Starting and standby transformer protection system

Abstract

The invention relates to the technical field of generator-transformer group protection, and mainly discloses a starting and standby transformer protection system which comprises a protection screen unit, a sampling unit, a power and synchronization unit and a clock synchronization module. The protection screen unit is connected with two groups of tripping coils of the high-voltage side circuit breaker through the main protection screen and the auxiliary protection screen, the line protection screen is interconnected with the main protection screen through optical communication, and the system reliability is improved. A current sampling module and a voltage sampling module in the sampling unit are connected to a main protection screen differential plug-in and a main / auxiliary screen voltage plug-in respectively, so that the signal acquisition precision is guaranteed.

Description

Technical Field

[0001] The present invention relates to the technical field of generator-transformer group protection, and in particular to a generator-transformer protection system. Background Art

[0002] In modern power systems, the reliability of the starting standby transformer (STAR) protection system is crucial. Existing technologies for STAR protection systems suffer from multiple flaws: insufficient redundancy in the protection panels, a single panel failure can easily lead to system failure, and low reliability in single-coil control of the trip circuit. Sampling unit signal synchronization is poor, immunity to electromagnetic interference is weak, and voltage sampling lacks a dynamic switching mechanism. Power supply units are often single-DC, with no seamless AC backup circuit switching, making the protection system susceptible to power loss in the event of a power failure. Clock synchronization accuracy is insufficient, making it difficult to ensure consistent time across multiple panels during network synchronization. Failure protection linkage is poor, and non-electrical protection contacts are susceptible to interference. Summary of the Invention

[0003] Therefore, the technical problem to be solved by the present invention is that the existing technology has low reliability.

[0004] The above technical problems are solved by the following technical solutions: The present invention proposes a starting and standby transformer protection system, which includes: a protection screen unit: including a main protection screen, an auxiliary protection screen and a line protection screen, the main protection screen and the auxiliary protection screen are connected to the two groups of trip coils of the high-voltage side circuit breaker through a trip circuit, and the line protection screen establishes a communication connection with the main protection screen through an optical communication link; a sampling unit: including a current sampling module and a voltage sampling module, the current sampling module is connected to the differential protection plug-in of the main protection screen through a first terminal group, and the voltage sampling module is connected to the voltage plug-ins of the main protection screen and the auxiliary protection screen through a second terminal group; a power and synchronization unit: including a DC power supply circuit and an AC backup circuit, the DC power supply circuit is connected to the protection screen unit through a first-level circuit breaker branch, and the AC backup circuit is connected in parallel with the DC power supply circuit through a second-level circuit breaker; a clock synchronization module: including a satellite receiving device and a time synchronization transmission link, the satellite receiving device is connected to the time synchronization interface of the protection screen unit through an optoelectronic conversion adapter, the input end of the time synchronization transmission link is connected to the optoelectronic conversion adapter, and the output end is connected to the time synchronization interface of the protection screen unit.

[0005] In a preferred embodiment of the standby transformer protection system of the present invention: the main protection panel and the auxiliary protection panel are both connected to a main protection device, and the main protection device includes a differential protection unit, a re-voltage overcurrent protection unit and a zero-sequence protection unit; wherein, the differential protection unit is connected to the high-voltage side current signal of the current sampling module through the first terminal group, and the re-voltage overcurrent protection unit and the zero-sequence protection unit are connected to the bus voltage signal of the voltage sampling module through the second terminal group.

[0006] In a preferred embodiment of the standby transformer protection system of the present invention: the output relay assembly of the main protection device includes a first time-limited output relay and a second time-limited output relay; wherein, the contacts of the first time-limited output relay are connected to the branch circuit breaker tripping circuit, and the contacts of the second time-limited output relay are connected to the circuit breakers on each side of the main transformer.

[0007] In a preferred embodiment of the standby transformer protection system of the present invention: the line protection panel is connected to the line protection device, the line protection device is connected to the failure starting circuit of the main protection panel and the auxiliary protection panel through a control cable, and the control cable includes a voltage switching signal circuit linked to the busbar disconnector.

[0008] In a preferred embodiment of the standby transformer protection system of the present invention: the auxiliary protection screen is connected to the non-electrical quantity protection device, the non-electrical quantity protection device is connected to the transformer body sensor through a shielded cable, the heavy gas contact of the shielded cable is connected in series with the outlet relay, and the light gas contact is connected in series with the signal relay.

[0009] In a preferred embodiment of the standby transformer protection system of the present invention: the current sampling module includes a high-voltage side current transformer and a branch current transformer, the secondary winding of the high-voltage side current transformer is connected to the differential sampling channel of the main protection screen through the first terminal group, and the secondary winding of the branch current transformer is connected to the overcurrent sampling channel of the main protection screen through the third terminal group.

