A medium-voltage distribution network maintenance sequence control method and system

Abstract

The application discloses a kind of medium voltage distribution network maintenance sequence control method and system, belong to medium voltage distribution network maintenance technical field.The application will be developed into intermediate topology state sequence for each maintenance operation ticket;Interval short-circuit calculation is carried out to each state, and the upper and lower limits of fault current flowing through each protection device are obtained;Based on the upper and lower limits of fault current, the hard margin set containing sensitivity margin, selectivity margin, load separation margin, direction element margin and ground distinguishable margin is calculated;The minimum value of hard margin is taken as the operation barrier value, and the protection distinguishability certificate containing protection setting value group and pre-allowed set is generated;Before field operation, the setting value group must be read back consistent with the certificate, the measured electrical quantity is in the pre-allowed set, and the barrier value is non-negative before releasing the operation permission;When the certificate fails, repair and recalculate all certificates.The application can identify the mismatch risk of intermediate state protection in operation, and realize item-by-item hard interlocking control.

Description

Technical Field

[0001] This invention belongs to the field of uninterrupted power supply maintenance technology for medium-voltage distribution networks, specifically relating to a sequence control method and system for uninterrupted power supply maintenance of medium-voltage distribution networks. Background Technology

[0002] Live-line maintenance (LCOE) of medium-voltage distribution networks is an important means to improve power supply reliability and reduce power outage time for users. It typically involves multiple operational steps, including paralleling mobile generators, closing tie switches, disconnecting switches on both sides of the maintenance section, islanding, and restoring the original power supply path after maintenance. With the large-scale integration of distributed photovoltaic systems and the widespread use of mobile power sources, the characteristics of fault currents during maintenance have changed significantly: after transitioning from grid-connected to islanded mode, the fault current may drop from thousands of amperes to near the protection activation value; a certain intermediate state during loop closing or opening may also create bidirectional fault currents, causing the original directional overcurrent protection, zero-sequence protection, or main / backup time-delay coordination to fail. The essence of the above problems is that the steady-state power flow in a certain transient intermediate state during operation may still be within the allowable range, but the fault current is too small, causing protection to fail to operate, or bidirectional currents cause mismatch in main / backup protection. These hidden risks cannot be detected through traditional final-state power flow verification.

[0003] To address the aforementioned issues, relevant technical solutions have been proposed: Chinese invention patent CN115085185B discloses a method for selecting a tie switch and implementing uninterrupted power transfer based on the steady-state current of a switch opening and closing. The core idea of ​​this solution is to select the switch with the smallest steady-state current among multiple selectable tie switches for power transfer operations, thereby reducing operational impact. However, this method focuses on the question of "which switch to select," only filtering based on the steady-state current of the switch operation itself, without addressing the issue of whether the protection device can reliably detect and clear faults during operation—even if the selected tie switch has the smallest opening and closing current, there is still a risk that the fault current may be lower than the protection activation value or that the directional element may not be able to correctly identify the fault in the intermediate state.

[0004] Chinese invention patent CN111967740B discloses a method for item-by-item setting, power flow, and error prevention verification of operation tickets. This method ensures the correctness of the operation ticket itself through methods such as interlocking error prevention verification, topology error prevention verification, power flow verification, and equipment status verification after the operation ticket is generated. However, its verification scope is limited to the grammatical correctness of the operation ticket and basic error prevention rules, and does not delve into the protection device level. That is, even if the operation ticket is grammatically correct and the error prevention rules are met, it cannot guarantee that the protection device will reliably operate under actual fault current during operation.

[0005] In summary, existing technologies have made progress in areas such as the selection of tie switches for uninterrupted power supply and the verification of operation tickets to prevent errors. However, they all share common limitations: they fail to use the maintenance operation sequence as an index to determine the identifiability of protection in each intermediate topology state as a release condition. Existing technologies focus primarily on whether the final state after the operation meets power flow constraints, neglecting the risk of insufficient protection sensitivity or primary / backup mismatch caused by sudden changes in power structure in intermediate states. Existing adaptive protection technologies use the current topology for setting switching, but do not bind setting switching to operation steps and establish readback interlocks, resulting in timing gaps. Existing methods primarily output qualitative risk scores, lacking structured certificates, making it difficult to achieve automatic verification and blocking of each operation. Summary of the Invention

[0006] Purpose of the invention: To solve the above-mentioned technical problems, the present invention provides a method and system for uninterrupted maintenance sequence control of medium-voltage distribution networks.

[0007] Technical solution: In a first aspect, this invention discloses a sequence control method for uninterrupted maintenance of medium-voltage distribution networks, comprising the following steps: S1 analyzes the maintenance operation ticket to obtain an operation set consisting of multiple operations in sequence; starting from the initial topology state confirmed on site, each operation generates a series of intermediate topology states in the order of the operation set, wherein the next intermediate topology state is obtained by transferring the previous intermediate topology state through the current operation, and the effective power supply set in the state is determined at the same time as generating each intermediate topology state. S2 establishes a fault contribution model for each effective power source in each intermediate topology state, and then obtains the lower limit and upper limit of the fault current flowing through each protection device in the intermediate topology state. S3 calculates the set of hard margins for each protection device in the intermediate topology state based on the lower limit and upper limit of the fault current. The set of hard margins includes at least: the sensitivity margin of the main protection determined by the minimum fault current and the protection start value, the selectivity margin determined by the time difference between the main protection and the backup protection, and the load separation margin determined by the protection start value and the maximum operating current. S4 takes the minimum value in the set of hard margins as the operation barrier value of the intermediate topology state; if the operation barrier value is not less than zero, a protection identifiability certificate for the intermediate topology state is generated, and the certificate includes at least the applicable protection setting group and the set of prerequisite allowable conditions that must be met before entering the intermediate topology state. Before executing the current operation, S5 reads the field measured data and checks it against the certificate. The execution permission for the current operation is released only when the current set value group read back by the field protection device is consistent with the applicable protection set value group specified in the certificate, the measured electrical quantity is within the range of the pre-permitted condition set, and the operation barrier value is not less than zero. S6 If the operation barrier value is less than zero, a repair action is performed before the current operation is executed, and after the repair, the certificates of all intermediate topology states are recalculated starting from step S1. The repair action includes at least one of switching the temporary protection setting group, adjusting the mobile power supply fault current limiting mode, or rewriting the operation sequence. If there are still intermediate topology states with an operation barrier value less than zero after the repair, the operation sequence is determined to be unexecutable under the current conditions.

[0008] Furthermore, including: The operation items in the operation set include: device identifier, which is a unique ID of a specific operation object; initial state, which is the separate or combined position that the device should be in before executing the operation; target state, which is the separate / combined position that the device should reach after executing the operation; operation type, which is the allowed operation mode; and pre- and post-operations dependencies, which indicate the dependencies that the operation must be executed only after the completion of the preceding operations. The generation of a series of intermediate topological states is represented as follows: ; Where T is the primary device state transition operator. For the operation items in the operation set, Before execution j -1 represents the intermediate topological state after an operation, where J is the total number of operations in the operation set.

[0009] Furthermore, including: The process of constructing the fault contribution model includes: For each intermediate topology state and each preset fault type, short-circuit calculation is performed based on the parameter range of each power source in the effective power source set under that intermediate topology state. The parameter range includes the Thevenin equivalent impedance range converted from the short-circuit capacity range of the upper-level power grid, the subtransient parameter range of the mobile power source, and the fault current limiting range of the inverter-type distributed power source. The fault current boundary contributed by the upper-level power grid is determined based on the Thevenin equivalent impedance range of the upper-level power grid. The fault current contribution range of the mobile power supply is calculated, which is obtained through the subtransient parameter range of the mobile power supply: ; in, For the subtransient fault current of the mobile power supply, This is the rated line voltage of the power bank. This is the maximum value of the subtransient reactance, used to calculate the minimum fault current contribution. This is the minimum value of the subtransient reactance, used to calculate the contribution of the maximum fault current; The fault current limiting range of the inverter-type distributed power source is defined as follows: ; in, This refers to the fault current of an inverter-type distributed power source. This is the lower limit of the fault current limiting factor; This is the upper limit of the fault current limiting factor; This is the rated current of the inverter-type distributed power source.

[0010] Furthermore, including: The process of obtaining the lower limit and upper limit of the fault current flowing through each protection device in this intermediate topology state includes: Based on the current intermediate topology and the current fault type, establish the corresponding short-circuit calculation network; for three-phase short-circuit faults, establish a positive sequence network; for two-phase short-circuit faults, establish a composite sequence network of positive and negative sequences; for single-phase ground faults and two-phase ground faults, establish a composite sequence network of positive, negative, and zero sequences. The endpoint values ​​of the Thevenin equivalent impedance range of the upper-level power grid, the endpoint values ​​of the fault current contribution range of the mobile power supply, the endpoint values ​​of the fault current contribution range of the inverter-type distributed power supply, and the endpoint values ​​of the preset fault resistance range are combined to form multiple sets of parameter combinations. Substitute each set of parameters into the short-circuit calculation network to solve for the fault current value flowing through each protection device under each set of parameters. The minimum value among all calculation results is taken as the lower limit of the fault current, and the maximum value is taken as the upper limit of the fault current.

[0011] Furthermore, including: The step of calculating the hard margin set of each protection device in this intermediate topology state based on the lower limit and upper limit of the fault current includes: The sensitivity margin of the main protection, which is determined by the lower limit of the fault current and the protection start value, is expressed as: ; in, In the intermediate topology state Below, regarding fault types The lower limit of the fault current flowing through the protection device r, For the protection device r in state The starting current used below; The minimum sensitivity coefficient specified; The load separation margin, determined by the protection start value and the maximum operating current, is expressed as: ; in, To protect against starting current; To account for the reliability coefficient of the motor's self-starting and measurement errors; For the boundary interval U in state Formed below, flowing through the protection device r The maximum load current of the branch in which it is located; The selectivity margin between primary and backup protection is determined by the time difference between the actions of the primary and backup protection, and is expressed as: ;in, For fault current variables, In the intermediate topology state Below, regarding fault types f lower limit of fault current ， In the intermediate topology state Below, regarding fault types f The upper limit of the fault current; The operating time of the backup protection under fault current I; The operating time of the main protection under fault current I; To minimize the coordination level difference, it includes the operating time error of backup protection, circuit breaker tripping time, protection return time, and safety margin.

[0012] Furthermore, including: The protection identifiability certificate for generating this intermediate topology state includes: The minimum value in the set of hard margins is taken as the intermediate topological state. Operational barrier value , represented as: ;in, To operate on the barrier value, the subscript j Number the intermediate topology states; and These are the main protection sensitivity margin, load separation margin, main backup selectivity margin, directional element margin, and ground fault identification margin. Normalized reference value for primary protection sensitivity margin The normalized baseline value for load separation margin To minimize the fit grade difference, Normalized reference value for orientation element margin; The normalized margin for the hard constraint on node voltage. Normalized margin for hard constraints on branch current; like A protection identifiability certificate is generated for this state, the protection identifiability certificate including: the applicable protection setting group identifier. and entering intermediate topology state The set of prerequisite conditions that must be met The set of prerequisite allowable conditions Derived from the margin constraint that minimizes the operational barrier value during certificate generation, it at least includes the measured electrical boundary and state conditions that must be satisfied before entering this intermediate topology state, and the applicable protection setting group identifier. This is an identifier for the set value combination that each protection device must use in the current intermediate topology state.

