CN112487658B - Method, device and system for identifying key nodes of power grid - Google Patents

Abstract

The invention belongs to the field of electric power data processing, and relates to a method, a device and a system for identifying key nodes of a power grid; the method comprises the steps of constructing a power-efficient power grid topological structure according to validity rules of power node injection power and line transmission power in a power grid; calculating the average electrical distance and the electrical betweenness center of the power nodes in the power grid topological structure, respectively distributing weight vectors, and constructing a criticality evaluation model of the nodes; and calculating a power node core value according to the criticality evaluation model, performing recursive network decomposition according to the interval to which the power node core value belongs, and taking the power node contained in the last layer of sub-network as an identified key node set. According to the method, the rule characteristics of the large-scale power system are excavated according to a series of rules, the standard power grid topological structure is constructed, the network characteristics and the electrical characteristics of the power system are comprehensively considered, a multi-factor-based power grid key node identification model is established, and the efficiency and the accuracy of key node identification in the complex power grid system are improved.

Description

A method, device and system for identifying key nodes of power grid

technical field

The invention belongs to the field of power data processing, and relates to a method, device and system for identifying key nodes of a power grid.

Background technique

In recent years, the rapid development of various emerging technologies has brought a qualitative leap in people's living standards. The power system is an important infrastructure for the development of all science and technology, and has made outstanding contributions to the development of other social networks such as the Internet, communication networks, and transportation networks. As the scale of the grid continues to expand and the integration of components increases, the structural characteristics of the grid become more and more complex, and this increase in complexity plays a significant role in maintaining the efficient transmission of power. Although the modern power grid has formed a large cross-regional power grid pattern with high voltage level and long-distance transmission, and basically realized the interconnection and interoperability of the network architecture, the safe and stable operation of the power grid is still a major headache and difficult to solve. The safe and stable operation of the power system depends on many factors, such as the hardware equipment of the power grid itself, the climate of the surrounding environment of the power grid, etc. Among them, the safety of some key parts of the power grid is a factor that cannot be ignored. Therefore, it is an important means to maintain the robustness of the power system to accurately identify the key nodes or lines in the power grid system and take certain protective measures.

Most of the previous researches on large-scale power outages are based on reductionism. The essence is to first discover the laws by simplifying the research objects, and then restore the system laws. Usually, theoretical research is limited to the physical properties of the components themselves. The reductionism method usually describes the power grid as a set of multi-dimensional differential-algebraic equations, and then solves them through computer simulation, ignoring the internal evolution characteristics of the entire system to a certain extent, so a new idea is needed to study the power grid characteristics. The complex network theory abstracts the busbars as network nodes and the transmission wires as network links, so that the power grid is regarded as a network with interactions between units or individuals, which provides a new way to study the structure of the power grid and the cascading reaction process. ideas.

Based on the existing technical research, it can be found that many large-scale power grid failure accidents are caused by the failure of some special nodes or lines in the system. Therefore, accurately identifying the key nodes or lines in the power grid system and taking targeted protection measures is an effective means to prevent large-scale cascading failures in the power grid. At present, most of the key node identification of power grid system is mainly from the perspective of power grid topology, combined with general network models in complex network theory (such as small-world network model, scale-free network model and regular network model, etc.) and common network models. Indicators (such as node clustering coefficient, degree, etc.) are used to identify key nodes in the power system. However, in a complex power system, the criticality of nodes in the power grid cannot be analyzed only from the perspective of topology, but more needs to be considered from the actual physical properties of the power system, such as the directional transmission of power in the power grid, certain The influence of the change of the state of each node on the power flow of the entire power grid, etc.

In addition, traditional sorting algorithms (such as k_shell algorithm, TOPSIS algorithm, Pagerank algorithm, etc.) have certain limitations in many practical application scenarios. On the one hand, the existing technology only considers the basic characteristics of the network topology, and is not related to the actual power grid scenario. Combined, for example, there is a lack of consideration for power transmission, so certain improvements need to be made to the existing technology in order to more accurately identify key nodes in the grid system.

SUMMARY OF THE INVENTION

In view of this, the purpose of the present invention is to provide a method for identifying key nodes in a power grid based on an improved k_shell algorithm, which combines the network topology and electrical characteristics of the power system to establish a new model for evaluating node criticality with multiple factors. To improve, a method, device and system for identifying key nodes of power grid are proposed.

