G06F30/32—Circuit design at the digital level
    • G06F30/33—Design verification, e.g. functional simulation or model checking
    • G06F30/3323—Design verification, e.g. functional simulation or model checking using formal methods, e.g. equivalence checking or property checking
    • G—PHYSICS
    • G06—COMPUTING OR CALCULATING; COUNTING
    • G06F—ELECTRIC DIGITAL DATA PROCESSING
    • G06F2113/00—Details relating to the application field
    • G06F2113/04—Power grid distribution networks
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—ELECTRIC POWER NETWORKS; CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J2103/00—Details of circuit arrangements for mains or AC distribution networks
    • H02J2103/30—Simulating, planning, modelling, reliability check or computer assisted design [CAD] of electric power networks

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  • General Engineering & Computer Science (AREA)
  • General Physics & Mathematics (AREA)
  • Power Engineering (AREA)
  • Supply And Distribution Of Alternating Current (AREA)

Abstract

本申请提供变压器中性点直流频率分布计算方法及装置，其中所述方法包括：通过地铁列车的列车速度对地铁线路进行分段，计算得到的地铁分段的等效电阻，进行地铁电阻等效模型的构建，结合城市电网构建电网‑地铁等效模型；根据地铁列车牵引电流信息与地铁分段，构建牵引电流时域分布模型，并进一步构建牵引电流频域分布模型；根据牵引电流频域分布模型与电网‑地铁电阻等效模型，构建变压器中性点直流频率分布计算模型，实现对变压器中性点电流频率分布的计算，直观展示地铁杂散电流引起的中性点直流电关于时间的变化特性，保障地铁杂散电流影响变压器直流偏磁及继电保护研究的准确性。

The present application provides a method and device for calculating the neutral point DC frequency distribution of a transformer, wherein the method comprises: segmenting a subway line according to the train speed of a subway train, calculating the equivalent resistance of the subway segment, constructing a subway resistance equivalent model, and constructing a power grid-subway equivalent model in combination with the urban power grid; constructing a traction current time domain distribution model according to the subway train traction current information and the subway segmentation, and further constructing a traction current frequency domain distribution model; constructing a transformer neutral point DC frequency distribution calculation model according to the traction current frequency domain distribution model and the power grid-subway resistance equivalent model, realizing the calculation of the transformer neutral point current frequency distribution, intuitively displaying the time variation characteristics of the neutral point DC caused by the subway stray current, and ensuring the accuracy of the research on the influence of the subway stray current on the transformer DC bias magnetization and relay protection.

Description

Method and device for calculating DC frequency distribution of neutral point of transformer
Technical Field
The application relates to the technical field of modeling of power systems, in particular to a method for calculating DC frequency distribution of a neutral point of a transformer. The application also relates to a transformer neutral point direct current frequency distribution calculating device, a calculating equipment and a computer readable storage medium.
Background
The subway adopts direct current power supply, and the steel rail flows back, so that the steel rail cannot be completely insulated from the ground, and the backflow current in the steel rail leaks the steel rail to form stray current. The leaked subway stray current enters the urban power grid to cause the DC increase of the main transformer neutral point, and the DC magnetic bias phenomenon occurs. In the urban power grid transformer substation with high coverage rate of partial subway network, high-level neutral point direct current with the amplitude of 20A to 80A has been measured, and serious transformer direct current magnetic bias phenomenon is caused, so that the vibration noise of the transformer is aggravated, the harmonic content is increased, the operation safety of transformer equipment is threatened, and the differential protection of the transformer is refused or is wrongly operated.
At present, a great deal of deep theoretical research and engineering analysis are carried out on the influence of constant direct current and fixed frequency alternating current on the direct current magnetic bias of a transformer and relay protection of the transformer, but from the field test data of the neutral point direct current of the transformer of an urban power grid, the neutral point direct current caused by subway stray current is not ideal direct current, but changes with time, positive and negative alternating characteristics are presented, and the frequency distribution characteristics of the neutral point direct current are not clear. However, in the prior art, the influence of the transformer neutral point direct current caused by the subway stray current on the safety of the transformer and the system is analyzed, and the frequency distribution characteristics of the transformer neutral point direct current caused by the subway stray current are often ignored.
Disclosure of Invention
In view of this, the embodiment of the application provides a method for calculating the dc frequency distribution of the neutral point of a transformer, so as to solve the technical defects existing in the prior art. The embodiment of the application also provides a transformer neutral point direct current frequency distribution calculating device, a calculating device and a computer readable storage medium.
According to a first aspect of an embodiment of the present application, there is provided a method for calculating a dc frequency distribution of a neutral point of a transformer, including:
calculating the train speed of a subway train based on the acquired subway network information, and segmenting a subway line through the train speed to obtain subway segments;
Calculating the equivalent resistance of the subway segment according to the subway network information, and constructing a subway resistance network equivalent model based on a calculation result;
acquiring urban power grid information, and constructing a power grid-subway resistance equivalent model according to the urban power grid information and the subway resistance network equivalent model;
Constructing a traction current time domain distribution model according to the subway train traction current information and the subway segments contained in the subway network information, and constructing a traction current frequency domain distribution model according to the traction current time domain distribution model;
and constructing a transformer neutral point direct current frequency distribution calculation model through the traction current frequency domain distribution model and the power grid-subway resistance equivalent model, and calculating transformer neutral point current frequency distribution.
Optionally, calculating the train speed of the subway train based on the obtained subway network information, and segmenting the subway line by using the train speed to obtain the subway segment includes:
Calculating the train speed through subway line mileage and train operation time length contained in the subway network information;
Calculating the subway segment length according to the preset acquisition duration and the train speed;
And dividing the subway line based on the length of the subway section to obtain the subway section.
Optionally, the calculating the equivalent resistance of the subway segment according to the subway network information, and constructing the subway resistance network equivalent model based on the calculation result includes:
Calculating the equivalent resistance of the subway section according to the equivalent resistance information contained in the subway network information;
and constructing the subway resistance network equivalent model according to the mapping relation between the subway segments and the subway line.
Optionally, the collecting urban power grid information, and constructing the power grid-subway resistance equivalent model according to the urban power grid information and the subway resistance network equivalent model includes:
collecting urban power grid information;
constructing a direct current resistance equivalent model of the urban power grid according to the urban power grid information;
Inquiring a butt joint mode of the subway resistance network equivalent model and the city power grid direct current resistance equivalent model according to the city power grid information, and constructing a power grid-subway resistance equivalent model based on an inquiry result.
