Intelligent secondary voltage line selection device and implementation method thereof

Abstract

The application provides a kind of intelligent secondary voltage line selection device, it is installed in PT interface screen, and all voltage control circuits in measurement group and metering group are connected, also with each connected voltage control circuit on air switch are connected, including voltage acquisition module, outlet module and CPU module;Voltage acquisition module real-time acquisition all voltage control circuit on secondary voltage and upload;CPU module according to the secondary voltage of all voltage control circuit, determine the abnormality of petroleum voltage control circuit, if there is, then each abnormal voltage control circuit and its fault phase conversion control instruction is issued to outlet module;Outlet module according to control instruction, to each abnormal voltage control circuit on air switch are controlled, to shut off each abnormal voltage control circuit on fault phase output voltage.It can improve the scientific rationality of voltage control circuit access and use to avoid the protection misoperation caused by non-protection voltage accident and cause large area power failure.

Description

Technical Field

[0001] This invention relates to the field of power grid fault detection technology, and in particular to an intelligent secondary voltage line selection device and its implementation method. Background Technology

[0002] In recent years, there have been numerous non-accidental power grid tripping events caused by secondary voltage loss in the power system, leading to protection malfunctions and affecting grid stability. The main reason lies in the unreasonable design and wiring of secondary voltage in substations. Currently, the primary voltage transformer (CT) windings in substations only have three sets of secondary windings: protection group, measurement group, and metering group. Therefore, the voltages connected to the PT interface panel are only the protection group voltage, measurement group voltage, and metering group voltage. Among them, the protection group voltage includes bus differential protection voltage, line protection voltage, and main transformer protection voltage, etc.; the measurement group voltage includes line monitoring and control voltage, main transformer monitoring and control voltage, fault recording voltage, harmonic suppression device voltage, signal relay voltage, and voltage monitoring voltage, etc.; the metering group voltage includes line electricity meter voltage, main transformer electricity meter voltage, and power quality voltage, etc.

[0003] However, in practice, circuit design flaws can cause secondary voltage loss, thus affecting the safe and stable operation of the power grid. For example, during the operation of the 110kV line bus disconnector, a high-frequency voltage is generated and resonates with the secondary harmonic suppression device, amplifying the high-frequency components and causing the secondary voltage circuit breaker to trip. However, since the harmonic suppression device is connected to the protection group voltage, if there is a design flaw in the circuit, it will cause secondary voltage loss of the protection, leading to malfunction of the 110kV automatic transfer switch.

[0004] In summary, in order to scientifically and rationally improve the voltage control circuit, it is necessary to develop an intelligent secondary voltage line selection device. This device can improve the scientific rationality of voltage control circuit access and use, and avoid large-scale power outages caused by protection malfunctions due to non-protected voltage accidents. Summary of the Invention

[0005] The technical problem to be solved by the embodiments of the present invention is to provide an intelligent secondary voltage line selection device and its implementation method, which can improve the scientific rationality of voltage control circuit access and use, and avoid large-scale power outages caused by protection malfunctions due to non-protection voltage accidents.

[0006] To address the aforementioned technical problems, this invention provides an intelligent secondary voltage line selection device. This device is installed within a PT interface panel that includes a protection group voltage control circuit, a measurement group voltage control circuit, and a metering group voltage control circuit. It is connected to all voltage control circuits included in the measurement group and metering group voltage control circuits, and also to circuit breakers pre-set on each connected voltage control circuit to enable or disable the corresponding three-phase secondary voltage output. The device includes a voltage acquisition module, an output module, and a CPU module.

[0007] One end of the voltage acquisition module is connected to all voltage control loops included in the voltage control loop of the measurement group and the voltage control loop of the metering group, and the other end is connected to the first end of the CPU module. It is used to acquire the secondary voltage output on all voltage control loops included in the voltage control loop of the measurement group and the voltage control loop of the metering group in real time and upload it to the CPU module.