The scheme adopted by the present invention to solve the above-mentioned technical problems includes:

In a first aspect of the present invention, the present invention provides a method for identifying key nodes of a power grid, the identifying method comprising the following steps:

Step 1) According to the validity rules of the power injection power of the power node and the transmission power of the line in the power grid, the power grid topology structure of the power validity is constructed;

Step 2) in the power grid topology structure, calculate the average electrical distance and electrical betweenness center of the power node, and distribute the weight vector respectively, and construct the criticality evaluation model of the node;

Step 3) Calculate the power node core value according to the criticality evaluation model, perform recursive network decomposition according to the interval to which the power node core value belongs, and use the power nodes included in the last layer of sub-networks as the identified key node set.

In a second aspect of the present invention, the present invention also provides an identification device for a key node of a power grid, the identification device comprising:

The topology structure building module is used to construct a power efficient grid topology structure according to the validity rules of power injection power and line transmission power in the power grid;

The criticality evaluation module is used to calculate the average electrical distance and electrical betweenness center of power nodes, and assign weight vectors respectively to construct a criticality evaluation model;

a core value calculation module, configured to calculate the core value of each power node according to the criticality evaluation model;

The interval division module is used to divide a plurality of intervals according to the core value of the power node, and determine the minimum interval among them;

a topology update module, used for deleting the power nodes in the minimum interval, and returning to the core value calculation module after updating the grid topology structure;

The node output module is used to output the power node of the last interval, which is the set of key points.

In a third aspect of the present invention, the present invention also provides an identification system for key nodes of a power grid, the identification system comprising:

The data acquisition module is used to collect the power data of the power nodes in the power grid;

The identification device of the key node of the power grid is used to identify the collected power data of the power node, and output a set of key points.

Beneficial effects of the present invention:

1. The present invention constructs a grid topology structure with power validity according to the validity rules of power node injection power and line transmission power in the power grid. The grid topology structure constructed by the present invention can reflect the electrical properties of complex power systems. Compared with the existing power grid topology, the computing efficiency of the power grid structure is improved to a certain extent, so that the key nodes in the power grid can be quickly and accurately extracted.

2. The present invention proposes a new node criticality evaluation model according to the average path length and betweenness center of the power node, combined with electrical characteristics, and uses the AHP to train to obtain the weight vector of the criticality evaluation model; the evaluation The model also considers the network characteristics and electrical characteristics of the power system, which can more objectively reflect the criticality of power nodes;

3. The present invention redefines the core values of nodes according to the criticality evaluation model, divides the core values of all nodes into intervals, performs recursive network decomposition according to the space to which the core values of the nodes belong, and takes the nodes contained in the last layer of sub-networks as the final layer. set of key points. This method improves the limitation of k_shell algorithm in power grid application scenarios, and can improve the accuracy of identifying key nodes in the power grid.

Description of drawings

In order to make the objectives, technical solutions and advantages of the present invention clearer, the present invention will be preferably described in detail below with reference to the accompanying drawings, wherein:

Fig. 1 is the overall structure diagram of the key node identification model of the power grid constructed by the present invention;

2 is a flowchart of a method for identifying key nodes of a power grid according to an embodiment of the present invention;

Fig. 3 is the flow chart of the distribution weight of the analytic hierarchy process adopted in the embodiment of the present invention;

Fig. 4 is the key node set screening flow chart of the embodiment of the present invention adopting the improved k_shell algorithm;

FIG. 5 is a structural diagram of an apparatus for identifying key nodes of a power grid according to an embodiment of the present invention.

Detailed ways

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, but not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

The present invention studies the characteristics of large-scale power systems based on complex network theory. By comprehensively considering the network characteristics and electrical characteristics of the power system, combined with a sorting algorithm based on multi-factor improvement, it can more accurately identify the power system in the power system. key node.

Fig. 1 is an architecture diagram of the node identification model adopted by the present invention. As shown in Fig. 1, after abstracting and normalizing the power data collected by the power system in the present invention, the power injection power of the power node and the validity rules of the line transmission power are used in accordance with the present invention. , a power grid topology structure is formed, wherein the nodes in the power grid topology structure include power generation nodes, intermediate nodes (transmission nodes) and load nodes. In the power grid topology structure, the average electrical aggregation of the power nodes and the electrical betweenness center are calculated, According to the analytic hierarchy process, the weights are assigned to them, so as to construct a new criticality evaluation model; the network is decomposed according to the improved k-shell algorithm of the interval division method to extract the key node set.

