N-1 Key Fault Screening Method and System for Guaranteed Power Grid
By applying the concentric relaxation principle and key analysis methods in the guaranteed power grid, the problems of manual screening dependence and unreliability in the existing technology are solved, and the rapid, dynamic and scientific screening of key N-1 faults is achieved, which improves the stability and power supply reliability of the power grid.
Patent Information
- Application Number
- CN202211003299.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2022-08-19
- Publication Date
- 2025-06-17
- Estimated Expiration
- 2042-08-19
AI Technical Summary
In the prior art, the N-1 key fault screening method for guaranteed power grids relies on manual screening, and there is a problem that it is subjective, has low reliability and cannot achieve rapid and dynamic updates.
The N-1 fault screening method based on the principle of concentric relaxation is adopted. By performing N-1 fault scanning on the guaranteed power grid, the correlation matrix of each fault and the system is determined, and the key matrix of the N-1 fault of the guaranteed power grid is calculated based on the critical analysis of the generator, transformer and connection line, and the critical matrix of the N-1 fault of the guaranteed power grid is calculated to achieve rapid screening of the N-1 critical faults.
The rapid, dynamic and objective and scientific screening of N-1 key faults of the guaranteed power grid is achieved, the reliability and real-time of the method are improved, and the expected accident set of the guaranteed power grid can be effectively and dynamically adjusted.
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Figure CN115408658B_ABST
Abstract
Description
Technical Field
[0001] The present invention belongs to the field of electrical automation, and particularly relates to an N-1 key fault screening method and system for a guaranteed power grid. Background Art
[0002] With the development of economic technology and the improvement of people's living standards, electric energy has become an essential secondary energy source in people's production and life, bringing endless convenience to people's production and life. Therefore, ensuring the stable and reliable supply of electric energy has become one of the most important tasks of the power system.
[0003] Currently, with the frequent occurrence of extreme weather, the power grid system has begun to gradually build a guaranteed power grid for ice area cities to ensure that, under extreme climate conditions, important lines above 110 kV do not collapse, thereby ensuring the safe power supply of important users related to people's livelihood and users, and minimizing the impact of ice disasters on the safety of the power grid and power supply.
[0004] Under extreme conditions, the guaranteed power grid composed of important substations, key lines, and disaster-resistant guarantee power sources as the backbone grid of the power grid needs to meet the continuous and reliable power supply of core users such as urban command (emergency) agencies and core infrastructure under extreme conditions. The N-1 principle requires that in the guaranteed power grid system under normal operating conditions, when any component (such as a line, generator, transformer, etc.) fails or is disconnected due to a fault, the power system should be able to maintain stable operation and normal power supply, and other components should not be overloaded, and the voltage and frequency are within the allowable range. Due to the reliability limitations of the guaranteed power grid itself, it is required to quickly screen N-1 key faults, so as to dynamically adjust the contingency set of the guaranteed power grid.
[0005] However, the current N-1 key fault screening method for the guaranteed power grid generally relies on the method of expert manual screening; however, this manual screening method not only highly depends on the experience and personal skills of the screening experts, has a large subjectivity and low reliability, but also cannot achieve fast and dynamic updates. Summary of the Invention
[0006] One of the purposes of the present invention is to provide an N-1 key fault screening method for a guaranteed power grid with high reliability, good real-time performance, and objective science.
[0007] Another purpose of the present invention is to provide a system for implementing the N-1 key fault screening method for the guaranteed power grid.