[0008] The second end of the CPU module is connected to one end of the output module. It is used to determine whether at least one voltage control loop is abnormal based on the secondary voltage output of all voltage control loops in the measurement group voltage control loop and the metering group voltage control loop acquired by the voltage acquisition module. When one or more voltage control loops are found to be abnormal, each abnormal voltage control loop and its fault phase are identified. Furthermore, each abnormal voltage control loop and its fault phase are converted into corresponding control commands and sent to the output module.

[0009] The other end of the output module is connected to the circuit breakers on all voltage control circuits included in the voltage control circuit of the measurement group and the voltage control circuit of the metering group. It is used to control the circuit breakers on each abnormal voltage control circuit according to the control instructions issued by the CPU module, so as to shut off the output voltage of the corresponding fault phase on each abnormal voltage control circuit.

[0010] This also includes: a recording and alarm module; among which,

[0011] The recording and alarm module is connected to the third terminal of the CPU module, and is used to store the secondary voltages output by all voltage control loops included in the measurement group voltage control loop and the metering group voltage control loop acquired by the voltage acquisition module, as well as to store the judgment results and control commands of the CPU module; and,

[0012] If an alarm signal is received that is synchronously generated by the CPU module based on any control instruction conversion, an alarm will be triggered.

[0013] The voltage control circuit of the measurement group includes a line measurement and control voltage control circuit, a main transformer measurement and control voltage control circuit, a fault recording voltage control circuit, a harmonic elimination device voltage control circuit, a signal relay voltage control circuit, and a voltage monitoring and control circuit.

[0014] The metering group voltage control circuit includes a line electricity meter voltage control circuit, a main transformer electricity meter voltage control circuit, and a power quality voltage control circuit.

[0015] The CPU module determines abnormal voltage control circuits and their faulty phases by analyzing the potential difference between any two phases of the secondary voltage output from all voltage control circuits.

[0016] If the CPU module determines that the voltage of any one of the three phases (A, B, C) on the secondary voltage output of a certain voltage control loop is less than the first lower voltage limit or greater than the first upper voltage limit, then the voltage control loop is determined to be an abnormal voltage control loop with a single-phase fault, and the phase line in the voltage control loop whose voltage is less than the first lower voltage limit or greater than the first upper voltage limit is determined to be the faulty phase.

[0017] If the CPU module determines that the potential difference between any two phases of the three phases A, B, and C on the secondary voltage output of a certain voltage control loop is less than the second lower voltage limit or greater than the second upper voltage limit, then the voltage control loop is determined to be an abnormal voltage control loop with a phase-to-phase fault, and both phase lines in the voltage control loop with a potential difference less than the second lower voltage limit or greater than the second upper voltage limit are determined to be faulty phases.

[0018] This invention also provides a method for implementing an intelligent secondary voltage line selection device, which is implemented on an intelligent secondary voltage line selection device installed in a PT interface panel; wherein, the PT interface panel is further provided with a protection group voltage control circuit, a measurement group voltage control circuit, and a metering group voltage control circuit; the intelligent secondary voltage line selection device is connected to all voltage control circuits included in the measurement group voltage control circuit and the metering group voltage control circuit, and is also connected to a circuit breaker pre-installed on each connected voltage control circuit to conduct or cut off the corresponding three-phase secondary voltage output; the method includes the following steps:

[0019] The secondary voltages output from all voltage control loops included in the voltage control loop of the measurement group and the voltage control loop of the metering group are collected in real time.

[0020] Based on the secondary voltages output by all voltage control circuits in the measurement group voltage control circuit and the metering group voltage control circuit, it is determined whether at least one voltage control circuit is abnormal. When one or more voltage control circuits are found to be abnormal, each abnormal voltage control circuit and its fault phase are identified. Furthermore, based on each abnormal voltage control circuit and its fault phase, corresponding control commands are converted.

[0021] According to the control command, the circuit breaker on each abnormal voltage control loop is controlled to shut off the output voltage of the corresponding fault phase on each abnormal voltage control loop.

[0022] The method further includes:

[0023] It stores the secondary voltages output by all voltage control loops included in the voltage control loops of the measurement group and the voltage control loops of the metering group, as well as the judgment results and control commands; and,

[0024] If an alarm signal is received that is synchronously generated when any control command is switched, an alarm will be triggered.

