Multi-terminal relay protection system based on wireless local area network and operation method thereof

Abstract

The application discloses a kind of multi-terminal relay protection systems and its operating method based on wireless local area network, the system includes relay protection device, wireless communication module and at least one intelligent terminal.The application is realized based on Wi-Fi technology, and between relay protection device, wireless communication module and intelligent terminal, double authentication mode is set up, can more effectively prevent the invasion of illegal means such as eavesdropping, tampering, improve the security of power system, and will not cause the influence of original network of power plant.At the same time, the debugging and diagnosis operation of relay protection device of user through the system of the application is mainly realized through the application program of intelligent terminal, without relying on traditional key or notebook connection, especially suitable for offshore wind power, high-altitude installation and other space limited scenes, can reduce the work difficulty and intensity of engineer.The system and method of the application can significantly improve the work efficiency and work convenience of user, and is easy to implement, with good technical popularization value.

Description

Technical Field

[0001] This invention relates to the field of power system automation and human-machine interaction technology, specifically to a multi-terminal relay protection system based on a wireless local area network and its operation method. Background Technology

[0002] The existing human-machine interaction methods of relay protection devices mainly rely on local panel buttons or operation via a laptop connected to the network port. This has problems such as cumbersome operation, unfriendly interface, and inconvenient access. Especially in special scenarios such as offshore wind power and high-altitude installation, engineers need to work at heights or carry equipment to confined spaces, resulting in low debugging efficiency and safety hazards.

[0003] To improve the user experience, the industry has made a series of attempts. For example, the invention patent with publication number CN113488955A discloses a relay protection device and its adaptive human-computer interaction method and module. By setting the Bluetooth connection mode between the human-computer interaction module and the communication management module in the relay protection device, the human-computer interaction module can be set separately from the main unit and can be connected to other relay protection devices. The utility model patent with publication number CN212412746U discloses a multifunctional miniaturized relay protection device panel. In this design, the LCD panel is eliminated, and the dedicated equipment communicates directly with the device through the integrated wireless and wired modules.

[0004] First, the above methods share two common problems: First, security. The built-in wireless communication module is highly susceptible to providing intrusion channels for external connections. While CN113488955A incorporates BLE (Bluetooth Low Energy) key authentication for both the human-machine interface and communication modules, this authentication has numerous vulnerabilities, some of which are publicly known, making communication data vulnerable to hijacking and tampering. Second, cost. These methods require new device panels, rendering existing relay protection devices unusable via wireless connection, significantly increasing user learning and usage costs. Second, CN212412746U claims that eliminating the easily damaged LCD screen reduces failure rates and improves reliability; however, if the remote communication module malfunctions, on-site personnel cannot effectively diagnose and repair it. Third, CN113488955A connects to the human-machine interface module via Bluetooth. As is well known, Bluetooth's transmission rate in BLE mode is generally only 125 kbps - 2 Mbps, which cannot meet the real-time data refresh requirements and smooth multi-terminal access of modern relay protection devices.

[0005] Therefore, it is not difficult to see that some existing wireless control relay protection devices still have shortcomings in terms of poor safety, high cost, low transmission rate or inconvenience of use, and need to be further improved. Summary of the Invention

[0006] The technical objective of this invention is to provide a convenient multi-terminal relay protection system based on a wireless local area network and its operation method, thereby improving the efficiency of relay protection device debugging and diagnostic work and enhancing system security.

[0007] To achieve the above-mentioned technical objectives, the technical solution provided by the present invention includes the following aspects: In a first aspect, the present invention provides a multi-terminal relay protection system based on a wireless local area network, characterized in that it includes a relay protection device, a wireless communication module, and at least one smart terminal, wherein: The wireless communication module connects to the network port of the relay protection device via a network cable and serves as a Wi-Fi access point, providing a Wi-Fi network for smart terminals to access. The smart terminal is a mobile terminal running an application, and the user inputs commands through the user interface of the application. The relay protection device establishes a connection with the wireless communication module, and the relay protection device (1) performs connection authorization identification for the wireless communication module (4); the wireless communication module establishes a connection with the smart terminal, and the wireless communication module (4) performs connection authorization identification for the smart terminal (5); After the relay protection device and the wireless communication module successfully establish a connection, the relay protection device sends a temporary key to the wireless communication module for encryption and decryption of data transmitted between the relay protection device and the smart terminal.