[0008] The N-1 key fault screening method for the guaranteed power grid provided by the present invention includes the following steps:
[0009] S1. Determine the guaranteed power grid corresponding to the target power grid, and obtain the parameter data of the guaranteed power grid;
[0010] S2. Conduct an N-1 fault scan on the guaranteed power grid to obtain the N-1 fault set, and determine the incidence matrix of each fault in the fault set with the system based on the concentric relaxation principle;
[0011] S3. Conduct a criticality analysis on the generators in the guaranteed power grid according to their capacity and voltage level to obtain the generator criticality weight matrix of each generator;
[0012] S4. Conduct a criticality analysis on the transformers in the guaranteed power grid according to their capacity, voltage level and the state of accessing the power grid to obtain the transformer criticality weight matrix of each transformer;
[0013] S5. Conduct a criticality analysis on the tie lines in the guaranteed power grid according to the topological structure and voltage level of the transmission lines to obtain the tie line criticality weight matrix of each tie line;
[0014] S6. Calculate the criticality matrix of the N-1 faults of the guaranteed power grid based on the matrices obtained in steps S2 to S5, and complete the screening of the N-1 critical faults of the guaranteed power grid according to the criticality matrix.
[0015] The obtaining of the parameter data of the guaranteed power grid described in step S1 specifically includes the following steps:
[0016] Determine the operation mode of the guaranteed power grid, and determine the important stations, key lines and guaranteed power sources according to the power grid plan;
[0017] Obtain the generator set in the guaranteed power grid as the transformer set as the tie line set as where G i is the i-th generator, n G is the number of generators, T i is the i-th transformer, n T is the number of transformers, L i is the i-th tie line, n L is the number of tie lines.
[0018] The conducting of an N-1 fault scan on the guaranteed power grid to obtain the N-1 fault set, and determining the incidence matrix of each fault in the fault set with the system based on the concentric relaxation principle described in step S2 specifically includes the following steps:
[0019] Obtain the N-1 fault set as S = {ρ|ρ∈S G or ρ∈S T or ρ∈S L}, ρ is an element in the N-1 fault set; ρ∈S G indicates that the fault belongs to a generator fault, ρ∈S TIt indicates that the fault belongs to the transformer fault, and ρ ∈ S L It indicates that the fault belongs to the tie line fault;
[0020] Calculate the electrical distance d between any two nodes i and j in the guaranteed power grid ij :
[0021] d ij = z ii + z jj - z ij - z ji
[0022] In the formula, z ii is the self - impedance of node i; z jj is the self - impedance of node j; z ij is the mutual impedance between node i and node j; z ji is the mutual impedance between node j and node i;
[0023] Construct the incidence matrix C as:
[0024]
[0025] In the formula, n = n G + n T + n L , n G is the number of generators, n T is the number of transformers, n L is the number of tie lines; the element c ij represents the connection relationship between node i and node j, and the value is i = 1, 2,..., n, j = 1, 2,..., n.
[0026] The criticality analysis of the generators in the guaranteed power grid according to the capacity and voltage level described in step S3 to obtain the generator criticality weight matrix of each generator specifically includes the following steps:
[0027] Calculate the criticality value W of the m - th generator using the following formula gm :
[0028]
[0029] In the formula, S gm is the rated capacity of the m - th generator; U gm is the rated voltage of the m - th generator; U gmin is the minimum rated voltage among all generators; S gt is the rated capacity of the t - th generator; n G is the number of generators; U gmaxis the maximum rated voltage among all generators; m = 1, 2,..., n G , t = 1, 2,..., n G ;
[0030] According to the criticality values of each generator, the generator criticality weight matrix is obtained as
[0031] Step S4 conducts a criticality analysis on the transformers in the backup power grid according to the capacity, voltage level, and grid connection status, and obtains the transformer criticality weight matrix of each transformer, which specifically includes the following steps:
[0032] The criticality value W of the p-th transformer is calculated using the following formula tp :
[0033]
[0034] In the formula, F tp is the grid connection status variable of the p-th transformer, and if the p-th transformer is connected to the grid, then F tp = 1, if the p-th transformer is not connected to the grid, then F tp = 0; P tp is the rated capacity of the p-th transformer; U tp is the rated voltage of the p-th transformer; U tmin is the minimum rated voltage among all transformers; U tmax is the maximum rated voltage among all transformers; P th is the rated capacity of the h-th transformer; n T is the number of transformers; p = 1, 2,..., n T , h = 1, 2,..., n T ;
