Digital twin image data transmission and security control method and system in power transformation project

Abstract

A digital twin image data transmission and security control method and system in a power transformation project, comprising the following steps: step 1, collecting equipment data and image data of the construction site by sensors and cameras at regular intervals and fixed points; step 2, processing the collected data based on the MQTT protocol network, compressing the image data volume, and encoding and transmitting to the MQTT server; step 3, receiving and decoding the data encoded for security, setting up an MQTT server based on ABAC and encrypted channels combined with digital twin scenarios and construction site data, using WSO2 application servers and WSO2 identity authentication servers for identity and authorization management, secure transmission and remote control data, and visualizing production and operation scenarios. Through the implementation of high compression ratio image data transmission based on the MQTT protocol, the arrangement requirement of the on-site sensor is reduced. The attribute-based access control authorization technology is adopted to enhance the security and prevent illegal client intrusion and data leakage.

Description

Technical Field

[0001] The present invention belongs to the field of Internet of Things communication technology, and more specifically, relates to a method and system for digital twin image data transmission and safety control in a substation project. Background Art

[0002] Digital twin technology has demonstrated tremendous potential in sectors such as industry, manufacturing, and energy. By creating digital replicas of physical systems, it virtualizes them and provides a crucial tool for real-time monitoring, simulation, and predictive optimization. However, despite significant advances in data acquisition, real-time analysis, and control, digital twin technology still faces challenges in processing large amounts of data, particularly multimedia data such as video, images, and audio. While current IoT communication protocols are suitable for inter-device communication in constrained environments, they offer limited support for multimedia data transmission requiring large amounts of data and high bandwidth. This limits the breadth and efficiency of digital twin technology applications involving large-scale image and video processing.

[0003] MQTT, a common IoT communication protocol, features a streamlined design, low maintenance costs, and adaptability to low-bandwidth, high-latency, and unstable network environments. It offers flexible settings for the type and format of transmitted data, making it suitable for communication between IoT smart devices in constrained environments. However, the MQTT protocol has significant limitations when transmitting large amounts of data, such as video, images, and audio.

[0004] In the field of digital twin technology for power engineering infrastructure, in addition to real-time data collection of physical targets such as on-site equipment and personnel in infrastructure projects, it is also necessary to collect, transmit, and process multimedia data such as video, images, and audio. However, the MQTT protocol does not support multimedia data transmission with large amounts of data.

[0005] Prior art document 1 (CN112887429A) discloses a method, device, electronic device, and storage medium for data transmission. The method is executed by a sender terminal device and includes: receiving a network message sent by an MQTT service backend, determining the current network status of the sender terminal device based on the network message; determining whether the size of the original data in the original data queue exceeds a preset data threshold, and if so, compressing the original data based on the current network status to obtain compressed data; sending the compressed data to the MQTT service backend, so that the MQTT service backend can determine the current network status of the sender terminal device based on the sending time and receiving time of the compressed data, and writing the current network status into a network message and sending it to the sender terminal device.

[0006] The shortcomings of the existing technical document 1 are that it does not clearly describe the compression method and compression algorithm; there is no systematic security control mechanism, including permission control, encryption channel and other solutions; it cannot be applied to the processing of image files and cannot compress and transmit continuous image files. Summary of the Invention

[0007] In order to solve the deficiencies in the prior art, the present invention provides a method and system for digital twin image data transmission and safety control in substation projects, which overcomes the defects in real-time and reliability of image information transmission in the prior art.

[0008] The present invention adopts the following technical solutions.

[0009] A first aspect of the present invention provides a method for transmitting and safely controlling digital twin image data in a power transformation project, comprising the following steps:

[0010] Step 1: Use sensors and cameras to collect equipment data and image data at construction sites at fixed times and locations;

[0011] Step 2: Process the collected data based on the MQTT protocol network, compress the image data volume, and encode and transmit it to the MQTT server;

[0012] Step 3: Receive and decode the securely encoded data, establish an MQTT server based on ABAC and encrypted channels to combine the digital twin scenario with the construction site data, use the WSO2 application server and WSO2 identity authentication server to perform identity and authorization management, securely transmit and remotely control data, and visualize the production operation and maintenance scenario.