[0025] The voltage control circuit of the measurement group includes a line measurement and control voltage control circuit, a main transformer measurement and control voltage control circuit, a fault recording voltage control circuit, a harmonic elimination device voltage control circuit, a signal relay voltage control circuit, and a voltage monitoring and control circuit.

[0026] The metering group voltage control circuit includes a line electricity meter voltage control circuit, a main transformer electricity meter voltage control circuit, and a power quality voltage control circuit.

[0027] The method further includes:

[0028] Abnormal voltage control circuits and their faulty phases are determined by analyzing the potential difference between any two phases of the secondary voltage output from all voltage control circuits.

[0029] If it is determined that the voltage of any one of the three phases (A, B, C) on the secondary voltage output of a voltage control circuit is less than the first lower voltage limit or greater than the first upper voltage limit, then the voltage control circuit is determined to be an abnormal voltage control circuit with a single-phase fault, and the phase line in the voltage control circuit whose voltage is less than the first lower voltage limit or greater than the first upper voltage limit is determined to be the faulty phase.

[0030] If it is determined that the potential difference between any two phases of the three phases A, B, and C on the secondary voltage output of a certain voltage control circuit is less than the second lower voltage limit or greater than the second upper voltage limit, then the voltage control circuit is determined to be an abnormal voltage control circuit with a phase-to-phase fault, and both phase lines in the voltage control circuit with a potential difference less than the second lower voltage limit or greater than the second upper voltage limit are determined to be faulty phases.

[0031] Implementing the embodiments of the present invention has the following beneficial effects:

[0032] The intelligent secondary voltage line selection device of the present invention is based on the secondary voltage output of all voltage control circuits included in the voltage control circuit of the measurement group and the voltage control circuit of the metering group within the PT interface panel. It determines whether at least one voltage control circuit is abnormal. If so, it identifies each abnormal voltage control circuit and its faulty phase, and further converts it into control commands to control the circuit breakers on all abnormal voltage control circuits, thereby shutting off the output voltage of the corresponding faulty phase on all abnormal voltage control circuits. This can improve the scientific rationality of voltage control circuit access and use, and avoid large-scale power outages caused by protection malfunctions due to non-protection voltage accidents. Attached Figure Description

[0033] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, obtaining other drawings based on these drawings without creative effort still falls within the scope of the present invention.

[0034] Figure 1 This is a schematic diagram of the system structure of an intelligent secondary voltage line selection device provided in an embodiment of the present invention;

[0035] Figure 2 This is an application scenario diagram of an intelligent secondary voltage line selection device provided in an embodiment of the present invention;

[0036] Figure 3 A flowchart illustrating a method for implementing an intelligent secondary voltage line selection device according to an embodiment of the present invention. Detailed Implementation

[0037] To make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings.

[0038] like Figure 1As shown in this embodiment of the invention, an intelligent secondary voltage line selection device is installed in a PT interface panel (not shown) pre-configured with protection group voltage control circuits, measurement group voltage control circuits, and metering group voltage control circuits. It is connected to all voltage control circuits (not shown) included in the measurement group and metering group voltage control circuits, and also to circuit breakers (or voltage connecting pieces, not shown) pre-configured on each connected voltage control circuit to turn on or off the corresponding three-phase secondary voltage output. The measurement group voltage control circuits include, but are not limited to, line measurement and control voltage control circuits, main transformer measurement and control voltage control circuits, fault recording voltage control circuits, harmonic suppression device voltage control circuits, signal relay voltage control circuits, and voltage monitoring control circuits. The metering group voltage control circuits include, but are not limited to, line electricity meter voltage control circuits, main transformer electricity meter voltage control circuits, and power quality voltage control circuits.

[0039] At this time, the intelligent secondary voltage line selection device includes a voltage acquisition module 1, an output module 3, and a CPU module 2; wherein,

[0040] One end of the voltage acquisition module 1 is connected to all voltage control loops included in the voltage control loop of the measurement group and the voltage control loop of the metering group, and the other end is connected to the first end of the CPU module 2. It is used to acquire the secondary voltage output on all voltage control loops included in the voltage control loop of the measurement group and the voltage control loop of the metering group in real time and upload it to the CPU module 2.

