Current collection device and method for primary through-hole installation in distribution network

Abstract

The application discloses a current collecting device and method applied to primary through installation of power distribution network, the device comprises: a main current transformer, a small current transformer and a current voltage converter; the main current transformer collects power distribution line current and outputs secondary current of the main current transformer; the small current transformer collects the secondary current of the main current transformer and outputs secondary current of the small current transformer; the current voltage converter converts the secondary current of the small current transformer into a voltage signal, and then the power distribution line current value is obtained through an AD converter. The method comprises the following steps: collecting power distribution line current, outputting secondary current of the main current transformer, collecting the secondary current of the main current transformer, and outputting secondary current of the small current transformer; and converting the secondary current of the small current transformer into a voltage signal to obtain the power distribution line current value. The application greatly improves the measurement accuracy and dynamic measurement range of the transformer, significantly improves the measurement accuracy level of the collecting device, and meets the high-precision current measurement technical requirements of the power distribution network.

Description

Technical Field

[0001] The present application relates to the field of power distribution network detection, and specifically to a current collection device and method for primary through-hole installation in a power distribution network. Background Art

[0002] In distribution networks, traditional current transformers are typically used for protection and measurement. These two types of current transformers are typically used in on-site microcomputer protection equipment and metering equipment. In recent years, with the continuous development of distribution network construction, there is an urgent need for a quick-install, single-turn, primary through-hole (i.e., single-turn current transformer) high-precision current collector. This simple and convenient on-site installation allows for high-precision acquisition of distribution network current parameters, meeting new technical requirements for various types of distribution network status monitoring, early warning, and fault analysis.

[0003] Current current transformer design methods for power distribution networks generally employ conventional electromagnetic induction principles, where the required number of coil turns is wound around a single transformer core to achieve primary-to-secondary current conversion. Alternatively, electronic transformers based on Rogowski coils are employed, requiring complex integration circuits in the secondary circuit, leading to a more complex design. Furthermore, with both of these design principles, the transformer accuracy is reduced with a single-turn primary through-core configuration. With an open-type design, transformer accuracy becomes even more uncertain, making it difficult to meet the high-precision current measurement requirements of distribution networks. Summary of the Invention

[0004] This application proposes a current collection device and method for primary through-hole installation in a distribution network. By designing a new type of single-turn open-type installed current transformer and a new type of second-stage small current transformer, and by cascading the two-stage current transformer, the collected distribution line current is converted into a voltage signal. The voltage signal can be converted by input range matching through an AD converter to obtain the precise current value of the distribution line.

[0005] To achieve the above objectives, this application provides the following solutions:

[0006] The current collection device used for primary through-hole installation in the distribution network includes: main current transformer, small current transformer and current-voltage converter;

[0007] The output end of the main current transformer is connected in cascade to the small current transformer, and the output end of the small current transformer is connected to the input end of the current-voltage converter;

[0008] The main current transformer is used to collect the distribution line current and output the main current transformer secondary current;

[0009] The small current transformer is used to collect the secondary current of the main current transformer and output the secondary current of the small current transformer;

[0010] The current-voltage converter is used to convert the secondary current of the small current transformer into a voltage signal, and the voltage signal is used for input range matching conversion of the current value of the power distribution line through an AD converter.

[0011] Preferably, the main current transformer adopts a primary through one-turn open structure, and the main current transformer is installed on the power distribution line in a through manner.

[0012] Preferably, the main current transformer comprises a main transformer and an auxiliary transformer.

[0013] The main transformer comprises a main transformer single-turn primary winding and a main transformer secondary winding, and the main transformer single-turn primary winding constitutes a main transformer primary end.

[0014] The auxiliary transformer comprises an auxiliary transformer single-turn primary winding, an auxiliary transformer multi-turn primary winding and an auxiliary transformer secondary winding, and the auxiliary transformer single-turn primary winding constitutes an auxiliary transformer primary end.

