Bus differential protection capacity expansion method and system and storage medium

Abstract

The invention discloses a busbar differential protection capacity expansion method and system and a storage medium, and belongs to the technical field of power system relay protection. The method is applied to a double-bus wiring system configured with two sets of redundant bus differential protection devices, and the core is a differential transformation scheme: firstly analyzing hardware configuration and branch distribution conditions of the two sets of devices, directly adding a branch to a device with spare resources, and accessing a newly-added main transformer interval; and for the device with the full branches, the access position is vacated by adjusting the branch distribution of the existing incoming line interval and the main transformer interval. In the construction process, short circuit is carried out first and then reconnection is carried out to guarantee the safety of a current loop, and hardware wiring optimization, protection program upgrading and function verification are matched to complete transformation. The corresponding system comprises the bus differential protection device transformed by the method, and a computer readable storage medium for storing a program upgrading step. The whole set of equipment does not need to be replaced, the existing hardware redundancy expansion function is utilized, the modification cost is low, the safety risk is small, and the flexibility is high.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of power system relay protection technology, and in particular to a bus differential protection capacity expansion method and system and a storage medium. BACKGROUND

[0002] In 220kV substations of large industrial enterprises and regional power grids, the double busbar connection mode is widely used due to its flexible operation and high reliability. In order to improve the reliability of the protection system, two sets of bus differential protection devices that are completely independent in function and redundant to each other are usually configured in such substations. The hardware design of each set of bus differential protection devices has a fixed input / output capacity limit, i.e., it can only connect to a specified number of current, voltage and switching quantity signals of electrical intervals (such as incoming lines, bus couplers and main transformers).

[0003] As the production scale of enterprises expands or the load of power grids increases, substations often need to be expanded and new main transformers are added. At this time, the newly added main transformer interval needs to be included in the bus differential protection range. If the branch resources in the original bus differential protection device used to connect the main transformer interval have reached the design upper limit, it will face the problem of expansion. There are mainly two traditional solutions: one is to replace the protection screen cabinet and device as a whole, and the other is to uniformly add hardware expansion modules for all devices.

[0004] However, the overall replacement scheme is costly, with huge costs of purchasing new equipment and construction, and a long construction period, which requires the key protection to be out of operation for a long time, posing a great risk to the safety and stability of the power grid. The scheme of uniformly adding hardware modules avoids the overall replacement, but does not fully consider the differences in the actual resource configuration of the two sets of redundant devices, which may lead to the waste phenomenon that one set of device resources is idle while the other set still needs to be expanded, and there are major safety risks such as opening the secondary side of the current transformer during live circuit modification. SUMMARY

[0005] The present application aims to overcome the defects of high cost, high safety risk and insufficient utilization of device redundancy in the prior art bus differential protection modification, and provides a bus differential protection capacity expansion method, system and storage medium, which "tailors" the modification strategy for the two sets of redundant protection devices through fine differential analysis, fully utilizes the existing redundant resources of the system, and realizes the connection of the newly added main transformer interval with the lowest hardware modification and the highest safety standard.

[0006] To achieve the above-mentioned purpose, the present application adopts the following technical solutions: In a first aspect, the present application provides a bus differential protection capacity expansion method applied to a double busbar connection system configured with a first set of bus differential protection devices and a second set of bus differential protection devices that are redundant to each other. The method comprises the following steps: S1: Analyze the hardware configuration of the first set of bus differential protection devices and the second set of bus differential protection devices, and determine the total number of branches that can be accessed by each device and the current branch allocation status.

[0007] S2: Based on the analysis results of step S1, formulate differentiated transformation plans: For one set of bus differential protection devices with spare hardware resources, plan to connect to the new main transformer bay by adding a new branch; for another set of bus differential protection devices whose branches are full, plan to adjust its existing branch allocation to free up access positions for connecting to the new main transformer bay.

[0008] S3: Based on the differentiated transformation plan, perform the corresponding branch adjustments and hardware wiring modifications.

[0009] S4: Upgrade the protection program for the bus differential protection device after hardware modification to adapt to the new branch configuration.

[0010] S5: Perform functional verification on the upgraded bus differential protection device to ensure that the newly added main transformer bay is correctly included in the bus differential protection range.