[0008] Based on the above solutions, further improved or better solutions include: As one feasible implementation scheme, the system of the present invention includes: The relay protection device is equipped with a TCP server; The wireless communication module includes a TCP client, a UDP server, and a protocol conversion stack. The smart terminal is equipped with a UDP client; The wireless communication module establishes a connection with the TCP server of the relay protection device through a TCP client, and establishes a connection with the UDP client of the smart terminal through a UDP server; the protocol conversion stack is used to support data format conversion between TCP and UDP.

[0009] As one feasible implementation scheme, the system of the present invention includes: The relay protection device stores an encrypted first authentication code, which is bound to the identity of the wireless communication module and used by the relay protection device to identify the identity of the wireless communication module. The wireless communication module stores a second authentication code with read-only access permission. The second authentication code is bound to the identity of the smart terminal or the user and is used by the wireless communication module to identify the identity of the smart terminal or the user.

[0010] Preferably, the wireless communication module is an ESP32 communication module.

[0011] Secondly, the present invention provides an operation method for a multi-terminal relay protection system based on a wireless local area network as described above, characterized in that it includes: Create a TCP server in the relay protection device and enable the TCP server to access the local internal database of the relay protection device and provide data read and write services; Create a TCP client and a UDP server in the wireless communication module, and configure a protocol conversion stack that supports data format conversion between TCP and UDP; Create a UDP client in a smart terminal; The wireless communication module establishes a connection with the TCP server of the relay protection device through the TCP client, and establishes a connection with the UDP client of the smart terminal through the UDP server.

[0012] Furthermore, in the method of the present invention, after the user inputs a data request command through the application of the current smart terminal, the data request process in the system includes: S1. The UDP client adds the authentication code of the current smart terminal to the data request command, completes the data packaging, obtains the first command data packet, and sends the first command data packet to the UDP server of the wireless communication module. S2. After receiving the first instruction data packet sent by the UDP client, the UDP server adds the device serial number of the smart terminal requesting the data to the first instruction data packet, repackages it, and obtains the second instruction data packet; then encrypts the second instruction data packet with the key. S3. The TCP client of the wireless communication module extracts the encrypted second instruction data packet and sends it to the TCP server of the relay protection device; S4. After receiving the encrypted second instruction data packet, the TCP server decrypts the encrypted second instruction data packet. If the decrypted data request instruction content is valid, then step S5 is executed. S5. The TCP server reads the data from the relay protection device according to the data request instruction, encrypts the data requested by the user, and returns it to the TCP client of the wireless communication module. S6. After receiving the encrypted data returned by the TCP server, the TCP client decrypts it, adds the sequence number of the smart terminal that requested the data to the decrypted data, and repackages it. S7. The UDP server of the wireless communication module extracts the data repackaged in step S6 and returns the data packet to the UDP client of the corresponding smart terminal according to the device sequence number; After receiving the data packet returned by the wireless communication module, the S8.UDP client displays it through the application's user interface.

[0013] The key used for encryption / decryption in the above process is the temporary key.

[0014] Furthermore, the method of the present invention also includes an authentication process for identity recognition, the authentication process comprising: 1) The TCP server process of the relay protection device is initialized first, including registering access permissions for the local database of the relay protection device and initializing the TCP server thread. Then it starts listening and waits for the TCP client of the wireless communication module to connect. 2) After the wireless communication module is powered on, it retrieves the pre-stored first authentication code from the flash memory and assigns it to the corresponding variable, and then initializes the TCP client thread; the first authentication code is bound to the identity of the wireless communication module; When the wireless communication module is connected to the relay protection device and the TCP handshake is successful, the TCP server sends an authentication request, and the TCP client returns the first authentication code to it. If the first authentication code is deemed valid, the TCP server records the parsed first authentication code information and the TCP client's access time in the maintenance log, and returns a temporary key for encrypting and decrypting data to the wireless communication module through the TCP client. At the same time, the wireless communication module starts initializing the UDP server thread to wait for the smart terminal's UDP client to access. If the first authentication code is determined to be invalid, the TCP server will record the first authentication code information and the TCP client's access time, marking it as an invalid access. 3) When the user opens the application on the smart terminal and connects to the Wi-Fi network provided by the wireless communication module, the smart terminal UDP client thread is initialized and begins scanning for UDP servers; after the UDP server is scanned, the UDP client sends a second authentication code to the UDP server, and the second authentication code is bound to the identity of the user or smart terminal; If the second authentication code sent by the UDP client matches the second authentication code recorded in the flash memory of the wireless communication module, the second authentication code is considered valid, authentication is successful, and the UDP server and UDP client successfully establish a connection. If they do not match, the second authentication code is deemed invalid, and the UDP client's connection request is rejected.