Optionally, the constructing a traction current time domain distribution model according to the subway train traction current information and the subway segment contained in the subway network information includes:
Inquiring the subway network information, and determining the traction current information containing the running position of the subway train and the corresponding traction current;
calculating departure interval time and stop time of the subway train based on the subway network information;
and constructing a traction current time domain distribution model according to the subway section, the running position, traction current corresponding to the running position, the departure interval duration and the stop duration.
Optionally, calculating the departure interval duration and the stop duration of the subway train based on the subway network information includes:
inquiring a subway line train schedule contained in the subway network information;
according to the query result, calculating the average value of subway train departure time in the preset time length as the departure interval time length, and the average value of arrival stop time as the stop time length.
Optionally, the constructing a transformer neutral point direct current frequency distribution calculation model through the traction current frequency domain distribution model and the grid-subway resistance equivalent model includes:
calculating traction current frequency domain parameters corresponding to each subway segment through a traction current frequency domain model;
and constructing the transformer neutral point direct current frequency distribution calculation model by combining the traction current frequency domain parameters and the power grid-subway resistance equivalent model.
Optionally, the constructing a traction current frequency domain distribution model according to the traction current time domain distribution model includes:
And carrying out Fourier transform on the traction current time domain distribution model to obtain the traction current frequency domain distribution model.
Optionally, the calculating the transformer neutral point current frequency distribution includes:
calculating the output of the DC frequency distribution calculation model of the neutral point of the transformer under the condition of different frequencies through kirchhoff's law, and obtaining the voltages at two ends of a branch where the neutral point of the transformer is located;
And calculating the voltages at two ends of the branch where the neutral point of the transformer is located according to ohm law, and obtaining the current distribution of the neutral point of the transformer with different frequencies.
According to a second aspect of the embodiment of the present application, there is provided a transformer neutral point dc frequency distribution calculating apparatus, including:
the system comprises a segmentation model, a control module and a control module, wherein the segmentation model is configured to calculate the train speed of a subway train based on acquired subway network information and segment a subway line through the train speed to obtain subway segments;
The model construction module is configured to calculate the equivalent resistance of the subway section according to the subway network information and construct a subway resistance network equivalent model based on a calculation result;
The model link module is configured to collect urban power grid information and construct a power grid-subway resistance equivalent model according to the urban power grid information and the subway resistance network equivalent model;
The traction current processing module is configured to construct a traction current time domain distribution model according to the subway train traction current information and the subway segments contained in the subway network information, and construct a traction current frequency domain distribution model according to the traction current time domain distribution model;
The calculation module is configured to construct a transformer neutral point direct current frequency distribution calculation model through the traction current frequency domain distribution model and the power grid-subway resistance equivalent model, and calculate transformer neutral point current frequency distribution.
According to a third aspect of embodiments of the present application, there is provided a computing device comprising:
A memory and a processor;
The memory is used for storing computer executable instructions, and the processor realizes the steps of the transformer neutral point DC frequency distribution calculation method when executing the computer executable instructions.
According to a fourth aspect of embodiments of the present application, there is provided a computer readable storage medium storing computer executable instructions which, when executed by a processor, implement the steps of the transformer neutral dc frequency distribution calculation method.
According to a fifth aspect of the embodiments of the present application, there is provided a chip storing a computer program which, when executed by the chip, implements the steps of the transformer neutral dc frequency distribution calculation method.
According to the transformer neutral point direct current frequency distribution calculation method, the train speed of a subway train is calculated based on the acquired subway network information, and a subway line is segmented through the train speed to obtain subway segments; calculating the equivalent resistance of the subway segment according to the subway network information, and constructing a subway resistance network equivalent model based on a calculation result; acquiring urban power grid information, and constructing a power grid-subway resistance equivalent model according to the urban power grid information and the subway resistance network equivalent model; constructing a traction current time domain distribution model according to the subway train traction current information and the subway segments contained in the subway network information, and constructing a traction current frequency domain distribution model according to the traction current time domain distribution model; and constructing a transformer neutral point direct current frequency distribution calculation model through the traction current frequency domain distribution model and the power grid-subway resistance equivalent model, calculating transformer neutral point current frequency distribution, intuitively displaying the time-dependent change characteristic of the neutral point direct current caused by subway stray current, and guaranteeing the accuracy of the influence of the subway stray current on the transformer direct current magnetic bias and relay protection research.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for the description of the embodiments will be briefly described below, and it is apparent that the drawings in the following description are only some embodiments of the present application, and other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.
Fig. 1 is a flowchart of a method for calculating a dc frequency distribution of a neutral point of a transformer according to an embodiment of the present application;
fig. 2 is a schematic diagram of a method for calculating dc frequency distribution of a neutral point of a transformer according to an embodiment of the present application;
fig. 3 is a process flow chart of a method for calculating dc frequency distribution of a neutral point of a transformer applied to stray current of a subway according to an embodiment of the present application;
Fig. 4 is a schematic diagram of a traction current time domain distribution of a calculation method of a transformer neutral point dc frequency distribution according to an embodiment of the present application;
Fig. 5 is a schematic diagram of a calculation model of a dc frequency distribution of a neutral point of a transformer according to an embodiment of the present application;
Fig. 6 is a schematic structural diagram of a transformer neutral dc frequency distribution calculating device according to an embodiment of the present application;
FIG. 7 is a block diagram of a computing device according to one embodiment of the application.
Detailed Description
In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present application. The present application may be embodied in many other forms than those herein described, and those skilled in the art will readily appreciate that the present application may be similarly embodied without departing from the spirit or essential characteristics thereof, and therefore the present application is not limited to the specific embodiments disclosed below.
The terminology used in the one or more embodiments of the application is for the purpose of describing particular embodiments only and is not intended to be limiting of the one or more embodiments of the application. As used in one or more embodiments of the application and the appended claims, the singular forms "a," "an," and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It should also be understood that the term "and/or" as used in one or more embodiments of the present application refers to and encompasses any or all possible combinations of one or more of the associated listed items.
It should be understood that, although the terms first, second, etc. may be used in one or more embodiments of the application to describe various information, these information should not be limited by these terms. These terms are only used to distinguish one type of information from another. For example, a first may also be referred to as a second, and similarly, a second may also be referred to as a first, without departing from the scope of one or more embodiments of the application.
First, terms related to one or more embodiments of the present invention will be explained.
Stray current: the current flowing outside the designed or prescribed loop is also referred to as "current sinking". It flows in the soil and is independent of the protected pipe system.