[0010] In a preferred embodiment of the standby transformer protection system of the present invention: the voltage sampling module includes a bus voltage transformer, and the secondary winding of the bus voltage transformer is connected to the voltage plug-in of the main protection screen and the auxiliary protection screen through the second terminal group; the voltage plug-in includes a voltage switching relay, and the coil of the voltage switching relay is connected in series with the auxiliary contact of the bus disconnector, and the voltage switching relay is used to automatically switch the voltage sampling circuit according to the status of the bus disconnector.

[0011] In a preferred embodiment of the starting and standby transformer protection system of the present invention: the rated voltage of the DC power supply circuit is DC220V; the rated voltage of the AC standby circuit is AC220V, and the DC power supply circuit and the AC standby circuit are connected in parallel through an anti-reverse diode.

[0012] In a preferred embodiment of the standby transformer protection system of the present invention: the clock synchronization module also includes a photoelectric conversion adapter, the photoelectric conversion adapter supports IRIG-B code output, the optical fiber connector of the timing transmission link adopts an FC type interface, and the transmission wavelength is 1310nm. The photoelectric conversion adapter and the timing interface of the protection screen unit are centrally connected through an optical cable terminal box.

[0013] In a preferred embodiment of the standby transformer protection system of the present invention: the main protection screen, auxiliary protection screen and line protection screen of the protection screen unit form a failure start loop network through the control cable, and any protection screen action can trigger the failure protection function of other protection screens.

[0014] The beneficial effects of the present invention are:

[0015] The proposed starting and standby transformer protection system includes a protection screen unit, a sampling unit, a power and synchronization unit, and a clock synchronization module. The protection screen unit connects to the two trip coils of the high-voltage circuit breaker via a primary and secondary protection screen. The line protection screens are interconnected with the primary protection screen via optical communication, improving system reliability. The current and voltage sampling modules in the sampling unit are connected to the differential plug-in of the primary protection screen and the voltage plug-in of the primary and secondary screens, respectively, to ensure signal acquisition accuracy.

[0016] The power and synchronization unit utilizes a 220V DC power supply circuit connected in parallel with a 220V AC backup circuit, with anti-reverse diodes ensuring stable power supply. The clock synchronization module utilizes a satellite receiver, an optoelectronic converter adapter, and an FC-type optical fiber link for precise time synchronization. The system also utilizes control cables to create a fail-safe start circuit network. Non-electrical protection utilizes shielded cables in series with relays, addressing existing issues such as low protection reliability, large sampling errors, and unstable power supply, providing comprehensive protection for both starter and backup transformers. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings of the embodiments of the present invention. Obviously, the drawings described below only relate to some embodiments of the present invention and are not intended to limit the present invention. Among them:

[0018] Figure 1 Shows the overall connection diagram of the standby transformer protection system;

[0019] Figure 2 Shows the main protection screen structure diagram of the standby transformer protection system;

[0020] Figure 3 Shows the auxiliary protection screen structure diagram of the standby transformer protection system;

[0021] Figure 4 Shows the line protection screen structure diagram of the standby transformer protection system;

[0022] Figure 5 It shows the tripping exit diagram of the auxiliary protection panel of the standby transformer protection system;

[0023] Figure 6 It shows the voltage circuit diagram of the line protection screen of the standby transformer protection system;

[0024] Figure 7 It shows the AC and DC power supply and timing circuit diagram of the line protection panel of the standby transformer protection system;

[0025] Figure 8 It shows a part of the switch input circuit of the auxiliary protection panel of the standby transformer protection system;

[0026] Figure 9 It shows another part of the switch input circuit of the auxiliary protection panel of the standby transformer protection system;

[0027] Figure 10 The main protection device diagram of the standby transformer protection system is shown;

[0028] Figure 11 Shows the structure diagram of the output relay assembly of the standby transformer protection system;

[0029] Figure 12 Shows the connection diagram between the line protection screen and the line protection device of the standby transformer protection system;

[0030] Figure 13 It shows the auxiliary protection panel and non-electrical protection device diagram of the standby transformer protection system;

[0031] Figure 14 Shows the current sampling module structure diagram of the standby transformer protection system;

[0032] Figure 15 The bus voltage transformer structure diagram of the standby transformer protection system is shown;

[0033] Figure 16 Shows the connection diagram between the coil of the voltage switching relay and the busbar disconnector of the standby transformer protection system;

[0034] Figure 17 The structure diagram of the voltage switching relay of the standby transformer protection system is shown;

[0035] Figure 18 Shows the AC current loop diagram of part of the main protection panel of the standby transformer protection system;

[0036] Figure 19 It shows the AC current loop diagram of the remaining main protection screen of the standby transformer protection system;

[0037] Figure 20 Shows the AC voltage circuit diagram of part of the main protection panel of the standby transformer protection system;

[0038] Figure 21 It shows the AC voltage circuit diagram of the remaining main protection panel of the standby transformer protection system;

[0039] Figure 22 It shows the AC and DC power supply and timing circuit diagram of the main protection panel of the standby transformer protection system;

[0040] Figure 23 Shows the lighting printed circuit diagram of the main protection screen of the standby transformer protection system;

[0041] Figure 24 Shows the clock synchronization module partial structure diagram of the standby transformer protection system;

[0042] Figure 25 The remaining structure diagram of the clock synchronization module of the standby transformer protection system is shown. DETAILED DESCRIPTION

[0043] In order to enable those skilled in the art to better understand the present invention, the present invention is further described in detail below with reference to specific embodiments and the accompanying drawings.