[0013] Furthermore, including: The step of performing a repair action before performing the current operation includes: The switching of the temporary protection setting group includes: selecting the target protection setting group from the pre-configured backup protection setting group, sending a switching command to the field protection device through the communication interface, switching the current setting group to the target protection setting group, reading back to confirm that the switching is completed, synchronously recalculating all margins related to the protection start current, and regenerating the certificates of all intermediate topology states. The adjustment of the mobile power bank fault current limiting mode includes: reading the current mode number through the communication interface, switching it to the target mode number according to the reason for the certificate failure, and after the switching is completed, reading back to confirm that the mode switching is successful, and recalculating the full sequence certificate from the beginning. The rewriting operation sequence includes: identifying adjacent operation pairs in the current operation sequence where two operation objects have no direct electrical dependency and the power supply set and effective short-circuit path do not change after the exchange of any intermediate state; exchanging their execution order; generating a new candidate operation sequence; and restarting the expansion of all intermediate topology states and recalculating the certificates of each state.

[0014] Furthermore, including: The method also includes: When the rewrite operation sequence cannot resolve all certificate failures, the original single operation is broken down into multiple steps, with protection group switching or status confirmation steps inserted between each step. These broken-down operations include: Identify the operations that caused the certificate to fail. And the reasons for its failure, in Insert one or more pre-operations, including at least one of switching protection setting groups, connecting the grounding device, or adjusting the operating mode of the mobile power supply, and read back to confirm that the pre-operations have been completed before executing the original operation. The state conditions corresponding to the pre-operation to be inserted are recorded in the set of pre-allowed conditions for this intermediate state. Before performing the procedure on-site again, each item must be checked.

[0015] Secondly, the present invention also provides a sequence control system for uninterrupted maintenance of medium-voltage distribution networks, the system comprising: The operation ticket parsing module is used to parse maintenance operation tickets and obtain an operation set consisting of multiple operations in sequence; The intermediate topology expansion module is used to apply each operation to the primary device model one by one according to the order of the operation set, starting from the initial topology state confirmed on site, to generate a series of intermediate topology states. The latter intermediate topology state is obtained by transferring the former intermediate topology state through the current operation. At the same time as generating each intermediate topology state, the effective power supply set in that state is determined. The fault contribution modeling module is used to establish a fault contribution model for each effective power source in each intermediate topology state, thereby obtaining the lower limit and upper limit of the fault current flowing through each protection device in the intermediate topology state. The hard margin calculation module is used to calculate the set of hard margins for each protection device in the intermediate topology state based on the lower limit value and the upper limit value of the fault current. The set of hard margins includes at least: the sensitivity margin of the main protection determined by the minimum fault current and the protection start value, the selectivity margin determined by the time difference between the main protection and the backup protection, and the load separation margin determined by the protection start value and the maximum operating current. The certificate generation module is used to take the minimum value in the set of hard margins as the operation barrier value of the intermediate topology state. If the operation barrier value is not less than zero, a protection identifiability certificate for the intermediate topology state is generated. The certificate includes at least the applicable protection setting group and the set of prerequisite allowable conditions that must be met before entering the intermediate topology state. The operation barrier module is used to read the field measured data and verify it with the certificate before executing the current operation. The execution permission of the current operation is released only when the current setting group read back by the field protection device is consistent with the applicable protection setting group specified in the certificate, the measured electrical quantity is within the range of the pre-permitted condition set, and the operation barrier value is not less than zero. The repair module is used to perform a repair action before executing the current operation when the operation barrier value is less than zero, and to re-trigger the intermediate topology expansion module, the fault contribution modeling module, the hard margin calculation module, and the certificate generation module after the repair to recalculate the certificates of all intermediate topology states; the repair action includes at least one of switching temporary protection setting groups, adjusting the mobile power supply fault current limiting mode, or rewriting the operation sequence; if there are still intermediate topology states with operation barrier values ​​less than zero after the repair, it is determined that the operation sequence cannot be executed under the current conditions.

[0016] Thirdly, the present invention also provides a computer device, comprising: one or more processors; The processor is used to store one or more programs; When the one or more programs are executed by the one or more processors, the steps of the uninterrupted maintenance sequence control method for medium-voltage distribution networks as described in the first aspect are implemented.

[0017] Fourthly, the present invention also provides a computer-readable storage medium having a computer program stored thereon, wherein when the computer program is executed, it implements the steps of the uninterrupted maintenance sequence control method for medium-voltage distribution networks as described in the first aspect.

[0018] Beneficial effects: Compared with the prior art, the present invention has the following advantages: (1) This invention expands the operation ticket item by item into a complete sequence of intermediate topology states. For each intermediate state, the fault current range is calculated and the five hard indicators of main protection sensitivity margin, load separation margin, main backup selectivity margin, directional element margin, and ground fault identification margin are checked item by item. Any intermediate state protection failure can be captured by the operation barrier value. The results of parametric Monte Carlo simulation show that the unsafe intermediate state identification rate of final state check alone is 19.0%, and the state-by-state power flow check is 48.0%, while the protection certificate method of this scheme reaches 100.0%, which can completely cover the intermediate state protection mismatch risk.

[0019] (2) This invention embeds the applicable protection setting groups in the certificate and binds them to the current operation item by item. Before operation, it is necessary to read back and confirm that the field protection device has been switched to the setting group specified in the certificate. At the same time, the measured electrical quantity must enter the pre-permission set specified in the certificate. Only when all three conditions are met will the operation permission be released. After the operation is completed, it is also necessary to confirm that the actual state is consistent with the certificate record before proceeding to the next state. This forms a complete closed loop of offline verification, online confirmation, operation release, state confirmation, and progress to the next state, fundamentally eliminating the timing gap between protection group switching and switch operation.

[0020] (3) This invention uses an interval model for the short-circuit capacity of the upstream power grid, the subtransient reactance of the mobile power supply, the fault current limiting multiple of the inverter, and the fault resistance. Short-circuit calculations are performed and extreme values ​​are taken under all parameter endpoint combinations, rather than using only a single typical value. The lower limit of the fault current is used to verify the protection sensitivity under the most unfavorable operating conditions, and the upper limit of the fault current is used to verify the primary and backup selectivity under the most unfavorable operating conditions, ensuring that the certificate is valid under any permissible parameter combination. Compared with the calculation method that only uses typical values, this invention can cover the boundary risks caused by changes in power system operation mode and parameter uncertainty.

[0021] (4) When a certificate fails, the present invention attempts to switch temporary protection setting groups, adjust the mobile power supply fault current limiting mode, exchange operation sequence, and split operation into four levels of repair schemes in order of priority. After each repair, all intermediate state certificates are forcibly recalculated from the first step to ensure global consistency. This mechanism makes the originally unexecutable operation sequence possible to become executable without changing the physical equipment through protection setting adjustment, source side parameter adjustment, or operation sequence optimization. This effectively reduces the rejection of maintenance schemes due to protection coordination problems and improves the feasibility and flexibility of uninterrupted maintenance. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the technology chain described in an embodiment of the present invention; Figure 2 This is a timing diagram of the single-operation barrier check and state progression described in an embodiment of the present invention; Figure 3 This is a diagram illustrating the system structure and interface relationships described in an embodiment of the present invention. Figure 4 This is a schematic diagram showing the distribution of the intermediate state operation barriers as described in the embodiments of the present invention; Figure 5 This is a comparison diagram of the minimum fault current range in the intermediate state and the protection sensitivity requirements described in the embodiments of the present invention; Figure 6 This is a comparison chart of the coverage of the three verification strategies described in the embodiments of the present invention. Detailed Implementation

[0023] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0024] This embodiment provides a sequence control method for uninterrupted maintenance of medium-voltage distribution networks, which includes the following steps: Step 1: parse the operation ticket and expand the intermediate topology state.

[0025] Analyzing the maintenance operation ticket yields a set of operations consisting of J operations in sequence. Each of these operations It includes device identifier, initial state, target state, operation type, and dependencies.

[0026] Based on the initial topology confirmed on site Starting from the first operation, each operation is applied to the primary device model sequentially according to the order of the operation set, generating a series of intermediate topology states. Each subsequent intermediate topology state is obtained by transitioning from the previous intermediate topology state through the current operation. (1-1) Where T is the primary device state transition operator. For the operation items in the operation set, Before execution j -1 represents the intermediate topological state after an operation, where J is the total number of operations in the operation set.

[0027] Generate each intermediate topology state Simultaneously, the effective power source set under this state is determined, that is, the power sources that maintain electrical connection with the system and can inject short-circuit current into the fault point under this topology state, including the upstream grid, mobile power sources, and inverter-type distributed power sources that are still in grid-connected / generating state. At the same time, a preset fault type set F is obtained, which includes phase-to-phase short-circuit faults, three-phase short-circuit faults, and single-phase ground faults. In this embodiment, the mobile power source can be a synchronous generator vehicle, a mobile energy storage converter, or a combination of both.

[0028] Step 2: Construct the source-side fault contribution range and calculate the fault current range of the protection device.

[0029] For each intermediate topology state And for each of the preset fault types f, short-circuit calculations are performed based on the parameter ranges of each power source in the effective power source set under the intermediate topology state. The specific method of the short-circuit calculation is as follows: establish a corresponding sequence network according to the fault type, take the endpoint values ​​of the equivalent impedance range of the upper-level power grid, the fault current contribution range of the mobile power source, the fault current contribution range of the inverter-type distributed power source, and the preset fault resistance range for full combination, perform short-circuit calculations respectively, take the minimum value among all calculation results as the lower limit of the fault current, and take the maximum value as the upper limit of the fault current, so as to obtain the lower limit of the fault current and the upper limit of the fault current flowing through each protection device under the intermediate topology state.

[0030] The parameter range includes the Thevenin equivalent impedance range converted from the short-circuit capacity range of the upper-level power grid, the subtransient parameter range of the mobile power source, and the fault current limiting range of the inverter-type distributed power source.

[0031] In this embodiment, the Thevenin equivalent impedance range of the upstream power grid is obtained by the following formula: (2-1) in, The Thevenin equivalent impedance Ω, To connect to the busbar rated voltage kV, This refers to the short-circuit capacity (MVA) at the connection to the busbar. The maximum short-circuit capacity is... To produce minimum equivalent impedance Used to calculate maximum fault current; minimum short-circuit capacity. Generate maximum equivalent impedance , used to calculate the minimum fault current.