[0015] The main transformer single-turn primary winding and the auxiliary transformer single-turn primary winding are connected in series.

[0016] One end of the main transformer secondary winding constitutes a main transformer secondary winding first output end, and the other end of the main transformer secondary winding constitutes a main transformer secondary winding second output end.

[0017] One end of the auxiliary transformer multi-turn primary winding constitutes an auxiliary transformer multi-turn primary winding first input end, and the other end of the auxiliary transformer multi-turn primary winding constitutes an auxiliary transformer multi-turn primary winding second input end.

[0018] The main transformer secondary winding second output end is connected to the auxiliary transformer multi-turn primary winding first input end.

[0019] The main transformer secondary winding first output end and the auxiliary transformer multi-turn primary winding second input end constitute an output end of the main current transformer.

[0020] Preferably, the main transformer further comprises a main core.

[0021] The main transformer secondary winding is wound on the main core.

[0022] Preferably, the main transformer secondary winding comprises a main transformer secondary winding first segment and a main transformer secondary winding second segment, and the number of turns of the main transformer secondary winding first segment and the number of turns of the main transformer secondary winding second segment are the same.

[0023] The main core comprises a first main core segment and a second main core segment, and the first main core segment and the second main core segment have the same length;

[0024] The first segment of the main transformer secondary winding is wound on the first main core segment;

[0025] The second segment of the main transformer secondary winding is wound on the second main core segment.

[0026] Preferably, the auxiliary transformer further comprises an auxiliary transformer secondary winding and an auxiliary core;

[0027] The auxiliary transformer secondary winding and the auxiliary transformer multi-turn primary winding are both wound on the auxiliary core;

[0028] An adjustable load is connected to the output end of the auxiliary transformer secondary winding, and the adjustable load is used to control the induced voltage of the main transformer.

[0029] Preferably, the auxiliary transformer multi-turn primary winding comprises a first auxiliary transformer multi-turn primary winding segment and a second auxiliary transformer multi-turn primary winding segment, and the number of turns of the first auxiliary transformer multi-turn primary winding segment is the same as the number of turns of the second auxiliary transformer multi-turn primary winding segment;

[0030] The auxiliary transformer secondary winding comprises a first auxiliary transformer secondary winding segment and a second auxiliary transformer secondary winding segment, and the number of turns of the first auxiliary transformer secondary winding segment is the same as the number of turns of the second auxiliary transformer secondary winding segment;

[0031] The auxiliary core comprises a first auxiliary core segment and a second auxiliary core segment, and the first auxiliary core segment and the second auxiliary core segment have the same length;

[0032] The first segment of the auxiliary transformer multi-turn primary winding and the first segment of the auxiliary transformer secondary winding are both wound on the first auxiliary core segment;

[0033] The second segment of the auxiliary transformer multi-turn primary winding and the second segment of the auxiliary transformer secondary winding are both wound on the second auxiliary core segment.

[0034] Preferably, the structure of the small current transformer is the same as that of the main current transformer.

[0035] Preferably, the current-voltage converter is an operational amplifier;

[0036] The input end of the operational amplifier is connected to the output end of the small current transformer;

[0037] The output end of the operational amplifier is connected to the AD converter.

[0038] The present application also discloses a current collection method applied to a primary through-hole installation of a distribution network, comprising the following steps:

[0039] Collect distribution line current and output main transformer secondary current;

[0040] Collecting the secondary current of the main current transformer and outputting the secondary current of the small current transformer;

[0041] The secondary current of the small current transformer is converted into a voltage signal, and the voltage signal is converted by an AD converter to match the input range to obtain the current value of the distribution line, thereby completing current collection.