[0041] The second end of CPU module 2 is connected to one end of output module 3. It is used to determine whether at least one voltage control loop is abnormal based on the secondary voltages output from all voltage control loops in the measurement group and metering group voltage control loops acquired by voltage acquisition module 1. When one or more voltage control loops are found to be abnormal, each abnormal voltage control loop and its faulty phase are identified. Furthermore, based on each abnormal voltage control loop and its faulty phase, corresponding control commands are converted and sent to output module 2. It should be noted that CPU module 2 determines the abnormal voltage control loop and its faulty phase by measuring the potential difference between each phase voltage and / or any two phase voltages on the secondary voltages output from all voltage control loops. If module 2 determines that the voltage of any one of the three phases (A, B, C) on the secondary voltage output of a voltage control loop is less than the first lower voltage limit or greater than the first upper voltage limit, then the voltage control loop is determined to be an abnormal voltage control loop with a single-phase fault, and the phase line in the voltage control loop with a voltage less than the first lower voltage limit or greater than the first upper voltage limit is determined to be the faulty phase; or, if CPU module 2 determines that the potential difference between any two phases (A, B, C) on the secondary voltage output of a voltage control loop is less than the second lower voltage limit or greater than the second upper voltage limit, then the voltage control loop is determined to be an abnormal voltage control loop with a phase-to-phase fault, and the two phase lines in the voltage control loop with a potential difference less than the second lower voltage limit or greater than the second upper voltage limit are both faulty phases.

[0042] The other end of the output module 3 is connected to the circuit breakers on all voltage control circuits included in the measurement group voltage control circuit and the metering group voltage control circuit. This allows it to control the circuit breakers on each abnormal voltage control circuit according to the control commands issued by the CPU module 2, thereby shutting off the output voltage of the corresponding faulty phase in each abnormal voltage control circuit. It should be noted that the circuit breakers can be flexibly designed according to actual conditions; for example, one circuit breaker can be installed on each of the A, B, and C phases of the secondary voltage, or one circuit breaker can be installed on each of the A, B, and C phases.

[0043] It is understandable that, considering that when the protection group voltage (i.e., the secondary voltage output on the protection group voltage control circuit) is abnormal, the protection device will make the judgment and isolate and cut off the fault. Therefore, the intelligent secondary voltage line selection device of the present invention can also perform real-time voltage monitoring through the voltage acquisition module 1, but does not need to isolate and cut off the fault in the protection group voltage control circuit through the output module 3.

[0044] In this embodiment of the invention, the intelligent secondary voltage line selection device further includes: a recording and alarm module 4; wherein, the recording and alarm module 4 is connected to the third terminal of the CPU module 2, and is used to store the secondary voltages output by all voltage control loops included in the measurement group voltage control loop and the metering group voltage control loop acquired by the voltage acquisition module 1, and to store the judgment results and control commands of the CPU module 2; and,

[0045] If an alarm signal is received that is synchronously generated by CPU module 2 based on any control instruction conversion, an alarm will be triggered.

[0046] like Figure 2 As shown, the application scenario of the intelligent secondary voltage line selection device proposed in the embodiment of the present invention will be further explained as follows:

[0047] To address the potential hazards present in the current secondary voltage circuit of the substation, the intelligent secondary voltage line selection device of this invention is added to the PT interface panel. This intelligent secondary voltage line selection device is connected in parallel to the voltage control circuits of the protection group, measurement group, and metering group within the PT interface panel, with corresponding priority levels set to 1, 2, and 3.

[0048] When a short circuit occurs in the voltage control circuit of the measurement group or metering group due to reasons other than system or human error, the voltage control circuit can be isolated according to priority, and the faulty phase voltage can be isolated. The specific device structure is as follows: Figure 2 As shown.

[0049] At this time, when the secondary voltage output on the voltage control circuit of the measurement group or metering group is abnormal, the intelligent secondary voltage line selection device of the present invention can quickly isolate the faulty phase of the abnormal voltage control circuit according to the setting value, logic, etc. performed by the CPU module 2, and record the problem to facilitate the operation and maintenance personnel to find and handle it, and issue alarm information to notify the main station personnel.

