A low-voltage ac ring network detection system for a station

Abstract

The application provides a low-voltage AC ring network detection system for a station, comprising a low-voltage carrier generator and a low-voltage carrier receiver arranged on two low-voltage busbars in a substation respectively and achieving mutual communication; three-phase different low-voltage pulse carrier signals are generated by a carrier transmitting circuit in the low-voltage carrier generator corresponding to A phase, B phase and C phase of the connected busbar respectively and transmitted in turn with fixed interval time; a carrier receiving and judging circuit in the low-voltage carrier receiver receives the low-voltage pulse carrier signals transmitted by the low-voltage carrier generator periodically based on a predetermined polling period, and when at least one low-voltage pulse carrier signal is received in a certain polling period, it is judged that the AC ring network exists and the phase of the low-voltage pulse carrier signal corresponding to the phase line on the carrier transmitting circuit is analyzed to determine the phase of the AC ring network. The application can quickly, efficiently and accurately judge the existence of the ring network of the station power system.

Description

Technical Field

[0001] This invention relates to the field of power detection technology, and in particular to a low-voltage AC ring network detection system for substation power supply. Background Technology

[0002] The substation auxiliary power system is used to supply power to the loads within the substation. This system consists of a station auxiliary transformer that converts 10kV or 20kV high voltage to 380V low voltage. Its structure typically employs a double busbar connection and separate operation. If the 10kV or 20kV high-voltage side operates separately and the 380V low-voltage side operates in parallel, a voltage difference on the high-voltage side will generate a loop current on the low-voltage side. This is especially true when a fault occurs on a section of the high-voltage busbar; the voltage of the faulty busbar is pulled down, resulting in a large voltage difference on the low-voltage side, easily generating a large loop current (typically reaching 600A or more). This can cause the substation's AC auxiliary system to trip, resulting in a loss of AC power within the substation. In more severe cases, it can lead to equipment burnout and escalation of the accident, posing safety hazards.

[0003] Currently, some low-voltage ring network detection technologies exist. For example, the invention patent with application publication number CN105021942B, entitled "A Method and System for Detecting Faults in a Neutral-Wire Connected Ring Network," involves adding a special signal to the neutral wire of a certain AC busbar and then measuring the signal on the neutral wires of all buses. If the neutral wire without the special signal shows the same signal as the neutral wire with the added signal, it is determined that an AC ring network exists; otherwise, it is determined that no AC ring network exists. However, this invention patent is highly susceptible to interference, especially since the neutral and ground wires are connected together on the low-voltage side of the station power system. The special signal can flow through the ground on the neutral wire, leading to incorrect judgment results. For example, the utility model patent with application publication number CN206892243U, entitled "Intelligent Detection Device for Low-Voltage AC Ring Network of Station Power Transformer", determines the existence of AC ring network by changing the phase of a busbar during normal operation of the power AC conversion unit and measuring the current magnitude and phase relationship. However, this utility model patent cannot be applied to station power AC system. The main reason is that if a ring network exists in the station power AC system, changing the phase of a busbar will generate a ring network current that greatly affects the protection action behavior and causes a significant operational risk.

[0004] It can be seen that the existing low-voltage ring network detection technology cannot effectively monitor the abnormal parallel situation of the station power system. The main reasons are: (1) The station power load is more complex, especially the distribution is wider and there are more wirings; (2) The load and lines in the station are usually not maintained. The ring network current generated by the abnormal ring network on the low-voltage side during normal operation is small and difficult to detect.

[0005] Therefore, there is an urgent need for a low-voltage AC ring network detection system for station power supply that can quickly, efficiently and accurately determine the existence of ring networks in the station power supply system. Summary of the Invention

[0006] The technical problem to be solved by the embodiments of the present invention is to provide a low-voltage AC ring network detection system for station power supply, which can quickly, efficiently and accurately determine the existence of ring networks in station power supply.

[0007] To address the aforementioned technical problems, this invention provides a low-voltage AC ring network detection system for substation power supply, comprising: a low-voltage carrier generator and a low-voltage carrier receiver, respectively installed on two low-voltage busbars within the substation and enabling mutual communication; wherein...