[0042] The beneficial effects of this application are:

[0043] The present application discloses a current acquisition device and method for primary through-hole installation in a distribution network. By cascading two new current transformers and converting current into voltage, the secondary load of the main transformer is made close to a lightweight fixed load value, which greatly improves the accuracy and dynamic measurement range of the main transformer, and significantly improves the measurement accuracy of the acquisition device, meeting the technical requirements for high-precision current measurement in the distribution network, and has broad promotion space and use value. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] In order to more clearly illustrate the technical solution of the present application, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0045] Figure 1 This is a structural diagram of a current collection device for primary through-hole installation in a distribution network according to the first embodiment of the present application;

[0046] Figure 2 This is a schematic diagram of the main current transformer of the first stage in Example 1 of the present application;

[0047] Figure 3 A wiring diagram of the first-stage main current transformer secondary output terminal cascaded with the second-stage small current transformer in Example 1 of the present application;

[0048] Figure 4 This is a flow chart of the current collection method applied to the primary through-hole installation of the distribution network according to the second embodiment of the present application. DETAILED DESCRIPTION

[0049] The following will be combined with the drawings in the embodiments of this application to clearly and completely describe the technical solutions in the embodiments of this application. Obviously, the embodiments described are only part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0050] In order to make the above-mentioned purposes, features and advantages of the present application more obvious and easy to understand, the present application is further described in detail below with reference to the accompanying drawings and specific implementation methods.

[0051] Example 1

[0052] like Figure 1 As shown, this is a structural diagram of a current collection device for primary through-hole installation in a distribution network according to the first embodiment of the present application. The first embodiment adopts a three-stage structure, wherein the first stage is a main current transformer, the second stage is a small current transformer, and the third stage is a current-voltage converter.

[0053] The first-stage main current transformer adopts a primary through-hole structure and is directly installed on the distribution line. It can be divided into closed and open types. This embodiment adopts the open type. The first-stage main current transformer adopts a dual-core separation passive compensation method. Through light-load design (typical value is 0.1Ω load) and accurate calculation of winding coil matching parameters, the high accuracy level (0.05SS level) of the first-stage main current transformer is achieved.

[0054] The second-stage small current transformer and the third-stage current-voltage converter are designed as a whole and are directly placed on the PCB circuit board of the supporting secondary equipment, achieving secondary zero load and current-voltage conversion. The second-stage small current transformer reduces the secondary current output of the first-stage main current transformer to within the operating range of the third-stage current-voltage converter op amp, meeting the third-stage input requirements and achieving current-voltage conversion. At the same time, the second-stage small current transformer is equivalent to the load of the first-stage main current transformer, achieving a light-load design. The second-stage small current transformer also uses a dual-core passive compensation method to achieve high accuracy under loads close to zero ohms. At the same time, the second-stage small current transformer is designed to convert the impedance of the primary side to ≯0.1 ohms, meeting the light-load requirements of the first-stage main current transformer.

[0055] The third-stage current-to-voltage converter realizes the required voltage output by connecting a resistor of appropriate resistance in parallel, which facilitates input range matching conversion with different AD converters.

[0056] The output of the first-stage main current transformer and the input of the second-stage small current transformer are connected using a two-core cable, with the required length arranged according to the site conditions. The output end of the third-stage current-voltage converter is connected in conjunction with a resistor of appropriate resistance to achieve current-voltage conversion.

[0057] In this first embodiment, the first-stage main current transformer ratio is designed according to the actual requirements of the distribution network, and the secondary output is typically designed for 1 A. The second-stage small current transformer ratio is typically designed to be 1 A / 0.01 A. The third-stage current-to-voltage converter is connected in parallel with a 353 ohm resistor (which can be adjusted to match the actual AD input range) to achieve a rated voltage output of 3.53 V.

[0058] Figure 2 This is a schematic diagram of the main current transformer of the first stage in the first embodiment. It adopts a primary through-hole open structure, the design principle is a double-core separated passive compensation method, and adopts a main and auxiliary transformer separation structure.

[0059] Figure 2 Where Z is the load connected to the secondary side of the main current transformer, that is, the equivalent resistance of the second-stage small current transformer converted to the primary side.

