A method and device for measuring stray current in transformer grounding steel column

Abstract

The present invention provides a method and device for measuring stray currents in transformer grounding posts. The method comprises real-time measurement of a first voltage signal between a preset height and the bottom of the grounding post, and a second voltage signal between the top and bottom of the post; determining the average resistance of the post based on the first and second voltage signals; and calculating the subway stray current flowing through the post based on the first and second voltage signals and the average resistance of the post. Without increasing the complexity of the device or addressing the limited measurement aperture of Hall effect sensors, the present invention enables precise monitoring of subway stray currents in transformers at various locations in an urban power grid, enabling more accurate assessment of the impact of DC bias magnetization.

Description

Technical Field

[0001] The present invention relates to the technical field of measuring stray current in a transformer grounding steel column, and in particular to a method and device for measuring stray current in a transformer grounding steel column. Background Art

[0002] In DC traction-powered subway systems, the presence of a current path between the tracks and the ground causes some current to leak from the tracks to the ground, generating subway stray currents. With the gradual expansion of power systems and urban rail transit systems, the subway system is becoming increasingly connected to the urban power grid. This increasing amount of subway stray current is invading the urban power grid through various channels, causing DC bias in transformers. Once this subway stray current intrudes into the transformer's neutral winding, it not only increases transformer noise, vibration, and insulation damage, but also leads to increased reactive power losses in the power system, voltage waveform distortion, and severe corrosion of urban metal pipe corridors, posing a threat to the safe and stable operation of the entire urban power grid. Therefore, it is crucial to measure subway stray currents at the neutral point of power transformers in areas such as transformers and traction substations.

[0003] There are many traditional methods for measuring transformer subway stray current, but all have shortcomings. For example, the traditional resistance measurement method not only requires an external constant current source, but also suffers from significant measurement errors when obtaining subway stray current through interval sampling. DC current measurement based on Hall effect sensors is not only susceptible to external magnetic field interference and ambient temperature changes, but is also limited by aperture size and cannot measure grounded steel poles. Open-loop Hall effect sensors also experience zero drift when measuring low currents, and the accuracy and stability of current measurements cannot be guaranteed. The use of dual-sensor mutual calibration can overcome the problem of clamp-on ammeters being affected by the open air gap, but the large size of the dual-sensor device makes subsequent installation and maintenance difficult. Summary of the Invention

[0004] The purpose of the present invention is to propose a method and device for measuring stray current in transformer grounding steel poles, so as to solve the problem of limited measurement aperture of Hall sensors without increasing the complexity of the device, and to accurately monitor the stray current of transformer subways in various places in the urban power grid, so as to more accurately evaluate the influence of DC bias magnetism.

[0005] In one aspect, a method for measuring stray current in a transformer grounding steel column is provided, comprising:

[0006] Real-time measurement of a first voltage signal between the top and bottom of a grounding steel column, and a second voltage signal between a preset height and the bottom of the grounding steel column;

[0007] determining an average resistance of the grounding steel column according to the first voltage signal and the second voltage signal;

[0008] The subway stray current flowing in the grounding steel column is calculated according to the first voltage signal, the second voltage signal and the average resistance of the grounding steel column.

[0009] Preferably, determining the average resistance of the grounding steel column according to the first voltage signal and the second voltage signal specifically includes:

[0010] determining a plurality of voltage measurement nodes according to a preset time interval value;

[0011] Acquire a first voltage signal corresponding to a plurality of voltage measurement nodes and a second voltage signal corresponding to a plurality of voltage measurement nodes;

[0012] Calculating the resistance values ​​of the grounding steel columns corresponding to the plurality of voltage measurement nodes respectively according to the first voltage signals corresponding to the plurality of voltage measurement nodes and the second voltage signals corresponding to the plurality of voltage measurement nodes;

[0013] An average value of the resistance values ​​of the grounding steel column corresponding to a plurality of voltage measurement nodes is calculated to obtain an average resistance of the grounding steel column.

[0014] Preferably, the resistance values ​​of the grounding steel columns corresponding to the multiple voltage measurement nodes are calculated according to the following formula:

[0015]

[0016] Among them, R gn Indicates the resistance value of the grounding steel column corresponding to multiple voltage measurement nodes, U 1n Indicates the first voltage signal corresponding to multiple voltage measurement nodes, U 2n represents the second voltage signal corresponding to multiple voltage measurement nodes, R0 represents a preset standard resistance, K represents the proportional coefficient of the preset height of the grounding steel column to the total length L of the grounding steel column, and n represents the serial number of the voltage measurement node.