[0013] Preferably, in step 1, the data is divided into two categories: sensor data and image data; the transmission mode used includes 4G, 5G, serial communication and WiFi; and it is used for virtual-real linkage of the digital twin platform;

[0014] The sensor data is directly transmitted to the intelligent hardware gateway, and then sent to the MQTTBroker after preliminary encoding processing;

[0015] Image data is collected regularly by fixed-point cameras and transmitted to the intelligent hardware gateway for processing, cleaning and handling.

[0016] Preferably, in step 2, the data processing includes image data processing and sensor data processing;

[0017] Image data processing specifically includes the following steps:

[0018] Perform image block processing on the collected complete image data to decompose the large image into small sub-image blocks;

[0019] Applying linear interpolation to each sub-image block to smoothly segment the image;

[0020] The image data after the above processing is encoded and decoded with BASE64 to convert the invisible characters into visible characters.

[0021] Preferably, the image block processing includes decomposing the complete image into sub-images of N rows and M columns, and the sub-images overlap or connect with each other.

[0022] Preferably, the linear interpolation block segmentation algorithm specifically includes the following steps:

[0023] Calculate the global threshold: Use the maximum inter-class variance method to calculate the global threshold of each sub-image block;

[0024] Interpolation: Linear interpolation is performed between adjacent sub-image blocks according to the optimal segmentation threshold to achieve smooth transition.

[0025] Preferably, the maximum inter-class variance method specifically includes the following steps:

[0026] Assume that the number of pixels with grayscale value i in the image is n, and the total number of pixels is as follows:

[0027]

[0028] Where:

[0029] L-1 represents the maximum gray level of the image;

[0030] The probability formula for each gray value is as follows:

[0031] and

[0032] Assume that the segmentation threshold is t, and the image is divided into two parts according to the grayscale, including the target part and the background part; the grayscale of the target part is A = {0, 1, ..., t}, and the grayscale of the background part is B = {t+1, t+2, ..., L-1}. The probability formulas of the two parts appearing are as follows:

[0033]

[0034] The grayscale mean formulas for parts A and B are as follows:

[0035]

[0036] The formula for the total grayscale mean of the image is as follows:

[0037] u=P A u A +P B u B

[0038] The inter-class variance formulas for parts A and B are as follows:

[0039] σ 2 =P A (u A -u) 2 +P B (u B -u) 2

[0040] Where:

[0041] (u A -u) 2 Indicates the degree of deviation between the grayscale mean of the target part and the grayscale mean of the entire image;

[0042] (u B -u) 2 Indicates the degree of dispersion of the background part relative to the grayscale mean of the entire image;

[0043] Traverse t from the minimum grayscale value to the maximum grayscale value. When t maximizes the inter-class variance formula of parts A and B, t is the optimal threshold for segmentation. The formula is as follows:

[0044] t=ArgMax 0≤t≤L-1 σ 2 (t)

[0045] σ 2 (t) = P A (t)(u A (t)-u) 2 +P B (t)(u B (t)-u) 2

[0046] Where:

[0047] t represents the segmentation threshold, which is used to divide the image grayscale into the target part and the background part;

[0048] ArgMax 0≤t≤L-1 It means to find the value of t in the range 0≤t≤L-1 so that σ 2 to the maximum value;

[0049] P A (t) represents the probability of the target part (grayscale range is 0, 1,…, t);

[0050] u A (t) represents the grayscale mean of the target part;

[0051] P B(t) represents the probability of the background part (grayscale range is t+1, t+2,…, L-1);

[0052] u B (t) represents the grayscale mean of the background part;

[0053] u represents the grayscale mean of the entire image.

[0054] Preferably, the interpolation includes threshold interpolation between each sub-image block by linear interpolation. Assuming that the thresholds of the four adjacent areas are T1, T2, T3, and T4, the directions of linear interpolation between adjacent thresholds are T1→T2, T1→T3, T2→T4, and T3→T4. After interpolation, the adjacent thresholds have a smooth transition.