[0035] According to the criticality values of each transformer, the transformer criticality weight matrix is obtained as
[0036] Step S5 conducts a criticality analysis on the tie lines in the backup power grid according to the topological structure and voltage level of the transmission lines, and obtains the tie line criticality weight matrix of each tie line, which specifically includes the following steps:
[0037] The criticality value W of the q-th tie line is calculated using the following formula lp :
[0038]
[0039] In the formula, n lq is the number of nodes connected by the q-th tie line; n T is the number of transformers; nG is the number of generators; U lq is the rated voltage of the q-th tie line; U lmin is the minimum rated voltage among all tie lines; U lmax is the maximum rated voltage among all tie lines;
[0040] According to the criticality values of each tie line, the tie line criticality weight matrix is obtained as
[0041] The matrix obtained according to steps S2 - S5 in step S6 is calculated to obtain the criticality matrix of the N - 1 faults of the guaranteed power grid, and the N - 1 critical fault screening of the guaranteed power grid is completed according to the criticality matrix. The specific steps are as follows:
[0042] Construct the intermediate criticality matrix W as where W G is the generator criticality weight matrix; W T is the transformer criticality weight matrix; W L is the tie line criticality weight matrix;
[0043] The criticality matrix K of the N - 1 faults of the guaranteed power grid is calculated as K = CW, where C is the incidence matrix;
[0044] The criticality matrix K is expanded to obtain where K i is the criticality index of the i-th fault, and the larger the value of K i , the more serious the i-th fault is.
[0045] The present invention also provides a system for implementing the N-1 critical fault screening method for the guaranteed power grid, which specifically includes a data acquisition module, an incidence matrix calculation module, a generator criticality weight matrix calculation module, a transformer criticality weight matrix calculation module, a tie-line criticality weight matrix calculation module, and an N-1 critical fault screening module; the output end of the data acquisition module is simultaneously connected to the input ends of the incidence matrix calculation module, the generator criticality weight matrix calculation module, the transformer criticality weight matrix calculation module, and the tie-line criticality weight matrix calculation module; the output ends of the incidence matrix calculation module, the generator criticality weight matrix calculation module, the transformer criticality weight matrix calculation module, and the tie-line criticality weight matrix calculation module are simultaneously connected to the N-1 critical fault screening module; the data acquisition module is used to acquire the parameter data of the guaranteed power grid and upload the data to the incidence matrix calculation module, the generator criticality weight matrix calculation module, the transformer criticality weight matrix calculation module, and the tie-line criticality weight matrix calculation module; the incidence matrix calculation module is used to perform N-1 fault scanning on the guaranteed power grid to obtain an N-1 fault set, determine the incidence matrix of each fault in the fault set with the system based on the concentric relaxation principle, and upload the incidence matrix to the N-1 critical fault screening module; the generator criticality weight matrix calculation module is used to perform criticality analysis on the generators in the guaranteed power grid according to the capacity and voltage level to obtain the generator criticality weight matrix of each generator, and upload the result to the N-1 critical fault screening module; the transformer criticality weight matrix calculation module is used to perform criticality analysis on the transformers in the guaranteed power grid according to the capacity, voltage level, and the state of accessing the power grid to obtain the transformer criticality weight matrix of each transformer, and upload the result to the N-1 critical fault screening module; the tie-line criticality weight matrix calculation module is used to perform criticality analysis on the tie-lines in the guaranteed power grid according to the topological structure and voltage level of the transmission lines to obtain the tie-line criticality weight matrix of each tie-line, and upload the result to the N-1 critical fault screening module; the N-1 critical fault screening module is used to calculate the criticality matrix of the N-1 faults of the guaranteed power grid according to the received data information, and complete the N-1 critical fault screening of the guaranteed power grid according to the criticality matrix.