[0032] The fault current contribution range of the mobile power supply is calculated from the secondary transient parameter range using the following formula: (2-2) in, For the subtransient fault current of the mobile power supply, This is the rated line voltage of the power bank. This represents the maximum value of the subtransient reactance, used to calculate the minimum fault current contribution. (Subscript) d Indicates the direct axis. This is the minimum value of the subtransient reactance, used to calculate the contribution of the maximum fault current; The fault current contribution range of an inverter-type distributed generation source is calculated from its fault current limiting range using the following formula: (2-3) in, The fault current in kA for inverter-type distributed power sources is given by the subscript. pv Indicates a photovoltaic inverter; This is the lower limit of the fault current limiting factor, dimensionless, and indexed. I The superscript indicates the lower limit; This is the upper limit of the fault current limiting factor, dimensionless, with the superscript + indicating the upper limit; The rated current (kA) of the inverter-type distributed power source is given by the subscript. N Indicates the rated value.

[0033] The fault current contribution range of each of the above power sources, combined with the preset fault resistance range. ,in, Minimum fault resistance, Maximum fault resistance, subscript f Indicating a fault, after interval short-circuit calculation, the unified output is the state of the intermediate topology. Below, regarding fault types f Flowing through each protective device r lower limit of fault current and the upper limit of fault current Subscript r Indicates the protection device number r =1,2,…, R , R This represents the total number of protection devices participating in the verification under this intermediate topology state; subscriptj This is the intermediate topology state number. j =0,1,2,…, J Before the corresponding operation sequence is completed j The state after the operation; subscript f Number the fault type f ∈ F , F This is a preset set of fault types. In this embodiment, the lower limit of the fault current is used to verify whether the protection can reliably start under the most unfavorable operating conditions; the upper limit of the fault current is used to verify whether the operating sequence of the main protection and the backup protection meets the selectivity requirements under the most unfavorable operating conditions.

[0034] Step 3: Calculate the protection sensitivity margin, load separation margin, and selectivity margin.

[0035] According to the lower limit of the fault current and the upper limit of fault current Calculate each protection device r In this intermediate topology state The set of hard margins. The set of hard margins includes at least the following three types: (a) Main protection sensitivity margin Msen The value is determined by the minimum fault current and the protection activation value, and is calculated using the following formula: (3-1) in, In the intermediate topology state Below, regarding fault types f Flow through protection device r The lower limit of the fault current is the value of the protection device. r In state The starting current used below; Main protection sensitivity margin, dimensionless, subscript sen Indicates sensitivity. For protection devices r In state The starting current used below is kA, and the subscript is... set Indicates the startup value. r To protect the serial number, j For status numbers; The minimum sensitivity coefficient (dimensionless) is specified by the subscript. sen Indicates sensitivity. min This represents the minimum value, which is usually between 1.3 and 1.5. A value less than zero indicates that the protection may fail to operate under the most unfavorable fault current.

[0036] (ii) Load separation margin, which is determined by the protection start value and the maximum operating current, is expressed as: (3-2) in, To protect against starting current; to consider the reliability coefficient for motor self-starting and measurement errors; to define the operating boundary range U in state The maximum load current formed below and flowing through the branch where the protection device r is located; This is the load separation margin, dimensionless, subscripted. sep Indicates separation. r To protect the serial number, j For status numbers; To protect against starting current kA; To account for the reliability coefficient of motor self-starting and measurement error, dimensionless, subscript... load Indicates load; For the running boundary interval in state Formed below, flowing through the protection r The maximum load current kA of the branch is max This represents the maximum value. A value less than zero indicates that normal load or power supply surges may cause the protection system to malfunction.

[0037] (iii) The selectivity margin between primary and backup protection is determined by the time difference between the actions of the primary and backup protection, and is expressed as: (3-3) in, For fault current variables, In the intermediate topology state Below, regarding fault types f lower limit of fault current ， In the intermediate topology state Below, regarding fault types f The upper limit of the fault current; subscripts are omitted here. r This indicates that it refers to a specific primary and backup protection pair. The operating time of the backup protection under fault current I; The operating time of the main protection under fault current I; For the minimum fit grade difference, the subscript is... CTI Indicates the time interval between coordination activities. min This represents the minimum value, which includes the circuit breaker tripping time, protection return time, and safety margin; it is typically taken as 0.2–0.5 seconds. A value less than zero indicates that a cascading trip may occur between the primary and backup protection systems.

[0038] For the inverse-time overcurrent characteristic of the IEC standard, the operating time is calculated by the following formula: (3-4) in, This is a time multiplier, dimensionless;A and p The shape parameter of the inverse time-limited curve is dimensionless. The time limit delay is measured in seconds. If the field device uses a manufacturer-defined curve, the device curve table will be directly called, and the action time will be calculated at all segment endpoints.

[0039] It should be noted that the protection starting current... The sensitivity margin that also appears in formula (3-1) The load separation margin of formula (3-2) In the calculation of the action time in formula (3-4), the action time further affects the selectivity margin of formula (3-3). Therefore, when the system needs to switch temporary protection setting groups for repair, all the above-mentioned margins must be recalculated and the certificate must be regenerated simultaneously. It is prohibited to modify the starting current value in isolation in the protection setting parameter table without rechecking other margins.

[0040] Step 4: Calculate the directional element margin and the ground fault identification margin, and generate the operational barrier value and protection identification certificate.

[0041] (iv) Orientation element margin The minimum directional torque under the most unfavorable source combination. relative to the starting torque of the directional element Normalized, it is calculated using the following formula: (4-1) in, For directional element margin, dimensionless, subscript dir Indicates direction; For flow protection r The directional element is in the intermediate state Fault type f The minimum directional torque among all permissible parameter combinations, dimensionless, with the superscript − indicating the minimum value; The starting torque of the directional element is dimensionless and indicated by a subscript. set This indicates the startup value. A value less than zero indicates that under the most unfavorable conditions, the directional element may be unable to correctly determine the direction of the fault, leading to directional overcurrent or directional grounding protection failure.

[0042] (v) Grounding fault identification margin For protections that rely on the zero-sequence direction, such as zero-sequence direction overcurrent protection, the minimum zero-sequence direction power is normalized relative to the zero-sequence direction power starting value to obtain the following: (4-2) in, The ground fault identification margin based on the zero-sequence direction criterion is dimensionless and subscripted. gnd Indicates grounding, superscript dir Indicating direction criteria For flow protection r The minimum zero-sequence directional power in all permissible parameter combinations, W or Var, with the subscript 0 indicating zero sequence; Zero-sequence directional power starting value, W or Var, subscript set This indicates the startup value.

[0043] For protections that rely on the magnitude of the zero-sequence current, such as zero-sequence overcurrent protection, the minimum value is three times the zero-sequence current. Relative to zero-sequence current starting value And deduct the minimum zero-sequence sensitivity coefficient required by the procedure for calculation: (4-3) in, The ground fault identification margin based on the zero-sequence current amplitude criterion is dimensionless and superscripted. I Indicates the current amplitude criterion. For flow protection r The minimum value (kA) of three times the zero-sequence current among all permissible parameter combinations. To protect r In state The zero-sequence starting current (kA) is given below, where the subscript 0 indicates zero sequence. The specified minimum zero-order sensitivity coefficient, dimensionless, with the subscript 0 indicating zero order. sen Indicates sensitivity. min This represents the minimum value, which is usually between 1.3 and 1.5. "At zero" indicates that after islanding or changes in grounding method, the original zero-sequence protection may lose its ability to identify single-phase grounding faults.

[0044] (vi) Generation of operational barrier values ​​and protection identifiability certificates. The minimum value in the set of hard margins is taken as the intermediate topology state. Operational barrier value : (4-4) in, To operate on the barrier value, the subscript j Number the intermediate topology states; and These are the main protection sensitivity margin, load separation margin, main backup selectivity margin, directional element margin, and ground fault identification margin. Normalized reference value for primary protection sensitivity margin The normalized baseline value for load separation margin To minimize the fit grade difference, Normalized reference value for orientation element margin; The normalized margin for the hard constraint on node voltage. Normalized margin for hard constraints on branch current; It is the minimum value after normalization of all hard margins.

[0045] like This intermediate topological state is then generated. Protective identifiability certificate The certificate At least includes: (1) Current state The device status list is used as a comparison benchmark for actual status verification after the operation is completed, to confirm whether the system has indeed entered the intermediate topology state corresponding to the certificate. (2) Applicable protection setting group Rj It is used to check whether the field protection device has been switched to the set value group required by the certificate before operation; (3) Entering this intermediate topology state The set of prerequisite conditions that must be met Aj It is used to verify whether the measured electrical quantities on site meet the boundary conditions specified in the certificate before operation; (4) The current range and margin value under each fault scenario, which serve as the basis for the calculation of the certificate and are used for traceability and auditing.

[0046] like If the condition is met, it means that at least one hard constraint has failed, and you need to proceed to step six for repair.

[0047] Step 5: Implement each step on-site using operational barriers.

[0048] Execute the current operation Previously, the on-site measured data was read and compared with the certificate. Verify. The current operation will only be released if all of the following conditions are met simultaneously. Execution license: (1) The current setting group read back by the field protection device and the applicable protection setting group specified in the certificate. Consistent; (2) Measured electrical quantities, including branch currents and node voltages, are within the aforementioned set of preconditions. Within the range; (3) The operation barrier value .

[0049] After the operation is completed, the system waits for confirmation of both switch positions and checks whether the actual status matches the certificate. Recorded in The equipment status list must be consistent; otherwise, the status may be inconsistent, the operation may time out, or the actual measurement may exceed the certificate. If the operation maintains a specified range, subsequent operations are immediately blocked, and execution is not allowed to continue in an unknown intermediate state. This only applies if the switch's dual-position state matches the state in the certificate. The system will only move the current status pointer from the list of devices that match the current status list. Advance to Now, we are ready to perform the next operation.

[0050] In this embodiment, the set of preconditions is allowed. The generation method is as follows: before pushing back from the margin constraint that leads to the minimum operation barrier value into the intermediate topology state, the measured boundary and state conditions that must be satisfied must be met; wherein, the measured boundary includes at least one of the upper limit of branch current and the lower limit of node voltage, and the state conditions include at least one of the protection setting group identifier, grounding device status, and mobile power supply operation mode; The set of preconditions Execute the current operation Previously read and compared with the actual measured data on site: when the measured branch current and node voltage are both within Within the specified boundaries, and the current setting group read back by the field protection device matches the applicable protection setting group specified in the certificate. Consistency, grounding device status and mobile power supply operating mode When the conditions specified in the document are consistent with those in the document, that part of the condition is considered to be satisfied; Each condition is a hard threshold, and each item is checked individually. Weighted scoring or fuzzy comprehensive judgment is not used.