[0011] Further, in step S2, the step of freeing up access positions by adjusting the existing branch allocation includes: re-allocating branches already allocated to one or more first-class bays in the bus differential protection device whose branches are full to the newly added main transformer bay; simultaneously, migrating the one or more first-class bays to other vacant branches in the device or re-allocating them to branches in other second-class bays. The first-class bays and second-class bays can be different types such as incoming line bays and outgoing line bays.

[0012] Furthermore, in step S3, for the bus differential protection device involving branch adjustment, the hardware wiring modification adopts the following construction method: First, short-circuit the current loop corresponding to the branch to be relocated on the outside of the terminal block of the bus differential protection device; then disconnect the original wiring from the inside of the terminal block to the protection device interface and reconnect it to the device interface corresponding to the target branch. This method effectively prevents the secondary side of the current transformer from opening during the rewiring process.

[0013] Furthermore, when short-circuiting outside the terminal block, the current carrying capacity of the shorting piece used shall not be less than 1.2 times the current carrying capacity of the original current loop conductor, and the short-circuiting operation shall be performed after the relevant secondary protection measures of the current transformer are put into operation to ensure operational safety.

[0014] Furthermore, in step S3, the hardware wiring modification also includes: synchronously rewiring the main transformer failure release voltage blocking circuit and the switch auxiliary contact position input circuit associated with the adjusted branch according to the new branch allocation relationship, and ensuring that the wiring identification corresponds to the new branch number to ensure that the signals correspond one-to-one.

[0015] Furthermore, in step S3, for the bus differential protection device modified by adding a new branch, the hardware wiring modification includes: adding a corresponding terminal block and an outlet pressure plate to construct the new branch; the current sampling circuit of the new branch is connected by a shielded cable, and the shielding layer of the shielded cable is grounded at one end to suppress electromagnetic interference.

[0016] Further, in step S4, the protection program upgrade includes: updating the branch configuration parameters and bay type definition in the bus differential protection device; updating the protection logic program so that it can correctly process electrical quantity information and switching quantity information from the newly added branch or the adjusted branch; after the program upgrade, performing a three-remote test including telemetry, remote signaling and remote control functions for preliminary verification.

[0017] Furthermore, the method also includes step S6: after the functional verification in step S5 is passed, the newly added main transformer interval is subjected to a load test to monitor its current phase, amplitude and protection action behavior, so as to finally confirm the correctness of the protection function in the operating state.

[0018] Secondly, this invention provides a 220kV substation bus differential protection system applied to a double busbar connection system. The system includes at least one bus differential protection device, which is an upgraded device modified using the method described above, enabling it to protect more main transformer bays than originally designed.

[0019] Thirdly, the present invention provides a computer-readable storage medium having a computer program stored thereon. When the computer program is executed by a processor, it implements the protection program upgrade step S4 in the method described above.

[0020] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are: 1. Excellent economic efficiency: By making full use of existing redundant hardware resources and implementing a differentiated strategy to achieve "one addition and one adjustment", the replacement of the entire protection device or blind hardware addition is avoided, which greatly saves the transformation cost.

[0021] 2. Extremely high safety: The proposed standardized construction process of "short-circuiting first, then reconnecting" fundamentally eliminates the risk of open circuit in the secondary circuit of the current transformer, and makes strict provisions on the specifications of the short-circuit piece and the operating conditions, ensuring the safety of the construction process and the operating equipment.

[0022] 3. Short construction period and minimal impact: The renovation plan is highly targeted and the construction scope is precise. It does not require large-scale disconnection and wiring, which significantly shortens the time when the protection device may be out of operation and minimizes the impact on the normal operation of the power grid.

[0023] 4. High flexibility and versatility: The core idea of ​​this method—differentiated transformation based on resource configuration analysis—can be extended to various protection system expansion scenarios with redundant configurations, and is not limited to specific equipment models or 220kV voltage levels, making it widely applicable.

[0024] 5. Complete and reliable functions: The upgrade covers the entire chain of adaptation from hardware wiring and software parameters to protection logic, and ensures the completeness and reliability of the protection functions of the newly added bays through multi-level verification from static testing to dynamic testing under load. Attached Figure Description

[0025] Figure 1 This is a flowchart illustrating the overall process of the method of the present invention. Figure 2 This is a schematic diagram of the wiring principle for modifying a bus differential protection device with spare resources by adding a new branch, as shown in this embodiment of the invention. Figure 3 This is a schematic diagram of the wiring principle and safe construction process for modifying a bus differential protection device with a full branch using a branch adjustment method, as described in this embodiment of the invention. Figure 4 A schematic diagram of the structure of a 220kV substation bus differential protection system after being upgraded using the method described in this embodiment of the invention. Detailed Implementation

[0026] To enable those skilled in the art to better understand the technical solution of the present invention, the present invention will be described in detail below. The description in this part is only exemplary and explanatory, and should not be used to limit the scope of protection of the present invention in any way.