[0046] The N-1 critical fault screening method and system for the guaranteed power grid provided by the present invention, the proposed N-1 fault screening method based on the concentric relaxation principle is used for the rapid screening of N-1 critical faults of the guaranteed power grid, can evaluate and sort a large number of contingency fault sets, can quickly screen out a small number of critical faults that have a greater impact on the stability of the guaranteed power grid according to specific applications, and has high reliability, good real-time performance, and is objective and scientific. BRIEF DESCRIPTION OF THE DRAWINGS
[0047] Figure 1 It is a schematic flow chart of the method of the present invention.
[0048] Figure 2 Schematic diagram of the concentric relaxation principle in the method of the present invention.
[0049] Figure 3 Schematic diagram of the system structure of the 3-machine 9-node system in the embodiment of the method of the present invention.
[0050] Figure 4 Schematic diagram of the functional modules of the system of the present invention. Detailed implementation manners
[0051] As Figure 1 shown in the following is the schematic diagram of the method flow of the method of the present invention: The N-1 key fault screening method for the guaranteed power grid provided by the present invention includes the following steps:
[0052] S1. Determine the guaranteed power grid corresponding to the target power grid, and obtain the parameter data of the guaranteed power grid; determine the operation mode of the guaranteed power grid, and determine the important stations, key lines, and guaranteed power sources according to the power grid plan;
[0053] Obtain the generator set in the guaranteed power grid as the transformer set as the tie line set as where G i is the i-th generator, n G is the number of generators, T i is the i-th transformer, n T is the number of transformers, L i is the i-th tie line, n L is the number of tie lines;
[0054] S2. Conduct an N-1 fault scan on the guaranteed power grid to obtain an N-1 fault set, and determine the incidence matrix of each fault in the fault set and the system based on the concentric relaxation principle;
[0055] Specifically, it includes the following steps:
[0056] Obtain the N-1 fault set as S = {ρ|ρ ∈ S G or ρ ∈ S T or ρ ∈ S L}, ρ is an element in the N-1 fault set; ρ ∈ S G indicates that the fault belongs to a generator fault, ρ ∈ S T indicates that the fault belongs to a transformer fault, ρ ∈ S L indicates that the fault belongs to a tie line fault;
[0057] The concentric relaxation principle measures the electrical connection tightness between nodes through electrical distance; the smaller the electrical distance between two nodes, the closer the electrical connection between the two nodes. When a fault occurs at one node, the other node will be greatly affected; conversely, it indicates that the electrical connection between the two nodes is looser, and when a fault occurs at one node, the other node will be less affected. The schematic diagram of the concentric relaxation principle is as shown in Figure 2 Figure, where i, j, and k in the figure represent three nodes respectively, i = 1, 2,..., n; j = 1, 2,..., n; k = 1, 2,..., n; n = n G +n T +n L . d ij represents the electrical distance between node i and node j, and d ik represents the electrical distance between node i and node k. Since the electrical distance d ij is less than d ik , if the weights of node j and node k are the same, then the impact of a fault at node j on node i is greater than the impact of a fault at node k on node i; in the calculated guaranteed power grid, the electrical distance d ij between any two nodes i and j is calculated as follows:
[0058] d ij = z ii + z jj - z ij - z ji
[0059] In the formula, z ii is the self-impedance of node i, and numerically it is equal to the voltage of node i when a unit current is injected at node i and all other nodes are open; z jj is the self-impedance of node j, and numerically it is equal to the voltage of node j when a unit current is injected at node j and all other nodes are open; z ij is the mutual impedance between node i and node j; z ji is the mutual impedance between node j and node i; the mutual impedance is numerically equal to the voltage of node i or node j when a unit current is injected from node i or node j and all other nodes are open;
[0060] The incidence matrix C is constructed as:
[0061]
[0062] In the formula, n = n G + n T + n L , n G is the number of generators, n T is the number of transformers, n L is the number of tie lines; the element c ijIndicates the connection relationship between node i and node j, and the value is i = 1, 2, ..., n, j = 1, 2, ..., n;