[0060] The main transformer's single-turn primary winding is marked W1, and the auxiliary transformer's single-turn primary winding is marked W1'. Both use a through-the-core 1-turn winding, i.e., W1 = W1' = 1 turn. The through-the-core 1-turn winding is the cable of the existing operating line (the open-type transformer is mounted on this cable).

[0061] The main mutual inductance secondary winding is labeled W2. W2 is divided into two sections: the first and second sections of the main mutual inductance secondary winding, with breakpoints a and b. The two sections are wound around the first and second sections of the main core, respectively. That is, W2 / 2 turns are wound around the first section of the main core, and W2 / 2 turns are wound around the second section of the main core. These two sections are then connected in series. The two output terminals of the main mutual inductance secondary winding are labeled K1 and C. Terminals a and b must be connected after the main core is cut.

[0062] Z2: Coil impedance of the secondary winding W2 of the main transformer.

[0063] The auxiliary transformer's multi-turn primary winding is marked as W 2-b .W 2-b The winding is also divided into two parts, the first section of the auxiliary transformer multi-turn primary winding and the second section of the auxiliary transformer multi-turn primary winding. The middle breakpoints are marked as e and f. The two sections of winding are wound around the first section of the auxiliary iron core and the second section of the auxiliary iron core respectively. That is, W is wound around the first section of the auxiliary iron core. 2-b / 2, W is also wound on the second section of the auxiliary core 2-b / 2. The two are connected in series, with the two input terminals of the auxiliary transformer marked as terminals d and K2. Terminals ef are connected after the auxiliary iron core is cut.

[0064] Z 2-b :Multi-turn primary winding W of auxiliary transformer 2-b The coil impedance.

[0065] The secondary winding of the auxiliary transformer is marked as W b2 , W b2 The winding is also divided into two, the first section of the auxiliary transformer secondary winding and the second section of the auxiliary transformer secondary winding. The middle breakpoints are marked as g and h. The two sections of winding are also wound on the first section of the auxiliary iron core and the second section of the auxiliary iron core respectively. That is, W is wound on the first section of the auxiliary iron core. b2 / 2 turns, and W is also wound on the second section of the auxiliary core b2 / 2 turns, the two are connected in series, and the outgoing wires are marked as terminals b1 and b2. The middle breakpoint gh is connected after the auxiliary iron core is cut.

[0066] Z b2 : Auxiliary transformer secondary winding W b2 The coil impedance.

[0067] The current transformer structure adopts a double-core separation method, which facilitates the independent production and winding of each core wire package, and finally forms a complete current transformer after being connected and assembled through connecting wires.

[0068] In the first embodiment, by properly selecting the auxiliary transformer secondary load Z b The value of the main transformer secondary circuit total load (Z+Z2+Z 2-b ) The required voltage is entirely determined by the magnetic flux in the auxiliary core at W 2-b The potential induced by the winding is provided, which minimizes the main core excitation current and makes the error of the current transformer close to 0.

[0069] After derivation, the optimal compensation condition is:

[0070]

[0071] In order to easily meet the above conditions, the first embodiment adopts the following technical measures:

[0072] 1) The load of the current transformer is designed to be light, that is, Z is very small, and the impedance is generally designed to be ≯0.1 ohm;

[0073] 2) Fixed W 2-b =W b Where W b =W2-W 2-b , W b is the equivalent number of primary winding turns of the auxiliary transformer;

[0074] 3) Fixed Z = Z b ;

[0075] 4) Adopt scientific winding method, reduce leakage reactance of each winding to close to 0;

[0076] 5) Through accurate calculation, select suitable size of each winding, so that the secondary winding impedance Z b2 of the transformer is exactly equal to the total secondary circuit impedance Z2+Z 2-b , and at the same time, reduce the coil impedance value of each winding as much as possible.