[0055] Preferably, in step 3, access control is established on entity attributes rather than user identity based on ABAC. In the ABAC model, access rights are granted based on attributes provided by the subject, and both the subject and the object are identified by attributes related to features.

[0056] Preferably, in step 3, the MQTT server based on ABAC access control capability includes an MQTT client, a WSO2 application server, a WSO2 identity authentication server and an MQTT server;

[0057] The MQTT client establishes a data transmission channel with the MQTT server through topic subscription and publication. Before subscribing and publishing, it needs to establish a connection with the server. After applying for CONNECT and obtaining confirmation from the server, the client starts to subscribe to and publish topics.

[0058] The WSO2 application server is used to intercept the connection request sent by the client in the MQTT communication and check the client's specific authorization;

[0059] The WSO2 Identity Server is an identity and authorization management server that supports OpenID and XACML. The Policy Decision Point (PDP) is used to store attribute-based policies and check authorization for requests to access specific applications. Through the policy check mechanism, it obtains the authorization status of the client requesting connection and sends it to the MQTT server.

[0060] The MQTT server's MQTT-based communication uses a broker to publish and subscribe to topics for message forwarding and storage. The PEP in the application server captures the request sent by the MQTT user and forwards it to the policy decision point PDP of the identity server for policy matching to decide whether to authorize the MQTT client's request.

[0061] A second aspect of the present invention provides a digital twin image data transmission and safety control system in a substation project, comprising: a data acquisition module, a data processing and transmission module, and a data management and visualization module;

[0062] The data acquisition module is used to collect various data from the construction site through sensors and cameras, and transmits them to the intelligent hardware gateway after preliminary processing;

[0063] The data processing and transmission module is used to clean, compress and encode data in the intelligent hardware gateway and transmit it through the MQTT Broker;

[0064] The data management and visualization module is used to integrate and map field data on the digital twin platform, visualize and command construction progress, safety management and remote monitoring.

[0065] Compared with the prior art, the beneficial effects of the present invention include at least:

[0066] (1) High compression ratio transmission of image data based on MQTT protocol network is realized. A data transmission control solution is provided for the virtual-real synchronization of digital twin of substation infrastructure construction progress.

[0067] (2) The present invention can significantly reduce the number of sensors deployed at the construction site, especially in the process of construction progress management, where the dynamic physical entity cannot be synchronized with the digital twin by setting up fixed sensors. Through fixed-point and timed image acquisition and transmission, the back-end can achieve functions such as construction progress management and safety risk identification through image recognition technology, and realize virtual-real linkage.

[0068] (3) Through the small-scale attribute-based access control authorization technology, the traditional MQTT protocol compensates for the security risk of no authorization mechanism in the state of multi-client asynchronous communication. It prevents illegal clients from invading the IoT system and causing data leakage or management risks. BRIEF DESCRIPTION OF THE DRAWINGS

[0069] Figure 1 It is a flow chart of digital twin image data transmission and safety control in substation engineering provided by the present invention;

[0070] Figure 2 It is a digital twin data transmission control logic diagram provided by the present invention;

[0071] Figure 3 This is a diagram of the intelligent gateway architecture provided according to an embodiment of the present invention;

[0072] Figure 4 is a schematic diagram of the linear interpolation direction of adjacent thresholds provided in accordance with an embodiment of the present invention;

[0073] Figure 5 This is a diagram of the MQTT protocol model provided in accordance with an embodiment of the present invention;

[0074] Figure 6 This is a diagram of the MQTT protocol model based on ABAC access control capabilities provided in accordance with an embodiment of the present invention. DETAILED DESCRIPTION

[0075] To make the objectives, technical solutions, and advantages of the present invention more clear, the technical solutions of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. The embodiments described in this application are only part of the embodiments of the present invention, not all of them. Based on the spirit of the present invention, other embodiments obtained by ordinary technicians in this field without making creative efforts are all within the scope of protection of the present invention.