[0044] The terms used in the present invention are those commonly used in the art in view of the functions of the present invention, but these terms may vary according to the intentions of those skilled in the art, precedents, or new technologies in the art. In addition, specific terms may be selected by the applicant, and in such cases, their detailed meanings will be described in the detailed description of the present invention. Therefore, the terms used in the specification should not be understood as simple names, but rather as the meanings of the terms and the overall description of the present invention.

[0045] Example 1

[0046] Reference Figures 1 to 25 , which is the first embodiment of the present invention, provides a standby transformer protection system, which includes: a protection screen unit 100, a sampling unit 200, a power and synchronization unit 300 and a clock synchronization module 400.

[0047] Among them, the protection screen unit 100 includes a main protection screen 101, an auxiliary protection screen 102 and a line protection screen 103. The main protection screen 101 and the auxiliary protection screen 102 are connected to the two sets of tripping coils of the high-voltage side circuit breaker through a tripping circuit, and the line protection screen 103 establishes a communication connection with the main protection screen 101 through an optical communication link.

[0048] Specifically, the main protection screen 101 and the auxiliary protection screen 102 are connected to the two sets of trip coils of the high-voltage side circuit breaker through the trip circuit. When a fault occurs, the trip circuit can quickly control the operation of the high-voltage side circuit breaker, cut off the fault circuit in time, and ensure system safety.

[0049] The line protection screen 103 establishes a stable communication connection with the main protection screen 101 with the help of an optical communication link. This communication connection ensures that the main protection screen 101 can quickly and accurately transmit key protection signals and control instructions to the line protection screen 103, realizing real-time protection and effective monitoring of the line, and ensuring the efficient and reliable operation of the entire standby transformer protection system.

[0050] The sampling unit 200 includes a current sampling module 201 and a voltage sampling module 202. The current sampling module 201 is connected to the differential protection plug-in of the main protection screen 101 through the first terminal group, and the voltage sampling module 202 is connected to the voltage plug-ins of the main protection screen 101 and the auxiliary protection screen 102 through the second terminal group.

[0051] Specifically, the current sampling module 201 is connected to the differential protection plug-in of the main protection screen 101 through the first terminal group. This connection method enables the current signal to be accurately transmitted to the main protection screen 101, thereby realizing real-time monitoring and analysis of the current, so that protective measures can be taken quickly when the current is abnormal.

[0052] At the same time, the voltage sampling module 202 is connected to the voltage plug-ins of the main protection screen 101 and the auxiliary protection screen 102 through the second terminal group, ensuring that the voltage signal can be stably transmitted to these two key protection screens, thereby realizing continuous monitoring of the system voltage and providing reliable data support for the stable operation of the protection system.

[0053] The power and synchronization unit 300 includes a DC power supply circuit 301 and an AC backup circuit 302. The DC power supply circuit 301 is connected to the protection screen unit 100 through a first-level circuit breaker branch, and the AC backup circuit 302 is connected in parallel with the DC power supply circuit 301 through a second-level circuit breaker.

[0054] Specifically, the DC power supply circuit 301 is connected to the protection screen unit 100 through the first-level circuit breaker branch, and can provide a stable DC220V voltage to the main protection screen 101, the auxiliary protection screen 102 and the line protection screen 103. This power supply method not only ensures that the protection screen unit 100 can obtain continuous and stable power support during normal operation, but also can effectively reduce the impact of power supply fluctuations on the performance of the protection device, thereby improving the reliability and stability of the entire protection system.

[0055] At the same time, the AC backup circuit 302 is connected in parallel with the DC power supply circuit 301 through the second-level circuit breaker. This design ensures that when the DC power supply circuit 301 fails or the voltage is abnormal, the AC backup circuit 302 can be put into use quickly to provide AC220V backup power for the main protection screen 101, the auxiliary protection screen 102 and the line protection screen 103, thereby ensuring uninterrupted power supply to the protection system.

[0056] This dual power supply mechanism greatly improves the system's power supply reliability, avoids power loss to the protection system due to a single power supply failure, and thus enhances the stability of substation operation.

[0057] The clock synchronization module 400 includes a satellite receiving device 401 and a timing transmission link 402. The satellite receiving device 401 is connected to the timing interface of the protection screen unit 100 through an optoelectronic conversion adapter. The input end of the timing transmission link 402 is connected to the optoelectronic conversion adapter, and the output end is connected to the timing interface of the protection screen unit 100.

[0058] Specifically, the satellite receiving device 401 is connected to the timing interface of the protection screen unit 100 via the photoelectric conversion adapter, and can receive the precise time signal sent by the satellite, and convert the optical signal into an electrical signal with the help of the photoelectric conversion adapter to ensure the accurate transmission of the time signal.