Neutral point: the common point of star connection in three-phase or multi-phase AC system is the zero point, which is grounded or not grounded according to the operation requirement.
The application provides a method for calculating the DC frequency distribution of a neutral point of a transformer. The present application also relates to a transformer neutral point dc frequency distribution calculating apparatus, a calculating device, and a computer-readable storage medium, which are described in detail in the following embodiments.
Fig. 1 shows a flowchart of a method for calculating a dc frequency distribution of a neutral point of a transformer according to an embodiment of the present application, which specifically includes the following steps:
s102: calculating the train speed of a subway train based on the acquired subway network information, and segmenting a subway line through the train speed to obtain subway segments;
s104: calculating the equivalent resistance of the subway segment according to the subway network information, and constructing a subway resistance network equivalent model based on a calculation result;
S106: acquiring urban power grid information, and constructing a power grid-subway resistance equivalent model according to the urban power grid information and the subway resistance network equivalent model;
s108: constructing a traction current time domain distribution model according to the subway train traction current information and the subway segments contained in the subway network information, and constructing a traction current frequency domain distribution model according to the traction current time domain distribution model;
S110: and constructing a transformer neutral point direct current frequency distribution calculation model through the traction current frequency domain distribution model and the power grid-subway resistance equivalent model, and calculating transformer neutral point current frequency distribution.
The subway network information is all information related to the subway, such as position information, circuit information, structure information, train operation information and the like, specifically, such as urban subway network topology information, metal structure resistance, transition resistance between metals, transition resistance between metal and ground, resistance of a steel rail limiting device, unit resistance value of a longitudinal metal structure such as a neighboring station mileage, a steel rail, a drainage network, a through ground wire and the like, a subway train operation chart and a timetable, a subway train operation position, related traction current and the like, and the subway network information only needs to complete calculation of related parameters and execution of related steps, and the number and types of specific parameters contained in the subway network information are determined by actual use scenes, so that the embodiment is not limited.
Similarly, the urban power grid information is all information related to the urban power grid, such as transformer substation geographic information, transformer substation grounding resistance, direct current resistance parameters of a transformer, a power transmission line, a cable core and an armor (sheath), urban power grid topology, a transformer neutral point grounding mode, a cable armor (sheath) grounding mode and the like. It should be noted that, the urban power grid information only needs to complete the calculation of the related parameters and the execution of the related steps, and the number and types of the specific parameters contained in the urban power grid information are determined by the actual use scenario, which is not limited in this embodiment. The subway train traction current information is related information comprising the running position of the subway train and the corresponding traction current.
Based on the subway network information, the speed of a subway train is calculated according to the subway network information, and the longitudinal metal structure along the subway line is segmented; then calculating the corresponding equivalent resistance of the structure contained in each longitudinal metal structure section through subway network information, and establishing a subway resistance network equivalent model; acquiring urban power grid information, and constructing a power grid-subway resistance equivalent model according to the urban power grid information and the subway resistance network equivalent model; according to subway train traction current information, a traction current time domain distribution model is established, the corresponding relation between the train traction current and time is defined, and the representation form of the train traction current on a frequency domain is further displayed through the traction current frequency domain distribution model; and combining the traction current frequency domain distribution model with a power grid-subway resistance equivalent model to realize calculation of the current frequency distribution of the neutral point of the transformer. By segmenting a subway line and combining the relationship between the position of a subway train and traction current, a discrete traction current time domain distribution model is established, the time-varying characteristic of neutral point direct current caused by subway stray current is intuitively displayed, the time domain model is subsequently converted into a frequency domain model, the frequency distribution characteristic of transformer neutral point direct current caused by subway stray current is clarified, and the accuracy of transformer direct current magnetic bias and relay protection research is ensured.
Further, in the process of segmenting the subway line, in this embodiment, the specific implementation manner is as follows:
Calculating the train speed through subway line mileage and train operation time length contained in the subway network information; calculating the subway segment length according to the preset acquisition duration and the train speed; and dividing the subway line based on the length of the subway section to obtain the subway section.
The subway line mileage is understood as topological network topology information of the subway line, length parameters of the subway line and the like, and is used for representing presentation form information of the subway line in space.
Based on this, in the actual use scenario, the running speeds of different subway lines, up-down trains, train running speeds between different stations and train running speeds at different moments are not always consistent, in order to ensure the splitting of the subway lines, the running speeds of the subway trains in the sampling time need to be calculated on average, specifically, the average value can be calculated by subtracting the time spent in stopping at the station from the total time spent between the initial station and the terminal station of all the subway trains in each line and combining the total mileage of the running trains. As shown in the schematic diagram of the method for calculating the dc frequency distribution of the neutral point of the transformer provided in fig. 2, the average running speed of the train is calculated according to the running chart and the schedule of the train, and it should be noted that the data such as the schedule may also be used to determine the departure interval time and the stop time of the train, and may be calculated preferentially, or may be calculated in the subsequent steps, and the specific calculation sequence is determined by the actual use scenario, which is not limited in this embodiment.
After the train speed is obtained, the minimum time unit of the traction current time domain distribution model which needs to be generated subsequently is the preset acquisition time length, the acquisition time length is multiplied by the train speed, the subway section length can be obtained, and the subway line is divided according to the subway section length, so that the subway section is obtained. And the subsequent calculation of the transformer neutral point current frequency distribution by combining a discrete form traction current time domain distribution model is facilitated.
In the process of dividing the subway line between two adjacent stations, the station sections which cannot be divided into the whole number are divided by rounding, and the number of the sections and the section length between the two adjacent stations are recorded.
Further, in the process of constructing the subway resistance network equivalent model, in this embodiment, the specific implementation manner is as follows:
Calculating the equivalent resistance of the subway section according to the equivalent resistance information contained in the subway network information; and constructing the subway resistance network equivalent model according to the mapping relation between the subway segments and the subway line.
The resistance equivalent information is information such as a metal structure resistance, a transition resistance between metals, a metal-to-ground transition resistance, a rail limiting device resistance, an adjacent station mileage, a unit resistance value of a longitudinal metal structure such as a rail, a drainage network, a through ground wire and the like, and the specific information selection is determined by an actual use scene, and the embodiment is not limited.
Based on the equivalent resistance calculation, the longitudinal metal structure in the subway section is calculated according to the equivalent resistance information contained in the subway network information, and then the subway section is based on the reduced subway line topological structure according to the mapping relation between each subway section and the subway line, so as to establish a subway resistance network equivalent model formed by the equivalent resistances of the subway sections in a series-parallel connection mode. The method is favorable for being combined with a discrete form traction current time domain distribution model to calculate the transformer neutral point current frequency distribution.