[0017] Preferably, the preset standard resistor is a resistor set between a preset height and the bottom of the grounding steel column.

[0018] Preferably, the subway stray current flowing through the grounding steel column is calculated according to the following formula:

[0019]

[0020] Where I represents the subway stray current flowing through the grounding steel column, U1 represents the first voltage signal between the top and bottom of the grounding steel column, U2 represents the second voltage signal between the preset height and the bottom of the grounding steel column, K represents the proportional coefficient between the preset height of the grounding steel column and the total length L of the grounding steel column, R′ g It represents the average value of the resistance value of the grounding steel column.

[0021] On the other hand, a device for measuring stray current in a transformer grounding steel column is provided, which is used to implement the method for measuring stray current in a transformer grounding steel column, comprising:

[0022] A voltage measurement module is used to measure in real time a first voltage signal between the top and the bottom of the grounding steel column, and a second voltage signal between a preset height and the bottom of the grounding steel column;

[0023] A stray current calculation module is used to determine the average resistance of the grounding steel column based on the first voltage signal and the second voltage signal; and to calculate the subway stray current flowing through the grounding steel column based on the first voltage signal, the second voltage signal and the average resistance of the grounding steel column.

[0024] Preferably, the stray current calculation module is specifically configured to determine a plurality of voltage measurement nodes according to a preset time interval value;

[0025] Acquire a first voltage signal corresponding to a plurality of voltage measurement nodes and a second voltage signal corresponding to a plurality of voltage measurement nodes;

[0026] Calculating the resistance values ​​of the grounding steel columns corresponding to the plurality of voltage measurement nodes respectively according to the first voltage signals corresponding to the plurality of voltage measurement nodes and the second voltage signals corresponding to the plurality of voltage measurement nodes;

[0027] An average value of the resistance values ​​of the grounding steel column corresponding to a plurality of voltage measurement nodes is calculated to obtain an average resistance of the grounding steel column.

[0028] Preferably, the stray current calculation module is specifically configured to calculate the resistance values ​​of the grounding steel columns corresponding to the multiple voltage measurement nodes according to the following formula:

[0029]

[0030] Among them, R gn Indicates the resistance value of the grounding steel column corresponding to multiple voltage measurement nodes, U 1n Indicates the first voltage signal corresponding to multiple voltage measurement nodes, U 2nrepresents the second voltage signal corresponding to multiple voltage measurement nodes, R0 represents a preset standard resistance, K represents the proportional coefficient of the preset height of the grounding steel column to the total length L of the grounding steel column, and n represents the serial number of the voltage measurement node.

[0031] Preferably, the preset standard resistor is a resistor set between a preset height and the bottom of the grounding steel column.

[0032] Preferably, the stray current calculation module is specifically configured to calculate the subway stray current flowing through the grounding steel column according to the following formula:

[0033]

[0034] Where I represents the subway stray current flowing through the grounding steel column, U1 represents the first voltage signal between the top and bottom of the grounding steel column, U2 represents the second voltage signal between the preset height and the bottom of the grounding steel column, K represents the proportional coefficient between the preset height of the grounding steel column and the total length L of the grounding steel column, R′ g It represents the average value of the resistance value of the grounding steel column.

[0035] In summary, the implementation of the embodiments of the present invention has the following beneficial effects:

[0036] The present invention provides a method and device for measuring stray current in transformer grounding posts. Without increasing the complexity of the device or addressing the limited measurement aperture of Hall effect sensors, it enables precise monitoring of stray current in transformers and subways across urban power grids, enabling more accurate assessment of the impact of DC bias magnetic field. This method is applicable to both on-site and online monitoring of transformer grounding posts, addressing the limitations of Hall effect sensors due to aperture size and environmental factors, as well as the cumbersome and complex measurement equipment and installation associated with resistance measurement methods. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, without paying any creative work, other drawings obtained based on these drawings still fall within the scope of the present invention.

[0038] Figure 1 The figure is a schematic diagram of the main process of a method for measuring stray current in a transformer grounding steel column according to an embodiment of the present invention.

[0039] Figure 2 The figure is a schematic diagram of a voltage measurement in a transformer grounding steel column according to an embodiment of the present invention.

