Intelligent power grid-oriented space-ground integrated multicast routing method

Abstract

The invention relates to a sky-ground integrated multicast routing method for a smart power grid. The method comprises the following steps: a source node broadcasts a beacon message to wake up a selected multicast member node; constructing a multicast tree composed of all multicast member nodes; for any two connected multicast member nodes in the multicast tree, if the two connected multicast member nodes cannot directly communicate, constructing a shortest routing path between the multicast member nodes according to relay nodes between the multicast member nodes as a routing link between the two multicast members; if the two connected multicast member nodes can directly communicate with each other, directly constructing a routing link between the two multicast member nodes; and carrying out multicast routing through the routing link among the multicast members. The reliability and efficiency of the whole intelligent power grid communication system are improved, and finally safe and stable operation of a power system is guaranteed.

Description

Technical Field

[0001] The present invention belongs to the field of communication technology, and in particular relates to a space-ground integrated multicast routing method for smart grids. Background Art

[0002] As the development direction of modern power systems, smart grids integrate advanced information technology, communication technology and power technology, aiming to achieve efficient, reliable, safe and intelligent operation of power systems. With the continuous expansion of the scale of smart grids and the increasing diversification of business types, the requirements for communication networks are becoming more and more stringent.

[0003] In smart grid communications, multicast is a crucial communication method. For example, in scenarios such as real-time monitoring data distribution of power systems and transmission of power dispatch instructions, multicast can efficiently transmit information to multiple related nodes, avoiding the waste of network resources caused by repeated data transmission in unicast mode, and significantly improving information transmission efficiency.

[0004] However, the smart grid communication network has unique complexity. On the one hand, its geographical coverage is extremely wide, covering various terrains such as cities, villages, and mountains, which makes the traditional ground communication network have insufficient signal coverage in some areas; on the other hand, the communication business of the smart grid has extremely high requirements for real-time and reliability. Any communication failure may cause abnormal operation of the power system and even cause safety accidents.

[0005] The emergence of integrated space-ground communication network provides a new solution for smart grid communication. It combines the advantages of satellite communication and ground communication. Satellite communication can achieve seamless coverage of a large area, making up for the coverage shortcomings of ground communication in remote areas or areas with complex terrain; while ground communication has certain advantages in communication capacity and transmission rate. The combination of the two can provide more reliable and efficient communication services for smart grids.

[0006] However, it is not easy to implement multicast routing in a space-ground integrated environment. Due to the differences in the characteristics of satellite communications and ground communications, such as the large transmission delay of satellite communications and the signal being easily affected by factors such as weather, and the restrictions on the geographical environment and base station distribution on ground communications, how to build efficient multicast routing in such a complex network environment to ensure that information is accurately and timely transmitted to all multicast member nodes has become a key issue that needs to be solved urgently.

[0007] At present, most of the existing multicast routing methods are designed for a single network environment and are difficult to be directly applied to the space-ground integrated smart grid communication scenario. Some traditional ground network multicast routing algorithms cannot effectively deal with problems such as latency and signal instability when facing the special situation of satellite links; and satellite network multicast routing algorithms often do not fully consider the resource utilization and node characteristics of the ground network. Therefore, there is an urgent need for a multicast routing method specifically for the space-ground integrated environment of the smart grid to meet the growing communication needs of the smart grid and ensure the stable and safe operation of the power system. Summary of the invention

[0008] In order to solve the problems existing in the background technology, the present invention provides a space-ground integrated multicast routing method for smart grid, comprising:

[0009] S1: The source node broadcasts a beacon message to wake up the selected multicast member nodes;

[0010] S2: Build a multicast tree consisting of all multicast member nodes;

[0011] S3: For any two connected multicast member nodes in the multicast tree, if the two connected multicast member nodes cannot communicate directly, the shortest routing path between the multicast member nodes is constructed according to the relay nodes between the multicast member nodes as the routing link between the two multicast members; if the two connected multicast member nodes can communicate directly, the routing link between the two multicast member nodes is directly constructed; multicast routing is performed through the routing link between the multicast members.