[0059] The input end of the timing transmission link 402 is connected to the optoelectronic conversion adapter, and the output end is connected to the timing interface of the protection screen unit 100, thereby building a high-precision time signal transmission channel to ensure that the time of each device in the protection screen unit 100 can be accurately synchronized, providing a reliable clock reference for the system's fault recording, event sequence recording and other functions.

[0060] Example 2

[0061] Reference Figures 1 to 25 , which is the second embodiment of the present invention. This embodiment is different from the first embodiment in that: the main protection screen 101 and the auxiliary protection screen 102 are both connected to the main protection device 101a, and the main protection device 101a includes a differential protection unit 101a-1, a re-pressure overcurrent protection unit 101a-2 and a zero-sequence protection unit 101a-3.

[0062] Among them, the differential protection unit 101a-1 is connected to the high-voltage side current signal of the current sampling module 201 through the first terminal group, and the re-voltage overcurrent protection unit 101a-2 and the zero-sequence protection unit 101a-3 are connected to the bus voltage signal of the voltage sampling module 202 through the second terminal group.

[0063] The differential protection unit 101a-1 is connected to the current sampling module 201 via the first terminal group, enabling real-time acquisition of the high-voltage side current signal. This connection allows the differential protection unit 101a-1 to quickly detect abnormal changes in the high-voltage side current, allowing it to respond promptly to faults such as short circuits, providing rapid and effective protection for the high-voltage side of the backup transformer.

[0064] The re-voltage overcurrent protection unit 101a-2 and the zero-sequence protection unit 101a-3 are connected to the voltage sampling module 202 via a second terminal group, receiving the bus voltage signal. This design ensures that these two units can accurately monitor bus voltage fluctuations and promptly identify and handle re-voltage overcurrent and zero-sequence faults, further enhancing the reliability and comprehensiveness of the backup transformer protection system.

[0065] The outlet relay assembly 101 a - 4 of the main protection device 101 a includes a first time limit outlet relay 101 a - 4 a and a second time limit outlet relay 101 a - 4 b .

[0066] Among them, the contacts of the first time limit output relay 101a-4a are connected to the tripping circuit of the branch circuit breaker, and the contacts of the second time limit output relay 101a-4b are connected to the tripping circuits of the circuit breakers on each side of the main transformer.

[0067] The contacts of the first time limit output relay 101a-4a are connected to the branch circuit breaker tripping circuit, which can respond quickly at the early stage of the fault, cut off the fault branch in time, and reduce the scope of the fault impact.

[0068] The contacts of the second time limit output relay 101a-4b are connected to the tripping circuits of the circuit breakers on each side of the main transformer. When the fault worsens or a serious abnormality occurs in the main transformer, the power supply on each side of the main transformer can be cut off in time to prevent the fault from further expanding and ensure the safe and stable operation of the entire standby transformer system.

[0069] The line protection screen 103 is connected to the line protection device 103a, and the line protection device 103a is connected to the failure start circuit of the main protection screen 101 and the auxiliary protection screen 102 through the control cable 103a-1. The control cable 103a-1 includes a voltage switching signal circuit linked to the busbar disconnector to ensure that the line protection device 103a can perform voltage switching according to the status of the busbar disconnector, thereby improving the accuracy and reliability of protection.

[0070] The auxiliary protection screen 102 is connected to the non-electrical protection device 102a, which is connected to the transformer body sensor via a shielded cable 102a-1. The heavy gas contact of the shielded cable 102a-1 is connected in series with the outlet relay 102a-1a, and the light gas contact is connected in series with the signal relay 102a-1b.

[0071] This design ensures that when an abnormality occurs in the transformer itself, such as heavy gas action or light gas alarm, the protection system can respond quickly and take corresponding protection measures, effectively improving the accuracy and reliability of protection.

[0072] The current sampling module 201 includes a high-voltage side current transformer 201a and a branch current transformer 201b. The secondary winding of the high-voltage side current transformer 201a is connected to the differential sampling channel of the main protection screen 101 through the first terminal group, and the secondary winding of the branch current transformer 201b is connected to the overcurrent sampling channel of the main protection screen 101 through the third terminal group.

[0073] Specifically, the high-voltage side current transformer 201a is used to collect the current signal on the high-voltage side of the standby transformer, and its secondary winding is connected to the differential sampling channel of the main protection screen 101 through the first terminal group, thereby accurately transmitting the high-voltage side current signal to the main protection screen 101, providing key data support for differential protection.

[0074] Meanwhile, branch current transformer 201b is responsible for collecting branch line current signals. Its secondary winding is connected to the overcurrent sampling channel of main protection screen 101 via a third terminal group, providing accurate current data for the overcurrent protection function of main protection screen 101. This design ensures that main protection screen 101 obtains current information at key locations in real time, effectively improving the response speed and accuracy of the protection system.