[0063] In addition, to determine the criticality of each fault, in addition to being related to the connection relationship between the fault node and other nodes, it is also related to the weight of each node; taking Figure 2 the two nodes i and j shown as an example, if the weights of node i and node j are the same, since node i has another connected node k, then the criticality of node i failing is greater than the criticality of node j failing;
[0064] S3. According to the capacity and voltage level, conduct a criticality analysis of the generators in the guaranteed power grid to obtain the generator criticality weight matrix of each generator; specifically, it includes the following steps:
[0065] Calculate the criticality value W of the m-th generator using the following formula gm :
[0066]
[0067] In the formula, S gm is the rated capacity of the m-th generator; U gm is the rated voltage of the m-th generator; U gmin is the minimum rated voltage among all generators; S gt is the rated capacity of the t-th generator; n G is the number of generators; U gmax is the maximum rated voltage among all generators; m = 1, 2, ..., n G , t = 1, 2, ..., n G ;
[0068] According to the criticality values of each generator, the generator criticality weight matrix is
[0069] S4. According to the capacity, voltage level and the state of connecting to the power grid, conduct a criticality analysis of the transformers in the guaranteed power grid to obtain the transformer criticality weight matrix of each transformer; specifically, it includes the following steps:
[0070] Calculate the criticality value W of the p-th transformer using the following formula tp :
[0071]
[0072] In the formula, F tp is the state variable of the p-th transformer connecting to the power grid, and if the p-th transformer is connected to the power grid, then F tp= 1. If the p-th transformer is not connected to the power grid, then F tp = 0; P tp is the rated capacity of the p-th transformer; U tp is the rated voltage of the p-th transformer; U tmin is the minimum rated voltage among all transformers; U tmax is the maximum rated voltage among all transformers; P th is the rated capacity of the h-th transformer; n T is the number of transformers; p = 1, 2,..., n T , h = 1, 2,..., n T ;
[0073] According to the criticality values of each transformer, the transformer criticality weight matrix is obtained as
[0074] S5. According to the topological structure and voltage level of the transmission lines, conduct a criticality analysis on the tie lines in the backup power grid to obtain the tie line criticality weight matrix of each tie line; specifically, it includes the following steps:
[0075] Use the following formula to calculate the criticality value W of the q-th tie line lp :
[0076]
[0077] In the formula, n lq is the number of nodes connected by the q-th tie line; n T is the number of transformers; n G is the number of generators; U lq is the rated voltage of the q-th tie line; U lmin is the minimum rated voltage among all tie lines; U lmax is the maximum rated voltage among all tie lines;
[0078] According to the criticality values of each tie line, the tie line criticality weight matrix is obtained as
[0079] S6. According to the matrices obtained in steps S2 - S5, calculate the criticality matrix of the N - 1 faults of the backup power grid, and complete the screening of the N - 1 critical faults of the backup power grid according to the criticality matrix; specifically, it includes the following steps:
[0080] Construct the intermediate criticality matrix W as where W G is the generator criticality weight matrix; W T is the transformer criticality weight matrix; W L is the tie line criticality weight matrix;
[0081] The criticality matrix K for the guaranteed power grid's N-1 faults is calculated as K = CW, where C is the incidence matrix;
[0082] Expand the criticality matrix K to obtain where K i is the criticality index of the i-th fault, and the larger the value of K i , the more severe the i-th fault; at this time, in the subsequent operation process of the guaranteed power grid, more attention needs to be paid to the i-th fault, and more targeted measures should be taken.
[0083] The following further illustrates the method of the present invention in combination with a specific embodiment:
[0084] Taking the IEEE standard 3-machine 9-bus standard test system as an example, the effectiveness of the method of the present invention is verified.
[0085] The 3-machine 9-bus system is as Figure 3 shown. The 3-machine 9-bus system includes 3 synchronous generators, 3 transformers, 9 buses, and 6 tie lines. All generators are equipped with IEEE type 1 excitation and governors. In addition, the system also includes 3 constant impedance loads, with a total active power capacity and reactive power capacity of 315 MW and 115 MVAr respectively.