[0008] The low-voltage carrier generator includes a carrier transmitting circuit; the first input terminal of the carrier transmitting circuit is connected to the A-phase line, B-phase line and C-phase line on the corresponding low-voltage bus, and is used to generate three different low-voltage pulse carrier signals corresponding to the A-phase, B-phase and C-phase of the connected bus, respectively, and transmit them in turn at a fixed interval.

[0009] The low-voltage carrier receiver includes a carrier receiving and judgment circuit. The first input terminal of the carrier receiving and judgment circuit is connected to the A-phase line, B-phase line, and C-phase line on its corresponding low-voltage bus. It is used to periodically receive the low-voltage pulse carrier signal transmitted by the low-voltage carrier generator based on a predetermined polling period. When at least one low-voltage pulse carrier signal is received within a certain polling period, it determines that an AC loop exists. Furthermore, it analyzes the phase line on the carrier transmitting circuit corresponding to each of the received low-voltage pulse carrier signals to determine the phase of the AC loop.

[0010] The low-voltage carrier transmitter further includes a first self-test and latching circuit; wherein,

[0011] The input terminal of the first self-test and interlocking circuit is connected to the A-phase, B-phase, and C-phase lines on its corresponding low-voltage bus, and the output terminal is connected to the second input terminal of the carrier transmitting circuit. This circuit is used for power-on self-test and generates first self-test information, including first self-test normal information and first self-test fault information; or

[0012] After a normal power-on self-test, if parallel operation is detected on the high-voltage side corresponding to the connected bus, the three low-voltage pulse carrier signals (phases A, B, and C) generated by the carrier transmitting circuit are blocked. Once the high-voltage side corresponding to the connected bus returns to split operation, the carrier transmitting circuit is unlocked to continue generating the three low-voltage pulse carrier signals (phases A, B, and C).

[0013] After the power-on self-test is normal, if at least one AC load is detected to be in a start-stop state on any phase line of the connected bus, the three low-voltage pulse carrier signals of phase A, phase B and phase C generated by the carrier transmitting circuit are blocked. After it is detected that no AC load is in a start-stop state on any phase line of the connected bus, the carrier transmitting circuit is unlocked to continue generating the three low-voltage pulse carrier signals of phase A, phase B and phase C.

[0014] The low-voltage carrier transmitter further includes a first communication interface circuit; wherein,

[0015] The input terminal of the first communication interface circuit is connected to the output terminal of the first self-test and latching circuit, and the output terminal is connected to the first external device. It is used to send the first self-test information generated during the self-test of the first self-test and latching circuit, as well as the first alarm information generated when the first self-test and latching circuit is in normal self-test and latches the three low-voltage pulse carrier signals of phase A, phase B and phase C generated by the carrier transmitting circuit, to the first external device.

[0016] The low-voltage carrier transmitter further includes a first display circuit; wherein,

[0017] The first display circuit is connected to the output terminal of the first self-test and latching circuit, and is used to display the first self-test information and / or the first alarm information in real time.

[0018] The low-voltage carrier transmitter further includes a first alarm circuit; wherein,

[0019] The first alarm circuit is connected to the output terminal of the first self-test and interlocking circuit, and is used to trigger an alarm when the first self-test fault information and / or the first alarm information is received.

[0020] The low-voltage carrier receiver further includes a second self-test and latching circuit; wherein,

[0021] The input terminal of the second self-test and interlocking circuit is connected to the A-phase, B-phase, and C-phase lines on its corresponding low-voltage bus, and the output terminal is connected to the second input terminal of the carrier receiving circuit. This circuit is used for power-on self-test and generates second self-test information, including normal self-test information and second self-test fault information; or

[0022] After a normal power-on self-test, if parallel operation is detected on the high-voltage side corresponding to the connected bus, the carrier receiving circuit is locked from receiving any low-voltage pulse carrier signal generated by the low-voltage carrier transmitter. Once the high-voltage side corresponding to the connected bus is detected to have returned to separate operation, the carrier receiving circuit is unlocked to continue receiving any low-voltage pulse carrier signal generated by the low-voltage carrier transmitter; or

[0023] After the power-on self-test is normal, if at least one AC load on any phase line of the connected bus is detected to be in a start-stop state, the carrier receiving circuit is locked from receiving any low-voltage pulse carrier signal generated by the low-voltage carrier transmitter. After the high-voltage side of the connected bus is detected to return to split operation, the carrier receiving circuit is unlocked to continue receiving any low-voltage pulse carrier signal generated by the low-voltage carrier transmitter.