[0077] 6) After cutting the transformer, polish the contact surface of the cut core to reduce the air gap of the core;

[0078] 7) The transformer adopts ratio difference and angle difference debugging line to adjust the possible error (ratio difference and angle difference) of the transformer;

[0079] Through the above technical measures, the high accuracy level technical requirements of the first stage main current transformer are realized.

[0080] In this embodiment, the rated current ratio of the open-type phase current transformer for power distribution network is designed as 600A / 1A, then W2=600 turns, W 2-b =300 turns, W b2 =300 turns, and Z=0.05 ohm.

[0081] The open-type main current transformer designed according to this principle meets the 0.05 SS level in accuracy (after investigation, the 0.05 SS level has reached the international leading level), that is:

[0082] 5%I n , 20%I n , 100%I n , 120%I n , the ratio difference is less than or equal to 0.05%, and the phase difference is less than or equal to 2'.

[0083] 1%I n , the ratio difference is less than or equal to 0.1%, and the phase difference is less than or equal to 4'.

[0084] I n is the rated current value of the current transformer.

[0085] If the rated current ratio of the zero sequence current transformer for power distribution network is designed as 100A / 1A, then W2=100 turns, W 2-b =50 turns, W b2 =50 turns, and Z=1 ohm.

[0086] The open-type zero sequence current transformer designed according to this principle meets the 0.2S level in accuracy (after investigation, the 0.2S level has reached the international leading level), that is:

[0087] 20%In 、100%I n , 120%I n 、150%I n Ratio difference ≤ 0.2%, phase difference ≤ 10'

[0088] 5%I n Ratio difference ≤ 0.35%, phase difference ≤ 15'.

[0089] 1%I n Ratio difference ≤ 0.75%, phase difference ≤ 30'.

[0090] The secondary load capacity design values ​​of the primary current transformers in the first stage are all very small, with a typical design value of a secondary load of 0.1Ω (or 1Ω). If the current is directly input to the secondary monitoring device, IV conversion is required. If it is directly connected to a resistor, the large load resistance will seriously affect the error. Therefore, this embodiment uses a zero-load conversion method.

[0091] The zero-load conversion method is designed based on the operational amplifier principle. The secondary input capacity of the operational amplifier is limited, generally a maximum of more than ten mA. Therefore, before the input current-voltage converter, the secondary input current value needs to be further reduced. The specific method is to cascade a second-stage small current transformer at the secondary output end of the above-mentioned first-stage main current transformer to further reduce the secondary current output value. The wiring schematic is shown in the figure. Figure 3 shown.

[0092] The secondary output of the second-stage small current transformer is connected to the current-voltage converter to realize the zero-load conversion method.

[0093] The zero-load conversion method uses the impedance conversion function of the operational amplifier to achieve the "zero load" of the current transformer. When the operational amplifier is in the amplification working state, a "0V" potential difference is always maintained between the + and - input terminals, which is equivalent to the secondary winding of the current transformer being directly short-circuited, that is, connected to "zero load".

[0094] In the first embodiment, the design principle of the second-stage small current transformer is also a double-core passive compensation method, and the load is designed to be 0 ohm, thereby achieving a high accuracy level of the second-stage small current transformer.

[0095] At the same time, the small current transformer of the second stage serves as the load of the main current transformer of the first stage, and the equivalent load of the small current transformer must meet the light load requirement of the main current transformer, that is,

[0096] Where Z1 is the primary winding impedance of the small current transformer, Z2 is the secondary winding impedance of the small current transformer, K b Rated transformation ratio of small current transformer.

[0097] The operational amplifier converts the small current into a voltage signal for the AD conversion circuit to perform input range matching conversion. The size of the voltage signal can be set by the resistor in parallel with the output of the operational amplifier.