[0086] According to the method of the present invention, the incidence matrix C is calculated as
[0087]
[0088] The criticality weight matrix W of the generator G is
[0089] The criticality weight matrix W of the transformer T is
[0090] The criticality weight matrix W of the line L is
[0091]
[0092] The criticality weight matrix W is
[0093]
[0094] The N-1 fault criticality matrix is
[0095]
[0096] According to the elements in the N-1 fault criticality matrix, sort the N-1 fault criticality according to importance, as shown in Table 1:
[0097] Table 1 Schematic Diagram of N-1 Fault Importance Ranking
[0098] N-1 fault Importance N-1 fault Importance N-1 fault Importance Bus 2 0.5025 Bus 1 0.2585 Bus 8 - Bus 9 0.0508 G2 0.4829 G1 0.2405 Bus 6 0.0507 T2 0.3789 Bus 9 0.0911 Bus 5 0.0496 T3 0.3167 Bus 7 0.0848 Bus 4 - Bus 5 0.0481 T1 0.3163 Bus 4 0.0792 Bus 4 - Bus 6 0.0465 Bus 3 0.2836 Bus 6 - Bus 9 0.0636 Bus 7 - Bus 8 0.0458 G3 0.2616 Bus 5 - Bus 7 0.0592 Bus 8 0.0453
[0099] As can be seen from Table 1, the fault of bus 2 has the highest importance, indicating that this fault has the greatest importance. If this fault occurs, its influence range is the largest and the fault is more serious. At the same time, it can also be known from Table 1 that the higher the ranking of the fault, the greater the importance of the fault. If this fault occurs, its influence range is larger and the fault is more serious.
[0100] Such as Figure 4 shown is the schematic diagram of the functional modules of the system of the present invention: The system for implementing the method for screening N-1 key faults for a guaranteed power grid provided by the present invention specifically includes a data acquisition module, an incidence matrix calculation module, a generator criticality weight matrix calculation module, a transformer criticality weight matrix calculation module, a tie-line criticality weight matrix calculation module, and an N-1 key fault screening module; the output end of the data acquisition module is simultaneously connected to the input ends of the incidence matrix calculation module, the generator criticality weight matrix calculation module, the transformer criticality weight matrix calculation module, and the tie-line criticality weight matrix calculation module; the output ends of the incidence matrix calculation module, the generator criticality weight matrix calculation module, the transformer criticality weight matrix calculation module, and the tie-line criticality weight matrix calculation module are simultaneously connected to the N-1 key fault screening module; the data acquisition module is used to acquire the parameter data of the guaranteed power grid and upload the data to the incidence matrix calculation module, the generator criticality weight matrix calculation module, the transformer criticality weight matrix calculation module, and the tie-line criticality weight matrix calculation module; the incidence matrix calculation module is used to perform N-1 fault scanning on the guaranteed power grid to obtain an N-1 fault set, determine the incidence matrix of each fault in the fault set with the system based on the concentric relaxation principle, and upload the incidence matrix to the N-1 key fault screening module; the generator criticality weight matrix calculation module is used to perform criticality analysis on the generators in the guaranteed power grid according to the capacity and voltage level to obtain the generator criticality weight matrix of each generator and upload the result to the N-1 key fault screening module; the transformer criticality weight matrix calculation module is used to perform criticality analysis on the transformers in the guaranteed power grid according to the capacity, voltage level, and the state of accessing the power grid to obtain the transformer criticality weight matrix of each transformer and upload the result to the N-1 key fault screening module; the tie-line criticality weight matrix calculation module is used to perform criticality analysis on the tie-lines in the guaranteed power grid according to the topological structure and voltage level of the transmission lines to obtain the tie-line criticality weight matrix of each tie-line and upload the result to the N-1 key fault screening module; the N-1 key fault screening module is used to calculate the criticality matrix of the N-1 faults of the guaranteed power grid according to the received data information and complete the screening of the N-1 key faults of the guaranteed power grid according to the criticality matrix.