[0024] The low-voltage carrier receiver further includes a second communication interface circuit; wherein,

[0025] The input terminal of the second communication interface circuit is connected to the output terminal of the second self-test and latching circuit and the output terminal of the carrier receiving and judgment circuit. The output terminal is connected to the second external device. The circuit is used to send the second self-test information generated during the self-test of the second self-test and latching circuit, the second alarm information generated when the second self-test and latching circuit is in normal self-test and latches the carrier receiving circuit to receive any low-voltage pulse carrier signal generated by the low-voltage carrier transmitter, and the third alarm information generated when the carrier receiving and judgment circuit determines that an AC loop exists to the second external device.

[0026] The low-voltage carrier receiver further includes a second display circuit; wherein,

[0027] The second display circuit is connected to the output terminal of the second self-test and latching circuit and the output terminal of the carrier receiving and judgment circuit, and is used to display one or more of the received second self-test information, second alarm information and third alarm information in real time.

[0028] The low-voltage carrier transmitter further includes a second alarm circuit; wherein,

[0029] The second alarm circuit is connected to the output terminal of the second self-test and latching circuit and the output terminal of the carrier receiving and judgment circuit, and is used to trigger an alarm when one or more of the second self-test fault information, the second alarm information and the third alarm information are received.

[0030] Implementing the embodiments of the present invention has the following beneficial effects:

[0031] This invention uses a carrier transmitting circuit in a low-voltage carrier generator to generate three different low-voltage pulse carrier signals corresponding to the three phases A, B, and C of the connected bus, which are transmitted alternately at fixed intervals. The carrier receiving and judgment circuit in the low-voltage carrier receiver periodically receives these signals and determines whether an AC loop exists by whether a low-voltage pulse carrier signal is received within the polling period. If a loop exists, the phase line of the low-voltage pulse carrier signal is analyzed to determine the phase of the AC loop. This allows for a fast, efficient, and accurate determination of the existence of a loop in the power supply at the substation. Attached Figure Description

[0032] 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.

[0033] Figure 1 This is a schematic diagram of a low-voltage AC ring network detection system for station power supply provided in an embodiment of the present invention;

[0034] Figure 2 This is a schematic diagram of the connection of a low-voltage AC ring network detection system for substation power supply provided in an embodiment of the present invention.

[0035] Figure 3 This is a schematic diagram of the structure of a low-voltage carrier generator in a low-voltage AC ring network detection system for station power supply, provided by an embodiment of the present invention.

[0036] Figure 4 This is a schematic diagram of the structure of a low-voltage carrier receiver in a low-voltage AC ring network detection system for station power supply, provided in 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 Figures 1 to 4 As shown in the figure, a low-voltage AC ring network detection system for substation power supply is proposed in an embodiment of the present invention, comprising: two low-voltage busbars respectively installed within the substation (e.g., Figure 2 (As shown) A low-voltage carrier generator 1 and a low-voltage carrier receiver 2 communicate with each other; wherein,

[0039] The low-voltage carrier generator 1 includes a carrier transmitting circuit 11; the first input terminal of the carrier transmitting circuit 11 is connected to its corresponding low-voltage bus (e.g., Figure 2 The A-phase line, B-phase line and C-phase line on the left low-voltage bus are all connected to generate three different low-voltage pulse carrier signals corresponding to the A-phase, B-phase and C-phase of the connected bus, and are transmitted in turn at a fixed interval (e.g. 1 second).