[0027] Example 1: Application of the Method This embodiment uses the renovation project of a 220kV substation of a company in Hunan Province as the application scenario. The substation adopts a double busbar connection and is equipped with two sets of redundant bus differential protection devices: the first set of bus differential protection devices is the SGB-750A-G type bus differential protection panel I, and the second set of bus differential protection devices is the PCS-915A-G-1A-G9 type bus differential protection panel II. Due to the increase in the company's power load, a new 180MVA No. 7 main transformer needs to be added. The existing bus differential protection devices have reached the saturation of the main transformer bays (each device was originally designed to connect a maximum of 4 main transformer bays). The method of this invention is needed to connect the new main transformer bay.

[0028] Step S1: Hardware Configuration Analysis A comprehensive survey was conducted on the hardware configuration and branch allocation of the two bus differential protection devices. The specific results are as follows: like Figure 2As shown, the first set of bus differential protection device (SGB-750A-G) (with spare resources): can connect a total of 20 branches. The current allocation is 4 220kV incoming line bays, 1 bus tie bay, and 4 main transformer bays. The remaining 11 branches are not in use, and it has the hardware redundancy to connect to the newly added main transformer bay. like Figure 3 As shown, the second set of bus differential protection devices (PCS-915A-G-1A-G9) (main transformer branch is full): the total number of branches that can be connected is 16. The current allocation is 4 220kV incoming line bays (branch 4-6 and branch 10), 1 bus tie bay (branch 7), and 4 main transformer bays (branch 1-3 and branch 8). The main transformer branches are saturated and there are no directly usable spare main transformer branches.

[0029] Step S2: Differentiated Modification Plan Development Based on the analysis results of Step S1, differentiated modification plans are developed for the two sets of equipment: 1. First bus differential protection device upgrade plan: Utilize its spare hardware resources, add branch 19 as the access branch of the No. 7 main transformer bay. There is no need to adjust the existing branch allocation, only the corresponding terminal blocks, pressure plates and wiring need to be added. 2. Second bus differential protection device modification scheme: adopt the branch adjustment strategy, reassign the original branches 4-6 allocated to the three incoming line bays A, B, and C to the main transformer bay #7, and at the same time relocate the incoming line bays A, B, and C to branches 8-10 (the original branch 8 is a spare bay, and branches 9-10 are reassignable branches), freeing up branch 4 as the access position for the main transformer bay #7.

[0030] Step S3: Branch circuit adjustment and hardware wiring modification. Hardware modifications will be performed on two sets of devices according to the modification plan. Specific construction details are as follows: 1. Construction of the first set of bus differential protection devices: (1) Add terminal block 1CLP19 and trip pressure plate ISLP5 to the bus differential protection I panel. The terminal block model is matched with the interface specification of the SGB-750A-G device. (2) A copper core shielded cable with a cross-sectional area of ​​4 mm² is used to connect the secondary side of the current transformer in the No. 7 main transformer bay to the current sampling circuit of the newly added branch 19. The cable shield is grounded at one end on the device side. (3) Complete the wiring of the main transformer failure release voltage lockout circuit and the knife switch position input circuit, and connect the relevant signal lines to the corresponding interfaces of the newly added terminal blocks to ensure that the wiring numbers correspond one-to-one with the numbers of branch 19.