Claims
1. A method for screening N-1 critical faults for a guaranteed power grid, comprising the following steps: S1. Determine the guaranteed power grid corresponding to the target power grid and obtain the parameter data of the guaranteed power grid; S2. Conduct an N-1 fault scan on the guaranteed power grid to obtain an N-1 fault set, and determine the incidence matrix of each fault in the fault set and the system based on the concentric relaxation principle; specifically, it includes the following steps: The obtained N-1 fault set is S = {ρ|ρ∈S G or ρ∈S T or ρ∈S L}, where ρ is an element in the N-1 fault set; ρ∈S G indicates that the fault belongs to a generator fault, ρ∈S T indicates that the fault belongs to a transformer fault, ρ∈S L indicates that the fault belongs to a tie line fault; Calculate the electrical distance d between any two nodes i and j in the guaranteed power grid ij : d ij =z ii +z jj -z ij -z ji In the formula, z ii is the self-impedance of node i; z jj is the self-impedance of node j; z ij is the mutual impedance between node i and node j; z ji is the mutual impedance between node j and node i; Construct the incidence matrix C as: In the formula, n = n G +n T +n L where n G is the number of generators, n T is the number of transformers, n L is the number of tie lines; the element c ij represents the connection relationship between node i and node j, and the value is i = 1, 2,..., n, j = 1, 2,..., n; S3. According to the capacity and voltage level, conduct a criticality analysis on the generators in the guaranteed power grid to obtain the generator criticality weight matrix of each generator; S4. According to the capacity, voltage level and the state of accessing the power grid, conduct a criticality analysis on the transformers in the guaranteed power grid to obtain the transformer criticality weight matrix of each transformer; S5. According to the topological structure and voltage level of the transmission line, conduct a criticality analysis on the tie lines in the backup power grid to obtain the tie line criticality weight matrix of each tie line; S6. Based on the matrices obtained in steps S2 - S5, calculate the criticality matrix of the N - 1 faults of the backup power grid, and complete the screening of the N - 1 critical faults of the backup power grid according to the criticality matrix; specifically, it includes the following steps: Construct the intermediate criticality matrix W as where W G is the generator criticality weight matrix; W T is the transformer criticality weight matrix; W L is the tie line criticality weight matrix; Calculate the criticality matrix K of the N - 1 faults of the backup power grid as K = CW, where C is the incidence matrix; Expand the criticality matrix K to obtain where K i is the criticality index of the i - th fault, and the larger the value of K i , the more serious the i - th fault is.
2. The method for screening N - 1 critical faults of the backup power grid according to claim 1, characterized in that The obtaining of the parameter data of the backup power grid described in step S1 specifically includes the following steps: Determine the operation mode of the backup power grid, and determine important stations, key lines, and guaranteed power sources according to the power grid plan; The set of generators in the guaranteed power grid is The set of transformers is The set of tie lines is Among them, G i is the i-th generator, and n G is the number of generators, T i is the i-th transformer, and n T is the number of transformers, L i is the i-th tie line, and n L is the number of tie lines.