[0040] The low-voltage carrier receiver 2 includes a carrier receiving and judgment circuit 21; the first input terminal of the carrier receiving and judgment circuit 21 is connected to its corresponding low-voltage bus (e.g., Figure 2The A-phase, B-phase, and C-phase lines on the right-side low-voltage bus are all connected. Based on a predetermined polling period (e.g., a 3-second cycle, polling one phase line signal every 1 second, i.e., A-phase, B-phase, and C-phase are polled once every 1 second, and after a 3-second cycle, polling resumes in the order of A-phase, B-phase, and C-phase), the low-voltage pulse carrier signal transmitted by the low-voltage carrier generator 1 is periodically received. When at least one low-voltage pulse carrier signal is detected within a certain polling period, an AC loop is determined to exist. Furthermore, the phase lines corresponding to the received low-voltage pulse carrier signals on the carrier transmitting circuit 11 are analyzed to determine the phase of the AC loop. For example, if both A-phase and B-phase low-voltage pulse carrier signals are received within a certain polling period, the phases of the AC loop are determined to be A-phase and B-phase. Similarly, if only A-phase low-voltage pulse carrier signals are received within a certain polling period, the phase of the AC loop is determined to be A-phase.

[0041] It is understandable that if no low-voltage pulse carrier signal is received in a certain polling cycle, it is determined that there is no AC ring network in that polling cycle.

[0042] Therefore, it can be seen that the low-voltage AC ring network detection system of this station has the characteristics of simple implementation, real-time judgment, high reliability, and the ability to distinguish the phases of the ring network. It can help operation and maintenance personnel to respond quickly and locate faults, and effectively improve the safety and reliability of the station's power system.

[0043] In this embodiment of the invention, the low-voltage carrier transmitter 1 further includes a first self-test and latching circuit 12, a first communication interface circuit 13, a first display circuit 14, and a first alarm circuit 15; wherein,

[0044] The input terminal of the first self-test and interlocking circuit 12 is connected to the A-phase line, B-phase line, and C-phase line on its corresponding low-voltage bus, and the output terminal is connected to the second input terminal of the carrier transmitting circuit 11. It is used for power-on self-test and generates first self-test information, including first self-test normal information and first self-test fault information; or

[0045] After a normal power-on self-test, if parallel operation is detected on the high-voltage side corresponding to the connected bus, the three low-voltage pulse carrier signals (phases A, B, and C) generated by the carrier transmitting circuit 11 are blocked. Once the high-voltage side corresponding to the connected bus returns to split operation, the carrier transmitting circuit 11 is unlocked to continue generating the three low-voltage pulse carrier signals (phases A, B, and C).

[0046] After the power-on self-test is normal, if at least one AC load is detected to be in a start-stop state on any phase line of the connected bus, the three low-voltage pulse carrier signals of phase A, phase B and phase C generated by the carrier transmitting circuit 11 will be blocked. After it is detected that no AC load is in a start-stop state on any phase line of the connected bus, the carrier transmitting circuit 11 will be unlocked to continue generating the three low-voltage pulse carrier signals of phase A, phase B and phase C.

[0047] The input terminal of the first communication interface circuit 13 (such as a USB interface circuit) is connected to the output terminal of the first self-test and latching circuit 12, and the output terminal is connected to the first external device (not shown, such as a computer, mobile phone or other smart device). It is used to send the first self-test information generated during the self-test of the first self-test and latching circuit 12, as well as the first alarm information generated when the self-test of the first self-test and latching circuit 12 is normal and the three low-voltage pulse carrier signals of phase A, phase B and phase C generated by the carrier transmitting circuit 11 are latched, to the first external device.

[0048] The first display circuit 14 (such as an LED LCD screen) is connected to the output terminal of the first self-test and lockout circuit 12, and is used to display the first self-test information and / or the first alarm information in real time.

[0049] The first alarm circuit 15 (such as an alarm circuit composed of a buzzer and / or LEDs) is connected to the output terminal of the first self-test and interlocking circuit 12, and is used to trigger an alarm when the first self-test information contains the first self-test fault information and / or the first alarm information.