[0050] When an abnormality is involved in the voltage of the protection group (i.e., the secondary voltage output on the protection group voltage control circuit), the logic terminates and the protection device makes a judgment to isolate and clear the fault. When an abnormality occurs in the voltage of a non-protection group (i.e., the secondary voltage output on the measurement group or metering group voltage control circuit), it can be determined whether the faulty phase is single-phase or dual-phase. The protection action is selected by comparison, and the faulty phase voltage is isolated through the output module 3. At the same time, the intelligent secondary voltage line selection device of this invention collects all voltages again. When the system voltage returns to normal, the logic terminates; otherwise, the line selection logic continues to clear the faulty voltage.

[0051] It should be noted that the settings of CPU module 2 can be flexibly adjusted according to the actual situation, including voltage threshold, percentage threshold, etc., so that there are multiple settings for comparison, which will not be elaborated here.

[0052] like Figure 3 The diagram illustrates an implementation method for an intelligent secondary voltage line selection device proposed in this invention. The device is installed within a PT interface panel. The PT interface panel includes a protection group voltage control circuit, a measurement group voltage control circuit, and a metering group voltage control circuit. The intelligent secondary voltage line selection device is connected to all voltage control circuits included in the measurement group voltage control circuit and the metering group voltage control circuit, and is also connected to circuit breakers pre-installed on each connected voltage control circuit to enable or disable the corresponding three-phase secondary voltage output. The method includes the following steps:

[0053] Step S1: Real-time acquisition of the secondary voltage output from all voltage control loops included in the voltage control loop of the measurement group and the voltage control loop of the metering group;

[0054] Step S2: Based on the secondary voltages output by all voltage control circuits in the measurement group voltage control circuit and the metering group voltage control circuit, determine whether at least one voltage control circuit is abnormal. When one or more voltage control circuits are found to be abnormal, identify each abnormal voltage control circuit and its fault phase. Further, convert each abnormal voltage control circuit and its fault phase into corresponding control commands.

[0055] Step S3: According to the control command, control the circuit breaker on each abnormal voltage control circuit to shut off the output voltage of the corresponding fault phase on each abnormal voltage control circuit.

[0056] The method further includes:

[0057] It stores the secondary voltages output by all voltage control loops included in the voltage control loops of the measurement group and the voltage control loops of the metering group, as well as the judgment results and control commands; and,

[0058] If an alarm signal is received that is synchronously generated when any control command is switched, an alarm will be triggered.

[0059] The voltage control circuit of the measurement group includes a line measurement and control voltage control circuit, a main transformer measurement and control voltage control circuit, a fault recording voltage control circuit, a harmonic elimination device voltage control circuit, a signal relay voltage control circuit, and a voltage monitoring and control circuit.

[0060] The metering group voltage control circuit includes a line electricity meter voltage control circuit, a main transformer electricity meter voltage control circuit, and a power quality voltage control circuit.

[0061] The method further includes:

[0062] Abnormal voltage control circuits and their faulty phases are determined by analyzing the potential difference between any two phases of the secondary voltage output from all voltage control circuits.

[0063] If it is determined that the voltage of any one of the three phases (A, B, C) on the secondary voltage output of a voltage control circuit is less than the first lower voltage limit or greater than the first upper voltage limit, then the voltage control circuit is determined to be an abnormal voltage control circuit with a single-phase fault, and the phase line in the voltage control circuit whose voltage is less than the first lower voltage limit or greater than the first upper voltage limit is determined to be the faulty phase.

[0064] If it is determined that the potential difference between any two phases of the three phases A, B, and C on the secondary voltage output of a certain voltage control circuit is less than the second lower voltage limit or greater than the second upper voltage limit, then the voltage control circuit is determined to be an abnormal voltage control circuit with a phase-to-phase fault, and both phase lines in the voltage control circuit with a potential difference less than the second lower voltage limit or greater than the second upper voltage limit are determined to be faulty phases.