3. The method for screening N - 1 critical faults of the backup power grid according to claim 2, characterized in that The criticality analysis of the generators in the backup power grid according to the capacity and voltage level described in step S3 to obtain the generator criticality weight matrix of each generator specifically includes the following steps: The critical value W of the m-th generator is calculated using the following formula gm :[[]]END]] Where S gm is the rated capacity of the m-th generator; U gm is the rated voltage of the m-th generator; U gmin is the minimum rated voltage among all generators; S gt is the rated capacity of the t-th generator; n G is the number of generators; U gmax is the maximum rated voltage among all generators; m = 1, 2, ..., n G , t = 1, 2, ..., n G ; According to the criticality values of each generator, the generator criticality weight matrix is obtained as 4. The method for screening N - 1 critical faults of the backup power grid according to claim 3, characterized in that The criticality analysis of the transformers in the backup power grid according to the capacity, voltage level, and the state of connecting to the power grid described in step S4 to obtain the transformer criticality weight matrix of each transformer specifically includes the following steps: The critical value W of the p-th transformer is calculated using the following formula tp :[[-END]] where F tp is the state variable of the p-th transformer connected to the power grid, and if the p-th transformer is connected to the power grid, then F tp = 1, and if the p-th transformer is not connected to the power grid, then F tp = 0; P tp is the rated capacity of the p-th transformer; U tp is the rated voltage of the p-th transformer; U tmin is the minimum rated voltage among all transformers; U tmax is the maximum rated voltage among all transformers; P th is the rated capacity of the h-th transformer; n T is the number of transformers; p = 1, 2,..., n T , h = 1, 2,..., n T ; According to the criticality values of each transformer, the transformer criticality weight matrix is obtained as 5. The method for screening N - 1 critical faults of the backup power grid according to claim 4, characterized in that The criticality analysis of the tie lines in the backup power grid according to the topological structure and voltage level of the transmission lines described in step S5 to obtain the tie line criticality weight matrix of each tie line specifically includes the following steps: The critical value W of the q-th tie line is calculated using the following formula lp :[[]]END]] where n lq is the number of nodes connected by the q-th tie line; n T is the number of transformers; n G is the number of generators; U lq is the rated voltage of the q-th tie line; U lmin is the minimum rated voltage among all tie lines; U lmax is the maximum rated voltage among all tie lines; According to the criticality values of each tie line, the tie line criticality weight matrix is obtained as 6. A system for implementing the N-1 key fault screening method for the guaranteed power grid described in any one of claims 1 to 5, characterized in that Specifically, it includes a data acquisition module, an incidence matrix calculation module, a generator criticality weight matrix calculation module, a transformer criticality weight matrix calculation module, a tie line criticality weight matrix calculation module, and an N-1 key fault screening module; the output end of the data acquisition module is simultaneously connected to the input ends of the incidence matrix calculation module, the generator criticality weight matrix calculation module, the transformer criticality weight matrix calculation module, and the tie line criticality weight matrix calculation module; the output ends of the incidence matrix calculation module, the generator criticality weight matrix calculation module, the transformer criticality weight matrix calculation module, and the tie line criticality weight matrix calculation module are simultaneously connected to the N-1 key fault screening module; the data acquisition module is used to acquire the parameter data of the backup power grid and upload the data to the incidence matrix calculation module, the generator criticality weight matrix calculation module, the transformer criticality weight matrix calculation module, and the tie line criticality weight matrix calculation module; The associated matrix calculation module is used to perform N-1 fault scanning on the guaranteed power grid to obtain the N-1 fault set, determine the associated matrix between each fault in the fault set and the system based on the concentric relaxation principle, and upload the associated matrix to the N-1 critical fault screening module; the generator criticality weight matrix calculation module is used to perform criticality analysis on the generators in the guaranteed power grid according to the capacity and voltage level, obtain the generator criticality weight matrix of each generator, and upload the result to the N-1 critical fault screening module; the transformer criticality weight matrix calculation module is used to perform criticality analysis on the transformers in the guaranteed power grid according to the capacity, voltage level and the state of accessing the power grid, obtain the transformer criticality weight matrix of each transformer, and upload the result to the N-1 critical fault screening module; the tie-line criticality weight matrix calculation module is used to perform criticality analysis on the tie-lines in the guaranteed power grid according to the topological structure and voltage level of the transmission lines, obtain the tie-line criticality weight matrix of each tie-line, and upload the result to the N-1 critical fault screening module; the N-1 critical fault screening module is used to calculate the criticality matrix of the N-1 faults of the guaranteed power grid according to the received data information, and complete the N-1 critical fault screening of the guaranteed power grid according to the criticality matrix.
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Patent Citations
Power distribution network expanding device and method based on anti-disaster denaturation indexes
CN103714398A