[0051] In one specific preferred embodiment, from the resulting Starting from the smallest margin constraint, work backwards to find the measured boundary conditions that must be met before reaching that state. For example: if the minimum margin is... And due to the maximum load current I load,max If determined, the upper limit of the branch current can be calculated by the system. Subtracting the safety margin, this upper limit enters If the minimum margin is Furthermore, due to insufficient contribution from generator car malfunctions, the system inversely determines that the generator car must be in islanded voltage source preparation mode or fault current limiting mode has been switched. This condition triggers the system's entry point. If the minimum margin is Furthermore, determined by insufficient zero-sequence current or zero-sequence directional power, the system inversely determines the conditions under which the neutral point grounding resistance has been activated or the zero-sequence protection direction has been adapted to islanding mode. This condition then enters... If the minimum margin is Furthermore, if the directional torque is insufficient, then the system's reverse directional element has switched to the bidirectional protection group or the tie power direction has been confirmed, and this condition is entered. . Each condition is a hard threshold, and each item will be checked one by one during the on-site test. No weighted scoring will be used.

[0052] Step 6: Repair and recalculation after certificate failure.

[0053] If the operation barrier value Then, while performing the current operation First, perform the repair action, and then recalculate the certificates for all intermediate topology states starting from the first step after the repair.

[0054] The repair actions are generated as candidates in the following priority order: Level 1 repair: Switch temporary protection setting group.

[0055] The system queries the pre-configured backup protection setting group. Taking the numerical example of this application, in protection group A... The starting value is 0.62kA, calculated as follows: Certificate failed; system switched to protection group B. The startup value dropped to 0.50 kA. Restored to 0.140. However, a recalculation is required after the switch. and If the protection group is switched Msel It becomes a negative value, such as under protection group B. If so, the backup protection time multiplier needs to be adjusted simultaneously.

[0056] like or If the system fails, it will switch to a protection setting group that adapts to the current intermediate topology state directional characteristics or grounding method.

[0057] If switching a single protection group is insufficient to restore the full margin, the system can combine and switch multiple protection groups and re-execute the calculations in steps two through four.

[0058] After switching the protection setting group, the system must synchronously recalculate all related settings. The relevant margin is , and And regenerate the certificate; you must not modify the startup value in isolation in the parameter table without re-verifying it.

[0059] Level 2 Repair: Adjust the power bank's fault current limiting mode.

[0060] For power banks with multiple fault current limiting modes, the system reads the current mode number through the communication interface and switches it to the target mode number based on the certificate failure reason. For example, if The system failed due to insufficient fault current contribution from the power bank; therefore, it switched the power bank to a current-limiting mode that can provide a larger fault current contribution. If the fault current is too large, resulting in insufficient time difference between the primary and backup actions, the system switches to a current-limiting mode that reduces the peak fault current. After the switch is complete, the system reads back to confirm the successful switch and recalculates the full sequence certificate from the first step.

[0061] Level 3 Repair: Swap the operation order.

[0062] The system identifies adjacent operation pairs in the current operation sequence that meet the following conditions: the two operation objects have no direct electrical dependency, and the power supply set and effective short-circuit path of any intermediate topology state do not change after the order is swapped. For adjacent operation pairs that meet the conditions, the system swaps their execution order, generates a new candidate operation sequence, and re-expands all intermediate topology states starting from the first step, recalculating the certificate of each state. If all of the new sequence... If all operations are restored to non-negative, a new sequence is used; if a negative barrier still exists, continue to try swapping other adjacent operation pairs or proceed to the next level of repair.

[0063] Level 4 repair: Split operation.

[0064] When the sequence of operations cannot resolve all certificate failures, the system breaks down the original single operation into multiple steps, inserting protection group switching or status confirmation steps between each step.

[0065] The specific implementation method of the splitting operation is as follows: the system identifies the operation that caused the certificate to fail. And the reasons for its failure, in Insert one or more pre-operations, including at least one of switching protection setting groups, connecting the grounding device, or adjusting the operating mode of the mobile power supply, and read back to confirm that the pre-operations have been completed before executing the original operation. The state conditions corresponding to the inserted pre-operation (such as protection setting group being switched, grounding resistance being engaged, measured electrical quantity being within the specified boundary, etc.) are recorded in the set of pre-permitted conditions for this intermediate state. The fifth step involves checking each item one by one before on-site execution.

[0066] Level 5 Repair: Determined as unexecutable.

[0067] If none of the above four-level repair schemes can restore all intermediate topology states Restore the value to a non-negative value, output the conclusion that the maintenance plan is not feasible under the current conditions, and switch to other power supply methods, such as power outage maintenance.

[0068] For any of the above repair actions involving switching protection setting groups or adjusting the power bank's operating mode, it must be confirmed that the on-site execution has been completed and successfully read back before recalculating the certificate. After each repair, certificates for all intermediate topology states should be regenerated starting from step one, rather than just recalculating the single failed state, to ensure global consistency.

[0069] This embodiment is based on the above six steps and will be described in further detail with reference to the accompanying drawings, but the implementation of the present invention is not limited thereto. I. Operation Ticket Parsing and Intermediate Topology State Deployment

[0070] like Figure 1 As shown, this invention first parses the operation items in the maintenance work order into an ordered set of operations, based on the ground state confirmed on-site. Starting from this point, operations are applied item by item to obtain intermediate topological states. Specifically, such as... Figure 1 In the technology chain shown, Figure 1 The complete technical chain of "operation sequence expansion → intermediate state fault interval → protection hard margin → certificate generation → item-by-item barrier execution" is shown. Step S1 completes the operation sequence expansion to obtain the intermediate topology state sequence, step S2 performs interval short circuit calculation to obtain the upper and lower limits of the fault current, steps S3 to S4 calculate the five hard margins and generate a certificate, and steps S5 to S6 complete the field barrier execution and repair.

[0071] Read the operation set Ω from the maintenance work order and operation ticket system. Each operation... The data structure should at least include: device identifier, such as K3, K7, etc.; initial state (open or closed); target state (open or closed); operation type, such as "closing", "opening", "parallel", etc.; and dependencies, such as "O3 must be...". Execute after completion.

[0072] Obtain primary equipment model data from the distribution automation master station or a manually verified single-line diagram, including: node number and type, branch start and end nodes and positive / negative / zero sequence impedance, transformer capacity and short-circuit impedance, switchgear ID and two-end nodes. Ground state. The current operating mode, as confirmed on-site, is generated by reading the dual-position contact status of all switches in the distribution automation master station.

[0073] Generate intermediate topology states item by item in the following manner: by Starting from, read . Chinese equipment identification is (Generator parallel switch), target state is "closed". The system is in... Search in the model Change its state from "separated" to "combined", while keeping the states of all other devices unchanged, and generate... Then read ,Will Write after modifying the status of the corresponding device ,generate And so on, until generated .

[0074] Generate each At the same time, the system performs a power connectivity scan: starting from each power source point in the model (upstream grid inlet, generator grid connection point, photovoltaic grid connection point), a graph search is performed along all closed branches to record the power sources that can reach the load area or fault area, forming the effective power source set for that state. If the outlet switch of a power source is in the open position, or if there is no path consisting entirely of closed branches from the power source to the load area, then the power source is not included in the effective power source set.

[0075] Simultaneously, a preset set of fault types F is obtained, including: three-phase short-circuit fault, two-phase short-circuit fault, two-phase-to-ground short-circuit fault, and single-phase-to-ground fault, as well as a preset fault resistance range. .

[0076] It should be noted that the refresh cycle of field data acquisition must meet the following requirements: the refresh cycle of switch and protection group status should not exceed 1 second; the refresh cycle of current and voltage RMS values ​​should not exceed 1 second; the refresh cycle of phasors used for directional elements or synchronous auxiliary judgment should be consistent with the capability of the field device. Real-time data with timestamps must be collected before and after operation. After operation, it is also necessary to collect switch opening and closing SOE, two sets of position contacts, protection group readback, mobile power supply mode readback, and voltage and current for multiple consecutive sampling cycles after operation. II. Calculation of Source-Side Fault Contribution Range

[0077] For the current intermediate topology state First, read the set of valid power sources in that state.

[0078] It should be noted that the mobile power source can be a synchronous generator vehicle, a mobile energy storage converter, or a combination of both. This embodiment uses a synchronous generator vehicle as an example for illustration, but the invention is not limited thereto. For the mobile energy storage converter, its fault current contribution characteristics are similar to those of the inverter-type distributed power source, and a current-limiting interval model can be used for modeling.

[0079] For the upstream power grid, the system obtains the minimum short-circuit capacity of the access bus under the current operating mode from the dispatching department. and maximum short-circuit capacity Calculate the minimum equivalent impedance according to formula (2-1). ,correspond and maximum equivalent impedance ,correspond This forms the Thevenin equivalent impedance range. This impedance range serves as a fault contribution model for the upstream power grid and directly participates in subsequent short-circuit network calculations.

[0080] For mobile power supplies (taking synchronous generator vehicles as an example), the system reads the following parameters from the nameplate, factory test report, or field controller: rated capacity. (kVA), rated line voltage (kV) Subtransient reactance Upper and lower limits and (pu or Ω). Substituting this into formula (2-2), the subtransient fault current range injected by the generator into the fault point can be calculated. If the generator car is connected to the busbar via an outlet transformer, the impedance of the outlet transformer needs to be converted and connected in series with the equivalent impedance of the generator car.

[0081] For inverter-type distributed power sources (taking photovoltaic inverters as an example), the system reads the rated current from the parameters provided by the manufacturer or the low voltage ride-through test report. and the lower limit of the fault current limiting multiple and upper limit Substituting this into formula (2-3), the fault current range injected by the photovoltaic inverter into the fault point can be calculated. The inverter's fault current is not affected by network impedance, and its magnitude is actively limited by the control strategy, so no further calculation is required.

[0082] After completing the fault contribution models for each power source, the system performs interval short-circuit calculations. The steps are described below: Step A: Establish a short-circuit calculation network.

[0083] For the current intermediate topology state The system establishes a short-circuit calculation network based on the topology of the current state, including the connectivity of each branch, transformer connection methods, and the status of grounding devices. For three-phase short-circuit faults, only a positive-sequence network is established; for two-phase short-circuit faults, a composite positive-sequence and negative-sequence network is established; for two-phase-to-ground short-circuit faults and single-phase-to-ground faults, a composite positive-sequence, negative-sequence, and zero-sequence network is established. When establishing each sequence network, the Thevenin equivalent impedance of the upstream power grid is placed at the equivalent impedance position on the system side, the subtransient reactance of the mobile power source and its negative-sequence and zero-sequence reactance are placed at the corresponding power source branch positions in the respective sequence networks, and the inverter-type distributed power source is placed as a controlled current source at its grid connection node position.

[0084] Step B: Enumerate all combinations of endpoints of the parameter range.

[0085] The system takes the endpoint values ​​of each parameter interval and performs a full combination. The objects enumerated here are the endpoint values ​​of each power source fault contribution interval already calculated in the second step, not the original parameters. Specifically, these are: the minimum and maximum values ​​of the Thevenin equivalent impedance interval of the upstream power grid, the minimum and maximum values ​​of the mobile power source fault current contribution interval calculated in the second step, the minimum and maximum values ​​of the inverter-type distributed power source fault current contribution interval calculated in the second step, and the minimum and maximum values ​​of the preset fault resistance interval. The endpoint values ​​of these parameters are combined using Cartesian products to form N sets of parameter combinations.