[0050] In this embodiment of the invention, the low-voltage carrier receiver 2 further includes a second self-test and latching circuit 22, a second communication interface circuit 23, a second display circuit 24, and a second alarm circuit 25; wherein,

[0051] The input terminal of the second self-test and interlocking circuit 22 is connected to the A-phase line, B-phase line, and C-phase line on its corresponding low-voltage bus, and the output terminal is connected to the second input terminal of the carrier receiving circuit 21. It is used for power-on self-test and generates second self-test information, including normal second self-test information and second self-test fault information; or

[0052] After a normal power-on self-test, if parallel operation is detected on the high-voltage side corresponding to the connected bus, the carrier receiving circuit 21 is locked from receiving any low-voltage pulse carrier signal generated by the low-voltage carrier transmitter 1. Once the high-voltage side corresponding to the connected bus is detected to have returned to split operation, the carrier receiving circuit 21 is unlocked to continue receiving any low-voltage pulse carrier signal generated by the low-voltage carrier transmitter 1; or

[0053] After the power-on self-test is normal, if it is detected that at least one AC load on any phase line of the connected bus is in a start-stop state, the carrier receiving circuit 21 is locked to receive any low-voltage pulse carrier signal generated by the low-voltage carrier transmitter 1. After it is detected that the high-voltage side of the connected bus is restored to split operation, the carrier receiving circuit 21 is unlocked to continue to receive any low-voltage pulse carrier signal generated by the low-voltage carrier transmitter 1.

[0054] The input terminal of the second communication interface circuit 23 (such as a USB interface circuit) is connected to the output terminal of the second self-test and latching circuit 22 and the output terminal of the carrier receiving and judgment circuit 21. The output terminal is connected to the second external device (not shown, such as a computer, mobile phone or other smart device). It is used to send the second self-test information generated by the second self-test and latching circuit 22 during self-test, the second alarm information generated when the second self-test and latching circuit 22 is normal and latching the carrier receiving circuit 21 receives any low-voltage pulse carrier signal generated by the low-voltage carrier transmitter 1, and the third alarm information generated by the carrier receiving and judgment circuit 21 when it determines that there is an AC loop network to the second external device.

[0055] The second display circuit 24 (such as an LED LCD screen) is connected to the output terminal of the second self-test and latching circuit 22 and the output terminal of the carrier receiving and judgment circuit 21, and is used to display one or more of the received second self-test information, second alarm information and third alarm information in real time.

[0056] The second alarm circuit 25 (such as an alarm circuit composed of a buzzer and / or LEDs) is connected to the output terminal of the second self-test and interlocking circuit 22 and the output terminal of the carrier receiving and judgment circuit 21. It is used to trigger an alarm when one or more of the second self-test fault information, the second alarm information and the third alarm information are received.

[0057] based on Figure 2 The application scenario of a low-voltage AC ring network detection system for substation power supply in this embodiment of the invention is further described below:

[0058] exist Figure 2 In this system, the low-voltage carrier generator 1 is installed on the left busbar of the station power system, and the low-voltage carrier receiver 2 is installed on the right busbar of the station power system.

[0059] Turn on the power supply to the low-voltage carrier generator 1, turn on the switch of the low-voltage carrier generator 1, and it will start working after a normal self-test; at the same time, turn on the power supply to the low-voltage carrier receiver 2, turn on the switch of the low-voltage carrier receiver 2, and it will start working after a normal self-test.

[0060] The low-voltage carrier generator 1 utilizes the zero-crossing characteristic of the power frequency voltage to emit three different low-voltage pulse carrier signals in turn at fixed intervals between the three phases A, B, and C. If the low-voltage carrier receiver 2 receives the low-voltage pulse carrier signals at fixed intervals, it determines that a loop network exists, and at the same time, a third alarm message is generated and reported. Furthermore, by analyzing the phase lines generated by the low-voltage pulse carrier signals, the phase of the AC loop network is determined.

[0061] If the high-voltage side of the bus connected to the low-voltage carrier generator 1 is in parallel operation, the first self-test and blocking circuit 11 of the low-voltage carrier generator 1 can be input from the high-voltage side parallel node to block the low-voltage carrier generator 1 from emitting low-voltage pulse carrier signals; similarly, if the high-voltage side of the bus connected to the low-voltage carrier receiver 2 is in parallel operation, the second self-test and blocking circuit 22 of the low-voltage carrier receiver 2 can be input from the high-voltage side parallel node to block the low-voltage carrier receiver 2 from receiving low-voltage pulse carrier signals.