[0076] like Figure 1 As shown, embodiment 1 of the present invention provides a method for digital twin image data transmission and safety control in a substation project, comprising the following steps:

[0077] Step 1: Collect construction site equipment data and image data through sensors and cameras;

[0078] Preferably, in step 1, the data is divided into two categories: sensor data and image data; the transmission methods used include 4G and 5G, serial communication and WiFi; and are used for virtual-real linkage of the digital twin platform;

[0079] The sensor data is directly transmitted to the intelligent hardware gateway, and then sent to the MQTT Broker (MQTT message server) after preliminary encoding processing;

[0080] Image data is collected regularly by fixed-point cameras and transmitted to the intelligent hardware gateway for processing, cleaning and processing. The image data needs to be processed, cleaned and processed before being sent to the MQTT Broker (MQTT message server).

[0081] Step 2: Process the collected data, compress the image data, and encode and transmit it to the MQTT (Message Queuing Telemetry Transport) server;

[0082] Preferably, in step 2, the image acquisition method for the infrastructure construction site is to use a fixed-point high-definition camera to take photos and collect them at fixed times, which is used for the virtual-real linkage of the digital twin platform, thereby realizing functions such as on-site construction progress, safe construction management, and construction operation. Since the amount of data collected by a single image is large, but the difference between the two images is small, the present invention adopts an image segmentation algorithm based on linear interpolation to perform differential image transmission. This method greatly compresses the amount of data transmitted by the image while ensuring that the image clarity is not distorted and data is not lost.

[0083] The significant difference between the present invention and the prior art lies in the different triggering mechanism for compressed data. The prior art determines whether the size of the original data in the original data queue exceeds a preset data threshold. If so, the original data is compressed according to the current network status to obtain compressed data; while the present invention compares two static images obtained continuously before and after, continuously compresses the image data, has no threshold concept, and has a very high compression ratio.

[0084] The data processing includes image data processing and sensor data processing;

[0085] Image data processing specifically includes the following steps:

[0086] The collected complete image data is processed in blocks, and the large image is decomposed into small sub-image blocks;

[0087] Applying linear interpolation to each sub-image block to smoothly segment the image;

[0088] The image data after the above processing is encoded and decoded with BASE64 to convert the invisible characters into visible characters.

[0089] Preferably, the image segmentation process includes decomposing the complete image into N rows and M columns of sub-images, with the sub-images overlapping or connected to each other. By dividing the complete image into smaller sub-images and segmenting them separately, the effects of shadows, lighting, and complex background on image segmentation are significantly reduced.

[0090] Preferably, the linear interpolation block segmentation algorithm specifically includes the following steps:

[0091] Calculate the global threshold: Use the maximum inter-class variance method to calculate the global threshold of each sub-image block;

[0092] Interpolation: Linear interpolation is performed between adjacent sub-image blocks according to the optimal segmentation threshold to achieve smooth transition.

[0093] Preferably, the maximum inter-class variance method specifically includes the following steps:

[0094] Assume that the number of pixels with grayscale value i in the image is n, and the total number of pixels is as follows:

[0095]

[0096] Where:

[0097] L-1 represents the maximum gray level of the image;

[0098] The probability formula for each gray value is as follows:

[0099] and

[0100] Assume that the segmentation threshold is t, and the image is divided into two parts according to the grayscale, including the target part and the background part; the grayscale of the target part is A = {0, 1, ..., t}, and the grayscale of the background part is B = {t+1, t+2, ..., L-1}. The probability formulas of the two parts appearing are as follows:

[0101]

[0102] The grayscale mean formulas for parts A and B are as follows:

[0103]

[0104] The formula for the total grayscale mean of the image is as follows:

[0105] u=P A u A +P B u B

[0106] The inter-class variance formulas for parts A and B are as follows:

[0107] σ 2 =P A (u A -u) 2 +P B (u B -u) 2

[0108] Traverse t from the minimum grayscale value to the maximum grayscale value. When t maximizes the inter-class variance formula of parts A and B, t is the optimal threshold for segmentation. The formula is as follows:

[0109] t=ArgMax 0≤t≤L-1 σ 2 (t)

[0110] σ 2 (t) = P A (t)(u A (t)-u)2 +P B (t)(u B (t)-u) 2

[0111] Where:

[0112] t represents the segmentation threshold, which is used to divide the image grayscale into the target part and the background part;

[0113] ArgMax 0≤t≤L-1 It means to find the value of t in the range 0≤t≤L-1 so that σ 2 to the maximum value;

[0114] P A (t) represents the probability of the target part (grayscale range is 0, 1,…, t);

[0115] u A (t) represents the grayscale mean of the target part;

[0116] P B (t) represents the probability of the background part (grayscale range is t+1, t+2,…, L-1);

[0117] u B (t) represents the grayscale mean of the background part;

[0118] u represents the grayscale mean of the entire image.