FIG. 2 is a flowchart of a method for identifying key nodes of a power grid according to the present invention. As shown in FIG. 2 , the identifying method includes the following steps:

Step 1) According to the validity rules of the power injection power of the power node and the transmission power of the line in the power grid, the power grid topology structure of the power validity is constructed;

In this embodiment, the power station, substation or intermediate connection device in the power system is abstracted as the power node of the power network, and the transmission line is used as the power edge of the network; based on the validity of the power injected by the power node in the power grid and the power transmitted by the line According to the rules, the power nodes in the grid are classified, and it is stipulated that every two power nodes are connected by at most one edge, so as to construct a power efficient grid topology.

Among them, the validity rule of node injection power refers to that, for the entire power grid system, the node is subdivided into power generation nodes, transmission nodes and load nodes according to the net injected power value of the node; specifically, for the entire power grid system, if the node is If the net injection power of the node is positive, the node is a power generation node that injects active power into the grid; if the net injection power of the node is negative, the node is a load node that receives power from the grid; If the power is zero, the node is a transmitting node.

The power efficiency rule of circuit transmission means that the strategy of forward superposition and reverse cancellation is adopted, and it is stipulated that only one edge with non-negative transmission power is connected between node pairs; The lines are connected. Since there may be differences in the magnitude and direction of the power transmitted by each line, the strategy of forward superposition and reverse cancellation is adopted to process the transmission power of multiple lines. An edge with a non-negative transmit power is connected.

Step 2) in the power grid topology structure, calculate the average electrical distance and electrical betweenness center of the power node, and distribute the weight vector respectively, and construct the criticality evaluation model of the node;

First of all, for the average electrical distance of power nodes, on the basis of obtaining the grid topology structure above, considering the average path length of power nodes and combining the electrical characteristics of the power grid, the calculation method is as follows:

Based on the shortest path algorithm, the shortest path i,k ₁ , _{k 2} ,...,km ,j between any power node pair ij is solved, and the length of the shortest path is solved based on the load of the power node itself and the transmission power of the line. The sum of the transmission powers P _ij , expressed as:

Among them, w _ij refers to the actual load between power node i and power node j, which is defined as w _ij =min(S _i ,S _j ), and w _ii =0, S _i refers to the rated power generation of power node i capacity, S _j is the rated power generation capacity of power node j.

Among them, the shortest path algorithm can use the floyd-warshall algorithm, and the Floyd algorithm is a kind of algorithm that uses the idea of dynamic programming to find the shortest path algorithm between multiple source points in a given weighted graph, which can more accurately Find the shortest path between any pair of power nodes ij.

The electrical distance d _ij between any pair of nodes refers to the ratio of the power sum to the length of the shortest path between two nodes, which is defined as follows:

Among them, M _ij refers to the length of the shortest or most efficient path between power node i and power node j. If power node i and power node j are unreachable, then M _ij =+∞, and M _ii = 1.

On the basis of the shortest path between power nodes, the present invention provides the definition of the average electrical distance of power nodes, which is expressed as:

Among them, D _i represents the average electrical distance of power node i; V represents the set of power nodes in the power grid; N refers to the total number of power nodes in the power grid.

Secondly, after solving the average electrical distance of the power nodes, still based on the topology of the power grid, for the electrical betweenness center of the electrical node, combined with the electrical characteristics of the power grid, the present invention defines the electrical betweenness center of three power nodes respectively;

The betweenness center of a node in a general complex network is usually used to characterize the criticality of the node in the entire network, depending on the number of times the shortest path or the most efficient path in the network system passes through the node. The betweenness center of is defined as follows:

After the present invention normalizes it, it is expressed as:

where σ _ij is the number of shortest or most efficient paths between power node i and power node j, and σ _ij (k) is the number of shortest or most efficient paths between power node i and power node j through power node k Quantity, G and L respectively refer to the set of power generation nodes and the set of load nodes.

On the basis of the above normalization of the betweenness center index, the present invention also combines the electrical and directional transmission characteristics of the power grid to define the electrical betweenness center index for three situations, such as power generation nodes, load nodes, and intermediate nodes, respectively. , expressed as follows:

则表示电力节点k属于中间节点集合；考虑到电网中电力节点的有向性，P_ki表示发电节点k和其他电力节点i之间的通过最短或最有效路径传输的功率总和；P_ik表示其他电力节点i和负荷节点k之间的通过最短或最有效路径传输的功率总和。Among them, P _ij refers to the sum of power transmitted between power node i and power node j through the shortest or most efficient path, G and L refer to the set of power generation nodes and the set of load nodes respectively; where in the above formula

Then it means that the power node k belongs to the set of intermediate nodes; considering the directionality of the power nodes in the power grid, P _ki represents the sum of the power transmitted between the power generation node k and other power nodes i through the shortest or most efficient path; P _ik represents the other The sum of the power transmitted over the shortest or most efficient path between power node i and load node k.