[0086] Step C: Calculate the short-circuit current for each set of parameters.

[0087] For each set of parameters, the system substitutes it into the short-circuit calculation network established in step A, and solves the network using the symmetrical component method or the phase component method. This yields the fault current values ​​flowing through each protection device r under that parameter combination, for fault type f, including the current values ​​of each sequence component, as well as derived quantities such as the directional torque and zero-sequence directional power required by the directional elements. For three-phase short-circuit faults, the positive-sequence equivalent rule is used for solution; for asymmetrical faults, the composite sequence network method is used.

[0088] Step D: Take the minimum and maximum values ​​from all the calculation results.

[0089] After traversing all N sets of parameter combinations, the system obtains the flow protection. r Fault current value set The minimum value of this set is taken as the lower limit of the fault current. The maximum value is taken as the upper limit of the fault current. Similarly, the minimum and maximum values ​​of derived quantities such as directional torque, zero-sequence current, and zero-sequence directional power are taken respectively, and used in the subsequent fourth step. and The calculation.

[0090] Step E: Record the parameter combinations that generate endpoint values.

[0091] The system simultaneously records the generation and The specific parameter combination corresponding to that time, including the equivalent impedance value of the upstream power grid, the subtransient reactance value of the mobile power supply, the current limiting multiple of the inverter, and the fault resistance value, serves as the certificate. j The basis for the margin calculation is to locate the source of the most unfavorable operating condition parameters that lead to insufficient margin in subsequent steps. III. Protection Margin Calculation

[0092] Based on the output of the second step and For each protection device r, calculate the following three hard margins one by one.

[0093] (a) Main protection sensitivity margin Msen Calculation method: The system reads the current intermediate topology state of the protection device. Starting current The starting current is determined by the currently selected protection setting group. The system obtains the specified minimum sensitivity coefficient. Substituting the values ​​into formula (3-1), if the calculated result is less than zero, it indicates that under the most unfavorable fault current, the ratio of the actual fault current to the starting current is lower than the minimum sensitivity coefficient required by the regulations, and the protection may not be able to start (fail to operate) under this condition. At this time, the system marks the cause of failure as insufficient sensitivity of the main protection.

[0094] (ii) Load separation margin Calculation method: Read the status of the branch where protection r is located. Maximum load current This value is obtained by taking the 5% to 95th percentile values ​​of the load range after generating the load range from the continuous measurement data of 15 to 30 minutes before operation, and adding the measurement error. For branches containing motors, the motor restart inrush current also needs to be taken into account.

[0095] System obtains reliability coefficient Typically, a value of 1.1 to 1.25 is used. Substituting this value into formula (3-2), if the calculated result is less than zero, it indicates that the protection starting current is lower than the maximum load current amplified by the reliability factor. The protection may erroneously start (maloperate) under normal load or during motor self-starting. In this case, the system marks the cause of the failure as "insufficient load separation".

[0096] (III) Primary and backup selectivity margin Calculation method: Determine the main protection r p and its backup protection r b The pairing relationship. For each fault type f, the system in the current range The minimum coordination time difference is calculated as follows: First, the system obtains the operating characteristic curve of the protection device. For the IEC standard inverse-time characteristic, the operating time is given by formula (3-4). Then, the system selects the key calculation point within the current range: the lower limit of the fault current. Fault current upper limit And the inflection point current value of the protection action characteristic curve. Calculate the main protection for each calculation point separately. rp and backup protection r b Substitute the action time into formula (3-3). A value less than zero indicates that at the most unfavorable current point, the time difference between the main protection and the backup protection is less than the minimum coordination level difference, which may lead to cascading tripping. In this case, the system marks the cause of the failure as insufficient selectivity between the main and backup protection.

[0097] (iv) Explanation of the linkage constraints for protection starting current: Protect starting current Iset , r , j The sensitivity margin that also appears in formula (3-1) The load separation margin of formula (3-2) In the calculation of the action time in formula (3-4), the action time further affects the selectivity margin of formula (3-3). Therefore, when the system switches temporary protection setting groups during the sixth step of the repair process, all the above-mentioned margins must be recalculated simultaneously, and the fourth step must be re-executed to generate a new certificate. It is prohibited to modify the starting current value in isolation from the protection setting parameter table without re-verifying other margins. IV. Calculation and Certificate Generation of Directional Component Margin and Ground Fault Identification Margin

[0098] This embodiment forms a complete closed loop of data acquisition → formula calculation → certificate generation → physical action execution.

[0099] Calculate the operational barrier value using formula (4-4). , It is the minimum value after normalization of all hard margins; any missing or insufficient margin will be directly reflected in the minimum value. A decrease or a negative value cannot be offset by other terms.

[0100] like The system generates a protection identifiability certificate for this state. The certificate's data structure must at least include the following interfaces: (1) State record: Includes state identifier stateId (corresponding to and operation sequence number j ), previousStateId, operationId, closedBranchIds, openBranchIds, activeSourceIds, groundingMode, primaryBackupPairs, and expectedSwitchFeedback.

[0101] (2) Certificate record: Includes the state identifier stateId, model version number modelVersion, and the applicable protection setting group identifier, i.e. The collection of fault cases, current interval records, margin items, and operation barrier values ​​(i.e., fault case collection, currentIntervals, marginItems, and barrierValue). ), the set of prerequisite allowable conditions (i.e. ), repair actions list repairActions, rollback action rollbackAction, certificate validity period validFrom and validUntil.

[0102] (3) Fault Cases: Each fault case record includes the fault branch identifier, fault location ratio (0~1), fault type, and fault resistance range. .

[0103] (4) Current range record: including protection device ID and lower limit of fault current. Fault current upper limit and the generation I - and I The specific parameter combination corresponding to + is: the equivalent impedance value of the upstream power grid, the subtransient reactance value of the mobile power supply, the current limiting multiple value of the inverter, and the fault resistance value.

[0104] (5) Margin records: including margin types Value, unit, limit, corresponding protection device number, failure reason code. V. On-site execution and progress tracking

[0105] like Figure 2 As shown, the sequence of single-operation barrier checks and status advancement is as follows: certificate verification → pre-operation readback confirmation → release operation → execute switch operation → post-operation status confirmation → status pointer advances to the next state.

[0106] In performing operations Previously, the field controller read the certificate. Protection setting group identifier Pre-permitted set and operation barrier value The system collects the following real-time data from the site: The current setting group number and pressure plate status of relevant protection devices, the status of the double-position contacts of relevant switches, the effective value of the three-phase current of critical branches, the effective value of the three-phase voltage (including zero-sequence voltage) of critical nodes, the on / off status of grounding devices, and the operating mode number of the mobile power supply. The current torque or direction determination result of the directional element.

[0107] Perform the following judgments in sequence: Condition 1: The current setting group number read back by the protection device is the same as... Consistent.

[0108] Condition 2: The measured branch current, node voltage, and other electrical quantities are all within the range specified in the original text. Within the prescribed scope.

[0109] Condition three: .

[0110] The system returns a permission signal to the operation ticket system and releases the operation only when all three conditions are met. .

[0111] Post-operation status confirmation and status progression: operate After execution, the system waits for feedback from the switch's dual-position contacts and checks whether the actual switch status matches the certificate. Recorded in The device status list is consistent. Specifically: If the two sets of switch contacts are consistent and match the certificate... The target location is consistent with the equipment status list; The protection device setting group readback is still... (No unexpected jump occurred); After the operation, the voltage and current for three consecutive sampling periods are within the certificate range. Allowed operations will remain within the specified range; The system then confirms that the system has indeed entered the certificate. The corresponding intermediate topological state Move the current state pointer from Advance to Now, we are ready to perform the next operation.

[0112] If any of the above conditions are not met, including inconsistency between switch position contacts, operation timeout, or discrepancy between the actual switch status and the certificate status, then the switch is in a different state. If the equipment status list is inconsistent, a protection group trips unexpectedly, or a voltage drop exceeds the range, the system will immediately block subsequent operations and will not advance the status pointer to the specified value. The system will either execute the rollback operation pre-stored in the certificate or maintain the current state pending manual intervention. The system does not allow execution to continue in an unknown intermediate state.

[0113] It should be noted that the interface communication between modules follows the following data specifications: all interface data must carry the device ID, timestamp, model version, and data source identifier to avoid misuse of settings for devices with the same name or older versions. System interfaces must include at least the following: interfaces for reading operation items from the operation ticket system; interfaces for reading equipment and impedance from the distribution network model platform; interfaces for obtaining interval endpoint results from the short-circuit calculation service; interfaces for reading and switching setting groups from the protection setting management system; interfaces for obtaining switch and electrical quantities from the distribution automation master station; and interfaces for returning permission / lockout / revert commands to the field controller. VI. Repair and Recalculation after Certificate Failure

[0114] The implementation steps and data transmission process of this embodiment are as follows: S1 Generate intermediate state sequence → S2 Calculate fault current range → S3 Calculate protection margin → S4 Generate certificate → S5 On-site execution and barrier check → S6 Repair and recalculate after certificate failure. A close data transmission relationship is formed between each step.

[0115] when When this happens, the system generates repair candidate solutions according to the following priorities.

[0116] Level 1 repair: Switch temporary protection setting group.

[0117] The system queries the pre-configured backup protection setting group. Taking the numerical example of this application, in protection group A... R The starting value is 0.62kA, calculated as follows: Certificate failed; system switched to protection group B. R 3. The startup value drops to 0.50kA. Restored to 0.140. However, a recalculation is required after the switch. and If the protection group is switched Msel It becomes a negative value, such as under protection group B. If so, the backup protection time multiplier needs to be adjusted simultaneously.

[0118] like and If the system fails, it will switch to a protection setting group that adapts to the current intermediate topology state directional characteristics or grounding method.

[0119] If switching a single protection group is insufficient to restore the full margin, the system can combine and switch multiple protection groups and re-execute the calculations in steps two through four.

[0120] After switching the protection setting group, all related settings must be recalculated synchronously. The relevant margin, i.e. , and And regenerate the certificate; you must not modify the startup value in isolation in the parameter table without re-verifying it.

[0121] Level 2 Repair: Adjust the power bank's fault current limiting mode.

[0122] For power banks with multiple fault current limiting modes, the current mode number is read through the communication interface, and the power bank is switched to the target mode number based on the certificate failure reason. For example, if The power bank failed due to insufficient fault current contribution. Switch the power bank to a current-limiting mode that can provide a larger fault current contribution. If the fault current is too large, resulting in insufficient time difference between the primary and backup actions, the system switches to a current-limiting mode that reduces the peak fault current. After the switch is complete, the system reads back to confirm the successful switch and recalculates the full sequence certificate from the first step.

[0123] Level 3 Repair: Swap the operation order.