[0119] Preferably, the interpolation includes performing threshold interpolation between each sub-image block by linear interpolation in order to make the transition between each sub-image smooth. Assuming that the thresholds of the four adjacent regions are T1, T2, T3, and T4 respectively, the directions of linear interpolation between adjacent thresholds are T1→T2, T1→T3, T2→T4, and T3→T4, as shown in FIG. Figure 4 As shown in Figure 3, after interpolation, there is a smooth transition between adjacent thresholds.

[0120] The significant difference between the present invention and the prior art is that the prior art mainly focuses on the processing of audio data, such as compression, transmission, and storage; while the present invention mainly focuses on the processing of continuous static images, such as compression, transmission, and storage.

[0121] The significant difference between the present invention and the prior art lies in the different compression method. The prior art does not clearly explain the compression method and compression algorithm; while the present invention elaborates on the compression transmission algorithm of continuous images: adopts an image block segmentation algorithm based on linear interpolation, extracts image feature values, and compares two consecutive images by segmenting them into small images. Only images of areas where the difference in regional pixel feature values ​​exceeds a threshold are transmitted, and the image segmentation method is described in detail.

[0122] The present invention offers significant advantages over existing technologies in terms of data compression ratio, transmission security control mechanisms, data file restoration, and feature extraction for continuous image transmission over MQTT protocols. Existing technologies are not applicable to image file processing and are unable to compress and transmit continuous image files.

[0123] Preferably, BASE64 encoding and decoding: BASE64 converts invisible characters into visible characters, reducing errors caused by communication transmission. The BASE64 algorithm is less complex and relatively efficient, but BASE64 encoding has low security. The image encoding reference code is as follows:

[0124] importbase64

[0125] defimgToBase64(url):#BASE64 encode the image file

[0126] image_base64=""

[0127] with open(url,'rb')as f:

[0128] image_base64=base64.b64encode(f.read())

[0129] return image_base64

[0130] defBase64ToImg(image_base64):#Convert BASE64 code into image file

[0131] data_Image=base64.b64decode(image_base64)

[0132] with open('rec.jpg','wb')as file:

[0133] file.write(data_Image)

[0134] It is understandable that the MQTT protocol is lightweight and efficient, has a high compression ratio and low latency. It performs many-to-many messaging through a publish / subscribe model, supports multiple quality levels (QoS), and provides persistent sessions, retained messages, and will messages. It also has a flexible topic structure and strong security, which can achieve high compression ratio transmission.

[0135] Step 3: Receive and decode the securely encoded data, establish an MQTT server based on ABAC (Attribute-Based Access Control), and effectively combine the digital twin-based scenario with the production data, equipment online monitoring data, and on-site construction progress image monitoring data collected at the infrastructure construction site, including construction operation, construction management, and safety and environmental protection information monitoring visualization, which can realize remote construction progress monitoring, safety management, command and dispatch, and realize the visualization of production and operation scenarios.

[0136] Traditional MQTT protocol data is preferably transmitted unencrypted, and subscriber identity verification is subscription-based, resulting in high granularity and inability to implement refined permission control. Unlike traditional approaches, ABAC bases access control on entity attributes rather than user identity. In the ABAC model, access rights are granted based on the attributes provided by the subject, and both the subject and the object are identified by attribute-related properties.

[0137] Preferably, if Figure 6 As shown, in step 3, the MQTT server based on ABAC access control capability includes an MQTT client, a WSO2 application server, a WSO2 identity authentication server and an MQTT server;

[0138] The MQTT client establishes a data transmission channel with the MQTT server through topic subscription and publication. Before subscribing and publishing, it needs to establish a connection with the server. After applying for CONNECT and obtaining confirmation from the server, the client starts to subscribe to and publish topics.