Further, in the process of constructing the electric network-subway resistance equivalent model, in this embodiment, the specific implementation manner is as follows:
collecting urban power grid information; constructing a direct current resistance equivalent model of the urban power grid according to the urban power grid information; inquiring a butt joint mode of the subway resistance network equivalent model and the city power grid direct current resistance equivalent model according to the city power grid information, and constructing a power grid-subway resistance equivalent model based on an inquiry result.
According to the geographic information of a transformer substation in the urban power grid, the grounding resistance of the transformer substation, the direct current resistance parameters of a transformer, a power transmission line, cable cores and armor (sheath), and the like, which are contained in the urban power grid information, an urban power grid direct current resistance equivalent model is established according to the information such as the urban power grid topology, the grounding mode of a neutral point of the transformer, the grounding mode of a cable armor (sheath), and the like, and a power grid-subway resistance equivalent model is established according to the grounding mode of a subway main station and an urban power grid transformer substation cable, the resistance value of the cable armor unit length, and the subway main station in-out line cable armor equivalent resistance is utilized to connect the subway resistance network equivalent model and the urban power grid direct current resistance equivalent model.
Based on this, as shown in the schematic diagram of the transformer neutral point dc frequency distribution calculation method provided in fig. 2, through step 2 and step 3, a subway stray current resistance network equivalent model, that is, a subway resistance equivalent model is established, and a resistance network model unified by a subway and a city power grid, that is, a power grid-subway resistance equivalent model is established by combining relevant parameters of the city power grid.
Further, because the subway train is stopped by standing in the actual running process, and the subway train does not have traction current under the condition, the constructed traction current time domain distribution model is in a discrete form, and in the embodiment, the specific implementation mode is as follows:
Inquiring the subway network information, and determining the traction current information containing the running position of the subway train and the corresponding traction current; calculating departure interval time and stop time of the subway train based on the subway network information; and constructing a traction current time domain distribution model according to the subway section, the running position, traction current corresponding to the running position, the departure interval duration and the stop duration.
The subway network information comprises traction current information, and the traction current information comprises subway train running positions and corresponding traction currents.
Based on this, as shown in the schematic diagram of the transformer neutral point dc frequency distribution calculation method provided in fig. 2, since the process of subway line segmentation is related to the train speed and the sampling duration, and the train position and the train segmentation have a corresponding relationship, the corresponding relationship between the train position and the sampling duration can be established, and further, the traction current time domain distribution model related to the three elements of the train position, the time and the traction current can be established by combining the traction current of the running position, the train departure interval duration and the stop duration.
The established traction current time domain distribution model can be divided into traction current on station nodes and traction current not on stations, traction current of an ascending train and traction current of a descending train due to limitation of an actual subway operation mode.
Further, the process of calculating the departure interval duration and the stop duration is implemented as follows in this embodiment:
Inquiring a subway line train schedule contained in the subway network information; according to the query result, calculating the average value of subway train departure time in the preset time length as the departure interval time length, and the average value of arrival stop time as the stop time length.
The preset time length is determined by the actual use situation, but the embodiment is not limited, so that the preset time length is not too short to ensure the accuracy of sampling. As shown in the schematic diagram of the method for calculating the dc frequency distribution of the neutral point of the transformer in fig. 2, it should be noted that the calculation of the departure interval and the stop time is set in step 1, but in this embodiment, before the drawing current time domain distribution model is set up, the two execution orders do not affect the execution effect of the scheme, and the specific execution order is not limited in this embodiment.
It should be noted that, for the calculation of the departure interval time and the stop time of the subway train, the calculation may be performed by manual sampling, that is, the average value of the departure time and the average value of the arrival stop time of the subway train obtained by manual timing may be calculated, and the specific selection manner is determined by the actual use scenario, which is not limited in this embodiment.
Further, in the process of constructing the transformer neutral point dc frequency distribution calculation model, in this embodiment, the specific implementation manner is as follows:
calculating traction current frequency domain parameters corresponding to each subway segment through a traction current frequency domain model; and constructing the transformer neutral point direct current frequency distribution calculation model by combining the traction current frequency domain parameters and the power grid-subway resistance equivalent model.
The traction current frequency domain parameters are used for representing traction currents of the traction currents on the corresponding subway sections under different frequency conditions.
Based on this, the traction current when the frequency of each subway segment takes different values is calculated through the traction current frequency domain model, and it is to be noted that in an actual use scenario, the creation of the time domain model and the frequency domain model related to the traction current of the subway train often needs to be created separately for the up-down trains, and when the frequency domain parameters of the traction current corresponding to a certain subway segment are calculated, the frequency domain models of the up-down subway trains on the subway segment need to be added.
Further, in the process of converting the traction current time domain distribution model into the traction current frequency domain distribution model, the specific implementation manner is as follows:
And carrying out Fourier transform on the traction current time domain distribution model to obtain the traction current frequency domain distribution model.
Further, in the process of calculating the frequency distribution of the neutral point current of the transformer, in this embodiment, the specific implementation manner is as follows:
Calculating the output of the DC frequency distribution calculation model of the neutral point of the transformer under the condition of different frequencies through kirchhoff's law, and obtaining the voltages at two ends of a branch where the neutral point of the transformer is located; and calculating the voltages at two ends of the branch where the neutral point of the transformer is located according to ohm law, and obtaining the current distribution of the neutral point of the transformer with different frequencies.
In step 4 and step 5, a time domain model is converted into a frequency domain model through fourier transform, different frequency values are given to each subway segment in the frequency domain model, voltages at two ends of a branch where a transformer neutral point is located in an urban power grid are calculated according to a connection structure between the power grid and the subway, and distribution of current flowing through the transformer neutral point under different frequencies is calculated through ohm law, so that visual observation that discrete subway current acts on the transformer neutral point is realized.
The method for calculating the dc frequency distribution of the neutral point of the transformer is further described below with reference to fig. 3, in which the method for calculating the dc frequency distribution of the neutral point of the transformer is provided as an example for application of stray current in a subway. Fig. 3 shows a process flow chart of a method for calculating dc frequency distribution of a neutral point of a transformer applied to stray current of a subway, which specifically includes the following steps:
s302: and calculating the train speed through subway line mileage and train operation time contained in the subway network information.