[0012] The present invention has at least the following beneficial effects

[0013] The present invention can flexibly deal with such complex situations by finding relay nodes to build the shortest routing path, ensuring that effective communication links can be established between multicast members under various circumstances, greatly enhancing the adaptability and robustness of the solution in different scenarios. It can provide a stable and efficient transmission path for various multicast communication services of the smart grid in an integrated space-ground network environment. It ensures that key information such as real-time monitoring data and dispatch instructions of the power system are accurately and timely transmitted to multiple related nodes, thereby improving the reliability and efficiency of the entire smart grid communication system, and ultimately ensuring the safe and stable operation of the power system. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 It is a schematic diagram of the method flow of the present invention;

[0015] Figure 2 It is a schematic diagram of the framework of the space-ground integrated network for smart grid of the present invention;

[0016] Figure 3A schematic diagram of constructing a multicast tree and routing links between multicast member nodes according to the present invention. DETAILED DESCRIPTION

[0017] The following describes the embodiments of the present invention by specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the illustrations provided in the following embodiments only illustrate the basic concept of the present invention in a schematic manner, and the following embodiments and features in the embodiments can be combined with each other without conflict.

[0018] See also Figure 1 , Figure 2 and Figure 3 The present invention provides a space-ground integrated multicast routing method for smart grid, comprising:

[0019] S1: The source node broadcasts a beacon message to wake up the selected multicast member nodes;

[0020] Preferably, the integrated space-ground network includes: m ground network nodes and n satellite network nodes, and all nodes are registered to the smart grid central server.

[0021] In this embodiment, the integrated space-ground smart grid includes: ground facilities (such as power plants, intelligent control and dispatching centers, transmission lines, substations, power terminal users and other ground network nodes and satellite nodes such as satellite equipment. When the ground network nodes transmit data, they can directly forward it through the ground communication link, and for remote areas, they can also be relayed through satellite nodes.

[0022] Assume that the ground-ground integrated network consists of k nodes, including the ground network node set G = {g 1 ,g 2 ,...,g m} and satellite node set S = {s 1 ,s 2 ,...,s n}, each node is assigned a unique identifier To distinguish it from other nodes, m represents the number of ground network nodes; n represents the number of satellite nodes; α is a Boolean variable, 0 represents satellite nodes and 1 represents ground nodes; when the source node needs to transmit data, it will randomly select M < K receiving nodes, M is the number of nodes participating in multicast transmission, which is called the multicast group size.

[0023] In step S1 of this embodiment, in order to achieve efficient multicast routing in the smart grid space-ground integrated environment, each multicast member node is assigned a unique label to clearly indicate its specific role in the multicast tree. Among them, "S" is specifically used to represent the source node, which is the source of information initiation and controls the start of the entire multicast process. "R" represents a large number of multicast member nodes, which are the receivers of information and are responsible for receiving and processing relevant data sent by the source node.

[0024] At this critical stage, the source node sends a special message containing the identifiers of all multicast member nodes. This message is like a key to open the door to communication, and its role is crucial. Due to the complex structure of the smart grid's integrated network and the large number of nodes, the sending of this message ensures that all nodes in the network know clearly whether they belong to the category of multicast member nodes. This is like a detailed list in a large and complex organization to let every member know whether they are in a specific task group. Once the nodes in the network receive the message, those nodes that are multicast members will respond quickly. They will immediately mark themselves with "R", which is like making a clear mark on their location on the map, indicating that they are ready. At the same time, they will actively prepare and devote themselves to the subsequent multicast routing process. When the source node sends this message, it will also clearly identify its own location information in the message. This location information is of great significance to the entire multicast process. It is like a navigation coordinate, providing a key basis for establishing accurate and efficient communication links between subsequent multicast member nodes and source nodes, enabling multicast member nodes to interact with source nodes more accurately and ensure smooth and efficient information transmission.

[0025] S2: Build a multicast tree consisting of all multicast member nodes;

[0026] Preferably, the constructing of a multicast tree consisting of all multicast member nodes comprises:

[0027] S21: connecting the satellite multicast member node to the terrestrial multicast member nodes within the coverage area;

[0028] S22: Initialize the search range of each multicast member node, and calculate the Euclidean distance between each multicast member node and the source node;

[0029] S23: for each multicast member node except the source node, searching for other multicast member nodes within the search range, if other multicast member nodes are found, executing step S24, otherwise executing step S26;

[0030] S24: Determine whether the Euclidean distance between the remaining searched multicast member nodes and the source node is less than the Euclidean distance between the current multicast member node and the source node; if so, add the remaining multicast member nodes as candidate multicast member nodes to the candidate multicast member node set; then determine whether the candidate multicast member node set is empty, if so, execute step S26, otherwise execute step S25;

[0031] S25: taking the candidate multicast member node with the smallest Euclidean distance to the source node in the candidate multicast node set as the optimal candidate multicast member node, and connecting the multicast member node to the optimal candidate multicast member node;

[0032] S26: If the current multicast member node does not find a qualified candidate multicast member node within the search range, the search range of the current multicast member node is expanded according to a preset ratio, and steps S23 to S26 are repeatedly performed within the search range until a multicast tree consisting of all multicast member nodes is constructed.