[0139] The WSO2 application server is used to intercept the connection request sent by the client in the MQTT communication.

[0140] Check client-specific authorization;

[0141] The WSO2 Identity Server is an identity and authorization management server that supports OpenID and XACML. The Policy Decision Point (PDP) is used to store attribute-based policies and check authorization for requests to access specific applications. Through the policy check mechanism, it obtains the authorization status of the client requesting connection and sends it to the MQTT server.

[0142] The MQTT server's MQTT-based communication uses a broker to publish and subscribe to topics for message forwarding and storage. The PEP in the application server captures the request sent by the MQTT user and forwards it to the policy decision point PDP of the identity server for policy matching to decide whether to authorize the MQTT client's request.

[0143] This invention significantly differs from existing technologies in its security control mechanism. Existing technologies lack a systematic security control mechanism, including solutions such as permission control and encrypted channels. This invention, based on an ABAC-based security control strategy, establishes access control based on entity attributes rather than a system-level security control mechanism based on user identity. This provides a higher level of security, more flexible permission control, and wider adaptability.

[0144] The beneficial effect achieved by the present invention over the prior art is that it surpasses the prior art in terms of security control based on MQTT networks. The ABAC access control solution based on the MQTT protocol proposed by the present invention designs an access control implementation mechanism on the MQTT protocol, without modifying the MQTT message broker or client, and can be smoothly integrated into any network deployment based on the MQTT protocol. The solution uses the ABAC access control model because of its excellent flexibility and the dynamic and context-aware characteristics of the supported policies. It is very adaptable to dynamic environmental characteristics and reduces system overhead.

[0145] Example 2 of the present invention provides a digital twin image data transmission and safety control system in a substation project, including: a data acquisition module, a data processing and transmission module, and a data management and visualization module;

[0146] The data acquisition module is used to collect various data from the construction site through sensors and cameras, and transmits them to the intelligent hardware gateway after preliminary processing;

[0147] The data processing and transmission module is used to clean, compress and encode data in the intelligent hardware gateway and transmit it through the MQTT Broker;

[0148] The data management and visualization module is used to integrate and map field data on the digital twin platform, visualize and command construction progress, safety management and remote monitoring.

[0149] like Figure 2 As shown, Example 3 of the present invention provides a digital twin data transmission control logic, demonstrating the data processing and transmission process from the physical entity scene to the digital twin: physical sensors and image acquisition devices collect data, perform preliminary processing through the intelligent edge computing gateway, and then transmit the data to the MQTT server (broker) using the MQTT protocol. The MQTT server receives and manages the data and ultimately transmits it to the digital twin platform for further processing and analysis, generating a digital twin that reflects the state of the physical world in real time.

[0150] like Figure 3As shown, embodiment 4 of the present invention provides an intelligent hardware gateway that mainly collects equipment data at the construction site and cleans, processes, and stores it. After passing through the data acquisition module, data processing module, and data communication module, the data is finally transmitted to the MQTT Broker;

[0151] The data acquisition module includes a perception interface layer and a protocol adaptation layer, which are used to acquire and convert data formats. The data processing module is divided into a non-image data processing layer and an image data processing layer, the latter of which is further subdivided into image data processing, encoding, and compression layers.

[0152] The data communication module includes the MQTT protocol encoding layer and the communication layer, ensuring efficient data transmission through the MQTT protocol; the entire architecture uses a layered design to ensure efficient processing and management of data from collection to transmission.

[0153] like Figure 5 As shown, embodiment 5 of the present invention provides a basic architecture of the MQTT communication protocol, in which the publisher sends a message to the MQTT Broker, and the MQTT Broker distributes the message to the subscribers (Subscriber 1, Subscriber 2, Subscriber 3), thereby realizing efficient transmission and distribution of data.

[0154] The beneficial effects of the present invention include at least:

[0155] (1) High compression ratio transmission of image data based on MQTT protocol network is realized. A data transmission control solution is provided for the virtual-real synchronization of digital twin of substation infrastructure construction progress.