Specifically, the time of the whole running process of the upper train and the lower train is recorded as t1 and t2, the total stop time t s1 and t s2 of each station in the whole running process of the upper train and the lower train are recorded, the total mileage of the subway line is S, and the average speed v av of the train is calculated to meet the following formula:
S304: and calculating the subway segment length according to the preset acquisition duration and the train speed.
S306: and dividing the subway line based on the length of the subway section to obtain the subway section.
Specifically, the mileage information of each station along the subway is recorded, the interval distance between two adjacent stations is calculated, longitudinal metals such as steel rails, drainage nets, through ground wires and the like in the interval between two adjacent stations of the subway are segmented according to the average distance l av(lav＝vav of train running per second, the number m= [ m 1,m2,…,mN-1 ] of the longitudinal metal segments in the interval between two adjacent stations is calculated and obtained through a rounding method for the interval between stations which cannot be segmented in an integer manner, N is the total number of stations, and the longitudinal metal segment length l= [ l 1,l2,…,li,…,lN-1 ] of the interval between any two adjacent stations is calculated, wherein l i＝Li/mi (i is more than or equal to 1 and less than or equal to N-1).
S308: and calculating the equivalent resistance of the subway section according to the resistance equivalent information contained in the subway network information.
Specifically, according to the number M and the length L of the longitudinal metal segments between two adjacent stations, calculating the mileage L= [ L 1,L2,…,LM ] of each segment node position of the steel rail, wherein L 1＝0,LM = S, M is the total number of the longitudinal metal segment nodes, M= Σm+1, and according to the longitudinal metal segment length and the resistance value of the longitudinal metal unit length, calculating the resistance value of each segment metal by using the ohm theorem.
S310: and constructing the subway resistance network equivalent model according to the mapping relation between the subway segments and the subway line.
Specifically, according to the number m of longitudinal metal segments, the segment length l and the metal resistance value of each segment, a subway stray current resistance network equivalent model with three longitudinal metal structures including a steel rail, a drainage network and a through ground wire is built, and the grounding resistance of the station position in the model is not more than 1 omega due to the building standard of an actual subway line.
S312: and acquiring urban power grid information, and constructing an urban power grid direct current resistance equivalent model according to the urban power grid information.
Specifically, the method comprises the steps of collecting transformer substation geographic information, transformer substation grounding resistance, transformers, power transmission lines, cable cores and direct current resistance parameters of armor (sheath) in an urban power grid, and establishing an equivalent model of the direct current resistance of the urban power grid according to the topology of the urban power grid, the grounding mode of a neutral point of the transformers and the grounding mode of the cable armor (sheath).
S314: inquiring a butt joint mode of the subway resistance network equivalent model and the city power grid direct current resistance equivalent model according to the city power grid information, and constructing a power grid-subway resistance equivalent model based on an inquiry result.
Specifically, a subway stray current resistance network equivalent model and a direct current resistance equivalent model of the urban power grid are connected according to a cable grounding mode of a transformer substation of the subway main station and the urban power grid, a cable armor unit length resistance value and an armor equivalent resistance of an incoming and outgoing line cable of the subway main station, and a unified resistance network model of the subway and the urban power grid is built.
S316: inquiring the subway network information, and determining the traction current information containing the subway train running position and the corresponding traction current.
And (3) taking 1s as an interval, recording and storing train positions P1 and P2 and corresponding traction current data I1 and I2 of each train in the whole running process of the subway uplink and downlink, and acquiring uplink traction current data I up＝[i1,i2,…,iM and downlink traction current data I down＝[j1,j2,…,jM corresponding to the subsection node position mileage L by utilizing a linear interpolation method in combination with the mileage L of the rail subsection node position.
S318: and calculating departure interval time and stop time of the subway train based on the subway network information.
Specifically, according to a subway train running chart and a timetable, the average train departure interval T and the average station stopping time DeltaT of a station are calculated.
S320: and constructing a traction current time domain distribution model according to the subway section, the running position, traction current corresponding to the running position, the departure interval duration and the stop duration.
Specifically, as shown in a schematic drawing of a traction current time domain distribution of a calculation method of a dc frequency distribution of a neutral point of a transformer in fig. 4, wherein fig. 4 (a) shows a distribution of an uplink traction current and a downlink traction current of a certain station node, for a position mileage L k (k is less than or equal to 1) of any segment node, if L k is a mileage corresponding to an x (x is less than or equal to 1) th station position, the node is named as a station node, and the uplink traction current and the downlink traction current of the station node are respectively equivalent to continuous periodic pulse signals:
Wherein I up·k(t-t0),Idown·k(t-t0) is the uplink and downlink traction current of the node k; t is a pulse period, and the value is equal to the average departure interval; delta T is the pulse width of each pulse, and the value is equal to the average stop time; t0 is the rising edge time of the first pulse, the rising edge time of the first pulse of the upward traction current is the remainder of (k+DeltaT (x-1) -1)/T, and the rising edge time of the first pulse of the downward traction current is the remainder of ((M-k) +DeltaT (N-x))/T.
In addition, as shown in a traction current time domain distribution schematic diagram of a calculation method for a dc frequency distribution of a neutral point of a transformer provided in fig. 4, wherein fig. 4 (b) shows a distribution of an uplink traction current and a downlink traction current of a certain line node, then for any segment node mileage L k (1.ltoreq.k.ltoreq.m), if L k is not a station node, the node is named as a line node, the number of stations before the node is recorded as x, and the uplink traction current and the downlink traction current of the node are respectively equivalent to continuous periodic impulse signals:
Wherein I up·k(t-t0),Idowm·k is the uplink and downlink traction current of the node k; t is a pulse period, and the value is equal to the average departure interval; t0 is the time of occurrence of the first impulse, the time of occurrence of the first impulse of the uplink traction current is the remainder of (k+ [ delta ] T (x-1) -1)/T, and the time of occurrence of the first impulse of the downlink is the remainder of ((M-k) + [ delta ] T (N-x))/T. And obtaining an uplink and downlink traction current time domain distribution model corresponding to the position mileage L of the steel rail segment node through the calculation process.
S322: and carrying out Fourier transform on the traction current time domain distribution model to obtain the traction current frequency domain distribution model.
Specifically, a Fourier transform method is utilized to calculate and obtain a frequency domain distribution model of the upward and downward traction current of the railway line along the line, wherein the frequency domain distribution model of the upward and downward traction current of the station node is as follows:
wherein ω is frequency, and the line node uplink and downlink traction current frequency domain model is:
S324: and constructing a transformer neutral point direct current frequency distribution calculation model through the traction current frequency domain distribution model and the power grid-subway resistance equivalent model, and calculating transformer neutral point current frequency distribution.