[0033] In order to explain step S2 in the present application in more detail, the present invention provides the following embodiments:

[0034] Assume that there are the following nodes in the smart grid space-ground integrated network: source node S, located at coordinates (50, 50) (here two-dimensional coordinates are used as an example, in actual applications it may be three-dimensional coordinates), satellite multicast member node S1, with a coverage area with itself as the center and a radius of r1 = 100. Ground multicast member nodes G1 (coordinates 30, 40), G2 (coordinates 70, 80), G3 ((coordinates 150, 180)), G4 ((coordinates 220, 230)), etc., are distributed in different geographical locations. Satellite multicast member node S1 starts up, and it detects ground multicast member nodes within its coverage area. After calculation, G3 and G4 are within the coverage area of ​​S1, so S1 establishes connections with G3 and G4 respectively. This step uses the wide coverage characteristics of satellites to initially integrate some ground nodes into the multicast network, just like building a preliminary architecture for space-ground communication. Initialize the search range of each multicast member node (including the source node S), assuming that the initial search range is a circular area with each node as the center and a radius of 30 kilometers. Calculate the Euclidean distance between each multicast member node and the source node S. For example, for G1, its Euclidean distance to the source node S is:

[0035]

[0036] Through this calculation, each node clarifies the spatial distance relationship between itself and the source node, providing a quantitative basis for the subsequent connection strategy. Taking G2 as an example, it searches for other multicast member nodes within its initial search range. Assuming that G1 is found within the range, step S24 is executed; if not, step S26 is executed.

[0037] Step S24: G2 determines whether the Euclidean distance between G1 and the source node S is less than the Euclidean distance between G2 and the source node S. G1-S ≈22.36, Because d G1-S <d G2-S , so G1 is added as a candidate multicast member node to the candidate multicast member node set. Then it is determined whether the candidate multicast member node set is empty. If it is not empty, step S25 is executed. This step screens out better connection candidate nodes by comparing distances, which helps to optimize the multicast tree structure.

[0038] Step S25: At this time, there is only G1 in the candidate multicast node set, and G1 is the candidate multicast member node with the smallest Euclidean distance to the source node, and G2 is connected to G1. In this way, each multicast member node is gradually connected, just like building branches, gradually forming the prototype of a multicast tree.

[0039] Step S26: If G2 does not find a candidate multicast member node that meets the conditions within the initial search range, the search range is expanded according to a preset ratio (e.g., 1.5 times), that is, the search range becomes a circular area with G2 as the center and a radius of 30×1.5=45. Then, steps S23-S26 are repeated within the new search range until all multicast member nodes (including the source node) are connected and a complete multicast tree is constructed.

[0040] In this embodiment, step S21 utilizes the coverage of satellite multicast member nodes to connect ground multicast member nodes, giving full play to the advantages of the integrated network of heaven and earth, expanding the coverage of the multicast network, enabling more nodes to participate in multicast communication, and meeting the widely distributed node communication needs of the smart grid. By calculating the Euclidean distance between each node and the source node, and selecting the connection node based on the distance (steps S22-S25), the constructed multicast tree structure is more compact and reasonable. Shorter paths can reduce data transmission delays and signal losses, improve communication efficiency and reliability, and meet the strict requirements of smart grids for real-time and accuracy of data transmission. The adaptive search range expansion mechanism of step S26 ensures that even in the case of uneven node distribution or complex network environment, all multicast member nodes (including source nodes) can be included in the multicast tree, enhancing the adaptability and robustness of the algorithm, and ensuring the integrity and stability of the integrated multicast communication of the smart grid.