[0075] The voltage sampling module 202 includes a bus voltage transformer 202a, and the secondary winding of the bus voltage transformer 202a is connected to the voltage plug-in 202a-1 of the main protection screen 101 and the auxiliary protection screen 102 through the second terminal group.

[0076] Specifically, the bus voltage transformer 202a adopts a transformation ratio of 110kV / 100V, and the A-phase, B-phase, and C-phase voltage signals of its secondary winding are connected to the input end of the voltage plug-in 202a-1 through a control cable, and the N line is connected to the common ground terminal.

[0077] The voltage plug-in 202a-1 includes a voltage switching relay 202a-1a, the coil of which is connected in series with the auxiliary contact of the busbar disconnector 202a-2. The voltage switching relay 202a-1a is used to automatically switch the voltage sampling circuit according to the state of the busbar disconnector 202a-2.

[0078] Taking the 110kV busbar disconnector as an example, when the disconnector is closed, its auxiliary normally open contact closes, forming a current loop of "DC220V positive pole → busbar disconnector auxiliary contact → voltage switching relay coil → DC220V negative pole". After the relay coil is energized, the contact is attracted, switching the voltage sampling circuit to the secondary winding of the 110kV busbar voltage transformer; when the disconnector is opened, the auxiliary contact is opened, the relay coil loses power, the contact is reset, and the sampling circuit switches to the standby state.

[0079] The voltage switching relay 202a-1a is used to automatically switch the voltage sampling circuit according to the status of the busbar disconnector 202a-2, ensuring that the protection device always collects the voltage signal corresponding to the actual operating busbar, and provides accurate voltage data for re-voltage overcurrent protection, zero-sequence protection, etc.

[0080] The rated voltage of the DC power supply circuit 301 is DC220V; the rated voltage of the AC standby circuit 302 is AC220V. The DC power supply circuit 301 and the AC standby circuit 302 are connected in parallel via an anti-reverse diode.

[0081] The DC power supply circuit 301 adopts a rated voltage of DC220V and is connected to the protection screen unit 100 through a first-level circuit breaker branch. During normal operation, the current starts from the positive pole of the DC220V power supply, flows through the circuit breaker into the WFB-802A protection device of the main protection screen 101, the non-electrical protection device of the auxiliary protection screen 102, etc., and then returns to the negative pole of the power supply through the common ground circuit, forming a complete power supply link.

[0082] The rated voltage of the AC backup circuit 302 is AC220V. It is connected in parallel with the DC power supply circuit 301 through the second-stage circuit breaker, and an anti-reverse diode is connected in series between the two. When the DC power supply circuit is operating normally, the anti-reverse diode cuts off the AC power supply to prevent current backflow; if the DC power supply circuit is cut off due to a fault, the AC220V power supply of the AC backup circuit is turned on through the anti-reverse diode, and the current passes through the second-stage circuit breaker, the anti-reverse diode and the DC circuit shunt circuit breaker in sequence to continuously power the protection device, ensuring that the system can still maintain its protection function when the power supply is abnormal.

[0083] The clock synchronization module 400 also includes an optoelectronic conversion adapter 403, which supports IRIG-B code output. The optical fiber connector of the timing transmission link 402 adopts an FC type interface with a transmission wavelength of 1310nm. The optoelectronic conversion adapter 403 and the timing interface of the protection screen unit 100 are centrally connected through an optical cable terminal box.

[0084] Specifically, the optoelectronic conversion adapter 403 supports IRIG-B code output and is used to convert the electrical signals from the satellite receiver 401 into optical signals. The optical fiber connector of the timing transmission link 402 uses an FC interface with a transmission wavelength of 1310 nm, ensuring stable transmission of the optical signal within the fiber. The optoelectronic conversion adapter 403 and the timing interface of the protection screen unit 100 are centrally connected via a fiber optic cable terminal box. This cable terminal box features a ZOH1X4-FC four-head structure, enabling centralized access and distribution of multiple optical fibers.

[0085] During operation, the satellite receiver 401 receives satellite signals and converts them into electrical signals, which are then fed into the optoelectronic converter adapter 403. The adapter converts the electrical signals into optical signals conforming to the IRIG-B code format, which are then connected to the timing transmission link 402 via FC fiber optic connectors. After distribution through the optical cable terminal box, the optical signals are transmitted to the timing interfaces of the main protection panel 101, auxiliary protection panel 102, and other protection panel units, achieving clock synchronization for each protection device. This design ensures that the clock synchronization accuracy meets relay protection requirements and guarantees the consistency and accuracy of the operating times of each device.

[0086] The main protection screen 101, auxiliary protection screen 102 and line protection screen 103 of the protection screen unit 100 form a failure start loop network through the control cable 103a-1. Any action of the protection screen can trigger the failure protection function of other protection screens.

[0087] The protection devices in the main protection screen 101, the non-electrical protection devices of the auxiliary protection screen 102 and the line protection devices of the line protection screen 103 are hard-wired to each other through control cables.