[0062] If the start-up and shutdown of certain AC loads will cause significant interference to the low-voltage carrier, a blocking signal can be sent to the low-voltage carrier generator 1 or the low-voltage carrier receiver 2 when these loads start-up and shutdown, so as to achieve the effect of temporarily blocking the ring network detection, and then unlocking after the load stabilizes.

[0063] The carrier generator 1 and the carrier receiver 2 can send alarm and self-test information to the outside through the corresponding first communication interface circuit 13 and the second communication interface circuit 23, and can also perform on-site alarms through the corresponding first alarm circuit 15 and the second alarm circuit 25, and can perform human-computer interaction and information viewing through the corresponding first display circuit 14 and the second display circuit 24.

[0064] Implementing the embodiments of the present invention has the following beneficial effects:

[0065] This invention uses a carrier transmitting circuit in a low-voltage carrier generator to generate three different low-voltage pulse carrier signals corresponding to the three phases A, B, and C of the connected bus, which are transmitted alternately at fixed intervals. The carrier receiving and judgment circuit in the low-voltage carrier receiver periodically receives these signals and determines whether an AC loop exists by whether a low-voltage pulse carrier signal is received within the polling period. If a loop exists, the phase line of the low-voltage pulse carrier signal is analyzed to determine the phase of the AC loop. This allows for a fast, efficient, and accurate determination of the existence of a loop in the power supply at the substation.

[0066] It is worth noting that the various units included in the above system embodiments are only 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 unit are only for easy differentiation and are not used to limit the scope of protection of the present invention.

[0067] 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. A low-voltage AC ring network detection system for station power supply, characterized in that, include: A low-voltage carrier generator and a low-voltage carrier receiver are respectively installed on two low-voltage busbars within the substation and enable mutual communication; among them... The low-voltage carrier generator includes a carrier transmitting circuit; the first input terminal of the carrier transmitting circuit is connected to the A-phase line, B-phase line and C-phase line on the corresponding low-voltage bus, and is used to generate three different low-voltage pulse carrier signals corresponding to the A-phase, B-phase and C-phase of the connected bus, respectively, and transmit them in turn at a fixed interval. The low-voltage carrier receiver includes a carrier receiving and judgment circuit. The first input terminal of the carrier receiving and judgment circuit is connected to the A-phase line, B-phase line, and C-phase line on its corresponding low-voltage bus. It is used to periodically receive the low-voltage pulse carrier signal transmitted by the low-voltage carrier generator based on a predetermined polling period. When at least one low-voltage pulse carrier signal is received within a certain polling period, it determines that an AC loop exists. Furthermore, it analyzes the phase line on the carrier transmitting circuit corresponding to each of the received low-voltage pulse carrier signals to determine the phase of the AC loop.

2. The station power low-voltage AC ring network detection system as described in claim 1, characterized in that, The low-voltage carrier transmitter also includes a first self-test and latching circuit; wherein... The input terminal of the first self-test and interlocking circuit is connected to the A-phase, B-phase, and C-phase lines on its corresponding low-voltage bus, and the output terminal is connected to the second input terminal of the carrier transmitting circuit. This circuit is used for power-on self-test and generates first self-test information, including first self-test normal information and first self-test fault information; or After a normal power-on self-test, if parallel operation is detected on the high-voltage side corresponding to the connected bus, the three low-voltage pulse carrier signals (phases A, B, and C) generated by the carrier transmitting circuit are blocked. Once the high-voltage side corresponding to the connected bus returns to split operation, the carrier transmitting circuit is unlocked to continue generating the three low-voltage pulse carrier signals (phases A, B, and C). After the power-on self-test is normal, if at least one AC load is detected to be in a start-stop state on any phase line of the connected bus, the three low-voltage pulse carrier signals of phase A, phase B and phase C generated by the carrier transmitting circuit are blocked. After it is detected that no AC load is in a start-stop state on any phase line of the connected bus, the carrier transmitting circuit is unlocked to continue generating the three low-voltage pulse carrier signals of phase A, phase B and phase C.