[0124] Identify adjacent operation pairs in the current operation sequence that meet the following conditions: the two operations have no direct electrical dependency, and the power supply set and effective short-circuit path of any intermediate topology state do not change after the order is swapped. For adjacent operation pairs that meet the conditions, swap their execution order to generate a new candidate operation sequence, and re-expand all intermediate topology states starting from the first step, recalculating the certificate of each state. If the new sequence contains all... If all operations are restored to non-negative, a new sequence is used; if a negative barrier still exists, continue to try swapping other adjacent operation pairs or proceed to the next level of repair.

[0125] In one embodiment, the original sequence is: O 1 generator car in parallel → O 2 breaks K 3→ O 3-in-1 K 7→ O 4 breaks K 4. After the generator cars are paralleled G 1. If executed in the original order O 2 (cut off first) K 3) In the intermediate state, power is supplied to the load solely by the generator car. K The 7-directional protection has not yet established reverse polarity. Certificate failed. The system attempted to exchange. O 2 and O The order of 3 forms a new sequence. O 1→ O 3-in-1 K 7→ O 2 breaks K 3→ O 4 breaks K 4. But inG 2 (together) K (After 7), short-term dual-path parallel supply leads to primary and backup selectivity. The certificate also failed. At this point, the system enters the next level of repair.

[0126] Level 4 repair: Split operation.

[0127] When the sequence of operations cannot resolve all certificate failures, the system breaks down the original single operation into multiple steps, inserting protection group switching or status confirmation steps between each step.

[0128] The specific implementation method of the splitting operation is as follows: the system identifies the operation that caused the certificate to fail. And the reasons for its failure, in Insert one or more pre-operations, including at least one of switching protection setting groups, connecting the grounding device, or adjusting the operating mode of the mobile power supply, and read back to confirm that the pre-operations have been completed before executing the original operation. The state conditions corresponding to the inserted pre-operation, such as the protection setting group being switched, the grounding resistance being engaged, and the measured electrical quantity having entered the specified boundary, are recorded in the set of pre-permitted conditions for this intermediate state. The fifth step involves checking each item one by one before on-site execution.

[0129] Taking the continuation of Embodiment 2 of this application as an example: after exchanging the order of operations, the two candidate sequences (first merged) K 7 after break K 3. First cut K 3 after combination K 7) All certificates failed. The system performed a split repair according to the fourth level: In O 2" combined K Insert a protection group switching operation before 7”, and R 7. Switch to the protection setting group that adapts to the reverse fault current direction, and execute the switch after confirming that the switch is completed. O 2; in O 3 breaks K 3. Insert a pre-adjustment operation beforehand, and include the condition that the absolute value of the measured communication power does not exceed the specified limit into the set of pre-permitted conditions. A 3. Executed from step five. O 3. Check each item one by one before proceeding. The split operation sequence is as follows: O 1 generator car in parallel → O 1.5 Switch R 7. Target protection setting group (readback confirmation) → O 2-in-1 K 7→ O 3 breaks K 3 (Pre-set Permission Set) A(The communication power limit conditions are already included in section 3) → O 4 breaks K 4. The system recalculates all certificates from step one for the split new sequence, confirming all intermediate states. This forms the final operation sequence.

[0130] Level 5 Repair: Determined as unexecutable.

[0131] If none of the above four-level repair schemes can restore all intermediate topology states If the value is restored to non-negative, the system outputs the conclusion that "this maintenance plan is not feasible under the current conditions" and suggests switching to power outage maintenance or other power supply methods.

[0132] For any of the above repair actions involving switching protection setting groups or adjusting the power bank's operating mode, it must be confirmed that the on-site execution has been completed and successfully read back before recalculating the certificate. After each repair, the system regenerates the certificates for all intermediate topology states starting from the first step, rather than just recalculating the certificates for the single failed state, to ensure global consistency.

[0133] like Figure 3 As shown, the system of the present invention includes an operation ticket parsing module, an intermediate topology expansion module, an interval fault calculation module, a protection coordination verification module, a certificate generation module, a repair action synthesis module, an operation barrier module, and a field readback module, with each module forming a complete data transmission link.

[0134] Construct a 10kV radial feeder. The minimum short-circuit capacity of the upstream power grid is 85MVA, and the maximum short-circuit capacity is 130MVA; a 1000kVA rated capacity synchronous generator is connected to the node. N 6. Secondly, transient reactance The voltage rating is 0.16–0.19 pu; the total capacity of the two photovoltaic grid-connected points is 600 kW; the inverter fault current limit is 1.10–1.25 times the rated current, and the duration is 80–160 ms; the power supply load is 520–880 kW.

[0135] The original operation sequence includes: O 1 generator car in parallel; O 2. Close the contact switch K 7; O 3. Disconnect the upstream switch in the maintenance area. K 3; O 4. Disconnect the downstream switch in the maintenance area. K 4. And form an isolated island; O 5. Perform maintenance; O 6 recovery K 3; O 7. Disconnect the generator car. The system is formed accordingly. G0 to G There are seven representative intermediate states in total. The protection configuration includes... K Three-way overcurrent main protection R 3. K 7-way overcurrent backup protection R 7. Overcurrent protection at the generator car outlet R g and zero-sequence grounding protection R 0.

[0136] Step 1 execution process: The system reads the above from the operation ticket. O 1 to O 7. With G Starting from 0, O 1. Change the generator car parallel switch from open to closed to generate power. G 1; O 2 K 7 is changed from a separate position to a combined position, generating G 2; O 3 generals K 3 is changed from a combined position to a separate position, generating G 3; O 4 generals K 4. Change from a combined position to a separate position, generating... G 4. Generate G Simultaneously with step 4, the system scans connectivity: K 3 and K All four positions are terminating, and the incoming line to the upstream power grid has been cut off; K Position 7 is the closed position, and the generator truck and two photovoltaic panels remain connected to the load area. Therefore, the effective power source set is {generator truck G1, PV1, PV2}.

[0137] The second step is... G Execution process for example, in an isolated state: Rated capacity of generator car Rated voltage Rated current Subtransient reactance range Substitute into formula (2-2): ; However, this value represents the subtransient short-circuit current at the generator outlet. After passing through the outlet transformer and line impedance, it flows through... R The current of 3 needs to be distributed in the network.

[0138] The interval short-circuit calculation is performed according to steps A through E: Step A: The system according to G A short-circuit computation network is established using the topology of 4. K 3 and K 4th percentile, KAt position 7, the upstream power grid is isolated. For two-phase short-circuit faults, a composite positive-sequence and negative-sequence network is established. The positive-sequence reactance of the generator car... Negative sequence reactance X 2. Zero-sequence reactance X 0 are respectively placed into the corresponding sequence network; two photovoltaics are placed into their grid-connected nodes as controlled current sources.

[0139] Step B: The system performs a full combination of all parameter endpoints. The upstream power grid is isolated and does not participate; generator truck... Take the two endpoints, 0.16 and 0.19, corresponding to... The contribution range is [30.4, 36.1]A; the photovoltaic current limiting factor is set to the two endpoints of 1.10 and 1.25; the fault resistance is set to a preset value. and There are two endpoints. A total of 2×2×2=8 sets of parameter combinations.

[0140] Step C: For each set of parameters, substitute the system into the two-phase short-circuit composite sequence network to solve for the flow path. R 3 and R 7. Fault current value and directional torque value.

[0141] Step D: Iterate through all 8 sets of calculation results and take the minimum value. , Take the maximum value The minimum value is selected from the set of directional torques. Step E: System Record The corresponding parameter combination is Photovoltaic current limiting 1.10 times, fault resistor ;Record I The parameter combination corresponding to +=1.06kA is: Photovoltaic current limiting 1.25 times, fault resistor .

[0142] The third step, taking grid-connected protection group A as an example, is as follows: In grid-connected protection group A R 3 startup value Substituting into formula (3-1), we get: . The certificate failed, and the reason for the failure was "insufficient sensitivity of the main protection".

[0143] The system switched to island temporary protection group B, in which : .

[0144] Sensitivity returned to a positive value. Continue calculating the load separation margin: Based on measurements taken 30 minutes before the operation and G 4. TrendsR Maximum operating current of line 3 ; Substituting into formula (3-2), where, .

[0145] The load separation is satisfied. However, we need to continue calculating the primary / backup selectivity: Main protection R 7 is for backup protection. The interval program calculates the action time at 0.79kA, 0.82kA, 1.03kA, 1.06kA, and the inflection point of the protection curve. The most unfavorable point is obtained. R 3. Action time: 0.31s R 7. Action time 0.46s, substituting into formula (3-3): .

[0146] Although the sensitivity issue was resolved, selectivity failed. Switching to protection group C resolved the issue. R The time factor was increased from 0.28 to 0.36, and the curve was checked again. R 7. The most unfavorable action time is 0.58s: .

[0147] At this point, all three core margins have been restored to non-negative.

[0148] Fourth step execution process: exist G 4. In isolated state, R The directional elements of system 7 must be able to withstand reverse fault current. The system calculates the directional torque under the most unfavorable source combination. Substituting into formula (4-1), we get: .

[0149] The directional element margin is satisfied.

[0150] For single-phase ground faults, the system calculates zero-sequence parameters. After the neutral point grounding resistor is activated, the single-phase ground fault at the remote end is minimized. The zero-sequence startup value is 50A. Substitute into formula (4-3): .

[0151] The grounding fault identification margin is met. If the grounding resistor is not in operation, the minimum is 3. I If 0 is reduced to 41A, then The certificate immediately failed. Therefore, "Grounding resistance is already in place" must be entered. Aj And then read back from step five.

[0152] Voltage margin Carrying capacity margin .

[0153] Calculate according to formula (4-4) . Generate certificate Π G 4. Specify protection group C. Recorded in the certificate. G 4. Equipment Status List ：K 3rd percentile, K 7 combined positions K 4. Still in position, and the identification of each protection setting group, etc.

[0154] Fifth step execution process: Reverse push-in The conditions that must be met beforehand (i.e.) AG 4): K 3rd percentile, K 7 combined positions K 4 remains in position; R 3 and R 7 has been switched to protection group C; grounding resistor is in operation (corresponding to...) constraint); R The current in the three branches is no greater than 0.40kA (corresponding to...). (Constraints); the minimum node voltage is not less than 0.93 pu (corresponding to...) M V Constraints); the generator car is in islanded voltage source preparation mode (corresponding to...). constraint).

[0155] operate Before execution, on-site verification confirms that all conditions are met before release. Execution license.

[0156] After the operation is completed, wait for confirmation from the dual-position contact and check if the actual switch status matches the certificate. G Recorded in 4 G 4. The device status list is consistent: quantile, Combination, The status indicator is checked for consistency; the protection group readback is still C; voltage and current are checked and found to be normal for three consecutive sampling cycles. After all confirmations are complete, the status pointer is moved from... Advance to .

[0157] The triggering conditions for step six: If certificate Π G 4 For example, under grid-connected protection group A =−0.177, first in Previously inserted protection group switching operation ,Will Switch to protection group B or C, read back for confirmation after the switch is complete, then recalculate all intermediate state certificates and confirm. of B Release only after the value is non-negative Execution license.