[0088] When main protection panel 101 detects a fault and trips, the failure-initiating contacts of its output relay assembly close, transmitting current via control cables to the failure-initiating circuits of auxiliary protection panel 102 and line protection panel 103, triggering the failure protection functions of the other protection panels. Similarly, when the non-electrical protection function of auxiliary protection panel 102 or the line protection function of line protection panel 103 is activated, its failure-initiating contacts send a start signal to the other two protection panels via control cables, forming a failure protection mechanism in which "any panel's action triggers the entire network."

[0089] Example 3

[0090] Reference Figures 1 to 25 , which is the third embodiment of the present invention. This embodiment is different from the second embodiment in that: first, during normal operation, the DC power supply circuit 301 of the power and synchronization unit 300 provides a stable DC220V voltage to the main protection screen 101, the auxiliary protection screen 102 and the line protection screen 103.

[0091] The current starts from the DC power supply and flows to each protection screen through the first-level circuit breaker branch to provide working power for the protection device in the screen. Among them, the DC power supply circuit 301 adopts a high-performance DC power supply module whose model is DCF220V-100A. This module has high conversion efficiency and stable output characteristics, and can ensure that a reliable and stable DC220V voltage is provided for the main protection screen 101, auxiliary protection screen 102 and line protection screen 103 under various working conditions.

[0092] The AC backup circuit 302 preferably adopts the ACB220V-80A model, which has good voltage stabilization performance and anti-interference ability, and can be quickly put into use when an abnormality occurs in the DC power supply circuit 301 to ensure uninterrupted power supply to the system.

[0093] This dual power supply mode effectively avoids the risk of power loss to the protection system due to a single power supply failure, significantly improves power supply reliability, and provides a solid foundation for the stable operation of the substation.

[0094] Furthermore, the current sampling module 201 and the voltage sampling module 202 of the sampling unit 200 collect current and voltage signals in real time and transmit them to the protection screen unit 100. The current is induced in the high-voltage side current transformer 201a and the branch current transformer 201b, and after being converted according to a certain ratio, it flows to the differential sampling channel and overcurrent sampling channel of the main protection screen 101 through the first terminal group and the third terminal group.

[0095] Among them, the high-voltage side current transformer 201a preferably adopts the CT-HV-500A model, which has the characteristics of high precision and high stability, and can accurately convert the large current on the high-voltage side into a secondary current suitable for use by the protection device.

[0096] The branch current transformer 201b preferably adopts the CT-BR-200A model, which also has high precision and good linearity, and can accurately reflect the current changes of the branch line. At the same time, the bus voltage transformer 202a preferably adopts the VT-MB-10kV model, which converts the high voltage on the bus into a low voltage signal in proportion, and transmits it to the voltage plug-in 202a-1 of the main protection screen 101 and the auxiliary protection screen 102 through the second terminal group.

[0097] The voltage transformer has good insulation performance and high-precision conversion characteristics, which can ensure the accuracy and reliability of voltage sampling. These high-precision sampling devices can accurately reflect the operating status of the power grid, provide reliable data support for the accurate operation of the protection device, effectively avoid false operation or refusal to operate due to sampling errors, and greatly improve the reliability and accuracy of the protection system.

[0098] Furthermore, the main protection device 101a in the main protection panel 101 calculates and judges differential protection, re-voltage overcurrent protection and zero-sequence protection based on the received current and voltage signals. The current flows between the various protection units inside the main protection device 101a, providing a basis for the protection action.

[0099] The main protection device 101a preferably adopts the MPA-MP-3000 model, which has powerful data processing capabilities and fast protection action capabilities. The differential protection unit 101a-1, re-pressure overcurrent protection unit 101a-2 and zero-sequence protection unit 101a-3 inside the main protection device 101a all adopt advanced algorithms and hardware designs, and can accurately identify and judge various fault types.

[0100] For example, the differential protection unit 101a-1 receives the current signal from the high-voltage side current transformer 201a and compares it with the current during normal operation to determine whether a short-circuit fault exists. If a fault is detected, the differential protection unit 101a-1 issues a trip command. Current flows from the output relay assembly 101a-4 of the protection panel through the trip circuit to the branch circuit breaker or the circuit breakers on each side of the main transformer, causing them to trip and disconnect the faulty part. This fast-response protection mechanism isolates the fault promptly, minimizing the impact of the fault on equipment and the power grid, and effectively ensuring the safe operation of the substation.

[0101] Furthermore, the clock synchronization module 400 receives the precise time signal through the satellite receiving device 401 and transmits the time signal to the protection screen unit 100 to achieve time synchronization of each device. The current flows in the circuit inside the clock synchronization module 400 to ensure the accurate transmission of the time signal.

[0102] The satellite receiving device 401 preferably adopts a high-precision GPS satellite receiver whose model is SR-GPS-9000. The satellite receiving device 401 can receive signals from multiple satellites to ensure the accuracy and reliability of the time signal.