[0015] Furthermore, the mode in which the relay protection device establishes a connection with the smart terminal through the wireless communication module is defined as the wireless operation mode of the relay protection device. In the method of this invention: To enable the wireless operation mode, users must enter the administrator password through the human-machine interface (HMI) of the relay protection device, thereby further enhancing system security.

[0016] Based on this, after the relay protection device is set to activate the wireless operation mode, the human-machine interface (HMI) of the relay protection device can be configured to block key value signals except for the reset button. The reset button is used to close the listening port of the TCP server and exit the wireless operation mode of the relay protection device.

[0017] In special circumstances, if multiple smart terminals establish connections with the same relay protection device within the same time period, and multiple users have the task of writing to the data storage unit of the relay protection device, such as setting set values, then only the first smart terminal that successfully establishes a connection with the relay protection device within that time period is allowed to have write operation permissions, in order to avoid data chaos and facilitate traceability.

[0018] Beneficial effects

[0019] Compared with the prior art, the present invention has the following technical effects: The system and method of this invention adopt a dual authentication mode of terminal and communication module, and employ a temporary key mechanism, which can more effectively prevent intrusion by illegal means such as eavesdropping and tampering, reduce the possibility of data being brute-forced, improve the security of the power system, and will not affect the original network of the power plant. 2) The system and method of this invention operate on the request data of the relay protection device through an application installed on a smart terminal. Different debugging and diagnostic functions can be easily implemented through configuration files without the need for costly hardware customization and adaptation for different projects and different models of devices. The usage is more flexible, and the smart terminal can be implemented using portable mobile devices such as mobile phones. With the addition of a Wi-Fi wireless communication module, it can be implemented directly on the hardware of the existing relay protection device without the need for major modification or remanufacturing of its hardware structure. This ensures the universality of the technology and reduces the cost of implementation and modification while improving work efficiency. 3) This invention supports parallel access from multiple terminals, eliminating the need for traditional buttons or laptop connections. It is particularly suitable for space-constrained scenarios such as offshore wind power and high-altitude installations, improving the efficiency of on-site commissioning and diagnostic work in similar situations and reducing the workload and difficulty for engineers. 4) In practical use, to further enhance system security, the system and method of the present invention can be configured to require the user's administrator password to be entered when the wireless operation mode of the relay protection device is turned on, on the relay protection device side; on the smart terminal side, the authentication code can be selectively bound to either the user or the mobile terminal, thus ensuring convenience of use while maintaining security.

[0020] 5) In a further embodiment, the system of the present invention adopts a WiFi hotspot + UDP mode, which can better ensure the smoothness of data transmission when multiple terminals access the system, thereby further improving work efficiency.

[0021] 6) The system and method of the present invention are easy to implement and can be modified on existing platforms, and have good promotion and application value. Attached Figure Description

[0022] Figure 1 This is a hardware connection diagram of the system of the present invention; Figure 2 This is a program architecture diagram of the system of the present invention; Figure 3 This is a data packet structure diagram of the system of the present invention; Figure 4 This is a data request flowchart of the system of the present invention; Figure 5 This is a flowchart of the authentication process of the present invention system; The reference numerals in the figure are as follows: 1-Relay protection device, 2-Maintenance network port, 3-Category 5 network cable, 4-Wireless communication module, 5-Smart terminal. Detailed Implementation

[0023] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments: like Figure 1 As shown, the multi-terminal relay protection system based on a local area network of the present invention includes components such as a relay protection device 1, a wireless communication module 4, and a smart terminal 5.

[0024] The relay protection device 1 supports the front panel maintenance network port 2 and has a fixed IP address.