[0158] like Failure, in After inserting the "connect neutral point grounding resistor" operation, read back for confirmation before releasing it. O 4.

[0159] The characteristics of each intermediate state are summarized below:

[0160] 8. Sequence Restructuring After Certificate Failure In another operating condition, the operation sequence is as follows: Generator cars side by side, Broken , combine , Broken .

[0161] Generate the intermediate state according to the first step. G 1 (After the generator cars are paralleled), calculations show that if the original order is followed... (First break) In the intermediate state, only the generator car supplies power to the load, but Directional protection has not yet established reverse polarity. <0, certificate failed.

[0162] Try the second candidate sequence: Generator cars side by side, combine , O 3 breaks , O 4 breaks K 4. In G 2 (together) (Afterwards), short-term dual-path parallel supply leads to primary and backup selectivity If the value is less than 0, the certificate will also fail.

[0163] Perform the repair as per step six: [Incomplete] Previously inserted Switch to bidirectional protection group operation, and in the interruption Previously, the condition that the absolute value of the measured communication power does not exceed the specified limit was included in the set of prerequisite allowable conditions. A3. After inserting two preconditions, the two candidate sequences... and All are restored to non-negative. Select the optimal sequence and recalculate all certificates from the first step, confirming all intermediate states. The final operation ticket is generated after the value is ≥0.

[0164] IX. Parametric Monte Carlo Simulation Verification To verify the effectiveness of the technical chain of this invention, 500 sets of operating conditions were generated using a reproducible parametric Monte Carlo model. Random variables included: photovoltaic fault current limiting multiple (1.05–1.35 times), load factor (0.5–1.2 times rated load), transient contribution factor of generator trip (0.85–1.15 times the baseline value), protection communication / exit delay (±20ms), and measurement error (±3%). The fixed random seed was 20260729. Seven intermediate states were calculated for each set of operating conditions. and form with the minimum value .

[0165] Figure 4 The distribution of operational barriers in each intermediate state is shown, and the islanded state is also shown in the figure. G 4. G 5) A negative barrier may occur under certain parameter combinations because the minimum fault current decreases in islanded state and compresses the primary / backup time difference—this risk cannot be detected by simply checking the final state power flow, but the state-by-state certificate of this invention can pinpoint the risk to the point where the fault occurs. G 4. Protection groups and grounding methods prior to this. Figure 5 The minimum fault current range and the 1.5 times starting current requirement are placed on the same coordinate system. Further repair is triggered when the 5th percentile value in any state is lower than the sensitivity requirement.

[0166] The simulation results are as follows:

[0167] Figure 6 The coverage comparison of three verification strategies is shown. This scheme achieves a 100% recognition rate for unsafe intermediate states, far exceeding that of final-state verification only (19.0%) and state-by-state power flow verification (48.0%). While the computation time of this scheme increases to the order of hundreds of milliseconds, this calculation is performed before operation ticket rehearsals and each operation, still providing ample margin relative to on-site operation time (seconds to minutes). More importantly, the identification targets expand from voltage / overload to identifiable failures of protection systems, overstepping of protection levels, directional mismatch, and ground faults, representing a different technical effect from ordinary power flow verification. The above data comes from a parametric model and is used to verify the effectiveness of the technical chain, not to claim real-world performance.

[0168] Therefore, this embodiment can be deployed in a distribution automation master station, a protection setting management system, or a field edge controller, such as... Figure 3 As shown, through the collaborative work of the operation ticket parsing module, intermediate topology expansion module, interval fault calculation module, protection coordination verification module, certificate generation module, repair action synthesis module, operation barrier module and field readback module, data interaction is achieved with the operation ticket system, distribution automation master station, protection setting management system and field controller.

[0169] It should be noted that the deployment location of the operational barrier is not limited to the field controller; it can also be deployed in the distribution automation master station or protection setting management system, issuing permission / locking commands to the field controller via remote communication. All of the above deployment methods fall within the scope of the industrial applicability of this invention.

[0170] This invention is applicable to uninterrupted power supply maintenance scenarios in medium-voltage distribution networks that include mobile generators and distributed photovoltaic systems, and has clear industrial applicability.

[0171] Secondly, this embodiment also provides a medium-voltage distribution network uninterrupted maintenance sequence control system, which includes: The operation ticket parsing module is used to parse maintenance operation tickets and obtain an operation set consisting of multiple operations in sequence; The intermediate topology expansion module is used to apply each operation to the primary device model one by one according to the order of the operation set, starting from the initial topology state confirmed on site, to generate a series of intermediate topology states. The latter intermediate topology state is obtained by transferring the former intermediate topology state through the current operation. At the same time as generating each intermediate topology state, the effective power supply set in that state is determined. The fault contribution modeling module is used to establish a fault contribution model for each effective power source in each intermediate topology state, thereby obtaining the lower limit and upper limit of the fault current flowing through each protection device in the intermediate topology state. The hard margin calculation module is used to calculate the set of hard margins for each protection device in the intermediate topology state based on the lower limit value and the upper limit value of the fault current. The set of hard margins includes at least: the sensitivity margin of the main protection determined by the minimum fault current and the protection start value, the selectivity margin determined by the time difference between the main protection and the backup protection, and the load separation margin determined by the protection start value and the maximum operating current. The certificate generation module is used to take the minimum value in the set of hard margins as the operation barrier value of the intermediate topology state. If the operation barrier value is not less than zero, a protection identifiability certificate for the intermediate topology state is generated. The certificate includes at least the applicable protection setting group and the set of prerequisite allowable conditions that must be met before entering the intermediate topology state. The operation barrier module is used to read the field measured data and verify it with the certificate before executing the current operation. The execution permission of the current operation is released only when the current setting group read back by the field protection device is consistent with the applicable protection setting group specified in the certificate, the measured electrical quantity is within the range of the pre-permitted condition set, and the operation barrier value is not less than zero. The repair module is used to perform a repair action before executing the current operation when the operation barrier value is less than zero, and to re-trigger the intermediate topology expansion module, the fault contribution modeling module, the hard margin calculation module, and the certificate generation module after the repair to recalculate the certificates of all intermediate topology states; the repair action includes at least one of switching temporary protection setting groups, adjusting the mobile power supply fault current limiting mode, or rewriting the operation sequence; if there are still intermediate topology states with operation barrier values ​​less than zero after the repair, it is determined that the operation sequence cannot be executed under the current conditions.

[0172] In the description of this invention, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. "A plurality of" means two or more, unless otherwise explicitly specified.

[0173] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0174] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "over," and "on top" of the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0175] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Furthermore, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0176] Any process or method description in the flowchart or otherwise herein can be understood as representing a module, segment, or portion of code comprising one or more executable instructions for implementing a particular logical function or process, and the scope of the preferred embodiments of the invention includes additional implementations in which functions may be performed not in the order shown or discussed, including substantially simultaneously or in reverse order depending on the functions involved, as will be understood by those skilled in the art to which embodiments of the invention pertain.

[0177] Therefore, this embodiment discloses a computer device.

[0178] The computer device includes a processor, a memory, and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, it implements the steps described in the above-described embodiment of a method for uninterrupted maintenance sequence control of a medium-voltage distribution network. Alternatively, when the processor executes the computer program, it implements the functions of each module / unit in the above-described system embodiments.

[0179] For example, the computer program can be divided into one or more modules / units, which are stored in the memory and executed by the processor to complete the present invention. The one or more modules / units can be a series of computer program instruction segments capable of performing specific functions, which describe the execution process of the computer program in the medium-voltage distribution network uninterrupted maintenance sequence control method.

[0180] The computer device may be a desktop computer, laptop, handheld computer, or cloud server, etc. The computer device may include, but is not limited to, a processor and memory.

[0181] The logic and / or steps represented in the flowchart or otherwise described herein, for example, can be considered as a ordered list of executable instructions for implementing logical functions, and can be embodied in any computer-readable medium for use by, or in conjunction with, an instruction execution system, apparatus, or device (such as a computer-based system, a processor-included system, or other system that can fetch and execute instructions from, an instruction execution system, apparatus, or device). For the purposes of this specification, "computer-readable medium" can be any means that can contain, store, communicate, propagate, or transmit programs for use by, or in conjunction with, an instruction execution system, apparatus, or device. More specific examples (a non-exhaustive list) of computer-readable media include: an electrical connection having one or more wires (electronic device), a portable computer disk drive (magnetic device), random access memory (RAM), read-only memory (ROM), erasable and editable read-only memory (EPROM or flash memory), fiber optic devices, and portable optical disc read-only memory (CDROM). Alternatively, the computer-readable medium may be paper or other suitable media on which the program can be printed, since the program can be obtained electronically, for example, by optically scanning the paper or other medium, followed by editing, interpreting, or otherwise processing as necessary, and then stored in a computer memory.

[0182] It should be understood that various parts of the present invention can be implemented in hardware, software, firmware, or a combination thereof. In the above embodiments, multiple steps or methods can be implemented in software or firmware stored in memory and executed by a suitable instruction execution system. For example, if implemented in hardware, as in another embodiment, it can be implemented using any one or a combination of the following techniques known in the art: discrete logic circuits having logic gates for implementing logical functions on data signals, application-specific integrated circuits (ASICs) having suitable combinational logic gates, programmable gate arrays (PGAs), field-programmable gate arrays (FPGAs), etc.

[0183] Those skilled in the art will understand that all or part of the steps of the methods in the above embodiments can be implemented by a program instructing related hardware. The program can be stored in a computer-readable storage medium, and when executed, the program includes one or a combination of the steps of the method embodiments.

[0184] Furthermore, the functional units in the various embodiments of the present invention can be integrated into a processing module, or each unit can exist physically separately, or two or more units can be integrated into a module. The integrated module can be implemented in hardware or as a software functional module. If the integrated module is implemented as a software functional module and sold or used as an independent product, it can also be stored in a computer-readable storage medium.

[0185] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A sequence control method for uninterrupted maintenance of medium-voltage distribution networks, characterized in that, Includes the following steps: S1 analyzes the maintenance operation ticket and obtains an operation set consisting of multiple operations in sequence. Starting from the initial topology state confirmed on-site, and following the order of the operation set, each operation generates a series of intermediate topology states, wherein the next intermediate topology state is obtained by transferring the previous intermediate topology state through the current operation. At the same time as generating each intermediate topology state, the effective power supply set in that state is determined. S2 establishes a fault contribution model for each effective power source in each intermediate topology state, and then obtains the lower limit and upper limit of the fault current flowing through each protection device in the intermediate topology state. S3 calculates the set of hard margins for each protection device in this intermediate topology state based on the lower limit and upper limit of the fault current. The set of hard margins includes at least: the sensitivity margin of the main protection determined by the minimum fault current and the protection start value; the selectivity margin determined by the time difference between the main protection and the backup protection; and the load separation margin determined by the protection start value and the maximum operating current. S4 takes the minimum value in the set of hard margins as the operation barrier value of the intermediate topology state; if the operation barrier value is not less than zero, a protection identifiability certificate for the intermediate topology state is generated, and the certificate includes at least the applicable protection setting group and the set of prerequisite allowable conditions that must be met before entering the intermediate topology state. Before executing the current operation, S5 reads the field measured data and checks it against the certificate. Only when the current set value group read back by the field protection device is consistent with the applicable protection set value group specified in the certificate, the measured electrical quantity is within the range of the pre-permitted condition set, and the operation barrier value is not less than zero, will the execution permission for the current operation be released. S6 If the operation barrier value is less than zero, a repair action is performed before the current operation is executed, and after the repair, the certificates of all intermediate topology states are recalculated starting from step S1. The repair action includes at least one of switching the temporary protection setting group, adjusting the mobile power supply fault current limiting mode, or rewriting the operation sequence. If there are still intermediate topology states with an operation barrier value less than zero after the repair, the operation sequence is determined to be unexecutable under the current conditions.