[0098] In the first embodiment, the typical design value of the second-stage small current transformer is set to 1A / 0.01A, and the accuracy level meets the 0.01SS level (it has been verified that the 0.01SS level has reached the international leading level), that is:

[0099] When 5%In, 20%In, 100%In, and 120%In, the ratio difference is ≤0.01% and the phase difference is ≤0.3';

[0100] At 1% In, the ratio difference is ≤0.02% and the phase difference is ≤0.6'.

[0101] In this way, the impedance of the 1A / 0.01A second-stage small current transformer converted to the 1A side is ≤0.05 ohms, which effectively improves the accuracy level of the first-stage main current transformer.

[0102] In this embodiment 1, a new type of high-precision main current transformer with a one-turn open installation is researched and developed, and a high-precision small current transformer is researched and developed. By cascading the high-precision main current transformer with a high-precision small current transformer and a current-voltage converter, the collected distribution line current is accurately converted into a voltage signal, which greatly improves the accuracy and dynamic measurement range of the main transformer, significantly improves the measurement accuracy of the entire equipment, and meets the technical requirements for high-precision current measurement in the distribution network.

[0103] Example 2

[0104] like Figure 4 As shown in the figure, the current collection method applied to the primary through-hole installation of the distribution network in the second embodiment of the present application includes the following steps:

[0105] S102. Collect the distribution line current through the main current transformer and output the main transformer secondary current;

[0106] S104. Collecting the secondary current of the main transformer through a small current transformer and outputting the secondary current of the small current transformer;

[0107] S106. Convert the secondary current of the small current transformer into a voltage signal through a current-to-voltage converter. The voltage signal is used to perform input range matching conversion through an AD converter to obtain the current value of the distribution line, thereby completing current acquisition.

[0108] The above-described embodiments are merely intended to describe the preferred modes of the present application, and are not intended to limit the scope of the present application. Various modifications and improvements of the present application made by those skilled in the art are intended to fall within the scope of the present application defined in the claims.

Claims

1. A current collection device used for primary through-hole installation in a distribution network, characterized in that: include: Main current transformer, small current transformer and current-voltage converter; The output end of the main current transformer is connected in cascade to the small current transformer, and the output end of the small current transformer is connected to the input end of the current-voltage converter; The main current transformer is used to collect the current of the distribution line and output the secondary current of the main current transformer; the main current transformer adopts a primary through-core one-turn open structure, and the main current transformer is installed on the distribution line through-core; the main current transformer includes a main transformer and an auxiliary transformer; the main transformer includes a main transformer single-turn primary winding and a main transformer secondary winding, and the main transformer single-turn primary winding constitutes the main transformer primary end; the auxiliary transformer includes an auxiliary transformer single-turn primary winding, an auxiliary transformer multi-turn primary winding and an auxiliary transformer secondary winding, and the auxiliary transformer single-turn primary winding constitutes the auxiliary transformer primary end; the main transformer single-turn primary winding and the auxiliary transformer multi-turn primary winding The single-turn primary windings of the auxiliary mutual inductors are connected in series; one end of the secondary winding of the main mutual inductor constitutes the first output end of the secondary winding of the main mutual inductor, and the other end of the secondary winding of the main mutual inductor constitutes the second output end of the secondary winding of the main mutual inductor; one end of the multi-turn primary winding of the auxiliary mutual inductor constitutes the first input end of the multi-turn primary winding of the auxiliary mutual inductor, and the other end of the multi-turn primary winding of the auxiliary mutual inductor constitutes the second input end of the multi-turn primary winding of the auxiliary mutual inductor; the second output end of the secondary winding of the main mutual inductor is connected to the first input end of the multi-turn primary winding of the auxiliary mutual inductor; the first output end of the secondary winding of the main mutual inductor and the second input end of the multi-turn primary winding of the auxiliary mutual inductor constitute the output end of the main current transformer; The small current transformer is used to collect the secondary current of the main current transformer and output the secondary current of the small current transformer; ； Among them, Z b is the secondary load of the auxiliary transformer, Z b2 Auxiliary transformer secondary winding W b2 The coil impedance, Z is the load connected to the secondary side of the main current transformer, Z2 is the coil impedance of the secondary winding W2 of the main transformer, and Z 2-b The auxiliary transformer multi-turn primary winding W 2-b Coil impedance, W b2 is the secondary winding of the auxiliary transformer, W 2-b The auxiliary transformer multi-turn primary winding, W b is the equivalent number of primary winding turns of the auxiliary transformer, W b =W2-W 2-b ; The current-to-voltage converter is used to convert the secondary current of the small current transformer into a voltage signal, and the voltage signal is used to obtain the current value of the distribution line through input range matching conversion through an AD converter; the current-to-voltage converter adopts an operational amplifier; the input end of the operational amplifier is connected to the output end of the small current transformer; the output end of the operational amplifier is connected to the AD converter.