3. The station power low-voltage AC ring network detection system as described in claim 2, characterized in that, The low-voltage carrier transmitter also includes a first communication interface circuit; wherein... The input terminal of the first communication interface circuit is connected to the output terminal of the first self-test and latching circuit, and the output terminal is connected to the first external device. It is used to send the first self-test information generated during the self-test of the first self-test and latching circuit, as well as the first alarm information generated when the first self-test and latching circuit is in normal self-test and latches the three low-voltage pulse carrier signals of phase A, phase B and phase C generated by the carrier transmitting circuit, to the first external device.

4. The station power low-voltage AC ring network detection system as described in claim 3, characterized in that, The low-voltage carrier transmitter also includes a first display circuit; wherein... The first display circuit is connected to the output terminal of the first self-test and latching circuit, and is used to display the first self-test information and / or the first alarm information in real time.

5. The station power low-voltage AC ring network detection system as described in claim 4, characterized in that, The low-voltage carrier transmitter also includes a first alarm circuit; wherein... The first alarm circuit is connected to the output terminal of the first self-test and interlocking circuit, and is used to trigger an alarm when the first self-test fault information and / or the first alarm information is received.

6. The station power low-voltage AC ring network detection system as described in claim 1, characterized in that, The low-voltage carrier receiver also includes a second self-test and latching circuit; wherein... The input terminal of the second self-test and interlocking circuit is connected to the A-phase, B-phase, and C-phase lines on its corresponding low-voltage bus, and the output terminal is connected to the second input terminal of the carrier receiving and judgment circuit. This circuit is used for power-on self-test and generates second self-test information, including normal self-test information and second self-test fault information; or After a normal power-on self-test, if parallel operation is detected on the high-voltage side corresponding to the connected bus, the carrier receiving and judgment circuit is locked from receiving any low-voltage pulse carrier signal generated by the low-voltage carrier transmitter. Once the high-voltage side corresponding to the connected bus is detected to have returned to separate operation, the carrier receiving and judgment circuit is unlocked to continue receiving any low-voltage pulse carrier signal generated by the low-voltage carrier transmitter; or After the power-on self-test is normal, if at least one AC load on any phase line of the connected bus is detected to be in a start-stop state, the carrier receiving and judgment circuit is locked from receiving any low-voltage pulse carrier signal generated by the low-voltage carrier transmitter. After the high-voltage side of the connected bus is detected to be restored to split operation, the carrier receiving and judgment circuit is unlocked to continue receiving any low-voltage pulse carrier signal generated by the low-voltage carrier transmitter.

7. The station power low-voltage AC ring network detection system as described in claim 6, characterized in that, The low-voltage carrier receiver also includes a second communication interface circuit; wherein... The input terminal of the second communication interface circuit is connected to the output terminal of the second self-test and latching circuit and the output terminal of the carrier receiving and judgment circuit. The output terminal is connected to the second external device. The circuit is used to send the second self-test information generated during the self-test of the second self-test and latching circuit, the second alarm information generated when the second self-test and latching circuit is in normal self-test and latches the carrier receiving and judgment circuit to receive any low-voltage pulse carrier signal generated by the low-voltage carrier transmitter, and the third alarm information generated when the carrier receiving and judgment circuit determines that an AC loop exists to the second external device.

8. The station power low-voltage AC ring network detection system as described in claim 7, characterized in that, The low-voltage carrier receiver also includes a second display circuit; wherein... The second display circuit is connected to the output terminal of the second self-test and latching circuit and the output terminal of the carrier receiving and judgment circuit, and is used to display one or more of the received second self-test information, second alarm information and third alarm information in real time.

9. The station power low-voltage AC ring network detection system as described in claim 8, characterized in that, The low-voltage carrier receiver also includes a second alarm circuit; wherein... The second alarm circuit is connected to the output terminal of the second self-test and latching circuit and the output terminal of the carrier receiving and judgment circuit, and is used to trigger an alarm when one or more of the second self-test fault information, the second alarm information and the third alarm information are received.

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