[0103] The photoelectric conversion adapter 403 preferably uses a high-performance photoelectric converter, model PT-FC-1310, which supports IRIG-B code output to ensure the accuracy and versatility of the time signal. The time transmission link 402 uses an optical fiber connection, and its optical fiber connector uses an FC type interface with a transmission wavelength of 1310nm. It has the advantages of long transmission distance and strong anti-interference ability, ensuring the stability and reliability of the time signal during transmission.

[0104] This high-precision time synchronization function helps to accurately analyze the chronological order of fault occurrence, provides strong support for fault diagnosis and accident handling, and greatly improves the efficiency and accuracy of substation operation management.

[0105] The output end of the timing transmission link 402 is connected to the timing interface of the protection screen unit 100, and is centrally connected through the optical cable terminal box to achieve time synchronization of each device in the protection screen unit 100. Each device in the protection screen unit 100 is calibrated and synchronized according to the received precise time signal to ensure the time consistency of the entire standby transformer protection system, and provide an accurate time reference for functions such as fault recording and event sequence recording.

[0106] When a short circuit fault occurs on the high-voltage side of the standby transformer, the high-voltage side current transformer 201a in the current sampling module 201 collects the fault current signal, the current increases sharply, and is transmitted to the differential protection unit 101a-1 of the main protection screen 101 through the first terminal group.

[0107] Furthermore, after differential protection unit 101a-1 detects a short-circuit fault, the contacts of first-time output relay 101a-4a in output relay assembly 101a-4 close, allowing current to flow through the relay contacts, connecting the branch circuit breaker trip circuit, tripping the branch circuit breaker and isolating the faulty branch. If the fault is severe and persistent, the contacts of second-time output relay 101a-4b close, causing current to flow through the circuit breaker trip circuits on each side of the main transformer, tripping the circuit breakers on each side of the main transformer and further isolating the fault.

[0108] At the same time, after the line protection screen 103 receives the tripping instruction from the main protection screen 101 through the optical communication link, it controls the circuit breaker of the corresponding line to trip, cuts off the faulty line, and the current flows from the control circuit of the line protection screen 103 to the tripping circuit of the line circuit breaker, thereby protecting the line.

[0109] When an abnormality or failure occurs in the main protection panel 101, the auxiliary protection panel 102 is put into operation in time through the non-electrical protection device 102a to control the tripping of the high-voltage side circuit breaker to ensure the safe and stable operation of the system. At this time, the current flows from the non-electrical protection device 102a of the auxiliary protection panel 102 to the tripping circuit of the high-voltage side circuit breaker to complete the isolation of the fault.

[0110] This comprehensive protection coordination mechanism ensures that the protection system can operate quickly and accurately under various fault conditions, preventing the fault from expanding and effectively protecting the safety of substation equipment and power grids.

[0111] Furthermore, the line protection screen 103 is connected to the line protection device 103a, and is connected to the failure start circuit of the main protection screen 101 and the auxiliary protection screen 102 through the control cable 103a-1, so as to protect the line of the standby transformer power supply.

[0112] The line protection device 103a is connected to the failure start circuit of the main protection screen 101 and the auxiliary protection screen 102 through the control cable 103a-1. When a line fault occurs, the line protection device 103a receives the tripping command from the main protection screen 101 through the optical communication link, controls the circuit breaker of the corresponding line to trip, and cuts off the faulty line.

[0113] Control cable 103a-1 includes a voltage switching signal circuit linked to the busbar disconnector, ensuring that line protection device 103a can switch voltages based on the busbar disconnector's status, improving protection accuracy and reliability. Line protection device 103a preferably uses the LPA-LP-2000 model, which features fast action and high reliability. It effectively protects lines from fault damage, promptly disconnects faulty lines, minimizes the impact of faults on the grid, and ensures continuity and reliability of power supply.

[0114] In summary, the standby transformer protection system ensures the safe and stable operation of the substation through the close collaboration of various modules. The protection screen unit 100 realizes comprehensive protection of the standby transformer, the sampling unit 200 provides accurate current and voltage signals, the power and synchronization unit 300 ensures stable power supply, and the clock synchronization module 400 realizes time synchronization of the system.

[0115] When a fault occurs, the system can quickly and accurately remove the faulty part, minimizing the impact on production. The high-performance components used in each module further improve the system's reliability, accuracy, and speed, providing a strong guarantee for the safe operation of the substation.

[0116] Finally, it should be pointed out that the methods and devices described in detail above are merely embodiments, and those skilled in the art can modify these embodiments in different ways without departing from the scope of the present invention.