[0041] S3: For any two connected multicast member nodes in the multicast tree, if the two connected multicast member nodes cannot communicate directly, the shortest routing path between the multicast member nodes is constructed according to the relay nodes between the multicast member nodes as the routing link between the two multicast members; if the two connected multicast member nodes can communicate directly, the routing link between the two multicast member nodes is directly constructed; multicast routing is performed through the routing link between the multicast members.

[0042] Preferably, the constructing the shortest routing path between the multicast member nodes according to the relay nodes between the multicast member nodes comprises:

[0043] S31: for any two connected multicast member nodes in the multicast tree, one of the multicast member nodes is used as a message sending node, and the other multicast member node is used as a message receiving node;

[0044] S32: The message sending node broadcasts the request message within its communication range, and receives a reply response to the request message, wherein the reply response records the propagation path of the request message and the location information of each node in the propagation path;

[0045] S33: the message sending node counts the reply responses within the timeout period set by it, and takes the propagation path of the reply response that includes the message receiving node as a candidate path set;

[0046] S34: Filter out the shortest routing path from the message sending node to the message receiving node from the candidate path set.

[0047] In order to better illustrate step S3 of the present invention, the present application provides the following embodiments:

[0048] Assume that in the space-ground integrated multicast network of the smart grid, a multicast tree has been constructed, and there are multiple multicast member nodes in the multicast tree, including source nodes and common member nodes. Now, two connected multicast member nodes A and B in the multicast tree are selected to explain the implementation process of step S3 in detail.

[0049] Case 1: Two nodes can communicate directly

[0050] If nodes A and B are within each other's communication range, and the signal strength and communication quality meet the requirements of direct communication, a routing link can be directly established between nodes A and B. For example, nodes A and B are adjacent ground substation communication nodes, the distance between them is short, and the communication frequency band and signal environment are good, so they can directly send and receive data. Then, a simple and direct routing link can be quickly established for multicast data transmission.

[0051] Case 2: Two nodes cannot communicate directly

[0052] If nodes A and B cannot communicate directly due to long distance, obstacles in between, or signal interference, follow these steps to build the shortest routing path:

[0053] Step S31: Node A is used as a message sending node, and node B is used as a message receiving node.

[0054] Step S32: Node A broadcasts a request message within its communication range. Assume that there are nodes C, D and E within the communication range of node A, and these three nodes receive the request message broadcast by node A.

[0055] Nodes C, D and E reply to the request message respectively. Taking node C as an example, it records the propagation path of the request message as A→C in the reply response, and records the location information of nodes A and C; node D records the propagation path as A→D, and records the location information of nodes A and D; the same is true for node E.

[0056] After receiving the request message, nodes C, D, and E will continue to broadcast the request message within their respective communication ranges. Assume that there are nodes F and G within the communication range of node C, node H within the communication range of node D, and node I within the communication range of node E. After receiving the message, these nodes will also reply and record the propagation path and location information.

[0057] Step S33: Node A sets a timeout period, such as 100 milliseconds, during which node A counts all received reply responses.

[0058] Node A screens the propagation paths of the reply response except those containing node B, and forms these paths into a candidate path set. Assume that after screening, paths A→C→F→B and A→D→H→B are obtained as candidate paths.

[0059] Step S34: Node A calculates the distance from node A to node B based on the node location information recorded in each path in the candidate path set. For example, for the path A→C→F→B, the total length of the path is calculated using the geographic distance formula based on the location information of each node; the same calculation is performed for the path A→D→H→B; the lengths of the paths are compared, and the shortest routing path is finally selected. Assuming that the calculation finds that the path A→C→F→B is shorter, then this path is used as the shortest routing path from node A to node B, and the corresponding routing link is constructed.

[0060] In this embodiment, the present invention can flexibly select the construction method of the routing link according to the actual communication situation between the multicast member nodes. For nodes that can communicate directly, the link is directly constructed, which reduces unnecessary intermediate links and improves communication efficiency; for nodes that cannot communicate directly, the shortest routing path is constructed through the relay node, which adapts to the complex network environment and ensures that the information can be accurately transmitted in various situations. By constructing the shortest routing path, the number of hops and distances in the data transmission process are reduced, and the network delay and energy consumption of data transmission are reduced. In the integrated network of the sky and the earth of the smart grid, this helps to improve the utilization of network resources and ensure the fast and accurate transmission of real-time data in the power system. By broadcasting request message packets and collecting reply responses, multiple possible routing paths can be found, and the shortest path is selected as the final routing link. This multi-path search and selection mechanism increases the reliability of communication. When a path fails or interferes, other paths can be reselected, which improves the stability of multicast routing.