Specifically, the sum of the frequency domain distribution models of the uplink traction current and the downlink traction current of the same node is used for obtaining traction current I (omega) = [ I 1(ω),I2(ω),…,IM (omega) ] of each sectional node of the rail along the subway, and the transformer neutral point direct current frequency distribution calculation model is obtained by combining a unified resistance network model of the subway and the urban power grid as shown in a schematic diagram of the transformer neutral point direct current frequency distribution calculation model of the transformer neutral point direct current frequency distribution calculation method provided by fig. 5.
According to the transformer neutral point direct current frequency distribution calculation model, a node current frequency domain matrix J (omega) = [ J c(ω),Jr(ω),J0 (omega) ] of the model is obtained, and a corresponding model node admittance matrix is Y, wherein J c (omega) is a contact net node current frequency domain model J c(ω)＝-∑I(ω),Jr (omega) is a steel rail node current frequency domain model J r(ω)＝I(ω),J0 (omega) and a model residual node J 0 (omega) = 0;
and respectively taking omega= [0,2 pi/T, 4 pi/T, 6 pi/T, …,2 pi ], calculating the voltages at two ends of a branch where a neutral point of the transformer is located under different frequency conditions by using kirchhoff theorem, and further calculating the current different frequency distribution of the neutral point of the transformer by using ohm theorem.
In summary, the subway section is obtained by calculating the train speed of the subway train based on the acquired subway network information and segmenting the subway line according to the train speed; calculating the equivalent resistance of the subway segment according to the subway network information, and constructing a subway resistance network equivalent model based on a calculation result; acquiring urban power grid information, and constructing a power grid-subway resistance equivalent model according to the urban power grid information and the subway resistance network equivalent model; constructing a traction current time domain distribution model according to the subway train traction current information and the subway segments contained in the subway network information, and constructing a traction current frequency domain distribution model according to the traction current time domain distribution model; and constructing a transformer neutral point direct current frequency distribution calculation model through the traction current frequency domain distribution model and the power grid-subway resistance equivalent model, calculating transformer neutral point current frequency distribution, intuitively displaying the time-dependent change characteristic of the neutral point direct current caused by subway stray current, and guaranteeing the accuracy of the influence of the subway stray current on the transformer direct current magnetic bias and relay protection research.
Corresponding to the above method embodiment, the present application further provides an embodiment of a transformer neutral dc frequency distribution calculating device, and fig. 6 shows a schematic structural diagram of a transformer neutral dc frequency distribution calculating device according to an embodiment of the present application. As shown in fig. 6, the apparatus includes:
The segmentation model 602 is configured to calculate the train speed of a subway train based on the acquired subway network information, and segment a subway line through the train speed to obtain a subway segment;
a model construction module 604 configured to calculate an equivalent resistance of the subway segment according to the subway network information, and construct a subway resistance network equivalent model based on a calculation result;
the model linking module 606 is configured to collect urban power grid information and construct a power grid-subway resistance equivalent model according to the urban power grid information and the subway resistance network equivalent model;
a traction current processing module 608 configured to construct a traction current time domain distribution model according to the subway train traction current information and the subway section contained in the subway network information, and construct a traction current frequency domain distribution model according to the traction current time domain distribution model;
The calculation module 610 is configured to construct a transformer neutral point direct current frequency distribution calculation model through the traction current frequency domain distribution model and the grid-subway resistance equivalent model, and calculate transformer neutral point current frequency distribution.
In an alternative embodiment, the segmentation model 602 is further configured to:
Calculating the train speed through subway line mileage and train operation time length contained in the subway network information; calculating the subway segment length according to the preset acquisition duration and the train speed; and dividing the subway line based on the length of the subway section to obtain the subway section.
In an alternative embodiment, the model building module 604 is further configured to:
Calculating the equivalent resistance of the subway section according to the equivalent resistance information contained in the subway network information; and constructing the subway resistance network equivalent model according to the mapping relation between the subway segments and the subway line.
In an alternative embodiment, the model linking module 606 is further configured to:
collecting urban power grid information; constructing a direct current resistance equivalent model of the urban power grid according to the urban power grid information; inquiring a butt joint mode of the subway resistance network equivalent model and the city power grid direct current resistance equivalent model according to the city power grid information, and constructing a power grid-subway resistance equivalent model based on an inquiry result.
In an alternative embodiment, the traction current processing module 608 is further configured to:
Inquiring the subway network information, and determining the traction current information containing the running position of the subway train and the corresponding traction current; calculating departure interval time and stop time of the subway train based on the subway network information; and constructing a traction current time domain distribution model according to the subway section, the running position, traction current corresponding to the running position, the departure interval duration and the stop duration.
In an alternative embodiment, the traction current processing module 608 is further configured to:
Inquiring a subway line train schedule contained in the subway network information; according to the query result, calculating the average value of subway train departure time in the preset time length as the departure interval time length, and the average value of arrival stop time as the stop time length.
In an alternative embodiment, the computing module 610 is further configured to:
calculating traction current frequency domain parameters corresponding to each subway segment through a traction current frequency domain model;
and constructing the transformer neutral point direct current frequency distribution calculation model by combining the traction current frequency domain parameters and the power grid-subway resistance equivalent model.
In an alternative embodiment, the traction current processing module 608 is further configured to
And carrying out Fourier transform on the traction current time domain distribution model to obtain the traction current frequency domain distribution model.
In an alternative embodiment, the computing module 610 is further configured to
Calculating the output of the DC frequency distribution calculation model of the neutral point of the transformer under the condition of different frequencies through kirchhoff's law, and obtaining the voltages at two ends of a branch where the neutral point of the transformer is located; and calculating the voltages at two ends of the branch where the neutral point of the transformer is located according to ohm law, and obtaining the current distribution of the neutral point of the transformer with different frequencies.