并根据节点关键度设置的客观原则，构建新的节点关键度评估模型。After the average electrical distance and the electrical betweenness center of the power nodes are solved, the present invention also assigns weight vectors to the average electrical distance and the electrical betweenness center based on the AHP.

And according to the objective principle of node criticality setting, a new node criticality evaluation model is constructed.

Fig. 3 provides the flow chart of the weight distribution method of the AHP adopted in the embodiment of the present invention, as shown in Fig. 3, the distribution process includes the following content:

Establish a hierarchical structure model, that is, input the decision criteria of the average electrical distance of the power nodes and the center of electrical betweenness;

A judgment matrix is constructed, and relative scales are used to compare the decision criteria in pairs, so as to obtain a judgment matrix A:

where a _ij refers to the scale value of the pairwise comparison between the decision criteria. In order to verify the rationality of the scale value setting, the consistency ratio is defined to check whether the constructed judgment matrix is consistent, so as to determine the weight vector of the index; then, the consistency test of matrix A is required.

则A是一致性矩阵，且秩为1，唯一非零特征值为λ，将该特征值所对应的特征向量进行归一化处理之后作为权重向量ψ；若A不是一致性矩阵，则需要检验A的不一致性是否在合理范围内。取A的最大特征值λ，定义一致性指标CI：If A satisfies

Then A is a consistency matrix with a rank of 1, the only non-zero eigenvalue is λ, and the eigenvector corresponding to the eigenvalue is normalized as a weight vector ψ; if A is not a consistency matrix, it needs to be checked Whether the inconsistency of A is within reason. Take the largest eigenvalue λ of A to define the consistency index CI:

In order to measure the size of CI more objectively, m consistency matrices are randomly constructed, and the random consistency index RI is introduced:

Then the consistency ratio can be defined:

Only when CR<0.1 is satisfied, it is considered that A has satisfactory consistency, and the eigenvector corresponding to the largest eigenvalue λ of A is normalized to obtain the weight vector ψ. If CR<0.1 is not satisfied, the scale value of the judgment matrix A needs to be reset until a qualified judgment matrix is obtained.

Step 3) Calculate the power node core value according to the criticality evaluation model, perform recursive network decomposition according to the interval to which the power node core value belongs, and use the power nodes included in the last layer of sub-networks as the identified key node set.

Fig. 4 is the key node set screening flow chart adopted in the embodiment of the present invention; as shown in Fig. 4, the present invention performs network decomposition based on the improved k_shell algorithm, and finally identifies the key node set of the power system, and mainly needs to perform the following steps:

根据节点的平均电气距离越小且电气介数中心越大，说明节点对于电网系统越关键的原则，构建新的节点关键度评估模型：1) On the basis of using the Analytic Hierarchy Process, the weight vector of the average electrical distance of power nodes and the center of electrical betweenness is obtained

According to the principle that the smaller the average electrical distance of the node and the larger the electrical betweenness center, the more critical the node is to the power grid system, a new node criticality evaluation model is constructed:

表示第一权重向量，D_i表示电力节点i的平均电气距离，

表示第二权重向量；B_e(i)表示电力节点i的电气介数中心。Among them, K(i) represents the criticality of power node i;

represents the first weight vector, D _i represents the average electrical distance of power node i,

represents the second weight vector; Be ( _i ) represents the electrical betweenness center of power node i.

According to the criticality evaluation model, a new calculation formula of node core value is defined as:

Among them, KS(i) represents the core value of power node i; _Kmin represents the minimum value of the criticality of all nodes in the power grid; _Kmax represents the maximum value of the criticality of all power nodes in the power grid; K(i) represents the power node the criticality of i.

In this embodiment, the maximum and minimum normalization method is adopted, and the key value is proportionally scaled as the new node core value. After the core value is fixed in the [0,1] interval, the centralized distribution degree of the core value can be enhanced, which is convenient for subsequent Divide the space for recursive network decomposition.