[0061] Preferably, when a multicast member node exits the multicast tree, dynamic maintenance of the multicast tree exit is performed; the dynamic maintenance of the multicast tree exit includes:

[0062] When a multicast member node in a multicast tree exits the multicast tree, the multicast member node is regarded as a leaving node, and the smart grid central server deletes the leaving node and all edges connected to the leaving node from the multicast tree; when the number of edges connected to the leaving node is greater than or equal to 2, the multicast tree is divided into a source tree and one or more subtrees due to the departure of the multicast member, wherein the source tree is the multicast tree where the source node is located; for each subtree, the multicast member node connected to the leaving node is regarded as the head node of the subtree, and the following steps are performed to perform multicast tree maintenance: for the head node of each subtree, the search range of the head node is initialized and steps S23 to S26 are performed to search for the optimal candidate multicast member node of the head node, and the head node of each subtree is connected to its optimal candidate multicast member node to complete the dynamic maintenance of the exit of the multicast tree.

[0063] In this embodiment, it is assumed that a multicast tree has been constructed in the smart grid ground-to-ground integrated multicast network. The multicast tree includes a source node S, multicast member nodes A, B, C, D, E, F, etc., and their connection relationships are as follows: source node S connects A and B, A connects C and D, and B connects E and F. Now, it is assumed that multicast member node A wants to exit the multicast tree, and the following steps are performed to perform dynamic maintenance of multicast tree exit:

[0064] 1. Determine the leaving node and delete the related edges:

[0065] Multicast member node A is regarded as a leaving node, and the smart grid central server deletes node A and the edges connected to A from the multicast tree, namely, the connection edge between S and A, the connection edge between A and C, and the connection edge between A and D.

[0066] 2. Determine the changes in the multicast tree:

[0067] Since the number of edges connected to the leaving node A is 3, the multicast tree is divided into a source tree and two subtrees because of the leaving of node A. The source tree is the part of the multicast tree containing the source node S. At this time, S in the source tree is directly connected to B, and B is connected to E and F; one subtree contains node C, and one subtree contains node D, wherein nodes C and D connected to the leaving node A are respectively used as the head nodes of the corresponding subtrees; for the subtree with C as the head node; initialize the search range of C, for example, the area with C as the center and a radius of r0, and execute step S23: C searches for the remaining multicast member nodes within the search range. Assuming that D is searched within the range, execute step S24; Step S24: C determines whether the Euclidean distance between D and the source node S is less than the Euclidean distance between C and the source node. Assuming that the Euclidean distance between D and the source node S is smaller after calculation, D is added as a candidate multicast member node to the candidate multicast member node set. It is determined that the candidate multicast member node set is not empty, and step S25 is executed.

[0068] Step S25: Since there is only D in the candidate multicast node set, D is the candidate multicast member node with the smallest Euclidean distance to the source node, and C is connected to D. Assuming that C does not find a qualified node in the initial search range, execute step S26: expand the search range of C according to a preset ratio (such as 1.5 times) to an area with C as the center and a radius of 1.5r0, and then repeat steps S23-S26 in the new search range until a suitable connection node is found. Through the above steps, the dynamic maintenance of the multicast tree due to the exit of node A is completed.

[0069] In this embodiment, when a multicast member node exits, the node and related edges are deleted from the multicast tree in time, invalid connections and data transmission paths are avoided, and the clarity and effectiveness of the multicast tree structure are ensured. For the multicast tree that is split due to node exit, the multicast tree can continue to maintain a complete tree structure by reconnecting the subtrees, and the normal multicast communication is maintained. The split subtrees are maintained, and the optimal candidate multicast member nodes are searched and connected to ensure that each subtree can be reconnected to the multicast tree in a more reasonable way, avoiding the situation where some nodes cannot communicate due to node exit. This dynamic maintenance mechanism can adapt to the situation where nodes in the smart grid may change at any time, improve the reliability of multicast communication, and ensure the stability of data transmission in the power system. In the process of reconnecting the subtrees, the optimal candidate multicast member node is selected by calculating the Euclidean distance, which helps to optimize the topological structure of the multicast tree, make the data transmission path more reasonable, reduce transmission delay and energy consumption, and improve the overall performance of the multicast tree in the smart grid space-ground integrated network.