[0040] Figure 3 The figure is a circuit diagram of a method for measuring stray current in a transformer grounding steel column according to an embodiment of the present invention.

[0041] Figure 4 The figure is a schematic diagram of a device for measuring stray current in a transformer grounding steel column according to an embodiment of the present invention. DETAILED DESCRIPTION

[0042] In order to make the objectives, technical solutions and advantages of the present invention more clear, the present invention will be described in further detail below with reference to the accompanying drawings.

[0043] like Figure 1 FIG. 1 is a schematic diagram of an embodiment of a method for measuring stray current in a transformer grounding steel column provided by the present invention. In this embodiment, the method includes the following steps:

[0044] Real-time measurement of the first voltage signal between the top and bottom of the grounding steel column, and the second voltage signal between the preset height and the bottom of the grounding steel column; that is, the voltage signal U2 on the entire grounding steel column is obtained, and the voltage signal U1 between the height l of the grounding steel column and the bottom is obtained. It should be noted that, if Figure 2 As shown, the positive and negative electrodes of a voltmeter V2 are connected to the top of the grounded steel column and the bottom connected to the ground via wires to obtain the voltage signal U2 across the entire grounded steel column. The two ends of a standard resistor R0 and the positive and negative electrodes of a voltmeter V1 are connected to a position on the steel column at a height of 1 from the bottom and the bottom connected to the ground via wires, respectively. Voltmeter V1 is used to obtain the voltage signal U1 between the height 1 and the bottom of the grounded steel column.

[0045] Furthermore, the average resistance of the grounding steel column is determined according to the first voltage signal and the second voltage signal; that is, the grounding steel column resistance at multiple time nodes is measured and the average value is obtained to obtain R' g .

[0046] In this embodiment, first, multiple voltage measurement nodes are determined according to a preset time interval value; that is, the readings U1 and U2 of the voltmeters V1 and V2 are read once according to the preset time interval value (set to every 10 minutes in this embodiment), and R is calculated. g1 、R g2 、R g3 、R g4 and R g5 .

[0047] Secondly, first voltage signals corresponding to multiple voltage measurement nodes and second voltage signals corresponding to multiple voltage measurement nodes are obtained; resistance values ​​of the grounding steel columns corresponding to the multiple voltage measurement nodes are calculated based on the first voltage signals corresponding to the multiple voltage measurement nodes and the second voltage signals corresponding to the multiple voltage measurement nodes; specifically, the resistance values ​​of the grounding steel columns corresponding to the multiple voltage measurement nodes are calculated according to the following formula:

[0048]

[0049] Among them, R gn Indicates the resistance value of the grounding steel column corresponding to multiple voltage measurement nodes, U 1n Indicates the first voltage signal corresponding to multiple voltage measurement nodes, U 2n represents the second voltage signal corresponding to multiple voltage measurement nodes, R0 represents a preset standard resistance, K represents the proportional coefficient of the preset height of the grounding steel column to the total length L of the grounding steel column, and n represents the serial number of the voltage measurement node.

[0050] For example, according to the readings U1 and U2 of the first time node in the voltmeters V1 and V2, the resistance R of the entire grounding steel column at the first time node can be obtained. g1 for:

[0051]

[0052] Among them, K is the proportional coefficient of the height l and the total length L of the grounding steel column, U1 represents the voltage signal between the height l of the grounding steel column and the bottom, U2 represents the voltage signal on the entire grounding steel column, R0 represents the preset standard resistance, and K represents the proportional coefficient of the preset height of the grounding steel column and the total length L of the grounding steel column.

[0053] The preset standard resistance is a resistance set between a preset height and the bottom of the grounding steel column.

[0054] Next, the average value of the resistance values ​​of the grounding steel column corresponding to the multiple voltage measurement nodes is obtained to obtain the average resistance of the grounding steel column, that is, the measured grounding steel column resistance R g1 、R g2 、R g3 、R g4 and R g5 Take the average value to get R′ g .

[0055] Furthermore, the subway stray current flowing through the grounding steel column is calculated based on the first voltage signal, the second voltage signal and the average resistance of the grounding steel column. That is, the average resistance R′ of the grounding steel column is obtained. gAfter that, the original equipment connection is kept unchanged, and the subway stray current I flowing through the transformer grounding steel column can be measured in real time. Figure 3 As shown in the figure, by measuring the voltage U1 from the bottom of the grounding steel column at the preset height and the voltage signal U2 on the entire grounding steel column, the difference between the two is the voltage from the preset height to the top, that is, U2-U1. The corresponding resistance value from the preset height to the top is determined, that is, (1-K)R' g .