[0156] (2) The present invention can significantly reduce the number of sensors deployed at the construction site, especially in the process of construction progress management, where the dynamic physical entity cannot be synchronized with the digital twin by setting up fixed sensors. Through fixed-point and timed image acquisition and transmission, the back-end can achieve functions such as construction progress management and safety risk identification through image recognition technology, and realize virtual-real linkage.

[0157] (3) Through the small-scale attribute-based access control authorization technology, the traditional MQTT protocol compensates for the security risk of no authorization mechanism in the state of multi-client asynchronous communication. It prevents illegal clients from invading the IoT system and causing data leakage or management risks.

[0158] The present invention may be a system, a method and / or a computer program product. The computer program product may include a computer-readable storage medium carrying computer-readable program instructions for causing a processor to implement various aspects of the present invention.

[0159] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, ordinary technicians in the field should understand that the specific implementation methods of the present invention can still be modified or replaced by equivalents. Any modification or equivalent replacement that does not depart from the spirit and scope of the present invention should be covered by the scope of protection of the claims of the present invention.

Claims

1. A digital twin image data transmission and safety control method in a power transformation project, characterized in that: The following steps are involved: Step 1: Use sensors and cameras to collect equipment data and image data at construction sites at fixed times and locations; Step 2: Process the collected data based on the MQTT protocol network, compress the image data volume, and encode and transmit it to the MQTT server; The data processing includes image data processing and sensor data processing; Image data processing specifically includes the following steps: Perform image block processing on the collected complete image data to decompose the large image into small sub-image blocks; Applying linear interpolation to each sub-image block to smoothly segment the image; The processed image data is subjected to BASE64 encoding and decoding to convert invisible characters into visible characters; Step 3: Receive and decode the securely encoded data, establish an MQTT server based on ABAC access control and encrypted channels, combine the digital twin scenario with construction site data, and use the WSO2 application server and WSO2 identity authentication server to perform identity and authorization management, secure data transmission and remote control, and visualize production and operation scenarios.

2. The method for digital twin image data transmission and safety control in a power transformation project according to claim 1 is characterized in that: In step 1, the data is divided into two categories: sensor data and image data; the transmission methods used include 4G, 5G, serial communication and WiFi; the data is used for virtual-reality linkage of the digital twin platform; The sensor data is directly transmitted to the intelligent hardware gateway, where it is initially encoded and sent to the MQTT server. Image data is collected regularly by fixed-point cameras and transmitted to the intelligent hardware gateway for processing, cleaning and handling.

3. The method for digital twin image data transmission and safety control in a power transformation project according to claim 2 is characterized in that: The image block processing includes decomposing a complete image into sub-images of N rows and M columns, where the sub-images overlap or connect with each other.

4. The method for digital twin image data transmission and safety control in a power transformation project according to claim 2 is characterized in that: The linear interpolation block segmentation algorithm specifically includes the following steps: Calculate the global threshold: Use the maximum inter-class variance method to calculate the global threshold of each sub-image block; Interpolation: Linear interpolation is performed between adjacent sub-image blocks according to the optimal segmentation threshold to achieve smooth transition.