[0065] Implementing the embodiments of the present invention has the following beneficial effects:

[0066] The intelligent secondary voltage line selection device of the present invention is based on the secondary voltage output of all voltage control circuits included in the voltage control circuit of the measurement group and the voltage control circuit of the metering group within the PT interface panel. It determines whether at least one voltage control circuit is abnormal. If so, it identifies each abnormal voltage control circuit and its faulty phase, and further converts it into control commands to control the circuit breakers on all abnormal voltage control circuits, thereby shutting off the output voltage of the corresponding faulty phase on all abnormal voltage control circuits. This can improve the scientific rationality of voltage control circuit access and use, and avoid large-scale power outages caused by protection malfunctions due to non-protection voltage accidents.

[0067] It is worth noting that in the above device embodiments, the various device modules are divided according to functional logic, but are not limited to the above division, as long as the corresponding functions can be achieved; in addition, the specific names of each functional module are only for easy differentiation and are not used to limit the scope of protection of the present invention.

[0068] Those skilled in the art will understand that all or part of the steps in the methods of the above embodiments can be implemented by a program instructing related hardware. The program can be stored in a computer-readable storage medium, such as ROM / RAM, disk, optical disk, etc.

[0069] The above description discloses only preferred embodiments of the present invention and should not be construed as limiting the scope of the present invention. Therefore, equivalent variations made in accordance with the claims of the present invention are still within the scope of the present invention.

Claims

1. An intelligent secondary voltage line selection device, characterized in that, It is installed in a PT interface panel that has a pre-set protection group voltage control circuit, a measurement group voltage control circuit, and a metering group voltage control circuit. It is connected to all voltage control circuits included in the measurement group voltage control circuit and the metering group voltage control circuit. It is also connected to a circuit breaker pre-set on each connected voltage control circuit to turn on or off the corresponding secondary voltage three-phase output. It includes a voltage acquisition module, an output module, and a CPU module. One end of the voltage acquisition module is connected to all voltage control loops included in the voltage control loop of the measurement group and the voltage control loop of the metering group, and the other end is connected to the first end of the CPU module. It is used to acquire the secondary voltage output on all voltage control loops included in the voltage control loop of the measurement group and the voltage control loop of the metering group in real time and upload it to the CPU module. The second end of the CPU module is connected to one end of the output module. It is used to determine whether at least one voltage control loop is abnormal based on the secondary voltage output of all voltage control loops in the measurement group voltage control loop and the metering group voltage control loop acquired by the voltage acquisition module. When one or more voltage control loops are found to be abnormal, each abnormal voltage control loop and its fault phase are identified. Furthermore, each abnormal voltage control loop and its fault phase are converted into corresponding control commands and sent to the output module. The other end of the output module is connected to the circuit breakers on all voltage control circuits included in the voltage control circuit of the measurement group and the voltage control circuit of the metering group. It is used to control the circuit breakers on each abnormal voltage control circuit according to the control instructions issued by the CPU module, so as to shut off the output voltage of the fault phase corresponding to each abnormal voltage control circuit. The CPU module determines abnormal voltage control circuits and their faulty phases by analyzing the potential difference between any two phases of the secondary voltage output from all voltage control circuits. If the CPU module determines that the voltage of any one of the three phases (A, B, C) on the secondary voltage output of a certain voltage control loop is less than the first lower voltage limit or greater than the first upper voltage limit, then the voltage control loop is determined to be an abnormal voltage control loop with a single-phase fault, and the phase line in the voltage control loop whose voltage is less than the first lower voltage limit or greater than the first upper voltage limit is determined to be the faulty phase. If the CPU module determines that the potential difference between any two phases of the three phases A, B, and C on the secondary voltage output of a certain voltage control loop is less than the second lower voltage limit or greater than the second upper voltage limit, then the voltage control loop is determined to be an abnormal voltage control loop with a phase-to-phase fault, and both phase lines in the voltage control loop with a potential difference less than the second lower voltage limit or greater than the second upper voltage limit are determined to be faulty phases.

2. The intelligent secondary voltage line selection device as described in claim 1, characterized in that, Also includes: The recording and alarm module; among which, The recording and alarm module is connected to the third terminal of the CPU module, and is used to store the secondary voltages output by all voltage control loops included in the measurement group voltage control loop and the metering group voltage control loop acquired by the voltage acquisition module, as well as to store the judgment results and control commands of the CPU module; and, If an alarm signal is received that is synchronously generated by the CPU module based on any control instruction conversion, an alarm will be triggered.