Claims

1. A standby transformer protection system, characterized by: include, Protect The screen unit (100) comprises a main protection screen (101), an auxiliary protection screen (102) and a line protection screen (103), wherein the main protection screen (101) and the auxiliary protection screen (102) are connected to two sets of trip coils of a high-voltage side circuit breaker via a trip circuit, and the line protection screen (103) establishes a communication connection with the main protection screen (101) via an optical communication link; The sampling unit (200) comprises a current sampling module (201) and a voltage sampling module (202), wherein the current sampling module (201) is connected to the differential protection plug-in of the main protection screen (101) through a first terminal group, and the voltage sampling module (202) is connected to the voltage plug-ins of the main protection screen (101) and the auxiliary protection screen (102) through a second terminal group. The power and synchronization unit (300) comprises a DC power supply circuit (301) and an AC backup circuit (302), wherein the DC power supply circuit (301) is connected to the protection screen unit (100) via a first-stage circuit breaker branch, and the AC backup circuit (302) is connected in parallel to the DC power supply circuit (301) via a second-stage circuit breaker. The clock synchronization module (400) comprises a satellite receiving device (401) and a time synchronization transmission link (402), wherein the satellite receiving device (401) is connected to the time synchronization interface of the protection screen unit (100) via a photoelectric conversion adapter, and the input end of the time synchronization transmission link (402) is connected to the photoelectric conversion adapter, and the output end is connected to the time synchronization interface of the protection screen unit (100).

2. The starting and standby transformer protection system according to claim 1, characterized in that: The main protection screen (101) and the auxiliary protection screen (102) are both connected to a main protection device (101a), and the main protection device (101a) comprises a differential protection unit (101a-1), a re-pressure overcurrent protection unit (101a-2), and a zero-sequence protection unit (101a-3); The differential protection unit (101a-1) is connected to the high-voltage side current signal of the current sampling module (201) through the first terminal group, and the re-voltage overcurrent protection unit (101a-2) and the zero-sequence protection unit (101a-3) are connected to the bus voltage signal of the voltage sampling module (202) through the second terminal group.

3. The starting and standby transformer protection system according to claim 2, characterized in that: The outlet relay assembly (101a-4) of the main protection device (101a) comprises a first time limit outlet relay (101a-4a) and a second time limit outlet relay (101a-4b); The contacts of the first time-limited output relay (101a-4a) are connected to the tripping circuit of the branch circuit breaker, and the contacts of the second time-limited output relay (101a-4b) are connected to the tripping circuits of the circuit breakers on each side of the main transformer.

4. The starting and standby transformer protection system according to claim 2 or 3, characterized in that: The line protection screen (103) is connected to a line protection device (103a), and the line protection device (103a) is connected to the failure start circuit of the main protection screen (101) and the auxiliary protection screen (102) via a control cable (103a-1). The control cable (103a-1) includes a voltage switching signal circuit linked to a busbar disconnector.

5. The starting and standby transformer protection system according to claim 4, characterized in that: The auxiliary protection screen (102) is connected to a non-electrical quantity protection device (102a), and the non-electrical quantity protection device (102a) is connected to a transformer body sensor via a shielded cable (102a-1). The heavy gas contact of the shielded cable (102a-1) is connected in series with an outlet relay (102a-1a), and the light gas contact is connected in series with a signal relay (102a-1b).

6. The starting and standby transformer protection system according to claim 5, characterized in that: The current sampling module (201) comprises a high-voltage side current transformer (201a) and a branch current transformer (201b); the secondary winding of the high-voltage side current transformer (201a) is connected to the differential sampling channel of the main protection screen (101) through a first terminal group; and the secondary winding of the branch current transformer (201b) is connected to the overcurrent sampling channel of the main protection screen (101) through a third terminal group.

7. The starting and standby transformer protection system according to claim 5 or 6, characterized in that: The voltage sampling module (202) comprises a bus voltage transformer (202a), and the secondary winding of the bus voltage transformer (202a) is connected to the voltage plug-in (202a-1) of the main protection screen (101) and the auxiliary protection screen (102) through a second terminal group; The voltage plug-in (202a-1) comprises a voltage switching relay (202a-1a), the coil of the voltage switching relay (202a-1a) being connected in series with the auxiliary contact of the busbar isolating switch (202a-2), and the voltage switching relay (202a-1a) being used to automatically switch the voltage sampling circuit according to the state of the busbar isolating switch (202a-2).

8. The starting and standby transformer protection system according to claim 7, characterized in that: The rated voltage of the DC power supply circuit (301) is DC220V; the rated voltage of the AC standby circuit (302) is AC220V, and the DC power supply circuit (301) and the AC standby circuit (302) are connected in parallel via an anti-reverse diode.

9. The starting and standby transformer protection system according to claim 8, characterized in that: The clock synchronization module (400) further comprises a photoelectric conversion adapter (403), wherein the photoelectric conversion adapter (403) supports IRIG-B code output, the optical fiber connector of the timing transmission link (402) adopts an FC type interface, and the transmission wavelength is 1310 nm, and the photoelectric conversion adapter (403) and the timing interface of the protection screen unit (100) are centrally connected via an optical cable terminal box.

10. The starting and standby transformer protection system according to claim 9, characterized in that: The main protection screen (101), the auxiliary protection screen (102) and the line protection screen (103) of the protection screen unit (100) form a failure start loop network through a control cable (103a-1), and any action of the protection screen can trigger the failure protection function of other protection screens.

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