Abstract: With the widespread application of Internet/Intranet technology, more and more application systems are developing towards Web-based directions, and the development of power plant management information systems also requires the public disclosure of various types of information. This paper introduces a Web-based power plant relay protection setting and information management system for power plant relay protection working groups, developed to meet this need. This system implements most of the functions required by the power plant relay protection group, including power plant relay protection configuration information, establishing graphical topology structures, protection setting, setting sheet processing, working group information management, network browsing, and query functions. The network module not only provides protection configuration information and corresponding setting status but also provides working group information management content. This content allows Internet users to access it through firewalls. The author believes that the setting work and information management of the working group should be integrated onto the network. The paper also introduces the overall structure and main functional modules of the system. Keywords: Relay protection; Setting calculation; Information management 1 Introduction The correctness and rationality of power plant protection settings are important guarantees for the safe and reliable operation of primary equipment. Although there are some stand-alone setting software programs available, their functions are limited to the setting process, and their information management capabilities for equipment are relatively weak. Furthermore, the systems are not flexible enough. With the widespread application of Internet/Intranet technology, more and more application systems are moving towards Web-based development. Therefore, it is entirely feasible to develop a Web-based setting software program for relay protection working groups that integrates information management. Currently, the "Guidelines for Relay Protection Setting Calculation of Large Generators and Transformers" has been officially released, and the conditions for developing system software with certain universality are mature. The network-based system software package introduced in this paper is for power plant relay protection working groups. It integrates power plant relay protection setting and information management, and its functions are relatively complete. 2 Overall Structure and Functional Modules The Web-based power plant relay protection setting and information management system is a relatively complete system for power plant relay protection working groups. The main tasks of the relay protection working group are: (1) Fault analysis and short-circuit current calculation. (2) Relay protection setting and maintenance of setting sheets. (3) Maintenance of equipment parameters and relay parameters. (4) Management of working group personnel and management of training materials. These functions are implemented on the server side, and the main structure of the server-side software is shown in Figure 1. The graphical modeling part is the foundation of the entire system; users can use its provided primitive object library to draw the power plant's equipment wiring diagrams. After the system wiring diagram is drawn, fault analysis and short-circuit current calculations can be performed directly through fault point settings. For the generator-transformer unit system, fault analysis provides the calculation curve method and the symmetrical component method, which can be selected by the user; for the plant auxiliary power system, fault analysis uses the symmetrical component method and can calculate the motor's self-starting condition. Protection setting is the core part of the system, with each module corresponding to a type of protection setting. The setting interface is designed to be simple and intelligent; for example, it can provide setting formulas, basic principles, and their sources to facilitate setting personnel in finding the theoretical basis. Currently, the setting principles for main equipment protection are based on the power industry standard DL/T 684-1999 "Guidelines for Setting and Calculating Relay Protection for Large Generators and Transformers" issued by the State Economic and Trade Commission of the People's Republic of China; while the plant auxiliary power system, due to its fewer protection types and simpler principles, selects commonly used typical protection principles. The system management is responsible for database maintenance. Its content includes equipment management, protection configuration information, setting and value sheets, system operator permission management, and protection group personnel information management. The network interface handles network client requests. Client requests include querying, browsing, and modifying some parameters. From the OSI (Open System Interconnection) network model perspective, client requests use the HTTP hypertext transfer protocol at the application layer, and data is transmitted through TCP packets and IP packets at the transport and network layers. These requests (packets) are captured, interpreted, and executed by ASP components on the server side, and the corresponding script programs are executed. The database interface is accessed through ADO (ActiveX Data Objects), and the corresponding data is returned, finally being sent back to the client in the form of packets. To handle server-side specific script commands, a scripting engine must be installed on the server side, such as IIS (Internet Information Server) running on NT or Win2000, or PWS (Personal Web Server) running on Win98. The entire system uses object-oriented programming methods, emphasizing visualization and modularity, expressing abstract structures or principles using vivid graphics and text. With the adoption of visual programming, the parameter reading and short-circuit current calculation of the equipment can be completed by simple click operation; during protection setting, the range of values ​​of each parameter can be prompted, and the correctness of the setting result can be judged, which is easy to implement. According to the function of the whole system, the system is divided into several functional modules, and each functional module is further divided until the smallest unit module, so as to ensure that the system has good expandability and versatility. According to the functional requirements of the system and the characteristics of software design, the whole system is divided into the following modules: (1) Graphic module The graphic module is the main tool module for establishing network topology diagrams. Users can draw the wiring diagram of the system through the graphic elements in the graphic element warehouse provided by the system and the connecting lines. Its network topology is automatically completed by the computer through the node connection status. Graphic modeling adopts visual programming, which is the basis for fault analysis calculation and protection setting calculation. The main functions implemented in the graphic modeling module are: 1) providing graphic element warehouse; 2) graphic editing; 3) graphic generation. Through graphic editing, the wiring diagrams of the plant power system and the generator-transformer group system can be generated, and each element on the graphic has its actual parameters, which can be used for fault analysis and short-circuit current calculation. (2) Fault Analysis Module The fault calculation module has the function of calculating short-circuit current when various types of faults occur at the lead-out terminals of the main equipment in the power plant. Specific functions include: 1) Fault points can be manually set, fault types can be set, and fault calculations can be performed. 