[0025] The wireless communication module 4 serves as an access point for the Wi-Fi network, i.e., a Wi-Fi hotspot, providing access to the Wi-Fi network for the smart terminal 5. In this embodiment, an ESP32 communication module is used, which can be connected to the relay protection device 1 via a 100Mbps Ethernet cable (Category 5 cable 3) or a faster Ethernet cable, and is equipped with a battery compartment for independent power supply. The ESP32 communication module can also be replaced by other non-communication modules with similar functions, such as Realtek's RTL8720DN communication module and MediaTek's MT7697 communication module.

[0026] The smart terminal 5 is a portable mobile device, such as a mobile phone or tablet, with an application installed. The application can be a local program installed independently on the mobile device, or a WeChat mini-program, etc. The user operates through the application, accesses the wireless communication module 4 via Wi-Fi network, and then establishes a communication connection with the relay protection device 1, enabling the user to obtain information and interact with data from the relay protection device 1.

[0027] Figure 2 The diagram shows the program architecture of the system of the present invention, including: 1. A TCP server is created in the relay protection device 1, which can access the internal database of the relay protection device 1 and provide data read and write services; 2. Create a TCP client, a UDP server, and a protocol conversion stack in the ESP32 communication module. The ESP32 communication module establishes a communication connection with the relay protection device 1 through the TCP protocol and a communication connection with the smart terminal 5 through the UDP protocol. The protocol conversion stack supports data format conversion between TCP and UDP and has data caching and retransmission mechanisms to ensure the stability of debugging data transmission. 3. Create a UDP client in the smart terminal 5. The smart terminal 5 starts the UDP client through the application and sends UDP data packets to the ESP32 communication module.

[0028] Figure 3 The data packet structure of the system of the present invention is shown, wherein: The data packet structure of the UDP server of the smart terminal 5 includes the terminal's authentication code, the type code of the requested data, and the instruction sequence number (if any). The data packet structure of the ESP32 communication module includes a key and the device serial number of the smart terminal; The data packet structure of the TCP server of the relay protection device 1 includes data type code and specific data.

[0029] Table 1 shows some examples of instruction and data packet formats in this embodiment.

[0030] Table 1

[0031] like Figure 4 The diagram shown is a data request flowchart of the system of the present invention, which includes the following steps: a1) When a user launches a UDP client through the application of the smart terminal 5 to send a data request command, the UDP client adds an authentication code to the request command to complete the data packaging and sends it to the UDP server of the ESP32 communication module. For example, when the smart terminal 5 with authentication code NARI_38794_003 sends the first telemetry value request, its UDP client will send an instruction data packet of NARI_38794_003+MENU_MEAUSRE_YC+0x01 (authentication code + data type code + instruction sequence number) to the UDP server.

[0032] a2) After receiving the instruction data packet, the UDP server stores it in the cache pool, adds the device serial number of the smart terminal requesting the data to the original instruction data packet, repackages it, and encrypts the data packet with the key. For example, if the device serial number of the smart terminal 5 requesting data is 0x00, then the serial number 0x00 is added to the original instruction data packet and the packet is repackaged. Then, the repackaged data is encrypted with the key.

[0033] a3) The TCP client retrieves the repackaged and encrypted instruction data packet from the buffer pool and sends it to the TCP server of relay protection device 1; a4) After receiving the instruction data packet, the TCP server decrypts the instruction data packet and determines whether the content is valid. If it is invalid, it returns an error message to the corresponding smart terminal 5 along the original path. If it is valid, it proceeds to step a5). a5) After the TCP server reads the data requested by the user according to the instruction, it encrypts the data and sends it to the TCP client of the ESP32 communication module; For example, when relay protection device 1 returns the first telemetry value to smart terminal 5, the data packet contains MENU_MEAUSRE_YC+UAB0.000V0.000° (data type code + data).

[0034] a6) After the TCP client receives the data packet returned by the relay protection device 1, it decrypts the data packet and stores it in the cache pool. It then adds the device serial number of the smart terminal 5 that requested the data, such as 0x00, to the data packet in the cache pool and repackages it. a7) The UDP server reads the decrypted data packet with the smart terminal device sequence number added from the cache pool, and returns the data packet to the corresponding smart terminal 5 according to the sequence number; a8) After the UDP client receives the data packet, it displays it in the user interface of the Smart Terminal 5 application.