[0056] In this embodiment, the subway stray current flowing through the grounding steel column is calculated according to the following formula:

[0057]

[0058] Where I represents the subway stray current flowing through the grounding steel column, U1 represents the first voltage signal between the top and bottom of the grounding steel column, U2 represents the second voltage signal between the preset height and the bottom of the grounding steel column, K represents the proportional coefficient between the preset height of the grounding steel column and the total length L of the grounding steel column, R′ g It represents the average value of the resistance value of the grounding steel column.

[0059] like Figure 4 As shown, the present invention also provides a device for measuring stray current in a transformer grounding steel column, which is used to implement the method for measuring stray current in a transformer grounding steel column, comprising:

[0060] A voltage measurement module is used to measure in real time a first voltage signal between the top and the bottom of the grounding steel column, and a second voltage signal between a preset height and the bottom of the grounding steel column;

[0061] A stray current calculation module is used to determine the average resistance of the grounding steel column based on the first voltage signal and the second voltage signal; and to calculate the subway stray current flowing through the grounding steel column based on the first voltage signal, the second voltage signal and the average resistance of the grounding steel column.

[0062] In this embodiment, the stray current calculation module is specifically used to determine multiple voltage measurement nodes according to a preset time interval value;

[0063] Acquire a first voltage signal corresponding to a plurality of voltage measurement nodes and a second voltage signal corresponding to a plurality of voltage measurement nodes;

[0064] Calculating the resistance values ​​of the grounding steel columns corresponding to the plurality of voltage measurement nodes respectively according to the first voltage signals corresponding to the plurality of voltage measurement nodes and the second voltage signals corresponding to the plurality of voltage measurement nodes;

[0065] An average value of the resistance values ​​of the grounding steel column corresponding to a plurality of voltage measurement nodes is calculated to obtain an average resistance of the grounding steel column.

[0066] Specifically, the stray current calculation module is specifically configured to calculate the resistance values ​​of the grounding steel columns corresponding to the multiple voltage measurement nodes according to the following formula:

[0067]

[0068] Among them, R gn Indicates the resistance value of the grounding steel column corresponding to multiple voltage measurement nodes, U 1n Indicates the first voltage signal corresponding to multiple voltage measurement nodes, U 2n represents the second voltage signals corresponding to the multiple voltage measurement nodes, R0 represents a preset standard resistor, K represents the ratio coefficient between the preset height of the grounding steel column and the total length L of the grounding steel column, and n represents the sequence number of the voltage measurement node. The preset standard resistor is the resistance set between the preset height and the bottom of the grounding steel column.

[0069] More specifically, the stray current calculation module is configured to calculate the subway stray current flowing through the grounding steel column according to the following formula:

[0070]

[0071] Where I represents the subway stray current flowing through the grounding steel column, U1 represents the first voltage signal between the top and bottom of the grounding steel column, U2 represents the second voltage signal between the preset height and the bottom of the grounding steel column, K represents the proportional coefficient between the preset height of the grounding steel column and the total length L of the grounding steel column, R′ g It represents the average value of the resistance value of the grounding steel column.

[0072] It should be noted that the device described in the above embodiment corresponds to the method described in the above embodiment. Therefore, the parts of the device described in the above embodiment that are not described in detail can be obtained by referring to the contents of the method described in the above embodiment, and will not be repeated here.

[0073] In summary, the implementation of the embodiments of the present invention has the following beneficial effects:

[0074] The present invention provides a method and device for measuring stray current in transformer grounding posts. Without increasing the complexity of the device or addressing the limited measurement aperture of Hall effect sensors, it enables precise monitoring of stray current in transformers and subways across urban power grids, enabling more accurate assessment of the impact of DC bias magnetic field. This method is applicable to both on-site and online monitoring of transformer grounding posts, addressing the limitations of Hall effect sensors due to aperture size and environmental factors, as well as the cumbersome and complex measurement equipment and installation associated with resistance measurement methods.

[0075] The above disclosure is merely a preferred embodiment of the present invention and certainly cannot be used to limit the scope of the present invention. Therefore, equivalent changes made according to the claims of the present invention are still within the scope of the present invention.