According to the transformer neutral point direct current frequency distribution calculating device, the train speed of a subway train is calculated based on the acquired subway network information, and a subway line is segmented through the train speed to obtain subway segments; calculating the equivalent resistance of the subway segment according to the subway network information, and constructing a subway resistance network equivalent model based on a calculation result; acquiring urban power grid information, and constructing a power grid-subway resistance equivalent model according to the urban power grid information and the subway resistance network equivalent model; constructing a traction current time domain distribution model according to the subway train traction current information and the subway segments contained in the subway network information, and constructing a traction current frequency domain distribution model according to the traction current time domain distribution model; and constructing a transformer neutral point direct current frequency distribution calculation model through the traction current frequency domain distribution model and the power grid-subway resistance equivalent model, calculating transformer neutral point current frequency distribution, intuitively displaying the time-dependent change characteristic of the neutral point direct current caused by subway stray current, and guaranteeing the accuracy of the influence of the subway stray current on the transformer direct current magnetic bias and relay protection research.
The above is a schematic scheme of the transformer neutral point dc frequency distribution calculating device of this embodiment. It should be noted that, the technical solution of the transformer neutral point dc frequency distribution calculating device and the technical solution of the above-mentioned transformer neutral point dc frequency distribution calculating method belong to the same conception, and details of the technical solution of the transformer neutral point dc frequency distribution calculating device, which are not described in detail, can be referred to the description of the technical solution of the above-mentioned transformer neutral point dc frequency distribution calculating method. Furthermore, the components in the apparatus embodiments should be understood as functional blocks that must be established to implement the steps of the program flow or the steps of the method, and the functional blocks are not actually functional partitions or separate limitations. The device claims defined by such a set of functional modules should be understood as a functional module architecture for implementing the solution primarily by means of the computer program described in the specification, and not as a physical device for implementing the solution primarily by means of hardware.
Fig. 7 illustrates a block diagram of a computing device 700 provided in accordance with an embodiment of the present application. The components of computing device 700 include, but are not limited to, memory 710 and processor 720. Processor 720 is coupled to memory 710 via bus 730, and database 750 is used to store data.
Computing device 700 also includes access device 740, access device 740 enabling computing device 700 to communicate via one or more networks 760. Examples of such networks include the Public Switched Telephone Network (PSTN), a Local Area Network (LAN), a Wide Area Network (WAN), a Personal Area Network (PAN), or a combination of communication networks such as the internet. The access device 740 may include one or more of any type of network interface, wired or wireless (e.g., a Network Interface Card (NIC)), such as an IEEE802.11 Wireless Local Area Network (WLAN) wireless interface, a worldwide interoperability for microwave access (Wi-MAX) interface, an ethernet interface, a Universal Serial Bus (USB) interface, a cellular network interface, a bluetooth interface, a Near Field Communication (NFC) interface, and so forth.
In one embodiment of the application, the above-described components of computing device 700, as well as other components not shown in FIG. 7, may also be connected to each other, such as by a bus. It should be understood that the block diagram of the computing device illustrated in FIG. 7 is for exemplary purposes only and is not intended to limit the scope of the present application. Those skilled in the art may add or replace other components as desired.
Computing device 700 may be any type of stationary or mobile computing device including a mobile computer or mobile computing device (e.g., tablet, personal digital assistant, laptop, notebook, netbook, etc.), mobile phone (e.g., smart phone), wearable computing device (e.g., smart watch, smart glasses, etc.), or other type of mobile device, or a stationary computing device such as a desktop computer or PC. Computing device 700 may also be a mobile or stationary server.
Wherein the processor 720 is configured to execute the following computer-executable instructions:
calculating the train speed of a subway train based on the acquired subway network information, and segmenting a subway line through the train speed to obtain subway segments;
Calculating the equivalent resistance of the subway segment according to the subway network information, and constructing a subway resistance network equivalent model based on a calculation result;
acquiring urban power grid information, and constructing a power grid-subway resistance equivalent model according to the urban power grid information and the subway resistance network equivalent model;
Constructing a traction current time domain distribution model according to the subway train traction current information and the subway segments contained in the subway network information, and constructing a traction current frequency domain distribution model according to the traction current time domain distribution model;
and constructing a transformer neutral point direct current frequency distribution calculation model through the traction current frequency domain distribution model and the power grid-subway resistance equivalent model, and calculating transformer neutral point current frequency distribution.
The foregoing is a schematic illustration of a computing device of this embodiment. It should be noted that, the technical solution of the computing device and the technical solution of the above-mentioned method for computing the dc frequency distribution of the neutral point of the transformer belong to the same concept, and details of the technical solution of the computing device, which are not described in detail, can be referred to the description of the technical solution of the above-mentioned method for computing the dc frequency distribution of the neutral point of the transformer.
An embodiment of the present application also provides a computer-readable storage medium storing computer instructions that, when executed by a processor, are configured to:
calculating the train speed of a subway train based on the acquired subway network information, and segmenting a subway line through the train speed to obtain subway segments;
Calculating the equivalent resistance of the subway segment according to the subway network information, and constructing a subway resistance network equivalent model based on a calculation result;
acquiring urban power grid information, and constructing a power grid-subway resistance equivalent model according to the urban power grid information and the subway resistance network equivalent model;
Constructing a traction current time domain distribution model according to the subway train traction current information and the subway segments contained in the subway network information, and constructing a traction current frequency domain distribution model according to the traction current time domain distribution model;
and constructing a transformer neutral point direct current frequency distribution calculation model through the traction current frequency domain distribution model and the power grid-subway resistance equivalent model, and calculating transformer neutral point current frequency distribution.
The above is an exemplary version of a computer-readable storage medium of the present embodiment. It should be noted that, the technical solution of the storage medium and the technical solution of the above-mentioned method for calculating the dc frequency distribution of the neutral point of the transformer belong to the same concept, and details of the technical solution of the storage medium, which are not described in detail, can be referred to the description of the technical solution of the above-mentioned method for calculating the dc frequency distribution of the neutral point of the transformer.
The embodiment of the application also provides a chip which stores a computer program, and the computer program realizes the steps of the transformer neutral point DC frequency distribution calculation method when being executed by the chip.
The foregoing describes certain embodiments of the present application. Other embodiments are within the scope of the following claims. In some cases, the actions or steps recited in the claims can be performed in a different order than in the embodiments and still achieve desirable results. In addition, the processes depicted in the accompanying figures do not necessarily require the particular order shown, or sequential order, to achieve desirable results. In some embodiments, multitasking and parallel processing are also possible or may be advantageous.
The computer instructions include computer program code that may be in source code form, object code form, executable file or some intermediate form, etc. The computer readable medium may include: any entity or device capable of carrying the computer program code, a recording medium, a U disk, a removable hard disk, a magnetic disk, an optical disk, a computer Memory, a Read-Only Memory (ROM), a random access Memory (RAM, random Access Memory), an electrical carrier signal, a telecommunications signal, a software distribution medium, and so forth. It should be noted that the computer readable medium contains content that can be appropriately scaled according to the requirements of jurisdictions in which such content is subject to legislation and patent practice, such as in certain jurisdictions in which such content is subject to legislation and patent practice, the computer readable medium does not include electrical carrier signals and telecommunication signals.