[0070] Preferably, when other non-multicast member nodes want to join the multicast tree, dynamic maintenance of joining the multicast tree is performed; the dynamic maintenance of joining the multicast tree includes:

[0071] When other non-multicast member nodes want to join the multicast tree, the node is used as the joining node, and the smart grid central server adds the joining node from the multicast tree and performs the following steps to maintain the multicast tree: for the joining node, initialize the search range of the joining node and execute steps S23 to S26 to search for the optimal candidate multicast member node of the joining node, and connect the joining node and its optimal candidate multicast member node to complete the dynamic maintenance of the joining of the multicast tree.

[0072] In this embodiment, it is assumed that a multicast tree has been constructed in the integrated multicast network of the smart grid. The multicast tree contains a source node S and multicast member nodes A, B, C, and D. The source node S is connected to nodes A and B, node A is connected to node C, and node B is connected to node D. Now there is a non-multicast member node E who wants to join this multicast tree, and the following steps are performed:

[0073] Determine the joining node: The smart grid central server identifies node E as a joining node and prepares to add it to the multicast tree.

[0074] Initialize the search range: For the added node E, initialize its search range. Assume that the initial search range is a circular area with node E as the center and radius r. '

[0075] Execute steps S23-S26:

[0076] Node E searches for other multicast member nodes within its initial search range. Assume that nodes A and C are found within the search range.

[0077] Node E determines whether the Euclidean distances between node A and node C and source node S are smaller than the Euclidean distance between node E and source node S. Assuming that the Euclidean distances between node A and node C and source node S are smaller than the Euclidean distance between node E and source node S, both node A and node C are added to the candidate multicast member node set as candidate multicast member nodes. Then, it is determined that the candidate multicast member node set is not empty, and step S25 is executed.

[0078] Step S25: Calculate the Euclidean distances between node A and node C and source node S. Assuming that the Euclidean distance between node A and source node S is smaller, node A is selected as the optimal candidate multicast member node. Then node E is connected to node A.

[0079] Assuming that node E does not find a candidate multicast member node that meets the conditions within the initial search range, the search range of node E is expanded according to a preset ratio (e.g., 1.5 times) to become a circular area with a radius of 1.5r and a center of node E. Then, steps S23-S26 are repeatedly performed within the new search range until a suitable optimal candidate multicast member node is found and the connection is completed.

[0080] In this scheme, non-multicast member nodes are allowed to join the multicast tree, so that the multicast network of the smart grid can be flexibly expanded according to actual needs. With the development and changes of the power system, new devices or nodes may need to join the multicast communication. This dynamic maintenance mechanism can easily accept new nodes to meet the growing communication needs. In the actual operation of the smart grid, the network topology may change frequently. The dynamic maintenance mechanism for joining the multicast tree can quickly respond to the joining request of new nodes, adjust the structure of the multicast tree in time, and ensure the stability and reliability of multicast communication. Even in a complex and changeable network environment, it can ensure that the newly joined nodes are smoothly integrated into the multicast network and achieve efficient data transmission. The smart grid central server uniformly manages the node joining process and completes the joining of new nodes through fixed steps (initializing the search range, searching for the best candidate node and connecting), making the process of node joining the multicast tree clear and simple, reducing the management complexity and operation and maintenance costs of the system.

[0081] In summary, the present invention can flexibly deal with such complex situations by finding relay nodes to build the shortest routing path, ensuring that effective communication links can be established between multicast members under various circumstances, greatly enhancing the adaptability and robustness of the solution in different scenarios. It can provide a stable and efficient transmission path for various multicast communication services of the smart grid in an integrated network environment between the sky and the earth. It ensures that key information such as real-time monitoring data and dispatching instructions of the power system are accurately and timely transmitted to multiple related nodes, thereby improving the reliability and efficiency of the entire smart grid communication system, and ultimately ensuring the safe and stable operation of the power system.

[0082] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the purpose and scope of the technical solution, which should be included in the scope of the claims of the present invention.