[0035] In this invention system, the authentication process between components is as follows: Figure 5 As shown, the process includes the following: When relay protection device 1 is turned on in wireless mode, the TCP server process clnp (command-link network process) is initialized first, including registering local database access permissions and initializing the TCP server thread, and then starts listening to wait for the ESP32 communication module to connect. After the ESP32 communication module powers on, it retrieves the first authentication code bound to its identity from the flash memory and assigns it to the corresponding variable, then initializes the TCP client. When the ESP32 communication module successfully completes a TCP handshake with the relay protection device 1, clnp sends an authentication request. The ESP32 module returns the first authentication code. If the first authentication code is valid, clnp records the parsed authentication code information and access time in the maintenance log and returns a temporary key for encrypting / decrypting data to the ESP32 module. At the same time, the ESP32 communication module initializes a UDP server thread to wait for the UDP client to connect. If the first authentication code is invalid, clnp records the authentication code information and access time, marks it as an illegal access, and closes the TCP client.

[0036] When a user opens the application on the smart terminal 5 and connects to the Wi-Fi network provided by the ESP32 communication module, the UDP client thread is initialized to scan for UDP servers. After a UDP server is found, the UDP client sends a second authentication code bound to itself or the user's identity to the UDP server. If the second authentication code matches at least one of the second authentication codes recorded in the flash memory of the ESP32 communication module, the second authentication code of the smart terminal 5 is considered valid, authentication is successful, and the UDP server establishes a connection with the UDP client. If they do not match, the second authentication code of the smart terminal 5 is deemed invalid, the connection request of the UDP client is rejected, an illegal access is marked, and the UDP client is closed.

[0037] The identity authentication process described above: i) After relay protection device 1 enters wireless operation mode, the HMI calls the shell script to run clnp. After the clnp process initializes, it creates and maintains a TCP server on the same network segment as network port 3 and starts listening clients. At the same time, the HMI blocks key signals except for the reset button to prevent accidental activation. To exit wireless operation mode, simply press the reset button. The HMI will then call the shell script to kill the clnp process and close the open socket port (listening port).

[0038] ii) When the ESP32 communication module is connected to the relay protection device 1, the user uses a network cable to connect the ESP32 communication module to the maintenance network port of the relay protection device 1. After the ESP32 communication module is powered on, it first initializes the data packet buffer pool, and then completes the creation and connection of the TCP client based on the IP of the maintenance network port and the port of the TCP server. After that, it uses the Wi-Fi module of the ESP32 communication module to create a hotspot, and finally creates a UDP server in the hotspot service thread and registers the data packet buffer pool.

[0039] iii) The format of the authentication code can be designed as: Project Code - Contract Number - Debugging Personnel Allowed Value. The relay protection device 1 locally stores the first authentication code encrypted with SHA-256, while in the ESP32 communication module, the first authentication code bound to itself and the second authentication code bound to the user or wireless terminal identity are stored in the flash partition customized by its ESP chip, realizing read-only access to prevent tampering.

[0040] (iiiii) During data transmission, data packets are forwarded after being unpacked and repackaged by the ESP32 communication module. The data packet structures sent and received by the ESP32 communication module are different. The data packets sent by the smart terminal 5 consist of an authentication code and a command, while the data packets received only contain the data returned by the clnp process. After each component completes authentication, the application of the smart terminal 5 sends the data request command data packet to the ESP32 communication module via UDP. The ESP32 communication module decompresses and caches the UDP packet in the cache pool, encrypts and packages it with the key, and sends it to the TCP server by the TCP client. clnp decompresses the data packet with the key, verifies the authentication code in the data packet, and if it is valid, returns the requested data; otherwise, it does not respond.

[0041] To further enhance system security, the system of this invention can also be configured so that when a user activates the wireless operation mode of the relay protection device 1, they must find the corresponding menu page in the HMI (Human-Machine Interface) of the relay protection device 1 and enter the administrator password. The application should also have user login authentication functionality.