2. The method for uninterrupted maintenance sequence control of medium-voltage distribution networks according to claim 1, characterized in that, The operation items in the operation set include: device identifier, which is a unique ID of a specific operation object; initial state, which is the separate or combined position that the device should be in before executing the operation; target state, which is the separate / combined position that the device should reach after executing the operation; operation type, which is the allowed operation mode; and pre- and post-operations dependencies, which indicate the dependencies that the operation must be executed only after the completion of the preceding operations. The generation of a series of intermediate topological states is represented as follows: ; Where T is the primary device state transition operator. For the operation items in the operation set, Before execution j -1 represents the intermediate topological state after an operation, where J is the total number of operations in the operation set.

3. The method for uninterrupted maintenance sequence control of medium-voltage distribution networks according to claim 2, characterized in that, The process of constructing the fault contribution model includes: For each intermediate topology state and each preset fault type, short-circuit calculation is performed based on the parameter range of each power source in the effective power source set under that intermediate topology state. The parameter range includes the Thevenin equivalent impedance range converted from the short-circuit capacity range of the upper-level power grid, the subtransient parameter range of the mobile power source, and the fault current limiting range of the inverter-type distributed power source. The fault current boundary contributed by the upper-level power grid is determined based on the Thevenin equivalent impedance range of the upper-level power grid. The fault current contribution range of the mobile power supply is calculated, which is obtained through the subtransient parameter range of the mobile power supply: ； in, For the subtransient fault current of the mobile power supply, This is the rated line voltage of the power bank. This is the maximum value of the subtransient reactance, used to calculate the minimum fault current contribution. This is the minimum value of the subtransient reactance, used to calculate the contribution of the maximum fault current; The fault current limiting range of the inverter-type distributed power source is defined as follows: ； in, This refers to the fault current of an inverter-type distributed power source. This is the lower limit of the fault current limiting factor; This is the upper limit of the fault current limiting factor; This is the rated current of the inverter-type distributed power source.

4. The method for uninterrupted maintenance sequence control of medium-voltage distribution networks according to claim 3, characterized in that, The process of obtaining the lower limit and upper limit of the fault current flowing through each protection device in this intermediate topology state includes: Based on the current intermediate topology and the current fault type, establish the corresponding short-circuit calculation network; for three-phase short-circuit faults, establish a positive sequence network; for two-phase short-circuit faults, establish a positive sequence and negative sequence composite network; for single-phase ground faults and two-phase ground faults, establish a positive sequence, negative sequence and zero sequence composite network. The endpoint values ​​of the Thevenin equivalent impedance range of the upper-level power grid, the endpoint values ​​of the fault current contribution range of the mobile power supply, the endpoint values ​​of the fault current contribution range of the inverter-type distributed power supply, and the endpoint values ​​of the preset fault resistance range are combined to form multiple sets of parameter combinations. Substitute each set of parameters into the short-circuit calculation network to solve for the fault current value flowing through each protection device under each set of parameters. The minimum value among all calculation results is taken as the lower limit of the fault current, and the maximum value is taken as the upper limit of the fault current.

5. The method for uninterrupted maintenance sequence control of medium-voltage distribution networks according to claim 4, characterized in that, The step of calculating the hard margin set of each protection device in this intermediate topology state based on the lower limit and upper limit of the fault current includes: The sensitivity margin of the main protection, which is determined by the lower limit of the fault current and the protection start value, is expressed as: ； in, In the intermediate topology state Below, regarding fault types f Flow through protection device r The lower limit of the fault current, For protection devices r In state The starting current used below; The minimum sensitivity coefficient specified; The load separation margin, determined by the protection start value and the maximum operating current, is expressed as: ； in, To protect against starting current; To account for the reliability coefficient of the motor's self-starting and measurement errors; The maximum load current flowing through the branch where the protection device r is located, formed in the operating boundary interval U under state Gⱼ; The selectivity margin between primary and backup protection is determined by the time difference between the actions of the primary and backup protection, and is expressed as: ； in, For fault current variables, In the intermediate topology state Below, regarding fault types f lower limit of fault current ， In the intermediate topology state Below, regarding fault types f The upper limit of the fault current; The operating time of the backup protection under fault current I; The operating time of the main protection under fault current I; To minimize the coordination level difference, it includes the operating time error of backup protection, circuit breaker tripping time, protection return time, and safety margin.

6. The method for uninterrupted maintenance sequence control of medium-voltage distribution networks according to claim 5, characterized in that, The protection identifiability certificate for generating this intermediate topology state includes: The minimum value in the set of hard margins is taken as the intermediate topological state. Operational barrier value , is represented as: ； in, To operate on the barrier value, the subscript j Number the intermediate topology states; and These are the main protection sensitivity margin, load separation margin, main backup selectivity margin, directional element margin, and ground fault identification margin. Normalized reference value for primary protection sensitivity margin The normalized baseline value for load separation margin To minimize the fit grade difference, Normalized reference value for orientation element margin; The normalized margin for the hard constraint on node voltage. Normalized margin for hard constraints on branch current; like If the value is ≥ 0, a protection identifiability certificate is generated for this state. The protection identifiability certificate includes: the applicable protection setting group identifier. and entering intermediate topology state The set of prerequisite conditions that must be met The set of prerequisite allowable conditions Derived from the margin constraint that minimizes the operational barrier value during certificate generation, it at least includes the measured electrical boundary and state conditions that must be satisfied before entering this intermediate topology state, and the applicable protection setting group identifier. This is an identifier for the set value combination that each protection device must use in the current intermediate topology state.

7. The method for uninterrupted maintenance sequence control of medium-voltage distribution networks according to claim 6, characterized in that, The step of performing a repair action before performing the current operation includes: The switching of the temporary protection setting group includes: selecting the target protection setting group from the pre-configured backup protection setting group, sending a switching command to the field protection device through the communication interface, switching the current setting group to the target protection setting group, reading back to confirm that the switching is completed, synchronously recalculating all margins related to the protection start current, and regenerating the certificates of all intermediate topology states. The adjustment of the mobile power bank fault current limiting mode includes: reading the current mode number through the communication interface, switching it to the target mode number according to the reason for the certificate failure, and after the switching is completed, reading back to confirm that the mode switching is successful, and recalculating the full sequence certificate from the beginning. The rewriting operation sequence includes: identifying adjacent operation pairs in the current operation sequence where two operation objects have no direct electrical dependency and the power supply set and effective short-circuit path do not change after the exchange of any intermediate state; exchanging their execution order; generating a new candidate operation sequence; and restarting the expansion of all intermediate topology states and recalculating the certificates of each state.

8. The method for uninterrupted maintenance sequence control of medium-voltage distribution networks according to claim 7, characterized in that, The method also includes: When the rewrite operation sequence cannot resolve all certificate failures, the original single operation is broken down into multiple steps, with protection group switching or status confirmation steps inserted between each step. The broken-down operation includes: Identify the operations that caused the certificate to fail. And the reasons for its failure, in Insert one or more pre-operations, including at least one of switching protection setting groups, connecting the grounding device, or adjusting the operating mode of the mobile power supply, and read back to confirm that the pre-operations have been completed before executing the original operation. The state conditions corresponding to the pre-operation to be inserted are recorded in the set of pre-allowed conditions for this intermediate state. Before performing the procedure on-site again, each item must be checked.

9. A control system based on the uninterrupted power supply maintenance sequence control method for medium-voltage distribution networks according to any one of claims 1-8, characterized in that, The system includes: The operation ticket parsing module is used to parse maintenance operation tickets and obtain an operation set consisting of multiple operations in sequence; The intermediate topology expansion module is used to apply each operation to the primary device model one by one according to the order of the operation set, starting from the initial topology state confirmed on site, to generate a series of intermediate topology states. The latter intermediate topology state is obtained by transferring the former intermediate topology state through the current operation. At the same time as generating each intermediate topology state, the effective power supply set in that state is determined. The fault contribution modeling module is used to establish a fault contribution model for each effective power source in each intermediate topology state, thereby obtaining the lower limit and upper limit of the fault current flowing through each protection device in the intermediate topology state. The hard margin calculation module is used to calculate the set of hard margins for each protection device in the intermediate topology state based on the lower limit value and the upper limit value of the fault current. The set of hard margins includes at least: the sensitivity margin of the main protection determined by the minimum fault current and the protection start value, the selectivity margin determined by the time difference between the main protection and the backup protection, and the load separation margin determined by the protection start value and the maximum operating current. The certificate generation module is used to take the minimum value in the set of hard margins as the operation barrier value of the intermediate topology state. If the operation barrier value is not less than zero, a protection identifiability certificate for the intermediate topology state is generated. The certificate includes at least the applicable protection setting group and the set of prerequisite allowable conditions that must be met before entering the intermediate topology state. The operation barrier module is used to read the field measured data and verify it with the certificate before executing the current operation. The execution permission of the current operation is released only when the current setting group read back by the field protection device is consistent with the applicable protection setting group specified in the certificate, the measured electrical quantity is within the range of the pre-permitted condition set, and the operation barrier value is not less than zero. The repair module is used to perform a repair action before executing the current operation when the operation barrier value is less than zero, and to re-trigger the intermediate topology expansion module, the fault contribution modeling module, the hard margin calculation module, and the certificate generation module after the repair to recalculate the certificates of all intermediate topology states; the repair action includes at least one of switching temporary protection setting groups, adjusting the mobile power supply fault current limiting mode, or rewriting the operation sequence; if there are still intermediate topology states with operation barrier values ​​less than zero after the repair, it is determined that the operation sequence cannot be executed under the current conditions.

10. A computer device, characterized in that, include: One or more processors; The processor is used to store one or more programs; When the one or more programs are executed by the one or more processors, the steps of the medium-voltage distribution network uninterrupted maintenance sequence control method as described in any one of claims 1 to 8 are implemented.

11. A computer-readable storage medium, characterized in that, It contains a computer program, which, when executed, implements the steps of the medium-voltage distribution network uninterrupted maintenance sequence control method as described in any one of claims 1 to 8.

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