3. The intelligent secondary voltage line selection device as described in claim 1, characterized in that, The voltage control circuit of the measurement group includes a line measurement and control voltage control circuit, a main transformer measurement and control voltage control circuit, a fault recording voltage control circuit, a harmonic elimination device voltage control circuit, a signal relay voltage control circuit, and a voltage monitoring and control circuit.

4. The intelligent secondary voltage line selection device as described in claim 1, characterized in that, The metering group voltage control circuit includes a line electricity meter voltage control circuit, a main transformer electricity meter voltage control circuit, and a power quality voltage control circuit.

5. A method for implementing the intelligent secondary voltage line selection device as described in claim 1, characterized in that, It is implemented on an intelligent secondary voltage line selection device installed in a PT interface panel; wherein, the PT interface panel is also pre-set with a protection group voltage control circuit, a measurement group voltage control circuit, and a metering group voltage control circuit; the intelligent secondary voltage line selection device is connected to all voltage control circuits included in the measurement group voltage control circuit and the metering group voltage control circuit, and is also connected to the circuit breaker pre-set on each connected voltage control circuit to conduct or cut off the corresponding secondary voltage three-phase output; the method includes the following steps: The secondary voltages output from all voltage control loops included in the voltage control loop of the measurement group and the voltage control loop of the metering group are collected in real time. Based on the secondary voltages output by all voltage control circuits in the measurement group voltage control circuit and the metering group voltage control circuit, it is determined whether at least one voltage control circuit is abnormal. When one or more voltage control circuits are found to be abnormal, each abnormal voltage control circuit and its fault phase are identified. Furthermore, based on each abnormal voltage control circuit and its fault phase, corresponding control commands are converted. According to the control command, the circuit breaker on each abnormal voltage control loop is controlled to shut off the output voltage of the corresponding fault phase on each abnormal voltage control loop.

6. The method for implementing the intelligent secondary voltage line selection device as described in claim 5, characterized in that, The method further includes: It stores the secondary voltages output by all voltage control loops included in the voltage control loops of the measurement group and the voltage control loops of the metering group, as well as the judgment results and control commands; and, If an alarm signal is received that is synchronously generated when any control command is switched, an alarm will be triggered.

7. The method for implementing the intelligent secondary voltage line selection device as described in claim 5, characterized in that, The voltage control circuit of the measurement group includes a line measurement and control voltage control circuit, a main transformer measurement and control voltage control circuit, a fault recording voltage control circuit, a harmonic elimination device voltage control circuit, a signal relay voltage control circuit, and a voltage monitoring and control circuit.

8. The method for implementing the intelligent secondary voltage line selection device as described in claim 5, characterized in that, The metering group voltage control circuit includes a line electricity meter voltage control circuit, a main transformer electricity meter voltage control circuit, and a power quality voltage control circuit.

9. The method for implementing the intelligent secondary voltage line selection device as described in claim 5, characterized in that, The method further includes: Abnormal voltage control circuits and their faulty phases are determined by analyzing the potential difference between any two phases of the secondary voltage output from all voltage control circuits. If it is determined that the voltage of any one of the three phases (A, B, C) on the secondary voltage output of a voltage control circuit is less than the first lower voltage limit or greater than the first upper voltage limit, then the voltage control circuit is determined to be an abnormal voltage control circuit with a single-phase fault, and the phase line in the voltage control circuit whose voltage is less than the first lower voltage limit or greater than the first upper voltage limit is determined to be the faulty phase. If it is determined that the potential difference between any two phases of the three phases A, B, and C on the secondary voltage output of a certain voltage control circuit is less than the second lower voltage limit or greater than the second upper voltage limit, then the voltage control circuit is determined to be an abnormal voltage control circuit with a phase-to-phase fault, and both phase lines in the voltage control circuit with a potential difference less than the second lower voltage limit or greater than the second upper voltage limit are determined to be faulty phases.

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