Claims

1. A method for measuring stray current in a transformer grounding steel column, characterized in that: include: Real-time measurement of a first voltage signal between a preset height and the bottom of a grounding steel column, and a second voltage signal between the top and the bottom of the grounding steel column; determining an average resistance of the grounding steel column according to the first voltage signal and the second voltage signal; Calculating the subway stray current flowing through the grounding steel column according to the first voltage signal, the second voltage signal and the average resistance of the grounding steel column; The step of determining the average resistance of the grounding steel column according to the first voltage signal and the second voltage signal specifically includes: determining a plurality of voltage measurement nodes according to a preset time interval value; Acquire a first voltage signal corresponding to a plurality of voltage measurement nodes and a second voltage signal corresponding to a plurality of voltage measurement nodes; Calculating the resistance values ​​of the grounding steel columns corresponding to the plurality of voltage measurement nodes respectively according to the first voltage signals corresponding to the plurality of voltage measurement nodes and the second voltage signals corresponding to the plurality of voltage measurement nodes; Calculating an average value of the resistance values ​​of the grounding steel column corresponding to a plurality of voltage measurement nodes to obtain an average resistance of the grounding steel column; The resistance values ​​of the grounding steel columns corresponding to the multiple voltage measurement nodes are calculated according to the following formula: in, represents the resistance value of the grounding steel column corresponding to multiple voltage measurement nodes, represents a first voltage signal corresponding to a plurality of voltage measurement nodes, represents a second voltage signal corresponding to a plurality of voltage measurement nodes, Indicates the preset standard resistance, Indicates the preset height of the grounding steel column and the total length of the grounding steel column The proportional coefficient of n represents the serial number of the voltage measurement node; The preset standard resistor is a resistor connected in parallel between the preset height and the bottom of the grounding steel column; And, the subway stray current flowing through the grounding steel column is calculated according to the following formula: in, Indicates the subway stray current flowing through the grounded steel column, represents the first voltage signal between the top and bottom of the grounding steel column, A second voltage signal representing the voltage between the preset height and the bottom of the grounding steel column, Indicates the preset height of the grounding steel column and the total length of the grounding steel column The proportionality coefficient, It represents the average value of the resistance value of the grounding steel column.

2. A device for measuring stray current in a transformer grounding steel column, for implementing the method according to claim 1, characterized in that: include: A voltage measurement module is used to measure in real time a first voltage signal between a preset height and the bottom of a grounding steel column, and a second voltage signal between the top and the bottom of the grounding steel column; a stray current calculation module, configured to determine an average resistance of the grounding steel column according to the first voltage signal and the second voltage signal; and calculating the subway stray current flowing through the grounding steel column according to the first voltage signal, the second voltage signal, and the average resistance of the grounding steel column; Wherein, the stray current calculation module is specifically used to determine multiple voltage measurement nodes according to a preset time interval value; Acquire a first voltage signal corresponding to a plurality of voltage measurement nodes and a second voltage signal corresponding to a plurality of voltage measurement nodes; Calculating the resistance values ​​of the grounding steel columns corresponding to the plurality of voltage measurement nodes respectively according to the first voltage signals corresponding to the plurality of voltage measurement nodes and the second voltage signals corresponding to the plurality of voltage measurement nodes; Calculating an average value of the resistance values ​​of the grounding steel column corresponding to a plurality of voltage measurement nodes to obtain an average resistance of the grounding steel column; The stray current calculation module is further configured to calculate the resistance values ​​of the grounding steel columns corresponding to the multiple voltage measurement nodes according to the following formula: in, represents the resistance value of the grounding steel column corresponding to multiple voltage measurement nodes, represents a first voltage signal corresponding to a plurality of voltage measurement nodes, represents a second voltage signal corresponding to a plurality of voltage measurement nodes, Indicates the preset standard resistance, Indicates the preset height of the grounding steel column and the total length of the grounding steel column The proportional coefficient of n represents the serial number of the voltage measurement node; the preset standard resistor is a resistor connected in parallel between the preset height and the bottom of the grounding steel column; The stray current calculation module is further used to calculate the subway stray current flowing through the grounding steel column according to the following formula: in, Indicates the subway stray current flowing through the grounded steel column, represents the first voltage signal between the top and bottom of the grounding steel column, A second voltage signal representing the voltage between the preset height and the bottom of the grounding steel column, Indicates the preset height of the grounding steel column and the total length of the grounding steel column The proportionality coefficient, It represents the average value of the resistance value of the grounding steel column.

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