的电力节点，节点去除后，所述电网拓扑结构中剩下一个子图，重新计算子图中各电力节点核值，如果该子图中依然有电力节点的核值属于

区间内，则继续删除这些电力节点，直到最后剩下一个子图G₁中所有电力节点的核值均不在

区间内，那些被删除的电力节点则属于S(1)集合中；2) Calculate the core value of each power node, and divide all the core values into _{11 intervals (Π 1 ,} Π ₂ ..., Π _l1 ) according to reasonable differences, and remove those core values that belong to the minimum interval

After the node is removed, there is a subgraph left in the grid topology structure, and the core value of each power node in the subgraph is recalculated. If the core value of the power node in the subgraph still belongs to

In the interval, continue to delete these power nodes until the last remaining subgraph G ₁ has no core value of all power nodes in the

In the interval, those deleted power nodes belong to the S(1) set;

In some embodiments, the key value calculated by the criticality evaluation model is directly used as the interval division index of the core value of the power node; wherein the division standard of the core value space includes calculating the key value of all nodes, according to the distribution of the key value. If the distribution is relatively dense, the space range is divided into small spaces, otherwise, large spaces can be divided.

In other embodiments, in addition to the above-mentioned division according to key values, referring to the above-mentioned embodiments, this embodiment can also divide the kernel value space according to the new kernel value calculation formula provided by the present invention.

区间内的电力节点，其中

满

最后得到子图G₂，G₂中所有电力节点的核值均大于区间

内的值；3) Similar to the above steps, deleting the kernel value belongs to

power nodes within the interval, where

Full

Finally, the subgraph G ₂ is obtained, and the kernel values of all power nodes in G ₂ are larger than the interval

the value within;

4) By analogy, until all the core values of power nodes are located in an interval, it is the set of key power nodes in the grid topology.

It can be understood that the recursive network of the present invention and the last layer of sub-networks all refer to the grid topology including the grid topology before the update and the updated subgraph. In addition, the improvement of the present invention to the k-shell algorithm mainly lies in the division of Out of space for recursive network decomposition and improved traditional kernel value calculation.

Fig. 5 shows a structure diagram of an identification device for a key node of a power grid according to the present invention. As shown in Fig. 5, the identification device includes:

The topology structure building module is used to construct a power efficient grid topology structure according to the validity rules of power injection power and line transmission power in the power grid;

The criticality evaluation module is used to calculate the average electrical distance and electrical betweenness center of power nodes, and assign weight vectors respectively to construct a criticality evaluation model;

a core value calculation module, configured to calculate the core value of each power node according to the criticality evaluation model;

The interval division module is used to divide a plurality of intervals according to the core value of the power node, and determine the minimum interval among them;

a topology update module, used for deleting the power nodes in the minimum interval, and returning to the core value calculation module after updating the grid topology structure;

The node output module is used to output the power node of the last interval, which is the set of key points.

In this embodiment, the core value calculation module and the topology update module not only use the interval division module as an intermediate transition, but also adopt a direct connection method. , divide these power nodes into different intervals, in the topology update module, according to the k-shell method, remove the power nodes in the minimum interval, and update the power grid topology, taking the updated power grid topology as a subgraph, Recalculate the core value of each power node in the subgraph through the core value calculation module. First, remove the power nodes that still exist in the minimum interval in the subgraph; then continue to follow the k-shell method to remove the sub-cell interval This process is repeated repeatedly until all the core values of the power nodes are located in the last interval, that is, the last subgraph, then all the power node sets in the subgraph are regarded as the key power in the grid topology. collection of nodes.

In some embodiments, the present invention also provides an identification system for key nodes of a power grid, the identification system includes:

The data acquisition module is used to collect the power data of the power nodes in the power grid;

The identification device of the key node of the power grid is used to identify the collected power data of the power node, and output a set of key points.

It can be understood that the method, device and system for identifying key nodes in the present invention belong to the same inventive concept, and their corresponding features can be referred to each other, and the present invention will not describe them one by one.

In the description of the present invention, it should be understood that the terms "coaxial", "bottom", "one end", "top", "middle", "the other end", "upper", "one side", "top" "," "inside", "outside", "front", "center", "both ends", etc. indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, only for the convenience of describing the present invention and The description is simplified rather than indicating or implying that the device or element referred to must have a particular orientation, be constructed and operate in a particular orientation, and therefore should not be construed as limiting the invention.