2) For asymmetrical fault types, a sequence network diagram is automatically generated, namely positive sequence, negative sequence, and zero sequence diagrams. 3) Fault analysis result processing. The analysis results are output in tabular form, and specified data can be passed to the setting unit for setting calculation. (3) Protection Setting Module Protection setting is the core part of the software. There are not only many types of main equipment protection, but also differences in setting calculations for protections of the same principle produced by different manufacturers. Therefore, we first select from two types of protection setting tools: microcomputer protection and traditional protection, and then select according to multiple clues such as protection model (microcomputer protection), protection principle, manufacturer, and protected equipment. The main functions include: 1) Protection setting. Since there are many parameters involved, data that can be provided by the system, such as equipment parameters, can be automatically filled in by the program; for parameters determined by the user, a general range of values ​​is given for the user's reference; parameters that need to be obtained through fault calculation are provided by the fault analysis unit. 2) Setting reference. For each type of protection, the formula, principle, and source of reference materials for computer setting are provided for the user to search and analyze the setting process to ensure the correctness of the setting calculation. 3) Setting result processing. The setting result is first saved to the database, and a setting book is generated at the same time. The setting book includes the entire setting process. The setting sheet can be generated based on the data in the database. Both the setting sheet and the setting book can be printed in the form of a report. (4) Information management module The information management module includes setting system management, equipment information management and team information management. 1) Setting system management The setting sheet and setting book obtained from the setting process must also be managed and maintained. ① Maintenance of setting sheet attributes: The settings calculated by the protection setting module are trial settings that have not been approved for operation. In addition, there should be approved, currently operating, historical setting sheets or setting sheets that do not require setting calculation (such as non-electrical quantity protection); outdated setting sheets should be deleted, etc. Therefore, the attributes of the setting sheets must be properly maintained. ② Setting sheet query: Provides the function of querying specified setting sheets by protected equipment, protection principle, and setting sheet status. 2) Equipment information management includes the management of generators, transformers, and relay protection in power plants. It mainly provides functions such as adding and deleting equipment, inputting, modifying and deleting equipment parameters, managing equipment reports, and data backup. It can conveniently and flexibly log in, query, and statistically analyze the nameplate parameters, unit, and commissioning date of primary and secondary equipment in power plants. Equipment management provides parameters for all equipment in the power plant for short-circuit current calculation and protection setting services, and can also be viewed by users within the power plant's local area network. 3) Team Information Management: As a service system for protection work groups, this system provides daily team management, job training management, attendance management, rules and regulations management, and user permission management. Daily team management provides various work records, work plans and summaries, and the input, modification and query functions of the team leader's work log. Job training management provides interactive dialogue tools for job training, such as simulating the use of this system and using this system to find the principles and sources of protection settings. Attendance management provides daily attendance records, overtime registration, attendance statistics of team members and corresponding reports. Team rules and regulations are used for the maintenance and viewing of team rules and regulations. User permission management refers to the provision of corresponding functional modules according to the user's login level when the user uses this system. When the user accesses the system through the network, the operation functions that the user can have are also determined according to the login level. Users with high permissions can manage users with low permissions. (5) Network Interface Module: The network interface module is the main module for the system to implement network version functions. This system adopts the basic concept of Intranet, using the TCP/IP protocol within the local area network (LAN) and the Web model of the Internet as the standard platform. It also utilizes firewall technology to isolate the internal network from the Internet, allowing external networks to access some resources within the LAN. This module serves as the intermediary between network users and the system, primarily through network access to the database. As the main service system for the protection team, this system resides on the protection team's server within the power plant's LAN, providing network services to the entire power plant. Internet users can also access the system's webpage through a browser. The main functions provided by this module include: 1) Browsing power plant equipment wiring diagrams and protection configuration information. Users can directly click on the graphics of the main power plant equipment in the browser to display the protection configuration of that equipment. 2) Querying and browsing protection setting sheets and setting documents. Users can query setting sheets and setting documents by protection type, protected equipment, and setting sheet status. They can also query and analyze wiring diagrams and short-circuit point settings for corresponding faults. The graphically edited system wiring diagrams can be viewed by users on the network in MPEG format. 3) Query and browsing functions for team management information. Users can query various information related to team management via the network, including daily team management, job training management, attendance management, and rules and regulations management, etc. 3 Conclusion This paper focuses on the software structure of a networked power plant relay protection setting and information management system. In practical applications, this system avoids the shortcomings of stand-alone ordinary setting software in information management. It adopts a team-oriented design philosophy, providing more comprehensive and complete services to protection work groups. As part of the power plant management information system, it improves the overall information exchange and management level of the power plant. Through wide area network connectivity, it also enables remote querying, browsing, and message functions, facilitating experience exchange with other power plant colleagues. This system has achieved good application results in the Jiaxing Power Plant. Networking stand-alone software is an inevitable trend in software development. It can continuously absorb rapidly developing network technologies (such as wireless LAN technology) to better serve power plant users. The power plant relay protection setting and information management system for power plant work groups will continue to improve and mature with the development and application of information technology.