5. The method for digital twin image data transmission and safety control in a power transformation project according to claim 4 is characterized in that: The maximum between-class variance method, specifically The following steps are involved: Assume that the number of pixels with grayscale value i in the image is n, and the total number of pixels is as follows: Where: L-1 represents the maximum gray level of the image; The probability formula for each gray value is as follows: and Assume that the segmentation threshold is t, and the image is divided into two parts according to the grayscale, including the target part and the background part; the grayscale of the target part is A = {0, 1, ..., t}, and the grayscale of the background part is B = {t+1, t+2, ..., L-1}. The probability formulas of the two parts appearing are as follows: The grayscale mean formulas for parts A and B are as follows: The formula for the total grayscale mean of the image is as follows: u=P A in A +P B in B The inter-class variance formula of parts A and B is as follows: σ 2 =P A (in A -in) 2 +P B (in B -in) 2 Where: (u A -u) 2 Indicates the degree of deviation between the grayscale mean of the target part and the grayscale mean of the entire image; (u B -u) 2 Indicates the degree of dispersion of the background part relative to the grayscale mean of the entire image; Traverse t from the minimum grayscale value to the maximum grayscale value. When t maximizes the inter-class variance formula of parts A and B, t is the optimal threshold for segmentation. The formula is as follows: t=ArgMax 0≤t≤L-1 σ 2 (t) σ 2 (t)=P A (t)(u A (t)-u) 2 +P B (t)(u B (t)-u) 2 Where: t represents the segmentation threshold, which is used to divide the image gray level into the target part and the background part; ArgMax 0≤t≤L-1 It means to find the value of t in the range 0≤t≤L-1 so that σ 2 to the maximum value; P A (t) represents the probability of the target part with grayscale range of 0, 1,…, t; u A (t) represents the grayscale mean of the target part; P B (t) represents the probability of the background part with grayscale range t+1, t+2,…, L-1; u B (t) represents the grayscale mean of the background part; u represents the grayscale mean of the entire image.

6. The method for digital twin image data transmission and safety control in a power transformation project according to claim 2 is characterized in that: The interpolation includes threshold interpolation between each sub-image block by linear interpolation. Assuming that the thresholds of the four adjacent areas are T1, T2, T3, and T4, the directions of linear interpolation between adjacent thresholds are T1→T2, T1→T3, T2→T4, and T3→T4. After interpolation, the adjacent thresholds have a smooth transition.

7. The method for digital twin image data transmission and safety control in a power transformation project according to claim 1 is characterized in that: In step 3, access control is established based on entity attributes rather than user identity based on ABAC. In the ABAC model, access rights are granted based on the attributes provided by the subject, and both the subject and the object are identified by attributes related to characteristics.

8. A digital twin image data transmission and safety control method in a power transformation project according to claim 1 or 7, characterized in that: In step 3, the MQTT server based on ABAC access control capability includes an MQTT client, a WSO2 application server, a WSO2 identity authentication server, and an MQTT server; The MQTT client establishes a data transmission channel with the MQTT server through topic subscription and publication; Before subscribing and publishing, you need to establish a connection with the server. After applying for CONNECT and getting confirmation from the server, the client starts subscribing to and publishing the topic. The WSO2 application server is used to intercept the connection request sent by the client in the MQTT communication and check the client's specific authorization; The WSO2 Identity Server is an identity and authorization management server that supports OpenID and XACML. The Policy Decision Point (PDP) is used to store attribute-based policies and check authorization for requests to access specific applications. Through the policy check mechanism, it obtains the authorization status of the client requesting connection and sends it to the MQTT server. The MQTT server's MQTT-based communication uses a broker to publish and subscribe to topics for message forwarding and storage. The PEP in the application server captures the request sent by the MQTT user and forwards it to the policy decision point PDP of the identity server for policy matching to decide whether to authorize the MQTT client's request.

9. A digital twin image data transmission and safety control system in a substation project, comprising: Data acquisition module, data processing and transmission module, and data management and visualization module; characterized by: The data acquisition module is used to collect various data from the construction site through sensors and cameras, and transmits them to the intelligent hardware gateway after preliminary processing; The data processing and transmission module is used to clean, compress and encode data in the intelligent hardware gateway and transmit it through the MQTT server; The data processing includes image data processing and sensor data processing; Image data processing specifically includes the following steps: Perform image block processing on the collected complete image data to decompose the large image into small sub-image blocks; Applying linear interpolation to each sub-image block to smoothly segment the image; The processed image data is subjected to BASE64 encoding and decoding to convert invisible characters into visible characters; The data management and visualization module is used to integrate and map field data on the digital twin platform, visualize and command construction progress, safety management and remote monitoring; receive and decode securely encoded data, establish an MQTT server based on ABAC access control and encrypted channels, combine digital twin scenarios with construction site data, and use the WSO2 application server and WSO2 identity authentication server to perform identity and authorization management, secure data transmission and remote control, and visualize production and operation scenarios.

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