In the present invention, unless otherwise expressly specified and limited, terms such as "installation", "arrangement", "connection", "fixation" and "rotation" should be understood in a broad sense, for example, it may be a fixed connection or a It can be a detachable connection, or integrated; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between the two elements, Unless otherwise clearly defined, those of ordinary skill in the art can understand the specific meanings of the above terms in the present invention according to specific situations.

Although embodiments of the present invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, and substitutions can be made in these embodiments without departing from the principle and spirit of the invention and modifications, the scope of the present invention is defined by the appended claims and their equivalents.

Claims (7)

1. A method for identifying a key node of a power grid is characterized by comprising the following steps:

step 1) constructing a power-efficient power grid topological structure according to validity rules of power node injection power and line transmission power in a power grid;

step 2) calculating the average electrical distance and the electrical permittivity center of the power node in the power grid topological structure, respectively distributing weight vectors, and constructing a criticality evaluation model of the node;

the calculation mode of the electric dielectric number center comprises the following steps:

wherein, P _ki Represents the sum of the power transmitted over the shortest or most efficient path between power node k and power node i; p _ik Represents the sum of the power transmitted through the shortest or most efficient path between power node i and power node k, G represents the set of power generation nodes; l represents a load node set; c _B (k) Representing a traditional betweenness center of the normalized power node k;

step 3) calculating a power node core value according to the criticality evaluation model, carrying out recursive network decomposition according to the interval to which the power node core value belongs, and taking the power node contained in the last layer of sub-network as an identified key node set;

the calculation mode of the power node core value comprises the following steps:

wherein ks (i) represents a core value of power node i; k _min Representing the minimum value of the criticality of all nodes in the power grid; k _max Representing the maximum value of criticality of all power nodes in the power grid; k (i) represents the criticality of power node i.

2. The method for identifying key nodes of the power grid according to claim 1, wherein the step 1) comprises dividing the power nodes into power generation nodes, transmission nodes and load nodes according to the net injection power values of the power nodes, and adopting a forward superposition and reverse cancellation strategy to connect only one edge with non-negative transmission power between the power nodes, so as to construct the power grid topology.

3. The method for identifying the key node of the power grid according to claim 1, wherein the key degree evaluation model of the node is represented as:

wherein k (i) represents criticality of power node i;

representing a first weight vector, D _i Represents the average electrical distance of the power node i,

representing a second weight vector; b is _e (i) Represents the electrical betweenness center of the power node i.

4. The method for identifying the key nodes of the power grid according to claim 1 or 3, wherein the calculation mode of the weight vector comprises the steps of constructing a hierarchical structure model of decision criteria of the average electrical distance and the electrical betweenness center of the nodes by adopting an analytic hierarchy process; comparing the two decision criteria pairwise by adopting relative scale to obtain a judgment matrix; and detecting whether the judgment matrixes have consistency according to the consistency ratio, and taking indexes of the judgment matrixes with consistency as corresponding weight vectors.

5. The method for identifying key nodes of a power grid according to claim 1, wherein the core values of all the power nodes are divided into a plurality of intervals, a minimum interval is determined, the power nodes in the minimum interval are removed, the power grid topology is updated, the core values of the remaining power nodes in the updated power grid topology are calculated, the steps of removing the power nodes and updating the calculation are repeated until the core values of all the power nodes are in the same interval, and all the power nodes in the interval are used as the identified key node set.

6. An identification device for a key node of a power grid, which is applied to the identification method for the key node of the power grid according to any one of claims 1 to 5, wherein the identification device comprises:

the topological structure constructing module is used for constructing a power-efficient power grid topological structure according to validity rules of power node injection power and line transmission power in a power grid;

the criticality evaluation module is used for calculating the average electrical distance and the electrical betweenness center of the power nodes, respectively distributing weight vectors and constructing a criticality evaluation model;

the core value calculation module is used for calculating the core value of each power node according to the criticality evaluation model;

the interval dividing module is used for dividing a plurality of intervals according to the core values of the power nodes and determining the minimum interval;

the topology updating module is used for deleting the power nodes in the minimum interval, updating the power grid topology structure and returning to the core value calculating module;

and the node output module is used for outputting the power node of the last interval, namely the power node is the key point set.

7. An identification system for a critical node of a power grid, the identification system comprising:

the data acquisition module is used for acquiring the power data of the power nodes in the power grid;

a power grid key node identification apparatus as claimed in claim 6, configured to identify the collected power data of the power node and output a key point set.

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