2. The current collection device for primary through-hole installation in a distribution network according to claim 1, characterized in that: The main mutual inductor also includes a main iron core; The secondary winding of the main mutual inductor is wound on the main iron core.

3. The current collection device for primary through-hole installation in a distribution network according to claim 2, characterized in that: The main transformer secondary winding includes a main transformer secondary winding first section and a main transformer secondary winding second section, and the number of turns of the main transformer secondary winding first section is the same as the number of turns of the main transformer secondary winding second section; The main iron core comprises a first main iron core section and a second main iron core section, and the first main iron core section and the second main iron core section are of the same length; The first section of the secondary winding of the main mutual inductor is wound on the first section of the main iron core; The second section of the secondary winding of the main transformer is wound on the second section of the main iron core.

4. The current collection device for primary through-hole installation in a distribution network according to claim 2, characterized in that: The auxiliary transformer also includes an auxiliary transformer secondary winding and an auxiliary iron core; The auxiliary transformer secondary winding and the auxiliary transformer multi-turn primary winding are both wound on the auxiliary iron core; The output end of the secondary winding of the auxiliary transformer is connected to an adjustable load, and the adjustable load is used to control the induced voltage of the main transformer.

5. The current collection device for primary through-hole installation in a power distribution network according to claim 4, characterized in that: The auxiliary transformer multi-turn primary winding includes a first section of the auxiliary transformer multi-turn primary winding and a second section of the auxiliary transformer multi-turn primary winding, and the number of turns of the first section of the auxiliary transformer multi-turn primary winding is the same as the number of turns of the second section of the auxiliary transformer multi-turn primary winding; The auxiliary transformer secondary winding includes a first section of the auxiliary transformer secondary winding and a second section of the auxiliary transformer secondary winding, and the number of turns of the first section of the auxiliary transformer secondary winding is the same as the number of turns of the second section of the auxiliary transformer secondary winding; The auxiliary iron core comprises a first auxiliary iron core section and a second auxiliary iron core section, and the first auxiliary iron core section and the second auxiliary iron core section are equal in length; The first section of the auxiliary transformer multi-turn primary winding and the first section of the auxiliary transformer secondary winding are both wound on the first section of the auxiliary iron core; The second section of the auxiliary transformer multi-turn primary winding and the second section of the auxiliary transformer secondary winding are both wound on the second section of the auxiliary iron core.

6. The current collection device for primary through-hole installation in a distribution network according to claim 1, characterized in that: The structure of the small current transformer is the same as that of the main current transformer.

7. A current collection method for a primary through-hole installation in a distribution network, wherein the current collection method uses the current collection device according to any one of claims 1 to 6, characterized in that: The steps include: Collect distribution line current and output main transformer secondary current; Collecting the secondary current of the main current transformer and outputting the secondary current of the small current transformer; The secondary current of the small current transformer is converted into a voltage signal through a current-voltage converter, and the voltage signal is converted into the current value of the distribution line through an AD converter for input range matching, thereby completing current collection.

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