It should be noted that, for the sake of simplicity of description, the foregoing method embodiments are all expressed as a series of combinations of actions, but it should be understood by those skilled in the art that the present application is not limited by the order of actions described, as some steps may be performed in other order or simultaneously in accordance with the present application. Further, those skilled in the art will appreciate that the embodiments described in the specification are all preferred embodiments, and that the acts and modules referred to are not necessarily all required for the present application.
In the foregoing embodiments, the descriptions of the embodiments are emphasized, and for parts of one embodiment that are not described in detail, reference may be made to the related descriptions of other embodiments.
The preferred embodiments of the application disclosed above are intended only to assist in the explanation of the application. Alternative embodiments are not intended to be exhaustive or to limit the application to the precise form disclosed. Obviously, many modifications and variations are possible in light of the above teaching. The embodiments were chosen and described in order to best explain the principles of the application and the practical application, to thereby enable others skilled in the art to best understand and utilize the application. The application is limited only by the claims and the full scope and equivalents thereof.

Claims (8)

1. The method for calculating the DC frequency distribution of the neutral point of the transformer is characterized by comprising the following steps of:
calculating the train speed of a subway train based on the acquired subway network information, and segmenting a subway line through the train speed to obtain subway segments;
Calculating the equivalent resistance of the subway segment according to the subway network information, and constructing a subway resistance network equivalent model based on a calculation result;
acquiring urban power grid information, and constructing a power grid-subway resistance equivalent model according to the urban power grid information and the subway resistance network equivalent model;
Constructing a traction current time domain distribution model according to the subway train traction current information and the subway segments contained in the subway network information, and constructing a traction current frequency domain distribution model according to the traction current time domain distribution model; inquiring the subway network information and determining the traction current information comprising the running position of the subway train and the corresponding traction current; calculating departure interval time and stop time of the subway train based on the subway network information; constructing a traction current time domain distribution model according to the subway section, the running position, traction current corresponding to the running position, the departure interval duration and the stop duration;
Constructing a transformer neutral point direct current frequency distribution calculation model through the traction current frequency domain distribution model and the power grid-subway resistance equivalent model, and calculating transformer neutral point current frequency distribution; the process of constructing the transformer neutral point direct current frequency distribution calculation model is that traction current frequency domain parameters corresponding to all subway segments are calculated through a traction current frequency domain model; and constructing the transformer neutral point direct current frequency distribution calculation model by combining the traction current frequency domain parameters and the power grid-subway resistance equivalent model.
2. The method according to claim 1, wherein calculating a train speed of the subway train based on the obtained subway network information and segmenting the subway line by the train speed to obtain the subway segment comprises:
Calculating the train speed through subway line mileage and train operation time length contained in the subway network information;
Calculating the subway segment length according to the preset acquisition duration and the train speed;
And dividing the subway line based on the length of the subway section to obtain the subway section.
3. The method according to claim 1, wherein the calculating the equivalent resistance of the subway segment from the subway network information and constructing the subway resistance network equivalent model based on the calculation result includes:
Calculating the equivalent resistance of the subway section according to the equivalent resistance information contained in the subway network information;
and constructing the subway resistance network equivalent model according to the mapping relation between the subway segments and the subway line.
4. The method of claim 1, wherein the collecting urban grid information and constructing a grid-subway resistance equivalent model from the urban grid information and the subway resistance network equivalent model comprises:
collecting urban power grid information;
constructing a direct current resistance equivalent model of the urban power grid according to the urban power grid information;
Inquiring a butt joint mode of the subway resistance network equivalent model and the city power grid direct current resistance equivalent model according to the city power grid information, and constructing a power grid-subway resistance equivalent model based on an inquiry result.
5. The method of claim 1, wherein calculating departure interval duration and stop duration of the subway train based on the subway network information comprises:
inquiring a subway line train schedule contained in the subway network information;
according to the query result, calculating the average value of subway train departure time in the preset time length as the departure interval time length, and the average value of arrival stop time as the stop time length.
6. The method of claim 1, wherein said constructing a traction current frequency domain distribution model from said traction current time domain distribution model comprises:
And carrying out Fourier transform on the traction current time domain distribution model to obtain the traction current frequency domain distribution model.
7. The method of claim 1, wherein said calculating a transformer neutral current frequency distribution comprises:
calculating the output of the DC frequency distribution calculation model of the neutral point of the transformer under the condition of different frequencies through kirchhoff's law, and obtaining the voltages at two ends of a branch where the neutral point of the transformer is located;
And calculating the voltages at two ends of the branch where the neutral point of the transformer is located according to ohm law, and obtaining the current distribution of the neutral point of the transformer with different frequencies.
8. A transformer neutral point dc frequency distribution calculating device, comprising:
the system comprises a segmentation model, a control module and a control module, wherein the segmentation model is configured to calculate the train speed of a subway train based on acquired subway network information and segment a subway line through the train speed to obtain subway segments;
The model construction module is configured to calculate the equivalent resistance of the subway section according to the subway network information and construct a subway resistance network equivalent model based on a calculation result;
The model link module is configured to collect urban power grid information and construct a power grid-subway resistance equivalent model according to the urban power grid information and the subway resistance network equivalent model;
The traction current processing module is configured to construct a traction current time domain distribution model according to the subway train traction current information and the subway segments contained in the subway network information, and construct a traction current frequency domain distribution model according to the traction current time domain distribution model; inquiring the subway network information and determining the traction current information comprising the running position of the subway train and the corresponding traction current; calculating departure interval time and stop time of the subway train based on the subway network information; constructing a traction current time domain distribution model according to the subway section, the running position, traction current corresponding to the running position, the departure interval duration and the stop duration;
the calculation module is configured to construct a transformer neutral point direct current frequency distribution calculation model through the traction current frequency domain distribution model and the power grid-subway resistance equivalent model, and calculate transformer neutral point current frequency distribution; the process of constructing the transformer neutral point direct current frequency distribution calculation model is that traction current frequency domain parameters corresponding to all subway segments are calculated through a traction current frequency domain model; and constructing the transformer neutral point direct current frequency distribution calculation model by combining the traction current frequency domain parameters and the power grid-subway resistance equivalent model.
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