[0031] 2. Construction of the second set of bus differential protection devices (core safety construction process): (1) Preparation before construction: Put on the open circuit protection device on the secondary side of the current transformer and prepare a copper shorting piece with a current carrying capacity of 300A (the current carrying capacity of the original incoming line bay current line is 250A, and the current carrying capacity of the shorting piece is 1.2 times the original current carrying capacity). (2) Short-circuiting current lines: On the outside of the terminal block of the bus differential protection II panel, short-circuit the current lines 4-6 of the corresponding branches of the A, B, and C incoming line intervals with shorting pieces to ensure the continuity of the current loop and avoid open circuit; (3) Wiring connection: Disconnect the wiring of branch 4-6 from the inside of the terminal block to the protection device, and connect it to the device interface corresponding to branch 8-10; at the same time, connect the current line, voltage blocking line and disconnector position line of the main transformer bay #7 to the terminal block and device interface of branch 4. (4) External cable modification: The external cables of the A, B, and C incoming line intervals are moved from the branch 4-6 terminal block to the branch 8-10 terminal block. The external cable of the No. 7 main transformer is connected to the branch 4 terminal block. All cable joints are fixed with crimp terminals and insulated.

[0032] Step S4: Protection Program Upgrade. Contact the technical personnel of the bus differential protection device manufacturer to upgrade the programs of both devices. Specific details include: The first set of devices (SGB-750A-G): Add configuration parameters for branch 19 to the protection program, define the bay type as "main transformer bay", enter the rated current, transformation ratio and other parameters of the No. 7 main transformer, and update the bus differential protection logic to include the electrical quantity judgment of branch 19. The second set of equipment (PCS-915A-G-1A-G9): Modify the bay type definition of branches 4-6 and 8-10, change branch 4 to "main transformer bay" and branch 8-10 to "incoming line bay", update the correspondence between bay number and branch to ensure that the protection logic adapts to the new branch allocation. Program verification: After the upgrade is completed, a three-remote test is performed. Remote control commands are sent through the background monitoring system to verify that the telemetry, remote signaling and remote control functions of branch 19 and branch 4 are normal and that the protection device can correctly receive and process relevant signals.

[0033] Step S5: Functional Verification like Figure 1 As shown, the protection function is verified by combining simulated fault testing and load testing: Simulated fault test: The simulated fault current of the No. 7 main transformer bay was injected into the two sets of bus differential protection devices through the relay protection tester to verify that the bus differential protection devices can correctly identify the fault section and accurately send the trip command to the circuit breaker of the No. 7 main transformer. Switching test: Perform double busbar switching operation to verify the selectivity and speed of the bus differential protection during the busbar switching process of the No. 7 main transformer bay, and ensure that there are no protection maloperations or failures to operate; 3. Load test (step S6): After the No. 7 main transformer is put into operation, check that the current distribution of branch 19 and branch 4 is uniform, the voltage matching error is less than 2%, and the protection action response time is controlled within 50ms, which meets the requirements of the "Power System Relay Protection Regulations".

[0034] Example 2: 220kV Substation Bus Differential Protection System like Figure 4 As shown, this embodiment provides a 220kV substation bus differential protection system modified using the method of Embodiment 1. The system includes: The first set of bus differential protection device (SGB-750A-G): After modification, it is connected to 5 main transformer bays (including the newly added 7# main transformer branch 19), retains 4 incoming line bays and 1 bus tie bay, and the protection range covers the double busbars and all main transformer and incoming line bays. The second set of bus differential protection devices (PCS-915A-G-1A-G9): After modification, it connects to 5 main transformer bays (including the newly added 7# main transformer branch 4), retains 4 incoming line bays (moved to branch 8-10 and the original branch 10), and 1 bus tie bay, forming a redundant backup with the first set of devices. The background monitoring system collects the operating status and branch electrical quantity data of the two sets of bus differential protection devices in real time, and supports protection setting modification, fault record query and remote control functions. Primary equipment layer: including busbars, circuit breakers, disconnect switches, and current / voltage transformers in each bay, providing raw electrical information for protection devices.

[0035] After being modified using the method in Example 1, the system expands its protection capacity without replacing the core protection equipment, forming dual protection for the newly added main transformer bay and improving the overall operational reliability of the substation.

[0036] Example 3: Computer-readable storage medium This embodiment provides a computer-readable storage medium (such as a USB flash drive, optical disc, or solid-state drive) storing dedicated software tools for upgrading the differential protection device program. The software includes: Configuration parsing module: used to read the device's current configuration file and allow engineers to input new branch-interval mapping relationships.

[0037] Parameter and logic generation module: Based on the new mapping relationship, automatically generate or modify the setpoint parameters, interval attribute configurations and differential protection logic judgment code blocks required for device operation.

[0038] Communication and testing module: Supports downloading upgrade programs through device communication interfaces (such as Ethernet and serial ports), and can automatically execute basic remote control test scripts and provide feedback on upgrade results.