Claims

1. A space-ground integrated multicast routing method for smart grid, characterized in that: include: S1: The source node broadcasts a beacon message to wake up the selected multicast member nodes; S2: Build a multicast tree consisting of all multicast member nodes; S3: For any two connected multicast member nodes in the multicast tree, if the two connected multicast member nodes cannot communicate directly, the shortest routing path between the multicast member nodes is constructed according to the relay nodes between the multicast member nodes as the routing link between the two multicast members; if the two connected multicast member nodes can communicate directly, the routing link between the two multicast member nodes is directly constructed; multicast routing is performed through the routing link between the multicast members.

2. The method for integrating space and earth multicast routing for smart grid according to claim 1, characterized in that: The integrated space-ground network includes: m ground network nodes and n satellite network nodes, and all nodes are registered to the smart grid central server.

3. The method for integrating space and earth multicast routing for smart grid according to claim 2, characterized in that: The constructing of a multicast tree consisting of all multicast member nodes comprises: S21: connecting the satellite multicast member node to the terrestrial multicast member nodes within the coverage area; S22: Initialize the search range of each multicast member node, and calculate the Euclidean distance between each multicast member node and the source node; S23: for each multicast member node except the source node, searching for other multicast member nodes within the search range, if other multicast member nodes are found, executing step S24, otherwise executing step S26; S24: Determine whether the Euclidean distance between the remaining searched multicast member nodes and the source node is less than the Euclidean distance between the current multicast member node and the source node; if so, add the remaining multicast member nodes as candidate multicast member nodes to the candidate multicast member node set; then determine whether the candidate multicast member node set is empty, if so, execute step S26, otherwise execute step S25; S25: taking the candidate multicast member node with the smallest Euclidean distance to the source node in the candidate multicast node set as the optimal candidate multicast member node, and connecting the multicast member node to the optimal candidate multicast member node; S26: If the current multicast member node does not find a qualified candidate multicast member node within the search range, the search range of the current multicast member node is expanded according to a preset ratio, and steps S23 to S26 are repeatedly performed within the search range until a multicast tree consisting of all multicast member nodes is constructed.

4. The method for integrating space and earth multicast routing for smart grid according to claim 3, characterized in that: The constructing the shortest routing path between the multicast member nodes according to the relay nodes between the multicast member nodes comprises: S31: for any two connected multicast member nodes in the multicast tree, one of the multicast member nodes is used as a message sending node, and the other multicast member node is used as a message receiving node; S32: The message sending node broadcasts the request message within its communication range, and receives a reply response to the request message, wherein the reply response records the propagation path of the request message and the location information of each node in the propagation path; S33: the message sending node counts the reply responses within the timeout period set by it, and takes the propagation path of the reply response that includes the message receiving node as a candidate path set; S34: Filter out the shortest routing path from the message sending node to the message receiving node from the candidate path set.

5. The method for integrating space and earth multicast routing for smart grid according to claim 4, characterized in that: When a multicast member node exits the multicast tree, dynamic maintenance of the multicast tree exit is performed; The dynamic maintenance of multicast tree exit includes: When a multicast member node in a multicast tree exits the multicast tree, the multicast member node is regarded as a leaving node, and the smart grid central server deletes the leaving node and all edges connected to the leaving node from the multicast tree; when the number of edges connected to the leaving node is greater than or equal to 2, the multicast tree is divided into a source tree and one or more subtrees due to the departure of the multicast member, wherein the source tree is the multicast tree where the source node is located; for each subtree, the multicast member node connected to the leaving node is regarded as the head node of the subtree, and the following steps are performed to perform multicast tree maintenance: for the head node of each subtree, the search range of the head node is initialized and steps S23 to S26 are performed to search for the optimal candidate multicast member node of the head node, and the head node of each subtree is connected to its optimal candidate multicast member node to complete the dynamic maintenance of the exit of the multicast tree.

6. The method for integrating space and earth multicast routing for smart grid according to claim 5, characterized in that: When other non-multicast member nodes want to join the multicast tree, dynamic maintenance of multicast tree joining is performed; The dynamic maintenance of multicast tree joining includes: When other non-multicast member nodes want to join the multicast tree, the node is used as the joining node. The smart grid central server adds the joining node from the multicast tree and performs the following steps to maintain the multicast tree: For the joining node, the search range of the joining node is initialized and steps S23 to S26 are executed to search for the best candidate multicast member node of the joining node, and the joining node is connected to its best candidate multicast member node to complete the joining dynamic maintenance of the multicast tree.

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