[0042] The application program can perform debugging operations such as setting reading, modification, pressure plate activation / deactivation, and reset through the user interface. After completing dual authentication of the CLNP process authentication and wireless communication module authentication, the application program of the smart terminal 5 connects to the UDP server of the ESP32 communication module. The application program first sends a device type request command, and the relay protection device 1 returns the corresponding device type and database configuration initialization file. The application program generates corresponding function menus based on these files, including functions such as viewing real-time values ​​of analog quantities, viewing and setting events, activating and deactivating pressure plates, device testing, software updates, and waveform export. The offset range of each value is provided by the database configuration file. When the application sends a data request, if it requests an analog quantity, it sends an instruction containing the analog quantity keyword plus the required offset format to the CLNP process. The CLNP then searches the database and returns the corresponding value. When setting values ​​or platen activation / deactivation operations are required, the application integrates an OCR function. The user scans the setting sheet using the OCR function to complete the setting value entry, and then sends a write instruction to the CLNP process to complete the setting operation. This operation is only authorized to the first connected smart terminal (this design is for two reasons: first, setting values ​​requires writing the values ​​to the protection device's memory space, and to prevent multiple processes from writing to the same memory space simultaneously, only one terminal is allowed to have setting permissions; second, the wireless communication module is strongly associated with its holder, and all write operations will leave the holder's identity information, so allowing only one device to have setting permissions is for easy traceability). When file transfer is required, the file is temporarily stored in the cache space of smart terminal 5, facilitating data sharing between on-site personnel and back-end technical support, thus improving diagnostic efficiency.

[0043] The implementation scheme described in this invention is applicable to the commissioning phase before power plant startup and the fault diagnosis phase during shutdown maintenance, and does not affect network security issues during power plant operation and maintenance.

[0044] The above description is merely an implementation example of the present invention. It should be noted that, based on the above embodiments, various modifications and improvements can be made by those skilled in the art. Such modifications and improvements, without departing from the principle of the present invention, should also be considered within the scope of protection of the present invention.

Claims

1. A multi-terminal relay protection system based on a wireless local area network, characterized in that, It includes a relay protection device (1), a wireless communication module (4), and at least one smart terminal (5), wherein: The wireless communication module (4) is connected to the network port of the relay protection device (1) via a network cable and serves as a Wi-Fi access point to provide a Wi-Fi network for the smart terminal (5) to access; The smart terminal (5) is a mobile terminal running an application, and the user inputs instructions through the user interface of the application. A connection is established between the relay protection device (1) and the wireless communication module (4), and the relay protection device (1) performs connection authorization identification for the wireless communication module (4); a connection is established between the wireless communication module (4) and the smart terminal (5), and the wireless communication module (4) performs connection authorization identification for the smart terminal (5); After the relay protection device (1) and the wireless communication module (4) successfully establish a connection, the relay protection device (1) sends a temporary key to the wireless communication module (4) for encryption and decryption of data transmitted between the relay protection device (1) and the smart terminal (5) by the wireless communication module (4).

2. The multi-terminal relay protection system based on a wireless local area network as described in claim 1, characterized in that: The relay protection device (1) is equipped with a TCP server; The wireless communication module (4) is equipped with a TCP client, a UDP server, and a protocol conversion stack; The smart terminal (5) is equipped with a UDP client; The wireless communication module (4) establishes a connection with the TCP server of the relay protection device (1) through the TCP client, and establishes a connection with the UDP client of the smart terminal (5) through the UDP server. The protocol conversion stack is used to support the data format conversion between TCP and UDP.

3. The multi-terminal relay protection system based on a wireless local area network as described in claim 1, characterized in that: The relay protection device (1) stores an encrypted first authentication code, which is bound to the identity of the wireless communication module (4) and used by the relay protection device (1) to identify the identity of the wireless communication module (4). The wireless communication module (4) stores a second authentication code with read-only access permission. The second authentication code is bound to the identity of the smart terminal (5) or the user and is used by the wireless communication module (4) to identify the identity of the smart terminal (5) or the user.

4. A multi-terminal relay protection system based on a wireless local area network as described in any one of claims 1-3, characterized in that: The wireless communication module (4) adopts the ESP32 communication module.

5. The operation method of a multi-terminal relay protection system based on a wireless local area network as described in claim 1, characterized in that, include: Create a TCP server in the relay protection device (1) and enable the TCP server to access the internal database of the relay protection device (1) and provide data read and write services; Create a TCP client and a UDP server in the wireless communication module (4), and configure a protocol conversion stack that supports data format conversion between TCP and UDP; Create a UDP client in the smart terminal (5); The wireless communication module (4) establishes a connection with the TCP server of the relay protection device (1) through the TCP client, and establishes a connection with the UDP client of the smart terminal (5) through the UDP server.