[0039] When the program in the storage medium is run by an engineer on a workstation, it can efficiently and systematically complete the protection program upgrade task described in step S4 of the aforementioned method, reducing human error and improving the efficiency of the transformation.

[0040] This article uses specific examples to illustrate the principles and implementation methods of the present invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of the present invention. The above are merely preferred embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the technical scope disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be within the scope of protection of the present invention.

Claims

1. A method for expanding the capacity of bus differential protection, applied to a dual-busbar connection system equipped with a first set of redundant bus differential protection devices and a second set of redundant bus differential protection devices, characterized in that, The method includes: S1: Analyze the hardware configuration of the first set of bus differential protection devices and the second set of bus differential protection devices to determine the total number of branches that can be accessed by each device and the current branch allocation status; S2: Based on the analysis results of step S1, formulate differentiated transformation plans: For one set of bus differential protection devices with spare hardware resources, plan to connect to the new main transformer bay by adding a new branch; for another set of bus differential protection devices with full branches, plan to adjust its existing branch allocation to free up access positions for connecting to the new main transformer bay. S3: Based on the aforementioned differentiated modification plan, perform the corresponding branch adjustments and hardware wiring modifications; S4: Upgrade the protection program for the bus differential protection device after hardware modification to adapt to the new branch configuration; S5: Perform functional verification on the upgraded bus differential protection device to ensure that the newly added main transformer bay is correctly included in the bus differential protection range.

2. The bus differential protection capacity expansion method according to claim 1, characterized in that, In step S2, the step of adjusting the existing branch allocation to free up access positions includes: In the bus differential protection device where the branch is full, the branches that have been allocated to one or more Class I bays will be reassigned to the newly added main transformer bay; Simultaneously, the one or more first-class intervals are migrated to other idle branches in the device or reassigned to branches of other second-class intervals.

3. The bus differential protection capacity expansion method according to claim 2, characterized in that, In step S3, for the bus differential protection device involving branch line adjustment, the hardware wiring modification adopts the following construction method: First, short-circuit the current loop corresponding to the branch to be relocated outside the terminal block of the bus differential protection device; Then disconnect the original wiring from the inside of the terminal block to the protection device interface and reconnect it to the device interface corresponding to the target branch.

4. The bus differential protection capacity expansion method according to claim 3, characterized in that, When short-circuiting outside the terminal block, the current carrying capacity of the shorting piece used shall not be less than 1.2 times the current carrying capacity of the original current loop conductor, and the short-circuiting operation shall be performed after the relevant secondary protection measures of the current transformer are put into operation.

5. The bus differential protection capacity expansion method according to claim 2 or 3, characterized in that, In step S3, the hardware wiring modification also includes: synchronously rewiring the main transformer failure release voltage blocking circuit and the switch auxiliary contact position opening circuit associated with the adjusted branch according to the new branch allocation relationship, and making the wiring identification consistent with the new branch number.

6. The bus differential protection capacity expansion method according to claim 1, characterized in that, In step S3, for the bus differential protection device that is modified by adding a new branch, the hardware wiring modification includes: adding a corresponding terminal block and an outlet pressure plate to construct the new branch; the current sampling circuit of the new branch is connected by a shielded cable, and the shielding layer of the shielded cable is grounded at one end.

7. The bus differential protection capacity expansion method according to claim 1, characterized in that, In step S4, the protection program upgrade includes: Update the branch configuration parameters and bay type definitions within the bus differential protection device; Update the protection logic program so that it can correctly process electrical quantity information and switch quantity information from newly added or adjusted branches; After the program is upgraded, a three-remote test, including telemetry, remote signaling, and remote control functions, will be conducted for preliminary verification.

8. The bus differential protection capacity expansion method according to claim 1, characterized in that, The method further includes step S6: after the function verification in step S5 is passed, the newly added main transformer interval is subjected to load test to monitor its current phase, amplitude and protection action behavior, so as to finally confirm the correctness of the protection function in the operating state.

9. A 220kV substation bus differential protection system, applied to a double busbar connection system, characterized in that, It includes at least one bus differential protection device, which is an upgraded device using the method described in any one of claims 1 to 8, so that the device can protect more main transformer bays than its original design number.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by the processor, it implements the protection program upgrade step S4 in the method as described in any one of claims 1 to 8.

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