6. The operation method of a multi-terminal relay protection system based on a wireless local area network as described in claim 5, characterized in that, After the user inputs a data request command through the application on the current smart terminal (5), the data request process in the system includes: S1. The UDP client adds the authentication code of the current smart terminal (5) to the data request instruction, completes the data packaging, obtains the first instruction data packet, and sends the first instruction data packet to the UDP server of the wireless communication module (4); S2. After receiving the first instruction data packet sent by the UDP client, the UDP server adds the device serial number of the smart terminal (5) requesting the data to the first instruction data packet, and repackages it to obtain the second instruction data packet; and encrypts the second instruction data packet with the key. S3. The TCP client of the wireless communication module (4) extracts the encrypted second instruction data packet and sends it to the TCP server of the relay protection device (1); S4. After receiving the encrypted second instruction data packet, the TCP server decrypts the encrypted second instruction data packet. If the decrypted data request instruction content is valid, then step S5 is executed. S5. The TCP server reads the data from the relay protection device (1) according to the data request instruction, encrypts the data requested by the user, and returns it to the TCP client of the wireless communication module (4); S6. After receiving the encrypted data returned by the TCP server, the TCP client decrypts it and adds the sequence number of the smart terminal (5) that requested the data to the decrypted data, and then repackages it. S7. The UDP server of the wireless communication module (4) extracts the data repackaged in step S6 and returns the data packet to the UDP client of the corresponding smart terminal (5) according to the device sequence number; After the S8.UDP client receives the data packet returned by the wireless communication module (4), it displays it in the user interface of the application.

7. The operation method of a multi-terminal relay protection system based on a wireless local area network as described in claim 5, characterized in that, This includes an authentication process for identity verification, the authentication process comprising: The TCP server process of the relay protection device (1) is initialized first, including registering the access permissions of the local database of the relay protection device and initializing the TCP server thread. Then it starts listening and waits for the TCP client of the wireless communication module (4) to connect. After the wireless communication module (4) is powered on, it retrieves the pre-stored first authentication code from the flash and assigns it to the corresponding variable, and then initializes the TCP client thread; the first authentication code is bound to the identity of the wireless communication module (4); When the wireless communication module (4) is connected to the relay protection device (1) and the TCP handshake is successful, the TCP server sends an authentication request and the TCP client returns the first authentication code to it. If the first authentication code is deemed valid, the TCP server records the parsed first authentication code information and the TCP client's access time in the maintenance log, and returns a temporary key for encrypting and decrypting data to the wireless communication module (4) through the TCP client. At the same time, the wireless communication module (4) starts to initialize the UDP server thread to wait for the access of the smart terminal (5) UDP client. If the first authentication code is determined to be invalid, the TCP server will record the first authentication code information and the TCP client's access time, marking it as an invalid access. When a user opens an application on a smart terminal (5) and connects to the Wi-Fi network provided by the wireless communication module (4), the UDP client thread of the smart terminal (5) is initialized and begins scanning for UDP servers. After scanning a UDP server, the UDP client sends a second authentication code to the UDP server. The second authentication code is bound to the identity of the user or the smart terminal (5). If the second authentication code sent by the UDP client is consistent with the second authentication code recorded in the flash of the wireless communication module (4), the second authentication code is deemed valid and the UDP server and the UDP client successfully establish a connection. If they do not match, the second authentication code is deemed invalid, and the UDP client's connection request is rejected.

8. The operation method of a multi-terminal relay protection system based on a wireless local area network as described in claim 5, characterized in that: The mode in which the relay protection device (1) establishes a connection with the smart terminal (5) through the wireless communication module (4) is defined as the wireless operation mode of the relay protection device (1); To enable the wireless operation mode, the user must complete the input of the administrator password through the human-machine interface (HMI) of the relay protection device (1).

9. The operation method of a multi-terminal relay protection system based on a wireless local area network as described in claim 8, characterized in that: After the relay protection device (1) is set to start wireless operation mode, the human-machine interface (HMI) of the relay protection device (1) will block key value signals except for the reset key. The reset key is used to close the listening port of the TCP server and exit the wireless operation mode of the relay protection device (1).

10. The operation method of a multi-terminal relay protection system based on a wireless local area network as described in claim 5, characterized in that: If multiple smart terminals (5) establish a connection with the same relay protection device (1) in the same time period, and multiple users have the task of writing to the data storage unit of the relay protection device (1), then only the first smart terminal (5) that successfully establishes a connection with the relay protection device (1) in that time period is allowed to have the permission to write.

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